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Author name code: gopalswamy
ADS astronomy entries on 2022-09-14
author:"Gopalswamy, Nat" 

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Title: Effect of the Heliospheric State on CME Evolution
Authors: Dagnew, Fithanegest Kassa; Gopalswamy, Nat; Tessema, Solomon
   Belay; Akiyama, Sachiko; Yashiro, Seiji
2022ApJ...936..122D    Altcode:
  The culmination of solar cycle 24 by the end of 2019 has created
  the opportunity to compare the differing properties of coronal mass
  ejections (CMEs) between two whole solar cycles: solar cycle 23 (SC 23)
  and solar cycle 24 (SC 24). We report on the width evolution of limb
  CMEs in SCs 23 and 24 in order to test the suggestion by Gopalswamy et
  al. that CME flux ropes attain pressure balance at larger heliocentric
  distances in SC 24. We measure CME width as a function of heliocentric
  distance for a significantly large number of limb CMEs (~1000) and
  determine the distances where the CMEs reach constant width in each
  cycle. We introduced a new parameter, the transition height (hc) of a
  CME, defined as the critical heliocentric distance beyond which the CME
  width stabilizes to a quasi-constant value. Cycle and phase-to-phase
  comparisons are based on this new parameter. We find that the average
  value of hc in SC 24 is 62% higher than that in SC 23. SC 24 CMEs
  attain their peak width at larger distances from the Sun than SC 23
  CMEs do. The enhanced transition height in SC 24 is new observational
  ratification of the anomalous expansion. The anomalous expansion of
  SC 24 CMEs, which is caused by the weak state of the heliosphere,
  accounts for the larger heliocentric distance where the pressure
  balance between CME flux rope and the ambient medium is attained.

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Title: What Is Unusual About the Third Largest Geomagnetic Storm of
    Solar Cycle 24?
Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Xie, H.; Mäkelä,
   P.; Fok, M. -C.; Ferradas, C. P.
2022JGRA..12730404G    Altcode: 2022arXiv220711630G
  We report on the solar and interplanetary (IP) causes of the
  third largest geomagnetic storm (26 August 2018) in solar cycle
  24. The underlying coronal mass ejection (CME) originating from
  a quiescent filament region becomes a 440 km/s magnetic cloud
  (MC) at 1 au after ∼5 days. The prolonged CME acceleration (for
  ∼24 hr) coincides with the time profiles of the post-eruption
  arcade intensity and reconnected flux. Chen et al. (2019, <A
  href="https://doi.org/10.3847/1538-4357/ab3f36">https://doi.org/10.3847/1538-4357/ab3f36</A>)
  obtain a lower speed since they assumed that the CME does not
  accelerate after ∼12 hr. The presence of multiple coronal holes near
  the filament channel and the high-speed wind from them seem to have
  the combined effect of producing complex rotation in the corona and
  IP medium resulting in a high-inclination MC. The Dst time profile
  in the main phase steepens significantly (rapid increase in storm
  intensity) coincident with the density increase (prominence material)
  in the second half of the MC. Simulations using the Comprehensive Inner
  Magnetosphere-Ionosphere model show that a higher ring current energy
  results from larger dynamic pressure (density) in MCs. Furthermore,
  the Dst index is highly correlated with the main-phase time integral
  of the ring current injection that includes density, consistent with
  the simulations. A complex temporal structure develops in the storm
  main phase if the underlying MC has a complex density structure during
  intervals of southward IP magnetic field. We conclude that the high
  intensity of the storm results from the prolonged CME acceleration,
  complex rotation of the CME flux rope, and the high density in the
  1-au MC.

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Title: Effect of the Heliospheric State on CME Evolution
Authors: Kassa Dagnew, Fithanegest; Gopalswamy, Nat; Belay Tessema,
   Solomon; Akiyama, Sachiko; Yashiro, Seiji
2022arXiv220803536K    Altcode:
  The culmination of solar cycle 24 by the end of 2019 has created
  the opportunity to compare the differing properties of coronal mass
  ejections (CMEs) between two whole solar cycles: Solar cycle 23 (SC 23)
  and Solar cycle 24 (SC 24). We report on the width evolution of limb
  CMEs in SC 23 and 24 in order to test the suggestion by Gopalswamy
  et al. (2015a) that CME flux ropes attain pressure balance at larger
  heliocentric distances in SC 24. We measure CME width as a function
  of heliocentric distance for a significantly large number of limb CMEs
  (~1000) and determine the distances where the CMEs reach constant width
  in each cycle. We introduced a new parameter: the transition height (hc)
  of a CME defined as the critical heliocentric distance beyond which the
  CME width stabilizes to a quasi-constant value. Cycle and phase-to-phase
  comparisons are based on this new parameter. We find that the average
  value of hc in SC 24 is 62% higher than in SC 23. SC 24 CMEs attain
  their peak width at larger distances from the Sun as compared to SC
  23 CMEs. The enhanced transition height in SC 24 is new observational
  ratification of the anomalous expansion. The anomalous expansion of SC
  24 CMEs which is caused by the weak state of the heliosphere, accounts
  for the larger heliocentric distance where the pressure balance between
  CME flux rope and the ambient medium is attained.

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Title: Capacity Building Workshop on Coronal and Interplanetary
    Shocks in Kodaikanal
Authors: D'Amicis, Raffaella; Kathiravan, C.; Chellasamy Edwin,
   Ebenezer; Gopalswamy, Nat
2022cosp...44.3079D    Altcode:
  Space-based white-light coronagraph observations, radio spectral
  and imaging observations from space and ground are powerful tools to
  study and characterize interplanetary shocks driven by coronal mass
  ejections (CMEs). To encourage the scientific use of a wealth of data
  accumulated at the CDAW Data Center at NASA Goddard Space Flight Center
  including space missions (SOHO, GOES, SDO, STEREO, ACE), images of
  type II radio bursts from the Gauribidanur Radioheliograph (GRAPH),
  ground based radio data from the e-CALLISTO network and the Radio
  Solar Telescope Network around the globe, a two-week COSPAR Capacity
  Building Workshop was held in Kodaikanal, India, in 2020. This workshop
  was intended for scientists and students in developing countries (with
  particular reference to people from India, Pakistan, Africa, Malaysia,
  Indonesia, and Sri Lanka) where the e-CALLISTO instruments are deployed
  to perform joint studies using their data in conjunction with space
  data to investigate geoeffective solar transient phenomena. The workshop
  consisted of a series of introductory lectures on the Sun, Solar Corona,
  Interplanetary medium, Solar Eruptions, Shocks, and Solar Radio Bursts
  and also on Python software for data analysis. Several projects were
  undertaken by teams consisting of lecturers and students. In this
  presentation, we report about this successful workshop.

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Title: Halo coronal mass ejections, solar energetic particles,
    and sustained gamma-ray emission
Authors: Gopalswamy, Nat; Xie, Hong; Makela, Pertti; Yashiro, Seiji;
   Akiyama, Sachiko
2022cosp...44.1167G    Altcode:
  Halo coronal mass ejections (CMEs) are fast and wide and hence are
  very energetic. CMEs that produce space weather events such as intense
  geomagnetic storms and large solar energetic particle (SEP) events
  have high proportion of halo CMEs. One CME population has 100 percent
  halos: the CMEs associated with sustained gamma-ray emission (SGRE)
  from the Sun that last for at least 3 hours. CMEs associated with
  SGRE are ultrafast (average speed ~2000 km/s), very similar to CMEs
  that produce ground level enhancement (GLE) events. The SGRE - halo CME
  connection supports the idea that high-energy protons accelerated at the
  CME shock precipitate back to the solar surface, interact with ambient
  protons, and produce pion decay continuum observed as SGRE. In order
  to further clarify the relationship, we start with all ultrafast halo
  CMEs (sky-plane speed at least 1800 km/s) observed in solar cycles
  24 that had simultaneous gamma-ray observations from the Sun. We
  identified 20 such CMEs that have an average sky-plane speed of ~2142
  km/s, fourteen of which were frontsided. The soft X-ray flare sizes
  ranged from M3.7 to X8.2. We determined the CME kinematics using the
  graduated cylindrical shell model applied to SOHO and STEREO coronagraph
  data. The three-dimensional speed from the graduated cylindrical shell
  (GCS) model peaks at ≥2000 km/s (average 2698 km/s). The initial
  acceleration of the CMEs is &gt;1 km s-2 (average 3.5 km s-2). These
  speeds and accelerations are typical of GLE events, indicating strong
  shocks close to the Sun accelerating highest energy particles. When
  we examined the Fermi Large Area Telescope (Fermi/LAT) &gt;100 MeV
  gamma-ray data, we found that all but one of the 14 frontsided halo
  CMEs are associated with an SGRE event. The lone halo without SGRE had
  a Fermi/LAT data gap, so we cannot rule out the possibility of SGRE
  association. Among the 6 backside halo CMEs, one was associated with
  an SGRE, which is the famous 2014 September 1 event originating about
  40 degrees behind the limb. Two events had backside location similar
  to that of the 2014 September 1 event, but the flux rope orientation
  is north-south indicating a smaller longitudinal extent of the source
  region, so no SGRE is observed on the frontside. The remaining three
  events were too far behind the limb. We present additional information
  on the properties of the SEP events and interplanetary type II radio
  bursts that further support the CME-SGRE connection.

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Title: Flux Rope from Eruption Data (FRED) method applied to
    Earth-directed CMEs from solar cycles 23 and 24
Authors: Gopalswamy, Nat; Xie, Hong; Makela, Pertti; Yashiro, Seiji;
   Akiyama, Sachiko
2022cosp...44.2427G    Altcode:
  Only a fraction of an active region magnetic flux participates in a
  typical eruption. The total reconnected flux within the eruption area
  underlying post eruption arcades (PEAs) represents this fraction. The
  "flux rope from eruption data" or FRED refers to a technique that
  defines a coronal mass ejection (CME) flux rope based on the total
  reconnected flux during the eruption and geometric modeling of the
  white-light CMEs. One of the key features of FRED is that we know
  the axial magnetic field strength of the flux rope in the corona. If
  the flux rope expands self similarly, one can obtain its magnetic
  field components at any location in the heliosphere. This technique
  was applied previously to Earth-arriving CMEs of solar cycle 23 with
  encouraging results. Now that solar cycle 24 is complete, we apply the
  FRED technique to cycle 24 events and compare the results with those
  obtained for cycle 23.

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Title: Modeling the East-West Asymmetry of Energetic Particle Fluence
    in Large Solar Energetic Particle Events Using the iPATH Model
Authors: Ding, Zheyi; Li, Gang; Ebert, Robert W.; Dayeh, Maher A.;
   Fe-Dueñas, Adolfo Santa; Desai, Mihir; Xie, Hong; Gopalswamy, N.;
   Bruno, A.
2022JGRA..12730343D    Altcode:
  It has been noted that in large solar energetic particle (SEP) events,
  the peak intensities show an East-West asymmetry with respect to the
  source flare locations. Using the 2D improved Particle Acceleration and
  Transport in the Heliosphere (iPATH) model, we investigate the origin
  of this longitudinal trend. We consider multiple cases with different
  solar wind speeds and eruption speeds of the coronal mass ejections
  (CMEs) and fit the longitudinal distributions of time-averaged fluence
  by symmetric/asymmetric Gaussian functions with three time intervals of
  8, 24 and 48 hr after the flare onset time respectively. The simulation
  results are compared with a statistical study of three-spacecraft
  events. We suggest that the East-West asymmetry of SEP fluence and
  peak intensity can be primarily caused the combined effect of an
  extended shock acceleration process and the evolution of magnetic
  field connection to the shock front. Our simulations show that the
  solar wind speed and the CME speed are important factors determining
  the East-West fluence asymmetry.

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Title: Interhemispheric Asymmetries in Ionospheric Electron Density
Responses During Geomagnetic Storms: A Study Using Space-Based and
    Ground-Based GNSS and AMPERE Observations
Authors: Swarnalingam, N.; Wu, D. L.; Gopalswamy, N.
2022JGRA..12730247S    Altcode:
  We utilize Total Electron Content (TEC) measurements and electron
  density (Ne) retrieval profiles from Global Navigation Satellite System
  (GNSS) receivers onboard multiple Low Earth Orbit (LEO) satellites
  to characterize large-scale ionosphere-thermosphere system responses
  during geomagnetic storms. We also analyze TEC measurements from GNSS
  receivers in a worldwide ground-based network. Measurements from four
  storms during June and July 2012 (boreal summer months), December 2015
  (austral summer month), and March 2015 (equinoctial month) are analyzed
  to study global ionospheric responses and the interhemispheric asymmetry
  of these responses. We find that the space-based and ground-based TECs
  and their responses are consistent in all four geomagnetic storms. The
  global 3D view from GNSS-Radio Occultation (RO) Ne observations captures
  enhancements and the uplifting of Ne structures at high latitudes
  during the initial and main phases. Subsequently, Ne depletion occurs
  at high latitudes and starts progressing into midlatitude and low
  latitude as the storm reaches its recovery phase. A clear time lag
  is evident in the storm-induced Ne perturbations at high latitudes
  between the summer and winter hemispheres. The interhemispheric
  asymmetry in TEC and Ne appears to be consistent with the magnitudes
  of the Active Magnetosphere and Planetary Electrodynamics Response
  Experiment (AMPERE) high latitude integrated field-aligned currents
  (FACs), which are 3-4 MA higher in the summer hemisphere than in the
  winter hemisphere during these storms. The ionospheric TEC and Ne
  responses combined with the AMPERE-observed FACs indicate that summer
  preconditioning in the ionosphere-thermosphere system plays a key role
  in the interhemispheric asymmetric storm responses.

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Title: The Relation between Type III Radio Storms and CIR Energetic
    Particles
Authors: Gopalswamy, Nat; Mäkelä, Pertti; Yashiro, Seiji; Akiyama,
   Sachiko; Xie, Hong
2022arXiv220515852G    Altcode:
  We report on a study that compares energetic particle fluxes in
  corotating interaction regions (CIRs) associated with type III radio
  storm with those in nonstorm CIRs. In a case study, we compare the
  CIR particle events on 2010October 21 and 2005 November 2. The two
  events have similar solar and solar wind circumstances, except that
  the former is associated with a type III radio storm and has a higher
  CIR particle flux and fluence. We also perform a statistical study,
  which shows that the proton and electron fluences are higher in the
  storm associated CIRs by factor of about 6 and 8, respectively than
  those in the storm-free CIRs.

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Title: Can Type III Radio Storms be a Source of Seed Particles to
    Shock Acceleration?
Authors: Gopalswamy, Nat; Akiyama, Sachiko; Mäkelä, Pertti; Yashiro,
   Seiji; Xie, Hong
2022arXiv220515233G    Altcode:
  An intense type III radio storm has been disrupted by a fast halo
  coronal mass ejection (CME) on 2000 April 4. The CME is also associated
  with a large solar energetic particle (SEP) event. The storm recovers
  after about10 hrs. We identified another CME that occurs on 2003
  November 11 with similar CME properties but there is no type III storm
  in progress. The 2003 November 11 CME is also not associated with an SEP
  event above the background (less than 2 pfu), whereas the one with type
  III storm has an intense SEP event (about 56 pfu). One of the factors
  affecting the intensity of SEP events is the presence of seed particles
  that are accelerated by CME-driven shocks. We suggest that the type
  III storm source, which accelerates electrons to produce the storm,
  also accelerates ions that serve as seed particles to the CME shock.

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Title: Study of the Mass-loss Rate from the Sun
Authors: Michalek, Grzegorz; Gopalswamy, Nat; Yashiro, Seiji
2022ApJ...930...74M    Altcode:
  We investigate the temporal evolution of the yearly total mass-loss
  rate (YTMLR) from the Sun through coronal mass ejections (CMEs) over
  solar cycles 23 and 24. The mass determination of CMEs can be subject
  to significant uncertainty. To minimize this problem, we have used
  extensive statistical analysis. For this purpose, we employed data
  included in the Coordinated Data Analysis Workshop (CDAW) catalog. We
  estimated the contributions to mass loss from the Sun from different
  subsamples of CMEs (selected on the basis of their masses, angular
  widths, and position angles). The temporal variations of the YTMLR
  were compared to those of the sunspot number (SSN), X-ray flare flux,
  and the Disturbance Storm Time (Dst) index. We show that the CME mass
  included in the CDAW catalog reflects with high accuracy the actual
  mass-loss rate from the Sun through CMEs. Additionally, it is shown
  that the CME mass distribution in the log-lin representation reflects
  the Gaussian distribution very well. This means that the CMEs included
  in the CDAW catalog form one coherent population of ejections that
  have been correctly identified. Unlike the CME occurrence rate, it
  turns out that the YTMLR is a very good indicator of solar activity
  (e.g., SSN) and space weather (e.g., Dst index) consequences. These
  results are very important, since the YTMLR, unlike the mass loss
  through solar wind, significantly depends on solar cycles.

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Title: Modern Faraday Rotation Studies to Probe the Solar Wind
Authors: Kooi, Jason E.; Wexler, David B.; Jensen, Elizabeth A.;
   Kenny, Megan N.; Nieves-Chinchilla, Teresa; Wilson, Lynn B., III; Wood,
   Brian E.; Jian, Lan K.; Fung, Shing F.; Pevtsov, Alexei; Gopalswamy,
   Nat; Manchester, Ward B.
2022FrASS...941866K    Altcode:
  For decades, observations of Faraday rotation have provided unique
  insights into the plasma density and magnetic field structure of
  the solar wind. Faraday rotation (FR) is the rotation of the plane
  of polarization when linearly polarized radiation propagates through
  a magnetized plasma, such as the solar corona, coronal mass ejection
  (CME), or stream interaction region. FR measurements are very versatile:
  they provide a deeper understanding of the large-scale coronal magnetic
  field over a range of heliocentric distances (especially ≈1.5 to
  20 R⊙) not typically accessible to in situ spacecraft observations;
  detection of small-timescale variations in FR can provide information
  on magnetic field fluctuations and magnetohydrodynamic wave activity;
  and measurement of differential FR can be used to detect electric
  currents. FR depends on the integrated product of the plasma
  density and the magnetic field component along the line of sight
  to the observer; historically, models have been used to distinguish
  between their contributions to FR. In the last two decades, though,
  new methods have been developed to complement FR observations with
  independent measurements of the plasma density based on the choice
  of background radio source: calculation of the dispersion measure
  (pulsars), measurement of Thomson scattering brightness (radio
  galaxies), and application of radio ranging and apparent-Doppler
  tracking (spacecraft). New methods and new technology now make it
  possible for FR observations of solar wind structures to return not
  only the magnitude of the magnetic field, but also the full vector
  orientation. In the case of a CME, discerning the internal magnetic
  flux rope structure is critical for space weather applications.

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Title: Periodic Oscillations in LASCO Coronal Mass Ejection Speeds:
    Space Seismology
Authors: Michalek, Grzegorz; Gopalswamy, Nat; Yashiro, Seiji
2022ApJ...927L..16M    Altcode:
  Coronal mass ejections (CMEs) are energetic eruptions of organized
  magnetic structures from the Sun. Therefore, the reconnection of the
  magnetic field during ejection can excite periodic speed oscillations
  of CMEs. A previous study showed that speed oscillations are frequently
  associated with CME propagation. The Solar and Heliospheric Observatory
  mission's white-light coronagraphs have observed about 30,000 CMEs from
  1996 January to the end of 2019 December. This period of time covers two
  solar cycles (23 and 24). In the present study, the basic attributes of
  speed oscillations during this period of time were analyzed. We showed
  that the oscillation parameters (period and amplitude) significantly
  depend not only on the phase of a given solar cycle but also on the
  intensity of individual cycles as well. This reveals that the basic
  attributes of speed oscillation are closely related to the physical
  conditions prevailing inside the CMEs as well as in the interplanetary
  medium in which they propagate. Using this approximation, we estimated
  that, on average, the CME internal magnetic field varies from 18 up
  to 25 mG between minimum and maximum solar activity. The obtained
  results show that a detailed analysis of speed oscillations can be a
  very efficient tool for studying not only the physical properties of
  the ejections themselves but also the condition of the interplanetary
  medium in which they expand. This creates completely new perspectives
  for studying the physical parameters of CMEs shortly after their
  eruption in the Sun's environment (space seismology).

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Title: Eruption of the EUV Hot Channel from the Solar Limb and
    Associated Moving Type IV Radio Burst
Authors: Vemareddy, P.; Démoulin, P.; Sasikumar Raja, K.; Zhang,
   J.; Gopalswamy, N.; Vasantharaju, N.
2022ApJ...927..108V    Altcode: 2022arXiv220106899V
  Using the observations from the Solar Dynamics Observatory, we study
  an eruption of a hot-channel flux rope (FR) near the solar limb on 2015
  February 9. The pre-eruptive structure is visible mainly in EUV 131 Å
  images, with two highly sheared loop structures. They undergo a slow
  rising motion and then reconnect to form an eruptive hot channel,
  as in the tether-cutting reconnection model. The J-shaped flare
  ribbons trace the footpoint of the FR that is identified as the hot
  channel. Initially, the hot channel is observed to rise slowly at 40
  km s<SUP>-1</SUP>, followed by an exponential rise from 22:55 UT at a
  coronal height of 87 ± 2 Mm. Following the onset of the eruption at
  23:00 UT, the flare reconnection then adds to the acceleration process
  of the coronal mass ejection (CME) within 3 R <SUB>⊙</SUB>. Later
  on, the CME continues to accelerate at 8 m s<SUP>-2</SUP> during its
  propagation period. Further, the eruption also launched type II radio
  bursts, which were followed by type III and type IVm radio bursts. The
  start and end times of the type IVm burst correspond to the CME's
  core height of 1.5 and 6.1 R <SUB>⊙</SUB>, respectively. Also, the
  spectral index is negative, suggesting that nonthermal electrons are
  trapped in the closed loop structure. Accompanied by this type IVm
  burst, this event is unique in the sense that the flare ribbons are
  very clearly observed together with the erupting hot channel, which
  strongly suggests that the hooked parts of the J-shaped flare ribbons
  outline the boundary of the erupting FR.

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Title: VizieR Online Data Catalog: Solar coronal mass ejections with
    SOHO/LASCO (Dagnew+, 2020)
Authors: Dagnew, F. K.; Gopalswamy, N.; Tessema, S. B.; Akiyama, S.;
   Yashiro, S.; Tesfu, T. Y.
2022yCat..19030118D    Altcode:
  We used data (Gopalswamy+, 2010SunGe...5....7G) from the catalog
  that compiles all halo coronal mass ejections (HCMEs) manually
  identified from the Solar and Heliospheric Observatory Large Angle
  and Spectrometric Coronagraph Experiment (SOHO/LASCO) images within
  the C2 and C3 field of view (FOV). <P />(1 data file).

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Title: Solar activity and space weather
Authors: Gopalswamy, Nat; Mäkelä, Pertti; Yashiro, Seiji; Akiyama,
   Sachiko; Xie, Hong
2022JPhCS2214a2021G    Altcode: 2022arXiv220102724G
  After providing an overview of solar activity as measured by the sunspot
  number (SSN) and space weather events during solar cycles (SCs) 21-24,
  we focus on the weak solar activity in SC 24. The weak solar activity
  reduces the number of energetic eruptions from the Sun and hence the
  number of space weather events. The speeds of coronal mass ejections
  (CMEs), interplanetary (IP) shocks, and the background solar wind
  all declined in SC 24. One of the main heliospheric consequences of
  weak solar activity is the reduced total (magnetic + gas) pressure,
  magnetic field strength, and Alfvén speed. There are three groups
  of phenomena that decline to different degrees in SC 24 relative to
  the corresponding ones in SC 23: (i) those that decline more than
  SSN does, (ii) those that decline like SSN, and (iii) those that
  decline less than SSN does. The decrease in the number of severe
  space weather events such as high-energy solar energetic particle
  (SEP) events and intense geomagnetic storms is deeper than the
  decline in SSN. The reduction in the number of severe space weather
  events can be explained by the backreaction of the weak heliosphere
  on CMEs. CMEs expand anomalously and hence their magnetic content is
  diluted resulting in weaker geomagnetic storms. The reduction in the
  number of intense geomagnetic storms caused by corotating interaction
  regions is also drastic. The diminished heliospheric magnetic field
  in SC 24 reduces the efficiency of particle acceleration, resulting in
  fewer high-energy SEP events. The numbers of IP type II radio bursts,
  IP socks, and high-intensity energetic storm particle events closely
  follow the number of fast and wide CMEs (and approximately SSN) because
  all these phenomena are closely related to CME-driven shocks. The number
  of halo CMEs in SC 24 declines less than SSN does, mainly due to the
  weak heliospheric state. Phenomena such as IP CMEs and magnetic clouds
  related to frontside halos also do not decline significantly. The mild
  space weather is likely to continue in SC 25, whose strength has been
  predicted to be not too different from that of SC 24.

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Title: Arrival Time Estimates of Earth-Directed CME-Driven Shocks
Authors: Suresh, K.; Gopalswamy, N.; Shanmugaraju, A.
2022SoPh..297....3S    Altcode:
  We report on the travel times of 19 interplanetary (IP) shocks driven by
  Earth-directed coronal mass ejections (CMEs) that occurred from 2010 to
  2017. We track the shocks ahead of CMEs using the graduated cylindrical
  shell (GCS) model constructed from multiple-view observations from
  the Solar TErrestrial RElations Observatory (STEREO) and Solar
  and Heliospheric Observatory (SOHO) coronagraphs. We calculate the
  Earthward speed of the shocks from the height-time data obtained from
  the GCS fit that we use as input to the Empirical Shock Arrival (ESA)
  model to predict the shock travel times to 1 AU. We find that the mean
  absolute deviation (MAD) of the predicted IP shock travel time from
  the observed travel time is about 6.1 hours. The prediction error
  ranges from −14.3 hours to +13.1 hours with a standard deviation
  of 7.5 hours. The MAD and RMS errors are significantly smaller than
  those in the previous report (Gopalswamy et al., Space Weather11, 661,
  2013), which used SOHO-STEREO quadrature observations to obtain the
  Earthward speed of halo CMEs. The χ<SUP>2</SUP>-test confirms the high
  consistency level between predicted and observed travel times. These
  results suggest that the three-dimensional speeds of shocks can be
  derived using the GCS model outside of quadrature intervals and can
  be used in the determination of shock travel times.

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Title: Hemisphere-Asymmetric Responses of the Ionosphere to
    Geomagnetic Storms as Observed by GNSS and AMPERE
Authors: Swarnalingam, Nimalan; Wu, Dong; Gopalswamy, Nat
2021AGUFMSA24B..05S    Altcode:
  To characterize global ionosphere-thermosphere (IT) system responses
  during geomagnetic storms, we use electron density (Ne) and Total
  Electron Content (TEC) observations from space and ground for multiple
  storms, occurring in the boreal and austral summer months, as well
  as equinoctial month. The storm-induced Ne response in the summer
  and winter hemispheres appears to be different and asymmetric. The
  summer hemisphere shows a stronger response compared to the winter
  hemisphere. On the other hand, the response during the equinoctial
  month storm is more symmetric. The global 3D view from GNSS Radio
  Occultation (RO) Ne observation captures enhancements and uplifting of
  Ne structures at high latitudes during the initial and main phases. A
  clear time lag is evident in the storm-induced perturbation at high
  latitudes between the summer and winter hemispheres. Subsequently,
  Ne depletions occur at high latitudes. Time lag between high and mid
  latitudes is also evident, as the storm reaches its recovery phase. The
  observed hemispheric asymmetry in the ionospheric response appears to
  be consistent with AMPERE Field-Aligned Current (FAC) measurements. The
  integrated FACs in the summer hemisphere is a 4 - 5 MA higher than
  the winter hemisphere during these storms.

---------------------------------------------------------
Title: The Structural Connection between CME Flux Ropes near the
    Sun and at 1 AU
Authors: Xie, Hong; Gopalswamy, Nat; Akiyama, Sachiko
2021AGUFMSH35B2058X    Altcode:
  We preformed the first comprehensive statistical analysis comparing flux
  rope structures of coronal mass ejections (CMEs) near the Sun and at 1
  AU, using SOHO and STEREO measurements for the two full solar cycles
  of 23 and 24. The study aims to investigate the physical connection
  of 102 magnetic flux ropes (FR) among solar source regions, CMEs in
  the extended corona, and magnetic clouds (MCs) near Earth. Our main
  results include: 1) We confirmed that the hemispheric helicity rule
  holds true for $\sim$ 87\% of our 102 events. For the thirteen events
  that do not follow this rule, the FR axis directions and helicity signs
  can be inferred from soft X-ray and EUV images and magnetogram data in
  the source regions (e.g., coronal arcade skews, sigmoids, and magnetic
  tongues). 2) Around 25\% of the 102 events have rotations $&gt;$
  40\dg between the MC and CME--FR axial orientations. 3) For $\sim$56\%
  of these rotational events, the flux rope rotations occurred within
  the COR2 FOV, which can be predicted from the CME tilts obtained from
  flux rope fitting models. In addition, we found that for 89\% of the
  nineteen stealth CMEs under study, we can use the CNL locations and
  tilts to predict the flux rope helicity and its axial direction in
  the MCs. The above results would help to improve the prediction of the
  flux rope structures in situ. We discuss their implications on space
  weather forecasts.

---------------------------------------------------------
Title: Novel Magnetic Field and Electron Density Measurements of
    CMEs (within AU) with the Proposed Multiview Observatory for Solar
    Terrestrial Science (MOST) Mission
Authors: Jensen, P. E., C. S. P., Elizabeth; Manchester, Ward; Fung,
   Shing; Gopalswamy, Nat; Jian, Lan; Kenny, Megan; Kooi, Jason; Lazio,
   Joseph; Li, Lihua; Nieves-Chinchilla, Teresa; Pevtsov, Alexei; Wexler,
   David; Wilson, Lynn; Wood, Brian; Bale, Stuart; Bastian, Tim
2021AGUFMSH33A..08J    Altcode:
  The Multiview Observatory for Solar Terrestrial Science (MOST) mission
  concept will be the most advanced solar observatory to date (Gopalswamy
  et al, SH0001, 2021). Comprising four spacecraft, two located in the L4
  and ahead of L4 position and two located in the L5 and behind of the L5
  position, the four lines-of-sight (LOSs) form the basis for the unique
  Faraday Effect Tracker of Coronal and Heliospheric Structures (FETCH)
  instrument (Wexler et al, SH0019, 2021). We report on our modeling
  into the expected Faraday rotation (FR) caused by an Earth-directed
  CME crossing the MOST/FETCH radio-sensing paths using a heliospheric
  3-D MHD model to obtain the necessary LOS data on electron density
  and magnetic field components (see example image). Specifically, we
  utilized simulation data of the 2005 May 13 CME (Manchester IV et al.,
  2014, Plasma Phys. Control. Fusion), which erupted from the north-south
  polarity inversion line of AR 10759 at 16:03 UT, reaching speeds around
  2000 km/s in the corona. The trajectory of the CME at an acute angle
  to the Earth-Sun line crosses each FETCH LOS at a different time. Two
  LOSs are at different viewing angles with little overlap between
  the CME sheath and magnetic flux rope core. A blind test fitting of
  the Faraday rotation functions (Figures 6 and 7 in Jensen et al.,
  2010, Sol. Phys.) to the simulated FETCH observations reproduced the
  orientation of the CME for its handedness as well as its associated
  complementary degenerate solution. In conclusion, one of the four
  LOSs will be more sensitive to observing CME flux rope structure of
  Earthward CMEs, depending on their trajectory. We find that two of the
  four LOSs enable analyzing CME evolution, whereas the other two LOSs
  enable analyzing the average magnetic field vector in the corresponding
  high density regions dominating the measurements at that time. For
  example, the average sheath magnetic field vector can be partially
  measured in the plane of the ecliptic due to the angular differences
  between 2 LOSs. We discuss future work as this effort develops.

---------------------------------------------------------
Title: A Study on the Near-Sun Speed and Acceleration of CMEs
    Associated with Sustained Gamma-Ray Emission Events Observed by
    FERMI-LAT
Authors: Makela, Pertti; Gopalswamy, Nat; Xie, Hong; Akiyama, Sachiko;
   Yashiro, Seiji
2021AGUFMSH35E2118M    Altcode:
  Sustained gamma-ray emission (SGRE) events, also called late-phase
  gamma-ray emission (LPGRE) events, are solar eruptive events that
  produce long-lasting &gt;100 MeV gamma-ray flux. Enhanced gamma-ray
  emission can extend several hours after the impulsive phase of
  the associated solar flare. SGRE events have been detected since
  1980s, but the highly sensitive Large Area Telescope (LAT) on the
  FERMI spacecraft has observed SGREs more frequently since 2010. The
  &gt;100 MeV gamma-ray emission is generated by &gt;300 MeV protons via
  neutral pion production and decay. Flare-related processes or shock
  waves driven by coronal mass ejections (CMEs) have been suggested as
  possible acceleration mechanisms of the &gt;300 MeV protons. Previous
  studies have shown that SGRE events are associated with fast and wide
  halo CMEs. We describe in detail the near-Sun speed and acceleration of
  SGRE-event-associated CMEs and compare them with other CME populations
  without SGRE events. Fast acceleration suggests early shock formation
  with high speeds that are typical of ground level enhancement events
  and SGRE events indicating acceleration of high-energy particles. The
  height-time profiles are obtained by fitting 3D flux rope and shock
  wave models to the EUV and white-light images of the CME.

---------------------------------------------------------
Title: FETCH Concept: Investigating Quiescent and Transient Magnetic
    Structures in the Inner Heliosphere using Faraday Rotation of
    Spacecraft Radio Signals
Authors: Wexler, David; Jensen, Elizabeth; Gopalswamy, Nat; Wilson,
   Lynn; Fung, Shing; Nieves-Chinchilla, Teresa; Jian, Lan; Bastian,
   Tim; Pevtsov, Alexei; Manchester, Ward; Kenny, Megan; Lazio, Joseph;
   Wood, Brian; Kooi, Jason
2021AGUFMSH31A..05W    Altcode:
  The Faraday Effect Tracker of Coronal and Heliospheric structures
  (FETCH) is a new instrument concept being developed to probe coronal
  and interplanetary magnetic field structures in the ambient solar wind,
  corotating interaction regions and coronal mass ejections (CMEs) as
  they evolve in the inner heliosphere. FETCH is one of the instruments
  that constitute the Multiview Observatory for Solar Terrestrial (MOST)
  science mission. FETCH will measure Faraday rotation (FR) of linearly
  polarized spacecraft radio signals transmitted along four lines of sight
  provided by the four MOST spacecraft: two large spacecraft deployed
  at Sun-Earth Lagrange points 4 and 5 and two smaller spacecraft, one
  ahead of L4 and the other behind L5. FETCH will transmit and receive at
  selected radio frequencies in the 1-100 MHz range for lines of sight
  with solar impact parameters &lt; 0.5 AU. FR yields the line-of-sight
  (LOS) integrated product of electron number density and LOS-projected
  magnetic field strengths. The FR measurements will be obtained from
  the Stokes polarization parameters while additional plasma parameters,
  such as electron column density, will be extracted from other signal
  diagnostics. The multifrequency FR data and four lines-of-sight
  will be used to constrain the magnetic field topology and dynamics of
  interplanetary plasma structures upstream from Earth. Unique to this FR
  experiment, the FETCH transmitter-receiver instrumentation is positioned
  such that the entire sensing path remains in interplanetary space, thus
  avoiding the complications of trans-ionospheric FR observations. The
  FETCH key science objectives include: (1) characterizing CME magnetic
  field structure and flux rope orientation, (2) tracking CME propagation
  and shock signatures, (3) understanding the magnetic field features
  of corotating interaction regions in the extended corona and inner
  heliosphere, and (4) determination of large-scale MHD wave organization
  in regions of developed ambient solar wind and its evolution during
  perturbed flows. The MOST mission will build upon the achievements of
  the Solar Heliospheric Observatory (SOHO) and the Solar Terrestrial
  Relations Observatory (STEREO) missions during the last couple of
  decades. FETCH will help fill the long-standing measurement gap of
  magnetic field data in the inner heliosphere.

---------------------------------------------------------
Title: The Multiview Observatory for Solar Terrestrial Science (MOST)
Authors: Gopalswamy, Nat; Kucera, Therese; Leake, James; MacDowall,
   Robert; Wilson, Lynn; Kanekal, Shrikanth; Shih, Albert; Christe,
   Steven; Gong, Qian; Viall, Nicholeen; Tadikonda, Sivakumar; Fung,
   Shing; Yashiro, Seiji; Makela, Pertti; Golub, Leon; DeLuca, Edward;
   Reeves, Katharine; Seaton, Daniel; Savage, Sabrina; Winebarger, Amy;
   DeForest, Craig; Desai, Mihir; Bastian, Tim; Lazio, Joseph; Jensen,
   P. E., C. S. P., Elizabeth; Manchester, Ward; Wood, Brian; Kooi,
   Jason; Wexler, David; Bale, Stuart; Krucker, Sam; Hurlburt, Neal;
   DeRosa, Marc; Pevtsov, Alexei; Tripathy, Sushanta; Jain, Kiran;
   Gosain, Sanjay; Petrie, Gordon; Kholikov, Shukirjon; Zhao, Junwei;
   Scherrer, Philip; Woods, Thomas; Chamberlin, Philip; Kenny, Megan
2021AGUFMSH12A..07G    Altcode:
  The Multiview Observatory for Solar Terrestrial Science (MOST) is a
  comprehensive mission concept targeting the magnetic coupling between
  the solar interior and the heliosphere. The wide-ranging imagery and
  time series data from MOST will help understand the solar drivers and
  the heliospheric responses as a system, discerning and tracking 3D
  magnetic field structures, both transient and quiescent in the inner
  heliosphere. MOST will have seven remote-sensing and three in-situ
  instruments: (1) Magnetic and Doppler Imager (MaDI) to investigate
  surface and subsurface magnetism by exploiting the combination of
  helioseismic and magnetic-field measurements in the photosphere; (2)
  Inner Coronal Imager in EUV (ICIE) to study large-scale structures
  such as active regions, coronal holes and eruptive structures by
  capturing the magnetic connection between the photosphere and the
  corona to about 3 solar radii; (3) Hard X-ray Imager (HXI) to image
  the non-thermal flare structure; (4) White-light Coronagraph (WCOR) to
  seamlessly study transient and quiescent large-scale coronal structures
  extending from the ICIE field of view (FOV); (5) Faraday Effect
  Tracker of Coronal and Heliospheric structures (FETCH), a novel radio
  package to determine the magnetic field structure and plasma column
  density, and their evolution within 0.5 au; (6) Heliospheric Imager
  with Polarization (HIP) to track solar features beyond the WCOR FOV,
  study their impact on Earth, and provide important context for FETCH;
  (7) Radio and Plasma Wave instrument (M/WAVES) to study electron beams
  and shocks propagating into the heliosphere via passive radio emission;
  (8) Solar High-energy Ion Velocity Analyzer (SHIVA) to determine spectra
  of electrons, and ions from H to Fe at multiple spatial locations
  and use energetic particles as tracers of magnetic connectivity; (9)
  Solar Wind Magnetometer (MAG) to characterize magnetic structures at
  1 au; (10) Solar Wind Plasma Instrument (SWPI) to characterize plasma
  structures at 1 au. MOST will have two large spacecraft with identical
  payloads deployed at L4 and L5 and two smaller spacecraft ahead of L4
  and behind L5 to carry additional FETCH elements. MOST will build upon
  SOHO and STEREO achievements to expand the multiview observational
  approach into the first half of the 21st Century.

---------------------------------------------------------
Title: Earth-affecting solar transients: a review of progresses in
    solar cycle 24
Authors: Zhang, Jie; Temmer, Manuela; Gopalswamy, Nat; Malandraki,
   Olga; Nitta, Nariaki V.; Patsourakos, Spiros; Shen, Fang; Vršnak,
   Bojan; Wang, Yuming; Webb, David; Desai, Mihir I.; Dissauer, Karin;
   Dresing, Nina; Dumbović, Mateja; Feng, Xueshang; Heinemann, Stephan
   G.; Laurenza, Monica; Lugaz, Noé; Zhuang, Bin
2021PEPS....8...56Z    Altcode: 2020arXiv201206116Z
  This review article summarizes the advancement in the studies of
  Earth-affecting solar transients in the last decade that encompasses
  most of solar cycle 24. It is a part of the effort of the International
  Study of Earth-affecting Solar Transients (ISEST) project, sponsored
  by the SCOSTEP/VarSITI program (2014-2018). The Sun-Earth is an
  integrated physical system in which the space environment of the
  Earth sustains continuous influence from mass, magnetic field, and
  radiation energy output of the Sun in varying timescales from minutes to
  millennium. This article addresses short timescale events, from minutes
  to days that directly cause transient disturbances in the Earth's
  space environment and generate intense adverse effects on advanced
  technological systems of human society. Such transient events largely
  fall into the following four types: (1) solar flares, (2) coronal mass
  ejections (CMEs) including their interplanetary counterparts ICMEs,
  (3) solar energetic particle (SEP) events, and (4) stream interaction
  regions (SIRs) including corotating interaction regions (CIRs). In
  the last decade, the unprecedented multi-viewpoint observations of
  the Sun from space, enabled by STEREO Ahead/Behind spacecraft in
  combination with a suite of observatories along the Sun-Earth lines,
  have provided much more accurate and global measurements of the size,
  speed, propagation direction, and morphology of CMEs in both 3D and over
  a large volume in the heliosphere. Many CMEs, fast ones, in particular,
  can be clearly characterized as a two-front (shock front plus ejecta
  front) and three-part (bright ejecta front, dark cavity, and bright
  core) structure. Drag-based kinematic models of CMEs are developed to
  interpret CME propagation in the heliosphere and are applied to predict
  their arrival times at 1 AU in an efficient manner. Several advanced
  MHD models have been developed to simulate realistic CME events from
  the initiation on the Sun until their arrival at 1 AU. Much progress
  has been made on detailed kinematic and dynamic behaviors of CMEs,
  including non-radial motion, rotation and deformation of CMEs, CME-CME
  interaction, and stealth CMEs and problematic ICMEs. The knowledge
  about SEPs has also been significantly improved. An outlook of how to
  address critical issues related to Earth-affecting solar transients
  concludes this article.

---------------------------------------------------------
Title: High latitude coronal mass ejections during the solar
    maximum 24
Authors: Yashiro, Seiji; Gopalswamy, Nat; Akiyama, Sachiko
2021AGUFMSH35B2052Y    Altcode:
  We examined high latitude CMEs using a catalog of prominence
  eruptions (PEs) detected automatically in the SDO/AIA 304 Å
  Images (https://cdaw.gsfc.nasa.gov/CME_list/autope/). The source
  locations are listed in the prominence catalog, so we could exclude
  the low-latitude CMEs but appeared in the high latitude due to the
  projection effects. There are 115 high latitude PEs (Latitude&gt;= 60
  degree), but we could identify 60 CMEs only. The CME association rate
  is similar to the that of prominence eruptions observed by microwave
  (Gopalswamy et al. 2003, ApJ, 586, 562). Yashiro et al. (2020, JASTP,
  205, 105324) reported that the high-latitude PE speed decreased with
  decreasing average polar magnetic field strength, but we could not find
  such a clear relationship in the CME speed. The speed of high latitude
  CMEs are typically 400 km/s, but the CME speeds were occasionally high
  (e.g., ~700 km/s) when the prominence became jet-like CMEs. Because of
  the difference of the CME widths, the CME speed is not enough parameter
  to describe the CME kinematics. On the other hand, we found that the
  kinetic energy of the high latitude CMEs decreased with decreasing
  average magnetic field strength. Weaker field strengths indicate
  smaller amount of energy available to power the eruptions.

---------------------------------------------------------
Title: Spotless days and geomagnetic index as the predictors of
    solar cycle 25
Authors: Burud, Dipali S.; Jain, Rajmal; Awasthi, Arun K.; Chaudhari,
   Sneha; Tripathy, Sushanta C.; Gopalswamy, Nat; Chamadia, Pramod;
   Kaushik, Subhash C.; Vhatkar, Rajiv
2021RAA....21..215B    Altcode: 2021arXiv210511448B
  We study the sunspot activity in relation to spotless days (SLDs)
  during the descending phase of solar cycles 11-24 to predict the
  amplitude of sunspot cycle 25. For this purpose, in addition to
  SLD, we also consider the geomagnetic activity (aa index) during the
  descending phase of a given cycle. A very strong correlation of the SLD
  (0.68) and aa index (0.86) during the descending phase of a given cycle
  with the maximum amplitude of next solar cycle has been estimated. The
  empirical relationship led us to deduce the amplitude of cycle 25 to be
  99.13± 14.97 and 104.23± 17.35 using SLD and aa index, respectively
  as predictors. Both the predictors provide comparable amplitude for
  solar cycle 25 and reveal that solar cycle 25 will be weaker than cycle
  24. Further, we predict that the maximum of cycle 25 is likely to occur
  between February and March 2024. While the aa index has been utilized
  extensively in the past, this work establishes SLDs as another potential
  candidate for predicting the characteristics of the next cycle.

---------------------------------------------------------
Title: The Structural Connection between Coronal Mass Ejection Flux
    Ropes near the Sun and at 1 au
Authors: Xie, H.; Gopalswamy, N.; Akiyama, S.
2021ApJ...922...64X    Altcode:
  We have performed the first comprehensive statistical analysis comparing
  flux rope (FR) structures of coronal mass ejections (CMEs) near the
  Sun and at 1 au, using Solar and Heliospheric Observatory and Solar
  Terrestrial Relations Observatory measurements for the two full solar
  cycles 23 and 24. This study aims to investigate the physical connection
  of 102 magnetic FRs among solar source regions, CMEs in the extended
  corona, and magnetic clouds (MCs) near Earth. Our main results are as
  follows: (1) We confirmed that the hemispheric-helicity rule holds true
  for ~87% of our 102 events. For the 13 events that do not follow this
  rule, the FR axis directions and helicity signs can be inferred from
  soft X-ray and extreme ultraviolet images and magnetogram data in the
  source regions (e.g., coronal arcade skews, Fe XII stalks, sigmoids,
  and magnetic tongues). (2) Around 25% of the 102 events have rotations
  &gt;40° between the MC and CME-FR axial orientations. (3) For ~56%
  of these rotational events, the FR rotations occurred within the COR2
  field of view, which can be predicted from the CME tilts obtained from
  FR fitting models. In addition, we found that for 89% of the 19 stealth
  CMEs under study, we were able to use coronal neutral line locations and
  tilts to predict the FR helicity and its axial direction in the MCs. The
  above results should help improve the prediction of FR structures in
  situ. We discuss their implications on space weather forecasts.

---------------------------------------------------------
Title: Total Solar Irradiance Variability on the Evolutionary
    Timescale and its Impact on the Earth's Mean Surface Temperature
Authors: Shukure, N. T.; Tessema, S. B.; Gopalswamy, N.
2021ApJ...917...86S    Altcode: 2021arXiv210603657S
  The Sun is the primary source of energy for the Earth. The small changes
  in total solar irradiance (TSI) can affect our climate on the longer
  timescale. In the evolutionary timescale, the TSI varies by a large
  amount and hence its influence on the Earth's mean surface temperature
  (T<SUB>s</SUB>) also increases significantly. We develop a mass loss
  dependent analytical model of TSI in the evolutionary timescale
  and evaluated its influence on the T<SUB>s</SUB>. We determined
  the numerical solution of TSI for the next 8.23 Gyr to be used as
  an input to evaluate the T<SUB>s</SUB> which formulated based on a
  zero-dimensional energy balance model. We used the present-day albedo
  and bulk atmospheric emissivity of the Earth and Mars as initial and
  final boundary conditions, respectively. We found that the TSI increases
  by 10% in 1.42 Gyr, by 40% in about 3.4 Gyr, and by 120% in about 5.229
  Gyr from now, while the T<SUB>s</SUB> shows an insignificant change in
  1.644 Gyr and increases to 298.86 K in about 3.4 Gyr. The T<SUB>s</SUB>
  attains the peak value of 2319.2 K as the Sun evolves to the red giant
  and emits the enormous TSI of 7.93 × 10<SUP>6</SUP> W m<SUP>-2</SUP>
  in 7.676 Gys. At this temperature Earth likely evolves to be a liquid
  planet. In our finding, the absorbed and emitted flux equally increases
  and approaches the surface flux in the main sequence, and they are
  nearly equal beyond the main sequence, while the flux absorbed by the
  cloud shows the opposite trend.

---------------------------------------------------------
Title: Particle Acceleration and Transport at the Sun Inferred from
    Fermi/LAT Observations of &gt;100 MeV Gamma-rays
Authors: Gopalswamy, Nat; Mäkelä, Pertti; Yashiro, Seiji
2021arXiv210811286G    Altcode:
  The sustained gamma-ray emission (SGRE) events from the Sun are
  associated with an ultrafast (2000 km/s or greater) halo coronal mass
  ejection (CME) and a type II radio burst in the decameter-hectometric
  (DH) wavelengths. The SGRE duration is linearly related to the type
  II burst duration indicating that &gt;300 MeV protons required for
  SGREs are accelerated by the same shock that accelerates tens of keV
  electrons that produce type II bursts. When magnetically well connected,
  the associated solar energetic particle (SEP) event has a hard spectrum,
  indicating copious acceleration of high-energy protons. In one of the
  SGRE events observed on 2014 January 7 by Fermi/LAT, the SEP event
  detected by GOES has a very soft spectrum with not many particles
  beyond 100 MeV. This contradicts the presence of the SGRE, implying the
  presence of significant number of &gt;300 MeV protons. Furthermore, the
  durations of the type II burst and the SGRE agree with the known linear
  relationship between them (Gopalswamy et al. 2018, ApJ 868, L19). We
  show that the soft spectrum is due to poor magnetic connectivity
  of the shock nose to an Earth observer. Even though the location of
  the eruption (S15W11) is close to the disk center, the CME propagated
  non-radially making the CME flank crossing the ecliptic rather than the
  nose. High-energy particles are accelerated near the nose, so they do
  not reach GOES but they do precipitate to the vicinity of the eruption
  region to produce SGRE. This study provides further evidence that SGRE
  is caused by protons accelerated in shocks and propagating sunward to
  interact with the atmospheric ions.

---------------------------------------------------------
Title: The Common Origin of High-energy Protons in Solar Energetic
    Particle Events and Sustained Gamma-Ray Emission from the Sun
Authors: Gopalswamy, N.; Yashiro, S.; Mäkelä, P.; Xie, H.;
   Akiyama, S.
2021ApJ...915...82G    Altcode: 2021arXiv210501206G
  We report that the number of &gt;500 MeV protons (N<SUB>g</SUB>)
  inferred from sustained gamma-ray emission (SGRE) from the Sun is
  significantly correlated with that of protons propagating into space
  (N<SUB>SEP</SUB>) as solar energetic particles (SEPs). Under the
  shock paradigm for SGRE, shocks driven by coronal mass ejections
  (CMEs) accelerate high-energy protons sending them toward the Sun to
  produce SGRE by interacting with the atmospheric particles. Particles
  also escape into the space away from the Sun to be detected as SEP
  events. Therefore, the significant N<SUB>SEP</SUB>-N<SUB>g</SUB>
  correlation (correlation coefficient 0.77) is consistent with the
  common shock origin for the two proton populations. Furthermore, the
  underlying CMEs have properties akin to those involved in ground level
  enhancement events indicating the presence of high-energy (up to ~GeV)
  particles required for SGRE. We show that the observed gamma-ray flux is
  an underestimate in limb events (central meridian distance &gt;60°)
  because SGRE sources are partially occulted when the emission is
  spatially extended. With the assumption that the SEP spectrum at the
  shock nose is hard and that the 100 MeV particles are accelerated
  throughout the shock surface (half width in the range 60°-120°)
  we find that the latitudinal widths of SEP distributions are energy
  dependent with the smallest width at the highest energies. Not using the
  energy-dependent width results in an underestimate of N<SUB>SEP</SUB>
  in SGRE events occurring at relatively higher latitudes. Taking
  these two effects into account removes the apparent lack of
  N<SUB>SEP</SUB>-N<SUB>g</SUB> correlation reported in previous studies.

---------------------------------------------------------
Title: The Common Origin of High-energy Protons in Solar Energetic
    Particle Events and Sustained Gamma-ray Emission from the Sun
Authors: Gopalswamy, N.; Yashiro, S.; Makela, P.; Xie, H.; Akiyama, S.
2021AAS...23832208G    Altcode:
  We report on the correlation between the number of &gt;500 MeV
  protons (N<SUB>g</SUB>) deduced from the Fermi/LAT &gt;100 MeV
  sustained gamma-ray emission (SGRE) and the number of protons at 1
  au (N<SUB>SEP</SUB>) estimated from PAMELA mission's solar energetic
  particle (SEP) measurements. The correlation is highly significant with
  a correlation coefficient of 0.77 and hence supports the shock origin
  of &gt;300 MeV protons that interact with the solar chromosphere and
  resulting in pion decay observed as SGRE. The lack of correlation
  previously reported has been shown to be due to (i) a systematic
  underestimate of N<SUB>g</SUB> in events originating close to the limb
  owing to the spatially-extended nature of SGRE, and (ii) a systematic
  underestimate of N<SUB>SEP</SUB> in events originating at higher
  latitudes as a consequence of poor latitudinal connectivity. Correcting
  for these to effects, we find that the regression line is close to
  the N<SUB>g </SUB>= N<SUB>SEP</SUB> line. The close correlation found
  between N<SUB>SEP</SUB> and N<SUB>g</SUB> indicating their common
  origin (the CME-driven shock) is consistent with other significant
  correlations: (i) between the SGRE duration and the duration of the
  associated interplanetary type II radio burst, and (ii) between the
  SGRE fluence and CME speed.

---------------------------------------------------------
Title: Diffuse Interplanetary Radio Emission from a Polar Coronal
    Mass Ejection
Authors: Gopalswamy, N.; Makela, P.; Yashiro, S.; Akiyama, S.
2021arXiv210501216G    Altcode:
  We report on the first detection of nonthermal radio emission associated
  with a polar coronal mass ejection. We call the radio emission as
  diffuse interplanetary radio emission (DIRE), which occurs in the
  decameter-hectometric wavelengths. The radio emission originates from
  the shock flanks that interact with nearby streamers.

---------------------------------------------------------
Title: A Weak Fermi Gamma-ray Event Associated with a Halo CME and
    a Type II Radio Burst
Authors: Gopalswamy, N.; Mäkelä, P.; Yashiro, S.
2021arXiv210501212G    Altcode:
  We report on the 2015 June 25 sustained gamma-ray emission (SGRE) event
  associated with a halo coronal mass ejection and a type II radio burst
  in the decameter-hectometric (DH) wavelengths. The duration and ending
  frequency of the type II burst are linearly related to the SGRE duration
  as found in previous works involving intense gamma-ray events. This
  study confirms that the SGRE event is due to protons accelerated in
  the shock that produced the DH type II burst.

---------------------------------------------------------
Title: Investigating width distribution of slow and fast CMEs in
    solar cycles 23 and 24
Authors: Pant, V.; Majumdar, S.; Patel, R.; Chauhan, A.; Banerjee,
   D.; Gopalswamy, N.
2021FrASS...8...73P    Altcode: 2021arXiv210412850P
  Coronal Mass Ejections (CMEs) are highly dynamic events originating in
  the solar atmosphere, that show a wide range of kinematic properties
  and are the major drivers of the space weather. The angular width of the
  CMEs is a crucial parameter in the study of their kinematics. The fact
  that whether slow and fast CMEs (as based on their relative speed to
  the average solar wind speed) are associated with different processes at
  the location of their ejection is still debatable. Thus, in this study,
  we investigate their angular width to understand the differences between
  the slow and fast CMEs. We study the width distribution of slow and fast
  CMEs and find that they follow different power law distributions, with
  a power law indices ($\alpha$) of -1.1 and -3.7 for fast and slow CMEs
  respectively. To reduce the projection effects, we further restrict
  our analysis to only limb events as derived from manual catalog and
  we find similar results. We then associate the slow and fast CMEs to
  their source regions, and classified the sources as Active Regions
  (ARs) and Prominence Eruptions (PEs). We find that slow and fast CMEs
  coming from ARs and PEs, also follow different power laws in their
  width distributions. This clearly hints towards a possibility that
  different mechanisms might be involved in the width expansion of slow
  and fast CMEs coming from different sources.These results are also
  crucial from the space weather perspective since the width of the CME
  is an important factor in that aspect.

---------------------------------------------------------
Title: Imaging and Spectral Observations of a Type-II Radio Burst
    Revealing the Section of the CME-Driven Shock That Accelerates
    Electrons
Authors: Majumdar, Satabdwa; Tadepalli, Srikar Paavan; Maity,
   Samriddhi Sankar; Deshpande, Ketaki; Kumari, Anshu; Patel, Ritesh;
   Gopalswamy, Nat
2021SoPh..296...62M    Altcode: 2021arXiv210309536M
  We report on a multi-wavelength analysis of the 26 January 2014 solar
  eruption involving a coronal mass ejection (CME) and a Type-II radio
  burst, performed by combining data from various space and ground-based
  instruments. An increasing standoff distance with height shows the
  presence of a strong shock, which further manifests itself in the
  continuation of the metric Type-II burst into the decameter-hectometric
  (DH) domain. A plot of speed versus position angle (PA) shows different
  points on the CME leading edge traveled with different speeds. From the
  starting frequency of the Type-II burst and white-light data, we find
  that the shock signature producing the Type-II burst might be coming
  from the flanks of the CME. Measuring the speeds of the CME flanks,
  we find the southern flank to be at a higher speed than the northern
  flank; further the radio contours from Type-II imaging data showed that
  the burst source was coming from the southern flank of the CME. From
  the standoff distance at the CME nose, we find that the local Alfvén
  speed is close to the white-light shock speed, thus causing the Mach
  number to be small there. Also, the presence of a streamer near the
  southern flank appears to have provided additional favorable conditions
  for the generation of shock-associated radio emission. These results
  provide conclusive evidence that the Type-II emission could originate
  from the flanks of the CME, which in our study is from the southern
  flank of the CME.

---------------------------------------------------------
Title: On the Connection between Solar Surface Magnetic Flux and
    the Total Solar Irradiance
Authors: Shukure, N. T.; Tessema, S. B.; Gopalswamy, N.
2021ApJ...907...39S    Altcode:
  Solar surface magnetic flux evolution plays a dominant role in the
  variability of total solar irradiance (TSI). Different proxies of
  magnetic activity have been introduced to correlate solar variability
  and TSI. We present the daily strong flux densities (SFDs) and
  weak flux densities (WFDs) defined with three magnetic thresholds
  calculated from the Solar Dynamic Observatory/Helioseismic Magnetic
  Imager. TSI measurements are from the radiometers of the Variability of
  Solar Irradiance and Gravity Oscillations experiment on the Solar and
  Heliosphere Observatory, and sunspot area (SSA) is from the National
  Oceanic and Atmospheric Administration. We characterize the influence
  of the magnetic flux density variation on the TSI using the Pearson,
  Spearman, and percentage bend correlations and wavelet analysis between
  the TSI and the flux density. The Pearson's correlation shows that the
  TSI is negatively and strongly correlated with SFD and moderately with
  SSA; Spearman and 20% bend correlation shows that the TSI is moderately
  correlated with SFD and weakly with SSA on solar maximum, but weakly
  correlated on solar minimum. However, the TSI is not correlated with
  WFD during solar maximum and minimum. The bootstrapping tests also
  confirm that the influence of SFD on TSI is more significant than that
  of SSA. Finally, a wavelet analysis supports the idea that the SFD and
  TSI have a causality linkage and that the SFD dominantly influences
  the TSI variability on the rotational timescale.

---------------------------------------------------------
Title: INterplanetary Flux ROpe Simulator (INFROS): Predicting the
    magnetic-field vectors of ICMEs
Authors: Srivastava, Nandita; Gopalswamy, Nat; Sarkar, Ranadeep
2021cosp...43E1029S    Altcode:
  We have developed an observationally constrained analytical model,
  the INterplanetary Flux ROpe Simulator (INFROS), for predicting
  the magnetic-field vectors of interplanetary coronal mass ejections
  (ICMEs). The main architecture of INFROS uses the near-Sun flux rope
  properties obtained from the observational parameters that are evolved
  through the model to estimate the magnetic field vectors of ICMEs
  at any heliocentric distance. As a proof of concept, we present the
  case study of an Earth-impacting CME which occurred on 2013 April
  11. The predicted magnetic field profiles of the associated ICME
  show good agreement with those observed by the in-situ spacecraft. We
  further validated INFROS model for the ICMEs detected by the radially
  aligned multiple spacecraft orbiting the Sun at different heliocentric
  distances. The in-situ observations of those ICMEs as detected in
  MESSENGER at ∼ 0.3 AU or VEX at ~0.7 AU and STEREO at ~1 AU , help
  us to constrain the INFROS model parameters in order to predict the
  magnetic field-vectors of the ICME at 1 AU. INFROS shows promising
  results in the forecasting of Bz in near real-time. It is a simple less
  time-consuming and computationally inexpensive compared to other models
  and has the potential to be implemented as a practical space-weather
  forecasting tool.

---------------------------------------------------------
Title: Magnetic Field Strength in and Around Coronal Flux Ropes
Authors: Gopalswamy, Nat
2021cosp...43E1027G    Altcode:
  It is clear from observations and modeling perspectives that all
  interplanetary coronal mass ejections (ICMEs) may have a flux rope
  structure. At the Sun, flux ropes are inferred from post eruption
  arcades (PEAs), which are thought to be part staying with the Sun,
  while the other part, viz., the flux rope is ejected into space. The
  total reconnected flux can be derived from the magnetic flux underlying
  the PEA or the swept-up flare ribbon area. The reconnected flux
  has important quantitative information on the magnetic content of
  the ejected flux rope (the poloidal flux of the flux rope). This
  information, when coupled with the geometrical properties of the flux
  rope derived from white-light coronagraph images, can be used to derive
  the axial field strength of the flux rope near the Sun. Under the
  assumption of a force-free flux rope, one can get all the components
  of the flux rope magnetic field, including the one that causes
  geomagnetic storms. Coupled with the fact that the axial magnetic
  field direction can be obtained from a number of techniques, we have
  full information on the coronal flux ropes. The internal structure
  of the flux rope is key to predict its geoeffectiveness. The flux
  rope propagates through the ambient medium and often drives a shock
  if super-Alfvenic. Shock-driving CMEs have an additional source of
  southward magnetic field that can result in geomagnetic storms. The
  presence of a shock near the Sun can often be inferred from type
  II radio bursts and white-light observations. The white-light shock
  structure can be used to infer the ambient magnetic field strength
  because the shock standoff distance and the radius of curvature of the
  driving flux rope are related to the shock Mach number. Since the shock
  speed can be measured from coronagraph observations, it is possible
  to derive the ambient Alfven speed and magnetic field strength. This
  talk illustrates the techniques to derive the flux-rope and ambient
  field strengths with specific examples.

---------------------------------------------------------
Title: The COSPAR Capacity Building Workshops in Solar Terrestrial
    Science
Authors: Gopalswamy, Nat
2021cosp...43E2156G    Altcode:
  The main objective of COSPAR Capacity-Building Workshops (CBWs) is
  to train young scientists and students from developing countries in
  using space data obtained by current and past missions. The training
  involves accessing data from various sources and processing them using
  free software tools available online. The COSPAR CBW activities enhance
  the scientific return from many space missions by addressing problems
  that were not originally considered by the mission teams. For solar
  terrestrial science, there are several data bases dealing with solar
  variability and its terrestrial and heliospheric impact. For example,
  large arrays of data have been accumulated at the CDAW Data Center
  of NASA's Goddard Space Flight Center from missions such as the
  ESA/NASA Solar and Heliospheric Observatory (SOHO) mission, NASA's
  Solar Terrestrial Relations Observatory (STEREO), Wind, and Advanced
  Composition Explorer (ACE). There are uniform and extended data sets
  on solar flares and coronal mass ejections that have interesting
  implications for magnetic energy release on the Sun and societal
  implications for humans. There are many data sets from ground-based
  observations that complement the space data and help address many
  problems in solar terrestrial science. This talk summarizes my
  experience is serving as the science lead in a couple of workshops
  that focused on coronal mass ejections and their relation to shocks
  in the inner heliosphere.

---------------------------------------------------------
Title: Space Weather Capacity Building Activities by the International
    Space Weather Initiative
Authors: Gopalswamy, Nat
2021cosp...43E2435G    Altcode:
  The International Space Weather Initiative (ISWI) is a grassroots
  organization involved in creating and developing space-weather-literate
  communities around the globe. ISWI activities include deployment of
  space weather instrumentation, space weather science research, and
  capacity building. ISWI was formed to continue the International
  Heliophysical Year (IHY 2007) activities focusing on the space
  weather aspects in the near-Earth space. Since 2013, ISWI is aligned
  with the permanent space weather agenda of the Science and Technology
  Subcommittee (STSC) formed by the United Nations Committee on Peaceful
  Uses of Outer Space (UNCOPUOS). The governance of ISWI involves the
  secretariat and a steering committee constituted by experts from
  the space weather community. Information on ISWI activities and space
  weather in general is distributed via the ISWI Newsletter issued once a
  month. The ISWI web site (http://iswi-secretariat.org) is a repository
  of documents related to ISWI activities including ISWI instrument
  networks, lectures from schools, workshop presentations, and the ISWI
  Newsletter issues. The capacity building and educational activities
  of ISWI are (i) running space science schools, mainly in developing
  countries, (ii) deployment of space weather instruments around the
  world, and (iii) participating in efforts by other international
  organizations such as COSPAR. The space science schools involve teaching
  all topics from the solar interior to the surface of Earth to graduate
  students and young scientists. These schools are run in collaboration
  with other international organizations such as SCOSTEP and COSPAR
  that have overlapping interest in capacity building. The instrument
  deployment is also a capacity building activity because students are
  involved in the deployment and operations. The data from the space
  weather instruments are combined with data from other sources including
  space missions to address space weather problems. ISWI conducts space
  weather workshops in collaboration with the United Nations Office of
  Outer Space Affairs (UNOOSA) in which ISWI instrument providers and
  hosts attend to present their science results. Young scientists and
  students are provided with travel support to attend these workshops. The
  lecturers of ISWI schools/workshops often visit local high schools
  to interact with students and science teachers to inspire the next
  generation scientists.

---------------------------------------------------------
Title: Properties of High-Frequency Type II Radio Bursts and Their
    Relation to the Associated Coronal Mass Ejections
Authors: Umuhire, A. C.; Gopalswamy, N.; Uwamahoro, J.; Akiyama, S.;
   Yashiro, S.; Mäkelä, P.
2021SoPh..296...27U    Altcode:
  Solar radio bursts are often early indicators of space weather events
  such as coronal mass ejections (CMEs). In this study, we determined
  the properties of a sample of 40 high-starting-frequency (≥ 150 MHz)
  type II radio bursts and the characteristics of the associated CMEs
  such as width, location and speed during 2010-2016. The high starting
  frequency implies shock formation closer to the solar surface, which
  has important ramifications for the analysis of particle acceleration
  near the Sun. We found the CME heliocentric distances at the onset
  time of metric type II bursts range from 1.16 to 1.90 solar radii
  (Rs). The study was also extended to 128 metric type II bursts to
  include lower-starting-frequency events for further analysis. The
  projected CME heights range from 1.15 to 2.85 Rs. The lower starting
  frequency correspond to shocks forming at larger heights. A weak
  correlation was found between the type-II starting frequency and
  CME heights, which is consistent with the density decline in the
  inner corona. The analysis confirmed a good correlation between the
  drift rate and the starting frequency of type II bursts (correlation
  coefficient ∼ 0.8). Taking into account the radial variation of CMEs
  speeds from the inner corona to the interplanetary medium, we observed
  the deviations from the universal drift-rate spectrum of type II bursts
  and confirmed the previous results relating type II bursts to CMEs.

---------------------------------------------------------
Title: The impact of CMEs on the critical frequency of F2-layer
    ionosphere (foF2)
Authors: Seyoum, Alene; Gopalswamy, Nat; Nigussie, Melessew; Mezgebe,
   Nigusse
2021IAUS..356..400S    Altcode: 2020arXiv200408278S
  The ionospheric critical frequency (foF2) from ionosonde measurements
  at geographic high, middle, and low latitudes are analyzed with the
  occurrence of coronal mass ejections (CMEs) in long term variability
  of the solar cycles. We observed trends of monthly maximum foF2 values
  and monthly averaged values of CME parameters such as speed, angular
  width, mass, and kinetic energy with respect to time. The impact of CMEs
  on foF2 is very high at high latitudes and low at low latitudes. The
  time series for monthly maximum foF2 and monthly-averaged CME speed
  are moderately correlated at high and middle latitudes.

---------------------------------------------------------
Title: The Balloon-Borne Investigation of Temperature and Speed of
Electrons in the Corona (BITSE): Mission Description and Preliminary
    Results
Authors: Gopalswamy, N.; Newmark, J.; Yashiro, S.; Mäkelä, P.;
   Reginald, N.; Thakur, N.; Gong, Q.; Kim, Y. -H.; Cho, K. -S.; Choi,
   S. -H.; Baek, J. -H.; Bong, S. -C.; Yang, H. -S.; Park, J. -Y.; Kim,
   J. -H.; Park, Y. -D.; Lee, J. -O.; Kim, R. -S.; Lim, E. -K.
2021SoPh..296...15G    Altcode: 2020arXiv201106111G
  We report on the Balloon-borne Investigation of Temperature and Speed of
  Electrons in the corona (BITSE) mission launched recently to observe the
  solar corona from ≈3 Rs to 15 Rs at four wavelengths (393.5, 405.0,
  398.7, and 423.4 nm). The BITSE instrument is an externally occulted
  single stage coronagraph developed at NASA's Goddard Space Flight Center
  in collaboration with the Korea Astronomy and Space Science Institute
  (KASI). BITSE used a polarization camera that provided polarization
  and total brightness images of size 1024 ×1024 pixels. The Wallops
  Arc Second Pointer (WASP) system developed at NASA's Wallops Flight
  Facility (WFF) was used for Sun pointing. The coronagraph and WASP were
  mounted on a gondola provided by WFF and launched from the Fort Sumner,
  New Mexico station of Columbia Scientific Balloon Facility (CSBF) on
  September 18, 2019. BITSE obtained 17,060 coronal images at a float
  altitude of ≈128,000 feet (≈39 km) over a period of ≈4 hrs. BITSE
  flight software was based on NASA's core Flight System, which was
  designed to help develop flight quality software. We used EVTM (Ethernet
  Via Telemetry) to download science data during operations; all images
  were stored on board using flash storage. At the end of the mission,
  all data were recovered and analyzed. Preliminary analysis shows that
  BITSE imaged the solar minimum corona with the equatorial streamers
  on the east and west limbs. The narrow streamers observed by BITSE are
  in good agreement with the geometric properties obtained by the Solar
  and Heliospheric Observatory (SOHO) coronagraphs in the overlapping
  physical domain. In spite of the small signal-to-noise ratio (≈14 )
  we were able to obtain the temperature and flow speed of the western
  steamer. In the heliocentric distance range 4 - 7 Rs on the western
  streamer, we obtained a temperature of ≈1.0 ±0.3 MK and a flow
  speed of ≈260 km s<SUP>−1</SUP> with a large uncertainty interval.

---------------------------------------------------------
Title: Comparing Solar Minimum 24/25 with Historical Solar Wind
    Records at 1 AU
Authors: Jian, L.; Gopalswamy, N.; Luhmann, J. G.; Russell, C. T.
2020AGUFMSH021..04J    Altcode:
  Following the study of previous deep solar minimum 23/24 in Jian et
  al. (2011), we choose a one-year interval at each solar minimum from the
  beginning of the acquisition of solar wind measurements in the ecliptic
  plane and at 1 AU, to compare the solar and solar wind parameters at
  the most recent solar minimum 24/25 with previous solar minima. In
  addition, combining the continuous solar wind measurements near 1 AU
  from Wind/ACE and STEREO A/B missions, we survey and characterize
  the large-scale solar wind structures during 1995-2019, including
  slow-to-fast stream interaction regions (SIRs), interplanetary coronal
  mass ejections (ICMEs), and interplanetary shocks. We study their
  solar cycle variations comprehensively, focusing on the comparison
  of solar cycles 23 and 24, as well as the comparison of solar minima
  22/23, 23/24, and 24/25. Through the study, we describe the long-term
  variations of space environment for other WHPI investigations.

---------------------------------------------------------
Title: The Coronal Diagnostic Experiment (CODEX)
Authors: Newmark, J. S.; Gopalswamy, N.; Kim, Y. H.; Viall, N. M.;
   Cho, K. S. F.; Reginald, N. L.; Bong, S. C.; Gong, Q.; Choi, S.;
   Strachan, L.; Yashiro, S.
2020AGUFMSH0280011N    Altcode:
  Understanding solar wind sources and acceleration mechanisms
  is an overarching solar physics goal. Current models are highly
  under-constrained due to the limitations of the existing data,
  particularly in the ~3-10 Rs range. COronal Diagnostic EXperiment
  (CODEX) is designed to deliver the first global, comprehensive
  data sets that will impose crucial constraints and answer targeted
  essential questions, including: Are there signatures of hot plasma
  released into the solar wind from previously closed fields? What are
  the velocities and temperatures of the density structures that are
  observed so ubiquitously within streamers and coronal holes? <P />To
  provide these crucial measurements, NASA's Goddard Space Flight Center,
  in collaboration with the Korea Astronomy and Space Science Institute,
  will develop a next-generation coronagraph for the International
  Space Station. This imaging coronagraph uses multiple filters to obtain
  simultaneous measurements of electron density, temperature, and velocity
  within a single instrument. This will be the first time all three
  have been measured simultaneously for this critical field-of-view,
  and CODEX achieves these measurements multiple times a day.

---------------------------------------------------------
Title: Acceleration of &gt;300 MeV particles by interplanetary shocks
    evidenced by sustained gamma-ray emission from the Sun
Authors: Gopalswamy, N.; Makela, P.; Yashiro, S.; Akiyama, S.
2020AGUFMSH008..02G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Intercycle and Intracycle Variation of Halo CME Rate Obtained
    from SOHO/LASCO Observations
Authors: Dagnew, Fithanegest Kassa; Gopalswamy, Nat; Tessema, Solomon
   Belay; Akiyama, Sachiko; Yashiro, Seiji; Tesfu, Tesfay Yemane
2020ApJ...903..118D    Altcode:
  We report on the properties of halo coronal mass ejections (HCMEs)
  in solar cycles 23 and 24. We compare the HCME properties between the
  corresponding phases (rise, maximum, and declining) in cycles 23 and
  24 and compare those between the whole cycles. Despite the significant
  decline in the sunspot number (SSN) in cycle 24, which dropped by 46%
  with respect to cycle 23, the abundance of HCMEs is similar in the two
  cycles. The HCME rate per SSN is 44% higher in cycle 24. In the maximum
  phase, cycle 24 rate normalized to SSN increased by 127%, while the
  SSN dropped by 43%. The source longitudes of cycle 24 HCMEs are more
  uniformly distributed than those in cycle 23. We found that the average
  sky-plane speed in cycle 23 is ∼16% higher than that in cycle 24. The
  size distributions of the associated flares between the two cycles and
  the corresponding phases are similar. The average speed at a central
  meridian distance (CMD) ≥ 60<SUP>0</SUP> for cycle 23 is ∼28% higher
  than that of cycle 24. We discuss the unusual bump in HCME activity
  in the declining phase of cycle 23 as being due to exceptional active
  regions that produced many CMEs during 2003 October-2005 October. The
  differing HCME properties in the two cycles can be attributed to the
  anomalous expansion of cycle 24 CMEs. Considering the HCMEs in the
  rise, maximum, and declining phases, we find that the maximum phase
  shows the highest contrast between the two cycles.

---------------------------------------------------------
Title: Diffuse Interplanetary Radio Emission: Shock Emission or a
    Type III storm?
Authors: Gopalswamy, Nat; Akiyama, Sachiko; Mäkelä, Pertti;
   Yashiro, Seiji
2020URSL....2...49G    Altcode: 2020arXiv201112763G
  We present a clear case of a Diffuse Interplanetary Radio Emission
  (DIRE) event observed during 2002 March 11-12 in association with a
  fast coronal mass ejection (CME). In the previous event reported [1],
  there were two CMEs, and a detailed analysis was required to pin down
  the underlying CME. In the event presented here, the CME association
  is unambiguous, and the DIRE is found to originate from the flanks of
  the CME-driven shock. We also provide quantitative explanation for
  not observing radio emission from the shock nose. We also clarify
  that DIRE is not a type III storm because the latter occurs outside
  of solar eruptions.

---------------------------------------------------------
Title: The Energetic Particle Detector. Energetic particle instrument
    suite for the Solar Orbiter mission
Authors: Rodríguez-Pacheco, J.; Wimmer-Schweingruber, R. F.; Mason,
   G. M.; Ho, G. C.; Sánchez-Prieto, S.; Prieto, M.; Martín, C.;
   Seifert, H.; Andrews, G. B.; Kulkarni, S. R.; Panitzsch, L.; Boden,
   S.; Böttcher, S. I.; Cernuda, I.; Elftmann, R.; Espinosa Lara, F.;
   Gómez-Herrero, R.; Terasa, C.; Almena, J.; Begley, S.; Böhm, E.;
   Blanco, J. J.; Boogaerts, W.; Carrasco, A.; Castillo, R.; da Silva
   Fariña, A.; de Manuel González, V.; Drews, C.; Dupont, A. R.;
   Eldrum, S.; Gordillo, C.; Gutiérrez, O.; Haggerty, D. K.; Hayes,
   J. R.; Heber, B.; Hill, M. E.; Jüngling, M.; Kerem, S.; Knierim,
   V.; Köhler, J.; Kolbe, S.; Kulemzin, A.; Lario, D.; Lees, W. J.;
   Liang, S.; Martínez Hellín, A.; Meziat, D.; Montalvo, A.; Nelson,
   K. S.; Parra, P.; Paspirgilis, R.; Ravanbakhsh, A.; Richards, M.;
   Rodríguez-Polo, O.; Russu, A.; Sánchez, I.; Schlemm, C. E.; Schuster,
   B.; Seimetz, L.; Steinhagen, J.; Tammen, J.; Tyagi, K.; Varela, T.;
   Yedla, M.; Yu, J.; Agueda, N.; Aran, A.; Horbury, T. S.; Klecker, B.;
   Klein, K. -L.; Kontar, E.; Krucker, S.; Maksimovic, M.; Malandraki,
   O.; Owen, C. J.; Pacheco, D.; Sanahuja, B.; Vainio, R.; Connell,
   J. J.; Dalla, S.; Dröge, W.; Gevin, O.; Gopalswamy, N.; Kartavykh,
   Y. Y.; Kudela, K.; Limousin, O.; Makela, P.; Mann, G.; Önel, H.;
   Posner, A.; Ryan, J. M.; Soucek, J.; Hofmeister, S.; Vilmer, N.;
   Walsh, A. P.; Wang, L.; Wiedenbeck, M. E.; Wirth, K.; Zong, Q.
2020A&A...642A...7R    Altcode:
  After decades of observations of solar energetic particles from
  space-based observatories, relevant questions on particle injection,
  transport, and acceleration remain open. To address these scientific
  topics, accurate measurements of the particle properties in the inner
  heliosphere are needed. In this paper we describe the Energetic Particle
  Detector (EPD), an instrument suite that is part of the scientific
  payload aboard the Solar Orbiter mission. Solar Orbiter will approach
  the Sun as close as 0.28 au and will provide extra-ecliptic measurements
  beyond ∼30° heliographic latitude during the later stages of the
  mission. The EPD will measure electrons, protons, and heavy ions with
  high temporal resolution over a wide energy range, from suprathermal
  energies up to several hundreds of megaelectronvolts/nucleons. For
  this purpose, EPD is composed of four units: the SupraThermal
  Electrons and Protons (STEP), the Electron Proton Telescope (EPT),
  the Suprathermal Ion Spectrograph (SIS), and the High-Energy Telescope
  (HET) plus the Instrument Control Unit that serves as power and data
  interface with the spacecraft. The low-energy population of electrons
  and ions will be covered by STEP and EPT, while the high-energy
  range will be measured by HET. Elemental and isotopic ion composition
  measurements will be performed by SIS and HET, allowing full particle
  identification from a few kiloelectronvolts up to several hundreds
  of megaelectronvolts/nucleons. Angular information will be provided
  by the separate look directions from different sensor heads, on the
  ecliptic plane along the Parker spiral magnetic field both forward
  and backwards, and out of the ecliptic plane observing both northern
  and southern hemispheres. The unparalleled observations of EPD will
  provide key insights into long-open and crucial questions about the
  processes that govern energetic particles in the inner heliosphere.

---------------------------------------------------------
Title: A comparison of CME expansion speeds between solar cycles 23
    and 24
Authors: Dagnew, Fithanegest K.; Gopalswamy, Nat; Tessema, Solomon B.
2020JPhCS1620a2003D    Altcode:
  We report on a comparison of the expansion speeds of limb coronal mass
  ejections (CMEs) between solar cycles 23 and 24. We selected a large
  number of limb CME events associated with soft X-ray flare size greater
  than or equal to M1.0 from both cycles. We used data and measurement
  tools available at the online CME catalog (https://cdaw.gsfc.nasa.gov)
  that consists of the properties of all CMEs detected by the Solar
  and Heliospheric Observatory’s (SOHO) Large Angle and Spectrometric
  Coronagraph (LASCO). We found that the expansion speeds in cycle 24
  are higher than those in cycle 23. We also found that the relation
  between radial and expansion speeds has different slopes in cycles 23
  and 24. The cycle 24 slope is 45% higher than that in cycle 23. The
  expansion speed is also higher for a given radial speed. The difference
  increases with speed. For a 2000 km/s radial speed, the expansion
  speed in cycle 24 is ∼48% higher. These results present additional
  evidence for the anomalous expansion of cycle 24-CMEs, which is due
  to the reduced total pressure in the heliosphere.

---------------------------------------------------------
Title: Intercycle and intracycle variation of halo CME rate obtained
    from SOHO/LASCO observations
Authors: Kassa Dagnew, Fithanegest; Gopalswamy, Nat; Belay Tessema,
   Solomon; Akiyama, Sachiko; Yashiro, Seiji; Yemane Tesfu, Tesfay
2020arXiv200906033K    Altcode:
  We report on the properties of halo coronal mass ejections (HCMEs)
  in solar cycles 23 and 24. We compare the HCMEs properties between the
  corresponding phases (rise, maximum, and declining) in cycles 23 and
  24 in addition to comparing those between the whole cycles. Despite
  the significant decline in the sunspot number (SSN) in cycle 24, which
  dropped by 46% with respect to cycle 23, the abundance of HCMEs is
  similar in the two cycles. The HCME rate per SSN is 44% higher in cycle
  24. In the maximum phase, cycle-24 rate normalized to SSN increased by
  127% while the SSN dropped by 43%. The source longitudes of cycle-24
  HCMEs are more uniformly distributed than those in cycle 23. We found
  that the average sky-plane speed in cycle 23 is ~16% higher than that
  in cycle 24. The size distributions of the associated flares between
  the two cycles and the corresponding phases are similar. The average
  speed at a central meridian distance (CMD) = 600 for cycle 23 is ~28%
  higher than that of cycle 24. We discuss the unusual bump in HCME
  activity in the declining phase of cycle 23 as due to exceptional
  active regions that produced many CMEs during October 2003 to October
  2005. The differing HCME properties in the two cycles can be attributed
  to the anomalous expansion of cycle-24 CMEs. Considering the HCMEs
  in the rise, maximum and declining phases, we find that the maximum
  phase shows the highest contrast between the two cycles.

---------------------------------------------------------
Title: A catalog of prominence eruptions detected automatically in
    the SDO/AIA 304 Å images
Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.; Mäkelä, P. A.
2020JASTP.20505324Y    Altcode: 2020arXiv200511363Y
  We report on a statistical study of prominence eruptions (PEs) using
  a catalog of these events routinely imaged by the Atmospheric Imaging
  Assembly (AIA) on board the Solar Dynamics Observatory (SDO) in the
  304 Å pass band. Using an algorithm developed as part of an LWS
  project, we have detected PEs in 304 Å synoptic images with 2-min
  cadence since May 2010. A catalog of these PEs is made available
  online (https://cdaw.gsfc.nasa.gov/CME_list/autope/). The 304 Å
  images are polar-transformed and divided by a background map (pixels
  with minimum intensity during one day) to get the ratio maps above
  the limb. The prominence regions are defined as pixels with a ratio
  ≥2. Two prominence regions with more than 50% of pixels overlapping
  are considered the same prominence. If the height of a prominence
  increases monotonically in 5 successive images, it is considered
  eruptive. All the PEs seen above the limb are detected by the routine,
  but only PEs with width ≥15° are included in the catalog to eliminate
  polar jets and other small-scale mass motions. The identifications are
  also cross-checked with the PEs identified in Nobeyama Radioheliograph
  images (http://solar.nro.nao.ac.jp/norh/html/prominence/). The catalog
  gives the date, time, central position angle, latitude, and width of
  the eruptive prominence. The catalog also provides links to JavaScript
  movies that combine SDO/AIA images with GOES soft X-ray data to identify
  the associated flares, and with SOHO/LASCO C2 images to identify
  the associated coronal mass ejections. We examined the statistical
  properties of the PEs and found that (1) the surges generally occur only
  in the active region belt while prominences are found in all latitudes,
  and (2) the high-latitude PE speed decreased with the decreasing of
  the average polar magnetic field strength of the previous cycle.

---------------------------------------------------------
Title: Effect of the Weakened Heliosphere in Solar Cycle 24 on the
    Properties of Coronal Mass Ejections
Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.; Xie,
   H.; Mäkelä, P.
2020JPhCS1620a2005G    Altcode: 2020arXiv200708291G
  Solar cycle (SC) 24 has come to an end by the end of 2019, providing
  the opportunity to compare two full cycles to understand the
  manifestations of SC 24 - the smallest cycle in the Space Age that
  has resulted in a weak heliospheric state indicated by the reduced
  pressure. The backreaction of the heliospheric state is to make the
  coronal mass ejections (CMEs) appear physically bigger than in SC
  23, but their magnetic content has been diluted resulting in a lower
  geoeffectiveness. The heliospheric magnetic field is also lower in SC
  24, leading to the dearth of high-energy solar energetic particle (SEP)
  events. These space-weather events closely follow fast and wide (FW)
  CMEs. All but FW CMEs are higher in number in SC 24. The active region
  potential energy is lower in SC 24, consistent with the reduced rate
  of FW CMEs. The CME rate - sunspot number (SSN) correlation is high in
  both cycles but the rate increases faster in SC 24. We find that limb
  CMEs are slower in SC 24 as in the general population but wider. Limb
  halo CMEs also follow the same trend of slower SC-24 CMEs. However, the
  SC-24 CMEs become halos at a shorter distance from the Sun. Thus, slower
  CMEs becoming halos sooner is a clear indication of the backreaction
  of the weaker heliospheric state on CMEs. We can further pin down the
  heliospheric state as the reason for the altered CME properties because
  the associated flares have similar distributions in the two cycles -
  unaffected by the heliospheric state.

---------------------------------------------------------
Title: Interplanetary Radio Emission: A Summary of Recent Results
Authors: Gopalswamy, Nat
2020arXiv200809222G    Altcode:
  This paper summarizes some recent results in the low-frequency radio
  physics of the Sun. The spatial domain covers the space from the outer
  corona to the orbit of Earth. The results obtained make use of radio
  dynamic spectra and white-light coronagraph images and involve radio
  bursts associated with solar eruptions and those occurring outside solar
  eruptions. In particular, the connection between type II radio bursts
  and the sustained gamma-ray emission from the Sun is highlighted. The
  directivity of interplanetary type IV bursts found recently is discussed
  to understand the physical reason behind it. A new event showing the
  diffuse interplanetary radio emission (DIRE) is introduced and its
  properties are compared with those of regular type II bursts. The DIRE
  is from the flanks of a CME-driven shock propagating through nearby
  streamer. Finally, a new noise storm observed by two spacecraft is
  briefly discussed to highlight its evolution over two solar rotations
  including the disruption and recovery by solar eruptions.

---------------------------------------------------------
Title: The State of the Heliosphere Revealed by Limb-halo Coronal
    Mass Ejections in Solar Cycles 23 and 24
Authors: Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji
2020ApJ...897L...1G    Altcode: 2020arXiv200605844G
  We compare the properties of halo coronal mass ejections (CMEs)
  that originate close to the limb (within a central meridian distance
  range of 60°-∼90°) during solar cycles 23 and 24 to quantify the
  effect of the heliospheric state on CME properties. There are 44 and
  38 limb halos in cycles 23 and 24, respectively. Normalized to the
  cycle-averaged total sunspot number, there are 42% more limb halos in
  cycle 24. Although the limb halos as a population are very fast (average
  speed ∼1464 km s<SUP>-1</SUP>), cycle-24 halos are slower by ∼26%
  than the cycle-23 halos. We introduce a new parameter, the heliocentric
  distance of the CME leading edge at the time a CME becomes a full halo;
  this height is significantly shorter in cycle 24 (by ∼20%) and has
  a lower cutoff at ∼6 R<SUB>s</SUB>. These results show that cycle-24
  CMEs become halos sooner and at a lower speed than the cycle-23 ones. On
  the other hand, the flare sizes are very similar in the two cycles,
  ruling out the possibility of eruption characteristics contributing
  to the differing CME properties. In summary, this study reveals the
  effect of the reduced total pressure in the heliosphere that allows
  cycle-24 CMEs to expand more and become halos sooner than in cycle
  23. Our findings have important implications for the space-weather
  consequences of CMEs in cycle 25 (predicted to be similar to cycle 24)
  and for understanding the disparity in halo counts reported by automatic
  and manual catalogs.

---------------------------------------------------------
Title: A comparison of CME expansion speeds between solar cycles 23
    and 24
Authors: Kassa Dagnew, Fithanegest; Gopalswamy, Nat; Belay Tessema,
   Solomon
2020arXiv200713204K    Altcode:
  We report on a comparison of the expansion speeds of limb coronal mass
  ejections (CMEs) between solar cycles 23 and 24. We selected a large
  number of limb CME events associated with soft X-ray flare size greater
  than or equal to M1.0 from both cycles. We used data and measurement
  tools available at the online CME catalog (https://cdaw.gsfc.nasa.gov)
  that consists of the properties of all CMEs detected by the Solar
  and Heliospheric Observatory's (SOHO) Large Angle and Spectrometric
  Coronagraph (LASCO). We found that the expansion speeds in cycle 24
  are higher than those in cycle 23. We also found that the relation
  between radial and expansion speeds has different slopes in cycles 23
  and 24. The cycle 24 slope is 45% higher than that in cycle 23. The
  expansion speed is also higher for a given radial speed. The difference
  increases with speed. For a 2000 km/s radial speed, the expansion
  speed in cycle 24 is ~48% higher. These results present additional
  evidence for the anomalous expansion of cycle 24-CMEs, which is due
  to the reduced total pressure in the heliosphere.

---------------------------------------------------------
Title: Interplanetary shocks as a source of sustained gamma-ray
    emission from the Sun
Authors: Gopalswamy, Nat; Mäkelä, Pertti
2020EGUGA..2221334G    Altcode:
  It has recently been shown that the sustained gamma-ray emission
  (SGRE) from the Sun that lasts for hours beyond the impulsive phase
  of the associated flare is closely related to radio emission from
  interplanetary shocks (Gopalswamy et al. 2019, JPhCS, 1332, 012004,
  2019). This relationship supports the idea that &gt;300 MeV protons
  accelerated by CME-driven shocks propagate toward the Sun, collide
  with chromospheric protons and produce neutral pions that promptly
  decay into &gt;80 MeV gamma-rays. There have been two challenges
  to this idea. (i) Since the location of the shock can be halfway
  between the Sun and Earth at the SGRE end time, it has been suggested
  that magnetic mirroring will not allow the high energy protons to
  precipitate. (ii) Lack of correlation between the number protons
  involved in the production of &gt;100 MeV gamma-rays (Ng) and the
  number of protons (Nsep) in the associated solar energetic particle
  (SEP) event has been reported. In this paper, we show that the mirror
  ratio problem is no different from that in flare loops where electrons
  and protons precipitate to produce impulsive phase emissions. We also
  suggest that the lack of Ng - Nsep correlation is due to two reasons:
  (1) Nsep is underestimated in the case of eruptions happening at large
  ecliptic latitudes because the high-energy protons accelerated near
  the nose do not reach the observer. (2) In the case of limb events,
  the Ng is underestimated because gamma-rays from some part of the
  extended gamma-ray source do not reach the observer.

---------------------------------------------------------
Title: A Modified Spheromak Model Suitable for Coronal Mass Ejection
    Simulations
Authors: Singh, Talwinder; Yalim, Mehmet S.; Pogorelov, Nikolai V.;
   Gopalswamy, Nat
2020ApJ...894...49S    Altcode: 2020arXiv200210409S
  Coronal mass ejections (CMEs) are some of the primary drivers of
  extreme space weather. They are large eruptions of mass and magnetic
  field from the solar corona and can travel the distance between Sun
  and Earth in half a day to a few days. Predictions of CMEs at 1 au,
  in terms of both its arrival time and magnetic field configuration,
  are very important for predicting space weather. Magnetohydrodynamic
  modeling of CMEs, using flux rope-based models, is a promising tool
  for achieving this goal. In this study, we present one such model for
  CME simulations, based on spheromak magnetic field configuration. We
  have modified the spheromak solution to allow for independent input
  of poloidal and toroidal fluxes. The motivation for this is the
  possibility of estimating these fluxes from solar magnetograms and
  extreme ultraviolet data from a number of different approaches. We
  estimate the poloidal flux of CME using post-eruption arcades and
  toroidal flux from the coronal dimming. In this modified spheromak,
  we also have the option to control the helicity sign of flux ropes,
  which can be derived from the solar disk magnetograms using the
  magnetic tongue approach. We demonstrate the applicability of this
  model by simulating the 2012 July 12 CME in the solar corona.

---------------------------------------------------------
Title: Positron Processes in the Sun
Authors: Gopalswamy, Nat
2020Atoms...8...14G    Altcode: 2020arXiv200404280G
  Positrons play a major role in the emission of solar gamma-rays at
  energies from a few hundred keV to &gt;1 GeV. Although the processes
  leading to positron production in the solar atmosphere are well
  known, the origin of the underlying energetic particles that interact
  with the ambient particles is poorly understood. With the aim of
  understanding the full gamma-ray spectrum of the Sun, I review the
  key emission mechanisms that contribute to the observed gamma-ray
  spectrum, focusing on the ones involving positrons. In particular, I
  review the processes involved in the 0.511 MeV positron annihilation
  line and the positronium continuum emissions at low energies, and
  the pion continuum emission at high energies in solar eruptions. It
  is thought that particles accelerated at the flare reconnection and
  at the shock driven by coronal mass ejections are responsible for
  the observed gamma-ray features. Based on some recent developments I
  suggest that energetic particles from both mechanisms may contribute
  to the observed gamma-ray spectrum in the impulsive phase, while the
  shock mechanism is responsible for the extended phase.

---------------------------------------------------------
Title: Impact of space weather on climate and habitability of
    terrestrial-type exoplanets
Authors: Airapetian, V. S.; Barnes, R.; Cohen, O.; Collinson,
   G. A.; Danchi, W. C.; Dong, C. F.; Del Genio, A. D.; France, K.;
   Garcia-Sage, K.; Glocer, A.; Gopalswamy, N.; Grenfell, J. L.; Gronoff,
   G.; Güdel, M.; Herbst, K.; Henning, W. G.; Jackman, C. H.; Jin, M.;
   Johnstone, C. P.; Kaltenegger, L.; Kay, C. D.; Kobayashi, K.; Kuang,
   W.; Li, G.; Lynch, B. J.; Lüftinger, T.; Luhmann, J. G.; Maehara, H.;
   Mlynczak, M. G.; Notsu, Y.; Osten, R. A.; Ramirez, R. M.; Rugheimer,
   S.; Scheucher, M.; Schlieder, J. E.; Shibata, K.; Sousa-Silva, C.;
   Stamenković, V.; Strangeway, R. J.; Usmanov, A. V.; Vergados, P.;
   Verkhoglyadova, O. P.; Vidotto, A. A.; Voytek, M.; Way, M. J.; Zank,
   G. P.; Yamashiki, Y.
2020IJAsB..19..136A    Altcode: 2019arXiv190505093A
  The current progress in the detection of terrestrial type exoplanets has
  opened a new avenue in the characterization of exoplanetary atmospheres
  and in the search for biosignatures of life with the upcoming
  ground-based and space missions. To specify the conditions favorable for
  the origin, development and sustainment of life as we know it in other
  worlds, we need to understand the nature of astrospheric, atmospheric
  and surface environments of exoplanets in habitable zones around
  G-K-M dwarfs including our young Sun. Global environment is formed by
  propagated disturbances from the planet-hosting stars in the form of
  stellar flares, coronal mass ejections, energetic particles, and winds
  collectively known as astrospheric space weather. Its characterization
  will help in understanding how an exoplanetary ecosystem interacts
  with its host star, as well as in the specification of the physical,
  chemical and biochemical conditions that can create favorable and/or
  detrimental conditions for planetary climate and habitability along with
  evolution of planetary internal dynamics over geological timescales. A
  key linkage of (astro) physical, chemical, and geological processes can
  only be understood in the framework of interdisciplinary studies with
  the incorporation of progress in heliophysics, astrophysics, planetary
  and Earth sciences. The assessment of the impacts of host stars on the
  climate and habitability of terrestrial (exo)planets will significantly
  expand the current definition of the habitable zone to the biogenic zone
  and provide new observational strategies for searching for signatures
  of life. The major goal of this paper is to describe and discuss the
  current status and recent progress in this interdisciplinary field and
  to provide a new roadmap for the future development of the emerging
  field of exoplanetary science and astrobiology.

---------------------------------------------------------
Title: ICME Evolution in the Inner Heliosphere
Authors: Luhmann, J. G.; Gopalswamy, N.; Jian, L. K.; Lugaz, N.
2020SoPh..295...61L    Altcode:
  ICMEs (interplanetary coronal mass ejections), the heliospheric
  counterparts of what is observed with coronagraphs at the Sun as CMEs,
  have been the subject of intense interest since their close association
  with geomagnetic storms was established in the 1980s. These major
  interplanetary plasma and magnetic field transients, often preceded
  and accompanied by solar energetic particles (SEPs), interact with
  planetary magnetospheres, ionospheres, and upper atmospheres in
  now fairly well-understood ways, although their details and context
  affect their overall impacts. The term ICME as it is used here refers
  to the complete solar-wind plasma and field disturbance, including the
  leading shock (if present), the compressed, deflected solar-wind plasma
  and the field behind the shock ("sheath"), and the coronal ejecta (the
  "driver") - often called a magnetic cloud. Many uncertainties remain in
  understanding both the relationship to what is observed at the Sun and
  the variety of local outcomes suggested by in-situ observations. This
  impacts our abilities to interpret events and to forecast effects based
  on solar observations. Here, we briefly consider what is known about
  ICMEs and their evolution en route from the Sun from the combination of
  available observations and interpretive models that have been developed
  up to now. The included references are only representative of the large
  body of work that has been published on this subject. Our aim is to
  provide the reader with an updated synthesis of research results in
  this still active area of heliophysics at the dawn of the Parker Solar
  Probe (PSP) and Solar Orbiter (SO) mission era.

---------------------------------------------------------
Title: Space, time and velocity association of successive coronal
    mass ejections
Authors: Lara, Alejandro; Gopalswamy, Nat; Niembro, Tatiana;
   Pérez-Enríquez, Román; Yashiro, Seiji
2020A&A...635A.112L    Altcode:
  <BR /> Aims: Our aim is to investigate the possible physical association
  between consecutive coronal mass ejections (CMEs). <BR /> Methods:
  Through a statistical study of the main characteristics of 27 761 CMEs
  observed by SOHO/LASCO during the past 20 years. <BR /> Results: We
  found the waiting time (WT) or time elapsed between two consecutive
  CMEs is &lt; 5 h for 59% and &lt; 25 h for 97% of the events, and
  the CME WTs follow a Pareto Type IV statistical distribution. The
  difference of the position-angle of a considerable population of
  consecutive CME pairs is less than 30°, indicating the possibility
  that their source locations are in the same region. The difference
  between the speed of trailing and leading consecutive CMEs follows a
  generalized Student t-distribution. The fact that the WT and the speed
  difference have heavy-tailed distributions along with a detrended
  fluctuation analysis shows that the CME process has a long-range
  dependence. As a consequence of the long-range dependence, we found
  a small but significative difference between the speed of consecutive
  CMEs, with the speed of the trailing CME being higher than the speed
  of the leading CME. The difference is largest for WTs &lt; 2 h and
  tends to be zero for WTs &gt; 10 h, and it is more evident during the
  ascending and descending phases of the solar cycle. We suggest that
  this difference may be caused by a drag force acting over CMEs closely
  related in space and time. <BR /> Conclusions: Our results show that
  the initiation and early propagation of a significant population of
  CMEs cannot be considered as a "pure" stochastic process; instead they
  have temporal, spatial, and velocity relationship.

---------------------------------------------------------
Title: Source of Energetic Protons in the 2014 September 1 Sustained
    Gamma-ray Emission Event
Authors: Gopalswamy, N.; Mäkelä, P.; Yashiro, S.; Akiyama, S.; Xie,
   H.; Thakur, N.
2020SoPh..295...18G    Altcode: 2020arXiv200103816G
  We report on the source of &gt;300 MeV protons during the SOL2014-09-01
  sustained gamma-ray emission (SGRE) event based on multi-wavelength data
  from a wide array of space- and ground-based instruments. Based on the
  eruption geometry we provide concrete explanation for the spatially and
  temporally extended γ -ray emission from the eruption. We show that
  the associated flux rope is of low inclination (roughly oriented in
  the east-west direction), which enables the associated shock to extend
  to the frontside. We compare the centroid of the SGRE source with the
  location of the flux rope's leg to infer that the high-energy protons
  must be precipitating between the flux rope leg and the shock front. The
  durations of the SOL2014-09-01 SGRE event and the type II radio burst
  agree with the linear relationship between these parameters obtained
  for other SGRE events with duration ≥3 hrs. The fluence spectrum of
  the SEP event is very hard, indicating the presence of high-energy
  (GeV) particles in this event. This is further confirmed by the
  presence of an energetic coronal mass ejection with a speed &gt;2000
  kms−<SUP>1</SUP>, similar to those in ground level enhancement (GLE)
  events. The type II radio burst had emission components from metric to
  kilometric wavelengths as in events associated with GLE events. All
  these factors indicate that the high-energy particles from the shock
  were in sufficient numbers needed for the production of γ -rays via
  neutral pion decay.

---------------------------------------------------------
Title: A Study of the Observational Properties of Coronal Mass
    Ejection Flux Ropes near the Sun
Authors: Sindhuja, G.; Gopalswamy, N.
2020ApJ...889..104S    Altcode:
  We present the observational properties of coronal mass ejection
  (CME) flux ropes (FRs) near the Sun based on a set of 35 events from
  solar cycle 24 (2010-2017). We derived the CME FR properties using the
  Flux Rope from Eruption Data technique. According to this technique,
  the geometrical properties are obtained from a flux-rope fit to CMEs
  and the magnetic properties from the reconnected flux in the source
  region. In addition, we use the magnetic flux in the dimming region
  at the eruption site. Geometric properties like radius of the FR and
  the aspect ratio are derived from the FR fitting. The reconnected
  flux exhibits a positive correlation with flare fluence in soft
  X-rays (SXRs), peak flare intensity in SXRs, CME speed, and kinetic
  energy, with correlation coefficients (cc) 0.78, 0.6, 0.48, and 0.55,
  respectively. We found a moderate positive correlation between magnetic
  flux in the core dimming regions and the toroidal flux obtained from
  the Lundquist solution for a force-free FR (cc = 0.43). Furthermore,
  we correlate the core dimming flux and CME mass (cc = 0.34). The area
  of the core dimming region shows a moderate correlation with the radius
  of the FR (cc = 0.4). Thus, we infer that greater magnetic content
  (poloidal and toroidal fluxes) indicates a more energetic eruption in
  terms of flare size, CME speed, kinetic energy, mass, and radius of
  the FR, suggesting important implications for space weather predictions.

---------------------------------------------------------
Title: The shock driving capability of a CME inferred from
    multiwavelength observations
Authors: Kassa Dagnew, Fithanegest; Gopalswamy, Nat; Belay Tessema,
   Solomon; Umuhire, Ange Cynthia; Yashiro, Seiji; Mäkelä, Pertti;
   Xie, Hong
2020arXiv200204056K    Altcode:
  The radial speed of a coronal mass ejection (CME) determines the
  shock-driving capability of a CME as indicated by the presence of a
  type II radio burst. Here we report on the April 18, 2014 CME that was
  associated with a type II radio burst in the metric and interplanetary
  domains. We used the radio-burst data provided by the San Vito Solar
  Observatory of the Radio Solar Telescope Network and data from the
  Wind spacecraft. The CME is a full halo in the field of view of
  the coronagraphs on board the Solar and Heliospheric Observatory
  (SOHO). The CME was also observed by the coronagraphs on board the
  Solar Terrestrial Relations Observatory (STEREO). We computed the CME
  shock and flux rope speeds based on the multi-view observations by the
  different coronagraphs and by EUV instruments. We determined the shock
  speed from metric and interplanetary radio observations and found them
  to be consistent with white-light observations, provided the metric type
  II burst and its continuation into the decameter-hectometric domain are
  produced at the shock flanks, where the speed is still high enough to
  accelerate electrons that produce the type II bursts. Interestingly,
  there was an interplanetary type II burst segment consistent with an
  origin at the shock nose suggesting that the curved shock was crossing
  plasma levels separated by a few solar radii. We conclude that the
  CME speed is high enough to produce the interplanetary Type II burst
  and a solar energetic particle (SEP) event. However, the speed is
  not high enough to produce a ground level enhancement (GLE) event,
  which requires the shock to form at a height of ~1.5 Rs.

---------------------------------------------------------
Title: An Observationally Constrained Analytical Model for Predicting
    the Magnetic Field Vectors of Interplanetary Coronal Mass Ejections
    at 1 au
Authors: Sarkar, Ranadeep; Gopalswamy, Nat; Srivastava, Nandita
2020ApJ...888..121S    Altcode: 2019arXiv191203494S
  We report on an observationally constrained analytical model, the
  INterplanetary Flux ROpe Simulator (INFROS), for predicting the magnetic
  field vectors of coronal mass ejections (CMEs) in the interplanetary
  medium. The main architecture of INFROS involves using the near-Sun
  flux rope properties obtained from the observational parameters that
  are evolved through the model in order to estimate the magnetic field
  vectors of interplanetary CMEs (ICMEs) at any heliocentric distance. We
  have formulated a new approach in INFROS to incorporate the expanding
  nature and the time-varying axial magnetic field strength of the flux
  rope during its passage over the spacecraft. As a proof of concept,
  we present the case study of an Earth-impacting CME which occurred on
  2013 April 11. Using the near-Sun properties of the CME flux rope,
  we have estimated the magnetic vectors of the ICME as intersected
  by the spacecraft at 1 au. The predicted magnetic field profiles
  of the ICME show good agreement with those observed by the in situ
  spacecraft. Importantly, the maximum strength (10.5 ± 2.5 nT) of the
  southward component of the magnetic field (Bz) obtained from the model
  prediction is in agreement with the observed value (11 nT). Although our
  model does not include the prediction of the ICME plasma parameters, as
  a first-order approximation, it shows promising results in forecasting
  of Bz in near real time, which is critical for predicting the severity
  of the associated geomagnetic storms. This could prove to be a simple
  space-weather forecasting tool compared to the time-consuming and
  computationally expensive MHD models.

---------------------------------------------------------
Title: On the properties of solar energetic particle events associated
    with metric type II radio bursts
Authors: Mäkelä, Pertti; Gopalswamy, Nat; Xie, Hong; Akiyama,
   Sachiko; Yashiro, Seiji; Thakur, Neeharika
2020arXiv200110506M    Altcode:
  Metric type II solar radio bursts and solar energetic particles (SEPs)
  are both associated with shock fronts driven by coronal mass ejections
  (CMEs) in the solar corona. Recent studies of ground level enhancements
  (GLEs), regular large solar energetic particle (SEP) events and filament
  eruption (FE) associated large SEP events have shown that SEP events are
  organized by spectral index of proton fluence spectra and by the average
  starting frequencies of the associated type II radio bursts. Both these
  results indicate a hierarchical relationship between CME kinematics
  and SEP event properties. In this study, we expand the investigations
  to fluence spectra and the longitudinal extent of metric type II
  associated SEP events including low-intensity SEP events. We utilize
  SEP measurements of particle instruments on the Solar and Heliospheric
  Observatory (SOHO) and Solar Terrestrial Relations Observatory (STEREO)
  spacecraft together with radio bursts observations by ground-based
  radio observatories during solar cycle 24. Our results show that
  low-intensity SEP events follow the hierarchy of spectral index or
  the hierarchy of the starting frequency of type II radio bursts. We
  also find indications of a trend between the onset frequency of metric
  type II bursts and the estimated longitudinal extent of the SEP events
  although the scatter of data points is quite large. These two results
  strongly support the idea of SEP acceleration by shocks. Stronger
  shocks develop closer to the Sun.

---------------------------------------------------------
Title: The Shock-Driving Capability of a CME Inferred from
    Multiwavelength Observations
Authors: Dagnew, F.; Gopalswamy, N.; Tessema, S.; Umuhire, A.; Yashiro,
   S.; Mäkelä, P.; Xie, H.
2019SunGe..14..105D    Altcode: 2019SunGe..14...105
  The radial speed of a coronal mass ejection (CME) determines the
  shock-driving capability of a CME as indicated by the presence of a
  type II radio burst. Here we report on the April 18, 2014 CME that was
  associated with a type II radio burst in the metric and interplanetary
  domains. We used the radio-burst data provided by the San Vito Solar
  Observatory of the Radio Solar Telescope Network and data from the
  Wind spacecraft. The CME is a full halo in the field of view of
  the coronagraphs on board the Solar and Heliospheric Observatory
  (SOHO). The CME was also observed by the coronagraphs on board the
  Solar Terrestrial Relations Observatory (STEREO). We computed the CME
  shock and flux rope speeds based on the multi-view observations by the
  different coronagraphs and by EUV instruments. We determined the shock
  speed from metric and interplanetary radio observations and found them
  to be consistent with white-light observations, provided the metric type
  II burst and its continuation into the decameter-hectometric domain are
  produced at the shock flanks, where the speed is still high enough to
  accelerate electrons that produce the type II bursts. Interestingly,
  there was an interplanetary type II burst segment consistent with an
  origin at the shock nose suggesting that the curved shock was crossing
  plasma levels separated by a few solar radii. We conclude that the
  CME speed is high enough to produce the interplanetary Type II burst
  and a solar energetic particle (SEP) event. However, the speed is
  not high enough to produce a ground level enhancement (GLE) event,
  which requires the shock to form at a height of ~1.5 Rs.

---------------------------------------------------------
Title: Low Frequency Radio Bursts Observed by the Wind Spacecraft
    and their Contribution to the Understanding of Coronal Mass Ejections
Authors: Gopalswamy, N.; Makela, P.; Yashiro, S.
2019AGUFMSH43C3379G    Altcode:
  At frequencies below the ionospheric cutoff, only three types of solar
  radio bursts caused by nonthermal electrons are observed: type II,
  type III, and type IV bursts. A quarter century of radio observations
  from the Radio and Plasma Wave (WAVES) experiment and white light
  observations from the Large Angle and Spectrometric Coronagraph
  (LASCO) have contributed enormously to our understanding of solar
  eruptions and their heliospheric consequences. In particular, type II
  bursts provide information on shocks driven by coronal mass ejections
  (CMEs), including the locations of particle acceleration along the
  shock surface and their ability to identify shocks accelerating solar
  energetic particle (SEP) events. The ending frequencies of type II
  bursts have become an important indicator of the heliocentric distance
  over which shocks remain as efficient particle accelerators evidenced
  by high-energy SEP events and sustained gamma-ray emission (SGRE)
  events. This paper highlights some major results regarding CMEs and
  low-frequency radio bursts and summarize some outstanding problems
  that are being investigated.

---------------------------------------------------------
Title: Solar Sources of Coronal Mass Ejections
Authors: Akiyama, S.; Gopalswamy, N.; Yashiro, S.; Michalek, G.
2019AGUFMSH11D3389A    Altcode:
  Coronal Mass Ejections (CMEs) are one of the important phenomena
  in space weather research. The SOHO/LASCO CME catalog has listed
  more than 29,000 CMEs since January 1996 and is extensively used in
  the community. The catalog provides the basic CME properties, e.g.,
  speed, angular width, mass, and kinetic energy. However the CME source
  information is not included since it is difficult to examine the source
  of all CMEs listed in the CME catalog. Here we describe two special
  CME lists that include CME source information: (i) a list of wide CMEs
  whose angular width is ≥ 60⁰, and (ii) list of CMEs associated
  with ≥ C3.0 flares. To determine the source location, we use all
  available eruptive signatures near the surface, such as solar flares,
  filament eruptions, EUV waves, and coronal dimmings. The X-ray flare
  class and the flare start/peak times are also listed if available. We
  have assigned six confidence levels to the source identification:
  0 - no source was identified, 5 - source was identified without
  doubt. We were able to identify the source locations of 6,870 wide
  CMEs out of 8,420 that occurred during 1996 to 2018. We found that 48%
  of wide CMEs originated from the active regions and 52% were from the
  quiet Sun. Solar flares and CMEs are closely related but there is no
  one-to-one correspondence. During 1996 to 2018, there are 7,658 ≥
  C3 flares. From these, we find that ~90% of X-class, 50% of M-class,
  and 20% of C3-C9 class flares were associated with CMEs. Statistical
  relationship between the flares and the CMEs will be presented.

---------------------------------------------------------
Title: On the Shock Source of Sustained Gamma-Ray Emission from
    the Sun
Authors: Gopalswamy, N.; Mäkelä, P.; Yashiro, S.; Lara, A.; Akiyama,
   S.; Xie, H.
2019JPhCS1332a2004G    Altcode: 2019arXiv190713318G
  It has recently been shown that the spatially and temporally extended
  γ-ray emission in solar eruptions are caused by &gt;300 MeV protons
  precipitating on the Sun from shocks driven by coronal mass ejections
  (CMEs). The γ-rays result from the decay of neutral pions produced
  in the proton-proton interaction when the &gt;300 MeV protons collide
  with those in the chromosphere. The evidence comes from the close
  correlation between the durations of the sustained gamma-ray emission
  (SGRE) and the associated interplanetary (IP) type II radio bursts. In
  this paper, we provide further evidence that support the idea that
  protons accelerated in IP shocks driven by CMEs propagate toward the
  Sun, precipitate in the chromosphere to produce the observed SGRE. We
  present the statistical properties of the SGRE events and the associated
  CMEs, flares, and type II radio bursts. It is found that the SGRE
  CMEs are similar to those associated with ground level enhancement
  events. The CME speed is well correlated with the SGRE fluence. High
  CME speed is an important requirement for the occurrence of SGRE,
  while the flare size is not. Based on these results, we present a
  schematic model illustrating the spatially and temporally extended
  nature of SGRE related to the CME flux rope-shock structure.

---------------------------------------------------------
Title: Statistical Survey of Coronal Mass Ejections and Interplanetary
    Type II Bursts
Authors: Krupar, V.; Magdalenić, J.; Eastwood, J. P.; Gopalswamy,
   N.; Kruparova, O.; Szabo, A.; Němec, F.
2019ApJ...882...92K    Altcode:
  Coronal mass ejections (CMEs) are responsible for most severe
  space weather events, such as solar energetic particle events and
  geomagnetic storms at Earth. Type II radio bursts are slow drifting
  emissions produced by beams of suprathermal electrons accelerated at
  CME-driven shock waves propagating through the corona and interplanetary
  medium. Here, we report a statistical study of 153 interplanetary
  type II radio bursts observed by the two STEREO spacecraft between
  2008 March and 2014 August. The shock associated radio emission was
  compared with CME parameters included in the Heliospheric Cataloguing,
  Analysis and Techniques Service catalog. We found that faster CMEs
  are statistically more likely to be associated with the interplanetary
  type II radio bursts. We correlate frequency drifts of interplanetary
  type II bursts with white-light observations to localize radio sources
  with respect to CMEs. Our results suggest that interplanetary type II
  bursts are more likely to have a source region situated closer to CME
  flanks than CME leading edge regions.

---------------------------------------------------------
Title: Are Solar Energetic Particle Events and Type II Bursts
    Associated with Fast and Narrow Coronal Mass Ejections?
Authors: Kahler, S. W.; Ling, A. G.; Gopalswamy, N.
2019SoPh..294..134K    Altcode:
  Gradual solar energetic (E &gt;10 MeV) particle (SEP) events and
  metric through kilometric wavelength type II radio bursts are usually
  associated with shocks driven by fast (V ≥900 kms−<SUP>1</SUP>)
  and wide (W ≥60<SUP>∘</SUP>) coronal mass ejections (FW CMEs). This
  criterion was established empirically by several studies from solar
  cycle 23. The characteristic Alfvén speed in the corona, which ranges
  over 500 - 1500 km s<SUP>−1</SUP> at heights ≥2 R<SUB>o</SUB>,
  provides the minimum V requirement for a CME to drive a shock, but the
  general absence of SEP events or type II bursts with fast and narrow
  (W &lt;60<SUP>∘</SUP>) CMEs has not been explained. We review and
  confirm the earlier studies with a more comprehensive comparison of SEP
  events and type II bursts with fast and narrow (FN) CMEs. We offer an
  explanation for the lack of SEP event and type II burst associations
  with FN CMEs in terms of recent heuristic arguments and modeling that
  show that the response of a magnetized plasma to the propagation of
  a CME depends on the CME geometry as well as on its speed. A clear
  distinction is made between a projectile that propagates through
  the medium to produce a bow shock, and a 3D piston that everywhere
  accumulates material to produce a broad shock and sheath. The bow
  shock is unfavorable for producing SEP events and type II bursts,
  but the 60<SUP>∘</SUP> cut-off is not explained.

---------------------------------------------------------
Title: Statistical Study on Multispacecraft Widespread Solar Energetic
    Particle Events During Solar Cycle 24
Authors: Xie, H.; St. Cyr, O. C.; Mäkelä, P.; Gopalswamy, N.
2019JGRA..124.6384X    Altcode:
  We conduct a statistical study on the large three-spacecraft widespread
  solar energetic particle (SEP) events. Longitudinal distributions
  of the peak intensities, onset delays, and relation between the SEP
  intensity, coronal mass ejection (CME) shock speed, width, and the
  kinetic energy of the CME have been investigated. We apply a Gaussian
  fit to obtain the SEP intensity I<SUB>0</SUB> and distribution width
  σ and a forward-modeling fit to determine the true shock speed and
  true CME width. We found a good correlation between σ and connection
  angle to the flare site and I<SUB>0</SUB> and the kinetic energy
  of the CME. By including the true shock speed and true CME widths,
  we reduce root-mean-square errors on the predicted SEP intensity
  by ∼41% for protons compared to Richardson et al.'s (2014, <A
  href="https://doi.org/10.1007/s11207-014-0524-8">https://doi.org/10.1007/s11207-014-0524-8</A>)
  prediction. The improved correlation between the CME kinetic energy and
  SEP intensity provides strong evidence for the CME-shock acceleration
  theory of SEPs. In addition, we found that electron and proton release
  time delays (DTs) relative to Type II radio bursts increase with
  connection angles. The average electron (proton) DT is ∼14 (32)
  min for strongly anisotropic events and ∼2.5 (4.4) hr for weakly
  anisotropic events. Poor magnetic connectivity and large scattering
  effects are two main reasons to cause large delays.

---------------------------------------------------------
Title: Direct Estimates of the Solar Coronal Magnetic Field
    Using Contemporaneous Extreme-ultraviolet, Radio, and White-light
    Observations
Authors: Kumari, Anshu; Ramesh, R.; Kathiravan, C.; Wang, T. J.;
   Gopalswamy, N.
2019ApJ...881...24K    Altcode: 2019arXiv190709721K
  We report a solar coronal split-band type II radio burst
  that was observed on 2016 March 16 with the Gauribidanur Radio
  Spectro-Polarimeter in the frequency range ≈90-50 MHz, and the
  Gauribidanur RadioheliograPH at two discrete frequencies, viz. 80 and
  53.3 MHz. Observations around the same epoch in extreme ultraviolet
  (EUV) and white light show that the above burst was associated with a
  flux-rope structure and a coronal mass ejection (CME), respectively. The
  combined height-time plot generated using EUV, radio, and white-light
  data suggests that the different observed features (i.e., the flux rope,
  type II burst, and the CME) are all closely associated. We constructed
  an empirical model for the coronal electron density distribution
  (N <SUB> e </SUB>(r), where r is the heliocentric distance) from
  the above set of observations themselves and used it to estimate the
  coronal magnetic field strength (B) over the range of r values in which
  the respective events were observed. The B values are consistent with
  each other. They vary as B(r) = 2.61 × r <SUP>-2.21</SUP> G in the
  range r ≈ 1.1-2.2R <SUB>⊙</SUB>. As far as we know, similar direct
  estimates of B in the near-Sun corona without assuming a model for N
  <SUB> e </SUB>(r), and by combining cotemporal set of observations in
  two different regions (radio and white-light) of the electromagnetic
  spectrum, have rarely been reported. Further, the present work is a
  novel attempt where the characteristics of a propagating EUV flux-rope
  structure, considered to be the signature of a CME close to the Sun,
  have been used to estimate B(r) in the corresponding distance range.

---------------------------------------------------------
Title: On the Coronal Mass Ejection Detection Rate during Solar
    Cycles 23 and 24
Authors: Michalek, Grzegorz; Gopalswamy, Nat; Yashiro, Seiji
2019ApJ...880...51M    Altcode:
  The Solar and Heliospheric Observatory (SOHO) mission’s white light
  coronagraphs have observed more than 25,000 coronal mass ejections
  (CMEs) from 1996 January to the end of 2015 July. This period of time
  covers almost two solar cycles (23 and 24). The basic attributes of
  CMEs, reported in the SOHO/Large Angle and Spectrometric Coronagraph
  (LASCO) catalog, during these solar cycles were statistically
  analyzed. The question of the CME detection rate and its connection
  to the solar cycles was considered in detail. Based on the properties
  and detection rate, CMEs can be divided into two categories: regular
  and specific events. The regular events are pronounced and follow the
  pattern of sunspot number. On the other hand, the special events are
  poorer and more correlated with the general conditions of heliosphere
  and corona. Nevertheless, both groups of CMEs are the result of the
  same physical phenomenon, viz. release of magnetic energy from closed
  field regions. It was demonstrated that the enhanced CME rate, since the
  solar cycle 23 polar-field reversal, is due to a significant decrease
  of total (magnetic and plasma) heliospheric pressure as well as the
  changed magnetic pattern of solar corona. CMEs expel free magnetic
  energy and helicity from the Sun; therefore, they are related to
  complex solar magnetic field structure. It is also worth emphasizing
  that the CMEs listed in the SOHO/LASCO catalog are real ejections
  (not false identification). Their detection rate reflects the global
  evolution of the magnetic field on the Sun, and not only changes in
  the magnetic structures associated with sunspots.

---------------------------------------------------------
Title: Global Energetics of Solar Flares. VII. Aerodynamic Drag in
    Coronal Mass Ejections
Authors: Aschwanden, Markus J.; Gopalswamy, Nat
2019ApJ...877..149A    Altcode: 2019arXiv190605804A
  The free energy that is dissipated in a magnetic reconnection process
  of a solar flare, generally accompanied by a coronal mass ejection
  (CME), has been considered as the ultimate energy source of the global
  energy budget of solar flares in previous statistical studies. Here
  we explore the effects of the aerodynamic drag force on CMEs, which
  supplies additional energy from the slow solar wind to a CME event,
  besides the magnetic energy supply. For this purpose, we fit the
  analytical aerodynamic drag model of Cargill and Vršnak et al. to
  the height-time profiles r(t) of LASCO/SOHO data in 14,316 CME events
  observed during the first 8 yr (2010-2017) of the Solar Dynamics
  Observatory era (ensuring EUV coverage with AIA). Our main findings
  are (1) a mean solar wind speed of w = 472 ± 414 km s<SUP>-1</SUP>,
  (2) a maximum drag-accelerated CME energy of E <SUB>drag</SUB> ≲
  2 × 10<SUP>32</SUP> erg, (3) a maximum flare-accelerated CME energy
  of E <SUB>flare</SUB> ≲ 1.5 × 10<SUP>33</SUP> erg, (4) the ratio
  of the summed kinetic energies of all flare-accelerated CMEs to the
  drag-accelerated CMEs amounts to a factor of 4, (5) the inclusion
  of the drag force slightly lowers the overall energy budget of CME
  kinetic energies in flares from ≈7% to ≈4%, and (6) the arrival
  times of CMEs at Earth can be predicted with an accuracy of ≈23%.

---------------------------------------------------------
Title: Reconstructing Extreme Space Weather From Planet Hosting Stars
Authors: Airapetian, Vladimir; Adibekyan, V.; Ansdell, M.; Alexander,
   D.; Barklay, T.; Bastian, T.; Boro Saikia, S.; Cohen, O.; Cuntz,
   M.; Danchi, W.; Davenport, J.; DeNolfo, G.; DeVore, R.; Dong, C. F.;
   Drake, J. J.; France, K.; Fraschetti, F.; Herbst, K.; Garcia-Sage,
   K.; Gillon, M.; Glocer, A.; Grenfell, J. L.; Gronoff, G.; Gopalswamy,
   N.; Guedel, M.; Hartnett, H.; Harutyunyan, H.; Hinkel, N. R.; Jensen,
   A. G.; Jin, M.; Johnstone, C.; Kahler, S.; Kalas, P.; Kane, S. R.;
   Kay, C.; Kitiashvili, I. N.; Kochukhov, O.; Kondrashov, D.; Lazio, J.;
   Leake, J.; Li, G.; Linsky, J.; Lueftinger, T.; Lynch, B.; Lyra, W.;
   Mandell, A. M.; Mandt, K. E.; Maehara, H.; Miesch, M. S.; Mickaelian,
   A. M.; Mouschou, S.; Notsu, Y.; Ofman, L.; Oman, L. D.; Osten, R. A.;
   Oran, R.; Petre, R.; Ramirez, R. M.; Rau, G.; Redfield, S.; Réville,
   V.; Rugheimer, S.; Scheucher, M.; Schlieder, J. E.; Shibata, K.;
   Schnittman, J. D.; Soderblom, David; Strugarek, A.; Turner, J. D.;
   Usmanov, A.; Van Der Holst, B.; Vidotto, A.; Vourlidas, A.; Way, M. J.;
   Wolk, Scott J.; Zank, G. P.; Zarka, P.; Kopparapu, R.; Babakhanova,
   S.; Pevtsov, A. A.; Lee, Y.; Henning, W.; Colón, K. D.; Wolf, E. T.
2019BAAS...51c.564A    Altcode: 2019astro2020T.564A; 2019arXiv190306853A
  The goal of this white paper is to identify and describe promising key
  research goals to aid the theoretical characterization and observational
  detection of ionizing radiation from quiescent and flaring upper
  atmospheres of planet hosts as well as properties of stellar coronal
  mass ejections (CMEs) and stellar energetic particle (SEP) events.

---------------------------------------------------------
Title: Obituary: Mukul R. Kundu (1930-2010)
Authors: Gopalswamy, Nat
2019BAAS...51b0314G    Altcode:
  Renowned solar physicist and radio astronomer Mukul Ranjan Kundu
  died on 17 June 2010 near College Park, Maryland, from complications
  after an automobile accident that occurred when he was returning home
  from work. A recipient of the American Astronomical Society's 2007
  George Ellery Hale Prize, Mukul spent his entire career studying
  the radiophysics of the Sun. His work significantly advanced the
  understanding of the interactions between accelerated electrons and the
  magnetized solar corona and of the myriad nonthermal radio phenomena
  that resulted.

---------------------------------------------------------
Title: Explicit IMF B<SUB>y</SUB>-Effect Maximizes at Subauroral
    Latitudes (Dedicated to the Memory of Eigil Friis-Christensen)
Authors: Holappa, L.; Gopalswamy, N.; Mursula, K.
2019JGRA..124.2854H    Altcode: 2019arXiv190404568H
  The most important parameter in the coupling between solar wind
  and geomagnetic activity is the B<SUB>z</SUB>-component of the
  interplanetary magnetic field (IMF). However, recent studies have
  shown that IMF B<SUB>y</SUB> is an additional, independent driver of
  geomagnetic activity. We use here local geomagnetic indices from a large
  network of magnetic stations to study how IMF B<SUB>y</SUB> affects
  geomagnetic activity at different latitudes for all solar wind and,
  separately, during coronal mass ejections. We show that geomagnetic
  activity, for all solar wind, is 20% stronger for B<SUB>y</SUB> &gt;
  0 than for B<SUB>y</SUB> &lt; 0 at subauroral latitudes of about
  60° corrected geomagnetic latitude. During coronal mass ejections,
  the B<SUB>y</SUB>-effect is larger, about 40%, at slightly lower
  latitudes of about 57° (corrected geomagnetic) latitude. These results
  highlight the importance of the IMF B<SUB>y</SUB>-component for space
  weather at different latitudes and must be taken into account in space
  weather modeling.

---------------------------------------------------------
Title: Simulating Solar Coronal Mass Ejections Constrained by
    Observations of Their Speed and Poloidal Flux
Authors: Singh, T.; Yalim, M. S.; Pogorelov, N. V.; Gopalswamy, N.
2019ApJ...875L..17S    Altcode: 2019arXiv190400140S
  We demonstrate how the parameters of a Gibson-Low flux-rope-based
  coronal mass ejection (CME) can be constrained using remote
  observations. Our Multi-Scale Fluid-Kinetic Simulation Suite has
  been used to simulate the propagation of a CME in a data-driven solar
  corona background computed using the photospheric magnetogram data. We
  constrain the CME model parameters using the observations of such
  key CME properties as its speed, orientation, and poloidal flux. The
  speed and orientation are estimated using multi-viewpoint white-light
  coronagraph images. The reconnected magnetic flux in the area covered
  by the post-eruption arcade is used to estimate the poloidal flux in
  the CME flux rope. We simulate the partial halo CME on 2011 March 7
  to demonstrate the efficiency of our approach. This CME erupted with
  the speed of 812 km s<SUP>-1</SUP> and its poloidal flux, as estimated
  from source active region data, was 4.9 × 10<SUP>21</SUP> Mx. Using
  our approach, we were able to simulate this CME with the speed 840
  km s<SUP>-1</SUP> and the poloidal flux of 5.1 × 10<SUP>21</SUP> Mx,
  in remarkable agreement with the observations.

---------------------------------------------------------
Title: On the Properties of Solar Energetic Particle Events Associated
    with Metric Type II Radio Bursts
Authors: Mäkelä, P.; Gopalswamy, N.; Xie, H.; Akiyama, S.; Yashiro,
   S.; Thakur, N.
2019SunGe..14..123M    Altcode: 2019SunGe..14...123
  Metric type II solar radio bursts and solar energetic particles (SEPs)
  are both associated with shock fronts driven by coronal mass ejections
  (CMEs) in the solar corona. Recent studies of ground level enhancements
  (GLEs), regular large solar energetic particle (SEP) events and filament
  eruption (FE) associated large SEP events have shown that SEP events are
  organized by spectral index of proton fluence spectra and by the average
  starting frequencies of the associated type II radio bursts. Both these
  results indicate a hierarchical relationship between CME kinematics
  and SEP event properties. In this study, we expand the investigations
  to fluence spectra and the longitudinal extent of metric type II
  associated SEP events including low-intensity SEP events. We utilize
  SEP measurements of particle instruments on the Solar and Heliospheric
  Observatory (SOHO) and Solar Terrestrial Relations Observatory (STEREO)
  spacecraft together with radio bursts observations by ground-based
  radio observatories during solar cycle 24. Our results show that
  low-intensity SEP events follow the hierarchy of spectral index or
  the hierarchy of the starting frequency of type II radio bursts. We
  also find indications of a trend between the onset frequency of metric
  type II bursts and the estimated longitudinal extent of the SEP events
  although the scatter of data points is quite large. These two results
  strongly support the idea of SEP acceleration by shocks. Stronger
  shocks develop closer to the Sun.

---------------------------------------------------------
Title: A Catalog of Type II radio bursts observed by Wind/WAVES and
    their Statistical Properties
Authors: Gopalswamy, N.; Mäkelä, P.; Yashiro, S.
2019SunGe..14..111G    Altcode: 2019arXiv191207370G; 2019SunGe..14...111
  Solar type II radio bursts are the signature of particle acceleration by
  shock waves in the solar corona and interplanetary medium. The shocks
  originate in solar eruptions involving coronal mass ejections (CMEs)
  moving at super-Alfvenic speeds. Type II bursts occur at frequencies
  ranging from hundreds of MHz to tens of kHz, which correspond to
  plasma frequencies prevailing in the inner heliosphere from the
  base of the solar corona to the vicinity of Earth. Type II radio
  bursts occurring at frequencies below the ionospheric cutoff are
  of particular importance, because they are due to very energetic
  CMEs that can disturb a large volume of the heliosphere. The
  underlying shocks accelerate not only electrons that produce the
  type II bursts, but also protons and heavy ions that have serious
  implications for space weather. The type II radio burst catalog
  (https://cdaw.gsfc.nasa.gov/CME_list/radio/waves_type2.html) presented
  here provides detailed information on the bursts observed by the Radio
  and Plasma Wave Experiment (WAVES) on board the Wind Spacecraft. The
  catalog is enhanced by compiling the associated flares, CMEs, and solar
  energetic particle (SEP) events including their basic properties. We
  also present the statistical properties of the radio bursts and the
  associated phenomena, including solar-cycle variation of the occurrence
  rate of the type II bursts.

---------------------------------------------------------
Title: Evidence for Shock Source of Solar Sustained Gamma-ray
Emission: Fermi, Wind, and SOHO Observations
Authors: Gopalswamy, N.; Mäkelä, Pertti; Yashiro, Seiji; Lara
   Sanchez, Alejandro; Xie, Hong; Akiyama, Sachiko; MacDowall, Robert J.
2019AAS...23340106G    Altcode:
  Fermi Large Area Telescope (Fermi/LAT) observations have shown that
  sustained gamma-ray emission (SGRE) from the Sun is rather common. Such
  events are now called sustained gamma ray emission (SGRE) events. Some
  SGRE events last for almost a day. SGRE is thought to be pion continuum
  resulting from the impact of &gt;300 MeV protons impacting the solar
  chromosphere. Two sources of the high-energy protons have been discussed
  in the literature: (i) continued acceleration/trapping of protons in
  large-scale magnetic structures in the associated solar eruption and
  (ii) precipitation of sunward propagating protons accelerated in
  CME-driven shocks. One of the best observational signatures of CME
  shocks is the interplanetary type II radio emission due to nonthermal
  electrons accelerated in the shock front. Shocks start accelerating
  particles very close to the Sun and often continue to do so far into
  the IP medium resulting in kilohertz radio emission. We examined the
  type II burst properties such as the duration and ending frequencies
  and compared them with the SGRE durations. The SGRE duration has a
  significant linear relationship with the duration and ending frequency
  of type II bursts. This result strongly supports the idea that protons
  accelerated at the shock front travel back to the Sun to precipitate and
  produce SGRE. The protons must be traveling along field lines threading
  the shock front and lying at the periphery of the CME flux rope. Initial
  estimates show that the shocks at a distance of several tens of solar
  radii when the SGRE and type II bursts end. The required &gt;300 MeV
  proton events are not observed at Earth in most of the events. This can
  be explained by the fact that SEP events need magnetic connectivity
  to the observer, whereas type II bursts and SGRE are electromagnetic
  emissions and hence do not have the connectivity requirement.

---------------------------------------------------------
Title: Interplanetary Type II Radio Bursts from Wind/WAVES and
Sustained Gamma-Ray Emission from Fermi/LAT: Evidence for Shock Source
Authors: Gopalswamy, Nat; Mäkelä, Pertti; Yashiro, Seiji; Lara,
   Alejandro; Xie, Hong; Akiyama, Sachiko; MacDowall, Robert J.
2018ApJ...868L..19G    Altcode:
  We present quantitative evidence that interplanetary type II radio
  bursts and sustained gamma-ray emission (SGRE) events from the Sun
  are closely related. Out of about 30 SGRE events reported in Share
  et al. we consider 13 events that had a duration exceeding ∼5 hr to
  exclude any flare-impulsive phase gamma-rays. The SGRE duration also
  has a linear relation with the ending frequency of the bursts. The
  synchronism between the ending times of SGRE and the type II emission
  strongly supports the idea that the same shock accelerates electrons to
  produce type II bursts and protons (&gt;300 MeV) that propagate from
  the shock to the solar surface to produce SGRE via pion decay. The
  acceleration of high-energy particles is confirmed by the associated
  solar energetic particle (SEP) events detected at Earth and/or at the
  Solar Terrestrial Relations Observatory spacecraft. Furthermore, the
  presence of &gt;300 MeV protons is corroborated by the fact that the
  underlying coronal mass ejections (CMEs) had properties identical to
  those associated with ground-level enhancement events: they had speeds
  of &gt;2000 km s<SUP>-1</SUP> and all were full-halo CMEs. Many SEP
  events did not have detectable flux at Earth in the &gt;300 MeV energy
  channels, presumably because of poor magnetic connectivity.

---------------------------------------------------------
Title: Coronal flux ropes and their interplanetary counterparts
Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Xie, H.
2018JASTP.180...35G    Altcode: 2017arXiv170508912G
  We report on a study comparing coronal flux ropes inferred from
  eruption data with their interplanetary counterparts constructed
  from in situ data. The eruption data include the source-region
  magnetic field, post-eruption arcades, and coronal mass ejections
  (CMEs). Flux ropes were fit to the interplanetary CMEs (ICMEs)
  considered for the 2011 and 2012 Coordinated Data Analysis Workshops
  (CDAWs). We computed the total reconnected flux involved in each of
  the associated solar eruptions and found it to be closely related to
  flare properties, CME kinematics, and ICME properties. By fitting flux
  ropes to the white-light coronagraph data, we obtained the geometric
  properties of the flux ropes and added magnetic properties derived
  from the reconnected flux. We found that the CME magnetic field in the
  corona is significantly higher than the ambient magnetic field at a
  given heliocentric distance. The radial dependence of the flux-rope
  magnetic field strength is faster than that of the ambient magnetic
  field. The magnetic field strength of the coronal flux ropes is also
  correlated with that in interplanetary flux ropes constructed from
  in situ data, and with the observed peak magnetic field strength in
  ICMEs. The physical reason for the observed correlation between the
  peak field strength in ICMEs is the higher magnetic field content in
  faster coronal flux ropes and ultimately the higher reconnected flux
  in the eruption region. The magnetic flux ropes constructed from the
  eruption data and coronagraph observations provide a realistic input
  that can be used by various models to predict the magnetic properties
  of ICMEs at Earth and other destination in the heliosphere.

---------------------------------------------------------
Title: Very narrow coronal mass ejections producing solar energetic
    particles
Authors: Bronarska, K.; Wheatland, M. S.; Gopalswamy, N.; Michalek, G.
2018A&A...619A..34B    Altcode:
  <BR /> Aims: Our main aim is to study the relationship between
  low-energy solar particles (energies below 1 MeV) and very narrow
  coronal mass ejections ("jets" with angular width ≤ 20°). <BR />
  Methods: For this purpose, we considered 125 very narrow coronal mass
  ejections (CMEs) from 1999 to 2003 that are potentially associated
  with low-energy solar particles (LESPs). These events were chosen on
  the basis of their source location. We studied only very narrow CMEs at
  the western limb, which are expected to have good magnetic connectivity
  with Earth. <BR /> Results: We found 24 very narrow CMEs associated
  with energetic particles such as ions (protons and <SUP>3</SUP>He),
  electrons, or both. We show that arrival times at Earth of energetic
  particles are consistent with onset times of the respective CMEs, and
  that in the same time intervals, there are no other potential sources
  of energetic particles. We also demonstrate statistical differences
  for the angular width distributions using the Kolmogorov-Smirnov
  test for angular widths for these 24 events. We consider a coherent
  sample of jets (mostly originating from boundaries of coronal holes)
  to identify properties of events that produce solar energetic particles
  (velocities, widths, and position angles). Our study presents a new
  approach and result: very narrow CMEs can generate low-energy particles
  in the vicinity of Earth without other activity on the Sun. The results
  could be very useful for space weather forecasting.

---------------------------------------------------------
Title: Sun-to-earth propagation of the 2015 June 21 coronal mass
    ejection revealed by optical, EUV, and radio observations
Authors: Gopalswamy, N.; Mäkelä, P.; Akiyama, S.; Yashiro, S.; Xie,
   H.; Thakur, N.
2018JASTP.179..225G    Altcode: 2018arXiv180710979G
  We investigate the propagation of the 2015 June 21 CME-driven shock
  as revealed by the type II bursts at metric and longer wavelengths
  and coronagraph observations. The CME was associated with the second
  largest geomagnetic storm of solar cycle 24 and a large solar energetic
  particle (SEP) event. The eruption consisted of two M-class flares,
  with the first one being confined, with no metric or interplanetary
  radio bursts. However, there was intense microwave burst, indicating
  accelerated particles injected toward the Sun. The second flare was
  eruptive that resulted in a halo CME. The CME was deflected primarily
  by an equatorial coronal hole that resulted in the modification of
  the intensity profile of the associated SEP event and the duration of
  the CME at Earth. The interplanetary type II burst was particularly
  intense and was visible from the corona all the way to the vicinity of
  the Wind spacecraft with fundamental-harmonic structure. We computed
  the shock speed using the type II drift rates at various heliocentric
  distances and obtained information on the evolution of the shock that
  matched coronagraph observations near the Sun and in-situ observations
  near Earth. The depth of the geomagnetic storm is consistent with the
  1-AU speed of the CME and the magnitude of the southward component.

---------------------------------------------------------
Title: Direction-finding Analysis of the 2012 July 6 Type II Solar
    Radio Burst at Low Frequencies
Authors: Mäkelä, Pertti; Gopalswamy, Nat; Akiyama, Sachiko
2018ApJ...867...40M    Altcode:
  The 2012 July 6 X1.1 flare at S13W59 and a halo coronal mass ejection
  (CME) with a space speed of ∼1900 km s<SUP>-1</SUP> were associated
  with type III and type II radio bursts. The metric-to-decametric type
  II radio burst extended down to ∼5 MHz. Simultaneously, a slowly
  drifting feature with a harmonic structure was observed by Wind and
  Solar Terrestrial Relations Observatory radio receivers around and below
  1 MHz, above the strong type III radio burst at lower frequencies. The
  radio direction-finding analysis of this lower-frequency interplanetary
  (IP) type II radio burst indicates that the radio source was located
  near the nose and possibly toward the southern flank of the CME-driven
  shock. These results provide an independent confirmation of the previous
  suggestions that when the metric and IP type II bursts are overlapping,
  the lower-frequency IP type II radio burst originates near the shock
  nose, whereas the source of the higher-frequency metric type II burst
  is closer to the Sun in the shock flank region. These results further
  support the idea that the coronal and IP type II bursts are produced
  by the same CME-driven shock.

---------------------------------------------------------
Title: Fermi, Wind, and SOHO Observations of Sustained Gamma-Ray
    Emission from the Sun
Authors: Gopalswamy, N.; Makela, P.; Yashiro, S.; Lara, A.; Xie, H.;
   Akiyama, S.; MacDowall, R. J.
2018arXiv181008958G    Altcode:
  We report on the linear relationship between the durations of two types
  of electromagnetic emissions associated with shocks driven by coronal
  mass ejections: sustained gamma-ray emission (SGRE) and interplanetary
  type II radio bursts. The relationship implies that shocks accelerate
  about 10 keV electrons (for type II bursts) and greater than 300 MeV
  protons (for SGRE) roughly over the same duration. The SGRE events are
  from the Large Area Telescope (LAT) on board the Fermi satellite, while
  the type II bursts are from the Radio and Plasma Wave Experiment (WAVES)
  on board the Wind spacecraft. Here we consider five SGRE events that
  were not included in a previous study of events with longer duration
  (greater than 5 hours). The five events are selected by relaxing the
  minimum duration to 3 hours. We found that some SGRE events had a tail
  that seems to last until the end of the associated type II burst. We
  pay special attention to the 2011 June 2 SGRE event that did not
  have a large solar energetic particle event at Earth or at the STEREO
  spacecraft that was well connected to the eruption. We suggest that
  the preceding CME acted as a magnetic barrier that mirrored protons
  back to Sun.

---------------------------------------------------------
Title: Properties of DH Type II Radio Bursts and Their Space Weather
    Implications
Authors: Gopalswamy, N.; Mäkelä, P.
2018arXiv181011173G    Altcode:
  We report on the properties of type II radio bursts observed by the
  Radio and Plasma Wave Experiment (WAVES) on board the Wind spacecraft
  over the past two solar cycles. We confirm that the associated coronal
  mass ejections (CMEs) are fast and wide, more than half the CMEs
  being halos. About half of the type II bursts extend down to 0.5 MHz,
  corresponding to a heliocentric distance of tens of solar radii. The
  DH type II bursts are mostly confined to the active region belt and
  their occurrence rate follows the solar activity cycle. Type II burst
  occurring on the western hemisphere of the Sun and extending to lower
  frequencies are good indicators of a solar energetic particle event.

---------------------------------------------------------
Title: The Effects of Uncertainty in Initial CME Input Parameters
    on Deflection, Rotation, B<SUB>z</SUB>, and Arrival Time Predictions
Authors: Kay, C.; Gopalswamy, N.
2018JGRA..123.7220K    Altcode:
  Understanding the effects of coronal mass ejections (CMEs)
  requires knowing if and when they will impact and their properties
  upon impact. Of particular importance is the strength of a CME's
  southward magnetic field component (B<SUB>z</SUB>). Kay et al. (2013, <A
  href="https://doi:10.1088/0004-637X/775/1/5">https://doi:10.1088/0004-637X/775/1/5</A>,
  2015, <A href="https://doi:10.1088/948
  0004-637X/805/2/168">https://doi:10.1088/948 0004-637X/805/2/168</A>)
  have shown that the simplified analytic model Forecasting a
  CME's Altered Trajectory (ForeCAT) can reproduce the deflection
  and rotation of CMEs. Kay, Gopalswamy, Reinard, and Opher (2017, <A
  href="https://doi.org/10.3847/1538-4357/835/2/117">https://doi.org/10.3847/1538-4357/835/2/117</A>)
  introduced ForeCAT In situ Data Observer, which uses ForeCAT results
  to simulate magnetic field profiles. ForeCAT In situ Data Observer
  reproduces the in situ observations on roughly hourly time scales,
  suggesting that these models could be extremely useful for predictions
  of B<SUB>z</SUB>. However, as with all models, both models are
  sensitive to their input parameters, which may not be precisely known
  for predictions. We explore this sensitivity using ensembles having
  small changes in the initial latitude, longitude, and orientation
  of the erupting CME. We explore the effects of different background
  magnetic field models and find that the changes in deflection and
  rotation resulting from the uncertainty in the initial parameters
  tend to exceed the changes from different magnetic backgrounds. The
  range in the in situ profiles tends to scale with the range in the
  deflection and rotation. We also consider a simple arrival time model
  using ForeCAT results and find an average absolute error of only 3
  hr. We show that an uncertainty in the CME position of 8.1° ± 6.9°
  leads to variations of 6 hr in the arrival time. This measure depends
  strongly on the location of impact within the CME with the arrival
  time changing less for impacts near the nose.

---------------------------------------------------------
Title: Long-term solar activity studies using microwave imaging
    observations and prediction for cycle 25
Authors: Gopalswamy, N.; Mäkelä, P.; Yashiro, S.; Akiyama, S.
2018JASTP.176...26G    Altcode: 2018arXiv180402544G
  We use microwave imaging observations from the Nobeyama Radioheliograph
  at 17 GHz for long-term studies of solar activity. In particular,
  we use the polar and low-latitude brightness temperatures as proxies
  to the polar and active-region magnetic fields, respectively. We also
  use the locations of prominence eruptions as a proxy to the filament
  locations to study their time variation. We show that the polar
  microwave brightness temperature is highly correlated with the polar
  magnetic field strength and the fast solar wind speed. We also show that
  the polar microwave brightness in one solar cycle is correlated with
  the low latitude brightness with a lag of about half a solar cycle. We
  use this correlation to predict the strength of the solar cycle 25:
  the smoothed sunspot numbers in the southern and northern hemispheres
  can be predicted as 89 and 59, respectively. These values indicate that
  cycle 25 will not be too different from cycle 24 in its strength. We
  also combined the rush-to-the-pole data from Nobeyama prominences with
  historical data going back to 1860 to study the north-south asymmetry
  of sign reversal at solar poles. We find that the reversal asymmetry
  has a quasi-periodicity of 3-5 cycles.

---------------------------------------------------------
Title: A small satellite mission for solar coronagraphy
Authors: Gopalswamy, N.; Gong, Qian
2018SPIE10769E..0XG    Altcode:
  We present on a concept study of the Goddard Miniature Coronagraph
  (GMC) mission for measuring the plasma flow in the solar corona in
  the form of solar wind and coronal mass ejections (CMEs). These mass
  flows can dramatically alter the near-Earth space environment to
  hazardous conditions posing danger to human technology in space. The
  primary science objective of the mission is to measure the properties
  of CMEs, coronal structures, and the solar wind near the Sun. The
  miniaturization of the coronagraph involves using a single-stage
  optics and a polarization camera, both of which reduce the size of the
  coronagraph. GMC will be accommodated in a small satellite that can
  be built with cubesat material to minimize cost. The development of
  the Dellingr mission at NASA/GSFC has provided expertise and a clear
  pathway to build the GMC mission. The hardware and software used for
  the Dellingr mission are technically sound, so the GMC mission can be
  fully defined. Software, pointing, control and communications systems
  developed for GSFC CubeSats can be readily adapted to cut costs. We
  present orbit options such as an ISS orbit or a Sun synchronous dawndusk
  polar orbit with the aim of maximizing solar observations.

---------------------------------------------------------
Title: Dependence of Coronal Mass Ejection Properties on Their
    Solar Source Active Region Characteristics and Associated Flare
    Reconnection Flux
Authors: Pal, Sanchita; Nandy, Dibyendu; Srivastava, Nandita;
   Gopalswamy, Nat; Panda, Suman
2018ApJ...865....4P    Altcode: 2018arXiv180804144P
  The near-Sun kinematics of coronal mass ejections (CMEs) determine
  the severity and arrival time of associated geomagnetic storms. We
  investigate the relationship between the deprojected speed and
  kinetic energy of CMEs and magnetic measures of their solar sources,
  reconnection flux of associated eruptive events, and intrinsic
  flux-rope characteristics. Our data covers the period 2010-2014 in
  solar cycle 24. Using vector magnetograms of source active regions,
  we estimate the size and nonpotentiality. We compute the total
  magnetic reconnection flux at the source regions of CMEs using
  the post-eruption arcade method. By forward modeling the CMEs,
  we find their deprojected geometric parameters and constrain their
  kinematics and magnetic properties. Based on an analysis of this
  database, we report that the correlation between CME speed and their
  source active region size and global nonpotentiality is weak, but not
  negligible. We find the near-Sun velocity and kinetic energy of CMEs to
  be well correlated with the associated magnetic reconnection flux. We
  establish a statistically significant empirical relationship between
  the CME speed and reconnection flux that may be utilized for prediction
  purposes. Furthermore, we find CME kinematics to be related with the
  axial magnetic field intensity and relative magnetic helicity of their
  intrinsic flux ropes. The amount of coronal magnetic helicity shed by
  CMEs is found to be well correlated with their near-Sun speeds. The
  kinetic energy of CMEs is well correlated with their intrinsic magnetic
  energy density. Our results constrain processes related to the origin
  and propagation of CMEs and may lead to better empirical forecasting
  of their arrival and geoeffectiveness.

---------------------------------------------------------
Title: Extreme Kinematics of the 2017 September 10 Solar Eruption
    and the Spectral Characteristics of the Associated Energetic Particles
Authors: Gopalswamy, N.; Yashiro, S.; Mäkelä, P.; Xie, H.; Akiyama,
   S.; Monstein, C.
2018ApJ...863L..39G    Altcode: 2018arXiv180709906G
  We report on the 2017 September 10 ground-level enhancement (GLE)
  event associated with a coronal mass ejection whose initial acceleration
  (∼9.1 km s<SUP>-2</SUP>) and initial speed (∼4300 km s<SUP>-1</SUP>)
  were among the highest observed in the Solar and Heliospheric
  Observatory era. The GLE event was of low intensity (∼4.4% above
  background) and softer-than-average fluence spectrum. We suggest that
  poor connectivity (longitudinal and latitudinal) of the source to Earth
  compounded by the weaker ambient magnetic field contributed to these GLE
  properties. Events with similar high initial speed either lacked GLE
  association or had softer fluence spectra. The shock-formation height
  inferred from the metric type II burst was ∼1.4 Rs, consistent with
  other GLE events. The shock height at solar particle release (SPR)
  was ∼4.4 ± 0.38 Rs, consistent with the parabolic relationship
  between the shock height at SPR and source longitude. At SPR, the
  eastern flank of the shock was observed in EUV projected on the disk
  near the longitudes magnetically connected to Earth: W60 to W45.

---------------------------------------------------------
Title: A New Technique to Provide Realistic Input to CME Forecasting
    Models
Authors: Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Xie, Hong
2018IAUS..335..258G    Altcode: 2017arXiv170903160G
  We report on a technique to construct a flux rope (FR) from eruption
  data at the Sun. The technique involves line-of-sight magnetic fields,
  post-eruption arcades in the corona, and white-light coronal mass
  ejections (CMEs) so that the FR geometric and magnetic properties can
  be fully defined in addition to the kinematic properties. We refer to
  this FR as FRED (Flux Rope from Eruption Data). We illustrate the FRED
  construction using the 2012 July 12 eruption and compare the coronal
  and interplanetary properties of the FR. The results indicate that the
  FRED input should help make realistic predictions of the components
  of the FR magnetic field in the heliosphere.

---------------------------------------------------------
Title: Globally Coordinated Space Weather Education and Outreach
    Initiative
Authors: Chulaki, Anna; Glover, Alexi; Nandi, Dibyendu; Gopalswamy,
   Nat; Di Pippo, Simonetta
2018cosp...42E.656C    Altcode:
  The poster will summarize outcome from thePSW.5-Panel 2: Capacity
  building in space weather: Globally coordinated space weather
  education and outreach initiativesWe will provide summaries of ongoing
  international educational activities in space weather and discuss
  needs and opportunities for global coordination in space weather
  awareness, education and outreach. <P />What aspects of space weather
  education/outreach require special attention? <P />What type of novel
  education initiatives should we undertake? <P />Do we need a framework
  for coordinating international space weather educational initiatives? <P
  />What should be the role of COSPAR PSW in space weather education?

---------------------------------------------------------
Title: Relationship between SEP peak intensity and shock speed,
    CME width and acceleration; no
Authors: Xie, Hong; St. Cyr, O. C.; Makela, P.; Gopalswamy, N.
2018shin.confE.112X    Altcode:
  We study the large solar energetic particle (SEP) events that were
  detected by GOES in the &gt;10 MeV energy channel during December 2006
  to January 2016. Data used in this study includes the Solar Electron
  Proton Telescope (SEPT) and High Energy Telescopes (HET) on STEREO
  A and B, the Electron, Proton, and Alpha Monitor (EPAM) on ACE,
  and the Energetic and Relativistic Nuclei and Electron instrument
  (ERNE) on SOHO. From multi-spacecraft observations we obtained the
  peak intensity I0 at the center of the Gausssian function using the
  Gausssian fit. We then study the relationship between electron and
  proton peak intensity and shock speed and CME width. We found that
  the correlation between electron and proton peak intensity and shock
  speed can be improved by taking into account the effects of CME width
  and SEP connection angle. We also found that SEP onset and peak delays
  relative to type III onset are closely related to the CME accelerations
  at the main and residual acceleration phases. The implication for the
  SEP forecast of our obtained results will be discussed.

---------------------------------------------------------
Title: The Effects of Uncertainty on Deflection, Rotation, Bz and
    Arrival Time Predictions
Authors: Kay, Christina; Gopalswamy, Nat
2018shin.confE.195K    Altcode:
  Understanding the effects of coronal mass ejections (CMEs) requires
  knowing not only if and when they will impact, but also their
  properties upon impact. Of particular importance is the strength of
  a CME's southward magnetic field component (Bz). Kay et al. (2013,
  2015) have shown that the simplified analytic model ForeCAT can
  be used to reproduce the deflection and rotation of CMEs. Kay et
  al. (2017) introduced FIDO, which uses the position and orientation
  from ForeCAT to simulate magnetic field profiles. FIDO reproduces the
  in situ observations on roughly hourly time scales, suggesting that
  the combination of ForeCAT and FIDO could be extremely useful for
  predictions of Bz. However, as with all models, both ForeCAT and FIDO
  are sensitive to their input parameters, which may not be precisely
  known for actual predictions. We explore the sensitivity of both
  models using ensembles with small changes in the initial latitude,
  longitude, and orientation of the erupting CME. Additionally, thus
  far ForeCAT has only been run using a Potential Field Source Surface
  (PFSS) magnetic background driven by a synoptic map. We explore the
  effects of different magnetic backgrounds - the Schatten Current Sheet
  model and synchronic maps. We find that the changes in deflection and
  rotation resulting from the uncertainty in the initial parameters tend
  to exceed the changes from different magnetic backgrounds. The range
  in the in situ profiles tends to scale with the range in the deflection
  and rotation. We also consider the effects of these changes in a simple
  arrival time model and show that accurate arrival times can only be
  achieved if the CME position and orientation are precisely known.

---------------------------------------------------------
Title: Unusual Polar Conditions of the Sun during Solar Cycle 24
    and its Iplications for Cycle 25
Authors: Gopalswamy, Nat; Masuda, Satoshi; Yashiro, Seiji; Akiyama,
   Sachiko; Shibasaki, Kiyoto
2018cosp...42E1250G    Altcode:
  Polar field strength in one solar cycle is known to indicate the
  strength (e.g., Sunspot number) and phase of the next cycle. In
  particular the polar field strength (or its proxies such as the
  polar coronal hole area and microwave polar brightness) during the
  minimum phase of a given cycle seem to be well correlated with the
  maximum sunspot number of the next cycle. Polar prominence eruptions
  and coronal mass ejections have also been found to be indicators
  of low polar field; their cessation signals the time of polarity
  reversal. While these indicators are present in the current cycle,
  significant differences are found regarding the phase lag between the
  two hemispheres and the duration of polar eruptions. We use data from
  the Nobeyama Radioheliograph, the Solar Dynamics Observatory, SOLIS,
  and Wilcox Solar Observatory to highlight these differences. We find
  that the north polar region of the Sun has near-zero field strength for
  more than three years. This is unusually long and caused by surges of
  both polarities heading toward the north pole that prevent the buildup
  of the polar field. This seems to be due to anti-Hale active regions
  that appeared around the 2012 peak sunspot activity in the northern
  hemisphere. The unusual condition is consistent with (i) the continued
  high-latitude prominence eruption, (ii) the extended period of high
  tilt angle of the heliospheric current sheet, (iii) the weak microwave
  polar brightness, and (iv) the lack of north polar coronal hole. On
  the other hand, the south polar field has started building up and the
  coronal hole has appeared in early 2015 because of large active regions
  of the correct tilt in the southern hemisphere during the 2014 peak of
  sunspot activity. The extended period of near-zero field in the north
  polar region should result in very weak and delayed sunspot activity
  in the northern hemisphere in cycle 25. On the other hand the south
  polar field has already increased significantly, suggesting that the
  activity in the southern hemisphere should start early; the amplitude
  will depend on how the south polar fields will evolve in the declining
  phase of cycle 24.

---------------------------------------------------------
Title: Towards a global space weather community hub and a network of
    International Space Weather Action Teams (ISWAT) aiming to advance
    space weather capabilities and to facilitate Global Space Weather
    Roadmap updates
Authors: Kuznetsova, Maria; Glover, Alexi; Gopalswamy, Nat; Di Pippo,
   Simonetta
2018cosp...42E1899K    Altcode:
  Panel 3: COSPAR space weather action teams: A bottom-up component
  of global coordination in space weather.14:00-17:30, Thursday,
  19 July, Room: SR 29 (HH) - Santa Clara Chairs: Masha Kuznetsova
  (NASA, USA), Hermann Opgenoorth (Swedish Institute of Space Physics,
  Sweden)One of the key challenges identified in the COSPAR-ILWS space
  weather roadmap [Schrijver et al., 2015] is a transformation into an
  effectively functioning, information-sharing, global space weather
  community. To address this challenge and to demonstrate the critical
  value of a global coordination the COSPAR Panel on Space Weather will
  coordinate an active network of topical scientific action teams (a.k.a.,
  International Space Weather Action Teams). Action teams will address
  space weather roadmap recommendations, provide a bottom-up push for
  coordination and innovation, serve as a channel for a global community
  voice, assess progress in various areas of space weather, and propose
  regular updates for guiding documents. Moderators of ISWAT clusters
  (action teams grouped by space environment domains and/or impacts)
  and organizers of PSW.1-4 events will present their outlook on the
  ISWAT concept, plans for topical action teams activities for the
  next two years, approaches to Roadmap updates, and invite community
  input and active participation.14:00 - 14:10 Introduction of the
  ISWAT concept. 14:10 - 14:40 Updates from PSW.1-4 (5-7 min)14:40 -
  15:30: ISWAT moderators presentations, Q&amp;A (5-7 min)16:00 - 17:30:
  Panel discussion, Q&amp;A, community feedback Panelists: Jon Linker
  (Predictive Science Inc., USA)Manuela Temmer (University of Gratz,
  Austria)Mario Bisi (RAL SFTC, UK)Robert Wimmer-Schweingruber (University
  of Kiel, Germany)Hermann Opgenoorth (Swedish Institute of Space Physics,
  Sweden)Ian Mann (University of Alberta, Canada)Sean Bruinsma (CNES,
  France)Anna Belehaki (NOA, Greece)Alexi Glover (ESA)Daniel Heynderickx
  (DH Consultancy, Belgium)Norbert Jakowski (DLR, Germany)Manuel Grande
  (Aberystwyth University, UK)

---------------------------------------------------------
Title: Accurate prediction and testing of CME arrival and properties
    from Sun to Earth
Authors: Cairns, Iver; Van der Holst, Bart; Lobzin, Vasili; Schmidt,
   Joachim; Neudegg, Dave; Gopalswamy, Nat; Parkinson, Murray; Steward,
   Graham; Kelly, Andrew
2018cosp...42E.492C    Altcode:
  Most major space weather events are due to fast CMEs and their shocks
  interacting with Earth's magnetosphere. Accurate prediction of CME
  arrival, propagation, and properties is thus vital for prediction of
  space weather at Earth as well as elsewhere in the solar system. In
  particular, it is important to accurately predict the CME velocity,
  shape, and evolution as functions of position and time, as well as the
  flow velocity and magnetic field vector in the coronal and solar wind
  plasma, downstream of the CME shock, and inside the CME. We report the
  results of simulating 4 separate CMEs from the Sun to 1 AU with the
  Space Weather Modelling Framework (SWMF; 2015 and 2016 versions). The
  simulations are set up carefully using Wilcox photospheric magnetogram
  data and coronagraph images and height-time data below 10 solar radii
  from coronagraphs. Outstanding agreement between the observations
  and simulations is found for the CME on 29 November 2013 that was
  directed primarily towards STEREO A. In particular, the CME's arrival
  at STEREO A, deceleration of the CME in agreement with the Gopalswamy
  et al. [2011] model, and the time-varying plasma and field (including
  B_{z}) agree extremely well. from upstream of the CME shock to within
  the CME. Similarly, the results of the simulations to the Earth-directed
  CMEs of 4, 6, and 7 September 2017 range from excellent to very good
  for the arrival time and for the 1-hour averaged density, radial speed,
  B_{z}, and magnetic field strength from the shock to well into the
  CME. These results provide strong evidence that we have the capability
  with the Space Weather Modeling Framework, when sufficiently carefully
  initialized, to accurately predict the properties and evolution of
  CMEs and the interplanetary magnetic field and plasma from the Sun to
  1 AU. This suggests that we are very close to being able to accurately
  predict the triggers for CME-driven space weather at Earth.

---------------------------------------------------------
Title: Metric Type II Onset Frequency and the Longitudinal Extent
    of SEP Events
Authors: Makela, Pertti; Gopalswamy, N.; Yashiro, S.; Thakur, N.;
   Akiyama, S.; Xie, H.
2018shin.confE.116M    Altcode:
  Average starting frequencies of the type II bursts
  observed during ground level enhancements (GLEs), regular and
  filament-eruption-associated solar energetic particle (SEP) events
  have distinct, but overlapping, distributions (Gopalswamy et al. 2017,
  J. Phys. Conf. Ser., Proc. 16th AIAC). Based on these results, we
  studied a possible dependence between the onset frequency of metric
  type II radio bursts and the longitudinal spread of the &gt;25 MeV
  SEP events from the list of Richardson et al. (2014, Sol. Phys. 289)
  covering the first seven years of the STEREO mission. We have used
  radio data available online, mainly from the Radio Solar Telescope
  Network (RSTN) and e-CALLISTO international network of solar radio
  spectrometers, to estimate the type II onset frequencies. We find
  a linear trend between the extent of the SEP events and the onset
  frequency of the metric type II bursts, but the scatter of data points
  is quite large, and correlations are modest.

---------------------------------------------------------
Title: Observational Signatures of CME Structure near the Sun
Authors: Gopalswamy, Nat
2018shin.confE.204G    Altcode:
  Coronagraphic observations tell us about the electron density
  distribution in the CME structure. The famous three-part structure
  is determined by the dense prominence core surrounded by a magnetic
  structure that appears less dense (void) and forms a bright front by
  pushing against the ambient medium. Super-Alfvenic CMEs have another
  overlying structure, the shock sheath that became clear in SOHO/LASCO
  observations, and is now routinely observed in STEREO images. The
  basic magnetic structure underlying CMEs observed in the solar wind
  has been determined to be a flux rope, which is identified with the
  void structure in coronagraphic images. When an eruption happens, what
  is left behind on the Sun is the post-eruption arcade (PEA), which
  is formed over the neutral line from which the prominence erupted as
  part of the CME. The PEA properties provide important clues to the
  understanding of the flux rope structure of CMEs. Coronal dimming is
  another key signature, which helps understand the geometry of the flux
  rope with respect to the PEA and the direction of axial magnetic flux
  rope: PEA and the flux rope are formed due to the same reconnection
  process. Forward modeling CMEs observed in coronagraphic images provides
  the geometrical properties of flux ropes, while the reconnected flux
  in the eruption provides their magnetic properties. The flux rope from
  eruption data (FRED) represents the culmination of the CME research
  over the past half a century.

---------------------------------------------------------
Title: Panel Discussion: Capacity building in space weather: Globally
    coordinated space weather education and outreach initiatives
Authors: Gopalswamy, Nat
2018cosp...42E1249G    Altcode:
  Panel 2: Capacity building in space weather: Globally coordinated space
  weather education and outreach initiatives12:20-13:00, Thursday, 19
  July, Room: SR 29 (HH) -Santa Clara Convener: Dibyendu Nandi (CESSI
  / IISER Kolkata, India)Chair: Nat Gopalswamy (NASA, USA)This panel
  discussion will bring together diverse organizations involved in space
  weather education and outreach activities, provide brief summaries of
  ongoing activities and discuss opportunities for new initiatives of the
  COSPAR Space Weather Panel towards global coordination in space weather
  awareness, education and outreach. 12:20 - 12:40: Opening Statements
  (5 min)12:40 - 13:00: Q&amp;A, Discussion PanelPanelists: Simonetta Di
  Pippo (UNOOSA), Anna Chulaki (CCMC, USA), Alexi Glover (ESA, COSPAR's
  Panel on Capacity Building)Suggested questions to panelists:What aspects
  of space weather education/outreach require special attention? What
  type of novel education initiatives should we undertake?Do we need a
  framework for coordinating international space weather educational
  initiatives?What should be the role of COSPAR PSW in space weather
  education? The scientific committee on solar terrestrial physics
  (SCOSTEP) is an interdisciplinary body of the International Council
  for Science (ICSU) collaborating with five scientific unions unions
  (IAMAS, IAU, IUGG/IAGA, IUPAP, URSI) and three interdisciplinary bodies
  (COSPAR, SCAR, and WDS). SCOSTEP is actively involved in the science,
  capacity building, and public outreach activities related to solar
  terrestrial physics. By design, space weather is a significant part of
  solar terrestrial physics dealing with the short-term variability of
  the Sun and how it affects Earth's space environment. The space weather
  activities of SCOSTEP are conducted via the scientific programs such
  as the current VarSITI (variability of the Sun and Its Terrestrial
  Impact). Of particular interest for space weather is the ISEST
  (International Study of Earth-affecting Solar Transients) project
  directly deals with the two sources of space weather at Earth, viz.,
  coronal mass ejections and high speed solar wind and their consequences
  (geomagnetic storms and solar energetic particle events). As part
  of this project, daily alerts are issued whenever a space-weather
  causing feature such as a filament or a coronal hole appears near the
  disk center of the Sun. SCOSTEP also collaborates with COSPAR, URSI,
  and the International Space Weather Initiative (ISWI) to run Space
  Science Schools for PhD students and young postdocs. These capacity
  building activities enhances space weather literacy among researchers
  in developing countries. SCOSTEP also runs a visiting scholar program
  that provides short-term (1-3 months) training in solar terrestrial
  relationship in advanced laboratories for students from developing
  counties.

---------------------------------------------------------
Title: The COSPAR Capacity Building Workshop at Mekelle University
    in Ethiopia
Authors: Gopalswamy, Nat
2018cosp...42E1251G    Altcode:
  This talk summarizes the experience in organizing the COSPAR
  Capacity-Building Workshop "Coronal and Interplanetary Shocks:
  Analysis of Data from SOHO, Wind, and e-CALLISTO" in Mekelle University,
  Ethiopia. The main objective of the COSPAR Capacity-Building Workshops
  is to encourage the scientific use of space data by scientists in
  developing countries. In particular, in view of the large number
  of extensive archives of data from past and current space missions,
  and the ready access to these and the associated analysis software
  via the internet, the typical workshop aims to provide a highly
  practical training in the use of one or more of these, based on current
  missions. In line with this objective, a two-week workshop introduces
  data analysis of space-based white-light coronagraph observations
  and radio spectral observations from space and ground to study shocks
  driven by coronal mass ejections. In particular, the wealth of data
  accumulated at the CDAW Data Center at NASA Goddard Space Flight
  Center from the ESA/NASA Solar and Heliospheric Observatory (SOHO)
  mission, NASA's Solar Terrestrial Relations Observatory (STEREO),
  NASA's Wind and Advanced Composition Explorer (ACE) missions are
  used. In addition, ground based radio data from the e-CALLISTO network
  and the Radio Solar Telescope Network (RSTN) around the globe are used
  for the study. Context information from NOAA's GOES mission and NASA's
  Solar Dynamics Observatory (SDO) missions are also used. This workshop
  enables scientists and students in developing countries where the e-
  CALLISTO instruments are deployed to use their data in conjunction
  with space data to study Earth- affecting solar transient phenomena.

---------------------------------------------------------
Title: Solar Energetic Particle Events Associated with Prominence
Eruptions: A Case Study
Authors: Thakur, Neeharika; Gopalswamy, N.; Akiyama, S.; Mäkelä,
   P.; Yashiro, S.; Xie, H.; Cohen, C.
2018shin.confE.229T    Altcode:
  We investigated the characteristics the 2015 June 18 large solar
  energetic particle (SEP) event (GOES &gt;10 MeV particle flux was
  &gt;10 particles/(cm^2 s sr)) associated with a prominence eruption
  from the Sun. Recent work (Gopalswamy et al. 2015 ApJ 806, 8) reported
  on a set of large SEP events associated with filament eruption (FE)
  events occurring outside of active regions. The FE-associated SEPs are
  produced by coronal mass ejections (CMEs) that are accelerating and
  forming a shock at large distances from the Sun. Such SEPs exhibit a
  soft energy spectrum with the spectral index &gt;4 in the 10-100 MeV
  range. The 2015 June 18 eruption was associated with an M1.3 flare
  and a prominence eruption from the west limb observed by SDO. The
  associated CME was fast (speed 1714 km/s), and it was accelerating in
  the LASCO field of view (acceleration 27.7 m/s^2). The CME did not
  produce a metric type II radio burst but it was associated with an
  interplanetary (IP) type II radio burst, implying that a strong shock
  formed in the interplanetary medium. We present our initial findings
  of this case study of prominence-associated SEPs.

---------------------------------------------------------
Title: Why was the Fluence Spectrum of the 2017 September 10 GLE
    So Soft?
Authors: Gopalswamy, Nat; Makela, P.; Yashiro, S.; Xie, H.; Akiyama, S.
2018shin.confE.110G    Altcode:
  The 2017 September 10 solar energetic particle (SEP) event with ground
  level enhancement (GLE) from NOAA AR 12673 was the fourth largest event
  in solar cycle 23 in terms of the &gt;10 MeV intensity (1490 pfu). In
  spite of the ultra-high initial speed of 3100 km/s and an initial
  acceleration of 9.4 km s-2, the GLE was rather weak with an intensity
  of only 4.4% above background, much smaller than that of the 2012 May
  17 GLE (18.6%) and only slightly higher than the sub-GLE event of 2014
  January 6 (2.5%). The 10-100 MeV fluence spectrum (fitted to a power
  law) was the third softest among the GLEs of cycles 23 and 24 combined
  (Gopalswamy et al. 2016, ApJ 833, 216). The fluence spectral index was
  3.17±.06, indicating it is softer than the 2012 May 17 GLE (2.48±0.12)
  and the sub-GLE of 2014 January 6 (2.54±0.11). The two GLEs with
  spectra softer than that of the 2017 September 10 event are the ones
  on 1998 August 24 (3.79±0.12) and 2003 November 2 (3.50±0.12). We
  show that poor latitudinal connectivity was the primary reason for
  the soft spectrum in these events: the ecliptic distance was larger
  than the average value (±13?, Gopalswamy et al. ApJ 765, L30) for
  GLE events. If the GeV particles are accelerated near the shock nose,
  a larger ecliptic distance would not be favorable for these particles
  to reach Earth. In the 2017 September 17 event, the flank connected
  to Earth was 20?.3 away from the nose. Since the nose speed of the
  shock was &gt;3000 km/s, the flank speed was still large (&gt;2800
  km/s), so GeV particles were still produced at the flanks. The lower
  energy particles are accelerated over a much larger area of the shock
  resulting in a soft spectrum.

---------------------------------------------------------
Title: Sun-to-Earth simulation of the July 12, 2012 geo-effective
    CME with EUHFORIA+OpenGGCM
Authors: Scolini, Camilla; Verbeke, Christine; Chané, Emmanuel;
   Zuccarello, Francesco; Poedts, Stefaan; Rodriguez, Luciano; Pomoell,
   Jens; Cramer, William D.; Raeder, Joachim; Gopalswamy, Nat
2018tess.conf10903S    Altcode:
  In this work we perform a Sun-to-Earth comprehensive analysis of the
  July 12, 2012 CME with the aim of testing the space weather predictive
  capabilities of the newly developed EUHFORIA heliospheric model
  integrated with a flux rope model. In order to achieve this goal,
  we make use of a model chain approach by using EUHFORIA outputs at
  Earth as input parameters for the OpenGGCM magnetospheric model. <P
  />We first reconstruct the CME kinematic parameters by means of single-
  and multi- spacecraft reconstruction methods based on coronagraphic and
  heliospheric CME observations. The magnetic field-related parameters
  of the flux-rope are estimated based on imaging observations of the
  photospheric and low coronal source region of the eruption. We then
  simulate the event with EUHFORIA, using both a cone and a flux-rope CME
  model in order to compare the effect of the different CME kinematical
  and magnetic input parameters on simulation results at L1. We compare
  simulations outputs with in-situ observations of the Interplanetary
  CME and we use them as input for the OpenGGCM model, so to investigate
  the magnetospheric response to ICME-driven solar wind perturbations
  modelled with EUHFORIA. We study the ICME-driven geomagnetic storm
  focusing on the predicted geomagnetic activity and compare it with
  actual data records. Finally, we discuss the forecasting capabilities
  of such kind of approach and its future improvements.

---------------------------------------------------------
Title: Interplanetary type II radio bursts: STEREO observations and
    Monte Carlo Simulations
Authors: Krupar, Vratislav; Eastwood, Jonathan P.; Magdalenic, Jasmina;
   Gopalswamy, Nat; Kruparova, Oksana; Szabo, Adam
2018EGUGA..20.9950K    Altcode:
  Coronal mass ejections (CMEs) are responsible for most severe space
  weather events such as solar energetic particle events and geomagnetic
  storms at Earth. Type II radio bursts are slow drifting emissions
  produced by beams of suprathermal electrons accelerated at CME-driven
  MHD shock waves propagating through the corona and interplanetary
  medium. Here, we report a statistical study of 153 interplanetary
  type II radio bursts observed by the two STEREO spacecraft between
  March 2008 and August 2014. The shock associated radio emission
  was compared with CMEs from the HELCATS (Heliospheric Cataloguing,
  Analysis and Techniques Service) catalogue. We found that fast CMEs are
  statistically more likely to be associated with the interplanetary type
  II radio bursts. We have correlated frequency drifts with white-light
  observations in order to localize radio sources with a respect to a CME
  geometry. Our results suggest that interplanetary type II bursts are
  more likely to have a source region situated close to CME flanks than
  close to the CME nose. Finally, we performed Monte Carlo simulations
  to study a role of propagation on a visibility of interplanetary type
  II radio bursts.

---------------------------------------------------------
Title: Sun-to-Earth simulations of geo-effective Coronal Mass
Ejections with EUHFORIA: a heliospheric-magnetospheric model chain
    approach
Authors: Scolini, Camilla; Verbeke, Christine; Poedts, Stefaan;
   Rodriguez, Luciano; Mierla, Marilena; Pomoell, Jens; Cramer, William;
   Raeder, Jimmy; Gopalswamy, Nat
2018EGUGA..20.6441S    Altcode:
  In this work we perform a Sun-to-Earth comprehensive analysis of the
  July 12, 2012 CME with the aim of testing the space weather predictive
  capabilities of the newly developed EUHFORIA heliospheric model
  integrated with a flux rope model. In order to achieve this goal,
  we make use of a model chain approach by using EUHFORIA outputs at
  Earth as input parameters for the OpenGGCM magnetospheric model. We
  first reconstruct the CME kinematic parameters by means of single- and
  multi- spacecraft reconstruction methods based on coronagraphic and
  heliospheric CME observations. The magnetic field-related parameters
  of the flux-rope are estimated based on imaging observations of the
  photospheric and low coronal source region of the eruption. We then
  simulate the event with EUHFORIA, using both a cone and a flux-rope CME
  model in order to compare the effect of the different CME kinematical
  and magnetic input parameters on simulation results at L1. We compare
  simulations outputs with in-situ observations of the Interplanetary
  CME and we use them as input for the OpenGGCM model, so to investigate
  the magnetospheric response to ICME-driven solar wind perturbations
  modelled with EUHFORIA. We study the ICME-driven geomagnetic storm
  focusing on the predicted geomagnetic activity and compare it with
  actual data records. Finally, we discuss the forecasting capabilities
  of such kind of approach and its future improvements.

---------------------------------------------------------
Title: Coronal mass ejections as a new indicator of the active Sun
Authors: Gopalswamy, Nat
2018IAUS..340...95G    Altcode: 2018arXiv180411112G
  Coronal mass ejections (CMEs) have become one of the key indicators
  of solar activity, especially in terms of the consequences of the
  transient events in the heliosphere. Although CMEs are closely related
  to the sunspot number (SSN), they are also related to other closed
  magnetic regions on the Sun such as quiescent filament regions. This
  makes CMEs a better indicator of solar activity. While sunspots mainly
  represent the toroidal component of solar magnetism, quiescent filaments
  (and hence CMEs associated with them) connect the toroidal and poloidal
  components via the rush-to-the-pole (RTTP) phenomenon. Taking the end of
  RTTP in each hemisphere as an indicator of solar polarity reversal, it
  is shown that the north-south reversal asymmetry has a quasi-periodicity
  of 3-5 solar cycles. Focusing on the geospace consequences of CMEs, it
  is shown that the maximum CME speeds averaged over Carrington rotation
  period show good correlation with geomagnetic activity indices such
  as Dst and aa.

---------------------------------------------------------
Title: Physical Conditions in the Solar Corona Derived from the
    Total Solar Eclipse Observations obtained on 2017 August 21 Using
    a Polarization Camera
Authors: Gopalswamy, N.; Yashiro, Seiji; Reginald, Nelson; Thakur,
   Neeharika; Thompson, Barbara J.; Gong, Qian
2018AAS...23122008G    Altcode:
  We present preliminary results obtained by observing the solar corona
  during the 2017 August 21 total solar eclipse using a polarization
  camera mounted on an eight-inch Schmidt-Cassegrain telescope. The
  observations were made from Madras Oregon during 17:19 to 17:21
  UT. Total and polarized brightness images were obtained at four
  wavelengths (385, 398.5, 410, and 423 nm). The polarization camera had a
  polarization mask mounted on a 2048x2048 pixel CCD with a pixel size of
  7.4 microns. The resulting images had a size of 975x975 pixels because
  four neighboring pixels were summed to yield the polarization and total
  brightness images. The ratio of 410 and 385 nm images is a measure
  of the coronal temperature, while that at 423 and 398.5 nm images
  is a measure of the coronal flow speed. We compared the temperature
  map from the eclipse observations with that obtained from the Solar
  Dynamics Observatory’s Atmospheric Imaging Assembly images at six EUV
  wavelengths, yielding consistent temperature information of the corona.

---------------------------------------------------------
Title: A Study of the Interplanetary Signatures of Earth-Arriving CMEs
Authors: Akiyama, S.; Yashiro, S.; Gopalswamy, N.; Xie, H.; Makela,
   P. A.; Kay, C.
2017AGUFMSH51E..06A    Altcode:
  We studied interplanetary (IP) signatures associated with coronal mass
  ejections (CMEs) that are likely to reach Earth. In order to find Earth-
  arriving CMEs, we started with disk-center CMEs originating within 30
  degrees from the central meridian and the equator. Using the side-view
  images from the STEREO mission, we excluded CMEs that faded out before
  reaching the Earth orbit, or were captured by other CMEs, or erupted
  away from the ecliptic plane. We found 61 Earth- arriving CMEs during
  2009/10/01 - 2012/07/31 (inclusive). Though all events were observed
  to reach Earth in the STEREO/HI2 field of view, only 34 out of 61
  events (56%) were associated with magnetic cloud (MC) or ejecta (EJ)
  observed by ACE or Wind. We compared the CME characteristics associated
  with 9 MCs, 25 EJs, and 27 no- clear- signature (NCS) events to find
  out what might cause the difference in the IP signatures. To avoid
  projection effects, we used coronagraph images obtained by the STEREO
  mission. The average speed (width) of CMEs associated with MCs, EJs,
  and NCSs are 484 km/s (104°), 663 km/s (135°), and 595 km/s (144°),
  respectively. CMEs associated with MCs tend to be less energetic than
  other types in our dataset. We also checked the coronal holes (CHs)
  near the CME source to examine the effect of the CME deflection. In the
  case of MCs and EJs, only 22% (2/9) and 28% (7/25) events have CHs near
  the source, while 48% (13/27) NCS events have nearby CHs. We discuss
  what factors near the Sun cause the observed differences at Earth.

---------------------------------------------------------
Title: Sun-to-Earth simulations of geo-effective Coronal Mass
Ejections with EUHFORIA: a heliospheric-magnetospheric model chain
    approach
Authors: Scolini, C.; Verbeke, C.; Gopalswamy, N.; Wijsen, N.; Poedts,
   S.; Mierla, M.; Rodriguez, L.; Pomoell, J.; Cramer, W. D.; Raeder, J.
2017AGUFMSH31A2716S    Altcode:
  Coronal Mass Ejections (CMEs) and their interplanetary counterparts
  are considered to be the major space weather drivers. An accurate
  modelling of their onset and propagation up to 1 AU represents a
  key issue for more reliable space weather forecasts, and predictions
  about their actual geo-effectiveness can only be performed by coupling
  global heliospheric models to 3D models describing the terrestrial
  environment, e.g. magnetospheric and ionospheric codes in the
  first place. In this work we perform a Sun-to-Earth comprehensive
  analysis of the July 12, 2012 CME with the aim of testing the space
  weather predictive capabilities of the newly developed EUHFORIA
  heliospheric model integrated with the Gibson-Low (GL) flux rope
  model. In order to achieve this goal, we make use of a model chain
  approach by using EUHFORIA outputs at Earth as input parameters for the
  OpenGGCM magnetospheric model. We first reconstruct the CME kinematic
  parameters by means of single- and multi- spacecraft reconstruction
  methods based on coronagraphic and heliospheric CME observations. The
  magnetic field-related parameters of the flux rope are estimated based
  on imaging observations of the photospheric and low coronal source
  regions of the eruption. We then simulate the event with EUHFORIA,
  testing the effect of the different CME kinematic input parameters on
  simulation results at L1. We compare simulation outputs with in-situ
  measurements of the Interplanetary CME and we use them as input for
  the OpenGGCM model, so to investigate the magnetospheric response to
  solar perturbations. From simulation outputs we extract some global
  geomagnetic activity indexes and compare them with actual data records
  and with results obtained by the use of empirical relations. Finally,
  we discuss the forecasting capabilities of such kind of approach and
  its future improvements.

---------------------------------------------------------
Title: A Statistical Study of Interplanetary Type II Bursts: STEREO
    Observations
Authors: Krupar, V.; Eastwood, J. P.; Magdalenic, J.; Gopalswamy,
   N.; Kruparova, O.; Szabo, A.
2017AGUFMSH41B2774K    Altcode:
  Coronal mass ejections (CMEs) are the primary cause of the most severe
  and disruptive space weather events such as solar energetic particle
  (SEP) events and geomagnetic storms at Earth. Interplanetary type II
  bursts are generated via the plasma emission mechanism by energetic
  electrons accelerated at CME-driven shock waves and hence identify
  CMEs that potentially cause space weather impact. As CMEs propagate
  outward from the Sun, radio emissions are generated at progressively
  at lower frequencies corresponding to a decreasing ambient solar
  wind plasma density. We have performed a statistical study of 153
  interplanetary type II bursts observed by the two STEREO spacecraft
  between March 2008 and August 2014. These events have been correlated
  with manually-identified CMEs contained in the Heliospheric Cataloguing,
  Analysis and Techniques Service (HELCATS) catalogue. Our results confirm
  that faster CMEs are more likely to produce interplanetary type II radio
  bursts. We have compared observed frequency drifts with white-light
  observations to estimate angular deviations of type II burst propagation
  directions from radial. We have found that interplanetary type II bursts
  preferably arise from CME flanks. Finally, we discuss a visibility of
  radio emissions in relation to the CME propagation direction.

---------------------------------------------------------
Title: Relationship between SEP Peak intensity and CME Acceleration,
    Speed and Width
Authors: Xie, H.; St Cyr, O. C.; Makela, P. A.; Gopalswamy, N.
2017AGUFMSH33C..01X    Altcode:
  We study the large solar energetic particle (SEP) events that were
  detected by GOES in the &gt;10 MeV energy channel during December 2006
  to January 2016. Data used in this study includes the Solar Electron
  Proton Telescope (SEPT) and High Energy Telescopes (HET) on STEREO
  A and B, the Electron, Proton, and Alpha Monitor (EPAM) on ACE,
  and the Energetic and Relativistic Nuclei and Electron instrument
  (ERNE) on SOHO. By choosing the smallest connection angles between
  SEP solar locations and magnetic foot-points of each spacecraft, we
  divide SEP events as SOHO SEPs or STEREO SEPs. We then compute the SEP
  peak intensity I0 at the center of the Gausssian using the Gausssian
  expression from Richardson et al. (2014) and study the relationship
  between SEP electron and proton peak intensity and CME acceleration,
  speed and width. By using I0 derived from multi-spacecraft observations
  we found that the correlations between SEP peak intensity and CME
  acceleration and speed improved. We also found that this correlation
  can be further improved by taking into account the effects of CME width
  and its solar source latitude. The implication for the SEP forecast
  of our obtained results will be discussed.

---------------------------------------------------------
Title: Using the Coronal Evolution to Successfully Forward Model CMEs'
    In Situ Magnetic Profiles
Authors: Kay, C.; Gopalswamy, N.
2017JGRA..12211810K    Altcode: 2017arXiv171003825K
  Predicting the effects of a coronal mass ejection (CME) impact requires
  knowing if impact will occur, which part of the CME impacts, and its
  magnetic properties. We explore the relation between CME deflections
  and rotations, which change the position and orientation of a CME,
  and the resulting magnetic profiles at 1 AU. For 45 STEREO-era,
  Earth-impacting CMEs, we determine the solar source of each CME,
  reconstruct its coronal position and orientation, and perform a
  ForeCAT (Forecasting a CME's Altered Trajectory) simulation of the
  coronal deflection and rotation. From the reconstructed and modeled
  CME deflections and rotations, we determine the solar cycle variation
  and correlations with CME properties. We assume no evolution between
  the outer corona and 1 AU and use the ForeCAT results to drive the
  ForeCAT In situ Data Observer (FIDO) in situ magnetic field model,
  allowing for comparisons with ACE and Wind observations. We do not
  attempt to reproduce the arrival time. On average FIDO reproduces
  the in situ magnetic field for each vector component with an error
  equivalent to 35% of the average total magnetic field strength when the
  total modeled magnetic field is scaled to match the average observed
  value. Random walk best fits distinguish between ForeCAT's ability to
  determine FIDO's input parameters and the limitations of the simple flux
  rope model. These best fits reduce the average error to 30%. The FIDO
  results are sensitive to changes of order a degree in the CME latitude,
  longitude, and tilt, suggesting that accurate space weather predictions
  require accurate measurements of a CME's position and orientation.

---------------------------------------------------------
Title: On the Onset Frequency of Metric Type II Radio Bursts and
    the Longitudinal Extent of the Associated SEP Events
Authors: Makela, P. A.; Gopalswamy, N.; Yashiro, S.; Thakur, N.;
   Akiyama, S.; Xie, H.
2017AGUFMSH33C..04M    Altcode:
  In a recent study Gopalswamy et al. (2017, J. Phys. Conf. Ser.,
  Proc. 16th AIAC) found that the ground level enhancements (GLEs),
  regular solar energetic particle (SEP) events and filament eruption
  (FE) associated SEP events have distinct average starting frequencies of
  the associated type II bursts, although the distributions overlap. They
  also found that the initial acceleration of the coronal mass ejections
  (CMEs) associated with the three groups were distinct. Based on
  these earlier results emphasizing a hierarchical relationship of CME
  kinematics and SEP events, we studied the possible dependence between
  the longitudinal spread of the SEP events and the onset frequency of
  metric type II. The studied &gt;25 MeV SEP events are from the list
  of Richardson et al. (2014, Sol. Phys. 289) covering the first seven
  years of the STEREO mission. However, our preliminary results show
  only a weak correlation between the extent of the SEP event and the
  onset frequency of the metric type II radio burst.

---------------------------------------------------------
Title: Prediction of CMEs and Type II Bursts from Sun to Earth
Authors: Cairns, I. H.; Schmidt, J. M.; Gopalswamy, N.; van der
   Holst, B.
2017AGUFMSH31D..06C    Altcode:
  Most major space weather events are due to fast CMEs and their
  shocks interacting with Earth's magnetosphere. SImilarly, type II
  solar radio bursts are well-known signatures of CMEs and their shocks
  moving through the corona and solar wind. The properties of the space
  weather events and the type II radio bursts depend sensitively on the
  CME velocity, shape, and evolution as functions of position and time,
  as well as on the magnetic field vector in the coronal and solar
  wind plasma, downstream of the CME shock, and inside the CME. We
  report simulations of CMEs and type II bursts from the Sun to Earth
  with the Space Weather Modelling Framework (2015 and 2016 versions),
  set up carefully using relevant data, and a kinetic radio emission
  theory. Excellent agreement between observations, simulations, and
  theory are found for the coronal (metric) type II burst of 7 September
  2014 and associated CME, including the lack of radio emission in the
  solar wind beyond about 10 solar radii. Similarly, simulation of a CME
  and type II burst from the Sun to 1 AU over the period 29 November -
  1 December 2013 yield excellent agreement for the radio burst from 10
  MHz to 30 kHz for STEREO A and B and Wind, arrival of the CME at STEREO
  A within 1 hour reported time, deceleration of the CME in agreement with
  the Gopalswamy et al. [2011] observational analyses, and B<SUB>z</SUB>
  rotations at STEREO A from upstream of the CME shock to within the
  CME. These results provide strong support for the type II theory and
  also that the Space WeatherModeling Framework can accurately predict the
  properties and evolution of CMEs and the interplanetary magnetic field
  and plasma from the Sun to 1 AU when sufficiently carefully initialized.

---------------------------------------------------------
Title: Reproducing the Magnetic Field of Near-Earth ICMEs
Authors: Kay, C.; Gopalswamy, N.
2017AGUFMSH34B..03K    Altcode:
  Understanding the magnetic profile of an ICME is critical for
  predicting its potential effects near Earth. Kay et al. (2017)
  introduced the ForeCAT In situ Data Observer (FIDO), which uses the
  results of a coronal CME deflection and rotation model to orient
  a simple Lundquist force-flux rope, which is then propagated over a
  synthetic spacecraft. This work showed the potential of the FIDO model
  for predicting ICME magnetic field on roughly hourly time scales,
  and that the in situ profiles are very sensitive to precise location
  and orientation of the ICME flux rope. We expand upon this work with a
  recent study of 45 STEREO-era near-Earth CMEs and consider the circular
  flux rope (Nieves-Chinchilla et al. 2016) in addition to the Lundquist
  flux rope. We quantitatively analyze the goodness-of-fit of the FIDO
  fits and determine the circumstances under which the FIDO model performs
  best. Finally, we explore the limitations of the flux rope model itself
  to reproduce the data, versus our ability to determine the appropriate
  values of its free parameters.

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Title: Deflection and Rotation of STEREO-Era CMEs
Authors: Kay, C.; Gopalswamy, N.
2017AGUFMSH51E..03K    Altcode:
  Understanding the location and orientation of CMEs is critical for
  predicting whether they will impact Earth, and what their magnetic
  orientation may be upon impact. This requires accounting for any
  deflection or rotation that may occur as the CME propagates away from
  the Sun. For 45 Earth-directed CMEs occurring between 2007 and 2014,
  all observed by both STEREO spacecraft, we use EUV observations to
  determine the precise initial location, then reconstruct the position
  and orientation in COR1 and COR2 using the GCS technique. Using a
  model for the in situ magnet field we also determine the location and
  orientation near 1 AU. We then simulate the deflection and rotation
  of these CMEs using the ForeCAT model (Kay et al. 2015). We find
  good agreement between the observed and simulated CME deflections and
  rotations. These CMEs span the end of Solar Cycle 23 to the maximum of
  Solar Cycle 24 allowing us to investigate the changes in CME deflection
  and rotation. We find that the magnitude and direction of the deflection
  and rotation are determined by a balance between the changes in the
  background magnetic field and the changes in the CME properties,
  such as the mass and velocity.

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Title: A Sun-to-Earth Analysis of Magnetic Helicity of the 2013
    March 17-18 Interplanetary Coronal Mass Ejection
Authors: Pal, Sanchita; Gopalswamy, Nat; Nandy, Dibyendu; Akiyama,
   Sachiko; Yashiro, Seiji; Makela, Pertti; Xie, Hong
2017ApJ...851..123P    Altcode: 2017arXiv171201114P
  We compare the magnetic helicity in the 2013 March 17-18 interplanetary
  coronal mass ejection (ICME) flux rope at 1 au and in its solar
  counterpart. The progenitor coronal mass ejection (CME) erupted on
  2013 March 15 from NOAA active region 11692 and is associated with
  an M1.1 flare. We derive the source region reconnection flux using
  the post-eruption arcade (PEA) method that uses the photospheric
  magnetogram and the area under the PEA. The geometrical properties of
  the near-Sun flux rope is obtained by forward-modeling of white-light
  CME observations. Combining the geometrical properties and the
  reconnection flux, we extract the magnetic properties of the CME
  flux rope. We derive the magnetic helicity of the flux rope using its
  magnetic and geometric properties obtained near the Sun and at 1 au. We
  use a constant-α force-free cylindrical flux rope model fit to the
  in situ observations in order to derive the magnetic and geometric
  information of the 1 au ICME. We find a good correspondence in both
  amplitude and sign of the helicity between the ICME and the CME,
  assuming a semi-circular (half torus) ICME flux rope with a length of
  π au. We find that about 83% of the total flux rope helicity at 1 au
  is injected by the magnetic reconnection in the low corona. We discuss
  the effect of assuming flux rope length in the derived value of the
  magnetic helicity. This study connecting the helicity of magnetic flux
  ropes through the Sun-Earth system has important implications for the
  origin of helicity in the interplanetary medium and the topology of
  ICME flux ropes at 1 au and hence their space weather consequences.

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Title: Prominence Eruption Initiated by Helical Kink Instability of
    an Embedded Flux Rope
Authors: Vemareddy, P.; Gopalswamy, N.; Ravindra, B.
2017ApJ...850...38V    Altcode: 2017arXiv170910035V
  We study the triggering mechanism of a limb-prominence eruption and
  the associated coronal mass ejection (CME) near AR 12342 using Solar
  Dynamics Observatory and Large Angle and Spectrometric Coronagraph/Solar
  Heliospheric Observatory observations. The prominence is seen with an
  embedded flux thread (FT) at one end and bifurcates from the middle to
  a different footpoint location. The morphological evolution of the FT
  is similar to that of an unstable flux rope (FR), which we regard as
  a prominence-embedded FR. The FR twist exceeds the critical value. In
  addition, the morphology of the prominence plasma in 304 Å images marks
  the helical nature of the magnetic skeleton, with a total of 2.96 turns
  along arc length. The potential field extrapolation model indicates that
  the critical height of the background magnetic field gradient falls
  within the inner corona (105 Mm), which is consistent with the extent
  of coronal plasma loops. These results suggest that the helical kink
  instability in the embedded FR caused the slow rise of the prominence to
  the height of the torus instability domain. Moreover, the differential
  emission measure analysis unveils heating of the prominence plasma to
  coronal temperatures during an eruption, suggesting reconnection-related
  heating underneath the upward rising embedded FR. The prominence starts
  with a slow rise motion of 10 km s<SUP>-1</SUP>, which is followed by
  fast and slow acceleration phases that have an average acceleration of
  28.9 m s<SUP>-2 </SUP>and 2.4 m s<SUP>-2</SUP> in C2 and C3 field of
  view, respectively. As predicted by previous numerical simulations, the
  observed synchronous kinematic profiles of the CME leading edge and the
  core support the involved FR instability in the prominence initiation.

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Title: Toward a Next Generation Solar Coronagraph: Development of
    a Compact Diagnostic Coronagraph on the ISS
Authors: Cho, K. -S.; Bong, S. -C.; Choi, S.; Yang, H.; Kim, J.;
   Baek, J. -H.; Park, J.; Lim, E. -K.; Kim, R. -S.; Kim, S.; Kim,
   Y. -H.; Park, Y. -D.; Clarke, S. W.; Davila, J. M.; Gopalswamy, N.;
   Nakariakov, V. M.; Li, B.; Pinto, R. F.
2017JKAS...50..139C    Altcode:
  The Korea Astronomy and Space Science Institute plans to develop
  a coronagraph in collaboration with National Aeronautics and Space
  Administration (NASA) and to install it on the International Space
  Station (ISS). The coronagraph is an externally occulted one-stage
  coronagraph with a field of view from 3 to 15 solar radii. The
  observation wavelength is approximately 400 nm, where strong Fraunhofer
  absorption lines from the photosphere experience thermal broadening and
  Doppler shift through scattering by coronal electrons. Photometric
  filter observations around this band enable the estimation of
  2D electron temperature and electron velocity distribution in the
  corona. Together with a high time cadence (&lt;12 min) of corona images
  used to determine the geometric and kinematic parameters of coronal
  mass ejections, the coronagraph will yield the spatial distribution
  of electron density by measuring the polarized brightness. For the
  purpose of technical demonstration, we intend to observe the total
  solar eclipse in August 2017 with the filter system and to perform a
  stratospheric balloon experiment in 2019 with the engineering model
  of the coronagraph. The coronagraph is planned to be installed on the
  ISS in 2021 for addressing a number of questions (e.g., coronal heating
  and solar wind acceleration) that are both fundamental and practically
  important in the physics of the solar corona and of the heliosphere.

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Title: Extreme Solar Eruptions and their Space Weather Consequences
Authors: Gopalswamy, Nat
2017arXiv170903165G    Altcode:
  Solar eruptions generally refer to coronal mass ejections (CMEs)
  and flares. Both are important sources of space weather. Solar flares
  cause sudden change in the ionization level in the ionosphere. CMEs
  cause solar energetic particle (SEP) events and geomagnetic storms. A
  flare with unusually high intensity and/or a CME with extremely
  high energy can be thought of examples of extreme events on the
  Sun. These events can also lead to extreme SEP events and/or geomagnetic
  storms. Ultimately, the energy that powers CMEs and flares are stored in
  magnetic regions on the Sun, known as active regions. Active regions
  with extraordinary size and magnetic field have the potential to
  produce extreme events. Based on current data sets, we estimate the
  sizes of one-in-hundred and one-in-thousand year events as an indicator
  of the extremeness of the events. We consider both the extremeness in
  the source of eruptions and in the consequences. We then compare the
  estimated 100-year and 1000-year sizes with the sizes of historical
  extreme events measured or inferred.

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Title: A Hierarchical Relationship between the Fluence Spectra and
CME Kinematics in Large Solar Energetic Particle Events: A Radio
    Perspective
Authors: Gopalswamy, N.; Mäkelä, P.; Yashiro, S.; Thakur, N.;
   Akiyama, S.; Xie, H.
2017JPhCS.900a2009G    Altcode: 2017arXiv170700209G
  We report on further evidence that solar energetic particles are
  organized by the kinematic properties of coronal mass ejections
  (CMEs)[1]. In particular, we focus on the starting frequency of type II
  bursts, which is related to the distance from the Sun where the radio
  emission starts. We find that the three groups of solar energetic
  particle (SEP) events known to have distinct values of CME initial
  acceleration, also have distinct average starting frequencies of the
  associated type II bursts. SEP events with ground level enhancement
  (GLE) have the highest starting frequency (107 MHz), while those
  associated with filament eruption (FE) in quiescent regions have the
  lowest starting frequency (22 MHz); regular SEP events have intermediate
  starting frequency (81 MHz). Taking the onset time of type II bursts as
  the time of shock formation, we determine the shock formation heights
  measured from the Sun center. We find that the shocks form on average
  closest to the Sun (1.51 Rs) in GLE events, farthest from the Sun
  in FE SEP events (5.38 Rs), and at intermediate distances in regular
  SEP events (1.72 Rs). Finally, we present the results of a case study
  of a CME with high initial acceleration (∼3 km s<SUP>-2</SUP>) and
  a type II radio burst with high starting frequency (∼200 MHz) but
  associated with a minor SEP event. We find that the relation between
  the fluence spectral index and CME initial acceleration continues to
  hold even for this minor SEP event.

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Title: CME Velocity and Acceleration Error Estimates Using the
    Bootstrap Method
Authors: Michalek, Grzegorz; Gopalswamy, Nat; Yashiro, Seiji
2017SoPh..292..114M    Altcode:
  The bootstrap method is used to determine errors of basic attributes of
  coronal mass ejections (CMEs) visually identified in images obtained by
  the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and
  Spectrometric Coronagraph (LASCO) instruments. The basic parameters of
  CMEs are stored, among others, in a database known as the SOHO/LASCO
  CME catalog and are widely employed for many research studies. The
  basic attributes of CMEs (e.g. velocity and acceleration) are obtained
  from manually generated height-time plots. The subjective nature of
  manual measurements introduces random errors that are difficult to
  quantify. In many studies the impact of such measurement errors is
  overlooked. In this study we present a new possibility to estimate
  measurements errors in the basic attributes of CMEs. This approach is
  a computer-intensive method because it requires repeating the original
  data analysis procedure several times using replicate datasets. This
  is also commonly called the bootstrap method in the literature. We
  show that the bootstrap approach can be used to estimate the errors
  of the basic attributes of CMEs having moderately large numbers of
  height-time measurements. The velocity errors are in the vast majority
  small and depend mostly on the number of height-time points measured
  for a particular event. In the case of acceleration, the errors are
  significant, and for more than half of all CMEs, they are larger than
  the acceleration itself.

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Title: Comparison of the coronal mass ejection shock acceleration
    of three widespread SEP events during solar cycle 24
Authors: Xie, H.; Mäkelä, P.; St. Cyr, O. C.; Gopalswamy, N.
2017JGRA..122.7021X    Altcode:
  We studied three solar energetic particle (SEP) events observed on 14
  August 2010, 3 November 2011, and 5 March 2013 by Solar Terrestrial
  Relations Observatory (STEREO) A, B, and near-Earth (L1) spacecraft
  with a longitudinal distribution of particles &gt;90°. Using
  a forward modeling method combined with extreme ultraviolet and
  white-light images, we determined the angular extent of the shock,
  the time and location (cobpoint) of the shock intersection with
  the magnetic field line connecting to each spacecraft, and compute
  the shock speed at the cobpoint of each spacecraft. We then examine
  whether the observations of SEPs at each spacecraft were accelerated
  and injected by the spatially extended shocks or whether another
  mechanism such as cross-field transport is required for an alternative
  explanation. Our analyses results indicate that the SEPs observed
  at the three spacecraft on 3 November, STEREO B (STB) and L1 on 14
  August, and the 5 March SEP event at STEREO A (STA) can be explained
  by the direct shock acceleration. This is consistent with the observed
  significant anisotropies, short time delays between particle release
  times and magnetic connection times, and sharp rises in the SEP
  time profiles. Cross-field diffusion is the likely cause for the 14
  August SEP event observed by STA and the 5 March SEPs observed by STB
  and L1 spacecraft, as particle observations featured weak electron
  aniotropies and slow rising intensity profiles. Otherwise, the wide
  longitudinal spread of these SEP increases would require an existence
  of a circumsolar shock, which may not be a correct assumption in the
  corona and heliosphere.

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Title: New Evidence for a Coronal Mass Ejection-driven High Frequency
    Type II Burst near the Sun
Authors: Kumari, Anshu; Ramesh, R.; Kathiravan, C.; Gopalswamy, N.
2017ApJ...843...10K    Altcode:
  We report observations of the high frequency type II radio burst
  (≈430-30 MHz) that occurred in the solar corona on 2015 November
  4. The drift rate of the burst, estimated close to the start frequency
  of its fundamental component (≈215 MHz), is unusually high (≈2
  MHz s<SUP>-1</SUP>). Our analysis shows that the estimated speed
  of the magnetohydrodynamic shock driver of the burst varies with
  time. The peak speed and acceleration are very large, ≈ 2450
  {km} {{{s}}}<SUP>-1</SUP> and ≈ 17 {km} {{{s}}}<SUP>-2</SUP>,
  respectively. There is spatio-temporal correlation between the type II
  burst and the associated coronal mass ejection (CME) in the whitelight
  and extreme-ultraviolet images. The time profile of the shock speed and
  the light curve of the associated soft X-ray flare correlate well. These
  results indicate that in the present case, (I) the magnetohydrodynamic
  shock responsible for the high frequency coronal type II burst is driven
  by the CME and (II) the time profile of the type II burst shock speed
  represents the near-Sun kinematics of the CME.

---------------------------------------------------------
Title: Direction Finding Analysis of the 2012 July 6 Radio Burst
Authors: Makela, Pertti; Gopalswamy, Nat; Akiyama, Sachiko
2017shin.confE.141M    Altcode:
  The 2012 July 6 X1.1 flare at S13W59 and a halo CME with a space
  speed of 1900 km/s were associated with type III and type II radio
  bursts. The metric-to-decametric type II radio burst extended down to 5
  MHz. Simultaneously a slowly drifting feature with a harmonic structure
  was observed by Wind and STEREO radio receivers around and below 1 MHz,
  above the strong type III radio burst at lower frequencies. The radio
  direction finding analysis of this interplanetary (IP) type II radio
  burst indicates that the radio source was located near the nose and
  towards the southern flank of the CME-driven shock. This results is
  in accordance with previous suggestions that when the metric and IP
  type II burst are overlapping, the IP type II radio burst originates
  near the shock nose, whereas the source of the metric type II burst
  is closer to the Sun in the shock flank region.

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Title: Observations and Simulations of the Sun-to-Earth Evolution
    of a STEREO-Era Set of Earth-Impacting CMEs and their In Situ
    Magnetic Field
Authors: Kay, Christina; Gopalswamy, Nat
2017shin.confE..20K    Altcode:
  Coronal mass ejections (CMEs) drive extreme space weather events
  throughout the solar system. Predicting the effects of a CME impact
  requires knowing not only if a CME will impact a given point, but also
  which part of the CME impacts, and what its magnetic properties are upon
  impact. We explore the relation between CME deflections and rotations,
  which change the position and orientation of a CME, and the resulting
  magnetic profiles at 1 AU. For 45 STEREO-era, Earth-impacting CMEs, we
  determine the region from which each CME erupts, reconstruct its coronal
  position and orientation, and perform a ForeCAT (Kay et al. 2015)
  simulation of the coronal deflection and rotation. From this large set
  of reconstructed and modeled CME deflections and rotations we determine
  variations in the behavior over the solar cycle as well as correlations
  with CME properties. We then couple the ForeCAT results with the FIDO in
  situ magnetic field model (Kay et al. 2017), allowing for comparisons
  with ACE and Wind observations. FIDO successfully reproduces the in
  situ magnetic field for all but three of the CMEs. From random walk best
  fits, we distinguish between ForeCAT's ability to determine FIDO's input
  parameters, and the limitations of using a simple flux rope model to
  reproduce complicated in situ structures. We find that the FIDO results
  are quite sensitive to changes of order a degree in the CME latitude,
  longitude, and tilt, suggesting that accurate space weather predictions
  require accurate measurements of a CME's position and orientation.

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Title: Deflection and Rotation of CMEs from Active Region 11158
Authors: Kay, Christina; Gopalswamy, Nat; Xie, Hong; Yashiro, Seiji
2017SoPh..292...78K    Altcode: 2017arXiv170407694K
  Between 13 and 16 February 2011, a series of coronal mass ejections
  (CMEs) erupted from multiple polarity inversion lines within
  active region 11158. For seven of these CMEs we employ the graduated
  cylindrical shell (GCS) flux rope model to determine the CME trajectory
  using both Solar Terrestrial Relations Observatory (STEREO) extreme
  ultraviolet (EUV) and coronagraph images. We then use the model called
  Forecasting a CME's Altered Trajectory (ForeCAT) for nonradial CME
  dynamics driven by magnetic forces to simulate the deflection and
  rotation of the seven CMEs. We find good agreement between ForeCAT
  results and reconstructed CME positions and orientations. The
  CME deflections range in magnitude between 10<SUP>∘</SUP> and
  30<SUP>∘</SUP>. All CMEs are deflected to the north, but we find
  variations in the direction of the longitudinal deflection. The
  rotations range between 5<SUP>∘</SUP> and 50<SUP>∘</SUP> with both
  clockwise and counterclockwise rotations. Three of the CMEs begin with
  initial positions within 2<SUP>∘</SUP> from one another. These three
  CMEs are all deflected primarily northward, with some minor eastward
  deflection, and rotate counterclockwise. Their final positions and
  orientations, however, differ by 20<SUP>∘</SUP> and 30<SUP>∘</SUP>,
  respectively. This variation in deflection and rotation results from
  differences in the CME expansion and radial propagation close to the
  Sun, as well as from the CME mass. Ultimately, only one of these seven
  CMEs yielded discernible in situ signatures near Earth, although the
  active region faced toward Earth throughout the eruptions. We suggest
  that the differences in the deflection and rotation of the CMEs can
  explain whether each CME impacted or missed Earth.

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Title: Cataloguing radio emission associated with coronal mass
ejections: results from the HELCATS project
Authors: Eastwood, Jonathan; Krupar, Vratislav; Magdalenic, Jasmina;
   Bisi, Mario; Gopalswamy, Nat; Davies, Jackie; Harrison, Richard;
   Barnes, David
2017EGUGA..19.5249E    Altcode:
  The goal of the Heliospheric Cataloguing, Analysis and Techniques
  Service (HELCATS) is to add value to the STEREO dataset by cataloguing
  the properties of coronal mass ejections and corotating interaction
  regions observed by STEREO. As part of this work, the complementary
  nature of radio measurements and white light observations has been
  assessed. Here we report on the cataloguing of slowly-drifting radio
  emission observed by STEREO WAVES in conjunction with events identified
  in the HELCATS manually-generated coronal mass ejection catalogue. We
  present preliminary statistical results derived from the catalogue,
  in particular the extent to which radio emission is more likely to
  occur in conjunction with fast coronal mass ejections. We further use
  the catalogue to make an initial assessment of the angular deviation
  between radio emission and coronal mass ejection motion, in order to
  determine which part of the coronal mass ejection contributes most to
  the radio emission. HELCATS is project 606692 of the European Union's
  Seventh Framework Programme.

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Title: Estimation of Reconnection Flux Using Post-eruption Arcades
    and Its Relevance to Magnetic Clouds at 1 AU
Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Xie, H.
2017SoPh..292...65G    Altcode: 2017arXiv170101943G
  We report on a new method to compute the flare reconnection (RC)
  flux from post-eruption arcades (PEAs) and the underlying photospheric
  magnetic fields. In previous works, the RC flux has been computed using
  the cumulative flare ribbon area. Here we obtain the RC flux as the flux
  in half of the area underlying the PEA in EUV imaged after the flare
  maximum. We apply this method to a set of 21 eruptions that originated
  near the solar disk center in Solar Cycle 23. We find that the RC flux
  from the arcade method (Φ<SUB>rA</SUB>) has excellent agreement with
  the flux from the flare-ribbon method (Φ<SUB>rR</SUB>) according to
  Φ<SUB>rA</SUB>=1.24 (Φ<SUP>r<SUB>R</SUB>) 0.99</SUP>. We also find
  Φ<SUB>rA</SUB> to be correlated with the poloidal flux (Φ<SUB>P</SUB>)
  of the associated magnetic cloud at 1 AU: Φ<SUB>P</SUB>=1.20
  (Φ<SUP>r<SUB>A</SUB>) 0.85</SUP>. This relation is nearly identical
  to that obtained by Qiu et al. (Astrophys. J. 659, 758, 2007) using
  a set of only 9 eruptions. Our result supports the idea that flare
  reconnection results in the formation of the flux rope and PEA as a
  common process.

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Title: A Close Connection between Flares and Coronal Mass Ejections
    Revealed by the Reconnected Flux in the Solar Source Region
Authors: Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Xie, Hong
2017EGUGA..1918101G    Altcode:
  We report on a study of the properties of flares and coronal mass
  ejections (CMEs) associated with interplanetary CMEs (ICMEs) detected
  close to Earth. The study is based on a set of magnetic clouds (MCs)
  and non-cloud ejecta (EJ) originating very close to the solar disk. We
  computed the total reconnected flux in each of the associated solar
  eruptions and compared it with the CME, flare, and ICME properties. We
  find that the reconnection flux is closely related to the parameters
  describing the three phenomena. By fitting flux ropes to the coronagraph
  data, we show that the CME magnetic field in the corona is significantly
  higher than the ambient magnetic field. The radial dependence of the
  Flux-rope magnetic field is faster than that of the ambient magnetic
  field. This technique provides a simple method to predict the magnetic
  properties of ICMEs at various destination in the heliosphere.

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Title: Predicting the Magnetic Field of Earth-impacting CMEs
Authors: Kay, C.; Gopalswamy, N.; Reinard, A.; Opher, M.
2017ApJ...835..117K    Altcode:
  Predicting the impact of coronal mass ejections (CMEs) and the southward
  component of their magnetic field is one of the key goals of space
  weather forecasting. We present a new model, the ForeCAT In situ Data
  Observer (FIDO), for predicting the in situ magnetic field of CMEs. We
  first simulate a CME using ForeCAT, a model for CME deflection and
  rotation resulting from the background solar magnetic forces. Using
  the CME position and orientation from ForeCAT, we then determine the
  passage of the CME over a simulated spacecraft. We model the CME’s
  magnetic field using a force-free flux rope and we determine the in
  situ magnetic profile at the synthetic spacecraft. We show that FIDO
  can reproduce the general behavior of four observed CMEs. FIDO results
  are very sensitive to the CME’s position and orientation, and we
  show that the uncertainty in a CME’s position and orientation from
  coronagraph images corresponds to a wide range of in situ magnitudes
  and even polarities. This small range of positions and orientations
  also includes CMEs that entirely miss the satellite. We show that two
  derived parameters (the normalized angular distance between the CME
  nose and satellite position and the angular difference between the
  CME tilt and the position angle of the satellite with respect to the
  CME nose) can be used to reliably determine whether an impact or miss
  occurs. We find that the same criteria separate the impacts and misses
  for cases representing all four observed CMEs.

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Title: A Hierarchical Relationship between CME Properties and the
    Fluence Spectral Index of Large Solar Energetic Particle Events
Authors: Gopalswamy, N.; Yashiro, Seiji; Thakur, Neeharika; Makela,
   Pertti; Xie, Hong; Akiyama, Sachiko
2017AAS...22932503G    Altcode:
  We report on a hierarchical relationship found between properties of
  white-light coronal mass ejections (CMEs) and the fluence spectral
  indices of the associated Large Solar Energetic Particle (SEP)
  Events. We consider 74 large SEP events from the western hemisphere
  in solar cycles 23 and 24 by multiple spacecraft (SAMPEX, GOES, and
  STEREO). The associated CMEs are observed by SOHO. We find that CMEs
  with high initial acceleration are associated with SEP events with the
  hardest fluence spectra, while those with lowest initial acceleration
  have SEP events with the softest fluence spectra; CMEs with intermediate
  initial acceleration result in SEP events with moderately hard fluence
  spectra. Impulsive acceleration leading to high CME speeds close to
  the Sun results in shock formation close to the Sun, where the ambient
  magnetic field and density are high and the particles are energized more
  efficiently. Slowly accelerating CMEs drive shocks at large distances
  from the Sun, where the magnetic field and density have fallen off
  significantly, reducing the efficiency of shock acceleration. These
  opposite extremes are represented by ground level enhancement (GLE)
  events that have high speeds early on (high initial acceleration) and
  the SEP events associated with CMEs from quiescent filament region
  that have low early speeds (low initial acceleration). This finding
  strongly supports the idea that CME-driven shocks accelerate SEPs and
  the heliocentric distance where the acceleration takes place decides
  the hardness of the SEP fluence spectrum.

---------------------------------------------------------
Title: CME association rate of solar flares in cycles 23 and 24
Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.; Makela, P. A.;
   Masuda, S.
2016AGUFMSH13C2320Y    Altcode:
  We report on the solar cycle variation of coronal mass ejection (CME)
  association rate of solar flares in cycles 23 and 24. There were 1,442
  and 707 M flares in the cycles 23 and 24, respectively. We examine the
  CME associations of these flares using SOHO/LASCO and STEREO/SECCHI/COR1
  images. Because the CME association rate increases with the soft X-ray
  flare size, we examined the CME association rate for a given flare
  size. We found that the CME association of the M1 flares was 43% in
  the cycle 23 and decreased to 33% in the cycle 24. The same trend was
  found in the M2 (57% vs 50%) and M3-M5 flares (61% vs 55%). A supporting
  observation is that the average decay time of the M1 flares was 14.3
  min in the cycle 23 and 12.2 min in the cycle 24, indicating a decrease
  of long-duration-event (LDE) flares, which are closely related to the
  CMEs. We also found that the fraction of CME-poor active regions (ARs)
  was 13% (11 out of 87 ARs) in the cycle 23 and 22% (10 out of 45 ARs)
  in the cycle 24. These results suggest that the performance of the CME
  prediction algorithms based on the cycle 23 data could be degraded in
  the cycle 24.

---------------------------------------------------------
Title: Statistical Analysis of Periodic Oscillations in LASCO Coronal
    Mass Ejection Speeds
Authors: Michalek, G.; Shanmugaraju, A.; Gopalswamy, N.; Yashiro,
   S.; Akiyama, S.
2016SoPh..291.3751M    Altcode: 2016SoPh..tmp..165M
  A large set of coronal mass ejections (CMEs, 3463) has been selected to
  study their periodic oscillations in speed in the Solar and Heliospheric
  Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph
  (LASCO) field of view. These events, reported in the SOHO/LASCO catalog
  in the period of time 1996 - 2004, were selected based on having at
  least 11 height-time measurements. This selection criterion allows us
  to construct at least ten-point speed-distance profiles and evaluate
  kinematic properties of CMEs with a reasonable accuracy. To identify
  quasi-periodic oscillations in the speed of the CMEs a sinusoidal
  function was fitted to speed-distance profiles and the speed-time
  profiles. Of the considered events 22 % revealed periodic velocity
  fluctuations. These speed oscillations have on average amplitude
  equal to 87 kms−<SUP>1</SUP> and period 7.8 R<SUB>⊙</SUB>/241 min
  (in distance/time). The study shows that speed oscillations are a
  common phenomenon associated with CME propagation implying that all
  the CMEs have a similar magnetic flux-rope structure. The nature of
  oscillations can be explained in terms of magnetohydrodynamic (MHD)
  waves excited during the eruption process. More accurate detection of
  these modes could, in the future, enable us to characterize magnetic
  structures in space (space seismology).

---------------------------------------------------------
Title: Erratum: Erratum to: Dynamics of CMEs in the LASCO Field
    of View
Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S.; Bronarska, K.
2016SoPh..291.3869M    Altcode: 2016SoPh..tmp..159M
  No abstract at ADS

---------------------------------------------------------
Title: The 2012 July 23 Backside Eruption: An Extreme Energetic
    Particle Event?
Authors: Gopalswamy, N.; Yashiro, S.; Thakur, N.; Mäkelä, P.; Xie,
   H.; Akiyama, S.
2016ApJ...833..216G    Altcode: 2016arXiv161005790G
  The backside coronal mass ejection (CME) of 2012 July 23 had a
  short Sun-to-Earth shock transit time (18.5 hr). The associated solar
  energetic particle (SEP) event had a &gt;10 MeV proton flux peaking at
  ∼5000 pfu, and the energetic storm particle event was an order of
  magnitude larger, making it the most intense event in the space era
  at these energies. By a detailed analysis of the CME, shock, and SEP
  characteristics, we find that the July 23 event is consistent with
  a high-energy SEP event (accelerating particles to gigaelectronvolt
  energies). The times of maximum and fluence spectra in the range 10-100
  MeV were very hard, similar to those of ground-level enhancement (GLE)
  events. We found a hierarchical relationship between the CME initial
  speeds and the fluence spectral indices: CMEs with low initial speeds
  had SEP events with the softest spectra, while those with the highest
  initial speeds had SEP events with the hardest spectra. CMEs attaining
  intermediate speeds result in moderately hard spectra. The July 23 event
  was in the group of hard-spectrum events. During the July 23 event,
  the shock speed (&gt;2000 km s<SUP>-1</SUP>), the initial acceleration
  (∼1.70 km s<SUP>-2</SUP>), and the shock-formation height (∼1.5
  solar radii) were all typical of GLE events. The associated type II
  burst had emission components from meter to kilometer wavelengths,
  suggesting a strong shock. These observations confirm that the 2012
  July 23 event is likely to be an extreme event in terms of the energetic
  particles it accelerated.

---------------------------------------------------------
Title: HELCATS: Statistical results on interplanetary type II bursts
    observed by STEREO/Waves
Authors: Krupar, V.; Eastwood, J. P.; Magdalenic, J.; Gopalswamy,
   N.; Bisi, M. M.; Davies, J. A.; Harrison, R. A.; Barnes, D.
2016AGUFMSH11C2246K    Altcode:
  Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS)
  is a project of the European Union's Seventh Framework Programme. The
  current version of the HELCATS manually-generated Coronal Mass Ejection
  (CME) catalogue contains more than 1,300 CMEs observed between 2007
  and 2014. CMEs are sometimes associated with the so called type II
  bursts which are considered to be radio signatures of fast electrons
  accelerated at the CME-driven shock front. We present statistical
  results on 153 type II bursts associated with manually-identified
  CMEs in the HELCATS catalogue. We found that faster CMEs are more
  likely to produce radio emissions. By comparing frequency drifts with
  white-light observations we calculated angular deviations of type II
  burst propagation directions from radial. Our results confirm that
  type II bursts statistically arise from CME flanks. We also discuss
  the use of interplanetary radio emission in the context of space
  weather forecasting.

---------------------------------------------------------
Title: Comparison on the CME-shock Acceleration of Three Widespread
    SEPs during Solar Cycle 24
Authors: St Cyr, O. C.; Xie, H.; Pertti, M.; Gopalswamy, N.
2016AGUFMSH41B2534S    Altcode:
  Using forward-modeling of three-dimensional (3D) flux rope plus oblate
  spheroid shock model, we analyze three solar energetic particle (SEP)
  events observed in three views by STEREO and SOHO spacecraft. The three
  SEP events occurred on August 14, 2010, November 03, 2011, and March 05,
  2013. All three SEP events show widespread distribution in longitude
  (&gt; 90 degree) but with different onset delays, rate of flux increase,
  and electron anisotropies. By fitting the 3D flux rope + shock model
  to white-light and EUV images from STEREO, SOHO and SDO, we are able to
  best determine the 3D shape of the CME shock wave. The forward-modeling
  technique constrained with multi-spacecraft observations allowed
  us to determine the locations where the shock fronts intersect the
  magnetic footpoints of three spacecraft (STA, B and ACE/Wind), and
  compute the shock speeds and expansion speeds at the intersecting
  points. Our fitting results show that the November 03, 2011 SEP has
  the fastest expansion speed among three events, which is consistent
  with the rapid flux rises at all three spacecraft and small onset
  delay between well-connected STA and poor-connected STB and ACE/Wind
  ( 30 min). On the other hand, the March 05, 2013 SEP has the largest
  shock leading-edge speed thus the largest electron intensity. However,
  due to its relatively weak expansion, the shock ceased expanding at 100
  degree. The intensity observed by ACE/EPAM and Wind/3DP ( 140 degree
  away from the SEP solar source) rose very slowly with a large delay
  of 5 hr, which cannot be explained by the shock acceleration. For the
  Aug. 14, 2010 event, the SEP observed at STB and ACE/Wind are shown
  to be accelerated and injected by the shock and consistent with the
  large anisotropies observed at these two locations. The cross-field
  diffusion is the likely cause of the Aug. 14, 2010 SEP event observed
  by STA and the March 05, 2013 event observed by STB and ACE/Wind,
  which show almost no anisotropy. This investigation helps explore the
  relative importance of the various mechanisms of SEP acceleration.

---------------------------------------------------------
Title: The ForeCAT In Situ Data Observer and the Effects of Deflection
    and Rotation on CME Geoeffectiveness
Authors: Kay, C.; Gopalswamy, N.; Reinard, A.; Opher, M.;
   Nieves-Chinchilla, T.
2016AGUFMSH13B2298K    Altcode:
  CMEs drive the strongest space weather events at Earth and throughout
  the solar system. At Earth, the amount of southward magnetic field in a
  CME is a major component in determining the severity of an impact. We
  present results from ForeCAT (Forecasting a CME's Altered Trajectory,
  Kay et al. 2015), which predicts the deflection and rotation of
  CMEs based on magnetic forces determined by the background magnetic
  field. Understanding these deflections and rotations is essential to
  understanding the geoeffectiveness of CMEs as it determines whether a
  CME will hit Earth and the orientation of the flux rope magnetic field
  upon impact. Using the CME location and orientation from ForeCAT and
  simple flux rope models we show that we can reproduce the in situ
  magnetic profiles of Earth-impacting CMEs with the new ForeCAT In
  situ Data Observer (FIDO). We compare these results with the in situ
  profiles obtained assuming that no deflection or rotation occurs, and
  find that including these nonradial effects is essential for accurate
  space weather forecasting. For several observed cases we comment on
  how the deflection and rotation affects the southward component of
  the CME's magnetic field, and therefore the CME's geoeffectiveness.

---------------------------------------------------------
Title: Shock Formation, Energetic Particle Release, and Kinematics
    of Coronal Mass Ejections
Authors: Gopalswamy, N.; Yashiro, S.; Thakur, N.; Makela, P. A.; Xie,
   H.; Akiyama, S.
2016AGUFMSH32A..06G    Altcode:
  There are many source and environmental parameters that affect the
  characteristics of large solar energetic particle (SEP) events. We
  report on three primary characteristics that seem to determine whether
  a CME-driven shock can accelerate particles to very high energies. The
  first one is the height of shock formation, as indicated by type II
  radio bursts. For SEP events with GeV particles, the shocks form
  very close to the Sun, about half a solar radius above the solar
  surface. For events from filament eruptions (FEs) outside active
  regions, the shock forms at much larger heights - either in the outer
  corona or in the interplanetary medium. The second characteristic
  is the acceleration profile of CMEs. In high-energy particle events,
  the associated CMEs accelerate impulsively (initial acceleration is 2
  km/s/s), ensuring strong shocks very close to the solar surface where
  the ambient magnetic field is high. In FE SEP events, the acceleration
  is typically an order of magnitude smaller, consistent with shock
  formation at large distances from the Sun. The third factor is the
  Alfven speed profile in the ambient medium. It is well known that the
  Alfven speed (or magnetosonic speed) in the corona increases from 300
  km/s in the region where shocks typically form to several hundred km/s
  around 3 solar radii. After that the characteristic speed steadily
  declines. The behavior of the CME speed profile with respect to the
  Alfven speed profile essentially determines the true strength of the
  shock. One of the observational consequences of these three factors
  is the 10-100 MeV spectral index of the SEP events. We show that the
  high-energy SEP events and FE SEP events fall on the opposite ends of
  the distribution of the spectral index: 2 and &gt;4, respectively.

---------------------------------------------------------
Title: History and development of coronal mass ejections as a key
    player in solar terrestrial relationship
Authors: Gopalswamy, N.
2016GSL.....3....8G    Altcode: 2016arXiv160203665G
  Coronal mass ejections (CMEs) are relatively a recently discovered
  phenomenon—in 1971, some 15 years into the Space Era. It took another
  two decades to realize that CMEs are the most important players in
  solar terrestrial relationship as the root cause of severe weather
  in Earth's space environment. CMEs are now counted among the major
  natural hazards because they cause large solar energetic particle
  (SEP) events and major geomagnetic storms, both of which pose danger
  to humans and their technology in space and ground. Geomagnetic storms
  discovered in the 1700s, solar flares discovered in the 1800s, and SEP
  events discovered in the 1900s are all now found to be closely related
  to CMEs via various physical processes occurring at various locations
  in and around CMEs, when they interact with the ambient medium. This
  article identifies a number of key developments that preceded the
  discovery of white-light CMEs suggesting that CMEs were waiting to be
  discovered. The last two decades witnessed an explosion of CME research
  following the launch of the Solar and Heliospheric Observatory mission
  in 1995, resulting in the establishment of a full picture of CMEs.

---------------------------------------------------------
Title: Constraining the Solar Coronal Magnetic Field Strength using
    Split-band Type II Radio Burst Observations
Authors: Kishore, P.; Ramesh, R.; Hariharan, K.; Kathiravan, C.;
   Gopalswamy, N.
2016ApJ...832...59K    Altcode:
  We report on low-frequency radio (85-35 MHz) spectral observations
  of four different type II radio bursts, which exhibited
  fundamental-harmonic emission and split-band structure. Each of the
  bursts was found to be closely associated with a whitelight coronal
  mass ejection (CME) close to the Sun. We estimated the coronal magnetic
  field strength from the split-band characteristics of the bursts, by
  assuming a model for the coronal electron density distribution. The
  choice of the model was constrained, based on the following criteria:
  (1) when the radio burst is observed simultaneously in the upper and
  lower bands of the fundamental component, the location of the plasma
  level corresponding to the frequency of the burst in the lower band
  should be consistent with the deprojected location of the leading edge
  (LE) of the associated CME; (2) the drift speed of the type II bursts
  derived from such a model should agree closely with the deprojected
  speed of the LE of the corresponding CMEs. With the above conditions,
  we find that: (1) the estimated field strengths are unique to each
  type II burst, and (2) the radial variation of the field strength in
  the different events indicate a pattern. It is steepest for the case
  where the heliocentric distance range over which the associated burst
  is observed is closest to the Sun, and vice versa.

---------------------------------------------------------
Title: Determining ICME Magnetic Field Orientation with the ForeCAT
    In Situ Data Observer
Authors: Kay, Christina; Gopalswamy, N.; Reinard, A.; Opher, M.
2016usc..confE..20K    Altcode:
  CMEs drive the strongest space weather events at Earth and throughout
  the solar system. At Earth, the amount of southward magnetic field in a
  CME is a major component in determining the severity of an impact. We
  present results from ForeCAT (Forecasting a CME's Altered Trajectory,
  Kay et al. 2015), which predicts the deflection and rotation of
  CMEs based on magnetic forces determined by the background magnetic
  field. Using HMI magnetograms to reconstruct the background magnetic
  field and AIA images to constrain the early evolution of CMEs, we show
  that we can reproduce the deflection and rotation of CMEs observed
  in the corona. Using this CME location and orientation from ForeCAT
  results and a simple force-free flux rope model we show that we can
  reproduce the in situ magnetic profiles of Earth-impacting CMEs. We
  compare these results with the in situ profiles obtained assuming
  that no deflection or rotation occurs, and find that including these
  nonradial effects is essential for accurate space weather forecasting.

---------------------------------------------------------
Title: The Complex Solar Polarity Reversal during Cycle 24
Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.
2016usc..confE..37G    Altcode:
  The polarity reversal at solar poles is an important event
  with important implications for solar magnetism, the polarity
  of interplanetary coronal mass ejections, and even cosmic ray
  modulation. The poles often do not reverse simultaneously. During the
  several recent cycles, the north pole reversed first, followed by the
  south. During cycle 24, this trend has been broken in that the south
  pole reversed first. The polarity reversal is typically marked by
  the cessation of high-latitude eruptive activities such coronal mass
  ejections and prominence eruptions. Even though polar prominences
  started appearing as early as 2011, the reversal in the north was
  completed only by the end of 2015. On the other hand the south polar
  region behaved as in previous cycles and reversed over a shorter time
  scale, about a year before the reversal in the north. By combining
  prominence eruption detected automatically (Nobeyama Radioheliograph
  and SDO), the polar microwave brightness (Nobeyama Radioheliograph),
  and the magnetic butterfly diagram (SDO and NSO) we show that the
  complexity can be attributed to the emergence of active regions that
  violated the Hale polarity rule and Joy's law. The extended period of
  near-zero field in the north polar region should result in very weak
  and delayed sunspot activity in the northern hemisphere in cycle 25,
  the southern hemispheric activity should start early; the amplitude
  will depend on how the south polar fields will evolve in the declining
  phase of cycle (24).

---------------------------------------------------------
Title: Coronal magnetic field profiles from shock-CME standoff
    distances
Authors: Schmidt, J. M.; Cairns, Iver H.; Gopalswamy, N.; Yashiro, S.
2016JGRA..121.9299S    Altcode:
  Coronagraphs observe coronal mass ejections (CMEs) and driven
  shocks in white light images. From these observations the shock's
  speed and the shock's standoff distance from the CME's leading edge
  can be derived. Using these quantities, theoretical relationships
  between the shock's Alfvénic Mach number MA and standoff distance,
  and empirical radial profiles for the solar wind velocity and number
  density, the radial magnetic field profile upstream of the shock can
  be calculated. These profiles cannot be measured directly. We test the
  accuracy of this method for estimating the radial magnetic field profile
  upstream of the shock by simulating a sample CME that occurred on 29
  November 2013 using the three-dimensional (3-D) magnetohydrodynamic
  Block-Adaptive-Tree-Solarwind-Roe-Upwind-Scheme code, retrieving
  shock-CME standoff distances from the simulation, and comparing the
  estimated and simulated radial magnetic field profiles. We find good
  agreement between the two profiles (within ±30%) between 1.8 and 10
  R<SUB>⊙</SUB>. Our simulations confirm that a linear relationship
  exists between the standoff distance and the inverse compression ratio
  at the shock. We also find very good agreement between the empirical
  and simulated radial profiles of the number density and speed of the
  solar wind and inner corona.

---------------------------------------------------------
Title: On the reduced geoeffectiveness of solar cycle 24: A moderate
    storm perspective
Authors: Selvakumaran, R.; Veenadhari, B.; Akiyama, S.; Pandya, Megha;
   Gopalswamy, N.; Yashiro, S.; Kumar, Sandeep; Mäkelä, P.; Xie, H.
2016JGRA..121.8188S    Altcode:
  The moderate and intense geomagnetic storms are identified for
  the first 77 months of solar cycles 23 and 24. The solar sources
  responsible for the moderate geomagnetic storms are indentified during
  the same epoch for both the cycles. Solar cycle 24 has shown nearly 80%
  reduction in the occurrence of intense storms whereas it is only 40%
  in case of moderate storms when compared to previous cycle. The solar
  and interplanetary characteristics of the moderate storms driven by
  coronal mass ejection (CME) are compared for solar cycles 23 and 24
  in order to see reduction in geoeffectiveness has anything to do with
  the occurrence of moderate storm. Though there is reduction in the
  occurrence of moderate storms, the Dst distribution does not show much
  difference. Similarly, the solar source parameters like CME speed, mass,
  and width did not show any significant variation in the average values
  as well as the distribution. The correlation between VB<SUB>z</SUB>
  and Dst is determined, and it is found to be moderate with value of
  0.68 for cycle 23 and 0.61 for cycle 24. The magnetospheric energy
  flux parameter epsilon (ɛ) is estimated during the main phase of all
  moderate storms during solar cycles 23 and 24. The energy transfer
  decreased in solar cycle 24 when compared to cycle 23. These results
  are significantly different when all geomagnetic storms are taken into
  consideration for both the solar cycles.

---------------------------------------------------------
Title: Source Regions of the Type II Radio Burst Observed During a
    CME-CME Interaction on 2013 May 22
Authors: Mäkelä, P.; Gopalswamy, N.; Reiner, M. J.; Akiyama, S.;
   Krupar, V.
2016ApJ...827..141M    Altcode: 2016arXiv160606989G
  We report on our study of radio source regions during the type
  II radio burst on 2013 May 22 based on direction-finding analysis
  of the Wind/WAVES and STEREO/WAVES (SWAVES) radio observations at
  decameter-hectometric wavelengths. The type II emission showed an
  enhancement that coincided with the interaction of two coronal
  mass ejections (CMEs) launched in sequence along closely spaced
  trajectories. The triangulation of the SWAVES source directions
  posited the ecliptic projections of the radio sources near the line
  connecting the Sun and the STEREO-A spacecraft. The WAVES and SWAVES
  source directions revealed shifts in the latitude of the radio source,
  indicating that the spatial location of the dominant source of the
  type II emission varies during the CME-CME interaction. The WAVES
  source directions close to 1 MHz frequencies matched the location
  of the leading edge of the primary CME seen in the images of the
  LASCO/C3 coronagraph. This correspondence of spatial locations at
  both wavelengths confirms that the CME-CME interaction region is
  the source of the type II enhancement. Comparison of radio and
  white-light observations also showed that at lower frequencies
  scattering significantly affects radio wave propagation.

---------------------------------------------------------
Title: A small mission concept to the Sun-Earth Lagrangian L5 point
    for innovative solar, heliospheric and space weather science
Authors: Lavraud, B.; Liu, Y.; Segura, K.; He, J.; Qin, G.; Temmer,
   M.; Vial, J. -C.; Xiong, M.; Davies, J. A.; Rouillard, A. P.; Pinto,
   R.; Auchère, F.; Harrison, R. A.; Eyles, C.; Gan, W.; Lamy, P.;
   Xia, L.; Eastwood, J. P.; Kong, L.; Wang, J.; Wimmer-Schweingruber,
   R. F.; Zhang, S.; Zong, Q.; Soucek, J.; An, J.; Prech, L.; Zhang,
   A.; Rochus, P.; Bothmer, V.; Janvier, M.; Maksimovic, M.; Escoubet,
   C. P.; Kilpua, E. K. J.; Tappin, J.; Vainio, R.; Poedts, S.; Dunlop,
   M. W.; Savani, N.; Gopalswamy, N.; Bale, S. D.; Li, G.; Howard, T.;
   DeForest, C.; Webb, D.; Lugaz, N.; Fuselier, S. A.; Dalmasse, K.;
   Tallineau, J.; Vranken, D.; Fernández, J. G.
2016JASTP.146..171L    Altcode:
  We present a concept for a small mission to the Sun-Earth Lagrangian L5
  point for innovative solar, heliospheric and space weather science. The
  proposed INvestigation of Solar-Terrestrial Activity aNd Transients
  (INSTANT) mission is designed to identify how solar coronal magnetic
  fields drive eruptions, mass transport and particle acceleration that
  impact the Earth and the heliosphere. INSTANT is the first mission
  designed to (1) obtain measurements of coronal magnetic fields from
  space and (2) determine coronal mass ejection (CME) kinematics with
  unparalleled accuracy. Thanks to innovative instrumentation at a vantage
  point that provides the most suitable perspective view of the Sun-Earth
  system, INSTANT would uniquely track the whole chain of fundamental
  processes driving space weather at Earth. We present the science
  requirements, payload and mission profile that fulfill ambitious science
  objectives within small mission programmatic boundary conditions.

---------------------------------------------------------
Title: The Interaction between Coronal Mass Ejections (CMEs) and
    Coronal Holes (CHs) during the Solar Cycle 23 and its Geomagnetic
    Consequences
Authors: Mohamed, Amaal; Gopalswamy, Nat
2016cosp...41E1319M    Altcode:
  The interactions between the two large scale phenomena, coronal holes
  (CHs) and coronal mass ejections (CMEs) maybe considered as one of the
  most important relations that having a direct impact not only on space
  weather but also on the relevant plasma physics. Many observations have
  shown that throughout their propagation from the Sun to interplanetary
  space, CMEs interact with the heliospheric structures (e.g., other CMEs,
  Corotating interaction regions (CIRs), helmet streamers, and CHs). Such
  interactions could enhance the southward magnetic field component, which
  has important implications for geomagnetic storm generation. These
  interactions imply also a significant energy and momentum transfer
  between the interacting systems where magnetic reconnection is taking
  place. When CHs deflect CMEs away from or towards the Sun-Earth line,
  the geomagnetic response of the CME is highly affected. Gopalswamy et
  al. [2009] have addressed the deflection of CMEs due to the existence
  of CHs that are in close proximity to the eruption regions. They
  have shown that CHs can act as magnetic barriers that constrain CMEs
  propagation and can significantly affect their trajectories. Here,
  we study the interaction between coronal holes (CHs) and coronal mass
  ejections (CMEs) using a resultant force exerted by all coronal holes
  present on the disk and is defined as the coronal hole influence
  parameter (CHIP). The CHIP magnitude for each CH depends on the CH
  area, the distance between the CH centroid and the eruption region,
  and the average magnetic field within the CH at the photospheric
  level. The CHIP direction for each CH points from the CH centroid
  to the eruption region. We focus on Solar Cycle 23 CMEs originating
  from the disk center of the Sun (central meridian distance &lt; 15
  °). We present an extensive statistical study via compiling data
  sets of observations of CMEs and their interplanetary counterparts;
  known as interplanetary CMEs (ICMEs). There are 2 subsets of ICMEs:
  magnetic cloud (MC) and non-magnetic cloud (non-MC) ICMEs. MCs are
  identified by a smooth change of the magnetic field as measured with
  spacecraft at 1 AU, using ACE and Wind spacecraft. It is found that the
  maximum phase has the largest CHIP value (2.9 G) for non-MCs. The CHIP
  is the largest (5.8 G) for driverless (DL) shocks, which are shocks at
  1 AU with no discernible MC or non-MC. These results suggest that the
  behavior of non-MCs is similar to that of the DL shocks and different
  from that of MCs. In other words, the CHs may deflect the CMEs away
  from the Sun-Earth line and force them to behave like limb CMEs with
  DL shocks. This finding supports the idea that all CMEs may be flux
  ropes if viewed from an appropriate vantage point.

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.721G    Altcode:
  Discussion

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.728G    Altcode:
  Discussion

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.729G    Altcode:
  Discussion

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.714G    Altcode:
  Discussion

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.723G    Altcode:
  Discussion

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.727G    Altcode:
  Discussion

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.726G    Altcode:
  Discussion

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.716G    Altcode:
  Discussion

---------------------------------------------------------
Title: The differences between CME-rich and CME-poor Active Regions
Authors: Akiyama, Sachiko; Yashiro, Seiji; Gopalswamy, Nat; Mäkelä,
   Pertti
2016shin.confE.159A    Altcode:
  We studied the association of coronal mass ejections (CMEs) with large
  X-ray flares occurring in flare-productive active regions (ARs). The
  flare-productive ARs are defined as those which produce more than five
  M1-class flares during their passage from the east to west limb. A
  total of 1236 large X-ray flares were produced from 132 such ARs in
  the period 1996 to 2015. We examined the CME association rate (RCME)
  for each AR as an index of AR"s CME-productivity using by LASCO/SOHO
  and SECCHI/STEREO. It is reasonable to expect that average RCME of the
  flare-productive ARs is 50%, because about half of M1 class flares
  have CME association. However, out of the 132 ARs, 20 were CME-rich
  (RCME &gt; 80%) and 21 were CME-poor (RCME &lt; 20%). AR size and
  magnetic potential energy do not seem to differ significantly between
  CME-rich and CME-poor ARs. We did find a significant difference in the
  recurrence time of flares in CME-rich ARs (average = 21.6 h) and hose
  in CME-poor them (14.7 h). We discuss additional differences between
  the two types of ARs.

---------------------------------------------------------
Title: Interaction between Coronal Mass Ejections: Limited Spatial
    Extent Revealed by SOHO Observations
Authors: Gopalswamy, Nat; Reiner, Mike J.; Makela, Pertti; Yashiro,
   Seiji
2016cosp...41E.711G    Altcode:
  A spectacular CME interaction event was observed on 2013 May 22 by
  the Large Angle and Spectrometric Coronagraph (LASCO) on board the
  Solar and Heliospheric Observatory (SOHO) mission as confirmed by
  the radio signature detected by the Radio and Plasma Wave experiment
  (WAVES) on board the Wind spacecraft. The interaction event was also
  associated with an intense solar energetic particle event, typical of
  such events in solar cycles 23 and 24. Detailed height-time plots of
  the interacting CMEs at various position angles revealed a surprising
  result: only a limited spatial extent of the primary CME was affected
  by the interaction. The speed of the primary CME showed a sharp
  decline in the position angle range where it interacted with the
  preceding CME. At these position angles, the speed of the preceding
  CME increased. At position angles away from the interaction region,
  the speed of the primary CME remained roughly the same except for the
  usual drag deceleration. This result has important implications to
  theories on CME collision: treating the interacting CMEs to be rigid
  bodies and using the whole mass of the CMEs may not be correct.

---------------------------------------------------------
Title: Energy dependence of SEP electron and proton onset times
Authors: Xie, H.; Mäkelä, P.; Gopalswamy, N.; St. Cyr, O. C.
2016JGRA..121.6168X    Altcode: 2016arXiv160908171X
  We study the large solar energetic particle (SEP) events that were
  detected by GOES in the &gt;10 MeV energy channel during December 2006
  to March 2014. We derive and compare solar particle release (SPR)
  times for the 0.25-10.4 MeV electrons and 10-100 MeV protons for
  the 28 SEP events. In the study, the electron SPR times are derived
  with the time-shifting analysis (TSA) and the proton SPR times are
  derived using both the TSA and the velocity dispersion analysis
  (VDA). Electron anisotropies are computed to evaluate the amount of
  scattering for the events under study. Our main results include (1)
  near-relativistic electrons and high-energy protons are released at
  the same time within 8 min for most (16 of 23) SEP events. (2)There
  exists a good correlation between electron and proton acceleration,
  peak intensity, and intensity time profiles. (3) The TSA SPR times
  for 90.5 MeV and 57.4 MeV protons have maximum errors of 6 min and
  10 min compared to the proton VDA release times, respectively, while
  the maximum error for 15.4 MeV protons can reach to 32 min. (4) For
  7 low-intensity events of the 23, large delays occurred for 6.5 MeV
  electrons and 90.5 MeV protons relative to 0.5 MeV electrons. Whether
  these delays are due to times needed for the evolving shock to be
  strengthened or due to particle transport effects remains unsolved.

---------------------------------------------------------
Title: Unusual Polar Activity of the Sun in the Northern Hemisphere
    and Its Implications for Solar Cycle 25
Authors: Gopalswamy, Nat; Masuda, Satoshi; Yashiro, Seiji; Akiyama,
   Sachiko; Shibasaki, Kiyoto
2016cosp...41E.712G    Altcode:
  Polar field strength in one solar cycle is known to indicate the
  strength (e.g., Sunspot number) and phase of the next cycle. In
  particular the polar field strength (or its proxies such as the
  polar coronal hole area and microwave polar brightness) during the
  minimum phase of a given cycle seem to be well correlated with the
  maximum sunspot number of the next cycle. Polar prominence eruptions
  and coronal mass ejections have also been found to be indicators
  of low polar field; their cessation signals the time of polarity
  reversal. While these indicators are present in the current cycle,
  significant differences are found regarding the phase lag between the
  two hemispheres and the duration of polar eruptions. We use data from
  the Nobeyama Radioheliograph, the Solar Dynamics Observatory, SOLIS,
  and Wilcox Solar Observatory to highlight these differences. We find
  that the north polar region of the Sun has near-zero field strength for
  more than three years. This is unusually long and caused by surges of
  both polarities heading toward the north pole that prevent the buildup
  of the polar field. This seems to be due to anti-Hale active regions
  that appeared around the 2012 peak sunspot activity in the northern
  hemisphere. The unusual condition is consistent with (i) the continued
  high-latitude prominence eruption, (ii) the extended period of high
  tilt angle of the heliospheric current sheet, (iii) the weak microwave
  polar brightness, and (iv) the lack of north polar coronal hole. On
  the other hand, the south polar field has started building up and the
  coronal hole has appeared in early 2015 because of large active regions
  of the correct tilt in the southern hemisphere during the 2014 peak of
  sunspot activity. The extended period of near-zero field in the north
  polar region should result in very weak and delayed sunspot activity
  in the northern hemisphere in cycle 25. On the other hand the south
  polar field has already increased significantly, suggesting that the
  activity in the southern hemisphere should start early; the amplitude
  will depend on how the south polar fields will evolve in the declining
  phase of cycle (24).

---------------------------------------------------------
Title: Deflection and Rotation of CMEs from AR 11158
Authors: Kay, Christina Danielle; Gopalswamy, N.; Xie, H.; Yashiro, S.
2016shin.confE..41K    Altcode:
  Between the 13th and 16th of February 2011 a series of CMEs erupted
  from multiple polarity inversion lines within AR 11158. For seven of
  these CMEs we use the Graduated Cylindrical Shell (GCS) flux rope model
  to determine the CME trajectory using both STEREO EUV and coronagraph
  images. We then use ForeCAT, a model for nonradial CME dynamics driven
  by magnetic forces, to simulate the deflection and rotation of the
  seven CMEs. We find good agreement between the ForeCAT results and the
  reconstructed CME positions and orientations. The CME deflections range
  in magnitude between 10 and 30 degrees. All CMEs deflect to the north
  but we find variation in direction of the longitudinal deflection. The
  rotations range between 5 degrees and 50 degrees with both clockwise and
  counterclockwise rotation occurring. Four of the CMEs begin with initial
  positions within 2 degrees of one another. These four CMEs all deflect
  primarily northward, with some minor eastward deflection, and rotate
  counterclockwise. Their final positions and orientations, however,
  respectively differ by 20 degrees and 30 degrees. This variation in
  deflection and rotation results from differences in the CME expansion
  and radial propagation close to the Sun, as well as the CME mass.

---------------------------------------------------------
Title: Kinematics of slow and fast CMEs in soar cycle 23 and 24
Authors: Banerjee, Dipankar; Gopalswamy, Nat; Pant, Vaibhav
2016cosp...41E.140B    Altcode:
  CMEs are episodic expulsion of plasma and magnetic fields from Sun into
  heliosphere. CMEs can be classified, based on their speeds, as slow CMEs
  and fast CMEs. We find that slow CMEs and fast CMEs behave differently
  in two cycles. While fast CMEs seem to follow the sunspot variations,
  slow CMEs have much flatter distribution. Thus the distribution of
  total CMEs is affected by slow CME populations. We find double peak
  behaviour in fast CMEs, since they follow the sunspot distribution, in
  both the cycles without any significant delay from sunspot variation. It
  suggests that most of the fast CMEs originates from active regions
  associated with sunspots. We also find double peak behaviour in slow
  CMEs in cycle 24 but not in cycle 23. In addition to this the number of
  slow CMEs are far more than in cycle 23. These findings point towards
  the fact that in cycle 24 slow CMEs to some extent are associated with
  sunspots and due to weak heliospheric field they could somehow escape
  easily thus giving double peak behaviour and larger distribution in
  cycle 24. Apart from this we also find that slow and fast CMEs follow
  different power laws. This may shed light on their origin as well.

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.717G    Altcode:
  Discussion

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.715G    Altcode:
  Discussion

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.720G    Altcode:
  Discussion

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.722G    Altcode:
  Discussion

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.719G    Altcode:
  Discussion

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.730G    Altcode:
  Discussion

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.718G    Altcode:
  Discussion

---------------------------------------------------------
Title: Smaller Forbush Decreases in Solar Cycle 24: Effect of the
    Weak CME Field Strength?
Authors: Thakur, Neeharika; Gopalswamy, N.; Yashiro, S.; Akiyama,
   S.; Xie, H.; Mäkelä, P.
2016shin.confE.172T    Altcode:
  A Forbush decrease (FD) is a sudden depression in the intensity
  of galactic cosmic ray (GCR) background, followed by a gradual
  recovery. One of the major causes of FDs is the presence of magnetic
  structures such as magnetic clouds (MCs) or corotating interaction
  regions (CIRs) that have enhanced magnetic field, which can scatter
  particles away reducing the observed GCR intensity. Recent work
  (Gopalswamy et al. 2014, GRL 41, 2673) suggests that coronal mass
  ejections (CMEs) are expanding anomalously in solar cycle 24 due to the
  reduced total pressure in the ambient medium. One of the consequences
  of the anomalous expansion is the reduced magnetic content of MCs,
  so we expect subdued FDs in cycle 24. In this paper, we present
  preliminary results from a survey of FDs during MC events in cycle
  24 in comparison with those in cycle 23. We find that only 17% FDs in
  cycle 24 had an amplitude &gt;3%, as compared to 31% in cycle 23. This
  result is consistent with the difference in the maximum magnetic field
  intensities (Bmax) of MCs in the two cycles: only 10% of MCs in cycle
  24 have Bmax&gt;20nT, compared to 22% in cycle 23, confirming that MCs
  of cycle 24 have weaker magnetic field content. Therefore, we suggest
  that weaker magnetic field intensity in the magnetic clouds of cycle
  24 has led to FDs with smaller amplitudes.

---------------------------------------------------------
Title: The 2012 July 23 Backside Event: An Extreme Energetic
    Particle Event?
Authors: Gopalswamy, Nat; Makela, Pertti; Yashiro, Seiji
2016shin.confE.173G    Altcode:
  The backside coronal mass ejection (CME) of 2012 July 23 has received
  considerable attention because many of its characteristics place
  it among the historical extreme solar events. For example, the
  shock transit time from Sun to 1 au was 18.5 hours, similar to the
  two 2003 Halloween events on October 28 and 29. The CME speed well
  exceeded 2000 km/s as observed from three views: the STEREO-Ahead,
  STEREO-Behind, and SOHO. The CME erupted from S17W141 and was heading
  roughly towards STEREO-A. The solar energetic particle (SEP) event
  had a peak value of 5000 pfu in the &gt;10 MeV channel. The energetic
  storm particle (ESP) event was an order of magnitude larger, placing
  it among the most intense events in the space era. In this paper, we
  examine whether the CME in this event could have accelerated particles
  to GeV energies. The STEREO particle detectors do not have energy
  channels higher than 100 MeV, so we determine the SEP spectrum in
  the range 10-100 MeV and compare it with that of other ground level
  enhancement (GLE) events. We find that the spectrum of the 2012 July
  23 event is very hard (power law index 1.66), harder than that of all
  GLE events in cycles 23 and 24. Only the most intense GLE of cycle 23
  (2005 January 20), had a 10-100 MeV spectral index of 1.66. The two
  GLE events of cycle 24 had spectral indices of 2.14 (2012 May 17) and
  2.18 (2014 January 6). Thus we conclude that the 2012 July 23 event is
  likely to be an extreme event in terms of the energetic particles it
  accelerated. We also discuss additional characteristics of the event,
  which support this conclusion.

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.724G    Altcode:
  Discussion

---------------------------------------------------------
Title: Discussion
Authors: Gopalswamy, Nat
2016cosp...41E.725G    Altcode:
  Discussion

---------------------------------------------------------
Title: Investigation on source locations of interplanetary type II
    radio bursts using radio direction finding
Authors: Makela, Pertti; Gopalswamy, Nat; Akiyama, Sachiko
2016shin.confE.167M    Altcode:
  Source locations of interplanetary (IP) type II radio bursts can be
  studied by comparing radio source directions obtained using direction
  finding (DF) techniques with the white-light images of the associated
  coronal mass ejections (CMEs). Previously this method has been used
  to confirm that a CME-CME interaction event is the source of the
  concurrently observed type II enhancement. These IP type II enhancements
  are well suited for DF studies, because the signal-to-noise ratio of
  the radio emission is sufficiently high. Regular IP type II bursts
  are often fainter, especially so during solar cycle 24, which is
  characterized by a lower solar activity level and a smaller number of
  intense solar eruptions compared to solar cycle 23. In addition, it
  is known that radio wave scattering affects the DF source directions
  at lower frequencies. We report on our investigation on locating the
  radio source of regular IP type II radio bursts by comparing the DF
  source directions with the white-light images of the associated CMEs.

---------------------------------------------------------
Title: Detection of Nonthermal Radio Emission from a Polar coronal
    mass ejection
Authors: Gopalswamy, Nat; Reiner, Mike J.; Makela, Pertti; Yashiro,
   Seiji; Akiyama, Sachiko
2016cosp...41E.713G    Altcode:
  High-latitude coronal mass ejections from the polar crown region are
  generally of low energy and hence thought to be not responsible for
  driving shocks. However, the eruption of such CMEs are associated with
  weak post eruption arcades suggesting that particle acceleration does
  happen in the reconnection region beneath the erupting filaments. An
  unusually fast CME erupted from the southern polar crown on 1999 June
  14 observed by the Large Angle and Spectrometric Coronagraph (LASCO)
  on board the Solar and Heliospheric Observatory (SOHO) mission. The
  post eruption arcade was observed by the Soft X-ray Telescope on board
  the Yohkoh mission and the Extreme-ultraviolet imaging Telescope
  (EIT) on board SOHO. A diffuse radio emission was observed below 1
  MHz by the Radio and Plasma Wave experiment (WAVES) on board the Wind
  spacecraft. The good temporal association between the radio burst and
  the CME suggests that the CME must be the source of energy for the
  radio emission. The drift rate of the radio burst was much smaller
  than that of a typical interplanetary type II burst. We suggest that
  the radio burst is produced by a flank of the CME-driven shock passing
  through a streamer located close to the east limb of the Sun. Such
  an interaction is likely to have caused the slow drift of the burst
  because the shock flank passes roughly parallel to the solar surface
  in the flank region. The enhanced density in the streamer makes the
  local Alfven speed lower, making the shock sufficiently strong to
  accelerate a few keV electrons that lead to the radio emission. The
  diffuse feature also contains a series of spikes, which suggest
  possible escape of nonthermal electrons along open field lines. We
  use the radio direction finding to confirm the results. This result
  has important implications for particle acceleration by shock flanks,
  where the geometry is expected to be quasi-perpendicular.

---------------------------------------------------------
Title: Low-Frequency Radio Bursts and Space Weather
Authors: Gopalswamy, Nat
2016arXiv160502218G    Altcode:
  Low-frequency radio phenomena are due to the presence of nonthermal
  electrons in the interplanetary (IP) medium. Understanding these
  phenomena is important in characterizing the space environment near
  Earth and other destinations in the solar system. Substantial progress
  has been made in the past two decades, because of the continuous and
  uniform data sets available from space-based radio and white-light
  instrumentation. This paper highlights some recent results obtained
  on IP radio phenomena. In particular, the source of type IV radio
  bursts, the behavior of type III storms, shock propagation in the
  IP medium, and the solar-cycle variation of type II radio bursts are
  considered. All these phenomena are closely related to solar eruptions
  and active region evolution. The results presented were obtained by
  combining data from the Wind and SOHO missions.

---------------------------------------------------------
Title: Solar Activity Studies using Microwave Imaging Observations
Authors: Gopalswamy, Nat
2016arXiv160502221G    Altcode:
  We report on the status of solar cycle 24 based on polar prominence
  eruptions (PEs) and microwave brightness enhancement (MBE) information
  obtained by the Nobeyama radioheliograph. The north polar region of
  the Sun had near-zero field strength for more than three years (2012
  to 2015) and ended only in September 2015 as indicated by the presence
  of polar PEs and the lack of MBE. The zero-polar-field condition in
  the south started only around 2013, but it ended by June 2014. Thus
  the asymmetry in the times of polarity reversal switched between cycle
  23 and 24. The polar MBE is a good proxy for the polar magnetic field
  strength as indicated by the high degree of correlation between the
  two. The cross-correlation between the high- and low-latitude MBEs is
  significant for a lag of ~5.5 to 7.3 years, suggesting that the polar
  field of one cycle indicates the sunspot number of the next cycle in
  agreement with the Babcock-Leighton mechanism of solar cycles. The
  extended period of near-zero field in the north-polar region should
  result in a weak and delayed sunspot activity in the northern hemisphere
  in cycle 25.

---------------------------------------------------------
Title: On the Directivity of Low-Frequency Type IV Radio Bursts
Authors: Gopalswamy, Nat; Akiyama, Sachiko; Mäkelä, Pertti; Yashiro,
   Seiji; Cairns, Iver H.
2016arXiv160502223G    Altcode:
  An intense type IV radio burst was observed by the STEREO Behind
  (STB) spacecraft located about 144 degres behind Earth. The burst was
  associated with a large solar eruption that occurred on the backside
  of the Sun (N05E151) close to the disk center in the STB view. The
  eruption was also observed by the STEREO Ahead (STA) spacecraft
  (located at 149 degrees ahead of Earth) as an eruption close to the
  west limb (N05W60) in that view. The type IV burst was complete in STB
  observations in that the envelope reached the lowest frequency and then
  receded to higher frequencies. The burst was partial viewed from STA,
  revealing only the edge coming down to the lowest frequency. The type
  IV burst was not observed at all near Earth because the source was
  61 degrees behind the east limb. The eruption was associated with a
  low-frequency type II burst observed in all three views, although it
  was not very intense. Solar energetic particles were also observed at
  both STEREOs and at SOHO, suggesting that the shock was much extended,
  consistent with the very high speed of the CME (about 2048 km/s). These
  observations suggest that the type IV emission is directed along a
  narrow cone above the flare site. We confirm this result statistically
  using the type IV bursts of solar cycle 23.

---------------------------------------------------------
Title: Minifilament Eruptions that Drive Coronal Jets in a Solar
    Active Region
Authors: Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David;
   Panesar, Navdeep; Akiyama, Sachiko; Yashiro, Seiji; Gopalswamy, Nat
2016SPD....47.0334S    Altcode:
  Solar coronal jets are common in both coronal holes and in active
  regions. Recently, Sterling et al. (2015), using data from Hinode/XRT
  and SDO/AIA, found that coronal jets originating in polar coronal holes
  result from the eruption of small-scale filaments (minifilaments). The
  jet bright point (JBP) seen in X-rays and hotter EUV channels off to one
  side of the base of the jet's spire develops at the location where the
  minifilament erupts, consistent with the JBPs being miniature versions
  of typical solar flares that occur in the wake of large-scale filament
  eruptions. Here we consider whether active region coronal jets also
  result from the same minifilament-eruption mechanism, or whether they
  instead result from a different mechanism, such as the hitherto popular
  “emerging flux” model for jets. We present observations of an on-disk
  active region that produced numerous jets on 2012 June 30, using data
  from SDO/AIA and HMI, and from GOES/SXI. We find that several of these
  active region jets also originate with eruptions of miniature filaments
  (size scale ~20”) emanating from small-scale magnetic neutral lines
  of the region. This demonstrates that active region coronal jets are
  indeed frequently driven by minifilament eruptions. Other jets from the
  active region were also consistent with their drivers being minifilament
  eruptions, but we could not confirm this because the onsets of those
  jets were hidden from our view. This work was supported by funding
  from NASA/LWS, NASA/HGI, and Hinode.

---------------------------------------------------------
Title: Unusual Polar Conditions in Solar Cycle 24 and Their
    Implications for Cycle 25
Authors: Gopalswamy, Nat; Yashiro, Seiji; Akiyama, Sachiko
2016ApJ...823L..15G    Altcode: 2016arXiv160502217G
  We report on the prolonged solar-maximum conditions until late 2015
  at the north-polar region of the Sun indicated by the occurrence of
  high-latitude prominence eruptions (PEs) and microwave brightness
  temperature close to the quiet-Sun level. These two aspects of solar
  activity indicate that the polarity reversal was completed by mid-2014
  in the south and late 2015 in the north. The microwave brightness in
  the south-polar region has increased to a level exceeding the level of
  the Cycle 23/24 minimum, but just started to increase in the north. The
  north-south asymmetry in the polarity reversal has switched from that
  in Cycle 23. These observations lead us to the hypothesis that the
  onset of Cycle 25 in the northern hemisphere is likely to be delayed
  with respect to that in the southern hemisphere. We find that the
  unusual condition in the north is a direct consequence of the arrival
  of poleward surges of opposite polarity from the active region belt. We
  also find that multiple rush-to-the-pole episodes were indicated by the
  PE locations that lined up at the boundary between opposite-polarity
  surges. The high-latitude PEs occurred in the boundary between the
  incumbent polar flux and the insurgent flux of opposite polarity.

---------------------------------------------------------
Title: A Study of the 2012 January 19 Complex Type II Radio Burst
    Using Wind, SOHO, and STEREO Observations
Authors: Teklu, T. B.; Gholap, A. V.; Gopalswamy, N.; Yashiro, S.;
   Mäkelä, P.; Akiyama, S.; Thakur, N.; Xie, H.
2016arXiv160509644T    Altcode:
  We report on a case study of the complex type II radio burst of
  2012 January 19 and its association with a white light coronal mass
  ejection (CME). The complexity can be described as the appearance of an
  additional type II burst component and strong intensity variation. The
  dynamic spectrum shows a pair of type II bursts with fundamental
  harmonic structures, one confined to decameter-hectometric (DH)
  wavelengths and the other extending to kilometric (km) wavelengths. By
  comparing the speeds obtained from white-light images with that speed
  of the shock inferred from the drift rate, we show that the source of
  the short-lived DH component is near the nose.

---------------------------------------------------------
Title: Minifilament Eruptions that Drive Coronal Jets in a Solar
    Active Region
Authors: Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David A.;
   Panesar, Navdeep K.; Akiyama, Sachiko; Yashiro, Seiji; Gopalswamy, Nat
2016ApJ...821..100S    Altcode:
  We present observations of eruptive events in an active region adjacent
  to an on-disk coronal hole on 2012 June 30, primarily using data from
  the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA),
  SDO/Helioseismic and Magnetic Imager (HMI), and STEREO-B. One eruption
  is of a large-scale (∼100″) filament that is typical of other
  eruptions, showing slow-rise onset followed by a faster-rise motion
  starting as flare emissions begin. It also shows an “EUV crinkle”
  emission pattern, resulting from magnetic reconnections between
  the exploding filament-carrying field and surrounding field. Many
  EUV jets, some of which are surges, sprays and/or X-ray jets, also
  occur in localized areas of the active region. We examine in detail
  two relatively energetic ones, accompanied by GOES M1 and C1 flares,
  and a weaker one without a GOES signature. All three jets resulted
  from small-scale (∼20″) filament eruptions consistent with a slow
  rise followed by a fast rise occurring with flare-like jet-bright-point
  brightenings. The two more-energetic jets showed crinkle patters, but
  the third jet did not, perhaps due to its weakness. Thus all three jets
  were consistent with formation via erupting minifilaments, analogous
  to large-scale filament eruptions and to X-ray jets in polar coronal
  holes. Several other energetic jets occurred in a nearby portion of
  the active region; while their behavior was also consistent with their
  source being minifilament eruptions, we could not confirm this because
  their onsets were hidden from our view. Magnetic flux cancelation
  and emergence are candidates for having triggered the minifilament
  eruptions.

---------------------------------------------------------
Title: CME flux rope and shock identifications and locations:
    Comparison of white light data, Graduated Cylindrical Shell model,
    and MHD simulations
Authors: Schmidt, J. M.; Cairns, Iver H.; Xie, Hong; St. Cyr, O. C.;
   Gopalswamy, N.
2016JGRA..121.1886S    Altcode:
  Coronal mass ejections (CMEs) are major transient phenomena in the
  solar corona that are observed with ground-based and spacecraft-based
  coronagraphs in white light or with in situ measurements by
  spacecraft. CMEs transport mass and momentum and often drive shocks. In
  order to derive the CME and shock trajectories with high precision,
  we apply the graduated cylindrical shell (GCS) model to fit a flux
  rope to the CME directed toward STEREO A after about 19:00 UT on 29
  November 2013 and check the quality of the heliocentric distance-time
  evaluations by carrying out a three-dimensional magnetohydrodynamic
  (MHD) simulation of the same CME with the Block Adaptive Tree Solar-Wind
  Roe Upwind Scheme (BATS-R-US) code. Heliocentric distances of the
  CME and shock leading edges are determined from the simulated white
  light images and magnetic field strength data. We find very good
  agreement between the predicted and observed heliocentric distances,
  showing that the GCS model and the BATS-R-US simulation approach
  work very well and are consistent. In order to assess the validity of
  CME and shock identification criteria in coronagraph images, we also
  compute synthetic white light images of the CME and shock. We find
  that the outer edge of a cloud-like illuminated area in the observed
  and predicted images in fact coincides with the leading edge of the
  CME flux rope and that the outer edge of a faint illuminated band in
  front of the CME leading edge coincides with the CME-driven shock front.

---------------------------------------------------------
Title: Two Exceptions in the Large SEP Events of Solar Cycles 23
    and 24
Authors: Thakur, N.; Gopalswamy, N.; Mäkelä, P.; Akiyama, S.;
   Yashiro, S.; Xie, H.
2016SoPh..291..513T    Altcode: 2016SoPh..tmp...21T
  We discuss our findings from a survey of all large solar energetic
  particle (SEP) events of Solar Cycles 23 and 24, i.e. the SEP events
  where the intensity of &gt; 10 MeV protons observed by GOES was &gt; 10
  pfu. In our previous work (Gopalswamy et al. in Geophys. Res. Lett. 41,
  2673, 2014) we suggested that ground level enhancements (GLEs) in Cycles
  23 and 24 also produce an intensity increase in the GOES &gt; 700 MeV
  proton channel. Our survey, now extended to include all large SEP events
  of Cycle 23, confirms this to be true for all but two events: i) the
  GLE of 6 May 1998 (GLE57) for which GOES did not observe enhancement
  in &gt; 700 MeV protons intensities and ii) a high-energy SEP event
  of 8 November 2000, for which GOES observed &gt; 700 MeV protons
  but no GLE was recorded. Here we discuss these two exceptions. We
  compare GLE57 with other small GLEs, and the 8 November 2000 SEP event
  with those that showed similar intensity increases in the GOES &gt;
  700 MeV protons but produced GLEs. We find that, because GOES &gt;
  700 MeV proton intensity enhancements are typically small for small
  GLEs, they are difficult to discern near solar minima due to higher
  background. Our results also support that GLEs are generally observed
  when shocks of the associated coronal mass ejections (CMEs) form at
  heights 1.2 - 1.93 solar radii [R<SUB>⊙</SUB>] and when the solar
  particle release occurs between 2 - 6 R<SUB>⊙</SUB>. Our secondary
  findings support the view that the nose region of the CME-shock may
  be accelerating the first-arriving GLE particles and the observation
  of a GLE is also dependent on the latitudinal connectivity of the
  observer to the CME-shock nose. We conclude that the GOES &gt; 700 MeV
  proton channel can be used as an indicator of GLEs excluding some rare
  exceptions, such as those discussed here.

---------------------------------------------------------
Title: Special issue "International CAWSES-II Symposium"
Authors: Yamamoto, Mamoru; Shiokawa, Kazuo; Nakamura, Takuji;
   Gopalswamy, Nat
2016EP&S...68...26Y    Altcode:
  This special issue gathered papers from the International
  CAWSES-II Symposium (November 18-22, 2013 at Nagoya University,
  Japan). Climate and Weather of the Sun-Earth System II (CAWSES-II)
  is an international scientific program sponsored by Scientific
  Committee on Solar-Terrestrial Physics (SCOSTEP) that continued from
  2009 to 2013. The program was established with the aim of significantly
  enhancing our understanding of the space environment and its impacts on
  life and society. The International CAWSES-II Symposium was successful
  with 388 presentations; and from that, 38 papers were published in
  this special issue. In this preface, we briefly discuss the contents
  of the special issue as well as the CAWSES-II review papers published
  in Progress in Earth and Planetary Science (PEPS) in 2014-2015.

---------------------------------------------------------
Title: Current Polar Activity of the Sun and Its implications for
    Solar Cycle 25
Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.
2015AGUFMSH23A2424G    Altcode:
  Polar activity of one solar cycle is known to indicate certain
  characteristics of the subsequent cycle in terms of strength (e.g.,
  Sunspot number) and phase. In particular the polar field strength
  (or its proxies such as the microwave polar brightness) during the
  minimum phase of seem to be well correlated with the maximum sunspot
  number of the next cycle. Polar prominence eruptions and coronal
  mass ejections have also been found to be important indicators of the
  time of polarity reversal. While these indicators are present in the
  current cycle, significant differences are found regarding the phase
  lag between the two hemispheres and the duration of polar eruptions. We
  use prominence eruption data from the Nobeyama Radioheliograph and the
  Solar Dynamics Observatory to highlight these differences. We also use
  the polar microwave brightness variation and discuss the implications
  to solar cycle 25.

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Title: Energy Dependence of SEP Electron and Proton Onset Times
Authors: Makela, P. A.; Xie, H.; Gopalswamy, N.; St Cyr, O. C.
2015AGUFMSH33B2468M    Altcode:
  We study the large solar energetic particle (SEP) events that were
  detected by GOES in the &gt; 10 MeV energy channel during December 2006
  to March 2014. Using multi-spacecraft observations from STEREO A, B and
  SOHO, we are able to determine accurately the solar particle release
  (SPR) time of SEP electrons and protons. We first compute connection
  angles (CA) between the solar events and magnetic foot-points connecting
  to each spacecraft. By choosing the smallest CA, we derive the electron
  and proton SPRs using electron fluxes from the SOHO Electron Proton
  and Helium Instrument (EPHIN), proton fluxes from the SOHO Energetic
  and Relativistic Nuclei and Electron instrument (ERNE), and from the
  High Energy Telescope (HET) on STEREO. It is found that: 1) the 0.25
  MeV-0.7 MeV electron SPRs are ~10 min earlier than 2.64 MeV - 10.4 Mev
  electron SPRs; 2) the proton SPRs inferred from high-energy channels
  (&gt; 50 MeV) are similar to electron SPRs; 3) the proton SPRs inferred
  from lower energy channel (10 - 16.9 MeV) can be either ~ 7 min earlier
  than or delayed from the electron SPRs for tens of minutes to hours,
  especially for SEPs with large pre-event background flux levels. In
  this study, we evaluated the effects of large scattering and high
  background levels on SPRs and made suggested corrections for the
  background effect on SPR times. We also find that for some large SEP
  events, the observed EPHIN electron and ERNE proton intensity profiles
  show a double-peak feature. The onset of the first peak corresponds
  well to the associated Type III and metric Type II onset and tends to
  be nearly scattering-free.

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Title: A Comparative Study of Confined and Eruptive Solar Flares
    using Microwave Observations
Authors: Yashiro, S.; Akiyama, S.; Masuda, S.; Shimojo, M.; Asai,
   A.; Imada, S.; Gopalswamy, N.
2015AGUFMSH43B2447Y    Altcode:
  It is well known that about 10% X-class solar flares are not associated
  with coronal mass ejections (CMEs). These flares are referred to
  as confined flares, which are not associated with mass or energetic
  particles leaving the Sun. However, electrons are accelerated to MeV
  energies as indicated by the presence of microwave emission with a
  turnover frequency of ~15 GHz (Gopalswamy et al. 2009, IAU Symposium
  257, p. 283). In this paper, we extend the study of confined flares to
  lower soft X-ray flare sizes (M and above) that occurred in the time
  window of the Nobeyama Radioheliograph (NoRH). We also make use of the
  microwave spectral information from the Nobeyama Radio Polarimeters
  (NoRP). During 1996 - 2014, NoRH and NoRP observed 663 flares with
  size M1.0 or larger. Using the CME observations made by SOHO/LASCO
  and STEREO/SECCHI, we found 215 flares with definite CME association
  (eruptive flares) and 202 flares that definitely lacked CMEs (confined
  flares). The remaining 146 flares whose CME association is unclear are
  excluded from the analysis. We examined the peak brightness temperature
  and the spatial size obtained by NoRH. Although there is a large
  overlap between the two populations in these properties, we found
  that microwave sources with the largest spatial extent and highest
  brightness temperature are associated with eruptive flares. Spectral
  analysis using NoRP data showed a tendency that more confined flares
  had higher turnover frequency (≥17 GHz). We also compare the NoRH
  images with the photospheric magnetograms to understand the difference
  in the magnetic structure of the two types of flare sources.

---------------------------------------------------------
Title: CMEs during the Two Activity Peaks in Cycle 24 and their
    Space Weather Consequences
Authors: Gopalswamy, N.; Makela, P.; Akiyama, S.; Yashiro, S.;
   Thakur, N.
2015SunGe..10..111G    Altcode: 2015arXiv150904216G
  We report on a comparison between space weather events that occurred
  around the two peaks in the sunspot number (SSN) during solar cycle
  24. The two SSN peaks occurred in the years 2012 and 2014. Even
  though SSN was larger during the second peak, we find that there were
  more space weather events during the first peak. The space weather
  events we considered are large solar energetic particle (SEP) events
  and major geomagnetic storms associated with coronal mass ejections
  (CMEs). We also considered interplanetary type II radio bursts, which
  are indicative of energetic CMEs driving shocks. When we compared the
  CME properties between the two SSN peaks, we find that more energetic
  CMEs occurred during the 2012 peak. In particular, we find that CMEs
  accompanying IP type II bursts had an average speed of 1543 km/s
  during the 2012 peak compared to 1201 km/s during the 2014 peak. This
  result is consistent with the reduction in the average speed of the
  general population of CMEs during the second peak. All SEP events
  were associated with the interplanetary type II bursts, which are
  better than halo CMEs as indicators of space weather. The comparison
  between the two peaks also revealed the discordant behavior between
  the CME rate and SSN was more pronounced during the second peak. None
  of the 14 disk-center halo CMEs was associated with a major storm in
  2014. The lone major storm in 2014 was due to the intensification of
  the (southward) magnetic field in the associated magnetic cloud by a
  shock that caught up and propagated into the magnetic cloud.

---------------------------------------------------------
Title: Short-term variability of the Sun-Earth system: an overview
    of progress made during the CAWSES-II period
Authors: Gopalswamy, Nat; Tsurutani, Bruce; Yan, Yihua
2015PEPS....2...13G    Altcode: 2015PESS....2...13G; 2015arXiv150406332G
  This paper presents an overview of results obtained during the CAWSES-II
  period on the short-term variability of the Sun and how it affects
  the near-Earth space environment. CAWSES-II was planned to examine
  the behavior of the solar-terrestrial system as the solar activity
  climbed to its maximum phase in solar cycle 24. After a deep minimum
  following cycle 23, the Sun climbed to a very weak maximum in terms
  of the sunspot number in cycle 24 (MiniMax24), so many of the results
  presented here refer to this weak activity in comparison with cycle
  23. The short-term variability that has immediate consequence to Earth
  and geospace manifests as solar eruptions from closed-field regions and
  high-speed streams from coronal holes. Both electromagnetic (flares)
  and mass emissions (coronal mass ejections - CMEs) are involved in
  solar eruptions, while coronal holes result in high-speed streams that
  collide with slow wind forming the so-called corotating interaction
  regions (CIRs). Fast CMEs affect Earth via leading shocks accelerating
  energetic particles and creating large geomagnetic storms. CIRs
  and their trailing high-speed streams (HSSs), on the other hand,
  are responsible for recurrent small geomagnetic storms and extended
  days of auroral zone activity, respectively. The latter leads to the
  acceleration of relativistic magnetospheric `killer' electrons. One
  of the major consequences of the weak solar activity is the altered
  physical state of the heliosphere that has serious implications for
  the shock-driving and storm-causing properties of CMEs. Finally,
  a discussion is presented on extreme space weather events prompted
  by the 23 July 2012 super storm event that occurred on the backside
  of the Sun. Many of these studies were enabled by the simultaneous
  availability of remote sensing and in situ observations from multiple
  vantage points with respect to the Sun-Earth line.

---------------------------------------------------------
Title: Influence of the Solar Wind Speed on the Propagation of
    Coronal Mass Ejections
Authors: Yashiro, S.; Tokumaru, M.; Fujiki, K.; Iju, T.; Akiyama,
   S.; Makela, P. A.; Gopalswamy, N.
2015AGUFMSH53B2497Y    Altcode:
  We investigate the influence of the solar wind (SW) on the propagation
  of a set of 191 coronal mass ejections (CMEs) near the Sun during
  the period 1996-2013. The CMEs were observed by LASCO on board SOHO
  and their source regions were identified using the CME-associated
  eruptive features (flares, filament eruptions, dimmings) in X-ray, EUV,
  microwave, and Hα observations. The SW speeds above the CME source
  regions were estimated from the interplanetary scintillation (IPS)
  observations from the Solar Terrestrial Environ Laboratory, Nagoya
  University. We considered only CMEs from close to the limb in order to
  avoid the projection effects. We also considered CMEs with at least 10
  height-time measurements in order to avoid the large uncertainty in the
  acceleration measurements. We confirm the well-known CME-SW relationship
  that the CMEs propagating faster (slower) than the ambient solar wind
  are likely to decelerate (accelerate). The correlation between the
  acceleration and the difference of the CME and the SW speeds is high
  with a correlation coefficient of -0.74, slightly lower compared to the
  one for CMEs associated with interplanetary radio bursts (Gopalswamy
  et al. 2001, JGR, 106, 29219). There are many accelerating CMEs in
  our sample with a speed similar to the ambient solar wind speed. This
  could be due to selection effect because accelerating CMEs tend to
  remain visible longer than decelerating ones. We also found that CMEs
  originating from around the sources of the fast solar wind tend to be
  faster, indicating that the open magnetic fields above the CME source
  regions affect the CME propagation.

---------------------------------------------------------
Title: Comparison of the 26 May 2012 SEP Event with the 3 November
    2011 SEP Event
Authors: Makela, P. A.; Gopalswamy, N.; Thakur, N.; Xie, H.
2015AGUFMSH33B2465M    Altcode:
  We compare the solar and interplanetary events associated with two
  large solar energetic particle (SEP) events on 26 May 2012 and 3
  November 2011. Both SEP events were detected at three longitudinally
  widely separated locations by STEREO A and B spacecraft (more than 100
  deg away from Earth) and the Wind and SOHO spacecraft near Earth. In
  Earth view, the November 2011 eruption occurred far behind the east
  limb at N09E154, whereas the May 2012 eruption occurred closer to the
  west limb at N15W121, suggesting that SEPs accelerated during the 2012
  event might have easier access to Earth. Even though the 2012 event
  was more intense in the GOES &gt;10 MeV proton channel (peak intensity
  14 pfu) than the 2011 event (peak intensity 4 pfu), we find that the
  latter event was more intense at higher energies (&gt; 40 MeV). Also,
  the initial rise at lower energies was slightly faster for the 2011
  event as measured by SOHO/ERNE. In addition, the CME associated with
  the May 2012 event was faster with an estimated space speed of ~2029
  km/s than that in the November 2011 event (1188 km/s). STEREO/EUVI
  images of the associated post-eruption arcades (PEAs) indicate that
  their orientations were different: the PEA of the May 2012 event had
  a high inclination (north-south), while the inclination of the PEA
  of the 2011 event was more moderate. Differences in the flux rope
  orientation may also have effect on the longitudinal extent of the
  SEP events. These observations suggest that the dependence of solar
  proton intensities on the observer's longitudinal distance from the
  solar source is more complex than traditionally assumed.

---------------------------------------------------------
Title: Diffuse Interplanetary Radio Emission (DIRE) Accompanying
    Type II Radio Bursts
Authors: Teklu, T. B.; Gopalswamy, N.; Makela, P. A.; Yashiro, S.;
   Akiyama, S.; Xie, H.
2015AGUFMSH51A2441T    Altcode:
  We report on an unusual drifting feature in the radio dynamic spectra
  at frequencies below 14 MHz observed by the Radio and Plasma Wave
  (WAVES) experiment on board the Wind spacecraft. We call this
  feature as "Diffuse Interplanetary Radio Emission (DIRE)". The DIRE
  events are generally associated with intense interplanetary type
  II radio bursts produced by shocks driven by coronal mass ejections
  (CMEs). DIREs drift like type II bursts in the dynamic spectra, but
  the drifting feature consist of a series of short-duration spikes
  (similar to a type I chain). DIREs occur at higher frequencies than
  the associated type II bursts, with no harmonic relationship with the
  type II burst. The onset of DIREs is delayed by several hours from
  the onset of the eruption. Comparing the radio dynamic spectra with
  white-light observations from the Solar and Heliospheric Observatory
  (SOHO) mission, we find that the CMEs are generally very energetic
  (fast and mostly halos). We suggest that the DIRE source is typically
  located at the flanks of the CME-driven shock that is still at lower
  heliocentric distances.

---------------------------------------------------------
Title: Type II Radio Bursts as Indicators of Space Weather Drivers
Authors: Gopalswamy, N.
2015AGUFMSH41F..04G    Altcode:
  Interplanetary type II radio bursts are important indicators of
  shock-driving coronal mass ejections (CMEs). CME-driven shocks
  are responsible for large solar energetic particle (SEP) events
  and sudden commencement/sudden impulse events recorded by ground
  magnetometers. The excellent overlap of the spatial domains probed
  by SOHO/STEREO coronagraphs with the spectral domains of Wind/WAVES
  and STEREO/WAVES has contributed enormously in understanding CMEs and
  shocks as space weather drivers. This paper is concerned with type II
  bursts of solar cycle 23 and 24 that had emission components down to
  kilometric wavelengths. CMEs associated with these bursts seem to be the
  best indicators of large SEP events, better than the halo CMEs. However,
  there are some differences between the type II bursts of the two cycles,
  which are explained based on the different states of the heliosphere
  in the two cycles. Finally, the type II burst characteristics of some
  recent extreme events are discussed.

---------------------------------------------------------
Title: Advancing the understanding of the Sun-Earth interaction—the
    Climate and Weather of the Sun-Earth System (CAWSES) II program
Authors: Tsuda, Toshitaka; Shepherd, Marianna; Gopalswamy, Nat
2015PEPS....2...28T    Altcode: 2015PESS....2...28T
  The Scientific Committee on Solar-Terrestrial Physics (SCOSTEP) of the
  International Council for Science (ICSU) implemented an international
  collaborative program called Climate and Weather of the Sun-Earth System
  (CAWSES), which was active from 2004 to 2008; this was followed by the
  CAWSES II program during the period of 2009-2013. The CAWSES program was
  aimed at improving the understanding of the coupled solar-terrestrial
  system, with special emphasis placed on the short-term (weather) and
  long-term (climate) variability of solar activities and their effects
  on and responses of Geospace and Earth's environment. Following the
  successful implementation of CAWSES, the CAWSES II program pursued
  four fundamental questions addressing the way in which the coupled
  Sun-Earth system operates over time scales ranging from minutes to
  millennia, namely, (1) What are the solar influences on the Earth's
  climate? (2) How will Geospace respond to an altered climate? (3) How
  does short-term solar variability affect the Geospace environment? and
  (4) What is the Geospace response to variable inputs from the lower
  atmosphere? In addition to these four major tasks, the SCOSTEP and
  CAWSES promoted E-science and informatics activities including the
  creation of scientific databases and their effective utilization in
  solar-terrestrial physics research. Capacity building activities were
  also enhanced during CAWSES II, and this represented an important
  contribution of SCOSTEP to the world's solar-terrestrial physics
  community. This introductory paper provides an overview of CAWSES
  II activities and serves as a preface to the dedicated review papers
  summarizing the achievements of the program's four task groups (TGs)
  and the E-science component.

---------------------------------------------------------
Title: a Roadmap to Advance Understanding of the Science of Space
    Weather
Authors: Schrijver, K.; Kauristie, K.; Aylward, A.; De Nardin, C. M.;
   Gibson, S. E.; Glover, A.; Gopalswamy, N.; Grande, M.; Hapgood, M. A.;
   Heynderickx, D.; Jakowski, N.; Kalegaev, V. V.; Lapenta, G.; Linker,
   J.; Liu, S.; Mandrini, C. H.; Mann, I. R.; Nagatsuma, T.; Nandy, D.;
   Obara, T.; O'Brien, T. P., III; Onsager, T. G.; Opgenoorth, H. J.;
   Terkildsen, M. B.; Valladares, C. E.; Vilmer, N.
2015AGUFMSH12A..01S    Altcode:
  There is a growing appreciation that the environmental conditions that
  we call space weather impact the technological infrastructure that
  powers the coupled economies around the world. With that comes the need
  to better shield society against space weather by improving forecasts,
  environmental specifications, and infrastructure design. A COSPAR/ILWS
  team recently completed a roadmap that identifies the scientific focus
  areas and research infrastructure that are needed to significantly
  advance our understanding of space weather of all intensities and of
  its implications and costs for society. This presentation provides a
  summary of the highest-priority recommendations from that roadmap.

---------------------------------------------------------
Title: Low-Frequency Type II Radio Detections and Coronagraph Data
    to Describe and Forecast the Propagation of 71 CMEs/Shocks
Authors: St Cyr, O. C.; Cremades, H.; Iglesias, F. A.; Xie, H.;
   Kaiser, M. L.; Gopalswamy, N.
2015AGUFMSH21B2401S    Altcode:
  Motivated by improving predictions of arrival times at Earth of
  shocks driven by coronal mass ejections (CMEs), we have analyzed 71
  Earth-directed events in different stages of their propagation. The
  study is primarily based on approximated locations of interplanetary
  (IP) shocks derived from Type-II radio emissions detected by the
  Wind/WAVES experiment during 1997-2007. Distance-time diagrams resulting
  from the combination of white-light corona, IP Type-II radio, and
  in situ data lead to the formulation of descriptive profiles of each
  CME's journey toward Earth. Furthermore, two different methods to track
  and predict the location of CME-driven IP shocks are presented. The
  linear method, solely based on Wind/WAVES data, arises after key
  modifications to a pre-existing technique that linearly projects the
  drifting low-frequency Type-II emissions to 1 AU. This upgraded method
  improves forecasts of shock arrival time by almost 50%. The second
  predictive method is proposed on the basis of information derived from
  the descriptive profiles, and relies on a single CME height-time point
  and on low-frequency Type-II radio emissions to obtain an approximate
  value of the shock arrival time at Earth. In addition, we discuss
  results on CME-radio emission associations, characteristics of IP
  propagation, and the relative success of the forecasting methods.

---------------------------------------------------------
Title: Requirements for an Operational Coronagraph
Authors: Howard, R.; Vourlidas, A.; Harrison, R. A.; Bisi, M. M.;
   Plunkett, S. P.; Socker, D. G.; Eyles, C. J.; Webb, D. F.; DeForest,
   C. E.; Davies, J. A.; Howard, T. A.; de Koning, C. A.; Gopalswamy,
   N.; Davila, J. M.; Tappin, J.; Jackson, B. V.
2015AGUFMSH14A..02H    Altcode:
  Coronal mass ejections (CMEs) have been shown to be the major driver
  of the non-recurrent space weather events and geomagnetic storms. The
  utility of continuously monitoring such events has been very effectively
  demonstrated by the LASCO experiment on the SOHO mission. However SOHO
  is aging, having been launched 20 years ago on Dec 2, 1995. The STEREO
  mission, in which two spacecraft in orbits about the sun are drifting
  away from earth, has shown the utility of multiple viewpoints off the
  sun-earth line. Up to now the monitoring of CMES has been performed
  by scientific instruments such as LASCO and SECCHI with capabilities
  beyond those required to record the parameters that are needed to
  forecast the impact at earth. However, there is great interest within
  the US NOAA and the UK Met Office to launch operational coronagraphs
  to L1 and L5. An ad-hoc group was formed to define the requirements
  of the L5 coronagraph. In this paper we present some requirements that
  must be met by operational coronagraphs. The Office of Naval Research
  is gratefully acknowledged.

---------------------------------------------------------
Title: Properties and geoeffectiveness of magnetic clouds during
    solar cycles 23 and 24
Authors: Gopalswamy, N.; Yashiro, S.; Xie, H.; Akiyama, S.; Mäkelä,
   P.
2015JGRA..120.9221G    Altcode: 2015arXiv151000906G
  We report on a study that compares the properties of magnetic clouds
  (MCs) during the first 73 months of solar cycles 23 and 24 in order
  to understand the weak geomagnetic activity in cycle 24. We find that
  the number of MCs did not decline in cycle 24, although the average
  sunspot number is known to have declined by ~40%. Despite the large
  number of MCs, their geoeffectiveness in cycle 24 was very low. The
  average Dst index in the sheath and cloud portions in cycle 24 was -33
  nT and -23 nT, compared to -66 nT and -55 nT, respectively, in cycle
  23. One of the key outcomes of this investigation is that the reduction
  in the strength of geomagnetic storms as measured by the Dst index
  is a direct consequence of the reduction in the factor VB<SUB>z</SUB>
  (the product of the MC speed and the out-of-the-ecliptic component of
  the MC magnetic field). The reduction in MC-to-ambient total pressure
  in cycle 24 is compensated for by the reduction in the mean MC speed,
  resulting in the constancy of the dimensionless expansion rate at 1
  AU. However, the MC size in cycle 24 was significantly smaller, which
  can be traced to the anomalous expansion of coronal mass ejections near
  the Sun reported by Gopalswamy et al. (2014a). One of the consequences
  of the anomalous expansion seems to be the larger heliocentric distance
  where the pressure balance between the CME flux ropes and the ambient
  medium occurs in cycle 24.

---------------------------------------------------------
Title: High-energy solar particle events in cycle 24
Authors: Gopalswamy, N.; Mäkelä, P.; Yashiro, S.; Xie, H.; Akiyama,
   S.; Thakur, N.
2015JPhCS.642a2012G    Altcode: 2015arXiv150706162G
  The Sun is already in the declining phase of cycle 24, but the
  paucity of high-energy solar energetic particle (SEP) events continues
  with only two ground level enhancement (GLE) events as of March 31,
  2015. In an attempt to understand this, we considered all the large SEP
  events of cycle 24 that occurred until the end of 2014. We compared
  the properties of the associated CMEs with those in cycle 23. We
  found that the CME speeds in the sky plane were similar, but almost
  all those cycle-24 CMEs were halos. A significant fraction of (16%)
  of the frontside SEP events were associated with eruptive prominence
  events. CMEs associated with filament eruption events accelerate slowly
  and attain peak speeds beyond the typical GLE release heights. When we
  considered only western hemispheric events that had good connectivity
  to the CME nose, there were only 8 events that could be considered as
  GLE candidates. One turned out to be the first GLE event of cycle 24
  (2012 May 17). In two events, the CMEs were very fast (&gt;2000 km/s)
  but they were launched into a tenuous medium (high Alfven speed). In the
  remaining five events, the speeds were well below the typical GLE CME
  speed (∼2000 km/s). Furthermore, the CMEs attained their peak speeds
  beyond the typical heights where GLE particles are released. We conclude
  that several factors contribute to the low rate of high-energy SEP
  events in cycle 24: (i) reduced efficiency of shock acceleration (weak
  heliospheric magnetic field), (ii) poor latitudinal and longitudinal
  connectivity), and (iii) variation in local ambient conditions (e.g.,
  high Alfven speed).

---------------------------------------------------------
Title: Low-Frequency Type-II Radio Detections and Coronagraph Data
    Employed to Describe and Forecast the Propagation of 71 CMEs/Shocks
Authors: Cremades, H.; Iglesias, F. A.; St. Cyr, O. C.; Xie, H.;
   Kaiser, M. L.; Gopalswamy, N.
2015SoPh..290.2455C    Altcode: 2015arXiv150501730C; 2015SoPh..tmp..136C
  Motivated by improving predictions of arrival times at Earth of
  shocks driven by coronal mass ejections (CMEs), we have analyzed 71
  Earth-directed events in different stages of their propagation. The
  study is primarily based on approximated locations of interplanetary
  (IP) shocks derived from Type-II radio emissions detected by the
  Wind/WAVES experiment during 1997 - 2007. Distance-time diagrams
  resulting from the combination of white-light corona, IP Type-II radio,
  and in-situ data lead to the formulation of descriptive profiles of
  each CME's journey toward Earth. Furthermore, two different methods
  for tracking and predicting the location of CME-driven IP shocks are
  presented. The linear method, solely based on Wind/WAVES data, arises
  after key modifications to a pre-existing technique that linearly
  projects the drifting low-frequency Type-II emissions to 1 AU. This
  upgraded method improves forecasts of shock-arrival times by almost 50
  %. The second predictive method is proposed on the basis of information
  derived from the descriptive profiles and relies on a single CME
  height-time point and on low-frequency Type-II radio emissions to obtain
  an approximate value of the shock arrival time at Earth. In addition,
  we discuss results on CME-radio emission associations, characteristics
  of IP propagation, and the relative success of the forecasting methods.

---------------------------------------------------------
Title: The Mild Space Weather in Solar Cycle 24
Authors: Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Xie,
   Hong; Makela, Pertti; Michalek, Grzegorz
2015arXiv150801603G    Altcode:
  The space weather is extremely mild during solar cycle 24: the number
  of major geomagnetic storms and high-energy solar energetic particle
  events are at the lowest since the dawn of the space age. Solar wind
  measurements at 1 AU using Wind and ACE instruments have shown that
  there is a significant drop in the density, magnetic field, total
  pressure, and Alfven speed in the inner heliosphere as a result of
  the low solar activity. The drop in large space weather events is
  disproportionately high because the number of energetic coronal mass
  ejections that cause these events has not decreased significantly. For
  example, the rate of halo CMEs, which is a good indicator of energetic
  CMEs, is similar to that in cycle 23, even though the sunspot
  number has declined by about 40%. The mild space weather seems to
  be a consequence of the anomalous expansion of CMEs due to the low
  ambient pressure in the heliosphere. The anomalous expansion results
  in the dilution of the magnetic contents of CMEs, so the geomagnetic
  storms are generally weak. CME driven shocks propagating through the
  weak heliospheric field are less efficient in accelerating energetic
  particles, so the particles do not attain high energies. Finally,
  we would like to point out that extreme events such as the 2012 July
  23 CMEs that occurred on the backside of the Sun and did not affect
  Earth except for a small proton event.

---------------------------------------------------------
Title: Kinematic and Energetic Properties of the 2012 March 12 Polar
    Coronal Mass Ejection
Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.
2015ApJ...809..106G    Altcode: 2015arXiv150704057G
  We report on the energetics of the 2012 March 12 polar coronal mass
  ejection (CME) originating from a southern latitude of ∼60°. The
  polar CME is similar to low-latitude (LL) CMEs in almost all respects:
  three-part morphology; post-eruption arcade (PEA), CME, and filament
  kinematics; CME mass and kinetic energy; and the relative thermal energy
  content of the PEA. From polarized brightness images, we estimate
  the CME mass, which is close to the average mass of LL CMEs. The
  CME kinetic energy (3.3 × 10<SUP>30</SUP> erg) is also typical of
  the general population of CMEs. From photospheric magnetograms, we
  estimate the free energy (1.8 × 10<SUP>31</SUP> erg) in the polar crown
  source region, which we find is sufficient to power the CME and the
  PEA. About 19% of the free energy went into the CME kinetic energy. We
  compute the thermal energy content of the PEA (2.3 × 10<SUP>29</SUP>
  erg) and find it to be a small fraction (6.8%) of the CME kinetic
  energy. This fraction is remarkably similar to that in active region
  CMEs associated with major flares. We also show that the 2012 March 12
  is one among scores of polar CMEs observed during the maximum phase of
  cycle 24. The cycle 24 polar crown prominence eruptions have the same
  rate of association with CMEs as those from LLs. This investigation
  supports the view that all CMEs are magnetically propelled from closed
  field regions, irrespective of their location on the Sun (polar crown
  filament regions, quiescent filament regions, or active regions).

---------------------------------------------------------
Title: GOES: An Indicator for GLEs?
Authors: Thakur, Neeharika; Gopalswamy, N.; Mäkelä, P.; Akiyama,
   S.; Yashiro, S.; Xie, H.
2015shin.confE.149T    Altcode:
  We surveyed all large solar energetic particle (SEP) events (intensity
  at least 10 pfu in the &gt;10 MeV GOES channel) in solar cycles 23
  and 24 to confirm the suggestion that ground level enhancements (GLEs)
  produce an intensity increase in the GOES &gt;700 MeV proton channel
  (Gopalswamy et al. 2014). The survey confirms this in all but two
  large SEP events: (1) the GLE of 6 May 1998 (GLE57) did not have GOES
  &gt;700 MeV protons and (2) the 8 November 2000 SEP event had GOES
  &gt;700 MeV protons but no GLE was recorded. We compare GLE57 with
  other similar GLEs, and the 8 November 2000 SEP event with those that
  showed similar intensity increases in the GOES &gt;700 MeV protons but
  produced GLEs. We find that because GOES &gt;700 MeV proton intensity
  enhancements are typically small for small GLEs; they are difficult to
  discern near solar minima due to higher background. Our results are
  consistent with previous findings that GLEs are generally observed
  when CME-driven shocks form at heights 1.2-1.9 solar radii (Rs) (GLE
  release occurs when the CMEs are at 2-6 Rs). Our study also supports
  the view that the nose region of the CME-shock may be accelerating GeV
  particles, but may not be detected due to poor latitudinal connectivity
  of the observer to the shock nose. We conclude that GOES &gt;700 MeV
  proton channel can be used as an indicator for GLEs with some rare
  exceptions. Use of GOES as a GLE indicator becomes especially important
  because the observation of small GLEs may be missed by sparsely located
  neutron monitors.

---------------------------------------------------------
Title: Observational Aspects of Particle Acceleration Resulting
    in GLEs
Authors: Gopalswamy, Nat
2015shin.confE.146G    Altcode:
  Ground Level Enhancement (GLE) events in cycle 24 have been extremely
  rare: only 2 events have been reported as of June 4, 2015, even though
  solar activity is already in the declining phase. In an attempt to
  understand this, we examined all the large SEP events of cycle 24
  that occurred until the end of 2014. We compared the properties of
  the SEP-associated CMEs with those in cycle 23. We found that the
  CME speeds in the sky plane are similar, but almost all the cycle-24
  CMEs were halos. A significant fraction of (13%) of the frontside SEP
  events were associated with eruptive prominence events. CMEs associated
  with filament eruption events accelerate slowly and attain peak speeds
  beyond the typical GLE release heights. When we considered only western
  hemispheric SEP events that had good latitudinal connectivity to the CME
  nose, there were only 8 candidate GLE events. One turned out to be the
  first GLE event of cycle 24 (17 May 2012). In two events, the CMEs were
  very fast (&gt;2000 km/s) but they were launched into a tenuous medium
  (high Alfven speed). In the remaining five events, the speeds were well
  below the average CME speed ( 2000 km/s) in GLE events. Furthermore,
  the CMEs attained their peak speeds beyond the typical heights where
  GLE particles are released. We conclude that there are several factors
  that seem to be responsible for the very low rate of high-energy
  SEP events in cycle 24: (i) reduced efficiency of shock acceleration
  (weak heliospheric magnetic field), (ii) large-ecliptic distance to
  solar sources of major eruptions (poor latitudinal connectivity), and
  (iii) variation in local ambient conditions (e.g., high Alfven speed).

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Title: Hierarchical relationship of DH and mDH type II bursts using
    the kinematic properties of the associated CMEs
Authors: Teklu, Tsega Berhane; Gopalswamy, N.; Mäkelä, P.; Yashiro,
   S.; Akiyama, S.; Xie, H.; Thakur, N.
2015shin.confE..51T    Altcode:
  Using type II radio bursts from WIND WAVES and the associated CMEs from
  SOHO LASCO, Gopalswamy et al., (2005) found a hierarchical relationship
  between the wavelength range of the type II bursts and CME kinetic
  energy. Under 'DH Type II bursts' they had included mDH, DH and DHkm
  bursts. (DH: Decameter-hectometric; m: metric; km: kilometric). In
  this work, we consider the pure DH and mDH subsets separately. We find
  that mDH have slightly larger average speed, larger halo fraction,
  and larger non-halo width. Despite these consistent relationships,
  DH CMEs have slightly larger association rate with SEPs than mDH
  CMEs. The DH CMEs in Gopalswamy et al. (2005) have a higher average
  speed because they include DH km CMEs, which are more energetic. The
  SEP association rate of DH and mDH type II bursts are much smaller than
  that of mkm type II bursts. The SEP sources are generally located in
  the western hemisphere because of magnetic connectivity requirement.

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Title: Filament Eruptions Outside of Active Regions as Sources of
    Large Solar Energetic Particle Events
Authors: Kahler, S.; Gopalswamy, N.; Makela, P.; Akiyama, S.; Yashiro,
   S.; Xie, H.; Thakur, N.
2015ICRC...34...48K    Altcode: 2015PoS...236...48K
  No abstract at ADS

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Title: Solar energetic particle association of fast and wide coronal
    mass ejections
Authors: Yashiro, Seiji; Gopalswamy, N.; Akiyama, S.; Mäkelä, P.;
   Xie, H.
2015shin.confE..47Y    Altcode:
  The occurrence of solar energetic particle (SEP) events in association
  with fast (speed ∼900 km/s) and wide (width ∼) coronal mass
  ejections (FW CMEs) was investigated. Source regions of the FW CMEs were
  identified using SOHO/EIT, STEREO/EUVI, and SDO/AIA images. Using STEREO
  EUV observations, we are able to determine the source locations of
  CMEs that occurred behind the limb with a high degree of accuracy. The
  &gt;10 MeV proton flux at Earth was examined using GOES/SEM. The
  &gt;10 MeV proton flux at the STEREO spacecraft was estimated using
  STEREO/HET, which detects energetic protons in 11 energy channels in
  the range 13.6 to 100 MeV. By fitting a power law to the STEREO data,
  we extrapolated the proton flux to the 10 - 150 MeV range as an estimate
  of the &gt;10 MeV proton flux. We examined the SEP associations of
  196 FW CMEs that occurred during 2006 December to 2014 September and
  found that (1) the SEP association rate peaked at the W61°, (2) the
  magnetically well-connected longitudes range from W20°-W93°, (3)
  the SEP association rate distribution is skewed: the eastern wing of
  the rate distribution drops slowly compared to the western wing, (4)
  all &gt;1700 km/s CMEs originating from the well-connected longitude
  are associated with the SEP events. We examined the preconditioning by
  preceding CMEs and found that all but one huge SEP event (∼1000 pfu)
  are preconditioned.

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Title: Energy Dependence of SEP Electron and Proton Onset Times
Authors: Xie, Hong; Makela, P.; Gopalswamy, N.; St. Cyr, O. C.
2015shin.confE..46X    Altcode:
  We study large solar energetic particle (SEP) events with &gt;
  10 MeV proton flux observed by GOES during solar cycle 24. Using
  multi-spacecraft observations from STEREO A, B and SOHO, we are able
  to determine accurately the solar particle release (SPR) time of
  SEP electrons and protons. We first compute connection angles (CA)
  between the solar events and magnetic foot-points connecting to each
  spacecraft. By choosing the smallest CA, we derive the electron and
  proton SPRs using electron fluxes from the SOHO Electron Proton and
  Helium Instrument (EPHIN), proton fluxes from the SOHO Energetic and
  Relativistic Nuclei and Electron instrument (ERNE), and from the High
  Energy Telescope (HET) on STEREO. We find that the proton SPRs inferred
  from high-energy channels (&gt; 50 MeV) are similar to electron SPRs;
  the proton SPRs inferred from lower energy channel (5.12 - 16.9 MeV)
  can be delayed from the electron SPRs from tens of minutes to hours,
  especially for SEPs with large pre-event flux levels, suggesting that
  lower-energy protons might be trapped for a long time or suffer more
  scattering than higher-energy protons. We also find that for some large
  SEP events, the observed EPHIN electron and ERNE proton intensity
  profiles show a double-peak feature. The onset of the first peak
  corresponds well to the associated Type III and metric Type II onset.

---------------------------------------------------------
Title: Earth-arrival of Coronal Mass Ejections originating from
    close to the Solar Disk Center
Authors: Akiyama, Sachiko; Yashiro, S.; Gopalswamy, N.; Mäkelä,
   P.; Xie, H.
2015shin.confE..97A    Altcode:
  Not all coronal mass ejections (CMEs) that originate from close to the
  solar disk center arrive at Earth due to various reasons. In order
  to find the fraction of CMEs that do reach Earth, we investigated a
  set of wide CMEs (width ∼ 60 degrees) originating from close to the
  disk center (Central Meridian Distance &lt; 30 degrees). Seventy such
  CMEs were identified in 2011 using SOHO and STEREO coronagraphs and
  heliospheric imagers. The solar sources of these CMEs were confirmed to
  be close to the disk center using images from the Atmospheric Imaging
  Assembly (AIA) on board the Solar Dynamics Observatory (SDO). We found
  that only about a third of the disk-center CMEs arrived at Earth. We
  examined the possible reasons for the non-arrival of the remaining
  CMEs and found that 1) 31% of CMEs faded out before reaching Earth,
  2) 27% were captured by following faster CMEs, and 3) 7% of CMEs left
  the ecliptic plane. The faded-out CMEs became invisible in STEREO/COR1
  (32%), COR2 (32%), or HI1 (36%) fields of view. We also investigated
  the geoeffectiveness of the Earth-arriving CMEs and found that only 17%
  (4/22) of them produced at least a moderate geomagnetic storm (Dst
  index &lt; -50 nT). The Dst index of the largest geomagnetic storms
  in our data set was -72 nT. In 2011 there were 3 intense geomagnetic
  storms (Dst Index &lt; -100 nT), but all of them were produced by
  non-disk center CMEs and hence they are not in our sample. We also
  found that the Earth-arriving CMEs are faster than the fading-out CMEs
  ( 700 km/s vs. 300 km/s) from COR1 to COR2 FOVs. We conclude that
  only a tiny fraction of wide CMEs originating from the disk center
  are geoeffective (4/70 or 6%). In the future work, we are planning to
  expand study period to increase the sample size.

---------------------------------------------------------
Title: White-light and radio observations of CME interaction during
    the 2013 May 22 solar energetic particle event
Authors: Mäkelä, Pertti; Gopalswamy, N.; Yashiro, S.; Xie, H.;
   Reiner, M. J.
2015shin.confE..96M    Altcode:
  On 2013 May 22, the SOHO/LASCO coronagraph observed two coronal mass
  ejections (CMEs) in close sequence at 08:48 UT and 13:25 UT originating
  from the same NOAA AR11745 located at N15W70. The CMEs were associated
  with a large increase of proton flux with a peak intensity of 1660
  protons cm^-2 sr^-1 s^-1 in the GOES &gt;10 MeV integral channel. During
  the event, the following, faster CME with a sky-plane speed of 1466 km/s
  overtook and interacted with the preceding, slower CME with a sky-plane
  speed of 687 km/s. The LASCO white-light images clearly revealed that
  during the interaction the preceding CME accelerated while the following
  CME decelerated. The CME interaction also caused an enhancement of type
  II radio emission detected at the decameter-hectometric wavelengths by
  radio instruments on the Wind and STEREO spacecraft. The source location
  of the type II enhancement estimated by direction finding technique
  confirmed that the radio emission was coming from the interaction
  region. The drift rate of the type II radio burst was also seen to be
  different after the merger of the CMEs.

---------------------------------------------------------
Title: Estimating the Height of CMEs Associated with a Major SEP
    Event at the Onset of the Metric Type II Radio Burst during Solar
    Cycles 23 and 24
Authors: Mäkelä, P.; Gopalswamy, N.; Akiyama, S.; Xie, H.;
   Yashiro, S.
2015ApJ...806...13M    Altcode:
  We studied the coronal mass ejection (CME) height at the onset of 59
  metric type II radio bursts associated with major solar energetic
  particle (SEP) events, excluding ground level enhancements (GLEs),
  during solar cycles 23 and 24. We calculated CME heights using a simple
  flare-onset method used by Gopalswamy et al. to estimate CME heights
  at the metric type II onset for cycle 23 GLEs. We found the mean CME
  height for non-GLE events (1.72 R<SUB>⊙</SUB>) to be ∼12% greater
  than that (1.53 R<SUB>⊙</SUB>) for cycle 23 GLEs. The difference could
  be caused by more impulsive acceleration of the GLE-associated CMEs. For
  cycle 24 non-GLE events, we compared the CME heights obtained using the
  flare-onset method and the three-dimensional spherical-shock fitting
  method and found the correlation to be good (CC = 0.68). We found the
  mean CME height for cycle 23 non-GLE events (1.79 R<SUB>⊙</SUB>) to be
  greater than that for cycle 24 non-GLE events (1.58 R<SUB>⊙</SUB>),
  but statistical tests do not definitely reject the possibility of
  coincidence. We suggest that the lower formation height of the shocks
  during cycle 24 indicates a change in the Alfvén speed profile because
  solar magnetic fields are weaker and plasma density levels are closer
  to the surface than usual during cycle 24. We also found that complex
  type III bursts showing diminution of type III emission in the 7-14
  MHz frequency range are more likely associated with events with a
  CME height at the type II onset above 2 R<SUB>⊙</SUB>, supporting
  suggestions that the CME/shock structure causes the feature.

---------------------------------------------------------
Title: Understanding space weather to shield society: A global road
    map for 2015-2025 commissioned by COSPAR and ILWS
Authors: Schrijver, Carolus J.; Kauristie, Kirsti; Aylward, Alan D.;
   Denardini, Clezio M.; Gibson, Sarah E.; Glover, Alexi; Gopalswamy,
   Nat; Grande, Manuel; Hapgood, Mike; Heynderickx, Daniel; Jakowski,
   Norbert; Kalegaev, Vladimir V.; Lapenta, Giovanni; Linker, Jon A.;
   Liu, Siqing; Mandrini, Cristina H.; Mann, Ian R.; Nagatsuma, Tsutomu;
   Nandy, Dibyendu; Obara, Takahiro; Paul O'Brien, T.; Onsager, Terrance;
   Opgenoorth, Hermann J.; Terkildsen, Michael; Valladares, Cesar E.;
   Vilmer, Nicole
2015AdSpR..55.2745S    Altcode: 2015arXiv150306135S
  There is a growing appreciation that the environmental conditions
  that we call space weather impact the technological infrastructure
  that powers the coupled economies around the world. With that comes
  the need to better shield society against space weather by improving
  forecasts, environmental specifications, and infrastructure design. We
  recognize that much progress has been made and continues to be made
  with a powerful suite of research observatories on the ground and
  in space, forming the basis of a Sun-Earth system observatory. But
  the domain of space weather is vast - extending from deep within the
  Sun to far outside the planetary orbits - and the physics complex
  - including couplings between various types of physical processes
  that link scales and domains from the microscopic to large parts
  of the solar system. Consequently, advanced understanding of space
  weather requires a coordinated international approach to effectively
  provide awareness of the processes within the Sun-Earth system through
  observation-driven models. This roadmap prioritizes the scientific focus
  areas and research infrastructure that are needed to significantly
  advance our understanding of space weather of all intensities and
  of its implications for society. Advancement of the existing system
  observatory through the addition of small to moderate state-of-the-art
  capabilities designed to fill observational gaps will enable significant
  advances. Such a strategy requires urgent action: key instrumentation
  needs to be sustained, and action needs to be taken before core
  capabilities are lost in the aging ensemble. We recommend advances
  through priority focus (1) on observation-based modeling throughout the
  Sun-Earth system, (2) on forecasts more than 12 h ahead of the magnetic
  structure of incoming coronal mass ejections, (3) on understanding
  the geospace response to variable solar-wind stresses that lead to
  intense geomagnetically-induced currents and ionospheric and radiation
  storms, and (4) on developing a comprehensive specification of space
  climate, including the characterization of extreme space storms to guide
  resilient and robust engineering of technological infrastructures. The
  roadmap clusters its implementation recommendations by formulating
  three action pathways, and outlines needed instrumentation and research
  programs and infrastructure for each of these. An executive summary
  provides an overview of all recommendations.

---------------------------------------------------------
Title: Large Solar Energetic Particle Events Associated with Filament
    Eruptions Outside of Active Regions
Authors: Gopalswamy, N.; Mäkelä, P.; Akiyama, S.; Yashiro, S.; Xie,
   H.; Thakur, N.; Kahler, S. W.
2015ApJ...806....8G    Altcode: 2015arXiv150400709G
  We report on four large filament eruptions (FEs) from solar cycles 23
  and 24 that were associated with large solar energetic particle (SEP)
  events and interplanetary type II radio bursts. The post-eruption
  arcades corresponded mostly to C-class soft X-ray enhancements,
  but an M1.0 flare was associated with one event. However, the
  associated coronal mass ejections (CMEs) were fast (speeds ∼ 1000
  km s<SUP>-1</SUP>) and appeared as halo CMEs in the coronagraph field
  of view. The interplanetary type II radio bursts occurred over a wide
  wavelength range, indicating the existence of strong shocks throughout
  the inner heliosphere. No metric type II bursts were present in
  three events, indicating that the shocks formed beyond 2-3 Rs. In one
  case, there was a metric type II burst with low starting frequency,
  indicating a shock formation height of ∼2 Rs. The FE-associated SEP
  events did have softer spectra (spectral index &gt;4) in the 10-100
  MeV range, but there were other low-intensity SEP events with spectral
  indices ≥4. Some of these events are likely FE-SEP events, but were
  not classified as such in the literature because they occurred close
  to active regions. Some were definitely associated with large active
  region flares, but the shock formation height was large. We definitely
  find a diminished role for flares and complex type III burst durations
  in these large SEP events. Fast CMEs and shock formation at larger
  distances from the Sun seem to be the primary characteristics of the
  FE-associated SEP events.

---------------------------------------------------------
Title: The Peculiar Behavior of Halo Coronal Mass Ejections in Solar
    Cycle 24
Authors: Gopalswamy, N.; Xie, H.; Akiyama, S.; Mäkelä, P.; Yashiro,
   S.; Michalek, G.
2015ApJ...804L..23G    Altcode: 2015arXiv150401797G
  We report on the remarkable finding that the halo coronal mass ejections
  (CMEs) in cycle 24 are more abundant than in cycle 23, although the
  sunspot number in cycle 24 has dropped by ∼40%. We also find that
  the distribution of halo-CME source locations is different in cycle 24:
  the longitude distribution of halos is much flatter with the number of
  halos originating at a central meridian distance ≥slant 60{}^\circ
  twice as large as that in cycle 23. On the other hand, the average
  speed and associated soft X-ray flare size are the same in both cycles,
  suggesting that the ambient medium into which the CMEs are ejected is
  significantly different. We suggest that both the higher abundance and
  larger central meridian longitudes of halo CMEs can be explained as
  a consequence of the diminished total pressure in the heliosphere in
  cycle 24. The reduced total pressure allows CMEs to expand more than
  usual making them appear as halos.

---------------------------------------------------------
Title: Geometrical Relationship Between Interplanetary Flux Ropes
    and Their Solar Sources
Authors: Marubashi, K.; Akiyama, S.; Yashiro, S.; Gopalswamy, N.;
   Cho, K. -S.; Park, Y. -D.
2015SoPh..290.1371M    Altcode: 2015SoPh..tmp...46M
  We investigated the physical connection between interplanetary flux
  ropes (IFRs) near Earth and coronal mass ejections (CMEs) by comparing
  the magnetic field structures of IFRs and CME source regions. The
  analysis is based on the list of 54 pairs of ICMEs (interplanetary
  coronal mass ejections) and CMEs that are taken to be the most probable
  solar source events. We first attempted to identify the flux rope
  structure in each of the 54 ICMEs by fitting models with a cylinder
  and torus magnetic field geometry, both with a force-free field
  structure. This analysis determined the possible geometries of the
  identified flux ropes. Then we compared the flux rope geometries with
  the magnetic field structure of the solar source regions. We obtained
  the following results: (1) Flux rope structures are seen in 51 ICMEs
  out of the 54. The result implies that all ICMEs have an intrinsic
  flux rope structure, if the three exceptional cases are attributed to
  unfavorable observation conditions. (2) It is possible to find flux rope
  geometries with the main axis orientation close to the orientation of
  the magnetic polarity inversion line (PIL) in the solar source regions,
  the differences being less than 25°. (3) The helicity sign of an IFR
  is strongly controlled by the location of the solar source: flux ropes
  with positive (negative) helicity are associated with sources in the
  southern (northern) hemisphere (six exceptions were found). (4) Over
  two-thirds of the sources in the northern hemisphere are concentrated
  along PILs with orientations of 45° ± 30° (measured clockwise from
  the east), and over two-thirds in the southern hemisphere along PILs
  with orientations of 135° ± 30°, both corresponding to the Hale
  boundaries. These results strongly support the idea that a flux rope
  with the main axis parallel to the PIL erupts in a CME and that the
  erupted flux rope propagates through the interplanetary space with
  its orientation maintained and is observed as an IFR.

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Title: Dynamics of CMEs in the LASCO Field of View
Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S.; Bronarska, K.
2015SoPh..290..903M    Altcode: 2015SoPh..tmp...20M
  A large set (16 000) of coronal mass ejections (CMEs) observed during
  1996 - 2011 was selected to study their dynamics in the LASCO field of
  view (LFOV). These events were selected based on the criterion that at
  least three height-time measurements were available for each CME. The
  height-time measurements included in the SOHO/LASCO catalog were used
  to determine velocities and accelerations of the respective CMEs at
  successive distances from the Sun. Next, these parameters were sorted
  into 30 subsamples depending on the distance from the Sun at which
  they were determined. The mean velocities and accelerations calculated
  for the successive distance-dependent subsamples of CMEs were used to
  study their dynamics. We demonstrate that CMEs in the LFOV manifest
  three distinct phases of propagation: (i) The propelling Lorentz
  force dominates the dynamics of CMEs in the inner (C2 LASCO) FOV,
  (ii) a stable propagation occurs as a result of the balance between
  the propelling and drag forces, (iii) the drag force dominates at
  the outer edge of the LFOV. When we considered different categories
  of CME separately, we found different acceleration-distance profiles
  for different categories.

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Title: The Dynamics of Eruptive Prominences
Authors: Gopalswamy, Nat
2015ASSL..415..381G    Altcode: 2014arXiv1407.2594G
  This chapter discusses the dynamical properties of eruptive prominences
  in relation to coronal mass ejections (CMEs). The fact that eruptive
  prominences are a part of CMEs is emphasized in terms of their
  physical association and kinematics. The continued propagation of
  prominence material into the heliosphere is illustrated using in-situ
  observations. The solar-cycle variation of eruptive prominence locations
  is discussed with a particular emphasis on the rush-to-the-pole (RTTP)
  phenomenon. One of the consequences of the RTTP phenomenon is polar
  CMEs, which are shown to be similar to the low-latitude CMEs. This
  similarity is important because it provides important clues to
  the mechanism by which CMEs erupt. The nonradial motion of CMEs
  is discussed, including the deflection by coronal holes that have
  important space weather consequences. Finally, the implications of
  the presented observations for CME modeling are outlined.

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Title: Instant: An Innovative L5 Small Mission Concept for Coordinated
    Science with Solar Orbiter and Solar Probe Plus
Authors: Lavraud, B.; Liu, Y. D.; Harrison, R. A.; Liu, W.;
   Auchere, F.; Gan, W.; Lamy, P. L.; Xia, L.; Eastwood, J. P.;
   Wimmer-Schweingruber, R. F.; Zong, Q.; Rochus, P.; Maksimovic, M.;
   Temmer, M.; Escoubet, C. P.; Kilpua, E.; Rouillard, A. P.; Davies,
   J. A.; Vial, J. C.; Gopalswamy, N.; Bale, S. D.; Li, G.; Howard,
   T. A.; DeForest, C. E.
2014AGUFMSH21B4109L    Altcode:
  We will present both the science objectives and related instrumentation
  of a small solar and heliospheric mission concept, INSTANT:
  INvestigation of Solar-Terrestrial Activity aNd Transients. It will be
  submitted as an opportunity to the upcoming ESA-China S-class mission
  call later this year. This concept was conceived to allow innovative
  measurements and unprecedented, early determination of key properties
  of Earthbound CMEs from the L5 vantage point. Innovative measurements
  will include magnetic field determination in the corona thanks to
  Hanle measurement in Lyman-α and polarized heliospheric imaging
  for accurate determination of CME trajectories. With complementary
  in situ measurements, it will uniquely permit solar storm science,
  solar storm surveillance, and synergy with Solar Orbiter and Solar
  Probe Plus (the ESA-China S2 mission launch is planned in 2021).

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Title: The Relation Between Large-Scale Coronal Propagating Fronts
    and Type II Radio Bursts
Authors: Nitta, Nariaki V.; Liu, Wei; Gopalswamy, Nat; Yashiro, Seiji
2014SoPh..289.4589N    Altcode: 2014arXiv1409.4754N
  Large-scale, wave-like disturbances in extreme-ultraviolet (EUV) and
  type II radio bursts are often associated with coronal mass ejections
  (CMEs). Both phenomena may signify shock waves driven by CMEs. Taking
  EUV full-disk images at an unprecedented cadence, the Atmospheric
  Imaging Assembly (AIA) onboard the Solar Dynamics Observatory has
  observed the so-called EIT waves or large-scale coronal propagating
  fronts (LCPFs) from their early evolution, which coincides with the
  period when most metric type II bursts occur. This article discusses the
  relation of LCPFs as captured by AIA with metric type II bursts. We show
  examples of type II bursts without a clear LCPF and fast LCPFs without
  a type II burst. Part of the disconnect between the two phenomena may
  be due to the difficulty in identifying them objectively. Furthermore,
  it is possible that the individual LCPFs and type II bursts may reflect
  different physical processes and external factors. In particular,
  the type II bursts that start at low frequencies and high altitudes
  tend to accompany an extended arc-shaped feature, which probably
  represents the 3D structure of the CME and the shock wave around it,
  and not just its near-surface track, which has usually been identified
  with EIT waves. This feature expands and propagates toward and beyond
  the limb. These events may be characterized by stretching of field
  lines in the radial direction and may be distinct from other LCPFs,
  which may be explained in terms of sudden lateral expansion of the
  coronal volume. Neither LCPFs nor type II bursts by themselves serve
  as necessary conditions for coronal shock waves, but these phenomena
  may provide useful information on the early evolution of the shock
  waves in 3D when both are clearly identified in eruptive events.

---------------------------------------------------------
Title: Vision for the Future of Lws TR&amp;T
Authors: Schwadron, N.; Mannucci, A. J.; Antiochos, S. K.;
   Bhattacharjee, A.; Gombosi, T. I.; Gopalswamy, N.; Kamalabadi, F.;
   Linker, J.; Pilewskie, P.; Pulkkinen, A. A.; Spence, H. E.; Tobiska,
   W. K.; Weimer, D. R.; Withers, P.; Bisi, M. M.; Kuznetsova, M. M.;
   Miller, K. L.; Moretto, T.; Onsager, T. G.; Roussev, I. I.; Viereck,
   R. A.
2014AGUFMSH33B..02S    Altcode:
  The Living With a Star (LWS) program addresses acute societal
  needs for understanding the effects of space weather and developing
  scientific knowledge to support predictive capabilities. Our society's
  heavy reliance on technologies affected by the space environment,
  an enormous number of airline customers, interest in space tourism,
  and the developing plans for long-duration human exploration space
  missions are clear examples that demonstrate urgent needs for space
  weather models and detailed understanding of space weather effects and
  risks. Since its inception, the LWS program has provided a vehicle
  to innovate new mechanisms for conducting research, building highly
  effective interdisciplinary teams, and ultimately in developing the
  scientific understanding needed to transition research tools into
  operational models that support the predictive needs of our increasingly
  space-reliant society. The advances needed require broad-based
  observations that cannot be obtained by large missions alone. The
  Decadal Survey (HDS, 2012) outlines the nation's needs for scientific
  development that will build the foundation for tomorrow's space weather
  services. Addressing these goals, LWS must develop flexible pathways
  to space utilizing smaller, more diverse and rapid development of
  observational platforms. Expanding utilization of ground-based assets
  and shared launches will also significantly enhance opportunities
  to fulfill the growing LWS data needs. Partnerships between NASA
  divisions, national/international agencies, and with industry will
  be essential for leveraging resources to address increasing societal
  demand for space weather advances. Strengthened connections to user
  communities will enhance the quality and impact of deliverables from
  LWS programs. Thus, we outline the developing vision for the future of
  LWS, stressing the need for deeper scientific understanding to improve
  forecasting capabilities, for more diverse data resources, and for
  project deliverables that address the growing needs of user communities.

---------------------------------------------------------
Title: Association Rate of Major Sep Events As a Function of CME
    Speed and Source Longitude
Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.; Makela, P. A.;
   Xie, H.
2014AGUFMSH43A4186Y    Altcode:
  We report on the fraction of fast and wide coronal mass ejections
  (FW CMEs; speed&gt;900 km/s; width&gt;60°) that produce solar
  energetic particle (SEP) events. Source regions of the FW CMEs were
  identified using SOHO/EIT, STEREO/EUVI, and SDO/AIA. Using STEREO EUV
  observations, we are able to determine the source locations behind
  the west limb with a high degree of accuracy. The &gt;10 MeV proton
  flux at Earth was examined using GOES/SEM. The &gt;10 MeV proton flux
  at the STEREO spacecraft was estimated using STEREO/HET, which detects
  energetic protons in 11 channels from 13.6 to 100 MeV. We extrapolated
  the proton flux in the 10 - 150 MeV range with a power-law fit and
  derived the corresponding &gt;10 MeV proton flux. For each FW CME,
  we have three proton flux values for three different relative source
  longitudes with respect to the observer. The SEP association rate is
  determined by dividing the number of SEP-producing CMEs by the total
  number of events in each 20° bin of the relative source longitude. We
  found that the SEP association rate peaked at the W60°-W80° bin and
  the magnetically well-connected longitudes range from W20°-W100°. We
  also found that the rate distribution is skewed: the eastern wing of
  the rate distribution drops slowly compared to the western wing. This
  indicates that the eastern CMEs (longitude &lt; 0°) have a better
  chance to reach the magnetic field line connected to Earth than the
  far-behind-the-west-limb (longitude &gt; 120°) CMEs.

---------------------------------------------------------
Title: Estimation of Reconnection Flux using Post-eruption Arcades
    and Prediction of Bz at Earth
Authors: Gopalswamy, N.; Xie, H.; Yashiro, S.; Akiyama, S.
2014AGUFMSH21C4139G    Altcode:
  Coronal mass ejections (CMEs) and flares share the same eruption
  process as has been confirmed from various aspects of the two
  phenomena. In particular, the post-eruption arcade and the CME flux
  rope are formed out of the same reconnection process. It is customary
  to compute the flare reconnection flux from the flare-ribbon area and
  photospheric/chromosphericmagnetic field strength. Here we report on a
  new method to compute the reconnection flux from post-eruption arcades
  (PEAs). Instead of counting the ribbon pixels in a series of images,
  we simply measure the area under PEAs after the flare maximum and the
  underlying photospheric magnetic field. The reconnection flux is then
  half of the product of these two quantities. We illustrate this method
  using specific examples and show that the ribbon and arcade methods
  yield very similar results. We show that this method provides a simple
  means of predicting the 1-AU flux rope magnetic field (including Bz)
  from measurements made near the Sun.

---------------------------------------------------------
Title: Factors Affecting the Occurrence of Large Solar Energetic
    Particle Events
Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Xie, H.; Makela,
   P. A.; Thakur, N.
2014AGUFMSH41D..07G    Altcode:
  In order to understand the paucity of high-energy solar energetic
  particle (SEP) events in solar cycle 24, we examined all major eruptions
  (soft X-ray flare size ≥M5.0) on the front side of the Sun during
  the period from December 1, 2008 to January 31, 2014. There were 59
  such eruptions that were associated with CMEs. When a flux rope was
  fitted to the white-light CMEs observed by SOHO and STEREO it was found
  that the CME sources were on the disk only for 55 eruptions. There
  were 16 large SEP events (proton intensity ≥10 pfu in the &gt;10
  MeV channel) detected by GOES and 4 by STEREO-B in association with
  these eruptions. When the CMEs were grouped according to their speeds
  (&lt;1500 km/s and ≥ 1500 km/s) it was found that only three of
  the &lt;1500 km/s CMEs (or 11%) were associated with large SEP events
  compared to 17 or (61%) of the ≥ 1500 km/s CMEs. This result confirms
  the importance of CME speed for SEP association. In fact there were
  ten other large SEP events with flare size &lt;M5.0, but associated
  with fast CMEs, suggesting that the flare size does not determine SEP
  association. In order to narrow down the properties of CMEs that produce
  GLE events, we divided the SEP-associated CMEs into a different speed
  range: ≥2000 km/s and 1500-1999 km/s. We also required that the CMEs
  originated from the longitudinal range of W20 to W90 (traditional GLE
  longitudes). There were sixteen such events, 6 with speed in the range
  1500-1999 km/s and 10 with ≥2000 km/s. When we further applied the
  criterion that the latitudinal distance of the CME sources from the
  ecliptic must be within ±13o (Gopalswamy et al. 2013 ApJL 765, L30),
  we found that there were only four CMEs that met this criterion. One
  of the four was the GLE event of 2012 May 17 whose CME speed was only
  slightly less than 2000 km/s. The 2011 August 9 CME was ejected into
  a tenuous medium, which means the shock was likely weak due to higher
  ambient Alfven speed, even though the CME speed was well above 2000
  km/s. The speed of the 2011 June 7 CME (1680 km/s) was well below the
  typical speed of GLE CMEs. The last one, the 2013 May 22 event was
  an interacting CME event, but the speed of the primary CME was only
  1880 km/s. Thus we conclude that the CME speed, the ecliptic distance
  of the CME source, and the ambient conditions are all important in
  deciding whether an SEP event would have GLE particles. Work supported
  by NASA's Living with a Star Program.

---------------------------------------------------------
Title: High Energy Particle Events in Solar Cycles 23 and 24
Authors: Thakur, N.; Gopalswamy, N.; Makela, P. A.; Yashiro, S.;
   Akiyama, S.; Xie, H.
2014AGUFMSH43A4190T    Altcode:
  We present a study of high-energy solar energetic particle (SEP) events
  in solar cycles 23 and 24 using GOES data. We selected large SEP events,
  which showed intensity enhancements in the &gt;500 MeV and &gt;700 MeV
  GOES energy channels. A study of cycle 24 and the first half of cycle
  23 ground level enhancements (GLEs) by Gopalswamy et al. 2014 showed
  that typically, SEP events with intensity enhancement at &gt;700 MeV
  have been associated with GLEs. We have extended the survey to cover
  the whole cycle 23. Our preliminary survey confirms this to be true
  for all except for three cases. There were two GLEs (1998/05/06 and
  2006/12/06) for which a clear increase in &gt;700 MeV protons was not
  observed by GOES. There was one high energy SEP event (2000/11/08), for
  which GOES observed &gt;700 MeV protons but no GLE was produced. Here
  we compare all the high-energy particle events from cycles 23 and
  24 with GLEs. We also compare energy spectra of all high-energy SEP
  events with those that produced GLEs. Work supported by NASA's Living
  with a Star Program. Ref.: Gopalswamy et al. 2014, GRL, 41, 2673

---------------------------------------------------------
Title: Major solar eruptions and high-energy particle events during
    solar cycle 24
Authors: Gopalswamy, Nat; Xie, Hong; Akiyama, Sachiko; Mäkelä,
   Pertti A.; Yashiro, Seiji
2014EP&S...66..104G    Altcode: 2014arXiv1408.3617G
  We report on a study of all major solar eruptions that occurred on
  the frontside of the Sun during the rise to peak phase of cycle 24
  (first 62 months) in order to understand the key factors affecting the
  occurrence of large solar energetic particle events (SEPs) and ground
  level enhancement (GLE) events. The eruptions involve major flares
  with soft X-ray peak flux ≥ 5.0 x10<SUP>-5</SUP> Wm<SUP>-2</SUP>
  (i.e., flare size ≥ M5.0) and accompanying coronal mass ejections
  (CMEs). The selection criterion was based on the fact that the only
  front-side GLE in cycle 24 (GLE 71) had a flare size of M5.1. Only
  approximately 37% of the major eruptions from the western hemisphere
  resulted in large SEP events. Almost the same number of large SEP
  events was produced in weaker eruptions (flare size &lt; M5.0),
  suggesting that the soft X-ray flare is not a good indicator of SEP
  or GLE events. On the other hand, the CME speed is a good indicator of
  SEP and GLE events because it is consistently high supporting the shock
  acceleration mechanism. We found the CME speed, magnetic connectivity
  to Earth (in longitude and latitude), and ambient conditions as the
  main factors that contribute to the lack of high-energy particle
  events during cycle 24. Several eruptions poorly connected to Earth
  (eastern-hemisphere or behind-the-west-limb events) resulted in very
  large SEP events detected by the Solar Terrestrial Relations Observatory
  (STEREO) spacecraft. Some very fast CMEs, likely to have accelerated
  particles to GeV energies, did not result in a GLE event because of
  poor latitudinal connectivity. The stringent latitudinal requirement
  suggests that the highest-energy particles are likely accelerated
  in the nose part of shocks, while the lower energy particles are
  accelerated at all parts. There were also well-connected fast CMEs,
  which did not seem to have accelerated high-energy particles due to
  possible unfavorable ambient conditions (high Alfven speed, overall
  reduction in acceleration efficiency in cycle 24).

---------------------------------------------------------
Title: Strategic Science to Address Current and Future Space
    Weather Needs
Authors: Mannucci, A. J.; Schwadron, N.; Antiochos, S. K.;
   Bhattacharjee, A.; Bisi, M. M.; Gopalswamy, N.; Kamalabadi, F.;
   Pulkkinen, A. A.; Tobiska, W. K.; Weimer, D. R.; Withers, P.
2014AGUFMSM24A..09M    Altcode:
  NASA's Living With a Star (LWS) program has contributed a wealth of
  scientific knowledge that is relevant to space weather and user needs. A
  targeted approach to science questions has resulted in leveraging
  new scientific knowledge to improve not only our understanding of the
  Heliophysics domain, but also to develop predictive capabilities in key
  areas of LWS science. This fascinating interplay between science and
  applications promises to benefit both domains. Scientists providing
  feedback to the LWS program are now discussing an evolution of the
  targeted approach that explicitly considers how new science improves,
  or enables, predictive capability directly. Long-term program goals
  are termed "Strategic Science Areas" (SSAs) that address predictive
  capabilities in six specific areas: geomagnetically induced currents,
  satellite drag, solar energetic particles, ionospheric total electron
  content, radio frequency scintillation induced by the ionosphere,
  and the radiation environment. SSAs are organized around user needs
  and the impacts of space weather on society. Scientists involved in
  the LWS program identify targeted areas of research that reference
  (or bear upon) societal needs. Such targeted science leads to new
  discoveries and is one of the valid forms of exploration. In this
  talk we describe the benefits of targeted science, and how addressing
  societal impacts in an appropriate way maintains the strong science
  focus of LWS, while also leading to its broader impacts.

---------------------------------------------------------
Title: Homologous flare-CME events and their metric type II radio
    burst association
Authors: Yashiro, S.; Gopalswamy, N.; Mäkelä, P.; Akiyama, S.;
   Uddin, W.; Srivastava, A. K.; Joshi, N. C.; Chandra, R.; Manoharan,
   P. K.; Mahalakshmi, K.; Dwivedi, V. C.; Jain, R.; Awasthi, A. K.;
   Nitta, N. V.; Aschwanden, M. J.; Choudhary, D. P.
2014AdSpR..54.1941Y    Altcode:
  Active region NOAA 11158 produced many flares during its disk
  passage. At least two of these flares can be considered as homologous:
  the C6.6 flare at 06:51 UT and C9.4 flare at 12:41 UT on February
  14, 2011. Both flares occurred at the same location (eastern edge of
  the active region) and have a similar decay of the GOES soft X-ray
  light curve. The associated coronal mass ejections (CMEs) were slow
  (334 and 337 km/s) and of similar apparent widths (43° and 44°), but
  they had different radio signatures. The second event was associated
  with a metric type II burst while the first one was not. The COR1
  coronagraphs on board the STEREO spacecraft clearly show that the
  second CME propagated into the preceding CME that occurred 50 min
  before. These observations suggest that CME-CME interaction might be
  a key process in exciting the type II radio emission by slow CMEs.

---------------------------------------------------------
Title: An Estimate of the Coronal Magnetic Field near a Solar Coronal
    Mass Ejection from Low-frequency Radio Observations
Authors: Hariharan, K.; Ramesh, R.; Kishore, P.; Kathiravan, C.;
   Gopalswamy, N.
2014ApJ...795...14H    Altcode:
  We report ground-based, low-frequency (&lt;100 MHz) radio imaging,
  spectral, and polarimeter observations of the type II radio burst
  associated with the solar coronal mass ejection (CME) that occurred
  on 2013 May 2. The spectral observations indicate that the burst has
  fundamental (F) and harmonic (H) emission components with split-band
  and herringbone structures. The imaging observations at 80 MHz indicate
  that the H component of the burst was located close to leading edge
  of the CME at a radial distance of r ≈ 2 R <SUB>⊙</SUB> in the
  solar atmosphere. The polarimeter observations of the type II burst,
  also at 80 MHz, indicate that the peak degree of circular polarization
  (dcp) corresponding to the emission generated in the corona ahead
  of and behind the associated MHD shock front are ≈0.05 ± 0.02 and
  ≈0.1 ± 0.01, respectively. We calculated the magnetic field B in
  the above two coronal regions by adopting the empirical relationship
  between the dcp and B for the harmonic plasma emission and the values
  are ≈(0.7-1.4) ± 0.2 G and ≈(1.4-2.8) ± 0.1 G, respectively.

---------------------------------------------------------
Title: Coronal Mass Ejections and Non-recurrent Forbush Decreases
Authors: Belov, A.; Abunin, A.; Abunina, M.; Eroshenko, E.; Oleneva,
   V.; Yanke, V.; Papaioannou, A.; Mavromichalaki, H.; Gopalswamy, N.;
   Yashiro, S.
2014SoPh..289.3949B    Altcode: 2014SoPh..tmp...73B
  Coronal mass ejections (CMEs) and their interplanetary counterparts
  (interplanetary coronal mass ejections, ICMEs) are responsible
  for large solar energetic particle events and severe geomagnetic
  storms. They can modulate the intensity of Galactic cosmic rays,
  resulting in non-recurrent Forbush decreases (FDs). We investigate
  the connection between CME manifestations and FDs. We used specially
  processed data from the worldwide neutron monitor network to pinpoint
  the characteristics of the recorded FDs together with CME-related data
  from the detailed online catalog based upon the Solar and Heliospheric
  Observatory (SOHO)/Large Angle and Spectrometric Coronagraph (LASCO)
  data. We report on the correlations of the FD magnitude to the CME
  initial speed, the ICME transit speed, and the maximum solar wind
  speed. Comparisons between the features of CMEs (mass, width, velocity)
  and the characteristics of FDs are also discussed. FD features for halo,
  partial halo, and non-halo CMEs are presented and discussed.

---------------------------------------------------------
Title: Ground Level Enhancement in the 2014 January 6 Solar Energetic
    Particle Event
Authors: Thakur, N.; Gopalswamy, N.; Xie, H.; Mäkelä, P.; Yashiro,
   S.; Akiyama, S.; Davila, J. M.
2014ApJ...790L..13T    Altcode: 2014arXiv1406.7172T
  We present a study of the 2014 January 6 solar energetic particle event
  which produced a small ground level enhancement (GLE), making it the
  second GLE of this unusual solar cycle 24. This event was primarily
  observed by the South Pole neutron monitors (increase of ~2.5%) while a
  few other neutron monitors recorded smaller increases. The associated
  coronal mass ejection (CME) originated behind the western limb and
  had a speed of 1960 km s<SUP>-1</SUP>. The height of the CME at the
  start of the associated metric type II radio burst, which indicates
  the formation of a strong shock, was measured to be 1.61 Rs using a
  direct image from STEREO-A/EUVI. The CME height at the time of the GLE
  particle release (determined using the South Pole neutron monitor data)
  was directly measured as 2.96 Rs based on STEREO-A/COR1 white-light
  observations. These CME heights are consistent with those obtained for
  GLE71, the only other GLE of the current cycle, as well as cycle-23 GLEs
  derived using back-extrapolation. GLE72 is of special interest because
  it is one of only two GLEs of cycle 24, one of two behind-the-limb GLEs,
  and one of the two smallest GLEs of cycles 23 and 24.

---------------------------------------------------------
Title: ISEST Program: International Stud of Earth-affecting Solar
    Transients
Authors: Zhang, Jie; Temmer, Manuela; Gopalswamy, Nat
2014shin.confE...7Z    Altcode:
  A new international program: International Study of Earth-affecting
  Solar Transients (IEST), is introduced. This program is one of
  the four scientific elements supported by the VarSITI (Variability
  of the Sun and Its Terrestrial Impact) project, a five-year long
  international-cross-discipline-collaboration project from 2014-2018,
  sponsored by the SCOSTEP (Scientific Committee of Solar-Terrestrial
  Physics). The aim of ISEST is to understand the origin, propagation and
  evolution of solar transients, including CMEs, CIRs and SEPs, through
  the space between the Sun and the Earth, and improve the prediction
  capability for space weather. Particular emphasis will be placed on the
  weak solar activity prevailing in Solar Cycle 24 (MiniMax24). The ISEST
  program consists of six working groups, encompassing data analysis,
  theoretical interpretation, numerical modeling, B-south challenge,
  event campaign study, and long-term MiniMax24 campaign studies. It
  is anticipated that the ISEST will create a comprehensive online
  database of Earth-affecting solar transients contributed by both
  observers and modelers. By the end of the program It is expected that
  the space weather prediction using solar observations will be improved
  significantly.

---------------------------------------------------------
Title: An Investigation of the Interplanetary Type II Radio Bursts
    Observed on 2012 January 19
Authors: Teklu, Tsega Berhane; Gopalswamy, N.; Mäkelä, P.; Yashiro,
   S.; Akiyama, S.; Xie, H.
2014shin.confE.155T    Altcode:
  We report on the analysis of the 2012 January 19 type II radio bursts
  observed by the Wind/WAVES experiment. The type II radio burst had two
  components. The first was a short-lived burst in decameter-hectometric
  (DH) while the second was long lived extending to kilometric (km)
  wavelengths. The short-lived type II burst had a high drift rate
  (- 5.4 kHz/s) while the long-lived one had a regular drift rate (-
  2.7 kHz/s). The type II burst was associated with a halo CME observed
  by SOHO/LASCO moving with a speed of 1120 km/s. The presence of two
  type II bursts seems to be due to the interaction of the halo CME
  with a proceeding CME, as indicated by SOHO and STEREO coronagrpahic
  images. Analysis of the scale heights based on coronal density
  variations confirms the interaction. We establish the connection
  between CME height and the frequency of the type II bursts. The CME
  was also associated with solar energetic particles, consistent with
  the strong shock. The Earth arrival of the CME-driven shock was also
  observed by Wind/TNR and SoHO/CELIAS Proton Monitor.

---------------------------------------------------------
Title: Understanding the Longitudinal Extent and Timing of SEP Onsets:
    The November 3 2011 Event
Authors: Xie, Hong; St. Cyr, C.; Gopalswamy, N.
2014shin.confE..86X    Altcode:
  We study a multi-spacecraft solar energetic particle (SEP) event,
  which occurred on November 3 2011. The CME associated with the
  SEP event was observed as a behind the east-limb event (N06E152)
  by SOHO/LASCO. The CME was observed to be at W102 and E50 in
  STEREO-A and B views, respectively. This SEP event had a remarkable
  prompt particle increase at all three spacecraft despite their
  wide separation. Using a forward-fitting technique with an oblate
  spheroid model, we study the evolution of the CME shock and EUV wave
  in the low corona. Observations from STEREO and SOHO (white light),
  and SDO (EUV) were used to constraint the 3D shock shape and the EUV
  imprints on the solar surface. The combination of a full 3D model and
  multi-wavelength observational constraints allowed us to determine
  the radial and expansion speeds of the CME-shock and EUV wave in a
  consistent way. We were also able to determine the timing and the
  locations where the shock front intersects the magnetic footpoints
  connected to each spacecraft. The Parker-spiral theory with the average
  solar-wind speed measured in situ was used to estimate the location
  of magnetic field lines connecting the Sun to each spacecraft. The
  SEP onset time was determined by carrying out a velocity-dispersion
  analysis on the particles arriving at each spacecraft. By comparing
  the SEP onset delay with the time taken for the shock to expand to
  the longitudes of the connecting magnetic field lines, we confirmed
  that the wide spread SEP event was in fact a result of the expanding
  shock and the EUV wave for this case.

---------------------------------------------------------
Title: Estimating the Height of CMEs at the Onset of Metric Type
    II Bursts
Authors: Makela, Pertti; Gopalswamy, Nat
2014shin.confE.103M    Altcode:
  The onset of type II radio bursts indicates the moment when a shock
  front ahead of a coronal mass ejection (CME) forms and starts to
  accelerate electrons in the solar corona. Therefore, the onset of metric
  type II bursts, which can be observed remotely by radio instruments,
  provides us the first indication of the CME-driven shock front
  propagating in the solar corona. Several methods have been suggested
  to estimate the height of the associated CME. Here we estimate the
  CME height by assuming that CMEs with an initial height of 1.25 Rs
  accelerate from rest to final speed (the measured linear speed of the
  CME) during a period starting at the flare onset time and ending at the
  flare peak time, after which they propagate with a final speed. Using
  this method Gopalswamy et al. (2012) found the CME height at metric
  type II burst onset with mean and median values of 1.53 Rs and 1.47 Rs,
  respectively for the cycle 23 ground level enhancement (GLE) events. We
  have expanded this study to include all major non-GLE solar energetic
  particle (SEP) events. We find that the average and median height of
  non-GLE CMEs at the onset of the metric type II bursts to be 1.73 Rs
  and 1.61 Rs, respectively. For cycle 23 (cycle 24) CMEs the average
  height is 1.78 Rs (1.59 Rs) and the median height 1.61 Rs (1.45 Rs),
  respectively. Because Alfven speed is proportional to magnetic field,
  weaker solar magnetic fields during cycle 24 result in lower Alfven
  speeds on average and hence shocks could form earlier, if we assume
  that CME speed distributions are similar in cycle 23 and cycle 24.

---------------------------------------------------------
Title: Are Polar-crown Coronal Mass Ejections Similar to the
    Low-latitude Counterparts?
Authors: Gopalswamy, N.; Yashiro, Seiji; Akiyama, Sachiko
2014AAS...22430306G    Altcode:
  Coronal mass ejections (CMEs) from the polar-crown filament
  region originate above 60-degree latitude during solar activity
  maxima. Polar-crown CMEs originate from bipolar magnetic regions,
  whereas both bipolar and multipolar regions produce CMEs at low
  latitudes. If polar CMEs are similar to the low-latitude ones,
  then a single eruption mechanism can apply to all CMEs, the common
  element being the magnetic free energy. We examine several polar-crown
  CMEs to determine their three-part morphology, acceleration profile
  including the height of peak acceleration, CME-flare relationship,
  and energetics. We found that these properties are similar to those of
  low-latitude CMEs. We use illustrative examples from the Solar Dynamics
  Observatory images to show quantitatively that the polar-crown CMEs
  are very similar to their low-latitude counterparts. Even though the
  post eruption arcades are weak, we show that the peak thermal energy of
  these arcades is a few percent of the CME kinetic energy, similar to
  what is observed in large eruptive events. These observations suggest
  that a bipolar configuration is sufficient for the production of CMEs.

---------------------------------------------------------
Title: Latitudinal Connectivity of Ground Level Enhancement Events
Authors: Gopalswamy, N.; Mäkelä, P.
2014ASPC..484...63G    Altcode: 2013arXiv1310.8506G
  We examined the source regions and coronal environment of the historical
  ground level enhancement (GLE) events in search of evidence for
  non-radial motion of the associated coronal mass ejection (CME). For
  the 13 GLE events that had source latitudes &gt;30° we found evidence
  for possible non-radial CME motion due to deflection by large-scale
  magnetic structures in nearby coronal holes, streamers, or pseudo
  streamers. Polar coronal holes are the main source of deflection in
  the rise and declining phases of solar cycles. In the maximum phase,
  deflection by large-scale streamers or pseudo streamers overlying
  high-latitude filaments seems to be important. The B0 angle reduced
  the ecliptic distance of some GLE source regions and increased in
  others with the net result that the average latitude of GLE events did
  not change significantly. The non-radial CME motion is the dominant
  factor that reduces the ecliptic distance of GLE source regions,
  thereby improving the latitudinal connectivity to Earth. We further
  infer that the GLE particles must be accelerated at the nose part of
  the CME-driven shocks, where the shock is likely to be quasi-parallel.

---------------------------------------------------------
Title: Anomalous expansion of coronal mass ejections during solar
    cycle 24 and its space weather implications
Authors: Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Xie,
   Hong; Mäkelä, Pertti; Michalek, Grzegorz
2014GeoRL..41.2673G    Altcode: 2014arXiv1404.0252G
  The familiar correlation between the speed and angular width of
  coronal mass ejections (CMEs) is also found in solar cycle 24, but
  the regression line has a larger slope: for a given CME speed, cycle
  24 CMEs are significantly wider than those in cycle 23. The slope
  change indicates a significant change in the physical state of the
  heliosphere, due to the weak solar activity. The total pressure in the
  heliosphere (magnetic + plasma) is reduced by ~40%, which leads to the
  anomalous expansion of CMEs explaining the increased slope. The excess
  CME expansion contributes to the diminished effectiveness of CMEs in
  producing magnetic storms during cycle 24, both because the magnetic
  content of the CMEs is diluted and also because of the weaker ambient
  fields. The reduced magnetic field in the heliosphere may contribute
  to the lack of solar energetic particles accelerated to very high
  energies during this cycle.

---------------------------------------------------------
Title: Do Solar Coronal Holes Affect the Properties of Solar Energetic
    Particle Events?
Authors: Kahler, S. W.; Arge, C. N.; Akiyama, S.; Gopalswamy, N.
2014SoPh..289..657K    Altcode:
  The intensities and timescales of gradual solar energetic particle
  (SEP) events at 1 AU may depend not only on the characteristics of
  shocks driven by coronal mass ejections (CMEs), but also on large-scale
  coronal and interplanetary structures. It has long been suspected
  that the presence of coronal holes (CHs) near the CMEs or near the
  1-AU magnetic footpoints may be an important factor in SEP events. We
  used a group of 41 E≈ 20 MeV SEP events with origins near the solar
  central meridian to search for such effects. First we investigated
  whether the presence of a CH directly between the sources of the CME
  and of the magnetic connection at 1 AU is an important factor. Then we
  searched for variations of the SEP events among different solar wind
  (SW) stream types: slow, fast, and transient. Finally, we considered the
  separations between CME sources and CH footpoint connections from 1 AU
  determined from four-day forecast maps based on Mount Wilson Observatory
  and the National Solar Observatory synoptic magnetic-field maps and
  the Wang-Sheeley-Arge model of SW propagation. The observed in-situ
  magnetic-field polarities and SW speeds at SEP event onsets tested the
  forecast accuracies employed to select the best SEP/CH connection events
  for that analysis. Within our limited sample and the three analytical
  treatments, we found no statistical evidence for an effect of CHs on SEP
  event peak intensities, onset times, or rise times. The only exception
  is a possible enhancement of SEP peak intensities in magnetic clouds.

---------------------------------------------------------
Title: Multiwavelength diagnostics of the precursor and main phases
    of an M1.8 flare on 2011 April 22
Authors: Awasthi, A. K.; Jain, R.; Gadhiya, P. D.; Aschwanden, M. J.;
   Uddin, W.; Srivastava, A. K.; Chandra, R.; Gopalswamy, N.; Nitta,
   N. V.; Yashiro, S.; Manoharan, P. K.; Choudhary, D. P.; Joshi, N. C.;
   Dwivedi, V. C.; Mahalakshmi, K.
2014MNRAS.437.2249A    Altcode: 2013arXiv1310.6029A; 2013MNRAS.tmp.2720A
  We study the temporal, spatial and spectral evolution of the M1.8 flare,
  which occurred in the active region 11195 (S17E31) on 2011 April 22,
  and explore the underlying physical processes during the precursor
  phase and their relation to the main phase. The study of the source
  morphology using the composite images in 131 Å wavelength observed by
  the Solar Dynamics Observatory/Atmospheric Imaging Assembly and 6-14
  keV [from the Reuven Ramaty High Energy Solar Spectroscopic Imager
  (RHESSI)] revealed a multiloop system that destabilized systematically
  during the precursor and main phases. In contrast, hard X-ray emission
  (20-50 keV) was absent during the precursor phase, appearing only from
  the onset of the impulsive phase in the form of foot-points of emitting
  loops. This study also revealed the heated loop-top prior to the loop
  emission, although no accompanying foot-point sources were observed
  during the precursor phase. We estimate the flare plasma parameters,
  namely temperature (T), emission measure (EM), power-law index (γ)
  and photon turn-over energy (ɛ<SUB>to</SUB>), and found them to be
  varying in the ranges 12.4-23.4 MK, 0.0003-0.6 × 10<SUP>49</SUP>
  cm<SUP>-3</SUP>, 5-9 and 14-18 keV, respectively, by forward fitting
  RHESSI spectral observations. The energy released in the precursor
  phase was thermal and constituted ≈1 per cent of the total energy
  released during the flare. The study of morphological evolution of
  the filament in conjunction with synthesized T and EM maps was carried
  out, which reveals (a) partial filament eruption prior to the onset of
  the precursor emission and (b) heated dense plasma over the polarity
  inversion line and in the vicinity of the slowly rising filament during
  the precursor phase. Based on the implications from multiwavelength
  observations, we propose a scheme to unify the energy release during
  the precursor and main phase emissions in which the precursor phase
  emission was originated via conduction front that resulted due to the
  partial filament eruption. Next, the heated leftover S-shaped filament
  underwent slow-rise and heating due to magnetic reconnection and finally
  erupted to produce emission during the impulsive and gradual phases.

---------------------------------------------------------
Title: INSTANT: INvestigation of Solar-Terrestrial Associated
    Natural Threats
Authors: Lavraud, Benoit; Vial, Jean-Claude; Harrison, Richard; Davies,
   Jackie; Escoubet, C. Philippe; Zong, Qiugang; Auchere, Frederic; Liu,
   Ying; Bale, Stuart; Gopalswamy, Nat; Li, Gang; Maksimovic, Milan;
   Liu, William; Rouillard, Alexis
2014cosp...40E1758L    Altcode:
  The INSTANT mission will tackle both compelling solar and heliospheric
  science objectives and novel space weather capabilities. This is
  allowed by combining innovative and state-of-the-art instrumentation
  at an appropriate off-Sun-Earth line location on an orbit lagging
  the Earth around the Sun, near the L5 Lagrangian point. It is an
  affordable mission that tackles major objectives of the European and
  Chinese communities in terms of space physics and space weather. The
  science objectives are: 1. What is the magnetic field magnitude and
  topology in the corona? 2. How does the magnetic field reconfigure
  itself during CME eruptions? 3. What are the sources and links between
  the slow and fast winds? 4. How do CMEs accelerate and interact in the
  interplanetary medium? The mission will further allow the following
  crucial space weather capabilities: 5. Three-days advance knowledge
  of CIR properties that reach Earth. 6. Twelve hours to 2 days advance
  warning of Earth-directed CMEs. 7. Thanks to Lyman-α observations,
  first-ever capability of determining the magnetic field magnitude and
  orientation of Earth-directed CMEs. The mission will be proposed in
  the context of the upcoming ESA-China S-class call for mission.

---------------------------------------------------------
Title: Flare - Flux Rope Relationship using Post-eruption Arcades
Authors: Gopalswamy, Nat; Xie, Hong; Yashiro, Seiji; Akiyama, Sachiko
2014cosp...40E1047G    Altcode:
  A close connection between the coronal mass ejections (CME) and flare
  in a given solar eruption has been confirmed from various aspects
  of the two phenomena. The relation between the reconnection flux and
  the poloidal flux of the associated 1-AU flux ropes is of particular
  importance because it can be used for space weather predictions. It is
  customary to compute the flare reconnection flux from the flare-ribbon
  area and photospheric/chromospheric magnetic field strength. Here
  we report on a new method to compute the reconnection flux from
  post-eruption arcades (PEAs). Instead of counting the ribbon pixels in a
  series of images, we simply measure the area under PEAs after the flare
  maximum and the underlying photospheric magnetic field. The reconnection
  flux is then half of the product of these two quantities. We illustrate
  this method using specific examples and show that the ribbon and
  arcade methods yield results, which are in good agreement. Finally,
  we show that this provides a simple means of predicting the 1-AU flux
  rope magnetic field from measurements made near the Sun.

---------------------------------------------------------
Title: Future L5 Missions for Solar Physics and Space Weather
Authors: Auchere, Frederic; Gopalswamy, Nat
2014cosp...40E.148A    Altcode:
  Coronal mass ejections (CMEs) and corotating interaction regions (CIR)
  are the sources of intense space weather in the heliosphere. Most of
  the current knowledge on CMEs accumulated over the past few decades
  has been derived from observations made from the Sun-Earth line,
  which is not the ideal vantage point to observe Earth-affecting
  CMEs (Gopalswamy et al., 2011a,b). In this paper, the advantages of
  remote-sensing and in-situ observations from the Sun-Earth L5 point
  are discussed. Locating a mission at Sun-Earth L5 has several key
  benefits for solar physics and space weather: (1) off the Sun-Earth
  line view is critical in observing Earth-arriving parts of CMEs,
  (2) L5 coronagraphic observations can also provide near-Sun space
  speed of CMEs, which is an important input to models that forecast
  Earth-arrival time of CMEs, (3) backside and frontside CMEs can be
  readily distinguished even without inner coronal imagers, (4) preceding
  CMEs in the path of Earth-affecting CMEs can be identified for a better
  estimate of the travel time, (5) CIRs reach the L5 point a few days
  before they arrive at Earth, and hence provide significant lead time
  before CIR arrival, (6) L5 observations can provide advance knowledge
  of CME and CIR source regions (coronal holes) rotating to Earth view,
  and (7) magnetograms obtained from L5 can improve the surface magnetic
  field distribution used as input to MHD models that predict the
  background solar wind. The paper also discusses L5 mission concepts
  that can be achieved in the near future. References Gopalswamy, N.,
  Davila, J. M., St. Cyr, O. C., Sittler, E. C., Auchère, F., Duvall,
  T. L., Hoeksema, J. T., Maksimovic, M., MacDowall, R. J., Szabo,
  A., Collier, M. R. (2011a), Earth-Affecting Solar Causes Observatory
  (EASCO): A potential International Living with a Star Mission from
  Sun-Earth L5 JASTP 73, 658-663, DOI: 10.1016/j.jastp.2011.01.013
  Gopalswamy, N., Davila, J. M., Auchère, F., Schou, J., Korendyke,
  C. M. Shih, A., Johnston, J. C., MacDowall, R. J., Maksimovic, M.,
  Sittler, E., et al. (2011b), Earth-Affecting Solar Causes Observatory
  (EASCO): a mission at the Sun-Earth L5, Solar Physics and Space Weather
  Instrumentation IV. Ed. Fineschi, S. &amp; Fennelly, J., Proceedings
  of the SPIE, Volume 8148, article id. 81480Z, DOI: 10.1117/12.901538

---------------------------------------------------------
Title: Obscuration of Flare Emission by an Eruptive Prominence
Authors: Gopalswamy, Nat; Yashiro, Seiji
2013PASJ...65S..11G    Altcode: 2013arXiv1309.2046G
  We report on the eclipsing of microwave flare emission by an eruptive
  prominence from a neighboring region as observed by the Nobeyama
  Radioheliograph at 17 GHz. The obscuration of the flare emission
  appears as a dimming feature in the microwave flare light curve. We
  use the dimming feature to derive the temperature of the prominence
  and the distribution of heating along the length of the filament. We
  find that the prominence is heated to a temperature above the quiet Sun
  temperature at 17 GHz. The duration of the dimming is the time taken
  by the eruptive prominence in passing over the flaring region. We also
  find evidence for the obscuration in EUV images obtained by the Solar
  and Heliospheric Observatory (SOHO) mission.

---------------------------------------------------------
Title: Solar energetic particle events during the rise phases of
    solar cycles 23 and 24
Authors: Chandra, R.; Gopalswamy, N.; Mäkelä, P.; Xie, H.; Yashiro,
   S.; Akiyama, S.; Uddin, W.; Srivastava, A. K.; Joshi, N. C.; Jain,
   R.; Awasthi, A. K.; Manoharan, P. K.; Mahalakshmi, K.; Dwivedi, V. C.;
   Choudhary, D. P.; Nitta, N. V.
2013AdSpR..52.2102C    Altcode:
  We present a comparative study of the properties of coronal mass
  ejections (CMEs) and flares associated with the solar energetic particle
  (SEP) events in the rising phases of solar cycles (SC) 23 (1996-1998)
  (22 events) and 24 (2009-2011) (20 events), which are associated
  with type II radio bursts. Based on the SEP intensity, we divided the
  events into three categories, i.e. weak (intensity &lt; 1 pfu), minor
  (1 pfu &lt; intensity &lt; 10 pfu) and major (intensity ⩾ 10 pfu)
  events. We used the GOES data for the minor and major SEP events and
  SOHO/ERNE data for the weak SEP event. We examine the correlation
  of SEP intensity with flare size and CME properties. We find that
  most of the major SEP events are associated with halo or partial halo
  CMEs originating close to the sun center and western-hemisphere. The
  fraction of halo CMEs in SC 24 is larger than the SC 23. For the minor
  SEP events one event in SC23 and one event in SC24 have widths &lt;
  120° and all other events are associated with halo or partial halo
  CMEs as in the case of major SEP events. In case of weak SEP events,
  majority (more than 60%) of events are associated with CME width &lt;
  120°. For both the SC the average CMEs speeds are similar. For major
  SEP events, average CME speeds are higher in comparison to minor and
  weak events. The SEP event intensity and GOES X-ray flare size are
  poorly correlated. During the rise phase of solar cycle 23 and 24,
  we find north-south asymmetry in the SEP event source locations: in
  cycle 23 most sources are located in the south, whereas during cycle
  24 most sources are located in the north. This result is consistent
  with the asymmetry found with sunspot area and intense flares.

---------------------------------------------------------
Title: A Study of Coronal Holes Observed by SoHO/EIT and the Nobeyama
    Radioheliograph
Authors: Akiyama, Sachiko; Gopalswamy, Nat; Yashiro, Seiji; Mäkelä,
   Pertti
2013PASJ...65S..15A    Altcode:
  Coronal holes (CHs) are areas of reduced emission in EUV and X-ray
  images that show bright patches of microwave enhancements (MEs) related
  to magnetic network junctions inside the CHs. A clear correlation
  between the CH size and the solar wind (SW) speed is well known, but we
  have less information about the relationship between MEs and other CH
  and SW properties. We studied the characteristics of 21 equatorial CHs
  associated with corotating interaction regions (CIRs) during 1996 to
  2005. Our CHs were divided into two groups according to the intensity
  of the associated geomagnetic storms: Dst ≤ -100 nT (10 events) and
  &gt; -100 nT (11 events). Using EUV 284 Å images obtained by SOHO/EIT
  and 17 GHz microwave images obtained by the Nobeyama Radioheliograph
  (NoRH), we found a linear correlation not only between the maximum SW
  speed and the area of EUV CH (r = 0.62), but also between the maximum
  SW speed and the area of the ME (r = 0.79). We also compared the EUV
  CH areas with and without an overlapping ME. The area of the CHs with
  an ME is better correlated with the SW speed (r = 0.71) than the area
  of those without an ME (r = 0.36). Therefore, the radio ME may play
  an important role in understanding the origin of SW.

---------------------------------------------------------
Title: Testing the empirical shock arrival model using quadrature
    observations
Authors: Gopalswamy, N.; Mäkelä, P.; Xie, H.; Yashiro, S.
2013SpWea..11..661G    Altcode: 2013arXiv1310.8510G
  The empirical shock arrival (ESA) model was developed based on
  quadrature data from Helios (in situ) and P-78 (remote sensing)
  to predict the Sun-Earth travel time of coronal mass ejections
  (CMEs). The ESA model requires earthward CME speed as input, which
  is not directly measurable from coronagraphs along the Sun-Earth
  line. The Solar Terrestrial Relations Observatory (STEREO) and the
  Solar and Heliospheric Observatory (SOHO) were in quadrature during
  2010-2012, so the speeds of Earth-directed CMEs were observed with
  minimal projection effects. We identified a set of 20 full halo CMEs
  in the field of view of SOHO that were also observed in quadrature
  by STEREO. We used the earthward speed from STEREO measurements as
  input to the ESA model and compared the resulting travel times with the
  observed ones from L1 monitors. We find that the model predicts the CME
  travel time within about 7.3 h, which is similar to the predictions
  by the ENLIL model. We also find that CME-CME and CME-coronal hole
  interaction can lead to large deviations from model predictions.

---------------------------------------------------------
Title: Flux emergence, flux imbalance, magnetic free energy and
    solar flares
Authors: Choudhary, Debi Prasad; Gosain, Sanjay; Gopalswamy, Nat;
   Manoharan, P. K.; Chandra, R.; Uddin, W.; Srivastava, A. K.; Yashiro,
   S.; Joshi, N. C.; Kayshap, P.; Dwivedi, V. C.; Mahalakshmi, K.;
   Elamathi, E.; Norris, Max; Awasthi, A. K.; Jain, R.
2013AdSpR..52.1561C    Altcode:
  Emergence of complex magnetic flux in the solar active regions lead
  to several observational effects such as a change in sunspot area
  and flux embalance in photospheric magnetograms. The flux emergence
  also results in twisted magnetic field lines that add to free energy
  content. The magnetic field configuration of these active regions
  relax to near potential-field configuration after energy release
  through solar flares and coronal mass ejections. In this paper,
  we study the relation of flare productivity of active regions with
  their evolution of magnetic flux emergence, flux imbalance and free
  energy content. We use the sunspot area and number for flux emergence
  study as they contain most of the concentrated magnetic flux in the
  active region. The magnetic flux imbalance and the free energy are
  estimated using the HMI/SDO magnetograms and Virial theorem method. We
  find that the active regions that undergo large changes in sunspot
  area are most flare productive. The active regions become flary when
  the free energy content exceeds 50% of the total energy. Although,
  the flary active regions show magnetic flux imbalance, it is hard to
  predict flare activity based on this parameter alone.

---------------------------------------------------------
Title: Understanding shock dynamics in the inner heliosphere with
modeling and type II radio data: A statistical study
Authors: Xie, H.; St. Cyr, O. C.; Gopalswamy, N.; Odstrcil, D.;
   Cremades, H.
2013JGRA..118.4711X    Altcode:
  We study two methods of predicting interplanetary shock location and
  strength in the inner heliosphere: (1) the ENLIL simulation and (2)
  the kilometric type II (kmTII) prediction. To evaluate differences in
  the performance of the first method, we apply two sets of coronal mass
  ejections (CME) parameters from the cone-model fitting and flux-rope
  (FR) model fitting as input to the ENLIL model for 16 halo CMEs. The
  results show that the ENLIL model using the actual CME speeds from
  FR-fit provided an improved shock arrival time (SAT) prediction. The
  mean prediction errors for the FR and cone-model inputs are 4.90±5.92
  h and 5.48±6.11 h, respectively. A deviation of 100 km s<SUP>-1</SUP>
  from the actual CME speed has resulted in a SAT error of 3.46 h on
  average. The simulations show that the shock dynamics in the inner
  heliosphere agrees with the drag-based model. The shock acceleration
  can be divided as two phases: a faster deceleration phase within 50
  R<SUB>s</SUB> and a slower deceleration phase at distances beyond
  50 R<SUB>s</SUB>. The linear-fit deceleration in phase 1 is about 1
  order of magnitude larger than that in phase 2. When applying the
  kmTII method to 14 DH-km CMEs, we found that combining the kmTII
  method with the ENLIL outputs improved the kmTII prediction. Due to
  a better modeling of plasma density upstream of shocks and the kmTII
  location, we are able to provide a more accurate shock time-distance
  and speed profiles. The mean kmTII prediction error using the ENLIL
  model density is 6.7±6.4 h; it is 8.4±10.4 h when the average solar
  wind plasma density is used. Applying the ENLIL density has reduced the
  mean kmTII prediction error by ∼2 h and the standard deviation by 4.0
  h. Especially when we applied the combined approach to two interacting
  events, the kmTII prediction error was drastically reduced from 29.6 h
  to -4.9 h in one case and 10.6 h to 4.2 h in the other. Furthermore,
  the results derived from the kmTII method and the ENLIL simulation,
  together with white-light data, provide a valuable validation of
  shock formation location and strength. Such information has important
  implications for solar energetic particle acceleration.

---------------------------------------------------------
Title: A multiwavelength study of eruptive events on January 23,
    2012 associated with a major solar energetic particle event
Authors: Joshi, N. C.; Uddin, W.; Srivastava, A. K.; Chandra, R.;
   Gopalswamy, N.; Manoharan, P. K.; Aschwanden, M. J.; Choudhary, D. P.;
   Jain, R.; Nitta, N. V.; Xie, H.; Yashiro, S.; Akiyama, S.; Mäkelä,
   P.; Kayshap, P.; Awasthi, A. K.; Dwivedi, V. C.; Mahalakshmi, K.
2013AdSpR..52....1J    Altcode: 2013arXiv1303.1251J
  We use multiwavelength data from space and ground based instruments
  to study the solar flares and coronal mass ejections (CMEs) on January
  23, 2012 that were responsible for one of the largest solar energetic
  particle (SEP) events of solar cycle 24. The eruptions consisting of two
  fast CMEs (≈1400 km s<SUP>-1</SUP> and ≈2000 km s<SUP>-1</SUP>) and
  M-class flares that occurred in active region 11402 located at ≈N28
  W36. The two CMEs occurred in quick successions, so they interacted
  very close to the Sun. The second CME caught up with the first one
  at a distance of ≈11-12 R<SUB>sun</SUB>. The CME interaction may be
  responsible for the elevated SEP flux and significant changes in the
  intensity profile of the SEP event. The compound CME resulted in a
  double-dip moderate geomagnetic storm (Dst∼-73nT). The two dips are
  due to the southward component of the interplanetary magnetic field in
  the shock sheath and the ICME intervals. One possible reason for the
  lack of a stronger geomagnetic storm may be that the ICME delivered
  a glancing blow to Earth.

---------------------------------------------------------
Title: An Automatic Detection Technique for Prominence Eruptions
    and Surges using SDO/AIA Images
Authors: Yashiro, Seiji; Gopalswamy, N.; Makela, P.; Akiyama, S.;
   Sterling, A. C.
2013SPD....44...99Y    Altcode:
  We present an automatic technique to detect and characterize eruptive
  events (EEs), e.g. prominence eruptions and surges, using SDO/AIA
  304 Å images. The technique works as follows. 1) The SDO 304 Å
  images are polar-transformed for easy handling of the outward motion
  of EEs and for saving computer resources. 2) The transformed images
  are divided by a background map, which is determined as the minimum
  intensity of each pixel during 24 hours. 3) The EEs are defined as a
  region in the ratio maps with pixels having a ratio &gt;2. Because a
  stationary prominence has relatively high background, the prominence
  is detected only when it moves. 4) Pattern recognition is performed to
  separate different EEs at different locations. 5) In successive images,
  two EEs with more than 50% of pixels overlapping are considered to
  be the same EE. 6) If the height of an EE increases monotonically
  in 5 successive images, we consider it as a reliable eruption. The
  technique detects 1428 prominence eruptions and 1921 surges from 2010
  May to 2012 December. The locations of PEs identified by this technique
  clearly indicated decayed onset of the maximum phase in the south with
  respect to the north. This work was supported by NASA Living with a
  Star TR&amp;T programAbstract (2,250 Maximum Characters): We present
  an automatic technique to detect and characterize eruptive events
  (EEs), e.g. prominence eruptions and surges, using SDO/AIA 304 Å
  images. The technique works as follows. 1) The SDO 304 Å images are
  polar-transformed for easy handling of the outward motion of EEs and
  for saving computer resources. 2) The transformed images are divided by
  a background map, which is determined as the minimum intensity of each
  pixel during 24 hours. 3) The EEs are defined as a region in the ratio
  maps with pixels having a ratio &gt;2. Because a stationary prominence
  has relatively high background, the prominence is detected only when it
  moves. 4) Pattern recognition is performed to separate different EEs at
  different locations. 5) In successive images, two EEs with more than 50%
  of pixels overlapping are considered to be the same EE. 6) If the height
  of an EE increases monotonically in 5 successive images, we consider it
  as a reliable eruption. The technique detects 1428 prominence eruptions
  and 1921 surges from 2010 May to 2012 December. The locations of PEs
  identified by this technique clearly indicated decayed onset of the
  maximum phase in the south with respect to the north. This work was
  supported by NASA Living with a Star TR&amp;T program

---------------------------------------------------------
Title: Solar Sources of Wide Coronal Mass Ejections during the
    Ascending Phase of Cycle 24
Authors: Akiyama, Sachiko; Gopalswamy, N.; Yashiro, S.; Makela, P.
2013SPD....44..130A    Altcode:
  It is well known that fast and wide CMEs are generally involved in large
  solar energetic particle (SEP) events and are generally important in
  affecting the heliosphere. We examined the solar sources of all wide
  CMEs (width ≥ 60°) observed by SOHO/LASCO and STEREO/SECCHI in 2011
  (ascending phase of solar cycle 24) by confirming the back-sided events
  using STEREO data. We identified 600 wide CMEs, of which 323 (54%)
  and 163 (27%) were associated with active region flares and eruptive
  quiescent filaments, respectively. In 88 cases (15%) only EUV dimmings
  were observed. The remaining 26 (4%) CMEs were of unknown origin,
  including 7 stealth CMEs. It is significant that about 1% of all wide
  CMEs do not have identifiable near-surface signatures. Considering only
  the front side CMEs, the median X-ray intensity associated with ARs and
  filament regions were C3.7 and C1.6, respectively. The average speeds of
  AR and quiescent-filament CMEs were, 537 and 373 km/s. We conclude that
  some the results of the previous solar cycles can be clarified because
  of the availability of STEREO data.Abstract (2,250 Maximum Characters):
  It is well known that fast and wide CMEs are generally involved in large
  solar energetic particle (SEP) events and are generally important in
  affecting the heliosphere. We examined the solar sources of all wide
  CMEs (width ≥ 60°) observed by SOHO/LASCO and STEREO/SECCHI in 2011
  (ascending phase of solar cycle 24) by confirming the back-sided events
  using STEREO data. We identified 600 wide CMEs, of which 323 (54%)
  and 163 (27%) were associated with active region flares and eruptive
  quiescent filaments, respectively. In 88 cases (15%) only EUV dimmings
  were observed. The remaining 26 (4%) CMEs were of unknown origin,
  including 7 stealth CMEs. It is significant that about 1% of all wide
  CMEs do not have identifiable near-surface signatures. Considering
  only the front side CMEs, the median X-ray intensity associated with
  ARs and filament regions were C3.7 and C1.6, respectively. The average
  speeds of AR and quiescent-filament CMEs were, 537 and 373 km/s. We
  conclude that some the results of the previous solar cycles can be
  clarified because of the availability of STEREO data.

---------------------------------------------------------
Title: On the Solar Sources of Polar-crown Coronal Mass Ejections
Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.
2013SPD....44...83G    Altcode:
  Coronal mass ejections (CMEs) from the polar crown filament
  region originate above 60-degree latitude during solar activity
  maxima. Cessation of these high-latitude CMEs marks the end of the
  maximum phase when the solar poles reverse their polarity. The eruption
  mechanism of these polar CMEs is not well understood: they originate
  from bipolar magnetic regions in contrast to the low-latitude ones,
  which may occur from both bipolar and multipolar regions. One of the
  key questions is whether the polar CMEs are associated with flare-like
  brightening and if so what the nature of the CME-flare relationship
  is. We investigated a number of polar CMEs, which do have post-eruption
  arcades (PEAs) observed in soft X-ray and EUV wavelengths. We combine
  data from the Solar Dynamics Observatory (SDO), the Solar Terrestrial
  Relations Observatory (STEREO), and the Solar Heliospheric Observatory
  (SOHO) to examine the flare-CME relationship in the case of polar
  crown CMEs. In particular, we measure the initial CME acceleration and
  compare it with the time-derivative of the PEA intensity to demonstrate
  a relationship akin to Neupert effect. The CME morphology, mass,
  and kinematics are similar to the low-latitude CMEs. The ratio of the
  thermal energy content of PEAs to the CME kinetic energy is very similar
  to that from low-latitude CMEs. Finally, the free energy estimated from
  photospheric magnetograms and the area covered by the PEAs, we find
  that the free energy is sufficient to power the CMEs and PEAs. Thus,
  we conclude that the polar-crown CMEs are fundamentally similar to
  the low-latitude CMEs and hence may have similar eruption mechanism.

---------------------------------------------------------
Title: Connecting Near-Sun CME flux Ropes to the 1-AU Flux Ropes
    using the Flare-CME Relationship
Authors: Gopalswamy, N.; Xie, H.; Yashiro, S.; Akiyama, S.
2013SPD....4430001G    Altcode:
  Coronal mass ejections (CMEs) and solar flares are closely related in
  various ways because the two phenomena are different manifestations
  of the same energy release in closed magnetic regions on the sun. Of
  particular interest is the relation between flare reconnection flux
  at the Sun and the poloidal flux of the 1-AU flux rope associated
  with the flare. If a flux rope forms due to flare reconnection,
  then the two fluxes are almost equal. The flare reconnection flux
  is normally computed from the flare-ribbon area and the photospheric
  field strength in the ribbon area. Here we report on another technique,
  which makes use of the area under the post-eruption arcade (PEA). We
  show that the reconnection flux derived from the PEA technique agrees
  with the one derived from flare ribbons. We also fit a flux rope to the
  white-light CME observations and derive the aspect ratio of the flux
  rope. Assuming self-similar expansion of the flux rope, we show that
  the magnetic content and size of the 1-AU flux rope can be predicted
  from the flare magnetic field (the average photospheric field strength
  within half of the PEA area) and the aspect ratio of the coronal flux
  rope. We illustrate the method with several examples.

---------------------------------------------------------
Title: Effect of CME interactions on SEP intensity: modeling the
    2012-March-07 SEP event with ENLIL
Authors: Xie, Hong; Gopalswamy, N.; St. Cyr, O. C.
2013SPD....44..125X    Altcode:
  We performed a case study on the effect of CME interactions on SEP
  intensity for the 2012-March-07 SEP event. The 2012 March 07 SEP event
  had the second largest intensity during solar cycle 24. The SEP/ESP peak
  intensities peaked at 1500/6000 pfu. The event was associated with a
  double X-ray flare and two CMEs in quick succession. In soft X-rays,
  the flares reached peak flux levels of X5.4 (00:02 UT) and X1.1,
  respectively, from AR1429 (N18E31). The flare peaks were at ~00:24
  and ~01:14 UT, while the onset times were 00:02 UT and 01:05 UT. The
  associated CMEs were very fast: 2376 km/s (CME1) and 2203 km/s (CME2)
  and appeared &lt; 1 hour apart. Two distinct type II radio bursts were
  detected in the decameter-hectometric (DH) spectrum observed by the
  Wind/WAVES experiment. The interaction of two CMEs was clearly seen
  from STEREO COR2 B movie from West limb around 01:54 UT, with enhanced
  signature in DH type II spectrum around the same time. The two CMEs
  arrived at 21.5 Rs (inner boundary of ENLIL) at 01:55 UT and 02:40 UT,
  respectively, with flux-rope fitted propagation directions of N17E27
  and N00E17. Two ENLIL runs were performed: 1) only CME1 was inserted
  at 21.5Rs and 2) both CME1 and CME2 were inserted in the simulation to
  study the effect of CME interactions. Comparing the results of the two
  runs, we found that both the shock intensity and shock speed of Run2
  were higher than Run1, suggesting that the CME interaction have not
  only enhanced shock intensity but also caused higher speed, therefore
  resulting in larger SEP intensity. This work was supported by NASA
  Living with a Star TR&amp;T programAbstract (2,250 Maximum Characters):
  We performed a case study on the effect of CME interactions on SEP
  intensity for the 2012-March-07 SEP event. The 2012 March 07 SEP event
  had the second largest intensity during solar cycle 24. The SEP/ESP peak
  intensities peaked at 1500/6000 pfu. The event was associated with a
  double X-ray flare and two CMEs in quick succession. In soft X-rays,
  the flares reached peak flux levels of X5.4 (00:02 UT) and X1.1,
  respectively, from AR1429 (N18E31). The flare peaks were at ~00:24
  and ~01:14 UT, while the onset times were 00:02 UT and 01:05 UT. The
  associated CMEs were very fast: 2376 km/s (CME1) and 2203 km/s (CME2)
  and appeared &lt; 1 hour apart. Two distinct type II radio bursts were
  detected in the decameter-hectometric (DH) spectrum observed by the
  Wind/WAVES experiment. The interaction of two CMEs was clearly seen
  from STEREO COR2 B movie from West limb around 01:54 UT, with enhanced
  signature in DH type II spectrum around the same time. The two CMEs
  arrived at 21.5 Rs (inner boundary of ENLIL) at 01:55 UT and 02:40 UT,
  respectively, with flux-rope fitted propagation directions of N17E27
  and N00E17. Two ENLIL runs were performed: 1) only CME1 was inserted
  at 21.5Rs and 2) both CME1 and CME2 were inserted in the simulation
  to study the effect of CME interactions. Comparing the results of
  the two runs, we found that both the shock intensity and shock speed
  of Run2 were higher than Run1, suggesting that the CME interaction
  have not only enhanced shock intensity but also caused higher speed,
  therefore resulting in larger SEP intensity. This work was supported
  by NASA Living with a Star TR&amp;T program

---------------------------------------------------------
Title: Observations of CMEs and models of the eruptive corona
Authors: Gopalswamy, Nat
2013AIPC.1539....5G    Altcode: 2013arXiv1304.0087G
  Current theoretical ideas on the internal structure of CMEs
  suggest that a flux rope is central to the CME structure, which
  has considerable observational support both from remote-sensing and
  in-situ observations. The flux-rope nature is also consistent with the
  post-eruption arcades with high-temperature plasmas and the charge
  states observed within CMEs arriving at Earth. The model involving
  magnetic loop expansion to explain CMEs without flux ropes is not
  viable because it contradicts CME kinematics and flare properties
  near the Sun. The flux rope is fast, it drives a shock, so the global
  picture of CMEs becomes complete if one includes the shock sheath to
  the CSHKP model.

---------------------------------------------------------
Title: Height of shock formation in the solar corona inferred from
    observations of type II radio bursts and coronal mass ejections
Authors: Gopalswamy, N.; Xie, H.; Mäkelä, P.; Yashiro, S.; Akiyama,
   S.; Uddin, W.; Srivastava, A. K.; Joshi, N. C.; Chandra, R.; Manoharan,
   P. K.; Mahalakshmi, K.; Dwivedi, V. C.; Jain, R.; Awasthi, A. K.;
   Nitta, N. V.; Aschwanden, M. J.; Choudhary, D. P.
2013AdSpR..51.1981G    Altcode: 2013arXiv1301.0893G
  Employing coronagraphic and EUV observations close to the solar surface
  made by the Solar Terrestrial Relations Observatory (STEREO) mission,
  we determined the heliocentric distance of coronal mass ejections
  (CMEs) at the starting time of associated metric type II bursts. We
  used the wave diameter and leading edge methods and measured the CME
  heights for a set of 32 metric type II bursts from solar cycle 24. We
  minimized the projection effects by making the measurements from a
  view that is roughly orthogonal to the direction of the ejection. We
  also chose image frames close to the onset times of the type II bursts,
  so no extrapolation was necessary. We found that the CMEs were located
  in the heliocentric distance range from 1.20 to 1.93 solar radii (Rs),
  with mean and median values of 1.43 and 1.38 Rs, respectively. We
  conclusively find that the shock formation can occur at heights
  substantially below 1.5 Rs. In a few cases, the CME height at type
  II onset was close to 2 Rs. In these cases, the starting frequency
  of the type II bursts was very low, in the range 25-40 MHz, which
  confirms that the shock can also form at larger heights. The starting
  frequencies of metric type II bursts have a weak correlation with the
  measured CME/shock heights and are consistent with the rapid decline
  of density with height in the inner corona.

---------------------------------------------------------
Title: Observations of the Highest Energy Particles from the Sun
    and the Identification of their Acceleration Mechanism
Authors: Gopalswamy, Nat; Xie, H.; Yashiro, S.
2013shin.confE.142G    Altcode:
  The highest energy ( GeV) particles accelerated by the Sun are the
  Ground Level Enhancement (GLE) in solar energetic particle (SEP) events
  during large solar eruptions. Extensive observations of GLE-associated
  coronal mass ejections (CMEs) during solar cycle 23 suggest that shocks
  forming very close to the Sun have sufficient time to accelerate GeV
  particles. The first GLE event of solar cycle 24 (on May 17, 2012)
  is consistent with the shock acceleration mechanism because the CME
  was very fast ( 2000 km/s), but the associated flare was rather weak
  (M-class flare). Gopalswamy et al. (2013, ApJ 765, L30) showed that
  the unfavorable B0 angle and non-radial motion of CMEs might have
  rendered the shock nose poorly connected to Earth in other similar
  or larger eruptions during solar cycle 24. In such non-GLE events,
  the latitudinal distance of the source region to the ecliptic was
  much larger than that in cycle-23 GLE events. In one case, even though
  the connectivity was not an issue, the shock seemed to be rather weak
  probably because of a higher Alfven speed in the ambient medium. Thus,
  GLE events require special conditions in terms of CME kinematics,
  coronal environment, and the magnetic connectivity of the solar source
  to an Earth observer. In this work, we examined the source locations
  of historical GLE events and found that the apparent higher-latitude
  GLE events indeed have favorable B0 angle and coronal-hole deflection
  toward the equator. We also examined additional large eruptions of
  cycle 24 and confirmed the importance of connectivity to Earth.

---------------------------------------------------------
Title: Near-Sun Flux-Rope Structure of CMEs
Authors: Xie, H.; Gopalswamy, N.; St. Cyr, O. C.
2013SoPh..284...47X    Altcode: 2012arXiv1212.1409X
  We have used the Krall flux-rope model (Krall and St. Cyr,
  Astrophys. J.2006, 657, 1740) (KFR) to fit 23 magnetic cloud (MC)-CMEs
  and 30 non-cloud ejecta (EJ)-CMEs in the Living With a Star (LWS)
  Coordinated Data Analysis Workshop (CDAW) 2011 list. The KFR-fit
  results shows that the CMEs associated with MCs (EJs) have been
  deflected closer to (away from) the solar disk center (DC), likely by
  both the intrinsic magnetic structures inside an active region (AR)
  and ambient magnetic structures (e.g. nearby ARs, coronal holes,
  and streamers, etc.). The mean absolute propagation latitudes and
  longitudes of the EJ-CMEs (18<SUP>∘</SUP>, 11<SUP>∘</SUP>) were
  larger than those of the MC-CMEs (11<SUP>∘</SUP>, 6<SUP>∘</SUP>)
  by 7<SUP>∘</SUP> and 5<SUP>∘</SUP>, respectively. Furthermore, the
  KFR-fit widths showed that the MC-CMEs are wider than the EJ-CMEs. The
  mean fitting face-on width and edge-on width of the MC-CMEs (EJ-CMEs)
  were 87 (85)<SUP>∘</SUP> and 70 (63)<SUP>∘</SUP>, respectively. The
  deflection away from DC and narrower angular widths of the EJ-CMEs
  have caused the observing spacecraft to pass over only their flanks
  and miss the central flux-rope structures. The results of this work
  support the idea that all CMEs have a flux-rope structure.

---------------------------------------------------------
Title: On the Relationship Between Metric and DH Type II Bursts
Authors: Makela, P.; Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Xie, H.
2013AGUSMSH52A..01M    Altcode:
  The metric and decameter-hectometric (DH) type II radio bursts provide
  an opportunity to remotely observe the formation and propagation of
  shocks in the solar corona and in interplanetary (IP) space. However,
  the radio spectral observations give only limited information on
  the location of the source of the type II emission, which has led to
  a long-held controversy over whether the metric type II bursts are
  due to blast waves or CME-driven shocks. For example, metric type II
  bursts are occasionally observed to be coincidental with DH type II
  bursts. In these cases it has been suggested that the DH-component
  could be associated with a CME-driven shock and the m-component with
  a blast wave or unknown source, or that the DH-component originates
  from the nose of the CME-driven shock and the m-component from the
  shock flanks. In our presentation we use coronal Alfven speed profile,
  CME kinematics, and type II drift rate characteristics to provide
  a comprehensive explanation for the observed relationship between
  coronal and IP type II bursts.

---------------------------------------------------------
Title: The Solar Connection of Enhanced Heavy Ion Charge States in
the Interplanetary Medium: Implications for the Flux-Rope Structure
    of CMEs
Authors: Gopalswamy, N.; Mäkelä, P.; Akiyama, S.; Xie, H.; Yashiro,
   S.; Reinard, A. A.
2013SoPh..284...17G    Altcode: 2012arXiv1212.0900G
  We investigated a set of 54 interplanetary coronal mass ejection
  (ICME) events whose solar sources are very close to the disk center
  (within ± 15<SUP>∘</SUP> from the central meridian). The ICMEs
  consisted of 23 magnetic-cloud (MC) events and 31 non-MC events. Our
  analyses suggest that the MC and non-MC ICMEs have more or less the
  same eruption characteristics at the Sun in terms of soft X-ray flares
  and CMEs. Both types have significant enhancements in ion charge
  states, although the non-MC structures have slightly lower levels
  of enhancement. The overall duration of charge-state enhancement is
  also considerably smaller than that in MCs as derived from solar wind
  plasma and magnetic signatures. We find very good correlation between
  the Fe and O charge-state measurements and the flare properties such
  as soft X-ray flare intensity and flare temperature for both MCs and
  non-MCs. These observations suggest that both MC and non-MC ICMEs are
  likely to have a flux-rope structure and the unfavorable observational
  geometry may be responsible for the appearance of non-MC structures
  at 1 AU. We do not find any evidence for an active region expansion
  resulting in ICMEs lacking a flux-rope structure because the mechanism
  of producing high charge states and the flux-rope structure at the
  Sun is the same for MC and non-MC events.

---------------------------------------------------------
Title: Post-Eruption Arcades and Interplanetary Coronal Mass Ejections
Authors: Yashiro, S.; Gopalswamy, N.; Mäkelä, P.; Akiyama, S.
2013SoPh..284....5Y    Altcode:
  We compare the temporal and spatial properties of posteruption arcades
  (PEAs) associated with coronal mass ejections (CMEs) at the Sun that
  end up as magnetic cloud (MC) and non-MC events in the solar wind. We
  investigate the length, width, area, tilt angle, and formation time
  of the PEAs associated with 22 MC and 29 non-MC events and we find no
  difference between the two populations. According to current ideas
  on the relation between flares and CMEs, the PEA is formed together
  with the CME flux-rope structure by magnetic reconnection. Our results
  indicate that at the Sun flux ropes form during CMEs in association with
  both MC and non-MC events; however, for non-MC events the flux-rope
  structure is not observed in the interplanetary space because of the
  geometry of the observation, i.e. the location of the spacecraft when
  the structure passes through it.

---------------------------------------------------------
Title: Preface
Authors: Gopalswamy, N.; Nieves-Chinchilla, T.; Hidalgo, M.; Zhang,
   J.; Riley, P.; van Driel-Gesztelyi, L.; Mandrini, C. H.
2013SoPh..284....1G    Altcode: 2013arXiv1304.0085G
  This Topical Issue of Solar Physics, devoted to the study of flux-rope
  structure in coronal mass ejections (CMEs), is based on two Coordinated
  Data Analysis Workshops (CDAWs) held in 2010 (20 - 23 September in Dan
  Diego, California, USA) and 2011 (September 5-9 in Alcala, Spain). The
  primary purpose of the CDAWs was to address the question: Do all CMEs
  have flux rope structure? There are 18 papers om this topical issue,
  including this preface.

---------------------------------------------------------
Title: Propagation Characteristics of CMEs Associated with Magnetic
    Clouds and Ejecta
Authors: Kim, R. -S.; Gopalswamy, N.; Cho, K. -S.; Moon, Y. -J.;
   Yashiro, S.
2013SoPh..284...77K    Altcode:
  We have investigated the characteristics of magnetic cloud (MC)
  and ejecta (EJ) associated coronal mass ejections (CMEs) based on
  the assumption that all CMEs have a flux rope structure. For this,
  we used 54 CMEs and their interplanetary counterparts (interplanetary
  CMEs: ICMEs) that constitute the list of events used by the NASA/LWS
  Coordinated Data Analysis Workshop (CDAW) on CME flux ropes. We
  considered the location, angular width, and speed as well as the
  direction parameter, D. The direction parameter quantifies the degree of
  asymmetry of the CME shape in coronagraph images, and shows how closely
  the CME propagation is directed to Earth. For the 54 CDAW events,
  we found the following properties of the CMEs: i) the average value
  of D for the 23 MCs (0.62) is larger than that for the 31 EJs (0.49),
  which indicates that the MC-associated CMEs propagate more directly
  toward the Earth than the EJ-associated CMEs; ii) comparison between
  the direction parameter and the source location shows that the majority
  of the MC-associated CMEs are ejected along the radial direction, while
  many of the EJ-associated CMEs are ejected non-radially; iii) the mean
  speed of MC-associated CMEs (946 km s<SUP>−1</SUP>) is faster than
  that of EJ-associated CMEs (771 km s<SUP>−1</SUP>). For seven very
  fast CMEs (≥ 1500 km s<SUP>−1</SUP>), all CMEs with large D (≥
  0.4) are associated with MCs and the CMEs with small D are associated
  with EJs. From the statistical analysis of CME parameters, we found
  the superiority of the direction parameter. Based on these results,
  we suggest that the CME trajectory essentially determines the observed
  ICME structure.

---------------------------------------------------------
Title: Coronal Mass Ejections and Ground Level Enhancement Events
Authors: Gopalswamy, N.
2013AGUSMSH33B..04G    Altcode:
  Ground level enhancement (GLE) in solar energetic particle (SEP)
  events represent the production of GeV particles by the Sun during
  large solar eruptions. Although the GLE events were first detected
  in 1942 and reported by Scott Forbush (1946) a few years later, the
  mechanism for the production of these high-energy particles is not fully
  understood. GLEs were attributed to solar flares from the beginning,
  but after the discovery of coronal mass ejections (CMEs) in 1971,
  the possibility of CME-driven shocks accelerating GLE particles has
  also gained importance. Extensive CME observations in association with
  GLEs became available only during solar cycle 23, enabling a fresh look
  at the importance of CME-driven shocks. This paper presents a summary
  of CME properties obtained primarily from the Solar and Heliospheric
  Observatory (SOHO), which are fully consistent with shock acceleration
  of GLE particles. During solar cycle 24, there has been only one GLE
  event (on May 17, 2012) as of this writing. This is the first GLE event
  to be fully observed by the Solar Terrestrial Relations Observatory
  (STEREO) mission, providing critical information on CME kinematics
  that helped verify the results obtained for cycle 23 GLE events. In
  particular, it is confirmed that (i) the shock forms very close to
  the solar surface (within half a solar radius) and the GLE particles
  are released ~10 minutes later, and (ii) GLE events require special
  conditions in terms of CME kinematics, coronal environment, and the
  magnetic connectivity of the solar source to an Earth observer. Forbush,
  S. E., Three Unusual Cosmic-Ray Increases Possibly Due to Charged
  Particles from the Sun, Physical Review, 70, 771, 1946

---------------------------------------------------------
Title: Comparison of Helicity Signs in Interplanetary CMEs and Their
    Solar Source Regions
Authors: Cho, K. -S.; Park, S. -H.; Marubashi, K.; Gopalswamy, N.;
   Akiyama, S.; Yashiro, S.; Kim, R. -S.; Lim, E. -K.
2013SoPh..284..105C    Altcode:
  If all coronal mass ejections (CMEs) have flux ropes, then the CMEs
  should keep their helicity signs from the Sun to the Earth according to
  the helicity conservation principle. This study presents an attempt to
  answer the question from the Coordinated Data Analysis Workshop (CDAW),
  "Do all CMEs have flux ropes?", by using a qualitative helicity sign
  comparison between interplanetary CMEs (ICMEs) and their CME source
  regions. For this, we select 34 CME-ICME pairs whose source active
  regions (ARs) have continuous SOHO/MDI magnetogram data covering
  more than 24 hr without data gap during the passage of the ARs near
  the solar disk center. The helicity signs in the ARs are determined
  by estimation of cumulative magnetic helicity injected through the
  photosphere in the entire source ARs. The helicity signs in the ICMEs
  are estimated by applying the cylinder model developed by Marubashi
  (Adv. Space. Res., 26, 55, 2000) to 16 second resolution magnetic field
  data from the MAG instrument onboard the ACE spacecraft. It is found
  that 30 out of 34 events (88 %) are helicity sign-consistent events,
  while four events (12 %) are sign-inconsistent. Through a detailed
  investigation of the source ARs of the four sign-inconsistent events,
  we find that those events can be explained by the local helicity
  sign opposite to that of the entire AR helicity (28 July 2000 ICME),
  incorrectly reported solar source region in the CDAW list (20 May 2005
  ICME), or the helicity sign of the pre-existing coronal magnetic field
  (13 October 2000 and 20 November 2003 ICMEs). We conclude that the
  helicity signs of the ICMEs are quite consistent with those of the
  injected helicities in the AR regions from where the CMEs erupted.

---------------------------------------------------------
Title: Coronal Hole Influence on the Observed Structure of
    Interplanetary CMEs
Authors: Mäkelä, P.; Gopalswamy, N.; Xie, H.; Mohamed, A. A.;
   Akiyama, S.; Yashiro, S.
2013SoPh..284...59M    Altcode: 2013arXiv1301.2176M
  We report on the coronal hole (CH) influence on the 54 magnetic
  cloud (MC) and non-MC associated coronal mass ejections (CMEs)
  selected for studies during the Coordinated Data Analysis Workshops
  (CDAWs) focusing on the question if all CMEs are flux ropes. All
  selected CMEs originated from source regions located between
  longitudes 15E - 15W. Xie, Gopalswamy, and St. Cyr (2013, Solar Phys.,
  doi:10.1007/s11207-012-0209-0) found that these MC and non-MC associated
  CMEs are on average deflected towards and away from the Sun-Earth line,
  respectively. We used a CH influence parameter (CHIP) that depends
  on the CH area, average magnetic field strength, and distance from
  the CME source region to describe the influence of all on-disk CHs
  on the erupting CME. We found that for CHIP values larger than 2.6 G
  the MC and non-MC events separate into two distinct groups where MCs
  (non-MCs) are deflected towards (away) from the disk center. Division
  into two groups was also observed when the distance to the nearest CH
  was less than 3.2×10<SUP>5</SUP> km. At CHIP values less than 2.6 G
  or at distances of the nearest CH larger than 3.2×10<SUP>5</SUP> km
  the deflection distributions of the MC and non-MCs started to overlap,
  indicating diminishing CH influence. These results give support to the
  idea that all CMEs are flux ropes, but those observed to be non-MCs
  at 1 AU could be deflected away from the Sun-Earth line by nearby CHs,
  making their flux rope structure unobservable at 1 AU.

---------------------------------------------------------
Title: The First Ground Level Enhancement Event of Solar Cycle 24:
    Direct Observation of Shock Formation and Particle Release Heights
Authors: Gopalswamy, N.; Xie, H.; Akiyama, S.; Yashiro, S.; Usoskin,
   I. G.; Davila, J. M.
2013ApJ...765L..30G    Altcode: 2013arXiv1302.1474G
  We report on the 2012 May 17 ground level enhancement (GLE) event,
  which is the first of its kind in solar cycle 24. This is the first GLE
  event to be fully observed close to the surface by the Solar Terrestrial
  Relations Observatory (STEREO) mission. We determine the coronal mass
  ejection (CME) height at the start of the associated metric type
  II radio burst (i.e., shock formation height) as 1.38 Rs (from the
  Sun center). The CME height at the time of GLE particle release was
  directly measured from a STEREO image as 2.32 Rs, which agrees well
  with the estimation from CME kinematics. These heights are consistent
  with those obtained for cycle-23 GLEs using back-extrapolation. By
  contrasting the 2012 May 17 GLE with six other non-GLE eruptions from
  well-connected regions with similar or larger flare sizes and CME
  speeds, we find that the latitudinal distance from the ecliptic is
  rather large for the non-GLE events due to a combination of non-radial
  CME motion and unfavorable solar B0 angle, making the connectivity
  to Earth poorer. We also find that the coronal environment may play
  a role in deciding the shock strength.

---------------------------------------------------------
Title: A High-frequency Type II Solar Radio Burst Associated with
    the 2011 February 13 Coronal Mass Ejection
Authors: Cho, K. -S.; Gopalswamy, N.; Kwon, R. -Y.; Kim, R. -S.;
   Yashiro, S.
2013ApJ...765..148C    Altcode:
  We examine the relationship between the high-frequency (425 MHz) type II
  radio burst and the associated white-light coronal mass ejection (CME)
  that occurred on 2011 February 13. The radio burst had a drift rate of
  2.5 MHz s<SUP>-1</SUP>, indicating a relatively high shock speed. From
  SDO/AIA observations we find that a loop-like erupting front sweeps
  across high-density coronal loops near the start time of the burst
  (17:34:17 UT). The deduced distance of shock formation (0.06 Rs)
  from the flare center and speed of the shock (1100 km s<SUP>-1</SUP>)
  using the measured density from SDO/AIA observations are comparable
  to the height (0.05 Rs, from the solar surface) and speed (700 km
  s<SUP>-1</SUP>) of the CME leading edge observed by STEREO/EUVI. We
  conclude that the type II burst originates even in the low corona
  (&lt;59 Mm or 0.08 Rs, above the solar surface) due to the fast CME
  shock passing through high-density loops.

---------------------------------------------------------
Title: Extremely Impulsive Eruption associated with an X-class Flare
    on 2012 October 23
Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.
2013enss.confE.146G    Altcode:
  Typically about 10% X-class solar flares are confined, i.e., they are
  not association with mass ejection or type II bursts in the metric and
  longer wavelengths. Failed eruptions are known to occur occasionally,
  indicating the weakness of the propelling force compared to the
  overlying restraining forces. Here we report an event on 2012 October
  23 that is closer to an eruptive event: it was associated with a metric
  type II burst, EUV disturbance (SDO, STEREO) and an extremely brief
  CME in the STEREO coronagraphic field of view. This paper presents an
  analysis of the event showing that the EUV disturbance is close to
  a blast wave, but not quite. Model fitting indicates that the speed
  falls faster than that of a blast wave indicating a quick shutoff
  of the propelling force. We also compare this event with another
  eruptive event on 2012 January 27 that had a similar flare magnitude,
  but was accompanied by a huge CME with all the usual interplanetary
  disturbances.

---------------------------------------------------------
Title: Implications of Mass and Energy Loss due to Coronal Mass
    Ejections on Magnetically Active Stars
Authors: Drake, Jeremy J.; Cohen, Ofer; Yashiro, Seiji; Gopalswamy, Nat
2013ApJ...764..170D    Altcode: 2013arXiv1302.1136D
  Analysis of a database of solar coronal mass ejections (CMEs)
  and associated flares over the period 1996-2007 finds well-behaved
  power-law relationships between the 1-8 Å flare X-ray fluence and CME
  mass and kinetic energy. We extrapolate these relationships to lower
  and higher flare energies to estimate the mass and energy loss due to
  CMEs from stellar coronae, assuming that the observed X-ray emission
  of the latter is dominated by flares with a frequency as a function
  of energy dn/dE = kE <SUP>-α</SUP>. For solar-like stars at saturated
  levels of X-ray activity, the implied losses depend fairly weakly on the
  assumed value of α and are very large: \dot{M}∼ 5× 10^{-10} M_⊙
  yr<SUP>-1</SUP> and \dot{E}∼ 0.1 L_⊙. In order to avoid such large
  energy requirements, either the relationships between CME mass and speed
  and flare energy must flatten for X-ray fluence &gt;~ 10<SUP>31</SUP>
  erg, or the flare-CME association must drop significantly below 1
  for more energetic events. If active coronae are dominated by flares,
  then the total coronal energy budget is likely to be up to an order of
  magnitude larger than the canonical 10<SUP>-3</SUP> L <SUB>bol</SUB>
  X-ray saturation threshold. This raises the question of what is the
  maximum energy a magnetic dynamo can extract from a star? For an energy
  budget of 1% of L <SUB>bol</SUB>, the CME mass loss rate is about 5
  × 10<SUP>-11</SUP> M <SUB>⊙</SUB> yr<SUP>-1</SUP>.

---------------------------------------------------------
Title: Multi-wavelength diagnostics of thermal and non-thermal
    characteristics in 22 April 2011 confined flare
Authors: Awasthi, Arun K.; Jain, Rajmal; Aschwanden, Markus J.; Uddin,
   Wahab; Srivastava, Abhishek K.; Chandra, Ramesh; Gopalswamy, Nat;
   Nitta, Nariaki; Yashiro, Seiji; Manoharan, P. K.; Prasad Choudhary,
   Debi; Joshi, N. C.; Dwivedi, Vidya Charan; Mahalakshmi, K.
2013ASInC...9...71A    Altcode:
  We study the spatial, spectral and temporal characteristics of thermal
  and non-thermal emission in an M1.8 flare, which occurred in NOAA
  AR 11195 (S17E31) on 22 April 2011. This study quantifies spatial
  and temporal correlation of thermal and non-thermal emissions in
  precursor, impulsive as well as gradual phase of energy release
  employing multi-wavelength observation from SDO, HESSI and SOXS
  missions. Based on spectral fitting analysis performed on the X-ray
  emission observed by RHESSI as well as SOXS missions in low energy
  and high energy respectively, we define that &lt;20 keV emission
  corresponds to thermal and &gt;20 keV emission to be non-thermal
  counterpart of the emission. Therefore, we construct X-ray images
  employing RHESSI observation in energy bands 6-20 and 20-100 keV
  over the time integration of 30s. We report co-spatial X-ray emission
  in various phases of emission. We also report absence of non-thermal
  counterpart in the X-ray emission in precursor phase however visible at
  the commencement of main phase. To characterize thermal and non-thermal
  signatures, we overlay the X-ray image contours on the Hα and EUV
  observations from GONG and SDO/AIA respectively. We report thermal
  emission in the precursor phase to be co-spatial to UV counterpart. In
  contrast, we report absence of emission in the EUV wavebands i.e. 1600
  and 1700 Å which, in principle, correspond to temperature minimum
  zone and photosphere during the precursor phase. This confirms the
  absence of non-thermal emission as appeared in X-ray emission during
  the precursor phase. Further, during the impulsive as well as in
  gradual phase, thermal and non-thermal emissions have been found to
  be originated from a compact source, co-spatial in nature. Analysis
  of Line of sight (LOS) magnetic field observations from SDO/HMI does
  not reveal noticeable changes in the positive and negative fluxes
  as well as magnetic-field gradient during this event. In contrast,
  Hα emission observed by GONG has revealed the filament eruption as
  the trigger of flare. This suggests filament eruption to be driver of
  this event, consistent with the CSHKP model of solar flare.

---------------------------------------------------------
Title: STEREO and SOHO contributions to coronal mass ejection studies:
    Some recent results
Authors: Gopalswamy, N.
2013ASInC..10...11G    Altcode:
  This paper summarizes some recent results on coronal mass ejections
  (CMEs) obtained from the Solar Terrestrial Relations Observatory
  (STEREO) that relate to previous results from the Solar and Heliospheric
  Observatory (SOHO). Making use of the extended field of view of the
  STEREO instruments and the capability to view solar eruptions from
  vantage points away from the Sun-Earth line, this paper addresses CME
  morphology and the early evolution of CMEs including shock formation
  indicated by type II radio bursts and EUV disturbances. In situ
  observations from STEREO locations and Sun-Earth L1 are used to provide
  evidence to support the idea that all CMEs in the interplanetary medium
  may be flux ropes. Finally, the use of shock-flux rope morphology to
  determine the heliospheric magnetic field is discussed.

---------------------------------------------------------
Title: Erratum: "Behavior of Solar Cycles 23 and 24 Revealed by
    Microwave Observations" <A href="/abs/2012ApJ...750L..42G">(2012,
    ApJ, 750, L42)</A>
Authors: Gopalswamy, N.; Yashiro, S.; Mäkelä, P.; Michalek, G.;
   Shibasaki, K.; Hathaway, D. H.
2013ApJ...763L..24G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Homologous Flare-CME Events with and without a metric type
    II radio burst
Authors: Yashiro, S.; Gopalswamy, N.; Makela, P. A.
2012AGUFMSH43A2139Y    Altcode:
  Active region NOAA 11158 produced many flares and CMEs during its disk
  passage, out of which at least two can be considered as homologous. The
  events are the C6.6 flare at 06:51 UT and C9.4 flare at 12:41 UT on
  February 14, 2011. Both flares occurred at the same location (eastern
  edge of the active region) and have a similar decay of the GOES soft
  X-ray light curve. The associated CMEs were slow (319 km/s and 337
  km/s) and of similar widths (63 and 64 degree), but they had different
  radio signature. The second event was associated with a metric type
  II burst while the first one was not. The COR1 coronagraphs on board
  the STEREO spacecraft clearly show that the second CME propagated
  into the aftermath a preceding CME. These observations suggest that
  CME-CME interaction might be a key process in exciting the type II
  radio emission by slow CMEs.

---------------------------------------------------------
Title: A Space Weather Mission to the Earth's 5th Lagrangian Point
    (L5)
Authors: Howard, R. A.; Vourlidas, A.; Ko, Y.; Biesecker, D. A.;
   Krucker, S.; Murphy, N.; Bogdan, T. J.; St Cyr, O. C.; Davila, J. M.;
   Doschek, G. A.; Gopalswamy, N.; Korendyke, C. M.; Laming, J. M.;
   Liewer, P. C.; Lin, R. P.; Plunkett, S. P.; Socker, D. G.; Tomczyk,
   S.; Webb, D. F.
2012AGUFMSA13D..07H    Altcode:
  The highly successful STEREO mission, launched by NASA in 2006,
  consisted of two spacecraft in heliocentric orbit, one leading and
  one trailing the Earth and each separating from Earth at the rate
  of about 22.5 degrees per year. Thus the two spacecraft have been
  probing different probe/Sun/Earth angles. The utility of having remote
  sensing and in-situ instrumentation away from the Sun-Earth line was
  well demonstrated by STEREO. Here we propose the concept of a mission
  at the 5th Lagrangian "point" in the Earth/Sun system, located behind
  Earth about 60 degrees to the East of the Sun-Earth line. Such a mission
  would enable many aspects affecting space weather to be well determined
  and thus improving the prediction of the conditions of the solar wind
  as it impinges on geospace. For example, Coronal Mass Ejections can
  tracked for a significant distance toward Earth, new active regions
  can be observed before they become visible to the Earth observer, the
  solar wind can be measured before it rotates to Earth. The advantages
  of such a mission will be discussed in this presentation.

---------------------------------------------------------
Title: Tracking Solar Wind Input from the Sun to the Magnetosphere:
    2007-2011
Authors: St Cyr, O. C.; Mays, M. L.; Xie, H.; Gopalswamy, N.
2012AGUFMSH43C..02S    Altcode:
  During 2011 we were in the fortunate circumstance of having the twin
  STEREO spacecraft (Kaiser et al., 2008) pass through quadrature with
  the Sun-Earth line. As a result, the STEREO heliospheric imagers
  offer the possibility to track solar wind density features (e.g.,
  CMEs and CIRs) from the Sun-to-Earth. We have examined all instances
  of Dst &lt;-30 for this five year period, and we have identified the
  solar wind sources of these magnetospheric disturbances using remote
  sensing and in situ measurements.

---------------------------------------------------------
Title: Hot Precursor Ejecta and Other Peculiarities of the 2012 May
    17 Ground Level Enhancement Event
Authors: Gopalswamy, N.; Xie, H.; Nitta, N. V.; Usoskin, I.; Davila,
   J. M.
2012AGUFMSH21A2180G    Altcode:
  We report on the first Ground Level Enhancement (GLE) event of Solar
  Cycle 24, which occurred on May 17, 2012 from a well-connected region
  (NOAA AR 11476, N11W76) on the Sun. There has been a real dearth
  of GLE events during cycle 24: even though the Sun has reached its
  solar maximum phase, it has produced only this one GLE event. Over the
  first 4.5 years of solar cycle 23, there were 5 GLE events, which is
  roughly a third of all the events of that cycle. The recent GLE event
  was associated with a moderate flare with an X-ray size of only M5.1,
  well below the median flare size (X3.8) of cycle 23 GLE events. On
  the other hand, the associated CME was very fast (~2000 km/s),
  typical of GLE events. During cycle 23, the CME speeds in GLE events
  ranged from 1203 km/s to 3675 km/s with an average value of 2083 km/s
  (Gopalswamy et al., 2012). The speed of the cycle 24 GLE was measured
  accurately because it was a limb event in the SOHO coronagraphic field
  of view. The CME was also observed by the STEREO coronagraphs, which
  helped derive the initial acceleration as 1.5 km/s/s, which is also
  typical of GLE-producing CMEs. We were also able to directly determine
  the heliocentric distance of the CME (2.3 solar radii (Rs)) at the
  time of the release of GLE particles because there was a STEREO/COR1
  image precisely at the time of the particle release. This result
  is consistent with what was obtained for the cycle 23 GLE events,
  including the distance of the CME at the time of metric type II burst
  onset (1.3 Rs), indicating shock formation very close to the Sun
  ( ~0.3 Rs above the solar surface). We infer that the shock had to
  travel an additional 1 Rs before the GLE particles were released. The
  CME had a precursor in the form of a hot ejecta some tens of minutes
  before the main eruption. The preceding ejecta is termed hot because
  it was observed only in the 94 A images obtained by the Solar Dynamics
  Observatory (SDO). The 94 A images correspond to coronal a temperature
  of ~6MK. The lower temperature images such as at 193 A did not show
  the ejecta. The hot ejecta was accelerating and attained a speed
  of ~70 km/s before it was blasted by the big GLE-producing CMEs. We
  suggest that the hot material of the precursor ejecta might have been
  further accelerated by the CME-driven shock resulting in the GLE
  event. Reference Gopalswamy, N.,Xie, H., Yashiro, S., Akiyama, S.,
  Mäkelä, P., Usoskin, I. G., Properties of Ground Level Enhancement
  Events and the Associated Solar Eruptions During Solar Cycle 23,
  Space Science reviews, DOI: 10.1007/s11214-012-9890-4

---------------------------------------------------------
Title: Energetic particle and other space weather events of solar
    cycle 24
Authors: Gopalswamy, Nat
2012AIPC.1500...14G    Altcode: 2012arXiv1208.3951G
  We report on the space weather events of solar cycle 24 in comparison
  with those during a similar epoch in cycle 23. We find major differences
  in all space weather events: solar energetic particles, geomagnetic
  storms, and interplanetary shocks. Dearth of ground level enhancement
  (GLE) events and major geomagnetic storms during cycle 24 clearly
  standout. The space weather events seem to reflect the less frequent
  solar eruptions and the overall weakness of solar cycle 24.

---------------------------------------------------------
Title: Properties of Ground Level Enhancement Events and the
    Associated Solar Eruptions During Solar Cycle 23
Authors: Gopalswamy, N.; Xie, H.; Yashiro, S.; Akiyama, S.; Mäkelä,
   P.; Usoskin, I. G.
2012SSRv..171...23G    Altcode: 2012SSRv..tmp...38G; 2012arXiv1205.0688G
  Solar cycle 23 witnessed the most complete set of observations
  of coronal mass ejections (CMEs) associated with the Ground Level
  Enhancement (GLE) events. We present an overview of the observed
  properties of the GLEs and those of the two associated phenomena,
  viz., flares and CMEs, both being potential sources of particle
  acceleration. Although we do not find a striking correlation between
  the GLE intensity and the parameters of flares and CMEs, the solar
  eruptions are very intense involving X-class flares and extreme CME
  speeds (average ∼2000 km/s). An M7.1 flare and a 1200 km/s CME are
  the weakest events in the list of 16 GLE events. Most (80 %) of the CMEs
  are full halos with the three non-halos having widths in the range 167
  to 212 degrees. The active regions in which the GLE events originate are
  generally large: 1290 msh (median 1010 msh) compared to 934 msh (median:
  790 msh) for SEP-producing active regions. For accurate estimation of
  the CME height at the time of metric type II onset and GLE particle
  release, we estimated the initial acceleration of the CMEs using flare
  and CME observations. The initial acceleration of GLE-associated CMEs
  is much larger (by a factor of 2) than that of ordinary CMEs (2.3
  km/s<SUP>2</SUP> vs. 1 km/s<SUP>2</SUP>). We confirmed the initial
  acceleration for two events for which CME measurements are available
  in the inner corona. The GLE particle release is delayed with respect
  to the onset of all electromagnetic signatures of the eruptions:
  type II bursts, low frequency type III bursts, soft X-ray flares
  and CMEs. The presence of metric type II radio bursts some 17 min
  (median: 16 min; range: 3 to 48 min) before the GLE onset indicates
  shock formation well before the particle release. The release of GLE
  particles occurs when the CMEs reach an average height of ∼3.09 R
  <SUB> s </SUB> (median: 3.18 R <SUB> s </SUB>; range: 1.71 to 4.01
  R <SUB> s </SUB>) for well-connected events (source longitude in the
  range W20-W90). For poorly connected events, the average CME height at
  GLE particle release is ∼66 % larger (mean: 5.18 R <SUB> s </SUB>;
  median: 4.61 R <SUB> s </SUB>; range: 2.75-8.49 R <SUB> s </SUB>). The
  longitudinal dependence is consistent with shock accelerations because
  the shocks from poorly connected events need to expand more to cross
  the field lines connecting to an Earth observer. On the other hand, the
  CME height at metric type II burst onset has no longitudinal dependence
  because electromagnetic signals do not require magnetic connectivity
  to the observer. For several events, the GLE particle release is very
  close to the time of first appearance of the CME in the coronagraphic
  field of view, so we independently confirmed the CME height at particle
  release. The CME height at metric type II burst onset is in the narrow
  range 1.29 to 1.8 R <SUB> s </SUB>, with mean and median values of
  1.53 and 1.47 R <SUB> s </SUB>. The CME heights at metric type II
  burst onset and GLE particle release correspond to the minimum and
  maximum in the Alfvén speed profile. The increase in CME speed between
  these two heights suggests an increase in Alfvénic Mach number from
  2 to 3. The CME heights at GLE particle release are in good agreement
  with those obtained from the velocity dispersion analysis (Reames in
  Astrophys. J. 693:812, 2009a; Astrophys. J. 706:844, 2009b) including
  the source longitude dependence. We also discuss the implications of
  the delay of GLE particle release with respect to complex type III
  bursts by ∼18 min (median: 16 in; range: 2 to 44 min) for the flare
  acceleration mechanism. A similar analysis is also performed on the
  delay of particle release relative to the hard X-ray emission.

---------------------------------------------------------
Title: Determination of the Heliospheric Radial Magnetic Field from
    the Standoff Distance of a CME-driven Shock Observed by the STEREO
    Spacecraft
Authors: Poomvises, Watanachak; Gopalswamy, Nat; Yashiro, Seiji;
   Kwon, Ryun-Young; Olmedo, Oscar
2012ApJ...758..118P    Altcode:
  We report on the determination of radial magnetic field strength in the
  heliocentric distance range from 6 to 120 solar radii (R <SUB>⊙</SUB>)
  using data from Coronagraph 2 (COR2) and Heliospheric Imager I (HI1)
  instruments on board the Solar Terrestrial Relations Observatory
  spacecraft following the standoff-distance method of Gopalswamy &amp;
  Yashiro. We measured the shock standoff distance of the 2008 April
  5 coronal mass ejection (CME) and determined the flux-rope curvature
  by fitting the three-dimensional shape of the CME using the Graduated
  Cylindrical Shell model. The radial magnetic field strength is computed
  from the Alfvén speed and the density of the ambient medium. We also
  compare the derived magnetic field strength with in situ measurements
  made by the Helios spacecraft, which measured the magnetic field at
  the heliocentric distance range from 60 to 215 R <SUB>⊙</SUB>. We
  found that the radial magnetic field strength decreases from 28 mG at
  6 R <SUB>⊙</SUB> to 0.17 mG at 120 R <SUB>⊙</SUB>. In addition,
  we found that the radial profile can be described by a power law.

---------------------------------------------------------
Title: Preface
Authors: Gopalswamy, N.; Nitta, N. V.
2012SSRv..171....1G    Altcode: 2012SSRv..tmp...79G
  No abstract at ADS

---------------------------------------------------------
Title: Deflections of Fast Coronal Mass Ejections and the Properties
    of Associated Solar Energetic Particle Events
Authors: Kahler, S. W.; Akiyama, S.; Gopalswamy, N.
2012ApJ...754..100K    Altcode:
  The onset times and peak intensities of solar energetic particle (SEP)
  events at Earth have long been thought to be influenced by the open
  magnetic fields of coronal holes (CHs). The original idea was that a CH
  lying between the solar SEP source region and the magnetic footpoint of
  the 1 AU observer would result in a delay in onset and/or a decrease in
  the peak intensity of that SEP event. Recently, Gopalswamy et al. showed
  that CHs near coronal mass ejection (CME) source regions can deflect
  fast CMEs from their expected trajectories in space, explaining the
  appearance of driverless shocks at 1 AU from CMEs ejected near solar
  central meridian (CM). This suggests that SEP events originating in
  CME-driven shocks may show variations attributable to CH deflections
  of the CME trajectories. Here, we use a CH magnetic force parameter
  to examine possible effects of CHs on the timing and intensities of
  41 observed gradual E ~ 20 MeV SEP events with CME source regions
  within 20° of CM. We find no systematic CH effects on SEP event
  intensity profiles. Furthermore, we find no correlation between the
  CME leading-edge measured position angles and SEP event properties,
  suggesting that the widths of CME-driven shock sources of the SEPs are
  much larger than the CMEs. Independently of the SEP event properties,
  we do find evidence for significant CME deflections by CH fields in
  these events.

---------------------------------------------------------
Title: The Relationship Between the Expansion Speed and Radial Speed
    of CMEs Confirmed Using Quadrature Observations of the 2011 February
    15 CME
Authors: Gopalswamy, N.; Makela, P.; Yashiro, S.; Davila, J. M.
2012SunGe...7....7G    Altcode: 2012arXiv1205.0744G
  It is difficult to measure the true speed of Earth-directed CMEs
  from a coronagraph along the Sun-Earth line because of the occulting
  disk. However, the expansion speed (the speed with which the CME appears
  to spread in the sky plane) can be measured by such coronagraph. In
  order to convert the expansion speed to radial speed (which is
  important for space weather applications) one can use empirical
  relationship between the two that assumes an average width for all
  CMEs. If we have the width information from quadrature observations,
  we can confirm the relationship between expansion and radial speeds
  derived by Gopalswamy et al. (2009a). The STEREO spacecraft were in
  qudrature with SOHO (STEREO-A ahead of Earth by 87<SUP>o</SUP>and
  STEREO-B 94<SUP>o</SUP>behind Earth) on 2011 February 15, when a fast
  Earth-directed CME occurred. The CME was observed as a halo by the
  Large-Angle and Spectrometric Coronagraph (LASCO) on board SOHO. The
  sky-plane speed was measured by SOHO/LASCO as the expansion speed,
  while the radial speed was measured by STEREO-A and STEREO-B. In
  addition, STEREO-A and STEREO-B images measured the width of the
  CME, which is unknown from Earth view. From the SOHO and STEREO
  measurements, we confirm the relationship between the expansion
  speed (V<SUB>exp</SUB>) and radial speed (V<SUB>rad</SUB>) derived
  previously from geometrical considerations (Gopalswamy et al. 2009a):
  V<SUB>rad</SUB>=1/2 (1 + cot w)V<SUB>exp</SUB>, where w is the half
  width of the CME. STEREO-B images of the CME, we found that CME
  had a full width of 7 6<SUP>o</SUP>, so w=3 8<SUP>o</SUP>. This
  gives the relation as V<SUB>rad</SUB>=1.1 4 V<SUB>exp</SUB>. From
  LASCO observations, we measured V<SUB>exp</SUB>=897 km/s, so we get
  the radial speed as 10 2 3 km/s. Direct measurement of radial speed
  yields 945 km/s (STEREO-A) and 105 8 km/s (STEREO-B). These numbers
  are different only by 7.6 % and 3.4 % (for STEREO-A and STEREO-B,
  respectively) from the computed value.

---------------------------------------------------------
Title: Dependence of solar proton events on their associated
activities: Coronal mass ejection parameters
Authors: Park, J.; Moon, Y. -J.; Gopalswamy, N.
2012JGRA..117.8108P    Altcode: 2012JGRA..11708108P
  In this study we have examined the occurrence probability of solar
  proton events (SPEs) and their peak fluxes depending on coronal
  mass ejection (CME) parameters, linear speed (V), angular width
  (AW), and location (L). For this we used the NOAA SPE list and their
  associated CME data from 1997 to 2006. We found that the probability
  strongly depends on CME speed and angular width as follows. The
  highest association (36.1%) is found for the full halo CMEs with V
  ≥ 1500 kms<SUP>-1</SUP> but the lowest association (0.9%) is found
  for the partial halo CMEs with 400 kms<SUP>-1</SUP> ≤ V &lt; 1000
  kms<SUP>-1</SUP>. The SPE occurrence probabilities are different as
  much as 4.9 to 23 times according to CME speed and 1.6 to 6.5 times to
  angular width. The probabilities depending on CME speed and location
  increase from the eastern region to the western region and with
  speed. We have also examined the relationship between CME speed and
  SPE flux as well as its dependence on angular width (partial halo and
  full halo), longitude (east, center, and west) and direction parameter
  (&lt;0.4 and ≥0.4). Our results show that the relationships strongly
  depend on longitude as well as direction parameter.

---------------------------------------------------------
Title: Radio-loud CMEs from the disk center lacking shocks at 1 AU
Authors: Gopalswamy, N.; MäKelä, P.; Akiyama, S.; Yashiro, S.; Xie,
   H.; MacDowall, R. J.; Kaiser, M. L.
2012JGRA..117.8106G    Altcode: 2012arXiv1207.0021G; 2012JGRA..11708106G
  A coronal mass ejection (CME) associated with a type II burst and
  originating close to the center of the solar disk typically results
  in a shock at Earth in 2-3 days and hence can be used to predict
  shock arrival at Earth. However, a significant fraction (about 28%)
  of such CMEs producing type II bursts were not associated with
  shocks at Earth. We examined a set of 21 type II bursts observed by
  the Wind/WAVES experiment at decameter-hectometric (DH) wavelengths
  that had CME sources very close to the disk center (within a central
  meridian distance of 30 degrees), but did not have a shock at Earth. We
  find that the near-Sun speeds of these CMEs average to ∼644 km/s,
  only slightly higher than the average speed of CMEs associated with
  radio-quiet shocks. However, the fraction of halo CMEs is only ∼30%,
  compared to 54% for the radio-quiet shocks and 91% for all radio-loud
  shocks. We conclude that the disk-center radio-loud CMEs with no
  shocks at 1 AU are generally of lower energy and they drive shocks
  only close to the Sun and dissipate before arriving at Earth. There
  is also evidence for other possible processes that lead to the lack
  of shock at 1 AU: (i) overtaking CME shocks merge and one observes a
  single shock at Earth, and (ii) deflection by nearby coronal holes can
  push the shocks away from the Sun-Earth line, such that Earth misses
  these shocks. The probability of observing a shock at 1 AU increases
  rapidly above 60% when the CME speed exceeds 1000 km/s and when the
  type II bursts propagate to frequencies below 1 MHz.

---------------------------------------------------------
Title: On the Oscillatory and Non-oscillatory Loop Systems and
    Dynamical Processes during the X2.1 Solar Flare on 06 September 2011
Authors: Srivastava, Abhishek K.; Jain, Rajmal; Prasad Choudhary, Debi;
   Charan Dwivedi, Vidya; Aschwanden, Markus; Nitta, Nariaki; Gopalswamy,
   Nat; Awasthi, Arun Kumar; Chandra, Ramesh; Kayshap, Pradeep; Joshi,
   N. C.; Manoharan, P. K.; Norris, Max; Makela, Pertti; Mahalakshmi,
   K.; Elamathi, E.
2012cosp...39.1882S    Altcode: 2012cosp.meet.1882S
  No abstract at ADS

---------------------------------------------------------
Title: Magnetic Flux Imbalance in Active Regions NOAA 11283 and
    NOAA 11302
Authors: Prasad Choudhary, Debi; Jain, Rajmal; Charan Dwivedi, Vidya;
   Aschwanden, Markus; Nitta, Nariaki; Gopalswamy, Nat; Awasthi, Arun
   Kumar; Chandra, Ramesh; Srivastava, Abhishek K.; Manoharan, P. K.;
   Norris, Max; Mahalakshmi, K.; Elamathi, E.; Uddin, Wahab; Yashiro,
   Seiji
2012cosp...39..334P    Altcode: 2012cosp.meet..334P
  We investigate the magnetic flux imbalance of two active regions NOAA
  11302 and NOAA 11283 during their disk passage. The active region NOAA
  11302 appeared in the east limb on September 23, 2011 as beta-gamma
  complexity and produced 73 c-class, 27 M-class and 2 X-class flares
  many of which were associated with CMEs during the disk passage. The
  active region NOAA 11283 appeared on the east limb on September 1,
  2011 as beta-gamma complexity and produced 16 c-class, 9 m-class and 2
  x-class flares and CMEs. Both these active regions were of similar size
  but the evolution of magnetic complexity during their disk passage
  was very different. None of them made second disk passage. These
  two active regions represent two different class of activity. Among
  several reasons, the magnetic flux imbalance of the active regions
  result due to the presence of electric current with in the active
  regions. The high cadence full disk magnetograms obtained using the
  GONG and SDO-HMI instruments serve as the primary data source of this
  investigation. We relate the change in the magnetic flux imbalance
  with the flare occurrence in these two contrasting active regions.

---------------------------------------------------------
Title: Height of Shock Formation in the Solar Corona Inferred from
    Observations of Type II Radio Bursts and Coronal Mass Ejections
Authors: Gopalswamy, Nat; Jain, Rajmal; Prasad Choudhary, Debi;
   Charan Dwivedi, Vidya; Aschwanden, Markus; Nitta, Nariaki; Awasthi,
   Arun Kumar; Srivastava, Abhishek K.; Joshi, N. C.; Manoharan, P. K.;
   Makela, Pertti; Mahalakshmi, K.; Elamathi, E.; Uddin, Wahab; Yashiro,
   Seiji; Akiyam, Sachiko
2012cosp...39..653G    Altcode: 2012cosp.meet..653G
  No abstract at ADS

---------------------------------------------------------
Title: Multi-wavelength diagnostics of thermal and non-thermal
    sources in the 22 April 2011 flare event
Authors: Awasthi, Arun Kumar; Jain, Rajmal; Prasad Choudhary, Debi;
   Charan Dwivedi, Vidya; Aschwanden, Markus; Nitta, Nariaki; Gopalswamy,
   Nat; Chandra, Ramesh; Srivastava, Abhishek K.; Kayshap, Pradeep; Joshi,
   N. C.; Manoharan, P. K.; Norris, Max; Mahalakshmi, K.; Elamathi, E.;
   Uddin, Wahab
2012cosp...39...75A    Altcode: 2012cosp.meet...75A
  No abstract at ADS

---------------------------------------------------------
Title: Coronal Mass Ejections and Type II Radio Bursts from Active
    Region 11158
Authors: Yashiro, Seiji; Jain, Rajmal; Prasad Choudhary, Debi; Charan
   Dwivedi, Vidya; Aschwanden, Markus; Nitta, Nariaki; Gopalswamy, Nat;
   Awasthi, Arun Kumar; Chandra, Ramesh; Srivastava, Abhishek K.; Kayshap,
   Pradeep; Joshi, N. C.; Manoharan, P. K.; Makela, Pertti; Mahalakshmi,
   K.; Elam, E.
2012cosp...39.2205Y    Altcode: 2012cosp.meet.2205Y
  The NOAA active region (AR) 11158 emerged at around S20E50 on 2011
  February 10 as two bipoles and quickly developed into a large complex
  region. During 2011 February 13-17, AR 11158 produced 48 flares
  (&gt;C1 level) including the first X-class flare of 15 February,
  2011 in solar cycle 24. The 48 flares can be divided into four groups
  based on their location within the AR. We examined their associations
  of coronal mass ejections (CMEs) and metric type II radio bursts in
  order to find preferred locations of both the phenomena. We found that,
  out of 48 flares, 15 had associated CMEs, occurring frequently at the
  eastern edge of the AR. We also found that six flares were associated
  with type II radio bursts and all of them were associated with CMEs
  also. No type II was associated with the CME-less flare. This suggests
  that the CME association is a necessary condition for a flare to be
  associated with a metric type II burst.

---------------------------------------------------------
Title: The 3-D structure of CMEs as Inferred from Coronagraph
    Observations
Authors: Gopalswamy, Nat
2012cosp...39..649G    Altcode: 2012cosp.meet..649G
  Although the 3-D nature of coronal mass ejections (CMEs) has been
  suspected for a long time, it is only after the launch of the Solar
  Terrestrial Relations Observatory (STEREO) mission that it became
  possible to directly observe such structures. The twin instrument
  suite of the STEREO mission combined with the Solar and Heliospheric
  Observatory (SOHO) instruments helped enormously in obtaining the 3-D
  structure of CMEs. One of the earliest revelations is the confirmation
  that halo CMEs are like normal CMEs, except that they are viewed head on
  (or tail on) and are generally more energetic than the normal CMEs. EUV
  observations from STEREO and from the Solar Dynamics Observatory (SDO)
  also reveal the hemispheric nature of the early-phase shock-driving
  CMEs. STEREO coronagraphs provided broad-side views of such CMEs, so
  it became possible to estimate the width of the halo CMEs and hence
  validate CME cone models. In particular, the quadrature observations
  that became possible in 2010 and 2011 when the STEREO spacecraft were
  separated from the Sun-Earth line by about 90 degrees, revealed that
  CMEs are generally cone-shaped. Current theoretical ideas on the
  internal structure of CMEs suggest that a flux rope is central to
  the CME structure, which has considerable observational support. The
  cone model can be reconciled with the flux-rope structure with
  certain requirements on the thickness of the rope legs. The quadrature
  observations also helped us understand the relation between the radial
  and expansion speeds of CMEs, which were only known from empirical
  relations in the past. This paper highlights some key results obtained
  using observations from the declining phase of solar cycle 23 and the
  rise phase of solar cycle 24.

---------------------------------------------------------
Title: Inferences on the Behavior of Solar Cycle 24 from the Polar
    Coronal Hole Enhancement and the Rate of Prominence Eruptions Observed
    by the Nobeyama Radioheliograph
Authors: Gopalswamy, Nat; Yashiro, Seiji; Akiyama, Sachiko; Shibasaki,
   Kiyoto
2012cosp...39..651G    Altcode: 2012cosp.meet..651G
  After a prolonged minimum at the end of the solar cycle 23, solar
  activity picked up, but generally at low levels. One of the indicators
  of the level of activity is the rate of prominence eruptions (PEs)
  automatically detected in the images obtained by the Nobeyama
  Radioheliograph (NoRH). The relation between PEs and coronal mass
  ejections (CMEs) has a specific characteristic during solar minima:
  The PE latitude is generally higher than that of the associated CME nose
  indicating a general equatorward deflection of CMEs. The overall extent
  of the offset seems to be similar during the rise phases of cycle 23
  and 24, but there are far fewer PEs during cycle 24. The open field
  lines emanating from the polar coronal hole are thought to deflect
  CMEs away from the polar region. It is found that the offset starts
  in the year 2007, roughly two years before the deepest solar minimum
  and continued into the rise phase of the solar cycle 24. A significant
  north-south asymmetry is observed in the deflection process, which can
  be explained by the different behavior of the north and south polar
  coronal holes. We also constructed NoRH microwave butterfly diagram
  using 17 GHz images, which reveal that the solar activity has reached
  the maximum phase in the north pole. This is further confirmed by the
  latitudes of prominence eruptions reminiscent of the maximum phase.

---------------------------------------------------------
Title: A Study of the 12 June 2010 C6.1/SF flare associated with a
    CME, surge and energetic particles
Authors: Uddin, Wahab; Jain, Rajmal; Manoharan, P. K.; Prasad
   Choudhary, Debi; Charan Dwivedi, Vidya; Aschwanden, Markus; Nitta,
   Nariaki; Gopalswamy, Nat; Awasthi, Arun Kumar; Chandra, Ramesh;
   Srivastava, Abhishek K.; Kayshap, Pradeep; Joshi, N. C.; Norris, Max;
   Makela, Pertti; Mahalaksh, K.
2012cosp...39.2026U    Altcode: 2012cosp.meet.2026U
  In this paper, we present the multiwavelength analysis of the C6.1/SF
  flare on 12 June 2010 from NOAA AR 11081. The flare was observed by
  various ground based (ARIES H-alpha; HIRAS Radio) and space borne
  observatories (SDO, STEREO, SOHO, GOES). The flare was accompanied by
  a spray/surge and a slow coronal mass ejection (CME) that propagated
  with a speed of ~382 km/s. The eruption was associated with a weak
  solar energetic particle (SEP) event. The solar source of the eruption
  was a rapid emerging flux region. The eruption was also associated
  with the three major types of radio bursts (type II, III and IV). The
  interesting observation is the shock production (type II burst and
  SEP event) by a relatively slow CME. We interpret the results in the
  light of existing theories.

---------------------------------------------------------
Title: Global Cooperation in the Capacity Building Activities on
    Sun-Earth Connection Studies
Authors: Gopalswamy, Nat; Davila, Joseph; Luebken, Franz-Josef;
   Shepherd, Marianna; Tsuda, Toshitaka
2012cosp...39..650G    Altcode: 2012cosp.meet..650G
  The importance of global cooperation in Sun-Earth connection studies
  can be readily seen in the formation of a number of international
  collaborative programs such as the Climate and Weather of the
  Sun Earth System (CAWSES) by SCOSTEP* and the International Space
  Weather Initiative (ISWI). ISWI is the continuation of the successful
  International Heliophysical Year (IHY) program. These programs have
  brought scientists together to tackle issues of solar-terrestrial
  phenomena. An important element of these organizations is capacity
  building activities, which include deployment of low-cost ground
  based instruments for Sun-Earth connection studies and training young
  people (scientists and graduate students) from developing countries
  to operate these instruments and become members of the international
  solar-terrestrial scientific community. The training also helps young
  people to make use of data from the vast array of space and ground based
  instruments currently available for Sun-Earth connection studies. This
  paper presents a summary of CAWSES and ISWI activities that promote
  space Sun-Earth connection studies via complementary approaches in
  international scientific collaborations, capacity building, and public
  outreach. *Scientific Committee on Solar Terrestrial Physics (SCOSTEP)
  is an Interdisciplinary Body of the International Council for Science
  with representations from COSPAR, IAU, IUGG/IAGA, IUPAP, IAMAS, SCAR,
  and URSI (http://www.yorku.ca/scostep)

---------------------------------------------------------
Title: The location of solar metric type II radio bursts with respect
    to the associated coronal mass ejections
Authors: Ramesh, R.; Gopalswamy, Nat; Lakshmi, Anna M.; Kathiravan, C.
2012cosp...39.1549R    Altcode: 2012cosp.meet.1549R
  No abstract at ADS

---------------------------------------------------------
Title: A Global View of the Energetic Solar Eruptions during 2012
    January 19-27
Authors: Gopalswamy, Nat; Davila, Joseph; Kaiser, Michael; Macdowall,
   Robert; Cyr, Chris; Xie, Hong; Makela, Pertti; Yashiro, Seiji;
   Poomvises, Watanachak
2012cosp...39..652G    Altcode: 2012cosp.meet..652G
  The rise phase of solar cycle was generally unremarkable and subdued in
  terms of large solar eruptive events that had significant heliospheric
  consequences. Towards the end of the rise phase, a series of three
  coronal mass ejections (CMEs) originated from NOAA active region
  11402 that were accompanied by M or X-class flares, significant solar
  energetic particle events (including the largest event as of this
  writing), interplanetary type II radio bursts, and shocks. While
  the particle radiation was very intense in two events, the plasma
  impact on the magnetosphere was moderate. This paper provides an
  overview of the eruptive events, focusing on the kinematic evolution
  of the CMEs in relation to the interplanetary type II radio bursts
  and shocks. In particular we compare the drift rate variation of
  the interplanetary type II bursts with the speed variation of the
  CMEs obtained from heliospheric imaging. We make use of data from the
  Solar and Heliospheric Observatory (SOHO), Solar Terrestrial Relations
  Observatory (STEREO), Solar Dynamics Observatory (SDO), Wind, GOES,
  and ground based observatories for this investigation.

---------------------------------------------------------
Title: Solar Energetic Particle Events and Associated CMEs during
    the Rising Phases of Solar Cycle 23 and 24 - A Comparative study
Authors: Chandra, Ramesh; Jain, Rajmal; Prasad Choudhary, Debi; Charan
   Dwivedi, Vidya; Aschwanden, Markus; Nitta, Nariaki; Gopalswamy, Nat;
   Awasthi, Arun Kumar; Srivastava, Abhishek K.; Kayshap, Pradeep; Joshi,
   N. C.; Manoharan, P. K.; Makela, Pertti; Mahalakshmi, K.; Elamathi,
   E.; Uddi, Wahab
2012cosp...39..303C    Altcode: 2012cosp.meet..303C
  No abstract at ADS

---------------------------------------------------------
Title: Flare and CME Productivity of Active Region 11429
Authors: Yashiro, Seiji; Gopalswamy, N.; Akiyama, S.; Michalek, G.;
   Makela, P.
2012shin.confE.161Y    Altcode:
  Active region NOAA 11429 produced 3 X- and 15 M-class flares
  duringMarch 2 to 13. We examined their CME association using
  SOHO/LASCO andSTEREO/COR1 and found that 8 flares were CME-associated
  and theremaining 10 were CME-less. We found that the 10 CME-less
  flaresoccurred successively between 19 UT on March 5 and 22 UT on
  March 6. Theintensities of the flares were relatively low (range:
  M1.0 - M2.1;median: M1.3), but the occurrence rate was very high
  (at 3-hourintervals on average). During this period a CME erupted
  from thesouthern edge of this region but the X-ray enhancement was
  not detectedby GOES. The CME-associated flares are relatively intense
  (range: M2.0 -X5.4; median M8.1), and the waiting times (intervals
  between successiveflares) are longer ( 36 hours on average) than those
  of the CME-lessflares. We present a comprehensive view of flare-CME
  activities of theactive region 11429 and discuss the difference of
  the CME-associated andCME-less flares.

---------------------------------------------------------
Title: The Location of Solar Metric Type II Radio Bursts with Respect
    to the Associated Coronal Mass Ejections
Authors: Ramesh, R.; Lakshmi, M. Anna; Kathiravan, C.; Gopalswamy,
   N.; Umapathy, S.
2012ApJ...752..107R    Altcode:
  Forty-one solar type II radio bursts located close to the solar limb
  (projected radial distance r &gt;~ 0.8 R <SUB>⊙</SUB>) were observed
  at 109 MHz by the radioheliograph at the Gauribidanur observatory
  near Bangalore during the period 1997-2007. The positions of the
  bursts were compared with the estimated location of the leading edge
  (LE) of the associated coronal mass ejections (CMEs) close to the
  Sun. 38/41 of the type II bursts studied were located either at or
  above the LE of the associated CME. In the remaining 3/41 cases, the
  burst was located behind the LE of the associated CME at a distance
  of &lt;0.5 R <SUB>⊙</SUB>. Our results suggest that nearly all the
  metric type II bursts are driven by the CMEs.

---------------------------------------------------------
Title: A study of cold-high density materials in ICMEs
Authors: Akiyama, Sachiko; Gopalswamy, Nat; Yashiro, Seiji; Kim,
   Rok-Soon; Mäkelä, Pertti; Xie, Hong; Marubashi, Katsuhide
2012shin.confE.136A    Altcode:
  Eruptive prominence (EP) is dynamic and is well known as the core of
  coronal mass ejections (CMEs) near the Sun. Reports of filament material
  in in-situ observations are rare, even though EPs are identified as a
  solar source of an interplanetary CMEs. We studied cold high-density
  material in 54 ICMEs (1997 - 2006), whose solar source was located
  within 15 degrees from the disk center. All events were part of the
  Living with a Star (LWS) Coordinated Data-Analysis Workshop (CDAW) known
  as the 'Flux Rope CDAW', which took place in 2012 and 2011. Using SXT,
  EIT, TRACE and Ha data, we carefully checked the solar sources to see
  whether EPs including filament disappearances were observed coincidently
  or not. We found 33 (21) CME-ICME pairs associated with (without)
  EPs. Then we selected cold high-density bumps within the overall
  interval of the ICMEs, which satisfied the following conditions: 1)
  There is a proton and He++ density increase for more than two hours. 2)
  Maximum proton temperature remains lower than the average temperature of
  the ICME. 3) Exclude density increases at the boundary between sheath
  and ICME. 4) In cases where the ICME is followed by another ICME or
  a corotating interaction region, exclude the density increase at the
  rear boundary. With these criteria, we found 20 (10) cold high-density
  material in ICMEs with (without) EPs. We found that the average proton
  and He++ density increases in ICMEs associated with EP (15.8 and 0.56
  /cm^3) are larger than in ICMEs associated with non-EPs (10.7 and 0.34
  /cm^3). There is no preferred location of the density increase during
  the ICME. Average location of increase is near the center of the ICME.

---------------------------------------------------------
Title: Behavior of Solar Cycles 23 and 24 Revealed by Microwave
    Observations
Authors: Gopalswamy, N.; Yashiro, S.; Mäkelä, P.; Michalek, G.;
   Shibasaki, K.; Hathaway, D. H.
2012ApJ...750L..42G    Altcode: 2012arXiv1204.2816G
  Using magnetic and microwave butterfly diagrams, we compare the
  behavior of solar polar regions to show that (1) the polar magnetic
  field and the microwave brightness temperature during solar minimum
  substantially diminished during the cycle 23/24 minimum compared to
  the 22/23 minimum. (2) The polar microwave brightness temperature
  (Tb) seems to be a good proxy for the underlying magnetic field
  strength (B). The analysis indicates a relationship, B = 0.0067Tb -
  70, where B is in G and Tb in K. (3) Both the brightness temperature
  and the magnetic field strength show north-south asymmetry most of
  the time except for a short period during the maximum phase. (4) The
  rush-to-the-pole phenomenon observed in the prominence eruption (PE)
  activity seems to be complete in the northern hemisphere as of 2012
  March. (5) The decline of the microwave brightness temperature in the
  north polar region to the quiet-Sun levels and the sustained PE activity
  poleward of 60<SUP>o</SUP>N suggest that solar maximum conditions have
  arrived at the northern hemisphere. The southern hemisphere continues
  to exhibit conditions corresponding to the rise phase of solar cycle 24.

---------------------------------------------------------
Title: Comparison between Major Confined and Eruptive Flares
Authors: Gopalswamy, N.; Yashiro, S.; Mäkelä, P.; Dennis, B. R.
2012AAS...22042402G    Altcode:
  Statistical studies have shown that a large fraction of major solar
  flares (42% M-class and 15% X-class) are not associated with coronal
  mass ejections (CMEs). The CME-less flares are confined flares as
  opposed to the eruptive flares associated with CMEs. Confined flares
  are certainly good particle accelerators as inferred from intense
  microwave, hard X-ray, and gamma-ray emissions. Note that a single
  acceleration mechanism operates in confined flares, whereas eruptive
  flares can have both flare-resident and shock accelerations (the shock
  acceleration is due to energetic CMEs). In this paper, we report on
  a statistical study of more than two dozen confined flares with soft
  X-ray flare size exceeding M5 in comparison with a control sample of
  eruptive flares with similar soft X-ray flare size. We compare the
  microwave and X-ray emission characteristics in the two populations;
  these emissions correspond to sunward energy flow. For a given X-ray
  flare size, the microwave flux is scattered over a wider range for
  the eruptive flares when compared to the confined flares. We also
  compare the metric and longer wavelength radio bursts between the two
  populations; these emissions correspond to the flow of nonthermal
  electrons away from the Sun. We find that almost all the confined
  flares lack metric radio bursts, suggesting that there is very little
  flow of energy into the interplanetary medium. On the other hand, there
  is high degree of association between eruptive flares and metric radio
  bursts. This suggests that in confined flares the accelerated electrons
  have no access to open magnetic field lines. Finally, we examined the
  association of EUV waves with the two flare populations. While we find
  EUV waves in most of the eruptive flares, there was no confined flare
  with EUV waves. This suggests that CMEs is a necessary condition for
  the generation of global waves.

---------------------------------------------------------
Title: A Comparison of Solar Energetic Particle Events with 1 AU
    Magnetic Field Connections to Solar Coronal Holes
Authors: Kahler, Stephen W.; Arge, C. N.; Akiyama, S.; Gopalswamy, N.
2012AAS...22020436K    Altcode:
  The observed properties of solar energetic particle (SEP) events are
  known to depend on the source locations and speeds of their associated
  coronal mass ejections (CMEs). However, the CME characteristics cannot
  account for a great deal of the variability in SEP event intensities and
  time scales. It has long been suspected that the presence of coronal
  holes (CHs) near the CMEs or near the 1 AU magnetic footpoints may
  be an important factor in SEP events. We use a group of E 20 MeV SEP
  events with origins near solar central meridian to look for possible
  CH effects. The CH connections from 1 AU are determined from the 4-day
  forecast maps based on Mount Wilson Observatory and the National Solar
  Observatory synoptic magnetic field maps and the Wang-Sheeley-Arge
  model of solar wind propagation. The observed in situ magnetic field
  polarities and solar wind speeds at SEP event onsets test the forecast
  accuracies to select the best SEP/CH connection events for analysis. The
  SEP event properties are then compared with the relative locations and
  separations of the CMEs and the 1 AU footpoints to determine whether
  and how the CHs may affect SEP events.

---------------------------------------------------------
Title: CME-associated Radio Bursts from Satellite Observations
Authors: Gopalswamy, Nat
2012AAS...22030403G    Altcode:
  Coronal mass ejections (CMEs) are closely associated with various types
  of radio bursts from the Sun. All radio bursts are due to nonthermal
  electrons, which are accelerated during the eruption of CMEs. Radio
  bursts at frequencies below about 15 MHz are of particular interest
  because they are associated with energetic CMEs that contribute to
  severe space weather. The low-frequency bursts need to be observed
  primarily from space because of the ionospheric cutoff. The main
  CME-related radio bursts are associated are: type III bursts due to
  accelerated electrons propagating along open magnetic field lines, type
  II bursts due to electrons accelerated in shocks, and type IV bursts
  due to electrons trapped in post-eruption arcades behind CMEs. This
  paper presents a summary of results obtained during solar cycle 23
  primarily using the white-light coronagraphic observations from the
  Solar Heliospheric Observatory (SOHO) and the WAVES experiment on
  board Wind. Particular emphasis will be placed on what we can learn
  about particle acceleration in the coronal and interplanetary medium
  by analyzing the CMEs and the associated radio bursts.

---------------------------------------------------------
Title: On the Relationship Between a High-frequency Type II Solar
    Radio Burst and Coronal Mass Ejection on February 13, 2011
Authors: Cho, Kyung-Suk; Gopalswamy, N.; Kwon, R.; Kim, R.; Yashiro, S.
2012AAS...22052502C    Altcode:
  We examine the relationship between a metric type II radio burst that
  started from an unusually high frequency of 425 MHz (fundamental
  component) and the associated white-light coronal mass ejection on
  2011 February 11. The radio burst had a drift rate of 3 MHz/sec,
  indicating a relatively high shock speed. The question we would like
  to answer is whether the high frequency type II burst is generated by
  the CME. To avoid the ambiguity normally caused by the use of density
  models in the analysis of type II bursts, we measure the coronal
  electron density by applying automated emission measure analysis code
  developed by Aschwanden et al. (2011) to AIA/SDO images in 6 coronal
  filters. From SDO AIA observations we find that a loop-like erupting
  front sweeps across high density coronal loops near the start time of
  the burst (17:34:15 UT). The deduced height of shock formation (1.2
  Rs) from the measured density is comparable to the height (1.15 Rs)
  of the CME observed by STEREO/EUVI. Thus we conclude that the high
  frequency type II burst could be generated at locations where the CME
  passes through the high density loops in the low corona.

---------------------------------------------------------
Title: Propagation Characteristics of CMEs Associated Magnetic Clouds
    and Ejecta
Authors: Kim, Roksoon; Gopalswamy, N.; Cho, K.; Moon, Y.; Yashiro, S.
2012AAS...22052108K    Altcode:
  We have investigated the characteristics of magnetic cloud (MC)
  and ejecta (EJ) associated coronal mass ejections (CMEs) based on
  the assumption that all CMEs have a flux rope structure. For this,
  we used 54 CMEs and their interplanetary counter parts (interplanetary
  CMEs: ICMEs) that constitute the list of events used by the NASA/LWS
  Coordinated Data Analysis Workshop (CDAW) on CME flux ropes. We
  considered the location, angular width, speed, and direction parameter,
  D, that quantifies the propagation direction of a CME. For the 54
  CDAW events, we found several properties of the CMEs as follows:
  (1) the average value of D for the 23 MCs (0.62) is larger than that
  for the 31 EJs (0.49), which indicates that the MC-associated CMEs
  propagate more directly to the Earth than the EJ-associated CMEs; (2)
  comparison between the direction parameter and the source location
  shows that the majority of the MC-associated CMEs are ejected along
  the radial direction, while many of the EJ-associated CMEs are ejected
  non-radially; (3) the mean speed of MC-associated CMEs (946 km/s)
  is faster than that of EJ-associated CMEs (771 km/s). For seven
  very fast CMEs (&gt; 1500 km/s), all CMEs with large D (&gt; 0.4)
  are associated with MCs and the CMEs with small D are associated with
  EJs. On the basis of these results, we suggest that the CME trajectory
  essentially decides the observed ICME structure.

---------------------------------------------------------
Title: Factors affecting the intensity of solar energetic particle
    events
Authors: Gopalswamy, Nat
2012AIPC.1436..247G    Altcode: 2011arXiv1109.2933G
  This paper updates the influence of environmental and source factors
  of shocks driven by coronal mass ejections (CMEs) that are likely to
  influence the solar energetic particle (SEP) events. The intensity
  variation due to CME interaction reported in [1] is confirmed by
  expanding the investigation to all the large SEP events of solar cycle
  23. The large SEP events are separated into two groups, one associated
  with CMEs running into other CMEs, and the other with CMEs running
  into the ambient solar wind. SEP events with CME interaction generally
  have a higher intensity. New possibilities such as the influence of
  coronal holes on the SEP intensity are also discussed. For example,
  the presence of a large coronal hole between a well-connected eruption
  and the solar disk center may render the shock poorly connected because
  of the interaction between the CME and the coronal hole. This point is
  illustrated using the 2004 December 3 SEP event delayed by about 12
  hours from the onset of the associated CME. There is no other event
  at the Sun that can be associated with the SEP onset. This event is
  consistent with the possibility that the coronal hole interaction
  influences the connectivity of the CMEs that produce SEPs, and hence
  the intensity of the SEP event.

---------------------------------------------------------
Title: Erratum to: Relation Between Type II Bursts and CMEs Inferred
    from STEREO Observations
Authors: Gopalswamy, N.; Thompson, W. T.; Davila, J. M.; Kaiser,
   M. L.; Yashiro, S.; Mäkelä, P.; Michalek, G.; Bougeret, J. -L.;
   Howard, R. A.
2012SoPh..277..459G    Altcode: 2011SoPh..tmp..421G; 2011SoPh..tmp..425G
  No abstract at ADS

---------------------------------------------------------
Title: Coronal mass ejection-driven shocks and the associated sudden
    commencements/sudden impulses
Authors: Veenadhari, B.; Selvakumaran, R.; Singh, Rajesh; Maurya,
   Ajeet K.; Gopalswamy, N.; Kumar, Sushil; Kikuchi, T.
2012JGRA..117.4210V    Altcode: 2012JGRA..11704210V
  Interplanetary (IP) shocks are mainly responsible for the sudden
  compression of the magnetosphere, causing storm sudden commencement
  (SC) and sudden impulses (SIs) which are detected by ground-based
  magnetometers. On the basis of the list of 222 IP shocks compiled
  by Gopalswamy et al. (2010), we have investigated the dependence of
  SC/SIs amplitudes on the speed of the coronal mass ejections (CMEs)
  that drive the shocks near the Sun as well as in the interplanetary
  medium. We find that about 91% of the IP shocks were associated with
  SC/SIs. The average speed of the SC/SI-associated CMEs is 1015 km/s,
  which is almost a factor of 2 higher than the general CME speed. When
  the shocks were grouped according to their ability to produce type II
  radio burst in the interplanetary medium, we find that the radio-loud
  (RL) shocks produce a much larger SC/SI amplitude (average ∼32 nT)
  compared to the radio-quiet (RQ) shocks (average ∼19 nT). Clearly,
  RL shocks are more effective in producing SC/SIs than the RQ shocks. We
  also divided the IP shocks according to the type of IP counterpart of
  interplanetary CMEs (ICMEs): magnetic clouds (MCs) and nonmagnetic
  clouds. We find that the MC-associated shock speeds are better
  correlated with SC/SI amplitudes than those associated with non-MC
  ejecta. The SC/SI amplitudes are also higher for MCs than ejecta. Our
  results show that RL and RQ type of shocks are important parameters
  in producing the SC/SI amplitude.

---------------------------------------------------------
Title: Understanding shock dynamics in the inner heliosphere with
modeling and Type II radio data: The 2010-04-03 event
Authors: Xie, H.; Odstrcil, D.; Mays, L.; St. Cyr, O. C.; Gopalswamy,
   N.; Cremades, H.
2012JGRA..117.4105X    Altcode: 2012JGRA..11704105X
  The 2010 April 03 solar event was studied using observations from STEREO
  SECCHI, SOHO LASCO, and Wind kilometric Type II data (kmTII) combined
  with WSA-Cone-ENLIL model simulations performed at the Community
  Coordinated Modeling Center (CCMC). In particular, we identified the
  origin of the coronal mass ejection (CME) using STEREO EUVI and SOHO
  EIT images. A flux-rope model was fit to the SECCHI A and B, and LASCO
  images to determine the CME's direction, size, and actual speed. J-maps
  from STEREO COR2/HI-1/HI-2 and simulations from CCMC were used to study
  the formation and evolution of the shock in the inner heliosphere. In
  addition, we also studied the time-distance profile of the shock
  propagation from kmTII radio burst observations. The J-maps together
  with in-situ data from the Wind spacecraft provided an opportunity
  to validate the simulation results and the kmTII prediction. Here we
  report on a comparison of two methods of predicting interplanetary
  shock arrival time: the ENLIL model and the kmTII method; and
  investigate whether or not using the ENLIL model density improves
  the kmTII prediction. We found that the ENLIL model predicted the
  kinematics of shock evolution well. The shock arrival times (SAT)
  and linear-fit shock velocities in the ENLIL model agreed well with
  those measurements in the J-maps along both the CME leading edge and
  the Sun-Earth line. The ENLIL model also reproduced most of the large
  scale structures of the shock propagation and gave the SAT prediction
  at Earth with an error of ∼1 ± 7 hours. The kmTII method predicted
  the SAT at Earth with an error of ∼15 hours when using n<SUB>0</SUB> =
  4.16 cm<SUP>-3</SUP>, the ENLIL model plasma density near Earth; but it
  improved to ∼2 hours when using n<SUB>0</SUB> = 6.64 cm<SUP>-3</SUP>,
  the model density near the CME leading edge at 1 AU.

---------------------------------------------------------
Title: Comparison of Dst forecast models for intense geomagnetic
    storms
Authors: Ji, Eun-Young; Moon, Y. -J.; Gopalswamy, N.; Lee, D. -H.
2012JGRA..117.3209J    Altcode: 2012JGRA..11703209J
  We have compared six Dst forecast models using 63 intense geomagnetic
  storms (Dst ≤ -100 nT) that occurred from 1998 to 2006. For
  comparison, we estimated linear correlation coefficients and RMS
  errors between the observed Dst data and the predicted Dst during the
  geomagnetic storm period as well as the difference of the value of
  minimum Dst (ΔDst<SUB>min</SUB>) and the difference in the absolute
  value of Dst minimum time (Δt<SUB>Dst</SUB>) between the observed
  and the predicted. As a result, we found that the model by Temerin
  and Li (2002, 2006) gives the best prediction for all parameters when
  all 63 events are considered. The model gives the average values:
  the linear correlation coefficient of 0.94, the RMS error of 14.8
  nT, the ΔDst<SUB>min</SUB> of 7.7 nT, and the absolute value of
  Δt<SUB>Dst</SUB> of 1.5 hour. For further comparison, we classified
  the storm events into two groups according to the magnitude of Dst. We
  found that the model of Temerin and Lee (2002, 2006) is better than the
  other models for the events having -100 ≤ Dst &lt; -200 nT, and three
  recent models (the model of Wang et al. (2003), the model of Temerin
  and Li (2002, 2006), and the model of Boynton et al. (2011b)) are better
  than the other three models for the events having Dst ≤ -200 nT.

---------------------------------------------------------
Title: Magnetic Field Strength in the Upper Solar Corona Using
    White-light Shock Structures Surrounding Coronal Mass Ejections
Authors: Kim, R. -S.; Gopalswamy, N.; Moon, Y. -J.; Cho, K. -S.;
   Yashiro, S.
2012ApJ...746..118K    Altcode: 2011arXiv1112.0288K
  To measure the magnetic field strength in the solar corona,
  we examined 10 fast (&gt;=1000 km s<SUP>-1</SUP>) limb coronal
  mass ejections(CMEs) that show clear shock structures in Solar and
  Heliospheric Observatory/Large Angle and Spectrometric Coronagraph
  images. By applying the piston-shock relationship to the observed
  CME's standoff distance and electron density compression ratio, we
  estimated the Mach number, Alfvén speed, and magnetic field strength
  in the height range 3-15 solar radii (R<SUB>s</SUB> ). The main results
  from this study are as follows: (1) the standoff distance observed in
  the solar corona is consistent with those from a magnetohydrodynamic
  model and near-Earth observations; (2) the Mach number as a shock
  strength is in the range 1.49-3.43 from the standoff distance ratio,
  but when we use the density compression ratio, the Mach number is in
  the range 1.47-1.90, implying that the measured density compression
  ratio is likely to be underestimated owing to observational limits;
  (3) the Alfvén speed ranges from 259 to 982 km s<SUP>-1</SUP> and
  the magnetic field strength is in the range 6-105 mG when the standoff
  distance is used; (4) if we multiply the density compression ratio by
  a factor of two, the Alfvén speeds and the magnetic field strengths
  are consistent in both methods; and (5) the magnetic field strengths
  derived from the shock parameters are similar to those of empirical
  models and previous estimates.

---------------------------------------------------------
Title: Interplanetary shocks lacking type II radio bursts.
Authors: Gopalswamy, N.; Xie, H.; Makela, P.; Akiyama, S.; Yashiro,
   S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. -L.
2012yCat..17101111G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Coronal Magnetic Field Measurement from EUV Images Made by
    the Solar Dynamics Observatory
Authors: Gopalswamy, Nat; Nitta, Nariaki; Akiyama, Sachiko; Mäkelä,
   Pertti; Yashiro, Seiji
2012ApJ...744...72G    Altcode: 2011arXiv1109.2925G
  By measuring the geometrical properties of the coronal mass ejection
  (CME) flux rope and the leading shock observed on 2010 June 13 by
  the Solar Dynamics Observatory (SDO) mission's Atmospheric Imaging
  Assembly we determine the Alfvén speed and the magnetic field strength
  in the inner corona at a heliocentric distance of ~1.4 Rs. The basic
  measurements are the shock standoff distance (ΔR) ahead of the CME
  flux rope, the radius of curvature of the flux rope (R <SUB>c</SUB>),
  and the shock speed. We first derive the Alfvénic Mach number (M) using
  the relationship, ΔR/R <SUB>c</SUB> = 0.81[(γ-1) M <SUP>2</SUP> +
  2]/[(γ+1)(M <SUP>2</SUP> - 1)], where γ is the only parameter that
  needed to be assumed. For γ = 4/3, the Mach number declined from
  3.7 to 1.5 indicating shock weakening within the field of view of the
  imager. The shock formation coincided with the appearance of a type II
  radio burst at a frequency of ~300 MHz (harmonic component), providing
  an independent confirmation of the shock. The shock compression ratio
  derived from the radio dynamic spectrum was found to be consistent
  with that derived from the theory of fast-mode MHD shocks. From the
  measured shock speed and the derived Mach number, we found the Alfvén
  speed to increase from ~140 km s<SUP>-1</SUP> to 460 km s<SUP>-1</SUP>
  over the distance range 1.2-1.5 Rs. By deriving the upstream plasma
  density from the emission frequency of the associated type II radio
  burst, we determined the coronal magnetic field to be in the range
  1.3-1.5 G. The derived magnetic field values are consistent with other
  estimates in a similar distance range. This work demonstrates that the
  EUV imagers, in the presence of radio dynamic spectra, can be used as
  coronal magnetometers.

---------------------------------------------------------
Title: Relation Between the 3D-Geometry of the Coronal Wave and
    Associated CME During the 26 April 2008 Event
Authors: Temmer, M.; Veronig, A. M.; Gopalswamy, N.; Yashiro, S.
2012esrs.book..115T    Altcode:
  We study the kinematical characteristics and 3D geometry of
  a large-scale coronal wave that occurred in association with the
  26 April 2008 flare-CME event. The wave was observed with the EUVI
  instruments aboard both STEREO spacecraft (STEREO-A and STEREO-B)
  with a mean speed of ∼ 240 km s<SUP>-1</SUP>. The wave is more
  pronounced in the eastern propagation direction, and is thus, better
  observable in STEREO-B images. From STEREO-B observations we derive
  two separate initiation centers for the wave, and their locations fit
  with the coronal dimming regions. Assuming a simple geometry of the
  wave we reconstruct its 3D nature from combined STEREO-A and STEREO-B
  observations. We find that the wave structure is asymmetric with an
  inclination toward East. The associated CME has a deprojected speed
  of ∼ 750±50 km s<SUP>-1</SUP>, and it shows a non-radial outward
  motion toward the East with respect to the underlying source region
  location. Applying the forward fitting model developed by Thernisien,
  Howard, and Vourlidas (Astrophys. J. 652, 763, 2006), we derive the
  CME flux rope position on the solar surface to be close to the dimming
  regions. We conclude that the expanding flanks of the CME most likely
  drive and shape the coronal wave.

---------------------------------------------------------
Title: The relation between coronal holes and coronal mass ejections
    during the rise, maximum, and declining phases of Solar Cycle 23
Authors: Mohamed, A. A.; Gopalswamy, N.; Yashiro, S.; Akiyama, S.;
   Mäkelä, P.; Xie, H.; Jung, H.
2012JGRA..117.1103M    Altcode: 2012JGRA..11701103M
  We study the interaction between coronal holes (CHs) and coronal mass
  ejections (CMEs) using a resultant force exerted by all the coronal
  holes present on the disk and is defined as the coronal hole influence
  parameter (CHIP). The CHIP magnitude for each CH depends on the CH area,
  the distance between the CH centroid and the eruption region, and the
  average magnetic field within the CH at the photospheric level. The
  CHIP direction for each CH points from the CH centroid to the eruption
  region. We focus on Solar Cycle 23 CMEs originating from the disk
  center of the Sun (central meridian distance ≤15°) and resulting
  in magnetic clouds (MCs) and non-MCs in the solar wind. The CHIP is
  found to be the smallest during the rise phase for MCs and non-MCs. The
  maximum phase has the largest CHIP value (2.9 G) for non-MCs. The CHIP
  is the largest (5.8 G) for driverless (DL) shocks, which are shocks at
  1 AU with no discernible MC or non-MC. These results suggest that the
  behavior of non-MCs is similar to that of the DL shocks and different
  from that of MCs. In other words, the CHs may deflect the CMEs away
  from the Sun-Earth line and force them to behave like limb CMEs with
  DL shocks. This finding supports the idea that all CMEs may be flux
  ropes if viewed from an appropriate vantage point.

---------------------------------------------------------
Title: CME Parameter Input to ENLIL: LASCO halo cone versus STEREO
    measurements
Authors: St Cyr, O. C.; Orlove, M.; Xie, H.; Gilbert, H. R.; Odstrcil,
   D.; Gopalswamy, N.; Mays, M. L.; Quirk, C. A.; Henning, C.
2011AGUFMSH33B2046S    Altcode:
  ENLIL is a well-known model in the solar-helio community (Odstrcil
  and Pizzo, 1999) and is frequently used to predict the arrival of
  coronal mass ejections (CMEs) at Earth based on observations from
  the SOHO LASCO coronagraphs. The halo CME parameters needed to drive
  ENLIL are the CME size, speed, and direction, and these are typically
  derived from fitting a "cone model" to the LASCO CME images to drive
  interplanetary disturbances through the inner heliosphere (Xie et al.,
  2004). But as seen from a single vantage point along the Sun-Earth
  line, it is difficult to determine these projected CME parameters
  unambiguously (e.g., Gopalswamy et al., 2009). Over the past few years
  we have been in the fortunate circumstance of having the twin STEREO
  spacecraft (Kaiser et al., 2008) at quadrature with the Sun-Earth line,
  so we can compare directly the validity of the cone model with actual
  measurements of the CMEs heading toward Earth. We report here on a
  comparison of more than twenty SOHO LASCO halo coronal mass ejections
  that were also observed by STEREO between 2008 and mid-2011.

---------------------------------------------------------
Title: What Controls the Magnetic Field Configuration of
    Interplanetary Coronal Mass Ejections ?
Authors: Moon, Y.; Gopalswamy, N.; Kim, R.; Xie, H.; Yashiro, S.
2011AGUFMSH51A1994M    Altcode:
  In this work we address the question of the classification of
  interplanetary coronal mass ejections (ICMEs): magnetic cloud (MC)
  or ejecta (EJ). Using 186 shock-associated ICMEs from 1997 to 2006,
  we have examined three possible causes : (1) magnetic complexity
  characterized by sunspot number, (2) CME direction characterized by
  CME angular distance (the angle between the CME cone axis and the sky
  plane), and (3) CME-CME interaction characterized by the number of
  halo CMEs. First, the annual fraction of MC is poorly anti-correlated
  (R=-0.36) with annual sunspot number. Second, more than half of
  the CMEs that originated near the central meridian produced EJs
  and the distribution of CME angular distance for 38 EJs is not much
  different from that for 16 MCs. Third, the annual fraction of MC is
  well anti-correlated (R=-0.78) with the annual number of halo CMEs. In
  addition, we also searched for candidate of interacting CMEs according
  to temporal and spatial closeness by considering all halo CMEs during
  the same period. As a result, we find that the annual fraction of
  interacting CMEs is well correlated (R=0.87) with the annual number
  of the halo CMEs as well as anti-correlated (R=-0.85) with the annual
  fraction of MCs. The contingency table between CME-CME interaction
  and MC occurrence also shows a good statistical result (Prediction of
  detection 'yes' is 0.88, and Critical Success Index is 0.62), which
  is better than that for the halo CME-storm relationship. Our results
  imply that the CME interaction is mainly responsible for their observed
  structure (MC or EJ) in the interplanetary medium.

---------------------------------------------------------
Title: CME Productivity of Active Regions 11158 and 11166
Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.; Makela, P. A.
2011AGUFMSH13B1965Y    Altcode:
  Active regions (ARs) 11158 and 11166 respectively produced an X-class
  flare on 2011 Feb 15 and March 9. The former flare was associated with
  a CME, but the latter one was not. We examined the CME productivity
  of the two active regions. AR 11158 emerged at around 3 UT on 2011 Feb
  10. The first major flare from the active region was the M6.6 flare at
  17:28 on Feb 13 which was associated with a CME. The CME productivity
  was very high on Feb 14 and 15. Out of 11 flares (&gt;C3 level),
  10 had an associated CMEs. The CME productivity suddenly dropped on
  Feb 18. There were 2 M- and 4 C-class flares but none of them had
  an associated CME. AR 11166 emerged on Feb 25 on the far side of the
  Sun and appeared on the east limb on March 2. One X-, four M-, and 16
  upper C-class (C3-C9) flares occurred during the disk passage. The CME
  productivity of the AR was not low since 11 out of 20 M- and C-class
  flares had an associated CME. The X1.5 flare lacking an associated CME
  is very special in terms of the CME productivity of the AR 11166. We
  discuss the reason why the X flare lacked a CME.

---------------------------------------------------------
Title: Type II Radio Bursts as an Indicator of CME Location
Authors: Quirk, C. A.; St Cyr, O. C.; Henning, C.; Xie, H.; Gilbert,
   H. R.; Orlove, M.; Gopalswamy, N.; Odstrcil, D.
2011AGUFMSH33B2047Q    Altcode:
  We examined a subset of nine low-frequency radio events with type
  II radio bursts that drifted below 2 megahertz and were detected by
  the WAVES investigation on the WIND spacecraft. For each event,
  we identified the associated coronal mass ejection (CME) and
  derived the electron density using a model of solar wind plasma
  frequency (f<SUB>p</SUB> ≈ 9 * n<SUB>e</SUB><SUP>1/2</SUP>, where
  f<SUB>p</SUB> is plasma frequency in kHz and n<SUB>e</SUB> is electron
  density in cm<SUP>-3</SUP>) . We also used the pb_inverter program
  in SolarSoft developed by Howard and Hayes to examine the electron
  density structure. Expanding on the Van De Hulst process of inverting
  polarized brightness measurements, the program inverts total brightness
  measurements from SOHO LASCO images to extract electron density
  information. From the electron density inferred from radio spectra,
  we derived the location of the CME using five standard electron density
  to height models (Leblanc, 1996; Saito, 1977; Bougeret, 1984; Alvarez,
  1973; and Fainberg, 1971). Using images from the LASCO instrument on
  SOHO and the SECCHI instrument on STEREO, we extracted locations of
  the leading edge of the CME and compared the heights and velocities to
  those found using the frequency data. For the lowest frequency events,
  we also compared our results to the outputs of ENLIL, a time-dependent,
  three-dimensional, MHD model of the heliosphere hosted by the Community
  Coordinated Modeling Center (CCMC) at NASA Goddard Space Flight Center.

---------------------------------------------------------
Title: Location of Coronal and IP Type II Burst Source Regions from
    Radio and White-light Observations
Authors: Makela, P. A.; Gopalswamy, N.; Yashiro, S.
2011AGUFMSH23A1947M    Altcode:
  We present our preliminary results on the locations of source regions
  of the type II radio bursts in the metric (m) and dekameter-hectometric
  (DH) wavelength range. Type II bursts are occasionally observed to
  consist of two temporally overlapping lanes of metric and DH bursts. It
  has been suggested that the DH-component could be associated with
  a CME-driven shock and the m-component with a blast wave or unknown
  source, or that the DH-component originates from the shock nose and
  the m-component from the shock flanks. In our study we used time-height
  measurements of the associated coronal mass ejections (CMEs) to estimate
  speeds at various position angles (PAs) along the CME front. We also
  estimated plasma densities at the same PAs in the corona from inversion
  of polarized brightness (pB) images of SOHO/LASCO coronagraphs. These
  measurements suggest that both the m and DH-components can be explained
  reasonably well with a single CME-driven shock as their source.

---------------------------------------------------------
Title: Earth-Affecting Solar Causes Observatory (EASCO): A
    Heliophysics Mission at the Sun-Earth L5
Authors: Gopalswamy, N.; Easco Team
2011AGUFMSH22A..04G    Altcode:
  The wealth of knowledge accumulated on coronal mass ejections
  over the past decade primarily comes from the SOHO and
  STEREO missions. Unfortunately, these missions lacked some key
  measurements. For example, STEREO did not have a magnetograph and SOHO
  did not have an in-situ magnetometer. From the Sun-Earth line, SOHO
  was not well-suited for observing Earth-directed CMEs because of the
  occulting disk. STEREO's angle with the Sun-Earth line is changing
  constantly, so only a limited number of Earth-directed CMEs were
  observed in profile. The next generation Heliophysics mission should
  overcome these deficiencies and observe the Sun from a vantage point
  different from the Sun-Earth line. The Sun-Earth Lagrange point L5 is
  well suited for stationing such a mission. Such a mission would provide
  broad-side view of Earth directed CMEs and the shocks if the CMEs
  are fast enough. Additionally, corotating interaction regions (CIRs),
  which also cause adverse space weather, first arrive at L5 and a few
  days later at Earth, thus providing excellent prediction opportunity
  based on in-situ measurements at L5. Solar sources (active regions,
  coronal holes) of these large-scale disturbances can be observed more
  than a week before they rotate to Earth View. A suite of ten instruments
  (seven remote-sensing in X-ray, EUV, optical, and radio wavelengths
  and 3 in situ for plasma, magnetic field, and energetic particles)
  would constitute an ideal scientific payload. Recently an L5 mission
  concept known as the Earth-Affecting Solar Causes Observatory (EASCO)
  (Gopalswamy et al., 2011) was studied at the Mission Design Laboratory
  (MDL) of NASA's Goddard Space Flight Center. The aim of the MDL study
  was to see how the scientific payload consisting of ten instruments
  can be accommodated in the spacecraft bus, what propulsion system can
  transfer the payload to the Sun-Earth L5, and what launch vehicles
  are appropriate. The study found that all the ten instruments can be
  readily accommodated and can be launched using an intermediate size
  vehicle such as Taurus II with enhanced faring. The study also found
  that a hybrid propulsion system consisting of an ion thruster (using
  ~55 kg of Xenon) and hydrazine (~10 kg) is adequate to position the
  spacecraft at L5. The transfer to L5 will take about 2 years and the
  science mission will last for 4 years around the next solar maximum in
  2025. The mission can be readily extended for another solar cycle to get
  a solar-cycle worth of data on Earth-affecting CMEs and CIRs. This paper
  describes the EASCO mission, the scientific payload, and the results of
  the MDL study. Reference: Gopalswamy, N. et al., Earth-Affecting Solar
  Causes Observatory (EASCO): A potential International Living with a
  Star Mission from Sun-Earth L5, J. Atmospheric and Solar-Terrestrial
  Physics, 73, 658, 2011

---------------------------------------------------------
Title: First direct observational evidence of a CME deflection by
    coronal hole on 15 February 2011 and a comparison with computations
Authors: Mohamed, A. A.; Gopalswamy, N.
2011AGUFMSH23A1950M    Altcode:
  It has been shown that coronal holes (CHs) can deflect a coronal
  mass ejection (CME) away or towards the Sun-Earth line depending on
  their relative location (Gopalswamy et al., 2009). This effect can be
  described using a coronal-hole influence parameter (CHIP), which depends
  on the CH area, the distance between the CH and the eruption region, and
  the magnetic field strength within the CH at the photospheric level. We
  have direct observation of CME deflection during the 2011February 15
  CME, which was associated with an X2.2 flare (S21W21) on 01:44 UT from
  STEREO/COR1 and COR2 observations. The CHIP is computed for the 2011
  February 15 CME to be 0.73 G with a deflection angle of 62o. We use
  the 193 Å AIA image from the Solar Dynamics Observatory (SDO) for CH
  identification and SDO/HMI for determining the magnetic field strength
  inside the CH. The largest CH (centroid at S59W15)) was close to the
  CME eruption region (S21W21). We measured the deflection angle as 38o,
  using STEREO/COR2 images. This deflection angle is not too different
  from that obtained from the coronal hole observations.

---------------------------------------------------------
Title: High Angular Resolution Imaging of Solar Radio Bursts from
    the Lunar Surface
Authors: MacDowall, R. J.; Lazio, J.; Bale, S.; Burns, J. O.; Farrell,
   W. M.; Gopalswamy, N.; Jones, D. L.; Kasper, J. C.; Weiler, K.
2011AGUFM.P13D1738M    Altcode:
  Locating low frequency radio observatories on the lunar surface has a
  number of advantages, including positional stability and a very low
  ionospheric radio cutoff. Here, we describe the Radio Observatory
  on the Lunar Surface for Solar studies (ROLSS), a concept for a low
  frequency, radio imaging interferometric array designed to study
  particle acceleration in the corona and inner heliosphere. ROLSS
  would be deployed during an early lunar sortie or by a robotic
  rover as part of an unmanned landing. The preferred site is on
  the lunar near side to simplify the data downlink to Earth. The
  prime science mission is to image type II and type III solar radio
  bursts with the aim of determining the sites at and mechanisms by
  which the radiating particles are accelerated. Secondary science
  goals include constraining the density of the lunar ionosphere by
  measuring the low radio frequency cutoff of the solar radio emissions
  or background galactic radio emission, measuring the flux, particle
  mass, and arrival direction of interplanetary and interstellar dust,
  and constraining the low energy electron population in astrophysical
  sources. Furthermore, ROLSS serves a pathfinder function for larger
  lunar radio arrays. Key design requirements on ROLSS include the
  operational frequency and angular resolution. The electron densities
  in the solar corona and inner heliosphere are such that the relevant
  emission occurs below 10 MHz, essentially unobservable from Earth's
  surface due to the terrestrial ionospheric cutoff. Resolving the
  potential sites of particle acceleration requires an instrument with
  an angular resolution of at least 2 deg at 10 MHz, equivalent to a
  linear array size of approximately one kilometer. The major components
  of the ROLSS array are 3 antenna arms, each of 500 m length, arranged
  in a Y formation, with a central electronics package (CEP) at their
  intersection. Each antenna arm is a linear strip of polyimide film
  (e.g., Kapton) on which 16 single polarization dipole antennas are
  located by depositing a conductor (e.g., silver). The arms also contain
  transmission lines for carrying the radio signals from the science
  antennas to the CEP. Operations would consist of data acquisition during
  the lunar day, with data downlinks to Earth one or more times every
  24 hours. This work is supported in part by the NASA Lunar Science
  Institute via Cooperative Agreement NNA09DB30A with the LUNAR team.

---------------------------------------------------------
Title: From SOHO to STEREO: Understanding Propagation of Coronal
    Mass Ejections
Authors: Gopalswamy, N.
2011AGUFMSH32A..08G    Altcode:
  Direct comparison between coronal mass ejections (CMEs) from near the
  Sun and their solar wind counterparts became possible roughly a decade
  after the discovery of CMEs (Lindsay et al. 1999). This comparison
  revealed that fast CMEs decelerate and slow CMEs accelerate due
  to the interaction with the solar wind. Gopalswamy et al. (2000)
  quantified this interaction as an interplanetary acceleration
  which is useful in predicting the arrival time and speed of CMEs
  at 1 AU. The interplanetary acceleration is essentially due to the
  aerodynamic drag between the CME and the solar wind because the
  propelling force and the solar gravity are effective only near the
  Sun. Combined remote-sensing and in situ observations from SOHO and
  Wind/ACE have helped us estimate the influence of the solar wind on
  the propagation of CMEs. However, these measurements have severe
  limitations because the remote-sensed and in-situ observations
  correspond to different portions of the CME. Furthermore, the true
  speeds of Earth-directed CMEs cannot be measured accurately from a
  spacecraft located along the Sun-Earth line. There have been attempts
  to model the CME as a cone and get the space speed of the CME, which
  did improve the travel time predictions. Instruments on board the
  Solar Terrestrial Relations Observatory (STEREO) mission were able
  to provide observations of Earth-arriving CMEs without projection
  effects, while the same CMEs were observed at Sun-Earth L1 by Wind
  and ACE spacecraft. The quadrature between STEREO and L1 spacecraft
  presented an ideal situation to study the interplanetary evolution of
  CMEs and test earlier model results. The quadrature observations did
  improve the CME travel time predictions, but additional factors such
  as the unusually slow solar wind, CME cannibalism, and coronal-hole
  deflection need to be considered to reconcile the difference between
  observed and predicted travel times. This point is illustrated using the
  2011 February 15 CME. References Gopalswamy, N. et al., Interplanetary
  acceleration of coronal mass ejections, Geophys. Res. Lett., 27, 145,
  2000 Lindsay, G. et al., Relationships between coronal mass ejection
  speeds from coronagraph images and interplanetary characteristics of
  associated interplanetary coronal mass ejections, J. Geophys. Res.,
  104, 12515, 1999

---------------------------------------------------------
Title: The Effects of Coronal Holes on the Time Profiles of Gradual
    Solar Energetic Particle Events
Authors: Kahler, S. W.; Akiyama, S.; Gopalswamy, N.
2011AGUFMSH44A..06K    Altcode:
  The onset times and peak intensities of solar energetic particle (SEP)
  events at Earth have long been thought to be influenced by the open
  magnetic fields of coronal holes (CHs). The basic idea is that when
  CHs lie between the solar SEP source region and the interplanetary
  magnetic field lines connecting the Earth to the Sun, there will be
  a delay in onset and/or a diminution in the peak intensity of the SEP
  event. Shen et al.(2006) found that neither CH proximity nor CH relative
  location produced any obvious effect on SEP peak intensities. However,
  Gopalswamy et al.(2009) have used SOHO/EIT CHs and a defined CH
  influence parameter to show that nearby CHs can deflect fast CMEs
  from their expected directions in space, explaining the appearance
  of driverless shocks at 1 AU from CMEs ejected near solar central
  meridian. Recent work has looked at the relation between CHs and CMEs
  over the rise, maximum, and declining phases of solar cycle 23. Here we
  use the CH locations and influence parameters to examine the effects of
  CHs on the timing and intensities of SEP events observed by the GOES and
  Wind spacecraft. We also include cases of fast CMEs that drive shocks
  but produce no or only weak SEP events at Earth. The goal is to use CH
  locations to help predict the SEP events produced by fast and wide CMEs.

---------------------------------------------------------
Title: The Radio Observatory on the Lunar Surface for Solar studies
Authors: Lazio, T. Joseph W.; MacDowall, R. J.; Burns, Jack O.; Jones,
   D. L.; Weiler, K. W.; Demaio, L.; Cohen, A.; Paravastu Dalal, N.;
   Polisensky, E.; Stewart, K.; Bale, S.; Gopalswamy, N.; Kaiser, M.;
   Kasper, J.
2011AdSpR..48.1942L    Altcode:
  The Radio Observatory on the Lunar Surface for Solar studies (ROLSS) is
  a concept for a near-side low radio frequency imaging interferometric
  array designed to study particle acceleration at the Sun and in the
  inner heliosphere. The prime science mission is to image the radio
  emission generated by Type II and III solar radio burst processes
  with the aim of determining the sites at and mechanisms by which
  the radiating particles are accelerated. Specific questions to be
  addressed include the following: (1) Isolating the sites of electron
  acceleration responsible for Type II and III solar radio bursts
  during coronal mass ejections (CMEs); and (2) Determining if and the
  mechanism(s) by which multiple, successive CMEs produce unusually
  efficient particle acceleration and intense radio emission. Secondary
  science goals include constraining the density of the lunar ionosphere
  by searching for a low radio frequency cutoff to solar radio emission
  and constraining the low energy electron population in astrophysical
  sources. Key design requirements on ROLSS include the operational
  frequency and angular resolution. The electron densities in the solar
  corona and inner heliosphere are such that the relevant emission occurs
  at frequencies below 10 MHz. Second, resolving the potential sites of
  particle acceleration requires an instrument with an angular resolution
  of at least 2°, equivalent to a linear array size of approximately
  1000 m. Operations would consist of data acquisition during the lunar
  day, with regular data downlinks. No operations would occur during
  lunar night. ROLSS is envisioned as an interferometric array, because
  a single aperture would be impractically large. The major components
  of the ROLSS array are 3 antenna arms arranged in a Y shape, with
  a central electronics package (CEP) located at the center. The Y
  configuration for the antenna arms both allows for the formation of
  reasonably high dynamic range images on short time scales as well
  as relatively easy deployment. Each antenna arm is a linear strip
  of polyimide film (e.g., Kapton™) on which 16 science antennas are
  located by depositing a conductor (e.g., silver). The antenna arms can
  be rolled for transport, with deployment consisting of unrolling the
  rolls. Each science antenna is a single polarization dipole. The arms
  also contain transmission lines for carrying the radio signals from
  the science antennas to the CEP. The CEP itself houses the receivers
  for the science antennas, the command and data handling hardware,
  and, mounted externally, the downlink antenna. We have conducted
  two experiments relevant to the ROLSS concept. First, we deployed a
  proof-of-concept science antenna. Comparison of the impedance of the
  antenna feed points with simulations showed a high level of agreement,
  lending credence to the antenna concept. Second, we exposed a sample
  of space-qualified polyimide film, with a silver coating on one side,
  to temperature cycling and UV exposure designed to replicate a year on
  the lunar surface. No degradation of the polyimide film's material or
  electric properties was found. Both of these tests support the notion of
  using polyimide-film based antennas. The prime science mission favors an
  equatorial site, and a site on the limb could simplify certain aspects
  of the instrument design. A site on the lunar near side is sufficient
  for meeting the science goals. While the site should be of relatively
  low relief topography, the entire site does not have to be flat as
  the fraction of the area occupied by the antenna arms is relatively
  small (∼0.3%). Further, the antenna arms do not have to lay flat
  as deviations of ±1 m are still small relative to the observational
  wavelengths. Deployment could be accomplished either with astronauts,
  completely robotically, or via a combination of crewed and robotic
  means. Future work for the ROLSS concept includes more exhaustive
  testing of the radio frequency (RF) and environmental suitability of
  polyimide film-based science antennas, ultra-low power electronics in
  order to minimize the amount of power storage needed, batteries with
  a larger temperature range for both survival and operation, and rovers
  (robotic, crewed, or both) for deployment. The ROLSS array could also
  serve as the precursor to a larger array on the far side of the Moon
  for astrophysical and cosmological studies.

---------------------------------------------------------
Title: Understanding Shock Dynamics in the Inner Heliosphere with
Modeling and Type II Radio Data: the 2010-04-03 event
Authors: Xie, H.; Odstrcil, D.; Mays, M. L.; St Cyr, O. C.; Gopalswamy,
   N.; Cremades, H.
2011AGUFMSH33B2050X    Altcode:
  The 2010 April 03 solar event was studied using observations from
  STEREO A and B SECCHI, SOHO LASCO, and kilometric type II data
  combined with the WSA-Cone-ENLIL model. In particular, we identified
  the origin of the coronal mass ejection (CME) using STEREO EUVI
  and SOHO EIT images. A flux-rope model fit to the SECCHI A and B,
  and LASCO images were used to determine the CME's direction, size,
  and actual speed. J-maps from STEREO COR2/HI-1/HI-2 and simulations
  from the ENLIL model were used to study the formation and evolution of
  the shock in the inner heliosphere. In addition, we also studied the
  time-distance profile of the shock propagation from kilometric type II
  (kmTII) radio burst observations. Here we report on a comparison of
  two methods of predicting interplanetary shock arrival time: the ENLIL
  model and the kmTII method; and investigate whether or not using the
  ENLIL model density improves the kmTII rediction. We found that the
  ENLIL model predicted the kinematics of shock evolution well. The shock
  arrival times (SAT) and linear fit shock velocities in the ENLIL model
  agreed well with those measurements in the J-maps along both the CME
  leading edge and the Sun-Earth line. The model also reproduced most
  of the large scale structures of the shock propagation and gave the
  SAT prediction at Earth with an error of 1.5 hours. The kmTII method
  predicted the SAT at Earth with an error of 8 hours when using the
  ENLIL model plasma density at near Earth; but it improved to 3 hours
  when using the model density near the CME leading edge at 1 AU.

---------------------------------------------------------
Title: Magnetic field strength in the upper solar corona using
    white-light shock structures surrounding coronal mass ejections
Authors: Kim, R.; Gopalswamy, N.; Moon, Y.; Cho, K.; Yashiro, S.
2011AGUFMSH43B1955K    Altcode:
  To measure the magnetic field strength in the solar corona, we examined
  12 fast (&gt; 1000 km s-1) limb CMEs which show clear shock-like
  structures in SOHO/LASCO observations. By applying piston-shock
  relationship to the observed CME's standoff distance and electron
  density compression ratio, we estimated the Mach number, Alfven speed,
  and magnetic field strength in the height range 3 to 15 solar radii
  (Rs). We found: (1) the standoff distance observed in the solar corona
  is consistent with those from a magnetohydrodynamic (MHD) model and
  near-Earth observations; (2) the Mach number as a shock strength is
  in the range 1.49 to 3.52 from the standoff distance data, but when
  we use the compression ratio, the Mach number is in the range 1.47 to
  1.90, implying that the measured density compression ratio is likely
  to be underestimated due to observational limit; (3) the Alfven speed
  ranges from 259 to 982 km s-1 and the magnetic field strength is in
  the range 6 to 120 mG when the standoff distance is used; (4) if we
  multiply the density compression ratio by a factor of 2, the Alfven
  speeds and the magnetic field strengths are consistent in both methods;
  (5) the magnetic field strengths derived from the shock parameters are
  similar to those of empirical models and previous estimates. This is a
  new attempt to measure magnetic field strength in the upper corona up
  to 15 Rs from coronagraph observations alone. Our observations support
  the idea that the diffuse structures surrounding the CME front can be
  interpreted as shock structures.

---------------------------------------------------------
Title: Determination of the heliospheric radial magnetic field from
    the Standoff Distance of a CME-driven shock Observed by the STEREO
    spacecraft
Authors: Poomvises, W.; Gopalswamy, N.; Yashiro, S.
2011AGUFMSH23A1948P    Altcode:
  Recent work by Gopalswamy and Yashiro (2011) determined the radial
  coronal magnetic field strength from 6 to 23 solar radii (Rs) by
  measuring the standoff distance of a CME-driven shock observed in the
  coronagraphic field of view. We now extend their work to determine
  radial magnetic field strength in the heliocentric distance range
  6 - 100 Rs using data from COR2 and HI 1 instruments onboard the
  STEREO spacecraft. We apply the Raytrace model (Thernisien 2006,
  2009) to measure the shock standoff distance for the April 5, 2008
  CME. In addition, we determine the flux rope curvature by fitting a
  circle to the CME. The ratio of the standoff distance to the radius of
  curvature is a known function of the shock Mach number and the adiabatic
  index. Thus we can obtain the shock Mach number, assuming the value
  of the adiabatic index. The Alfven velocity can then be calculated
  using the ambient solar wind velocity, shock velocity obtained
  from the height-time measurements, and the Mach number. Finally,
  the radial magnetic field trength is computed from the Alfven speed
  and the density of the ambient medium. We also compare the derived
  magnetic field strength with the in-situ measurements made by the
  Helios spacecraft, which measured the magnetic field in the distance
  range 60 - 215 Rs. We found that the magnetic field strength decreases
  from 17 mG at 6 Rs to 1 mG at 100 Rs. In addition, the radial profile
  can be described by a power law.

---------------------------------------------------------
Title: United Nations Basic Space Science Initiative: 2010 Status
    Report on the International Space Weather Initiative
Authors: Gadimova, S.; Haubold, H. J.; Danov, D.; Georgieva, K.;
   Maeda, G.; Yumoto, K.; Davila, J. M.; Gopalswamy, N.
2011SunGe...6....7G    Altcode: 2011arXiv1108.2247G
  The UNBSSI is a long-term effort for the development of astronomy
  and space science through regional and international cooperation in
  this field on a worldwide basis. A series of workshops on BSS was
  held from 1991 to 2004 (India 1991, Costa Rica and Colombia 1992,
  Nigeria 1993, Egypt 1994, Sri Lanka 1995, Germany 1996, Honduras
  1997, Jordan 1999, France 2000, Mauritius 2001, Argentina 2002, and
  China 2004) Pursuant to resolutions of the United Nations Committee
  on the Peaceful Uses of Outer Space (UNCOPUOS) and its Scientific
  and Technical Subcommittee, since 2005, these workshops focused on
  the International Heliophysical Year 2007 (UAE 2005, India 2006,
  Japan 2007, Bulgaria 2008, Ro Korea 2009) Starting in 2010, the
  workshops focus on the International Space Weather Initiative (ISWI)
  as recommended in a three-year-work plan as part of the deliberations
  of UNCOPUOS (www.iswi-secretariat.org/). Workshops on the ISWI have
  been scheduled to be hosted by Egypt in 2010 for Western Asia, Nigeria
  in 2011 for Africa, and Ecuador in 2012 for Latin America and the
  Caribbean. Currently, fourteen IHY/ISWI instrument arrays with more
  than five hundred instruments are operational in ninety countries.

---------------------------------------------------------
Title: Relation Between the 3D-Geometry of the Coronal Wave and
    Associated CME During the 26 April 2008 Event
Authors: Temmer, M.; Veronig, A. M.; Gopalswamy, N.; Yashiro, S.
2011SoPh..273..421T    Altcode: 2011SoPh..tmp...75T; 2011arXiv1103.0196T; 2011SoPh..tmp..227T;
   2011SoPh..tmp..158T
  We study the kinematical characteristics and 3D geometry of a
  large-scale coronal wave that occurred in association with the 26
  April 2008 flare-CME event. The wave was observed with the EUVI
  instruments aboard both STEREO spacecraft (STEREO-A and STEREO-B)
  with a mean speed of ∼ 240 km s<SUP>−1</SUP>. The wave is more
  pronounced in the eastern propagation direction, and is thus, better
  observable in STEREO-B images. From STEREO-B observations we derive
  two separate initiation centers for the wave, and their locations fit
  with the coronal dimming regions. Assuming a simple geometry of the
  wave we reconstruct its 3D nature from combined STEREO-A and STEREO-B
  observations. We find that the wave structure is asymmetric with an
  inclination toward East. The associated CME has a deprojected speed
  of ∼ 750±50 km s<SUP>−1</SUP>, and it shows a non-radial outward
  motion toward the East with respect to the underlying source region
  location. Applying the forward fitting model developed by Thernisien,
  Howard, and Vourlidas (Astrophys. J. 652, 763, 2006), we derive the
  CME flux rope position on the solar surface to be close to the dimming
  regions. We conclude that the expanding flanks of the CME most likely
  drive and shape the coronal wave.

---------------------------------------------------------
Title: Earth-Affecting Solar Causes Observatory (EASCO): a mission
    at the Sun-Earth L5
Authors: Gopalswamy, Nat; Davila, Joseph M.; Auchère, Frédéric;
   Schou, Jesper; Korendyke, Clarence M.; Shih, Albert; Johnston, Janet
   C.; MacDowall, Robert J.; Maksimovic, Milan; Sittler, Edward; Szabo,
   Adam; Wesenberg, Richard; Vennerstrom, Suzanne; Heber, Bernd
2011SPIE.8148E..0ZG    Altcode: 2011SPIE.8148E..30G; 2011arXiv1109.2929G
  Coronal mass ejections (CMEs) and corotating interaction regions
  (CIRs) as well as their source regions are important because of
  their space weather consequences. The current understanding of CMEs
  primarily comes from the Solar and Heliospheric Observatory (SOHO)
  and the Solar Terrestrial Relations Observatory (STEREO) missions,
  but these missions lacked some key measurements: STEREO did not have a
  magnetograph; SOHO did not have in-situ magnetometer. SOHO and other
  imagers such as the Solar Mass Ejection Imager (SMEI) located on the
  Sun-Earth line are also not well-suited to measure Earth-directed
  CMEs. The Earth-Affecting Solar Causes Observatory (EASCO) is a
  proposed mission to be located at the Sun-Earth L5 that overcomes
  these deficiencies. The mission concept was recently studied at the
  Mission Design Laboratory (MDL), NASA Goddard Space Flight Center,
  to see how the mission can be implemented. The study found that the
  scientific payload (seven remote-sensing and three in-situ instruments)
  can be readily accommodated and can be launched using an intermediate
  size vehicle; a hybrid propulsion system consisting of a Xenon ion
  thruster and hydrazine has been found to be adequate to place the
  payload at L5. Following a 2-year transfer time, a 4-year operation
  is considered around the next solar maximum in 2025.

---------------------------------------------------------
Title: Coronal magnetic field measurement using CME-driven shock
    observations
Authors: Gopalswamy, N.; Nitta, N.; Yashiro, S.; Mäkelä, P.; Xie,
   H.; Akiyama, S.
2011sdmi.confE..22G    Altcode:
  Collisionless shocks form ahead of coronal mass ejections (CMEs) when
  the CME speed exceeds the Alfven speed of the ambient plasma in the
  corona and interplanetary medium. The shock stands at a distance from
  the CME flux rope that depends on the shock Mach number, the geometry
  of the driver, and the adiabatic index. While the shock ahead of the
  CME has been observed for a long time in the in situ data, it has
  been identified recently near the Sun in the coronagraphic and EUV
  images. Unlike in situ observations, the imaging observations are two
  dimensional, so one can better discern the CME-shock relationship
  near the Sun. Gopalswamy and Yashiro (2011) demonstrated that the
  coronal magnetic field can be derived from the shock standoff distance
  measured in coronagraphic images. The method involves measuring the
  standoff distance, the radius of curvature of the flux rope, and
  assuming the value of the adiabatic index and deriving the Alfvénic
  Mach number. The next step is to derive the Alfvénic Mach number
  from the measured shock speed and an estimate of the local solar
  wind speed. The final step involves deriving the magnetic field from
  the Alfven speed by measuring the local plasma density either from
  coronagraphic (polarized brightness) images (Gopalswamy and Yashiro
  2011) or from the band-splitting of type II radio bursts (Gopalswamy
  et al., 2011). In this paper, we derive the combined magnetic field
  profile from near the Sun to the edge of the LASCO field of view
  (1.5 to 30 solar radii) and compare it with the current model profiles.

---------------------------------------------------------
Title: Energetic storm particle events in coronal mass ejection-driven
    shocks
Authors: Mäkelä, P.; Gopalswamy, N.; Akiyama, S.; Xie, H.;
   Yashiro, S.
2011JGRA..116.8101M    Altcode:
  We investigate the variability in the occurrence of energetic storm
  particle (ESP) events associated with shocks driven by coronal mass
  ejections (CMEs). The interplanetary shocks were detected during
  the period from 1996 to 2006. First, we analyze the CME properties
  near the Sun. The CMEs with an ESP-producing shock are faster
  ($\langle$V<SUB>CME</SUB>$\rangle$ = 1088 km/s) than those driving
  shocks without an ESP event ($\langle$V<SUB>CME</SUB>$\rangle$ = 771
  km/s) and have a larger fraction of halo CMEs (67% versus 38%). The
  Alfvénic Mach numbers of shocks with an ESP event are on average 1.6
  times higher than those of shocks without. We also contrast the ESP
  event properties and frequency in shocks with and without a type II
  radio burst by dividing the shocks into radio-loud (RL) and radio-quiet
  (RQ) shocks, respectively. The shocks seem to be organized into a
  decreasing sequence by the energy content of the CMEs: RL shocks with an
  ESP event are driven by the most energetic CMEs, followed by RL shocks
  without an ESP event, then RQ shocks with and without an ESP event. The
  ESP events occur more often in RL shocks than in RQ shocks: 52% of RL
  shocks and only ∼33% of RQ shocks produced an ESP event at proton
  energies above 1.8 MeV; in the keV energy range the ESP frequencies
  are 80% and 65%, respectively. Electron ESP events were detected in
  19% of RQ shocks and 39% of RL shocks. In addition, we find that (1)
  ESP events in RQ shocks are less intense than those in RL shocks; (2)
  RQ shocks with ESP events are predominately quasi-perpendicular shocks;
  (3) their solar sources are located slightly to the east of the central
  meridian; and (4) ESP event sizes show a modest positive correlation
  with the CME and shock speeds. The observation that RL shocks tend
  to produce more frequently ESP events with larger particle flux
  increases than RQ shocks emphasizes the importance of type II bursts
  in identifying solar events prone to producing high particle fluxes
  in the near-Earth space. However, the trend is not definitive. If
  there is no type II emission, an ESP event is less likely but not
  absent. The variability in the probability and size of ESP events
  most likely reflects differences in the shock formation in the low
  corona and changes in the properties of the shocks as they propagate
  through interplanetary space and the escape efficiency of accelerated
  particles from the shock front.

---------------------------------------------------------
Title: The Strength and Radial Profile of the Coronal Magnetic Field
    from the Standoff Distance of a Coronal Mass Ejection-driven Shock
Authors: Gopalswamy, Nat; Yashiro, Seiji
2011ApJ...736L..17G    Altcode: 2011arXiv1106.4832G
  We determine the coronal magnetic field strength in the heliocentric
  distance range 6-23 solar radii (Rs) by measuring the shock
  standoff distance and the radius of curvature of the flux rope
  during the 2008 March 25 coronal mass ejection imaged by white-light
  coronagraphs. Assuming the adiabatic index, we determine the Alfvén
  Mach number, and hence the Alfvén speed in the ambient medium using
  the measured shock speed. By measuring the upstream plasma density
  using polarization brightness images, we finally get the magnetic field
  strength upstream of the shock. The estimated magnetic field decreases
  from ~48 mG around 6 Rs to 8 mG at 23 Rs. The radial profile of the
  magnetic field can be described by a power law in agreement with other
  estimates at similar heliocentric distances.

---------------------------------------------------------
Title: First direct observational evidence of a CME deflection by
    coronal hole on 15 February 2011 and a comparison with computations
Authors: Mohamed, Amaal Abd-Alla; Gopalswamy, Nat
2011shin.confE.127M    Altcode:
  It has been shown that coronal holes (CHs) can deflect a coronal
  mass ejection (CME) away or towards the Sun-Earth line depending on
  their relative location (Gopalswamy et al., 2009). This effect can be
  described using a coronal-hole influence parameter (CHIP), which depends
  on the CH area, the distance between the CH and the eruption region, and
  the magnetic field strength within the CH at the photospheric level. We
  have direct observation of CME deflection during the 2011February 15
  CME, which was associated with an X2.2 flare (S21W21) on 01:44 UT from
  STEREO/COR1 and COR2 observations. The CHIP is computed for the 2011
  February 15 CME to be 0.73 G with a deflection angle of 62o. We use
  the 193 Å AIA image from the Solar Dynamics Observatory (SDO) for CH
  identification and SDO/HMI for determining the magnetic field strength
  inside the CH. The largest CH (centroid at S59W15)) was close to the
  CME eruption region (S21W21). We measured the deflection angle as 38o,
  using STEREO/COR2 images. This deflection angle is not too different
  from that obtained from the coronal hole observations.

---------------------------------------------------------
Title: Halo CMEs: Comparing Observations and Models
Authors: Gilbert, Holly; St. Cyr, Matthew Orlove. C.; Xie, Hong;
   Mays, Leila; Gopalswamy, N.; Quirk, Cori; Henning, Christina
2011shin.confE..49G    Altcode:
  Since 1996, the SOHO LASCO coronagraphs have detected 'halo' CMEs
  that appear to be directed toward Earth, but information about the
  size and speed of these events seen face-on has been limited. From a
  single vantage point along the Sun-Earth line, the primary limitation
  has been ambiguity in fitting the cone model (or other forward-modeling
  techniques, e.g., Thernisian et al., 2006). But in the past few years,
  the STEREO mission has provided a view of Earth-directed events from
  the side. These events offer the opportunity to compare measurements
  (width and speed) of halo CMEs observed by STEREO with models that
  derive halo CME properties. We report here results of such a comparison
  on a large sample of LASCO CMEs in the STEREO era

---------------------------------------------------------
Title: Effects of Refraction on Angles and Times of Arrival of Solar
    Radio Bursts
Authors: Thejappa, G.; MacDowall, R. J.; Gopalswamy, N.
2011ApJ...734...16T    Altcode:
  Solar type III and type II radio bursts suffer severe bending and
  group delay due to refraction while escaping from the source where
  the refractive index μ can be as low as ~0 to the observer where μ ~
  1. These propagation effects can manifest themselves as errors in the
  observed directions and times of arrival at the telescope. We describe
  a ray-tracing technique that can be used to estimate these errors. By
  applying this technique to the spherically symmetric density model
  derived using the data from the WIND/Waves experiment, we show that (1)
  the fundamental and harmonic emissions escape the solar atmosphere in
  narrow cones (at 625 kHz the widths of these escape cones are ~1fdg1
  and ~8°, respectively), (2) the errors in the angles as well as the
  times of arrival increase monotonically with the angle of arrival
  (at 625 kHz these errors are 0fdg26 and ~17.2 s for the fundamental
  and ~0fdg52 and ~7.6 s for the harmonic at the maximum possible angles
  of arrival of ~0fdg55 and ~4°, respectively), and (3) the lower the
  frequencies are, the higher the errors in both the angles and times of
  arrival are. This implies that at 625 kHz the measured arrival angles
  and arrival times of the fundamental and harmonic are off by ~50%
  and ~13%, and ~3.4% and ~1.5%, respectively.

---------------------------------------------------------
Title: Relationship between the Expansion Speed and Radial Speed of
    CMEs Confirmed Using Quadrature Observations from Soho and Stereo
Authors: Gopalswamy, N.; Makela, P.; Yashiro, S.
2011simi.conf....2G    Altcode:
  The STEREO spacecraft were in qudrature with SOHO (STEREO-A ahead of
  Earth by 87o and STEREO-B 94o behind Earth) on 2011 February 15, when
  a fast Earth-directed CME occurred. The CME was observed as a halo by
  the Large-Angle and Spectrometric Coronagraph (LASCO) on board SOHO. The
  sky-plane speed was measured by SOHO/LASCO as the expansion speed, while
  the radial speed was measured by STEREO-A and STEREO-B. In addition,
  STEREO-A and STEREO-B images measured the width of the CME, which
  is unknown from Earth view. From the SOHO and STEREO measurements,
  we confirm the relationship between the expansion speed (Vexp) and
  radial speed (Vrad) derived previously from geometrical considerations
  (Gopalswamy et al. 2009): Vrad = Ѕ (1 + cot w) Vexp, where w is the
  half width of the CME. STEREO-B images of the CME, we found that CME
  had a full width of 75 degrees, so w = 37.5 degrees. This gives the
  relation as Vrad = 1.15 Vexp. From LASCO observations, we measured
  Vexp = 897 km/s, so we get the radial speed as 1033 km/s. Direct
  measurement of radial speed from STEREO gives 945 km/s (STEREO-A) and
  1057 km/s (STEREO-B). These numbers are different only by 2.3% and 8.5%
  (for STEREO-A and STEREO-B, respectively) from the computed value.

---------------------------------------------------------
Title: A Radio Observatory on the Lunar Surface for Solar studies
    (ROLSS)
Authors: MacDowall, R. J.; Lazio, T. J.; Bale, S. D.; Burns, J.;
   Farrell, W. M.; Gopalswamy, N.; Jones, D. L.; Weiler, K. W.
2011arXiv1105.0666M    Altcode:
  By volume, more than 99% of the solar system has not been imaged at
  radio frequencies. Almost all of this space (the solar wind) can be
  traversed by fast electrons producing radio emissions at frequencies
  lower than the terrestrial ionospheric cutoff, which prevents
  observation from the ground. To date, radio astronomy-capable space
  missions consist of one or a few satellites, typically far from each
  other, which measure total power from the radio sources, but cannot
  produce images with useful angular resolution. To produce such images,
  we require arrays of antennas distributed over many wavelengths
  (hundreds of meters to kilometers) to permit aperture synthesis
  imaging. Such arrays could be free-flying arrays of microsatellites
  or antennas laid out on the lunar surface. In this white paper, we
  present the lunar option. If such an array were in place by 2020,
  it would provide context for observations during Solar Probe Plus
  perihelion passes. Studies of the lunar ionosphere's density and time
  variability are also important goals. This white paper applies to the
  Solar and Heliospheric Physics study panel.

---------------------------------------------------------
Title: What Controls the Classification of Interplanetary Mass
    Ejections
Authors: Moon, Yong-Jae; Gopalswamy, N.; Kim, R.; Xie, H.; Yashiro, S.
2011SPD....42.2401M    Altcode: 2011BAAS..43S.2401M
  In this paper we address a question what controls the classification
  of interplanetary mass ejections (ICMEs): magnetic cloud (MC) or
  ejecta (EJ). Using 186 shock-associated ICMEs from 1997 to 2006, we
  have examined three possible causes : (1) magnetic complexity with a
  proxy of sunspot number, (2) CME direction as a proxy of cone angle
  (the angle between the CME cone axis and the plane of sky), and (3)
  ICME-ICME interaction with a proxy of the number of halo CMEs. First,
  the fraction of MC is poorly anti-correlated (R=-0.36) with annual
  sunspot number. Second, the distribution of CME cone angle for 38
  EJs is not much different from that for 16 MCs. Third, the annual
  fraction of magnetic cloud is well anti-correlated (R=-0.78) with
  the annual number of halo CMEs. To demonstrate such a relationship,
  we consider all halo CMEs during the same period and statistically
  searched the candidate of interacting ICMEs according to temporal
  and spatial closeness. As a result, we find that the annual fraction
  of interacting ICME candidates is well correlated (R=0.87) with the
  annual number of the halo CMEs as well as anti-correlated (R=-0.85)
  with the annual fraction of MCs. The contingency table between ICME-ICME
  interaction and MC occurrence also shows a good statistical result:
  Hit (110), False Alarm (53), Prediction of detection 'yes' (0.88), and
  Critical Success Index (0.62). Our results imply that the interaction
  of ICMEs is mainly responsible for their classification.

---------------------------------------------------------
Title: Magnetic Field Strength in the Upper Solar Corona Using
    White-light Shock Structures Surrounding Coronal Mass Ejections
Authors: Kim, Roksoon; Gopalswamy, N.; Moon, Y.; Cho, K.; Yashiro, S.
2011SPD....42.2306K    Altcode: 2011BAAS..43S.2306K
  To measure the magnetic field strength in the solar corona, we examined
  12 fast (&gt; 1000 km s-1) limb CMEs which show clear shock-like
  structures in SOHO/LASCO observations. By applying piston-shock
  relationship to the observed CME's standoff distance and electron
  density compression ratio, we estimated the Mach number, Alfven speed,
  and magnetic field strength in the height range 3 to 15Rs. Main
  results from this study are: (1) the standoff distance observed in
  the solar corona is consistent with those from a magnetohydrodynamic
  (MHD) model and near-Earth observations; (2) the Mach number as a shock
  strength is in the range 1.49 to 3.52 from the standoff distance data,
  but when we use the compression ratio, the Mach number is in the
  range 1.47 to 1.90, implying that the measured density compression
  ratio is likely to be underestimated due to projection effects; (3)
  the Alfven speeds range from 259 to 982 km s-1 and the magnetic field
  strength is in the range 0.04 to 0.35 G when the standoff distance
  is used; (4) if we multiply the compression ratio by a factor of 2,
  the Alfven speeds and the magnetic field strengths are consistent in
  both methods; (5) the derived magnetic field strengths in the inner
  corona are similar to those of empirical models but noticeably higher
  in the upper corona. This is a new attempt to measure magnetic field
  strength from coronagraph observation alone. These observations are
  consistent with the idea that the diffuse structures surrounding the
  CME front can be interpreted as shock structures.

---------------------------------------------------------
Title: Understanding Interplanetary Shock Dynamics In The Inner
Heliosphere:The 2010 April 03 and August 01 Events
Authors: Xie, Hong; May, L.; St Cyr, C. O.; Gopalswamy, N.; Odstrcil,
   D.; Cremades, H.
2011SPD....42.2312X    Altcode: 2011BAAS..43S.2312X
  The 2010 April 03 and 2010 August 01 CMEs were studied using
  observations from STEREO A and B, and SOHO LASCO, combined with
  ENLIL+Cone model simulations preformed at the Community Coordinated
  Modelling Center (CCMC). In particular, we identified the origin of CMEs
  using STEREO EUVI and/or SDO images. A flux-rope model fitting to the
  SECCHI A and B, SOHO/LASCO images was used to determine CME directions
  and actual speeds. J-maps from COR2/HI-1/HI-2 and simulations from CCMC
  were used to study the formation and evolution of the shocks in the
  inner heliosphere. We compared the simulation results with the observed
  height-time profiles of the shock from white light and kilometric
  type II (KmTII) burst (Wind/WAVES) observations. The predicted shock
  arrival at Earth is compared with in-situ observations from ACE. It
  is found that that ENLIL+cone model predicts the kinematics of shock
  evolution well for both cases and the KmTII method is more successful
  when using ENLIL model plasma density.

---------------------------------------------------------
Title: The 2011 February 15 Coronal Mass Ejection: Reconciling SOHO
    and STEREO Observations in Quadrature
Authors: Gopalswamy, N.; Yashiro, S.; Makela, P.; Kaiser, M. L.
2011SPD....42.2322G    Altcode: 2011BAAS..43S.2322G
  The Large-Angle and Spectrometric Coronagraph (LASCO) on board SOHO
  observed a fast halo coronal mass ejection on 2011 February 15. The
  STEREO spacecraft were in qudrature with SOHO (STEREO-A ahead of Earth
  by 87 deg and STEREO-B 94 deg behind Earth), enabling CME measurement
  using the three spacecraft. The sky-plane speed measured by SOHO/LASCO
  is closely related to the expansion speed of the CME, while the
  radial speed was measured by STEREO-A and STEREO-B. In addition,
  STEREO-A and STEREO-B images measured the width of the CME, which
  is unknown from Earth view. From the SOHO and STEREO measurements,
  we confirm the relationship between the expansion speed (Vexp) and
  radial speed (Vrad) derived previously from geometrical considerations
  (Gopalswamy et al. 2009): = Vrad = ½ (1 + cot w) Vexp, where w is the
  half width of the CME. We can also measure the Earthward speed of the
  CME directly from the STEREO measurements. The travel time to Earth
  predicted from the Earthward speed using the Empirical Shock Arrival
  model is 12 hours shorter than the actual travel time obtained from in
  situ measurements at L1. The primary reason for this discrepancy seems
  to be the interaction with the two preceding CMEs that slowed down
  the CME in question. The CME interaction is also confirmed from the
  radio enhancement observed by Wind/WAVES and STEREO WAVES experiments.

---------------------------------------------------------
Title: Earth-Affecting Solar Causes Observatory (EASCO): Results of
    the Mission Concept Study
Authors: Gopalswamy, N.; EASCO Team
2011SPD....42.1518G    Altcode: 2011BAAS..43S.1518G
  Coronal mass ejections (CMEs) corotating interaction regions (CIRs)
  are two large-scale structures that originate from the Sun and affect
  the heliosphere in general and Earth in particular. While CIRs are
  generally detected by in-situ plasma signatures, CMEs are remote-sensed
  when they are still close to the Sun. The current understanding of
  CMEs primarily come from the SOHO and STEREO missions. In spite of
  the enormous progress made, there are some serious deficiencies in
  these missions. For example, these missions did not carry all the
  necessary instruments (STEREO did not have a magnetograph; SOHO did
  not have in-situ magnetometer). From the Sun-Earth line, SOHO was not
  well-suited for observing Earth-directed CMEs because of the occulting
  disk. STEREO's angle with the Sun-Earth line is changing constantly,
  so only a limited number of Earth-directed CMEs were observed in
  profile. In order to overcome these difficulties, we proposed a news L5
  mission concept known as the Earth-Affecting Solar Causes Observatory
  (EASCO). The mission concept was recently studied at the Mission
  Design Laboratory (MDL), NASA Goddard Space Flight Center. The aim of
  the MDL study was to see how the scientific payload consisting of ten
  instruments can be accommodated in the spacecraft bus, what propulsion
  system can transfer the payload to the Sun-Earth L5, and what launch
  vehicles are appropriate. The study found that all the ten instruments
  can be readily accommodated and can be launched using an intermediate
  size vehicle such as Taurus II with enhanced faring. The study also
  found that a hybrid propulsion system consisting of an ion thruster
  (using 55 kg of Xenon) and hydrazine ( 10 kg) is adequate to place the
  payload at L5. The transfer will take about 2 years and the science
  mission will last for 4 years around the next solar maximum in 2025.

---------------------------------------------------------
Title: Comparison between Linear and Quadratic Drag Models for
    ICME Propagation
Authors: Moon, Yong-Jae; Vrsnak, B.; Gopalswamy, N.; Yashiro, S.
2011SPD....42.2318M    Altcode: 2011BAAS..43S.2318M
  In this paper, we have examined a recent issue what kinds of drag
  form (linear or quadratic drag) is proper for interplanetary coronal
  mass ejections (ICMEs). For this work, we have examined well-observed
  LASCO CMEs associated with DH Type II bursts satisfying the following
  conditions: (1) the CMEs speeds are larger than 600 km/s, (2) their
  longitudes are larger than 60 degrees, (3) the numbers of their LASCO
  data points are larger than 6, and (4) their accelerations are smaller
  than -1 m/s<SUP>2</SUP>. We find that their accelerations (Log a) in
  the LASCO field of view has a very good quadratic relationship with
  the CME relative speeds Log (Vcme-400) with the correlation coefficient
  of R=0.83, supporting the quadratic drag force. Another test has been
  made by applying two drag models to two well-observed STEREO/SECCHI
  events. As a result, we found that (1) while two speed profiles are
  well fitted by the quadratic drag model, one speed profile can not be
  fitted by the linear model; (2) while the physical parameters for the
  quadratic model are well consistent with observations, the kinematic
  viscosity for the linear model should be four orders larger than its
  observed value. From this study, we conclude that the quadratic drag
  model for ICME propagation should be proper than the linear drag model.

---------------------------------------------------------
Title: Halo Coronal Mass Ejections: Comparing Observations to Models
Authors: Gilbert, Holly; Orlove, M.; St. Cyr, O.; Xie, H.; Mays,
   L. M.; Gopalswamy, N.
2011SPD....42.2310G    Altcode: 2011BAAS..43S.2310G
  Since 1996, the SOHO LASCO coronagraphs have detected "halo” CMEs
  that appear to be directed toward Earth, but information about the
  size and speed of these events seen face-on has been limited. From a
  single vantage point along the Sun-Earth line, the primary limitation
  has been ambiguity in fitting the cone model (or other forward-modeling
  techniques, e.g., Thernisian et al., 2006). But in the past few years,
  the STEREO mission has provided a view of Earth-directed events from
  the side. These events offer the opportunity to compare measurements
  (width and speed) of halo CMEs observed by STEREO with models that
  derive halo CME properties. We report here results of such a comparison
  on a large sample of LASCO CMEs in the STEREO era.

---------------------------------------------------------
Title: Association of EUV Waves and Coronal Mass Ejections
Authors: Yashiro, Seiji; Gopalswamy, N.
2011SPD....42.2317Y    Altcode: 2011BAAS..43S.2317Y
  The association between EUV waves and coronal mass ejections (CMEs)
  is difficult to establish for disk flares using observations from the
  Sun-Earth line because of visibility issues. The other possibility is
  the real absence of mass motion in flares. This issue can be effectively
  addressed by the twin spacecraft of the Solar Terrestrial Relations
  Observatory (STEREO) mission. The Ahead and Behind spacecraft of the
  STEREO mission were located around ±90° from the Sun-Earth line
  from 2010 to 2012. This is the first opportunity to investigate
  the connection between CMEs and EUV waves with a high degree of
  accuracy. During January 28 - March 9, 2011, two X- and 28 M-class
  flares occurred. We examined their CME associations using STEREO/SECCHI
  and SOHO/LASCO observations, and EUV wave associations using SDO/AIA
  data. We found that 10 out of 30 flares were associated with clear
  flux-rope CMEs (FRCMEs) while 16 did not have any erupting features
  above the flaring regions in the coronagraph images. The remaining
  four flares had narrow CMEs or outflow above the flaring regions but
  their connection to the flares is unclear. We also found all of the
  FRCME-associated flares had clear EUV waves, while the flares without
  CMEs also lacked EUV waves. We found one-to-one correspondence between
  EUV waves and FRCMEs.

---------------------------------------------------------
Title: Source of Coronal and IP Type II Bursts Inferred from Radio
    and White-light Observations
Authors: Makela, Pertti; Gopalswamy, N.; Yashiro, S.
2011SPD....42.2316M    Altcode: 2011BAAS..43S.2316M
  We report on a study of the speeds of type II radio bursts in the metric
  (m) and dekameter-hectometric (DH) wavelength range constrained by
  the time-height measurements of the associated coronal mass ejections
  (CMEs). Dynamic spectra of type II bursts show occasionally a clear
  discontinuity in frequency and temporal overlap of metric and DH
  type II bursts. This has been interpreted to signify either (1) a
  different origin of the type II components, i.e., the DH-component is
  caused by a CME-driven shock and the m-component by a blast wave or
  unknown source, or (2) same source but a different location, i.e.,
  the DH-component originates from the shock nose and the m-component
  from the shock flanks. Our preliminary results suggest that the single
  CME-driven shock scenario can match both m and DH-component of type
  II bursts reasonably well, assuming that true space speeds of the CMEs
  and shocks are utilized.

---------------------------------------------------------
Title: Cme Evolution In The Interplanetary Space Based On Stereo
    Observations.
Authors: Poomvises, Watanachak; Gopalswamy, N.; Zhang, J.
2011SPD....42.2311P    Altcode: 2011BAAS..43S.2311P
  STEREO/SECCHI observations help identify the true 3-D geometric
  structure of CMEs and track their true evolution in the inner
  heliosphere. Using STEREO observations, it is possible to obtain the
  true speed of CMEs, which is key in predicting the arrival time of CMEs
  at Earth (Gopalswamy et al. 2001). From the STEREO data, we are able to
  track and measure CMEs in 3-D by using Raytrace model (Thernisien et
  al 2006, 2009), which is free from projection effects and thus result
  in true CME velocities. Studied study 5 CME events, we found that the
  acceleration/deceleration of CMEs occur within 50 Rs from the Sun,
  after that the CME velocity converges to the narrow range (Poomvises
  et al 2010). Additionally, we found that expansion velocity of CMEs
  also converges to a narrow range after 50 Rs. <P />The observations are
  consistent with the theoretical flux rope model. The CME evolution can
  be explained by different forces that act on the CME: Lorentz force,
  thermal pressure force, gravity force, aero-dynamic drag force, and the
  magnetic drag force. The drag coefficient typically varies between 2.5
  to 3.0, which is much smaller than the factor of twelve suggested by
  earlier studies. Moreover, the value of the polytropic index has been
  found to be between 1.35 to 1.60. Therefore, we have been able to narrow
  down the range of values for the drag coefficient and the polytropic
  index, which help in improve the prediction of CME travel time.

---------------------------------------------------------
Title: Earth-Affecting Solar Causes Observatory (EASCO): A potential
    International Living with a Star Mission from Sun-Earth L5
Authors: Gopalswamy, N.; Davila, J. M.; St. Cyr, O. C.; Sittler,
   E. C.; Auchère, F.; Duvall, T. L.; Hoeksema, J. T.; Maksimovic, M.;
   MacDowall, R. J.; Szabo, A.; Collier, M. R.
2011JASTP..73..658G    Altcode:
  This paper describes the scientific rationale for an L5 mission
  and a partial list of key scientific instruments the mission should
  carry. The L5 vantage point provides an unprecedented view of the
  solar disturbances and their solar sources that can greatly advance
  the science behind space weather. A coronagraph and a heliospheric
  imager at L5 will be able to view CMEs broadsided, so space speed
  of the Earth-directed CMEs can be measured accurately and their
  radial structure discerned. In addition, an inner coronal imager
  and a magnetograph from L5 can give advance information on active
  regions and coronal holes that will soon rotate on to the solar
  disk. Radio remote sensing at low frequencies can provide information
  on shock-driving CMEs, the most dangerous of all CMEs. Coordinated
  helioseismic measurements from the Sun-Earth line and L5 provide
  information on the physical conditions at the base of the convection
  zone, where solar magnetism originates. Finally, in situ measurements
  at L5 can provide information on the large-scale solar wind structures
  (corotating interaction regions (CIRs)) heading towards Earth that
  potentially result in adverse space weather.

---------------------------------------------------------
Title: Coronal mass ejections and their heliospheric consequences
Authors: Gopalswamy, N.
2011ASInC...2..241G    Altcode:
  This paper is concerned with the properties of coronal mass ejections
  (CMEs) that affect the heliosphere. The special populations of CMEs
  that drive shocks, accelerate solar energetic particles, and produce
  geomagnetic storms are discussed in comparison with the general
  population (all CMEs of cycle 23). It is shown that the average CME
  speeds of the special populations are larger than that of the general
  population by a factor in the range 2--3. The angular width of these
  CMEs is also generally large because most of the CMEs were halos. The
  October -- November 2003 period produced a large number of energetic
  CMEs, two of which were of historical proportions. These extreme events
  are discussed in order to understand what one might expect from the
  Sun as the largest event, given the maximum area and magnetic field
  strength of the source active regions.

---------------------------------------------------------
Title: Universal Heliophysical Processes
Authors: Gopalswamy, Nat
2011sswh.book....9G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Coronal Mass Ejections and Solar Radio Emissions
Authors: Gopalswamy, N.
2011pre7.conf..325G    Altcode:
  Three types of low-frequency nonthermal radio bursts are associated
  with coronal mass ejections (CMEs): Type III bursts due to accelerated
  electrons propagating along open magnetic field lines, type II bursts
  due to electrons accelerated in shocks, and type IV bursts due to
  electrons trapped in post-eruption arcades behind CMEs. This paper
  presents a summary of results obtained during solar cycle 23 primarily
  using the white-light coronagraphic observations from the Solar
  Heliospheric Observatory (SOHO) and the WAVES experiment on board Wind.

---------------------------------------------------------
Title: Observing Solar Radio Bursts from the Lunar Surface
Authors: MacDowall, R. J.; Lazio, T. J.; Bale, S. D.; Burns, J.;
   Gopalswamy, N.; Jones, D. L.; Kaiser, M. L.; Kasper, J. C.; Weiler,
   K. W.
2011pre7.conf..541M    Altcode:
  Locating low frequency radio observatories on the lunar surface has a
  number of advantages, including fixed locations for the antennas and no
  terrestrial inteference on the far side of the moon. Here, we describe
  the Radio Observatory on the Lunar Surface for Solar studies (ROLSS),
  a concept for a near-side, low frequency, interferometric radio imaging
  array designed to study particle acceleration in the corona and inner
  heliosphere. ROLSS would be deployed during an early lunar sortie or
  by a robotic rover as part of an unmanned landing. The prime science
  mission is to image intense type II and type III solar radio bursts
  with the aim of determining the sites at and mechanisms by which the
  radiating particles are accelerated. Secondary science goals include
  constraining the density of the lunar ionosphere by searching for a low
  radio frequency cutoff of the solar radio emissions and detecting the
  low energy electron population in astrophysical sources. Furthermore,
  ROLSS serves as a pathfinder for larger, far-side lunar radio arrays,
  designed for faint sources.

---------------------------------------------------------
Title: The International Space Weather Initiative (ISWI)
Authors: Davila, Joseph M.; Gopalswamy, Nat; Thompson, Barbara J.;
   Bogdan, Tom; Hapgood, Mike
2011sswh.book..375D    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Heliocentric Distance of Coronal Mass Ejections at the Time of
Energetic Particle Release: Revisiting the Ground Level experiments
    and instrumentation
Authors: Gopalswamy, Nat
2011ICRC...10..159G    Altcode: 2011ICRC...32j.159G
  No abstract at ADS

---------------------------------------------------------
Title: Low-frequency type III radio bursts and solar energetic
    particle events
Authors: Gopalswamy, N.; Mäkelä, P.
2011CEAB...35...71G    Altcode:
  Complex type III bursts at low-frequencies (&lt;14 MHz) are thought
  to indicate large solar energetic particle (SEP) events. We analysed
  six complex type III bursts from the same active region, one of which
  was not accompanied by a SEP event. This event was accompanied by a
  fast and wide coronal mass ejection (CME), but lacked a type II burst
  and an interplanetary shock. When we examined the evolution and the
  magnetic configuration of the active region, we did not find anything
  peculiar. The lowest frequency of type III emission occurred at the
  local plasma frequency in the vicinity of the Wind spacecraft that
  observed the type III, which confirms that the magnetic connectivity of
  the source region was good. We conclude that the lack of SEPs is due to
  the lack of production rather than due to poor magnetic connectivity. We
  also show that neither the type III burst duration nor the burst
  intensity was able to distinguish between SEP and non-SEP events. The
  lack of SEP event can be readily explained under the shock-acceleration
  paradigm, but not under the flare-acceleration paradigm.

---------------------------------------------------------
Title: Maximum Coronal Mass Ejection Speed as an Indicator of Solar
    and Geomagnetic Activities
Authors: Kilcik, A.; Yurchyshyn, V. B.; Abramenko, V.; Goode, P. R.;
   Gopalswamy, N.; Ozguc, A.; Rozelot, J. P.
2011ApJ...727...44K    Altcode: 2011arXiv1111.4000K
  We investigate the relationship between the monthly averaged maximal
  speeds of coronal mass ejections (CMEs), international sunspot number
  (ISSN), and the geomagnetic Dst and Ap indices covering the 1996-2008
  time interval (solar cycle 23). Our new findings are as follows. (1)
  There is a noteworthy relationship between monthly averaged maximum CME
  speeds and sunspot numbers, Ap and Dst indices. Various peculiarities
  in the monthly Dst index are correlated better with the fine structures
  in the CME speed profile than that in the ISSN data. (2) Unlike the
  sunspot numbers, the CME speed index does not exhibit a double peak
  maximum. Instead, the CME speed profile peaks during the declining
  phase of solar cycle 23. Similar to the Ap index, both CME speed and
  the Dst indices lag behind the sunspot numbers by several months. (3)
  The CME number shows a double peak similar to that seen in the sunspot
  numbers. The CME occurrence rate remained very high even near the
  minimum of the solar cycle 23, when both the sunspot number and the
  CME average maximum speed were reaching their minimum values. (4) A
  well-defined peak of the Ap index between 2002 May and 2004 August was
  co-temporal with the excess of the mid-latitude coronal holes during
  solar cycle 23. The above findings suggest that the CME speed index may
  be a useful indicator of both solar and geomagnetic activities. It may
  have advantages over the sunspot numbers, because it better reflects
  the intensity of Earth-directed solar eruptions.

---------------------------------------------------------
Title: Understanding Interplanetary Shock Dynamics in the Inner
    Heliosphere with New Observations and Modeling Techniques
Authors: St Cyr, O. C.; Henning, C.; Xie, H.; Odstrcil, D.; Mays,
   L.; Cremades, H.; Iglesias, F.; Gopalswamy, N.; Kaiser, M. L.
2010AGUFMSH23B1850S    Altcode:
  This is a status report of our work predicting interplanetary shock
  location and strength throughout the inner heliosphere. Coronal mass
  ejection (CME) shocks accelerate energetic particles, and CME sheaths
  and ejecta are the primary cause of severe geomagnetic storms. We have
  evaluated an empirical prediction technique against ENLIL model runs
  produced at the Community Coordinated Modelling Center (CCMC). The
  prediction method is a technique based on the kilometric wavelength
  interplanetary Type II radio emissions measured by Wind/WAVES
  and described by Cremades, et al., 2007 (hereafter called "kmTII"
  technique). For a subset of Earth-directed CMEs that were also observed
  by SOHO LASCO, we have produced multiple ENLIL+cone model predictions
  of the location of the shock and compared the predicted arrival of at
  Earth with both the actual arrival and the kmTII prediction. We will
  report the preliminary results of the comparison in this poster.

---------------------------------------------------------
Title: Aspects of Coronal Mass Ejections Related to Space Weather
Authors: Gopalswamy, N.
2010AGUFMSH52A..03G    Altcode:
  Solar cycle 23 witnessed an unprecedented array of space- and
  ground-based instruments observing the violent eruptions from the
  Sun that had huge impact on the heliosphere. It was possible to
  characterize coronal mass ejections (CMEs) that cause extreme solar
  energetic particle events and geomagnetic storms, the two aspects that
  concern the space weather community. In this paper I discuss the special
  populations of CMEs that have significant interplanetary consequences:
  shock-driving CMEs identified based on their association with type II
  radio bursts and in-situ shocks, SEP-producing CMEs, and geoeffective
  CMEs (those that produce geomagnetic storms). I discuss the kinematic
  and solar-source properties of these populations and how they vary
  with the solar activity cycle. I also compare their properties with
  the general population of CMEs, so one can recognize when and where
  these events occur on the Sun.

---------------------------------------------------------
Title: Relation between CME Speed and Magnetic Helicity in Solar
    Source Regions
Authors: Jung, H.; Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Xie, H.
2010AGUFMSH51C1686J    Altcode:
  Coronal mass ejections (CMEs) are thought to be powered by the free
  energy in the solar source regions. The magnetic helicity in the source
  regions is one of the indicators of this free energy. In order to see
  the relationship between the magnetic helicity of CME source regions and
  CME energy, we considered a set of 41 solar source regions (from solar
  cycle 23) from which CMEs erupted and ended up as magnetic clouds near
  Earth. Using EUV and magnetogram data from the Solar and Heliospheric
  Observatory (SOHO) mission, we determined the most probable linear
  force-free magnetic structure and its magnetic helicity for each CME
  source region. The magnetograms taken just prior to the CME eruption
  were used to compute the magnetic helicity. The CME speeds were obtained
  from the SOHO/LASCO CME catalog (http://cdaw.gsfc.nasa.gov). We found
  that the magnetic helicity is positively correlated with the speed of
  CMEs. This result suggests that the magnetic helicity of CME source
  regions maybe useful for predicting CME speed.

---------------------------------------------------------
Title: Statistical Study of Solar Activity Associated with SOHO UVCS
    Coronal Mass Ejections
Authors: O'Neill, J. F.; St Cyr, O. C.; Mays, L.; Gopalswamy, N.;
   Raymond, J. C.; Ciaravella, A.; Yashiro, S.; Xie, H.; Giordano, S.;
   Quirk, C.
2010AGUFMSH23B1838O    Altcode:
  Recently a preliminary catalogue of coronal mass ejections (CMEs)
  detected by the SOHO ultraviolet coronal spectrometer (UVCS) has been
  made available to the scientific community through the online LASCO CME
  catalogue (http://cdaw.gsfc.nasa.gov/). We have undertaken an initial
  study to identify solar activity associated with the UVCS CMEs with
  radio Type II events, and EUV and X-ray flares. Over 800 CMEs have
  been identified in UVCS data, and we have found associated activity
  for 185 events. In this poster we report the basic statistics as a
  function of time, longitude, latitude, CME speed, etc.

---------------------------------------------------------
Title: An Earth-Directed CME not Observed in LASCO Images
Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.
2010AGUFMSH23A1835Y    Altcode:
  The COR1 coronagraphs on STEREO-A and -B observed an Earth-directed
  CME originating from N09W15 at 02:20 UT on 2010/07/09. The apparent
  CME speed is only 291 km/s, and the angular width is 60 degrees. The
  CME is somewhat slower than the average LASCO CME (average speed ~450
  km/s) but not narrow. The CME was expected to be seen as a halo CME
  because of the geometry and large width. However, the CME could not
  be identified in the LASCO running difference movie because of the
  visibility of the white-light coronagraph. On the other hand, EUV
  images taken by SDO/AIA show a clear dimming to the northwest of the
  source region and a wave-like feature propagating to the east. Faint
  Earth-directed CMEs, seem to be better indicated by surface eruptive
  signatures such as dimming and EUV waves. We discuss how to estimate
  CME parameters using the EUV data alone.

---------------------------------------------------------
Title: Radio-Loud Coronal Mass Ejections without Shocks near Earth
Authors: Akiyama, S.; Gopalswamy, N.; Xie, H.; Yashiro, S.; Makela,
   P. A.; St Cyr, O. C.; MacDowall, R. J.; Kaiser, M. L.
2010AGUFMSH32A..07A    Altcode:
  Type II radio bursts are produced by low energy electrons accelerated
  in shocks driven by coronal mass ejections (CMEs). One can infer shocks
  near the Sun, in the Interplanetary medium, and near Earth depending
  on the wavelength range in which the type II bursts are produced. In
  fact, type II bursts are good indicators of CMEs that produce solar
  energetic particles. If the type II burst occurs from a source on the
  Earth-facing side of the solar disk, it is highly likely that a shock
  arrives at Earth in 2-3 days and hence can be used to predict shock
  arrival at Earth. However, a significant fraction of CMEs producing
  type II bursts were not associated shocks at Earth, even though the
  CMEs originated close to the disk center. There are several reasons
  for the lack of shock at 1 AU. CMEs originating at large central
  meridian distances (CMDs) may be driving a shock, but the shock may
  not be extended sufficiently to reach to the Sun-Earth line. Another
  possibility is CME cannibalism because of which shocks merge and one
  observes a single shock at Earth. Finally, the CME-driven shock may
  become weak and dissipate before reaching 1 AU. We examined a set
  of 30 type II bursts observed by the Wind/WAVES experiment that had
  the solar sources very close to the disk center (within a CMD of 15
  degrees), but did not have shock at Earth. We find that the near-Sun
  speeds of the associated CMEs average to ~600 km/s, only slightly
  higher than the average speed of CMEs associated with radio-quiet
  shocks. However, the fraction of halo CMEs is only ~28%, compared
  to 40% for radio-quiet shocks and 72% for all radio-loud shocks. We
  conclude that the disk-center radio loud CMEs with no shocks at 1 AU are
  generally of lower energy and they drive shocks only close to the Sun.

---------------------------------------------------------
Title: The Relation between Coronal Holes and CMEs during the Rise,
    Maximum and Declining Phases of the Solar Cycle 23
Authors: Mohamed, A. A.; Gopalswamy, N.; Yashiro, S.; Akiyama, S.;
   Makela, P. A.; Xie, H.; Jung, H.
2010AGUFMSH23B1852M    Altcode:
  We investigate the influence of coronal holes (CHs) on the propagation
  of CMEs considering both magnetic clouds (MCs) and non-magnetic clouds
  (non-MCs), during the three phases of the solar cycle 23. We consider
  events originating within a central meridian distance of 15○. The
  influence of the CHs is computed as a fictitious force that depends
  on the CH area, the distance between the CH and the eruption region,
  and the magnetic field within the CH at the photospheric level. We find
  that the influence parameter is the smallest during the rise phase of
  the cycle and increases during the maximum and then in the declining
  phases. The largest influence parameter was observed to be for non-MCs
  in the Maximum phase F= 2.9 G. However, the average influence parameter
  is only about half of what was computed for driverless shocks F= 5.8
  G. The CH effect on the non-MCs is found to be larger than that for MCs
  during maximum phase; this may suggest that non-MCs may also have flux
  rope structure which is hidden from observation due to the deflection by
  the nearby CHs as has been suggested in the case of driverless shocks
  (Gopalswamy et al., 2009, JGR). reference: Gopalswamy, N., p. Makela,
  H. Xie, S. Akiyama, and S. Yashiro, (2009), "CME Interaction with
  coronal holes and their interplanetary consequences" , J. Geophys. Res.,
  114,A00A22 doi:10.1029/2008JA013686.

---------------------------------------------------------
Title: On the Occurrence of Energetic Storm Particle Events and Type
    II Radio Bursts in CME-driven Shocks
Authors: Makela, P. A.; Gopalswamy, N.; Akiyama, S.; Xie, H.;
   Yashiro, S.
2010AGUFMSH23B1847M    Altcode:
  We discuss correlations between energetic storm particle (ESP) events
  and type II radio emission associated with coronal mass ejection-driven
  shocks detected during 1996-2006. Shocks that could not be associated
  with any type II radio emission within metric-to-kilometric wavelength
  range were defined to be radio-quiet (RQ). All other shocks were defined
  to be radio-loud (RL). ESP events were identified from the 66 keV-50
  MeV proton intensities measured by the Electron, Proton and Alpha
  Monitor (EPAM) instrument on the Advanced Composition Explorer (ACE)
  spacecraft and the Energetic and Relativistic Nuclei and Electron (ERNE)
  experiment on the Solar and Heliospheric Observatory (SOHO). Electron
  ESP events were identified in the 38-53 keV energy channel of EPAM. It
  is remarkable that a large fraction (32%) of RQ shocks produced a
  particle flux increase at energies above 1.8 MeV. On the other hand,
  only 52% of RL shocks produced ESP events. Electron ESP events were
  observed in 20% of RQ shocks and 39% of RL shocks. We also find that
  ESP events during RQ shocks are less intense than those associated
  with RL shocks. Among RQ shocks, those with an ESP event have slightly
  more eastern source longitudes (median longitude E07), whereas those
  without have more western longitudes (median longitude W03). This
  difference probably reflects the asymmetry in the relative size of ESP
  events between the eastern and western flanks of the shock. Our results
  indicate that type II emission is important for the occurrence of ESP
  events. RL shocks produce frequently ESP events, and the associated ESP
  events are also more intense than those observed during RQ shocks. The
  variability in the occurrence of ESP events and type II radio bursts is
  probably due to differences in the shock formation in the low corona
  and changes in the properties of the shocks as they propagate through
  interplanetary space, and the escape efficiency of accelerated particles
  from the shock front.

---------------------------------------------------------
Title: International Space Weather Initiative (ISWI)
Authors: Gopalswamy, N.; Davila, J. M.
2010nspm.conf..160G    Altcode:
  The International Space Weather Initiative (ISWI) is an international
  scientific program to understand the external drivers of space
  weather. The science and applications of space weather has been
  brought to prominence because of the rapid development of space based
  technology that is useful for all human beings. The ISWI program has
  its roots in the successful International Heliophysical Year (IHY)
  program that ran during 2007 - 2009. The primary objective of the ISWI
  program is to advance the science space weather by a combination of
  instrument deployment, analysis and interpretation of space weather
  data from the instruments deployed in conjunction with space data,
  and communicate the results to the public and students. Like the IHY,
  the ISWI will be a grass roots organization with key participation
  from national coordinators with cooperation in an international
  steering committee. This talk outlines the ISWI program including its
  organization and proposed activities.

---------------------------------------------------------
Title: Opportunities for Ionospheric Science as Part of the
    International Space Weather Initiative (ISWI) (Invited)
Authors: Davila, J. M.; Gopalswamy, N.; Haubold, H.
2010AGUFMSA43C..01D    Altcode:
  The International Heliophysical Year (IHY), which lasted for
  approximately two years and involved the effort of thousands of
  scientists from over 70 countries, ended in February 2009. The
  major objectives of the IHY included over 60 collaborative studies
  of universal physical processes in the solar system, the deployment
  of arrays of small instruments to observe heliophysical processes, a
  unique program of educational and public outreach, and the preservation
  of the history of the IGY. The International Space Weather Initiative
  (ISWI), an international effort fully supported by the United Nations,
  is designed to build on the momentum developed during the IHY to
  develop the capability to observe, understand, and predict space
  weather phenomena, and provide the opportunity for the deployment
  of new instrumentation in Africa and other regions. In this talk the
  basic elements of the ISWI will be discussed, and the opportunities
  for the deployment of new instrument will be discussed.

---------------------------------------------------------
Title: Understanding Interplanetary Shock Dynamics in the Inner
Heliosphere with New Observations and Modeling Techniques: Case
    studies on the 2010-04-03 and 2010-08-01 events
Authors: Xie, H.; Mays, L.; St Cyr, O. C.; Gopalswamy, N.; Odstrcil,
   D.; Cremades, H.
2010AGUFMSH23B1858X    Altcode:
  The 2010 April 03 and August 01 CMEs were studied using observations
  from STEREO A and B, and SOHO LASCO, combined with ENLIL+Cone model
  simulations preformed at the Community Coordinated Modelling Center
  (CCMC). In particular, we identified the origin of CMEs using STEREO
  EUVI and/or SDO images. A flux-rope model fitting to the SECCHI A
  and B, SOHO/LASCO images was used to reconstruct the 3D structures
  of CMEs and determine their actual speeds. J-maps were obtained from
  COR-2/HI-1/HI-2 and simulations using ENLIL+cone model were conducted
  to study the formation and evolution of the CME-driven shocks in the
  inner heliosphere. We compared the simulation results with the observed
  height-time profiles of the shocks from white light and kilometric
  type II burst (Wind/WAVES) observations. The predicted shock arrival
  at Earth is compared with in-situ observations from ACE and Wind. We
  report the preliminary results of the study in this poster.

---------------------------------------------------------
Title: Corona Mass Ejections: a Summary of Recent Results
Authors: Gopalswamy, N.
2010nspm.conf..108G    Altcode:
  Corona mass ejections (CMEs) have been Recognized as the most energetic
  phenomenon in the heliosphere, deriving their energy from the stressed
  magnetic fields on the Sun. This paper highlights some of the recent
  results obtained on CMEs from the Solar and Heliospheric Observatory
  (SOHO) and the Solar Terrestrial Relations Observatory (STEREO)
  missions. The summary of follows the talk. SOHO observations revealed
  that the CME rate is almost a factor of: Two larger than previously
  thought and varied with the solar activity cycle in a complex way
  (eg, high-latitude CMEs occurred in great abundance during the solar
  years maximum). CMEs were found to interact with other CMEs as well
  as with other large-scale structures (corona holes), Resulting in
  deflections and additional particle acceleration. STEREO observations
  have confirmed the three-dimensional nature of CMEs and shocks the
  surrounding them. The EUV signatures (flare arcades, Corona dimming,
  filament Eruption, and EUV waves) associated with CMEs have become vital
  in the identification of sources from Which solar CMEs erupt. CMEs
  with speeds exceeding the characteristic speeds of the corona and
  the interplanetary medium drive shocks, which produce type II radio
  bursts. The wavelength range of type II bursts depends on the CME
  kinetic energy: type II bursts with emission components at all
  wavelengths (metric to kilometric) due to CMEs are of the highest
  kinetic energy. Some CMEs, as fast as 1600 km / s do not produce
  type II bursts, while slow CMEs (400 km / s) occasionally produce
  type II bursts. These observations can be explained as the variation
  in the ambient flow speed (solar wind) speed and the Alfvén. Not
  all CME-driven shocks produce type II bursts because they are either
  subcritical Or do not have the appropriate geometry. The same shocks
  that produce type II bursts also produce solar energetic particles
  (SEPS), Whose release near the Sun seems to be delayed with respect to
  the onset of type II bursts. This may indicate a subtle difference in
  the acceleration of the ions and ~ 10 keV electrons needed to produce
  type II bursts. Surprisingly, some shocks lacking type II bursts are
  associated with energetic storm particle events (ESPs), pointing to the
  importance of electron escape from the shock for producing the radio
  emission. CMEs slow down or accelerate in the interplanetary medium
  because of the drag force, which modifies the transit time of CMEs
  and shocks. Halo CMEs that appear to surround the occulting disk were
  known before the SOHO era, and occasional events. During the SOHO era,
  they became very prominent because of their ability to impact Earth and
  producing geomagnetic storms. Halo CMEs are generally more energetic
  than ordinary CMEs, which means they can produce north of the impact
  on Earth's magnetosphere. Their origin close to the center disk of the
  Sun ensures direct impact on the magnetosphere, although their internal
  magnetic structure is crucial in causing storms. The solar sources of
  CMEs that produce SEP events at Earth, on the other hand, are generally
  in the western hemisphere because of the magnetic connectivity. Thus,
  CMEs are very interesting from the point of view of plasma physics as
  well as practical implications because of their space weather impact.

---------------------------------------------------------
Title: A Catalog of Halo Coronal Mass Ejections from SOHO
Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Xie, H.; Mäkelä,
   P.; Vourlidas, A.; Howard, R. A.
2010SunGe...5....7G    Altcode:
  Coronal mass ejections (CMEs) that appear to surround the occulting
  disk of the observing coronagraph are known as halo CMEs. Halos
  constitute a subset of energetic CMEs that have important heliospheric
  consequences. Here we describe an on-line catalog that contains all
  the halo CMEs that were identified in the images obtained by the
  Solar and Heliospheric Observatory (SOHO) mission's Large Angle and
  Spectrometric Coronagraph (LASCO) since 1996. Until the end of 2007,
  some 396 halo CMEs were recorded. For each halo CME, we identify
  the solar source (heliographic coordinates), the soft X-ray flare
  importance, and the flare onset time. From the sky-plane speed
  measurements and the solar source information we obtain the space
  speed of CMEs using a cone model. In addition to the description of
  the catalog (http://cdaw.gsfc.nasa.gov/CME_list/HALO/halo.html), we
  summarize the statistical properties of the halo CMEs. We confirm that
  halo CMEs are twice faster than ordinary CMEs and are associated with
  major flares on the average. We also compared the annual rate of halo
  CMEs with that obtained by automatic detection methods and found that
  most of these methods have difficulty in identifying full halo CMEs.

---------------------------------------------------------
Title: Long-duration Low-frequency Type III Bursts and Solar Energetic
    Particle Events
Authors: Gopalswamy, Nat; Mäkelä, Pertti
2010ApJ...721L..62G    Altcode:
  We analyzed the coronal mass ejections (CMEs), flares, and type II
  radio bursts associated with a set of three complex, long-duration,
  low-frequency (&lt;14 MHz) type III bursts from active region 10588
  in 2004 April. The durations were measured at 1 and 14 MHz using data
  from Wind/WAVES and were well above the threshold value (&gt;15 minutes)
  normally used to define these bursts. One of the three type III bursts
  was not associated with a type II burst, which also lacked a solar
  energetic particle (SEP) event at energies &gt;25 MeV. The 1 MHz
  duration of the type III burst (28 minutes) for this event was near
  the median value of type III durations found for gradual SEP events
  and ground level enhancement events. Yet, there was no sign of an SEP
  event. On the other hand, the other two type III bursts from the same
  active region had similar duration but were accompanied by WAVES type
  II bursts; these bursts were also accompanied by SEP events detected
  by SOHO/ERNE. The CMEs for the three events had similar speeds, and
  the flares also had similar size and duration. This study suggests
  that the occurrence of a complex, long-duration, low-frequency type
  III burst is not a good indicator of an SEP event.

---------------------------------------------------------
Title: Type III Radio Burst Duration and SEP events
Authors: Gopalswamy, Nat; Makela, P.; Xie, H.
2010shin.confE..19G    Altcode:
  Long-duration (&gt;15 min), low-frequency (&lt;14 MHz) type III radio
  bursts have been reported to be indicative of solar energetic particle
  (SEP) events. We measured the durations of type III bursts associated
  with large SEP events of solar cycle 23. The Type III durations are
  distributed symmetrically at 1 MHz yielding a mean value of 34 min
  (median = 33 min) for the large SEP events. When the SEP events with
  ground level enhancement (GLE) are considered, the distribution is
  essentially unchanged (mean = 32 min; median = 30 min). To test the
  importance of type III bursts in indicating SEP events, we considered a
  set of six type III bursts from the same active region (AR 10588) whose
  durations fit the 'long duration' criterion. We analyzed the coronal
  mass ejections (CMEs), flares, and type II radio bursts associated
  with the type III bursts. The CMEs were of similar speeds and the
  flares are also of similar size and duration. All but one of the type
  III bursts was not associated with a type II burst in the metric or
  longer wavelength domains. The burst without type II burst also lacked
  a SEP event at energies &gt;25 MeV. The 1-MHz duration of the type III
  burst (28 min) is near the median value of type III durations found
  for gradual SEP events and ground level enhancement (GLE) events. Yet,
  there was no sign of SEP events. On the other hand, two other type III
  bursts from the same active region had similar duration but accompanied
  by WAVES type II bursts; these bursts were also accompanied by SEP
  events detected by SOHO/ERNE. This study suggests that the type III
  burst duration may not be a good indicator of an SEP event, consistent
  with the statistical study of Cliver and Ling (2009, ApJ).

---------------------------------------------------------
Title: Shock-driving CMEs near the Sun, in the Interplanetary Medium,
    and near Earth.
Authors: Gopalswamy, Nat; Xie, H.; Makela, P.; Akiyama, S.; Yashiro,
   S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. -L.
2010shin.confE.133G    Altcode:
  The excellent correspondence between type II radio bursts and
  solar energetic particles (SEPs) made it clear that the same shock
  accelerates ions and electrons. A recent investigation involving a
  large number of IP shocks revealed that about 35% of IP shocks do not
  produce type II bursts (radio quiet) or SEPs. Comparing the RQ shocks
  with the radio loud (RL) ones revealed some interesting results,
  which will be summarized in this poster. (1) There is no evidence
  for blast waves. (2) Even a small fraction (20%) of RQ shocks is
  associated with ion enhancements at the shock when the shock passes
  the spacecraft. (3) The primary difference between the RQ and RL
  shocks can be traced to the different kinematic properties of the
  associated CMEs, although the shock properties measured at 1 AU are
  not too different for the RQ and RL cases. This can be attributed
  to the interaction with the IP medium, which seems to erase the
  difference. More details can be found in Astrophysical Journal 710,
  1111, 2010 (http://adsabs.harvard.edu/abs/2009arXiv0912.4719G).

---------------------------------------------------------
Title: The Relation Between Coronal Holes and CMEs During the Rise,
    Maximum and Declining Phases of the Solar Cycle 23
Authors: Mohamed, Amaal Abd-Alla; Gopalswamy, N.; Yashiro, S.; Akiyama,
   S.; Makela, P.; Xie, H.; Jung, H.
2010shin.confE.141M    Altcode:
  We investigate the influence of coronal holes on the propagation of
  CMEs considering both magnetic clouds (MCs) and non-magnetic clouds
  (non-MCs), during the three phases of the solar cycle 23. We consider
  events originating within a central meridian distance of 15o. The
  influence of the CHs is computed as a fictitious force that depends
  on the CH area, the distance between the CH and the eruption region,
  and the magnetic field within the CH at the photospheric level. We find
  that the influence parameter is the smallest during the rise phase of
  the cycle and increases during the maximum and then in the declining
  phases. The largest influence parameter was observed in the declining
  phase. However, the average influence parameter is only about half of
  what was computed for driverless shocks (Gopalswamy et al., 2009, JGR).

---------------------------------------------------------
Title: Relation between Magnetic Helicity and CME Speed in Solar
    Source Regions
Authors: Jung, Hyewon; Gopalswamy, Nat; Akiyama, Sachiko; Yashiro,
   Seiji; Xie, Hong
2010shin.confE..88J    Altcode:
  Coronal mass ejections (CMEs) are thought to be powered by the free
  energy in the solar source regions. The magnetic helicity in the source
  regions is one of the indicators of this free energy. In order to
  see the relationship between the magnetic helicity and CME energy, we
  considered a set of 41 solar source regions (from solar cycle 23) from
  which CMEs erupted and ended up as magnetic clouds near Earth. Using
  EUV and magnetogram data from the Solar and Heliospheric Observatory
  (SOHO) mission, we determined the most probable linear force free
  magnetic structure and its magnetic helicity for each CME source
  region. The magnetograms taken just prior to the CME eruption were
  used to compute the magnetic helicity. The CME speeds were obtained
  from the SOHO/LASCO CME catalog (http://cdaw.gsfc.nasa.gov). We found
  that the magnetic helicity is positively correlated with the speed of
  CMEs. This result suggests that the magnetic helicity of CME source
  regions maybe useful for predicting CME speed.

---------------------------------------------------------
Title: X-ray Flare Durations and CME Associations
Authors: Yashiro, Seiji; Gopalswamy, N.; Akiyama, S.; Kahler, S.
2010shin.confE..86Y    Altcode:
  We report on a statistical study assessing how the soft X-ray flare
  durations affect the flare-CME relationship. To this end, we considered
  245 limb flares (central meridian distance &gt; 60 degrees) that had
  soft X-ray importance in the narrow range M1.0 to M3.0. We chose the
  limb flares to avoid projection effects and the CME visibility issues;
  the medium flares were considered to avoid the influence of flare peak
  intensity on CME parameters. We examined the CME association of these
  flares using coronal images obtained by SOHO/LASCO. We found that the
  CME association rate of flares slowly increases with increasing flare
  durations. All the flares with very long duration (T&gt;100 min) were
  associated with CMEs. However, 40% of the impulsive flares (T&lt;10
  min) were associated with CMEs, and 30% of the long-duration flares
  (60&lt;T&lt;100 min) did not have CME association. The duration
  distribution of flares with and without CMEs had a high degree of
  overlap. We conclude that the soft X-ray flare duration is not a good
  indicator of the CME association.

---------------------------------------------------------
Title: Type II radio emission and ESP events
Authors: Makela, Pertti; Gopalswamy, Nat; Akiyama, Sachiko; Xie,
   Hong; Yashiro, Seiji
2010shin.confE..87M    Altcode:
  We report on a survey of energetic storm particle (ESP) events
  associated with radio-quiet (RQ) and radio-loud (RL) interplanetary
  (IP) shocks observed during 1996-2006. Shocks were classified into
  RL or RQ events based on the existence of type II radio bursts. We
  consider only shocks driven by coronal mass ejections (CMEs). Particle
  observations are provided by the Electron, Proton and Alpha Monitor
  (EPAM) instrument on the Advanced Composition Explorer (ACE) spacecraft
  and the Energetic and Relativistic Nuclei and Electron (ERNE) experiment
  on the Solar and Heliospheric Observatoty (SOHO). We find that 32%
  of RQ shocks produced an ESP event at energies &gt;1.8 MeV, compared
  to 52% of RL shocks. Electron enhancements were detected in 20% of RQ
  shocks and 39% of RL shocks. The ESP events associated with RQ shocks
  are less intense than those associated with RL shocks. In addition, RQ
  shocks with ESP events are predominately quasi-perpendicular shocks,
  and their solar sources located generally to the east of the central
  meridian. The size of ESP increases showed a modest positive correlation
  with the CME and shock speeds and with the Alfvenic Mach number. Our
  results indicate that some RQ shocks can accelerate particles at 1 AU,
  but less efficiently than RL shocks, even though they do not produce
  observable type II radio bursts. This variability is probably related
  to differences in the shock formation in the low corona, changes in the
  properties of the shocks as they propagate through interplanetary space,
  and the escape efficiency of accelerated particles from the shock front.

---------------------------------------------------------
Title: Expansion speed of Coronal Mass Ejections
Authors: Michalek, Grzegorz; Gopalswamy, Nat; Yashiro, Seiji
2010EGUGA..12.5142M    Altcode:
  A large set of limb CMEs has been used to determine the accurate
  relationship between radial (V rad) and expansion (V exp) speeds of
  CMEs. It was demonstrated that this relation is exceptionally well
  described by the function f(w)= 1/2 (1 + cot (w)) representing a full
  cone model for the CME with a half width, w. We also demonstrated that
  this relation for the halo CMEs could be very simple V rad = V exp.

---------------------------------------------------------
Title: Large Geomagnetic Storms Associated with Limb Halo Coronal
    Mass Ejections
Authors: Gopalswamy, Nat; Yashiro, Seiji; Xie, Hong; Akiyama, Sachiko;
   Mäakelä, Pertti
2010aogs...21...71G    Altcode: 2009arXiv0903.2776G
  Solar cycle 23 witnessed the observation of hundreds of halo coronal
  mass ejections (CMEs), thanks to the high dynamic range and extended
  field of view of the Large Angle and Spectrometric Coronagraph (LASCO)
  on board the Solar and Heliospheric Observatory (SOHO) mission. More
  than two thirds of halo CMEs originating on the front side of the Sun
  have been found to be geoeffective (Dst ≤ -50 nT). The delay time
  between the onset of halo CMEs and the peak of ensuing geomagnetic
  storms has been found to depend on the solar source location
  (Gopalswamy et al., 2007). In particular, limb halo CMEs (source
  longitude &gt; 45°) have a 20% shorter delay time on the average. It
  was suggested that the geomagnetic storms due to limb halos must be
  due to the sheath portion of the interplanetary CMEs (ICMEs) so that
  the shorter delay time can be accounted for. We confirm this suggestion
  by examining the sheath and ejecta portions of ICMEs from Wind and ACE
  data that correspond to the limb halos. Detailed examination showed
  that three pairs of limb halos were interacting events. Geomagnetic
  storms following five limb halos were actually produced by other disk
  halos. The storms followed by four isolated limb halos and the ones
  associated with interacting limb halos, were all due to the sheath
  portions of ICMEs.

---------------------------------------------------------
Title: Polar Chromospheric Signatures of the Subdued Cycle 23/24
    Solar Minimum
Authors: Gopalswamy, N.; Yashiro, S.; Makela, P.; Shibasaki, K.;
   Hathaway, D.
2010AAS...21640103G    Altcode: 2010BAAS...41..857G
  Coronal holes appear brighter than the quiet Sun in microwave images,
  with a brightness enhancement of 500 to 2000 K. The brightness
  enhancement corresponds to the upper chromosphere, where the
  plasma temperature is about 10000 K. We constructed a microwave
  butterfly diagram using the synoptic images obtained by the Nobeyama
  radioheliograph (NoRH) showing the evolution of the polar and low
  latitude brightness temperature. While the polar brightness reveals the
  chromospheric conditions, the low latitude brightness is attributed to
  active regions in the corona. When we compared the microwave butterfly
  diagram with the magnetic butterfly diagram, we found a good correlation
  between the microwave brightness enhancement and the polar field
  strength. The microwave butterfly diagram covers part of solar cycle
  22, whole of cycle 23, and part of cycle 24, thus enabling comparison
  between the cycle 23/24 and cycle 22/23 minima. The microwave brightness
  during the cycle 23/24 minimum was found to be lower than that during
  the cycle 22/23 minimum by 250 K. The reduced brightness temperature
  is consistent with the reduced polar field strength during the cycle
  23/24 minimum seen in the magnetic butterfly diagram. We suggest that
  the microwave brightness at the solar poles is a good indicator of
  the speed of the solar wind sampled by Ulysses at high latitudes.

---------------------------------------------------------
Title: Radioheliograph Observations of Metric Type II Bursts and
    the Kinematics of Coronal Mass Ejections
Authors: Ramesh, R.; Kathiravan, C.; Kartha, Sreeja S.; Gopalswamy, N.
2010ApJ...712..188R    Altcode:
  Assuming that metric type II radio bursts from the Sun are due to
  magnetohydrodynamic shocks driven by coronal mass ejections (CMEs),
  we estimate the average CME acceleration from its source region up to
  the position of the type II burst. The acceleration values are in the
  range ≈600-1240 m s^{-2}, which are consistent with values obtained
  using non-radio methods. We also find that (1) CMEs with comparatively
  larger acceleration in the low corona are associated with soft X-ray
  flares of higher energy; the typical acceleration of a CME associated
  with X1.0 class soft X-ray flare being ≈ 1020 m s^{-2}, and (2)
  CMEs with comparatively higher speed in the low corona slow down
  quickly at large distances from the Sun—the deceleration of a CME
  with a typical speed of 1000 km s<SUP>-1</SUP> being ≈ -15 m s^{-2}
  in the distance range of ≈3-32 R <SUB>sun</SUB>.

---------------------------------------------------------
Title: Solar Sources of “Driverless” Interplanetary Shocks
Authors: Gopalswamy, N.; Mäkelä, P.; Xie, H.; Akiyama, S.;
   Yashiro, S.
2010AIPC.1216..452G    Altcode:
  We identify the solar sources of a large number of interplanetary
  (IP) shocks that do not have a discernible driver as observed by
  spacecraft along the Sun-Earth line. At the Sun, these “driverless”
  shocks are associated with fast and wide CMEs. Most of the CMEs were
  also driving shocks near the Sun, as evidenced by the association of
  IP type II radio bursts. Thus, all these shocks are driven by CMEs
  and they are not blast waves. Normally limb CMEs produce driverless
  shocks at 1 AU. But some disk-center CMEs also result in driverless
  shocks because of deflection by nearby coronal holes. We estimate the
  angular deflection to be in the range 20°-60°. We also compared the
  influence of nearby coronal holes on a set of CMEs that resulted in
  magnetic clouds. The influence is nearly three times larger in the
  case of driverless shocks, confirming the large deflection required.

---------------------------------------------------------
Title: The CME link to geomagnetic storms
Authors: Gopalswamy, Nat
2010IAUS..264..326G    Altcode:
  The coronal mass ejection (CME) link to geomagnetic storms stems from
  the southward component of the interplanetary magnetic field contained
  in the CME flux ropes and in the sheath between the flux rope and the
  CME-driven shock. A typical storm-causing CME is characterized by (i)
  high speed, (ii) large angular width (mostly halos and partial halos),
  and (iii) solar source location close to the central meridian. For
  CMEs originating at larger central meridian distances, the storms
  are mainly caused by the sheath field. Both the magnetic and energy
  contents of the storm-producing CMEs can be traced to the magnetic
  structure of active regions and the free energy stored in them.

---------------------------------------------------------
Title: Interplanetary Shocks Lacking Type II Radio Bursts
Authors: Gopalswamy, N.; Xie, H.; Mäkelä, P.; Akiyama, S.; Yashiro,
   S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. -L.
2010ApJ...710.1111G    Altcode: 2009arXiv0912.4719G
  We report on the radio-emission characteristics of 222 interplanetary
  (IP) shocks detected by spacecraft at Sun-Earth L1 during solar cycle
  23 (1996 to 2006, inclusive). A surprisingly large fraction of the IP
  shocks (~34%) was radio quiet (RQ; i.e., the shocks lacked type II radio
  bursts). We examined the properties of coronal mass ejections (CMEs)
  and soft X-ray flares associated with such RQ shocks and compared them
  with those of the radio-loud (RL) shocks. The CMEs associated with the
  RQ shocks were generally slow (average speed ~535 km s<SUP>-1</SUP>)
  and only ~40% of the CMEs were halos. The corresponding numbers for
  CMEs associated with RL shocks were 1237 km s<SUP>-1</SUP> and 72%,
  respectively. Thus, the CME kinetic energy seems to be the deciding
  factor in the radio-emission properties of shocks. The lower kinetic
  energy of CMEs associated with RQ shocks is also suggested by the
  lower peak soft X-ray flux of the associated flares (C3.4 versus
  M4.7 for RL shocks). CMEs associated with RQ CMEs were generally
  accelerating within the coronagraph field of view (average acceleration
  ~+6.8 m s<SUP>-2</SUP>), while those associated with RL shocks were
  decelerating (average acceleration ~-3.5 m s<SUP>-2</SUP>). This
  suggests that many of the RQ shocks formed at large distances from the
  Sun, typically beyond 10 Rs, consistent with the absence of metric and
  decameter—hectometric (DH) type II radio bursts. A small fraction
  of RL shocks had type II radio emission solely in the kilometric
  (km) wavelength domain. Interestingly, the kinematics of the CMEs
  associated with the km type II bursts is similar to those of RQ shocks,
  except that the former are slightly more energetic. Comparison of
  the shock Mach numbers at 1 AU shows that the RQ shocks are mostly
  subcritical, suggesting that they were not efficient in accelerating
  electrons. The Mach number values also indicate that most of these are
  quasi-perpendicular shocks. The radio-quietness is predominant in the
  rise phase and decreases through the maximum and declining phases of
  solar cycle 23. About 18% of the IP shocks do not have discernible
  ejecta behind them. These shocks are due to CMEs moving at large
  angles from the Sun-Earth line and hence are not blast waves. The solar
  sources of the shock-driving CMEs follow the sunspot butterfly diagram,
  consistent with the higher-energy requirement for driving shocks.

---------------------------------------------------------
Title: Prediction of the interplanetary Coronal Mass Ejection and
    it's associated shock by using neural network
Authors: Mahrous, Ayman; Radi, Amr; Youssef, Mohamed; Faheem, Amin;
   Ahmed, Safinaz; Gopalswamy, Nat
2010cosp...38.1905M    Altcode: 2010cosp.meet.1905M
  We determined the effective parameter that can be used to predict the
  estimated arrival time for both Interplanetary Coronal Mass Ejection
  (ICME) and its associated shock (using the list of Richardson/Cane ICMEs
  in 1996-2007). Neural network model is used to predict ICME/shock
  and its arrival time. The set of CME-IP shock pairs obtain from
  Richardson/Cane ICMEs list is used to construct our neural model from
  (1996-2005). Concurrently, we determined the effective parameter that
  used CME-IP shock pairs from (2005-2007) to test our neural networks
  model. We found that the model succeeded to predict 97

---------------------------------------------------------
Title: Quasi-Periodic Oscillations in Lasco Coronal Mass Ejection
    Speeds
Authors: Shanmugaraju, A.; Moon, Y. -J.; Cho, K. -S.; Bong, S. C.;
   Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Umapathy, S.; Vrsnak, B.
2010ApJ...708..450S    Altcode:
  Quasi-periodic oscillations in the speed profile of coronal mass
  ejections (CMEs) in the radial distance range 2-30 solar radii are
  studied. We considered the height-time data of the 307 CMEs recorded
  by the Large Angle and Spectrometric Coronagraph (LASCO) during 2005
  January-March. In order to study the speed-distance profile of the CMEs,
  we have used only 116 events for which there are at least 10 height-time
  measurements made in the LASCO field of view. The instantaneous CME
  speed is estimated using a pair of height-time data points, providing
  the speed-distance profile. We found quasi-periodic patterns in at
  least 15 speed-distance profiles, where the speed amplitudes are larger
  than the speed errors. For these events we have determined the speed
  amplitude and period of oscillations. The periods of quasi-periodic
  oscillations are found in the range 48-240 minutes, tending to
  increase with height. The oscillations have similar properties as
  those reported by Krall et al., who interpreted them in terms of the
  flux-rope model. The nature of forces responsible for the motion of
  CMEs and their oscillations are discussed.

---------------------------------------------------------
Title: Coronal Mass Ejections from Sunspot and Non-Sunspot Regions
Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Mäkelä, P.
2010ASSP...19..289G    Altcode: 2009arXiv0903.1087G; 2010mcia.conf..289G
  Coronal mass ejections (CMEs) originate from closed magnetic field
  regions on the Sun, which are active regions and quiescent filament
  regions. The energetic populations such as halo CMEs, CMEs associated
  with magnetic clouds, geoeffective CMEs, CMEs associated with
  solar energetic particles and interplanetary type II radio bursts,
  and shock-driving CMEs have been found to originate from sunspot
  regions. The CME and flare occurrence rates are found to be correlated
  with the sunspot number, but the correlations are significantly weaker
  during the maximum phase compared to the rise and declining phases. We
  suggest that the weaker correlation results from high-latitude CMEs
  from the polar crown filament regions that are not related to sunspots.

---------------------------------------------------------
Title: Estimation of coronal magnetic field using the type II radio
    burst associated with a fast CME
Authors: Gopalswamy, Nat; Yashiro, Seiji; Akiyama, Sachiko; Freeland,
   Samuel; Davila, Joseph; Howard, Russell; Bougeret, J. -L.
2010cosp...38.1808G    Altcode: 2010cosp.meet.1808G
  The 2008 March 25 coronal mass ejection (CME) was the second
  fastest among the 10 type II producing CMEs in the STEREO era. The
  CME was accompanied by a EUV wave and a shock discernible in the
  white-light data. The type II burst was observed in the metric and
  decameter-hectometer (DH) wavelength domains. The type II burst ended in
  the DH domain when the CME speed started declining at a heliocentric
  distance where the Alfven speed reached its peak value. Under the
  scenario that the type II burst was caused by a CME-driven shock,
  we see that the end of the type II burst corresponds to a significant
  weakening of the shock, making it subcritical. The standoff distance
  between the flux rope structure and the shock significantly increased at
  the time of the shock weakening. From the observed standoff distance,
  we estimated the upstream Alfvenic Mach number and hence the coronal
  magnetic field. The magnetic field derived (0.04 G) is consistent with
  typical quiet solar atmosphere at 7 solar radii.

---------------------------------------------------------
Title: Investigating the relation between Coronal Holes and CMEs
    during the Rise, Maximum and Declining Phases of the Solar Cycle 23
Authors: Shahin, Amaal; Gopalswamy, Nat
2010cosp...38.1918S    Altcode: 2010cosp.meet.1918S
  In a study on the interaction between Coronal holes (CHs) and inter
  planetary coronal mass ejections (ICMEs) during the declining phase
  of solar cycle 23, Gopalswamy et al. [2009] showed that coronal holes
  (CHs) act as a magnetic wall that constrains the CME propagation. The
  CME trajectories are significantly affected when the eruptions
  occur in close proximity to CHs. Here, we investigate the influence
  of coronal holes on the propagation of CMEs through considering both
  ICMEs categories with and without flux rope structures during the rise
  and maximum phases of the solar cycle 23. We also, compare the results
  obtained with that of the declining phase and of the driverless shocks
  reported previously by Gopalswamy et al. [2009]. A list of ICMEs that
  are not classified as MCs has been developed from the Interplanetary
  (IP) shock list of the solar cycle 23 via selecting all disk center
  events (central meridian distance 15o ) that have been observed
  to be (MC s) which leaves us with another list includes the non MC
  events. The influence of the CHs is computed as a fictitious force
  that depends on the CH area, the distance between the CH and the
  eruption region, and the magnetic field within the CH at photospheric
  level. The open magnetic field distribution on the Sun is obtained for
  the MCs and non MCs solar events studied during the rise and maximum
  phases in addition to four magnetic cloud events were not included
  in Goplaswamy et al. [2009]. This open filed distribution is obtained
  through performing a potential field source surface extrapolation to
  the corona up to a heliocentric distance of 2.5 Rs. The Correlation
  Coefficient (CC) between the duration of the ICMEs and the resultant
  influence parameter F of the coronal holes is determined in the case
  of MCs and non MCs for rise, maximum and declining phases. The results
  show that the correlation coefficient in the case of magnetic cloud
  (MCs) events is very high at the rise phase ( 0.84) which confirms the
  correspondence between the non radial motion during the rise phase of
  the solar cycle and the higher magnetic field strength in the solar
  regions of the polar coronal holes existed in this phase. The difference
  between measured position angle (MPA) and the influence position angle
  (FPA) where F is pointing, () for the non MCs in the rise and maximum
  phases is found to be 34o and 35o ; respectively which is consistent
  with that for driverless shocks given by Gopalswamy et al. [2009] (where
  37o ). These results together with the average influence parameter
  value (F av 2.53 G) for the declining phase which is found to be the
  highest compared to the other two phases and also to the MCs average
  values suggest that the non MCs are resembling in their behavior the
  driverless shocks (which have been proven by Gopalswamy et al., 2009
  to be deflected by the near by CH s away from the Sun-Earth line) and
  that the non MCs may have flux rope structure as the MCs do have but
  this structure is hidden from observation due to the deflection by CH
  s. This finding may have bearing on the idea that all CMEs may be flux
  ropes and the difference is only due to the viewing angle variation.

---------------------------------------------------------
Title: The International Space Weather Initiative
Authors: Davila, Joseph; Gopalswamy, Nat
2010cosp...38.4192D    Altcode: 2010cosp.meet.4192D
  The International Space Weather Initiative (ISWI) is an international
  program of scientific collaboration to understand the external drivers
  of space weather. One of the major thrusts of the ISWI is to deploy
  arrays of small instruments such as magnetometers, radio antennas, GPS
  receivers, all-sky cameras, particle detectors, etc. around the world to
  provide global measurements of heliospheric phenomena. Scientists from
  approximately 70 countries now participate in the instrument operation,
  data collection, analysis, and publication of scientific results,
  working at the forefront of science research. The purpose of the ISWI is
  to continue the scientific study of universal processes in the solar
  system that affect space weather and the terrestrial environment,
  and to continue to coordinate the deployment and operation of new and
  existing instrument arrays aimed at understanding the impacts of Space
  Weather on Earth and the near-Earth environment. This project provides
  an excellent opportunity for potential instrument providers to engage
  collaborators from specific geographical locations, and to broaden
  the coverage of existing instrument arrays. By deploying instruments
  in strategically chosen locations new science and a more global view
  of heliophysical processes is obtained. These data will also provide
  new inputs for global ionospheric models in the future.

---------------------------------------------------------
Title: Recent STEREO Observations of Coronal Mass Ejections
Authors: St Cyr, O. C.; Xie, H.; Mays, M. L.; Davila, J. M.; Gilbert,
   H. R.; Jones, S. I.; Pesnell, W. D.; Gopalswamy, N.; Gurman, J. B.;
   Yashiro, S.; Wuelser, J.; Howard, R. A.; Thompson, B. J.; Thompson,
   W. T.
2009AGUFMSH11A1491S    Altcode:
  Over 400 CMEs have been observed by STEREO SECCHI COR1 during
  the mission's three year duration (2006-2009). Many of the solar
  activity indicators have been at minimal values over this period,
  and the Carrington rotation-averaged CME rate has been comparable to
  that measured during the minima between Cycle 21-22 (SMM C/P) and
  Cycle 22-23 (SOHO LASCO). That rate is about 0.5 CMEs/day. During
  the current solar minimum (leading to Cycle 24), there have been
  entire Carrington rotations where no sunspots were detected and the
  daily values of the 2800 MHz solar flux remained below 70 sfu. CMEs
  continued to be detected during these exceptionally quiet periods,
  indicating that active regions are not necessary to the generation of
  at least a portion of the CME population. In the past, researchers were
  limited to a single view of the Sun and could conclude that activity
  on the unseen portion of the disk might be associated with CMEs. But
  as the STEREO mission has progressed we have been able to observe an
  increasing fraction of the Sun's corona with STEREO SECCHI EUVI and
  were able to eliminate this possibility. Here we report on the nature
  of CMEs detected during these exceptionally-quiet periods, and we
  speculate on how the corona remains dynamic during such conditions.

---------------------------------------------------------
Title: Expansion Speed of Coronal Mass Ejections
Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S.
2009SoPh..260..401M    Altcode:
  A large set of limb coronal mass ejections (CMEs) are used to
  determine the accurate relationship between radial (V<SUB>rad</SUB>)
  and expansion (V<SUB>exp</SUB>) speeds of CMEs. It is demonstrated
  that this relation is exceptionally well described by the function
  f(w)=1/2(1+cot w), representing a full cone model for the CME with
  a half-width, w. We also demonstrate that for extremely fast CMEs
  (V<SUB>exp</SUB>&gt;3000 km s<SUP>−1</SUP>), it is better to use the
  approximation V<SUB>rad</SUB>≈V<SUB>LE</SUB>. This implies that such
  CMEs expand spherically above the solar surface.

---------------------------------------------------------
Title: Relation between Magnetic Helicity and CME Speed in Source
    Active Regions
Authors: Jung, H.; Gopalswamy, N.; Akiyama, S.; Yashiro, S.
2009AGUFMSH41B1669J    Altcode:
  We report on a study linking the speed of coronal mass ejections
  (CMEs) to the magnetic helicity in the source active regions. The
  motivation comes from the fact that the CME speed may depend on the
  active region free magnetic energy, which in turn may be represented
  by the helicity, a proxy for the nonpotentiality. We selected a set
  of active regions from solar cycle 23, measured their helicity, and
  identified CMEs from the CME catalog (http://cdaw.gsfc.nasa.gov). Using
  EUV and magnetogram data from the Solar and Heliospheric Observatory
  (SOHO) mission, we measured the coronal helicity content before CME
  eruptions. We extrapolated the photospheric magnetic field to the
  corona to obtain the coronal helicity that fits a EUV image before
  each CME eruption. The CME speeds used here corresponds to the average
  speed within the SOHO coronagraphic field of view. We found that
  magnetic helicity is positively correlated with the speed of CME. We
  cross-checked the helicity values using the principle of magnetic
  helicity conservation connecting helicity obtained from the Local
  Correlation Tracking (LCT) method, the helicity of the associated
  magnetic clouds and the coronal helicity.

---------------------------------------------------------
Title: The 26 April 2008 CME; a Case Study Tracking a CME into
    the Heliosphere
Authors: Webb, D. F.; Galvin, A. B.; Gopalswamy, N.; Howard, T. A.;
   Reinard, A. A.; Jackson, B.; Davis, C.
2009AGUFMSH41A1640W    Altcode:
  With the current unique constellation of spacecraft, we are studying
  the origins of CMEs, their 3D structure and how they propagate through
  the heliosphere. Here we present the results of a case study of one
  well observed event that occurred during the Whole Heliosphere Interval
  (WHI), originating at the Sun on 26 April 2008. The event arose from a
  cluster of 3 active regions that evolved over several solar rotations
  centered on WHI. The CME was moderately fast with evidence of a shock
  and was associated with a coronal arcade, coronal dimming and an EUV
  wave. The April 26 CME originated from disk center for STEREO-B and
  apparently caused a small SEP event and shock and possible magnetic
  cloud at STEREO-B on April 29. A brief IP type II suggests that
  this event had the lowest starting frequency ever observed, which has
  implications for the medium through which the shock propagates. Possible
  ejecta was detected in situ at STEREO-B. The Fe charge states suggest
  that there was a CIR-type interface with some bidirectional electron
  streaming present. This is confirmed by SMEI 3D reconstructions of
  density indicating that the ICME interacted with a preexisting CIR. The
  ICME was also imaged by the SECCHI HI imagers; both the SMEI and HI
  data permit us to track the dense material from the Sun past 1 AU.

---------------------------------------------------------
Title: Interplanetary Proton and Electron Enhancements Associated
    with Radio-loud and Radio-quiet CME-driven Shocks
Authors: Makela, P. A.; Gopalswamy, N.; Xie, H.; Akiyama, S.;
   Yashiro, S.
2009AGUFMSH33A1477M    Altcode:
  We present the results on electron and proton acceleration in
  association with radio-quiet (RQ) and radio-loud (RL) shocks driven by
  coronal mass ejections (CMEs) during 1996-2006. The CME-driven shocks
  are classified into RL or RQ shocks based on the presence or the
  lack of type II radio bursts in the metric and decameter-hectometric
  wavelength range. We studied proton flux enhancements at L1 in the
  66 keV - 50 MeV energy range observed by the ACE/EPAM and SOHO/ERNE
  instruments. Electron flux enhancements were studied in the 38-53~keV
  energy channel of EPAM. In general, the RL shocks are more likely
  to be associated with an energetic storm particle (ESP) event than
  RQ shocks. Approximately one third of RQ shocks and slightly over a
  half of RL shocks produced an ESP event at energies above 1.8 MeV. In
  overall both RQ and RL electron ESP events are rarer, but they follow
  a similar pattern to the proton observations, i.e. ESP events are
  observed in approximately one fifth versus two fifths of shocks,
  respectively. We also studied correlations of ESP event size with CME
  and shock properties. As expected, the ESP events associated with the RQ
  shocks are less intense than those with RL shocks. In addition, particle
  acceleration in RQ shocks occurs predominately in quasi-perpendicular
  shocks. There is a modest positive correlation between ESP event size
  and the CME and shock speed and the Mach number. Again, the correlations
  are stronger for the RL shocks. It appears that shocks can accelerate
  particles, although less efficiently, even when they do not produce
  observable type II radio bursts. The variation between the presence
  of type IIs and ESP events is probably connected to variations in the
  coronal conditions of shock formation and to the consequent evolution
  of the shock as it travels through diverse coronal and interplanetary
  plasmas.

---------------------------------------------------------
Title: The subdued solar cycle 23/24 minimum revealed by microwave
    butterfly diagram
Authors: Gopalswamy, N.; Yashiro, S.; Makela, P. A.; Shibasaki, K.
2009AGUFMSH13C..02G    Altcode:
  The 17 GHz microwave brightness temperature in coronal holes
  is typically enhanced by 500 to 2000 K with respect to the quiet
  Sun. This is considered to be a property of the upper chromosphere,
  where the plasma temperature is ~10000 K. We constructed a microwave
  butterfly diagram using the synoptic images obtained by the Nobeyama
  Radioheliograph and compared it with the magnetic butterfly diagram. We
  found a good correlation between the microwave brightness enhancement
  and the polar field strength. We also performed a rotation-by-rotation
  comparison between the two data sets to obtain the correlation
  between the magnetic field strength and the microwave brightness
  temperature. The microwave butterfly diagram covers part of cycle
  22, whole of cycle 23, and part of cycle 24, thus enabling comparison
  between the cycle 23/24 and cycle 22/23 minima. The microwave brightness
  during the cycle 23/24 minimum was found to be lower than that during
  the cycle 22/23 minimum by ~250 K. The reduced brightness temperature
  is consistent with the reduced polar field strength during the cycle
  23/24 minimum seen e.g., in the SOHO/MDI magnetic butterfly diagram. We
  suggest that the microwave brightness at the solar poles is a good
  indicator of the speed of the solar wind sampled by Ulysses at high
  latitudes.

---------------------------------------------------------
Title: The relation between solar active region location and the
    lowest frequency of type III emission
Authors: Kuroda, N.; Gopalswamy, N.
2009AGUFMSH23A1522K    Altcode:
  We have investigated the relation between the lowest frequencies of type
  III bursts and the locations of source active regions from which the
  causal electron beams originate. We chose several active regions that
  produced coronal mass ejections (CMEs) and flares during their disk
  passage. The type III bursts considered in this study originated from
  these eruptions. The CMEs were detected by the Solar and Heliospheric
  Observatory (SOHO) mission’s Large Angle and Spectrometric coronagraph
  (LASCO). The type III bursts were observed by the Radio and Plasma
  Wave Experiment (WAVES) on board Wind. By tracking the type III bursts
  into the spectral range covered by the Thermal Noise Receiver (TNR)
  on board Wind, we were able to measure the lowest frequency reached
  by 104 type III bursts from 17 active regions. In addition, we were
  able to measure the frequency separation between the type III bursts
  and the local plasma frequency at the Wind spacecraft as measured by
  TNR. Because the type III bursts were produced when the source active
  regions were at various central meridian distances, we could study the
  lowest frequency at which the type III bursts occurred as a function
  of the source longitude. We found that the type III emission occurs
  at frequencies close to the local plasma frequency at the spacecraft
  when the source active regions are at the disk center or in the western
  hemisphere. Type III bursts from active regions close to the east limb
  of the Sun have a higher cutoff frequency. This can be explained by the
  fact that type III bursts from eastern active regions cannot propagate
  to the Wind spacecraft because of the intervening denser plasma regions
  Further investigation is needed to understand the large scatter in the
  data points, especially those that do not follow the expected tendency:
  a closer examination would reveal the condition of interplanetary medium
  and the state of solar wind at the time of these irregular points.

---------------------------------------------------------
Title: On the Origin, 3D Structure and Dynamic Evolution of CMEs
    Near Solar Minimum
Authors: Xie, H.; St. Cyr, O. C.; Gopalswamy, N.; Yashiro, S.; Krall,
   J.; Kramar, M.; Davila, J.
2009SoPh..259..143X    Altcode:
  We have conducted a statistical study 27 coronal mass ejections
  (CMEs) from January 2007 - June 2008, using the stereoscopic views
  of STEREO SECCHI A and B combined with SOHO LASCO observations. A
  flux-rope model, in conjunction with 3D triangulations, has been used
  to reconstruct the 3D structures and determine the actual speeds of
  CMEs. The origin and the dynamic evolution of the CMEs are investigated
  using COR1, COR2 and EUVI images. We have identified four types of
  solar surface activities associated with CMEs: i) total eruptive
  prominence (totEP), ii) partially eruptive prominence (PEP), iii)
  X-ray flare, and iv) X-type magnetic structure (X-line). Among the
  27 CMEs, 18.5% (5 of 27) are associated with totEPs, 29.6% (8 of 27)
  are associated with PEPs, 26% (7 of 27) are flare related, and 26%
  (7 of 27) are associated with X-line structures, and 43% (3 of 7)
  are associated with both X-line structures and PEPs. Three (11%)
  could not be associated with any detectable activity. The mean actual
  speeds for totEP-CMEs, PEP-CMEs, flare-CMEs, and X-line-CMEs are 404
  km s<SUP>−1</SUP>,247 km s<SUP>−1</SUP>,909 km s<SUP>−1</SUP>,
  and 276 km s<SUP>−1</SUP>, respectively; the average mean values of
  edge-on and broadside widths for the 27 CMEs are 52 and 85 degrees,
  respectively. We found that slow CMEs (V≤400 km s<SUP>−1</SUP>) tend
  to deflect towards and propagate along the streamer belts due to the
  deflections by the strong polar magnetic fields of corona holes, while
  some faster CMEs show opposite deflections away from the streamer belts.

---------------------------------------------------------
Title: Relation Between Type II Bursts and CMEs Inferred from STEREO
    Observations
Authors: Gopalswamy, N.; Thompson, W. T.; Davila, J. M.; Kaiser,
   M. L.; Yashiro, S.; Mäkelä, P.; Michalek, G.; Bougeret, J. -L.;
   Howard, R. A.
2009SoPh..259..227G    Altcode:
  The inner coronagraph (COR1) of the Solar Terrestrial Relations
  Observatory (STEREO) mission has made it possible to observe CMEs in
  the spatial domain overlapping with that of the metric type II radio
  bursts. The type II bursts were associated with generally weak flares
  (mostly B and C class soft X-ray flares), but the CMEs were quite
  energetic. Using CME data for a set of type II bursts during the
  declining phase of solar cycle 23, we determine the CME height when
  the type II bursts start, thus giving an estimate of the heliocentric
  distance at which CME-driven shocks form. This distance has been
  determined to be ∼1.5R<SUB>s</SUB> (solar radii), which coincides
  with the distance at which the Alfvén speed profile has a minimum
  value. We also use type II radio observations from STEREO/WAVES and
  Wind/WAVES observations to show that CMEs with moderate speed drive
  either weak shocks or no shock at all when they attain a height where
  the Alfvén speed peaks (∼3R<SUB>s</SUB> - 4R<SUB>s</SUB>). Thus
  the shocks seem to be most efficient in accelerating electrons in the
  heliocentric distance range of 1.5R<SUB>s</SUB> to 4R<SUB>s</SUB>. By
  combining the radial variation of the CME speed in the inner corona
  (CME speed increase) and interplanetary medium (speed decrease) we
  were able to correctly account for the deviations from the universal
  drift-rate spectrum of type II bursts, thus confirming the close
  physical connection between type II bursts and CMEs. The average height
  (∼1.5R<SUB>s</SUB>) of STEREO CMEs at the time of type II bursts
  is smaller than that (2.2R<SUB>s</SUB>) obtained for SOHO (Solar and
  Heliospheric Observatory) CMEs. We suggest that this may indicate,
  at least partly, the density reduction in the corona between the
  maximum and declining phases, so a given plasma level occurs closer
  to the Sun in the latter phase. In two cases, there was a diffuse
  shock-like feature ahead of the main body of the CME, indicating a
  standoff distance of 1R<SUB>s</SUB> - 2R<SUB>s</SUB> by the time the
  CME left the LASCO field of view.

---------------------------------------------------------
Title: Investigating the relation between coronal holes and CMEs
    during the rise phase of the solar cycle 23
Authors: Shahin, Amaal Abd-Alla; Gopalswamy, N.; Yashiro, S.; Akiyama,
   S.; Makela, P.; Xie, H.; Jung, H.
2009shin.confE.126S    Altcode:
  In a study on the interaction between CHs and ICMEs during the
  declining phase of solar cycle 23, Gopalswamy et al., (2009) showed
  that coronal holes (CHs) act as a magnetic wall that constrains the
  CME propagation. The CME trajectories are significantly affected when
  the eruptions occur in close proximity to CHs. Here, we extend this
  study to the rise phase of cycle 23. We consider the disk center CMEs
  (central meridian distance ?15o) that produced interplanetary shocks
  near Earth. We compute the influence of the CHs as a fictitious force
  that depends on the CH area, the distance between the CH and the
  eruption region, and the magnetic field within the CH at photospheric
  level. We compare the fictitious force acting on the CMEs to see if
  the appearance of the interplanetary counterparts of CMEs (ICMEs)
  is affected by the CHs.

---------------------------------------------------------
Title: Flux Rope CMEs Associated with Total and Partial Eruptive
    Prominences
Authors: Xie, Hong; Gilbert, H.; Gopalswamy, N.; St Cyr, O. C.
2009shin.confE.168X    Altcode:
  We present a statistical study involving 17 flux rope coronal mass
  ejections (CMEs) associated with 1) total eruptive prominence (TEP)
  and 2) partial eruptive prominence (PEP), observed by STEREO A and B. A
  flux rope model in conjunction with 3D triangulations has been used
  to reconstruct the 3D structures and determine the actual speeds of
  CMEs. The origins and the dynamic evolution of the CMEs are investigated
  using COR1 and COR2 coronagraphic images and EUVI images. Among the
  17 CMEs, 29% (5 of 17) are associated with TEPs, 71% (12 of 17)
  are associated with PEPs, and 58 % (7 of 12) are associated with
  both the X-line magnetic structures and PEPs. It is the first direct
  observations of the X-line structures in EUV images. For comparison,
  we also study 7 flare related CMEs, which occurred during January 2007
  - June 2008,;a CME is classified as a flare CME only when an A-class
  (or above) X-ray flare is reported by GOES. The mean actual speeds
  for TEP-CMEs, PEP-CMEs, X_line-CMEs, and flare CMEs are 404 km/s,
  255 km/s, 276 km/s, and 909 km/s respectively. It is found that the
  mean speed of TEP-CMEs is greater than that of PEP-CMEs but smaller
  than that of flare-CMEs. In addition, we found that there is a good
  anti- correlation between mass and speed among the 17 EP-CMEs with
  correlation coefficient r = -0.63. However, no such correlation exists
  among the 7 flare-CMEs. The results of this study are preliminary and
  we intend to extend this work for a larger number of events.

---------------------------------------------------------
Title: Numerical simulation of interchange reconnection based on
    the May 12, 1997 CME event
Authors: Cohen, Ofer; Schwadron, Nathan; Crooker, Nancy; Owens,
   Mathew; Gombosi, Tamas; Connick, D. E.; St Cyr, O. C.; Gopalswamy,
   N.; Yashiro, S.; Xie, H.
2009shin.confE.184C    Altcode:
  We perform a high-resolution MHD simulation of the May 12, 1997 CME
  event. We focus on the detailed three-dimensional evolution of the
  coronal magnetic field as the CME propagates through. Our goal is
  to identify interchange reconnection events between the CME and the
  ambient field and in particular, we try to quantify the the change in
  the distribution of the open magnetic flux due to the interaction of
  magnetic flux carried by the CME with the ambient open flux.

---------------------------------------------------------
Title: Erratum to “Solar sources and geospace consequences of
    interplanetary magnetic clouds observed during solar cycle 23—Paper
    1” [J. Atmos. Sol.-Terr. Phys. 70(2-4) (2008) 245-253]
Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.;
   Lepping, R. P.
2009JASTP..71.1005G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Properties of Solar Active Regions and Their Relationship
with Solar Eruption: a Statistical Study
Authors: Liu, Yang; Akiyama, S.; Gopalswamy, N.; Mason, J.; Nitta,
   N.; Tylka, A.; Yashiro, S.; Yurchyshyn, V.
2009SPD....40.0920L    Altcode:
  Using magnetograms taken by SOHO/MDI, we have calculated some parameters
  for solar active regions, and explored possible relationships between
  them and solar eruptions. The parameters of active regions we studied
  are magnetic flux, net flux, potential field energy, orientation
  and separation. We also estimated decay index of magnetic field
  overlying the neutral line, and the configuration of ambient field
  under which the active region sits. The data used were taken from
  1996 to 2005. With these results as a reference, we studied the active
  regions that produced the large solar energetic particle (SEP) events,
  or produced ground level enhancement (GLE) events. Comparison is also
  made between the active regions that produced full eruption and confine
  eruption (based on an event list published by Yashiro et al 2005, JGR,
  11012S05Y). We present our results here, together with a discussion.

---------------------------------------------------------
Title: Coronal mass ejections and space weather
Authors: Gopalswamy, N.
2009cwse.conf...77G    Altcode:
  Solar energetic particles (SEPs) and geomagnetic storms are the
  two primary space weather consequences of coronal mass ejections
  (CMEs) and their interplanetary counterparts (ICMEs). I summarize the
  observed properties of CMEs and ICMEs, paying particular attention to
  those properties that determine the ability of CMEs in causing space
  weather. Then I provide observational details of two the central issues:
  (i) for producing geomagnetic storms, the solar source location and
  kinematics along with the magnetic field structure and intensity are
  important, and (ii) for SEPs, the shock-driving ability of CMEs, the
  Alfven speed in the ambient medium, and the connectivity to Earth are
  crucial parameters

---------------------------------------------------------
Title: Halo coronal mass ejections and geomagnetic storms
Authors: Gopalswamy, Nat
2009EP&S...61..595G    Altcode: 2009EP&S...61L.595G
  In this letter, I show that the discrepancies in the geoeffectiveness of
  halo coronal mass ejections (CMEs) reported in the literature arise due
  to the varied definitions of halo CMEs used by different authors. In
  particular, I show that the low geoeffectiveness rate is a direct
  consequence of including partial halo CMEs. The geoeffectiveness of
  partial halo CMEs is lower because they are of low speed and likely
  to make a glancing impact on Earth.

---------------------------------------------------------
Title: The SOHO/LASCO CME Catalog
Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Stenborg, G.;
   Vourlidas, A.; Freeland, S.; Howard, R.
2009EM&P..104..295G    Altcode: 2009EM&P..tmp....8G
  Coronal mass ejections (CMEs) are routinely identified in the images
  of the solar corona obtained by the Solar and Heliospheric Observatory
  (SOHO) mission’s Large Angle and Spectrometric Coronagraph (LASCO)
  since 1996. The identified CMEs are measured and their basic attributes
  are cataloged in a data base known as the SOHO/LASCO CME Catalog. The
  Catalog also contains digital data, movies, and plots for each CME,
  so detailed scientific investigations can be performed on CMEs and
  the related phenomena such as flares, radio bursts, solar energetic
  particle events, and geomagnetic storms. This paper provides a brief
  description of the Catalog and summarizes the statistical properties
  of CMEs obtained using the Catalog. Data products relevant to space
  weather research and some CME issues that can be addressed using the
  Catalog are discussed. The URL of the Catalog is: &lt;ExternalRef&gt;
  &lt;RefSource&gt;http://cdaw.gsfc.nasa.gov/CME_list&lt;/RefSource&gt;
  &lt;RefTarget Address="http://cdaw.gsfc.nasa.gov/CME_list"
  TargetType="URL"/&gt; &lt;/ExternalRef&gt;.

---------------------------------------------------------
Title: Preface to the Proceedings of the European General Assembly
    and the United Nations Workshop
Authors: Gopalswamy, N.; Eichhorn, G.; Sakurai, T.; Haubold, H. J.
2009EM&P..104..139G    Altcode: 2009EM&P..tmp....4G
  No abstract at ADS

---------------------------------------------------------
Title: Statistical relationship between solar flares and coronal
    mass ejections
Authors: Yashiro, Seiji; Gopalswamy, Nat
2009IAUS..257..233Y    Altcode:
  We report on the statistical relationships between solar flares and
  coronal mass ejections (CMEs) observed during 1996-2007 inclusively. We
  used soft X-ray flares observed by the Geostationary Operational
  Environmental Satellite (GOES) and CMEs observed by the Large Angle and
  Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric
  Observatory (SOHO) mission. Main results are (1) the CME association
  rate increases with flare's peak flux, fluence, and duration, (2) the
  difference between flare and CME onsets shows a Gaussian distribution
  with the standard deviation σ = 17 min (σ = 15 min) for the first
  (second) order extrapolated CME onset, (3) the most frequent flare site
  is under the center of the CME span, not near one leg (outer edge) of
  the CMEs, (4) a good correlation was found between the flare fluence
  versus the CME kinetic energy. Implications for flare-CME models
  are discussed.

---------------------------------------------------------
Title: Modeling and prediction of fast CME/shocks associated with
    type II bursts
Authors: Xie, H.; Gopalswamy, N.; Cyr, O. C. St.
2009IAUS..257..489X    Altcode:
  A numerical simulation with ENLIL+Cone model was carried out to study
  the propagation of the shock driven by the 2005 May 13 CME. We then
  conducted a statistical analysis on a subset of similar events, where
  a decameter-hectometric (DH) type II radio burst and a counterpart
  kilometric type II have been observed to be associated with each CME
  (DHkm CME). The simulation results show that fast CME-driven shocks
  experienced a rapid deceleration as they propagated through the
  corona and then kept a nearly constant speed traveling out into the
  heliosphere. Two improved methods are proposed to predict the fast
  CME-driven shock arrival time, which give the prediction errors of
  3.43 and 6.83 hrs, respectively.

---------------------------------------------------------
Title: SEPs and CMEs during cycle 23
Authors: Mäkelä, Pertti; Gopalswamy, Nat; Yashiro, Seiji; Akiyama,
   Sachiko; Xie, Hong; Valtonen, Eino
2009IAUS..257..475M    Altcode:
  We present a study of solar energetic particles (SEPs) in association
  with coronal mass ejections (CMEs) and type II radio bursts. The
  particle and CME observations cover the years 1996-2007. We find that
  heavy-ion events in association with type II bursts and proton events
  are produced in more western and most energetic CMEs. In addition,
  the source distribution of type II associated proton events with heavy
  ions reminds the source distribution expected for events with flare
  particles. Therefore, the estimation of relative contributions by
  flares and shocks in SEP events and separation of suggested different
  particle acceleration models is complicated.

---------------------------------------------------------
Title: CME interactions with coronal holes and their interplanetary
    consequences
Authors: Gopalswamy, N.; Mäkelä, P.; Xie, H.; Akiyama, S.;
   Yashiro, S.
2009JGRA..114.0A22G    Altcode: 2009JGRA..11400A22G
  A significant number of interplanetary shocks (~17%) during cycle
  23 were not followed by drivers. The number of such “driverless”
  shocks steadily increased with the solar cycle with 15%, 33%, and
  52% occurring in the rise, maximum, and declining phase of the solar
  cycle. The solar sources of 15% of the driverless shocks were very
  close the central meridian of the Sun (within ~15°), which is quite
  unexpected. More interestingly, all the driverless shocks with their
  solar sources near the solar disk center occurred during the declining
  phase of solar cycle 23. When we investigated the coronal environment
  of the source regions of driverless shocks, we found that in each case
  there was at least one coronal hole nearby, suggesting that the coronal
  holes might have deflected the associated coronal mass ejections (CMEs)
  away from the Sun-Earth line. The presence of abundant low-latitude
  coronal holes during the declining phase further explains why CMEs
  originating close to the disk center mimic the limb CMEs, which normally
  lead to driverless shocks due to purely geometrical reasons. We also
  examined the solar source regions of shocks with drivers. For these,
  the coronal holes were located such that they either had no influence on
  the CME trajectories, or they deflected the CMEs toward the Sun-Earth
  line. We also obtained the open magnetic field distribution on the
  Sun by performing a potential field source surface extrapolation to
  the corona. It was found that the CMEs generally move away from the
  open magnetic field regions. The CME-coronal hole interaction must be
  widespread in the declining phase and may have a significant impact
  on the geoeffectiveness of CMEs.

---------------------------------------------------------
Title: Introduction to special section on Large Geomagnetic Storms
Authors: Gopalswamy, N.
2009JGRA..114.0A00G    Altcode: 2009JGRA..11400A00G
  Solar cycle 23 witnessed the accumulation of rich data sets that reveal
  various aspects of geomagnetic storms in unprecedented detail both at
  the Sun where the storm-causing disturbances originate and in geospace
  where the effects of the storms are directly felt. During two recent
  coordinated data analysis workshops (CDAWs) the large geomagnetic
  storms (Dst &lt;= -100 nT) of solar cycle 23 were studied in order to
  understand their solar, interplanetary, and geospace connections. This
  special section grew out of these CDAWs with additional contributions
  relevant to these storms. Here I provide a brief summary of the results
  presented in the special section.

---------------------------------------------------------
Title: Major solar flares without coronal mass ejections
Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S.
2009IAUS..257..283G    Altcode:
  We examine the source properties of X-class soft X-ray flares that
  were not associated with coronal mass ejections (CMEs). All the flares
  were associated with intense microwave bursts implying the production
  of high energy electrons. However, most (85%) of the flares were not
  associated with metric type III bursts, even though open field lines
  existed in all but two of the active regions. The X-class flares seem
  to be truly confined because there was no material ejection (thermal
  or nonthermal) away from the flaring region into space.

---------------------------------------------------------
Title: Universal processes in heliophysics
Authors: Davila, Joseph M.; Gopalswamy, Nat; Thompson, Barbara J.
2009IAUS..257...11D    Altcode:
  The structure of the Universe is determined primarily by the interplay
  of gravity which is dominant in condensed objects, and the magnetic
  force which is dominant in the rarefied medium between condensed
  objects. Each of these forces orders the matter into a set of
  characteristic structures each with the ability to store and release
  energy in response to changes in the external environment. For the
  most part, the storage and release of energy proceeds through a number
  of Universal Processes. The coordinated study of these processes in
  different settings provides a deeper understanding of the underlying
  physics governing Universal Processes in astrophysics.

---------------------------------------------------------
Title: Universal Heliophysical Processes
Authors: Gopalswamy, N.; Webb, D. F.
2009IAUS..257.....G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Evolution of the anemone AR NOAA 10798 and the related
    geo-effective flares and CMEs
Authors: Asai, Ayumi; Shibata, Kazunari; Ishii, Takako T.; Oka,
   Mitsuo; Kataoka, Ryuho; Fujiki, Ken'ichi; Gopalswamy, Nat
2009JGRA..114.0A21A    Altcode: 2009JGRA..11400A21A; 2008arXiv0812.2063A
  We present a detailed examination of the features of the active region
  (AR) NOAA 10798. This AR generated coronal mass ejections (CMEs) that
  caused a large geomagnetic storm on 24 August 2005 with the minimum Dst
  index of -216 nT. We examined the evolution of the AR and the features
  on/near the solar surface and in the interplanetary space. The AR
  emerged in the middle of a small coronal hole, and formed a sea anemone
  like configuration. Hα filaments were formed in the AR, which have
  southward axial field. Three M class flares were generated, and the
  first two that occurred on 22 August 2005 were followed by Halo-type
  CMEs. The speeds of the CMEs were fast, and recorded about 1200 and
  2400 km s<SUP>-1</SUP>, respectively. The second CME was especially
  fast, and caught up and interacted with the first (slower) CME during
  their travelings toward Earth. These acted synergically to generate
  an interplanetary disturbance with strong southward magnetic field of
  about -50 nT, which was followed by the large geomagnetic storm.

---------------------------------------------------------
Title: EUV Wave Reflection from a Coronal Hole
Authors: Gopalswamy, N.; Yashiro, S.; Temmer, M.; Davila, J.; Thompson,
   W. T.; Jones, S.; McAteer, R. T. J.; Wuelser, J. -P.; Freeland, S.;
   Howard, R. A.
2009ApJ...691L.123G    Altcode:
  We report on the detection of EUV wave reflection from a coronal
  hole, as observed by the Solar Terrestrial Relations Observatory
  mission. The EUV wave was associated with a coronal mass ejection
  (CME) erupting near the disk center. It was possible to measure the
  kinematics of the reflected waves for the first time. The reflected
  waves were generally slower than the direct wave. One of the important
  implications of the wave reflection is that the EUV transients are
  truly a wave phenomenon. The EUV wave reflection has implications for
  CME propagation, especially during the declining phase of the solar
  cycle when there are many low-latitude coronal holes.

---------------------------------------------------------
Title: The Expansion and Radial Speeds of Coronal Mass Ejections
Authors: Gopalswamy, N.; Dal Lago, A.; Yashiro, S.; Akiyama, S.
2009CEAB...33..115G    Altcode:
  We show the relation between radial (V_{rad}) and expansion (V_{exp})
  speeds of coronal mass ejections (CMEs) depends on the CME width. As
  CME width increases, {V_{rad}/V_{exp}} decreases from a value &gt;1
  to &lt;1. For widths approaching 180°, the ratio approaches 0 if the
  cone has a flat base, while it approaches 0.5 if the base has a bulge
  (ice cream cone). The speed difference between the limb and disk halos
  and the spherical expansion of super fast CMEs can be explained by
  the width dependence.

---------------------------------------------------------
Title: On the Characteristics of Shocks driven by limb CMEs
Authors: Xie, H.; Gopalswamy, N.; Stcyr, C.
2008AGUFMSH23B1650X    Altcode:
  We investigate the characteristics of bow shocks driven by limb
  CMEs near the Sun, including speed, width, compression ratio, and
  the relationshipof the standoff distance with CME size (the radius
  of curvature of a CME) and shock Mach number. We choose a subset of
  limb CMEs with distinct association of the decameter- hectometric (DH)
  type II burst, which is a good evidence of the existence CME-driven
  shock. The DH spectral domain corresponds to plasma frequencies within
  the field view of the SOHO/LASCO coronagraphs. Choosing limb events
  has several advantages: 1) there is no projection effects for CME
  speed measurements, 2) it is easier to determine the width of a CME
  and the front bow shock, 3) there is high confidence level for the
  plasma density determination from the white-light CME brightness. By
  studying the shock stand off distance and compression ratio, we obtain
  the shock Mach number and the Alfven speed profile in the corona.

---------------------------------------------------------
Title: Difference Between Magnetic Clouds and Non-cloud Ejecta in
    the Interplanetary Medium
Authors: Gopalswamy, N.
2008AGUFMSH22A..01G    Altcode:
  Solar cycle 23 has witnessed the accumulation of data on an
  unprecedented number of coronal mass ejections (CMEs) at the Sun and in
  the interplanetary (IP) medium, thanks to the large array of spaceborne
  observatories such as SOHO, Wind, and ACE. These observations have
  helped us make significant progress on the structure and evolution of
  CMEs in the inner heliosphere. One important question is whether the
  magnetic cloud (MC) and non-cloud ejecta have any difference in their
  solar origin. The ubiquitous nature of post-eruption arcades suggests
  that there should not be any difference. However, CMEs associated
  with MCs all originate from very close to the solar disk center
  (both in latitude and longitude). To zeroth order, the non-cloud
  ejecta seem to originate at larger central meridian distances
  (CMDs). In the extreme case of shocks without discernible ejecta,
  the corresponding CMEs have their solar sources near the limb. These
  observations suggest that whether one observes a flux rope (MC) or
  not depends mainly on the location of the observer with respect to the
  Sun-Earth line. Observations from solar cycle 23 indicate that there
  are significant deviations from the zeroth order picture, especially
  for non-cloud ejecta and the "driverless shocks": their solar sources
  near the disk center. The question is whether these ejecta do not have
  flux-rope structure by birth or they somehow got deflected away from the
  Sun-Earth line by other large- scale structures in the IP medium. The
  latter seems to be true for at least a subset of events, which seems to
  be affected by coronal holes located between the eruption center and
  the Sun-Earth line. This needs to be checked for all the events that
  deviate from the zeroth order picture. Charge-state signatures of MCs
  and non-cloud ejecta also support such a picture: the solar sources of
  IP CMEs with high charge states seem to originate close to the disk
  center, similar to the MC-associated CMEs. Another piece of evidence
  comes from the high correspondence between halo CMEs and MCs, both of
  which are highly geoeffective. Halo CMEs originating at larger CMDs
  produce geomagnetic storms via their sheath fields, again pointing to
  the importance of geometry. Contrary to importance of internal structure
  of CMEs for geoeffectiveness, the production of gradual solar energetic
  particle (SEP) should not depend on the internal structure of CMEs if
  the particles are accelerated by CME-driven shocks. In fact, there is
  a significant difference in the source distribution of SEP-producing
  CMEs (western sources) and MC CMEs (close to disk center). This paper
  illustrates these results using coronal and IP data.

---------------------------------------------------------
Title: Relation between Coronal Mass Ejection, Type II Radio Burst,
    and EUV Wave during the 2008 March 25 STEREO Event
Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Freeland, S.;
   Thompson, W. T.; Davila, J. M.; Howard, R. A.; Kaiser, M. L.; Bougeret,
   J. -
2008AGUFMSH12A..02G    Altcode:
  STEREO and SOHO observations of the March 25, 2008 coronal mass ejection
  (CME) provide an excellent opportunity to study its early evolution
  from multiple view points. The CME was fast (980 km/s) and wide (112
  degrees) from the east limb of the Sun as viewed by SOHO. The STEREO
  spacecraft were separated by about 50 degrees, so the CME was a disk
  event for the STEREO-behind spacecraft and a behind-the-limb event
  for STEREO-ahead. The CME was associated with a well defined EUV wave
  as observed by the STEREO/EUVI instrument, a metric type II burst,
  and a multi-component type II burst observed by the STEREO/WAVES and
  Wind/WAVES instruments. One of the important aspect of this CME is
  that it was well observed by STEREO/SECCHI inner coronagraph (COR1)
  when the metric type II burst was in progress, so we are able to obtain
  the shock height with respect t the CME. This enabled us to infer the
  connection the coronal shock driven by the CME (inferred from type II
  burst) and the EUV wave. It appears that the EUV wave steepened into
  a shock and produced the type II burst. The multiple components of
  the type II burst were not harmonically related, so we examined the
  circumstances of the eruption. CME was ejected in the region between
  two streamers, so the CME-driven shock is likely to simultaneously
  encounter high and low- density regions of the corona, thus producing
  type II bursts at widely separated frequencies. This paper summarizes
  these observations and explains how the CME, type II radio burst,
  and EUV waves all fit together.

---------------------------------------------------------
Title: Outreach activities during the 2006 total solar eclipse
    sponsored by the International Heliophysical Year
Authors: Rabello Soares, M. C.; Rabiu, A. B.; Gopalswamy, N.; Thompson,
   B. J.; Davila, J. M.; Sobrinho, A. A.
2008AdSpR..42.1792R    Altcode:
  The International Heliophysical Year (IHY) is an international program
  of scientific research to advance our understanding of the physical
  processes that govern the Sun, Earth and heliosphere. It has a strong
  educational component, linking research and education. Here, we describe
  the outreach activities during the 2006 total solar eclipse sponsored
  by IHY.

---------------------------------------------------------
Title: Conservation of open solar magnetic flux and the floor in
    the heliospheric magnetic field
Authors: Owens, M. J.; Crooker, N. U.; Schwadron, N. A.; Horbury,
   T. S.; Yashiro, S.; Xie, H.; St. Cyr, O. C.; Gopalswamy, N.
2008AGUFMSH12A..05O    Altcode:
  The near-Earth heliospheric magnetic field intensity, |B|, exhibits a
  strong solar cycle variation, but returns to the same "floor" value each
  solar minimum. The current minimum, however, has seen |B| drop below
  previous minima, bringing in to question the existence of a floor, or
  at the very least requiring a re-assessment of its value. In this study
  we assume heliospheric flux consists of a constant open flux component
  and a time-varying contribution from CMEs. In this scenario, the true
  floor is |B| with zero CME contribution. Using observed CME rates over
  the solar cycle, we estimate the "no-CME" |B| floor at ~4.2± 0.5 nT,
  lower than previous floor estimates and below |B| observed this solar
  minimum. We speculate that the drop in |B| observed this minimum may be
  due to a persistently lower CME rate than the previous minimum, though
  there are large uncertainties in the supporting observational data.

---------------------------------------------------------
Title: Solar connections of geoeffective magnetic structures
Authors: Gopalswamy, N.
2008JASTP..70.2078G    Altcode:
  Coronal mass ejections (CMEs) and high-speed solar wind streams
  (HSS) are two solar phenomena that produce large-scale structures in
  the interplanetary (IP) medium. CMEs evolve into interplanetary CMEs
  (ICMEs) and the HSS result in corotating interaction regions (CIRs) when
  they interact with preceding slow solar wind. This paper summarizes the
  properties of these structures and describes their geoeffectiveness. The
  primary focus is on the intense storms of solar cycle 23 because
  this is the first solar cycle during which simultaneous, extensive,
  and uniform data on solar, IP, and geospace phenomena exist. After
  presenting illustrative examples of coronal holes and CMEs, I discuss
  the internal structure of ICMEs, in particular the magnetic clouds
  (MCs). I then discuss how the magnetic field and speed correlate in the
  sheath and cloud portions of ICMEs. CME speed measured near the Sun also
  has significant correlations with the speed and magnetic field strengths
  measured at 1 AU. The dependence of storm intensity on MC, sheath, and
  CME properties is discussed pointing to the close connection between
  solar and IP phenomena. I compare the delay time between MC arrival
  at 1 AU and the peak time of storms for the cloud and sheath portions
  and show that the internal structure of MCs leads to the variations
  in the observed delay times. Finally, we examine the variation of
  solar-source latitudes of IP structures as a function of the solar
  cycle and find that they have to be very close to the disk center.

---------------------------------------------------------
Title: Conservation of open solar magnetic flux and the floor in
    the heliospheric magnetic field
Authors: Owens, M. J.; Crooker, N. U.; Schwadron, N. A.; Horbury,
   T. S.; Yashiro, S.; Xie, H.; St. Cyr, O. C.; Gopalswamy, N.
2008GeoRL..3520108O    Altcode:
  The near-Earth heliospheric magnetic field intensity, |B|, exhibits
  a strong solar cycle variation, but returns to the same “floor”
  value each solar minimum. The current minimum, however, has seen |B|
  drop below previous minima, bringing in to question the existence of a
  floor, or at the very least requiring a re-assessment of its value. In
  this study we assume heliospheric flux consists of a constant open
  flux component and a time-varying contribution from CMEs. In this
  scenario, the true floor is |B| with zero CME contribution. Using
  observed CME rates over the solar cycle, we estimate the “no-CME”
  |B| floor at ~4.0 +/- 0.3 nT, lower than previous floor estimates and
  below |B| observed this solar minimum. We speculate that the drop in
  |B| observed this minimum may be due to a persistently lower CME rate
  than the previous minimum, though there are large uncertainties in
  the supporting observational data.

---------------------------------------------------------
Title: International Heliophysical Year 2007: A Report from the
    UN/NASA Workshop Bangalore, India, 27 November 1 December 2006
Authors: Davila, Joe; Gopalswamy, Nat; Thompson, Barbara; Haubold,
   Hans J.
2008EM&P..103....9D    Altcode: 2008EM&P..tmp...19D
  The IHY Secretariat and the United Nations Basic Space Science
  Initiative (UNBSSI) assist scientists and engineers from all over the
  world in participating in the International Heliophysical Year (IHY)
  2007. A major thrust of IHY/UNBSSI is to deploy arrays of small,
  inexpensive instruments such as magnetometers, radio telescopes,
  GPS receivers, all-sky cameras, etc. around the world to allow
  global measurements of ionospheric and heliospheric phenomena. The
  small instrument programme is envisioned as a partnership between
  instrument providers and instrument hosts in developing nations. The
  IHY/UNBSSI can facilitate the deployment of several of these networks
  world-wide. Existing data bases and relevant software tools will
  be identified to promote space science activities in developing
  nations. Extensive data on space science have been accumulated by a
  number of space missions. Similarly, long-term data bases are available
  from ground-based observations. These data can be utilized in ways
  different from originally intended for understanding the heliophysical
  processes. This paper provides a comprehensive overview of IHY/UNBSSI,
  its achievements, future plans, and outreach to the 192 Member States
  of the United Nations as recorded in the UN/NASA workshop in India.

---------------------------------------------------------
Title: Coronal mass ejections, type II radio bursts, and solar
    energetic particle events in the SOHO era
Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Mäkelä, P.; Xie,
   H.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. L.
2008AnGeo..26.3033G    Altcode:
  Using the extensive and uniform data on coronal mass ejections (CMEs),
  solar energetic particle (SEP) events, and type II radio bursts during
  the SOHO era, we discuss how the CME properties such as speed, width
  and solar-source longitude decide whether CMEs are associated with type
  II radio bursts and SEP events. We discuss why some radio-quiet CMEs
  are associated with small SEP events while some radio-loud CMEs are
  not associated with SEP events. We conclude that either some fast and
  wide CMEs do not drive shocks or they drive weak shocks that do not
  produce significant levels of particle acceleration. We also infer
  that the Alfvén speed in the corona and near-Sun interplanetary
  medium ranges from &lt;200 km/s to ~1600 km/s. Radio-quiet fast
  and wide CMEs are also poor SEP producers and the association rate
  of type II bursts and SEP events steadily increases with CME speed
  and width (i.e. energy). If we consider western hemispheric CMEs,
  the SEP association rate increases linearly from ~30% for 800 km/s
  CMEs to 100% for ≥1800 km/s. Essentially all type II bursts in the
  decametre-hectometric (DH) wavelength range are associated with SEP
  events once the source location on the Sun is taken into account. This
  is a significant result for space weather applications, because if a
  CME originating from the western hemisphere is accompanied by a DH type
  II burst, there is a high probability that it will produce an SEP event.

---------------------------------------------------------
Title: A comparison of coronal mass ejections identified by manual
    and automatic methods
Authors: Yashiro, S.; Michalek, G.; Gopalswamy, N.
2008AnGeo..26.3103Y    Altcode:
  Coronal mass ejections (CMEs) are related to many phenomena
  (e.g. flares, solar energetic particles, geomagnetic storms), thus
  compiling of event catalogs is important for a global understanding
  these phenomena. CMEs have been identified manually for a long time,
  but in the SOHO era, automatic identification methods are being
  developed. In order to clarify the advantage and disadvantage of the
  manual and automatic CME catalogs, we examined the distributions of
  CME properties listed in the CDAW (manual) and CACTus (automatic)
  catalogs. Both catalogs have a good agreement on the wide CMEs
  (width&gt;120°) in their properties, while there is a significant
  discrepancy on the narrow CMEs (width≤30°): CACTus has a larger
  number of narrow CMEs than CDAW. We carried out an event-by-event
  examination of a sample of events and found that the CDAW catalog
  have missed many narrow CMEs during the solar maximum. Another
  significant discrepancy was found on the fast CMEs (speed&gt;1000
  km/s): the majority of the fast CDAW CMEs are wide and originate from
  low latitudes, while the fast CACTus CMEs are narrow and originate
  from all latitudes. Event-by-event examination of a sample of events
  suggests that CACTus has a problem on the detection of the fast CMEs.

---------------------------------------------------------
Title: Comment on “Prediction of the 1-AU arrival times of
CME-associated interplanetary shocks: Evaluation of an empirical
    interplanetary shock propagation model” by K.-H. Kim et al.
Authors: Gopalswamy, N.; Xie, H.
2008JGRA..11310105G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Type II Radio Emission and Solar Energetic Particle Events
Authors: Gopalswamy, Nat
2008AIPC.1039..196G    Altcode:
  Type II radio bursts, solar energetic particle (SEP) events, and
  interplanetary (IP) shocks all have a common cause, viz., fast and
  wide (speed &gt;=900 km/s and width &gt;=60°)) coronal mass ejections
  (CMEs). Deviations from this general picture are observed as (i) lack
  of type II bursts during many fast and wide CMEs and IP shocks, (ii)
  slow CMEs associated with type II bursts and SEP events, and (iii)
  lack of SEP events during many type II bursts. I examine the reasons
  for these deviations. I also show that ground level enhancement (GLE)
  events are consistent with shock acceleration because a type II burst
  is present in every event well before the release of GLE particles
  and SEPs at the Sun.

---------------------------------------------------------
Title: Synthetic radio maps of CME-driven shocks below 4 solar radii
    heliocentric distance
Authors: Schmidt, J. M.; Gopalswamy, N.
2008JGRA..113.8104S    Altcode:
  We present 2 1/2 D numerical MagnetoHydroDynamic (MHD) simulations of
  coronal mass ejections (CMEs) in conjunction with plasma simulations
  of radio emission from the CME-driven shocks. The CME-driven shock
  extends to an almost spherical shape during the temporal evolution of
  the CME. Our plasma simulations can reproduce the dynamic spectra
  of coronal type II radio bursts, with the frequency drift rates
  corresponding to the shock speeds. We find further, that the CME-driven
  shock is an effective radio emitter at metric wavelengths, when the
  CME has reached a heliocentric distance of about two solar radii
  (?). We apply our simulation results to explain the radio images of
  type II bursts obtained by radio heliographs, in particular to the
  banana-shaped images of radio sources associated with fast CMEs.

---------------------------------------------------------
Title: Investigation of CME dynamics in the LASCO field of view
Authors: Shanmugaraju, A.; Moon, Y. -J.; Cho, K. -S.; Gopalswamy,
   N.; Umapathy, S.
2008A&A...484..511S    Altcode:
  Context: The speed-distance profile of CMEs is important for
  understanding the propagation of CMEs. <BR />Aims: Our main aim is
  to study the initial speed of CMEs in the LASCO field of view and
  its role in subsequent CME propagation using the acceleration-speed
  profile. The secondary aim is to obtain the speed growth rate. <BR
  />Methods: We considered the height-time data of 307 CMEs observed by
  SOHO/LASCO during January-March 2005. To study the CME speed profile,
  we used only 116 events for which there were at least 10 height-time
  measurements in the LASCO field of view. Using this data, we obtained
  their initial speed, extrapolated initial speed, and growth rate. <BR
  />Results: The following results were found from this analysis. (i)
  The initial speed obtained from the first two data points is in the
  range 24-1208 km s<SUP>-1</SUP>, which is nearly similar to the
  range of linear speed (67-920 km s<SUP>-1</SUP>) obtained from a
  least squares fit through the entire h-t data set for each CME. (ii)
  However, the initial speed or extrapolated initial speed is much
  better correlated with acceleration and growth rate than the linear
  speed. (iii) Nearly two thirds of the events (74/116) are found to be
  accelerating. (iv) The speed growth rate is within the range -0.058
  to 0.061 × 10<SUP>-3</SUP> s<SUP>-1</SUP>, and it decreases with the
  distance. (v) The final observed distance in the LASCO field of view
  depends very weakly upon the initial speed, or extrapolated initial
  speed whereas it depends strongly on the linear speed. The above
  results demonstrate the role played by the initial speed of the CMEs.

---------------------------------------------------------
Title: Plasma Radiation and Acceleration Effectiveness of CME-driven
    Shocks
Authors: Gopalswamy, N.; Schmidt, J. M.
2008AGUSMSH41A..18G    Altcode:
  CME-driven shocks are effective radio radiation generators and
  accelerators for Solar Energetic Particles (SEPs). We present simulated
  3 D time-dependent radio maps of second order plasma radiation generated
  by CME- driven shocks. The CME with its shock is simulated with the
  3 D BATS-R-US CME model developed at the University of Michigan. The
  radiation is simulated using a kinetic plasma model that includes
  shock drift acceleration of electrons and stochastic growth theory of
  Langmuir waves. We find that in a realistic 3 D environment of magnetic
  field and solar wind outflow of the Sun the CME-driven shock shows a
  detailed spatial structure of the density, which is responsible for
  the fine structure of type II radio bursts. We also show realistic
  3 D reconstructions of the magnetic cloud field of the CME, which
  is accelerated outward by magnetic buoyancy forces in the diverging
  magnetic field of the Sun. The CME-driven shock is reconstructed by
  tomography using the maximum jump in the gradient of the entropy. In the
  vicinity of the shock we determine the Alfven speed of the plasma. This
  speed profile controls how steep the shock can grow and how stable
  the shock remains while propagating away from the Sun. Only a steep
  shock can provide for an effective particle acceleration.

---------------------------------------------------------
Title: Geoeffective Solar Activity: Coronal Mass Ejections, SEP
    Events and Geomagnetic Storms Over Solar Cycle 23
Authors: M P; Gopalswamy, N.; Yashiro, S.; Akiyama, S.; Xie, H.;
   Valtonen, E.
2008AGUSMSH43A..07M    Altcode:
  We present updated results for solar cycle 23 on coronal mass ejections
  (CMEs) and solar energetic particle (SEP) events and their correlations
  with solar sources and ensuing interplanetary disturbances and
  geomagnetic storms. The main data set consists of observations over
  the years 1996--2007 by the LASCO coronagraph and the ERNE particle
  detector, both on board the SOHO spacecraft. We study the properties
  of CMEs and the associated geomagnetic storms and the evolution of the
  properties during solar cycle 23. Especially we are interested with
  CMEs that are both geoeffective and SEPeffective. Special emphasis will
  be given to halo CMEs which are the most likely CMEs to be geoeffective.

---------------------------------------------------------
Title: Effects of solar wind dynamic pressure and preconditioning
    on large geomagnetic storms
Authors: Xie, H.; Gopalswamy, N.; Stcyr, C.; Yashiro, S.
2008AGUSMSM31C..02X    Altcode:
  We investigate the effects of solar wind dynamic pressure, Pdyn, and
  preconditioning in 88 large magnetic storms occurring during solar
  cycle 23. We have developed an improved model of the Dst profile,
  based on a modified Burton equation, where additional effects of
  Pdyn and diminished Dst pressure-correction have been taking into
  account. On the average, our model predicts the Dst peak values within
  9% of observations and gives an overall RMS error of 11%, which is an
  improvement over those models whose injection functions only depend on
  the solar wind electric field. The results demonstrate that there is
  an increase in the Dst peak value when there is a large enhancement
  of Pdyn during the main phase of a storm. The average increase of
  the storm intensity is estimated to be 26% for 15 storms with the max
  (Pdyn) &gt; 15 nPa. We find that the preconditioning in multi-step Dst
  storms plays no significant role in strengthening the storm intensity,
  but increases the storm duration.

---------------------------------------------------------
Title: Properties of Coronal Holes Associated With Large Geomagnetic
    Storms
Authors: Akiyama, S.; Gopalswamy, N.; Yashiro, S.
2008AGUSMSP51A..15A    Altcode:
  We study the characteristics of 11 equatorial coronal holes (CHs),
  which resulted in large (minimum Dst index &lt; - 100 nT) geomagnetic
  storms in the interval 1996 to 2005. These storms were part of the
  Living with a Star (LWS) Coordinated Data-Analysis Workshop (CDAW)
  held in March 2005. Using 17 GHz microwave images obtained by the
  Nobeyama Radio Heliograph (NoRH) and EUV images obtained by the
  Extreme-ultraviolet Imaging Telescope (EIT), we find the EUV CH area
  and the CH radio enhancement area are linearly correlated with the solar
  wind speed. The solar wind speed is also related to the flux expansion
  factor obtained as the ratio between areas of radio enhancement and EUV
  CH. We study the temporal sequences of the solar wind parameters and
  show that the time of CH central meridian passage, peak total magnetic
  field strength, peak temperature, and peak speed are delayed by -2.5,
  0.1, 0.6, 1.1 days from the time of peak CIR density, respectively.

---------------------------------------------------------
Title: Heating and Kinematics of an Eruptive Prominence Associated
    with a Fast Coronal Mass Ejection
Authors: Gopalswamy, N.; Yashiro, S.; Shibasaki, K.
2008AGUSMSH31C..07G    Altcode:
  The fast (1800 km/s) coronal mass ejection (CME) on 2005 July 27
  had a bright bubble-shaped prominence core observed by the Nobeyama
  Radioheliograph (NoRH) in microwaves (17 and 34 GHz), TRACE at 171 A,
  and the Extreme-ultraviolet Imaging Telescope (EIT) on board SOHO. NoRH
  has the largest field of view among the non- white light instruments,
  so the prominence could be tracked until it reached a height of about
  0.75 solar radii from the limb. The prominence remained optically thick
  at both 17 and GHz, even though it was significantly heated. Comparison
  with TRACE observations suggest that the prominence was heated in
  individual fibers within the prominence, making it multi-thermal
  plasma. The prominence maintained its overall shape as it entered into
  the field of view of SOHO/LASCO coronagraphs with a speed of about 1400
  km/s, so the height-time history could be studied over a distance of
  more than 20 solar radii from the Sun. NoRH data indicated that the
  initial acceleration was extremely high (about1.4 km/s/s). During the
  slow-rise phase of the prominence, EUV loops overlying the prominence
  also moved out, which when combines with CME leading-edge measurements
  from LASCO/C2 yielded an acceleration of about 300 m/s/s. This was
  comparable to the average acceleration of the prominence over the same
  height range. When we consider the just the LASCO field of view, both
  the prominence core and the CME leading edge showed deceleration, but to
  vastly different extents (-32 m/s/s for the CME leading edge compared to
  -3 m/s/s for the prominence core). Our preliminary conclusion is that
  the prominence was insulated from interacting with the non-CME ambient
  medium, which might explain the weaker slowing down of the prominence.

---------------------------------------------------------
Title: Poor CME Productivity in Active Region 10960
Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.
2008AGUSMSH31A..03Y    Altcode:
  Larger flares are generally likely to be associated with coronal mass
  ejections (CMEs), but there are some CME- poor active regions, which
  produce many large flares without associated CMEs. We present once such
  active region NOAA 10960, which produced 10 M-class flares during the
  disk passage. We examined their CME associations using coronagraph
  observations obtained by LASCO on SOHO and SECCHI on STEREO. The
  three coronagraph observations help us to determine whether or not
  a flare has the associated CME. We found that two out of 10 M-class
  flares were associated with the CMEs. The rate (20%) is low compared
  to the average CME association rate (50%) of M-class flares during the
  solar cycle 23. In addition, the associated CMEs are slow (337 km/s
  and 208 km/s); further strengthening the conclusion that AR 10960 is
  CME-poor. We consider various possibilities to explain why the active
  region is CME-poor.

---------------------------------------------------------
Title: Space Weather Application Using Projected Velocity Asymmetry
    of Halo CMEs
Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S.
2008SoPh..248..113M    Altcode: 2008arXiv0801.1977M; 2008SoPh..tmp...24M
  Halo coronal mass ejections (HCMEs) originating from regions close
  to the center of the Sun are likely to be responsible for severe
  geomagnetic storms. It is important to predict geoeffectiveness of HCMEs
  by using observations when they are still near the Sun. Unfortunately,
  coronagraphic observations do not provide true speeds of CMEs because
  of projection effects. In the present paper, we present a new technique
  to allow estimates of the space speed and approximate source location
  using projected speeds measured at different position angles for a
  given HCME (velocity asymmetry). We apply this technique to HCMEs
  observed during 2001 - 2002 and find that the improved speeds are
  better correlated with the travel times of HCMEs to Earth and with
  the magnitudes of ensuing geomagnetic storms.

---------------------------------------------------------
Title: Average Thickness of Magnetosheath Upstream of Magnetic Clouds
    at 1 AU versus Solar Longitude of Source
Authors: Lepping, R. P.; Wu, C. -C.; Gopalswamy, N.; Berdichevsky,
   D. B.
2008SoPh..248..125L    Altcode: 2008SoPh..tmp...35L
  Starting with a large number (N=100) of Wind magnetic clouds (MCs)
  and applying necessary restrictions, we find a proper set of N=29
  to investigate the average ecliptic plane projection of the upstream
  magnetosheath thickness as a function of the longitude of the solar
  source of the MCs, for those cases of MCs having upstream shock waves. A
  few of the obvious restrictions on the full set of MCs are the need for
  there to exist a driven upstream shock wave, knowledge of the MC's solar
  source, and restriction to only MCs of low axial latitudes. The analysis
  required splitting this set into two subsets according to average
  magnetosheath speed: slow/average (300 - 500 km s<SUP>−1</SUP>) and
  fast (500 - 1100 km s<SUP>−1</SUP>) speeds. Only the fast set gives
  plausible results, where the estimated magnetosheath thickness (ΔS)
  goes from 0.042 to 0.079 AU (at 1 AU) over the longitude sector of 0°
  (adjusted source-center longitude of the average magnetic cloud) to
  40° off center (East or West), based on N=11 appropriate cases. These
  estimates are well determined with a sigma (σ) for the fit of 0.0055
  AU, where σ is effectively the same as \sqrt{} (chi-squared) for the
  appropriate quadratic fit. The associated linear correlation coefficient
  for ΔS versus |Longitude| was very good (c.c.=0.93) for the fast
  range, and ΔS at 60° longitude is extrapolated to be 2.7 times the
  value at 0°. For the slower speeds we obtain the surprising result
  that ΔS is typically more-or-less constant at 0.040±0.013 AU at all
  longitudes, indicating that the MC as a driver, when moving close to
  the normal solar wind speed, has little influence on magnetosheath
  thickness. In some cases, the correct choice between two candidate
  solar-source longitudes for a fast MC might be made by noting the value
  of the observed ΔS just upstream of the MC. Also, we point out that,
  for the 29 events, the average sheath speed was well correlated with
  the quantity ΔV[=(«V<SUB>MC</SUB>»−«V<SUB>UPSTREAM</SUB>»)],
  and also with both «V<SUB>MC</SUB>» and «V<SUB>MC,T</SUB>», where
  «V<SUB>MC</SUB>» is the first one-hour average of the MC speed,
  «V<SUB>MC,T</SUB>» is the average MC speed across the full MC,
  and «V<SUB>UPSTREAM</SUB>» is a five-hour average of the solar wind
  speed just upstream of the shock.

---------------------------------------------------------
Title: Effects of solar wind dynamic pressure and preconditioning
    on large geomagnetic storms
Authors: Xie, H.; Gopalswamy, N.; St. Cyr, O. C.; Yashiro, S.
2008GeoRL..35.6S08X    Altcode:
  We investigate the effects of solar wind dynamic pressure, P <SUB>
  dyn </SUB>, and preconditioning in 88 large magnetic storms (Dst
  &lt; -100 nT) occurring during solar cycle 23. We have developed an
  improved model of the Dst profile, based on a modified Burton equation,
  where additional effects of P <SUB> dyn </SUB> and diminished Dst
  pressure-correction have been taking into account. On the average,
  our model predicts the Dst peak values within 9% of observations
  and gives an overall RMS error of 11%, which is an improvement over
  those models whose injection functions only depend on the solar wind
  electric field. The results demonstrate that there is an increase
  in the Dst peak value when there is a large enhancement of P <SUB>
  dyn </SUB> during the main phase of a storm. The average increase of
  the storm intensity is estimated to be 26% for 15 storms with the max
  (P <SUB> dyn </SUB>) &gt; 15 nPa. We find that the preconditioning in
  multi-step Dst storms plays no significant role in strengthening the
  storm intensity, but increases the storm duration.

---------------------------------------------------------
Title: Radio-Quiet Fast and Wide Coronal Mass Ejections
Authors: Gopalswamy, N.; Yashiro, S.; Xie, H.; Akiyama, S.;
   Aguilar-Rodriguez, E.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. -L.
2008ApJ...674..560G    Altcode:
  We report on the properties of radio-quiet (RQ) and radio-loud (RL)
  coronal mass ejections (CMEs) that are fast and wide (FW). RQ CMEs
  lack type II radio bursts in the metric and decameter-hectometric (DH)
  wavelengths. RL CMEs are associated with metric or DH type II bursts. We
  found that ~40% of the FW CMEs from 1996 to 2005 were RQ. The RQ CMEs
  had an average speed of 1117 km s<SUP>-1</SUP> compared to 1438 km
  s<SUP>-1</SUP> for the RL, bracketing the average speed of all FW CMEs
  (1303 km s<SUP>-1</SUP>). The fraction of full halo CMEs (apparent width
  = 360°) was the largest for the RL CMEs (60%), smallest for the RQ CMEs
  (16%), and intermediate for all FW CMEs (42%). The median soft X-ray
  flare size for the RQ CMEs (C6.9) was also smaller than that for the RL
  CMEs (M3.9). About 55% of RQ CMEs were back sided, while the front-sided
  ones originated close to the limb. The RL CMEs originated generally on
  the disk with only ~25% being back sided. The RQ FW CMEs suggest that
  the Alfvén speed in the low-latitude outer corona can often exceed
  1000 km s<SUP>-1</SUP> and can vary over a factor of &gt;=3. None of
  the RQ CMEs was associated with large solar energetic particle events,
  which is useful information for space weather applications.

---------------------------------------------------------
Title: Solar sources and geospace consequences of interplanetary
    magnetic clouds observed during solar cycle 23
Authors: Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.;
   Lepping, R. P.
2008JASTP..70..245G    Altcode:
  We present results of a statistical investigation of 99 magnetic
  clouds (MCs) observed during 1995-2005. The MC-associated coronal mass
  ejections (CMEs) are faster and wider on the average and originate
  within ±30o from the solar disk center. The solar sources of MCs also
  followed the butterfly diagram. The correlation between the magnetic
  field strength and speed of MCs was found to be valid over a much
  wider range of speeds. The number of south-north (SN) MCs was dominant
  and decreased with solar cycle, while the number of north-south (NS)
  MCs increased confirming the odd-cycle behavior. Two-thirds of MCs
  were geoeffective; the Dst index was highly correlated with speed
  and magnetic field in MCs as well as their product. Many (55%) fully
  northward (FN) MCs were geoeffective solely due to their sheaths. The
  non-geoeffective MCs were slower (average speed ), had a weaker
  southward magnetic field (average ), and occurred mostly during the
  rise phase of the solar activity cycle.

---------------------------------------------------------
Title: Spatial Relationship between Solar Flares and Coronal Mass
    Ejections
Authors: Yashiro, S.; Michalek, G.; Akiyama, S.; Gopalswamy, N.;
   Howard, R. A.
2008ApJ...673.1174Y    Altcode: 2007arXiv0710.3054Y
  We report on the spatial relationship between solar flares and coronal
  mass ejections (CMEs) observed during 1996-2005 inclusive. We identified
  496 flare-CME pairs considering limb flares (distance from central
  meridian &gt;=45°) with soft X-ray flare size &gt;=C3 level. The CMEs
  were detected by the Large Angle and Spectrometric Coronagraph (LASCO)
  on board the Solar and Heliospheric Observatory (SOHO). We investigated
  the flare positions with respect to the CME span for the events with
  X-class, M-class, and C-class flares separately. It is found that
  the most frequent flare site is at the center of the CME span for all
  the three classes, but that frequency is different for the different
  classes. Many X-class flares often lie at the center of the associated
  CME, while C-class flares widely spread to the outside of the CME
  span. The former is different from previous studies, which concluded
  that no preferred flare site exists. We compared our result with the
  previous studies and conclude that the long-term LASCO observation
  enabled us to obtain the detailed spatial relation between flares and
  CMEs. Our finding calls for a closer flare-CME relationship and supports
  eruption models typified by the CSHKP magnetic reconnection model.

---------------------------------------------------------
Title: Origin of Geoeffective Coronal Mass Ejections during Solar
    Cycle 23
Authors: Gopalswamy, Nat
2008cosp...37.1057G    Altcode: 2008cosp.meet.1057G
  The importance of coronal mass ejections (CMEs) in causing major
  geomagnetic storms has been well established in the 1990s due to the
  southward magnetic field contained in the sheath and ejecta portions
  of the interplanetary (IP) counterparts of CMEs (or ICMEs). The nice
  ordering of the internal structure of ICMEs revealed by in situ
  observations (shock followed by sheath and ejecta with or without
  flux rope structure) is far from clear at the Sun because the remote
  sensing technique reveals only the mass content of the CME rather
  than the magnetic properties. Nevertheless, there have been several
  attempts to relate the internal structure of CMEs to the magnetic
  properties of the source active regions on the Sun. For example,
  the filament marking the polarity inversion lines have been shown
  to be in the same direction as the axis of the flux rope observed
  in the IP medium. Such a correspondence is supported by the close
  relationship found between post eruption arcades at the Sun and the
  IP magnetic clouds (i.e., flux ropes). However, not all ICMEs or flux
  ropes, which may very well be an observational effect. The number of
  ICMEs with flux rope structure observed near Earth varies with the
  solar cycle and there are indications that the global magnetic field
  of the Sun and the active region field have varying contribution in
  deciding the magnetic properties of ICMEs. The sheath is most likely
  related to the global field of the Sun, while the ejecta is related
  to the active region magnetic field. The sheath is created by the
  ejecta portion as it compresses the overlying global field. We are
  still not in a position to resolve the sheath and ejecta portions
  of CMEs near the Sun, especially in those heading towards Earth and
  causing geomagnetic storms. Nevertheless, CME observations can help
  us infer the strength and orientation of the magnetic field in ICMEs,
  which are key parameters deciding the occurrence and strength of
  geomagnetic storms. This paper summarizes the current developments in
  the understanding of the CME-ICME relationship using the complete data
  sets on CMEs, ICMEs, and geomagnetic storms over one complete solar
  cycle that just ended in December 2007.

---------------------------------------------------------
Title: Width of Radio-Loud and Radio-Quiet CMEs
Authors: Michalek, G.; Gopalswamy, N.; Xie, H.
2007SoPh..246..409M    Altcode: 2007arXiv0710.4519M
  In the present paper we report on the difference in angular sizes
  between radio-loud and radio-quiet CMEs. For this purpose we compiled
  these two samples of events using Wind/WAVES and SOHO/LASCO observations
  obtained during 1996 - 2005. We show that the radio-loud CMEs are almost
  twice as wide as the radio-quiet CMEs (considering expanding parts of
  CMEs). Furthermore, we show that the radio-quiet CMEs have a narrow
  expanding bright part with a large extended diffusive structure. These
  results were obtained by measuring the CME widths in three different
  ways.

---------------------------------------------------------
Title: A Statistical Study of the Ejecta - Shock Standoff Distance
    of Geoeffective Events
Authors: Lara, A.; Gopalswamy, N.; Yashiro, S.; Borgazzi, A. I.
2007AGUFMSH31A0236L    Altcode:
  e study the interplanetary transport of 57 coronal mass ejections
  (CMEs), which are part of the events responsible for large geomagnetic
  storms of solar cycle 23 listed in the CDAW database. The interplanetary
  counterparts of these CMEs (ICMEs) were shock-driving and have caused
  intense (Dst &lt; -100) geomagnetic storms. We study the statistical
  behavior of the standoff distance and time between the ICME and
  the shock. We divided our events into two groups, 1) events where
  there is likely a one-to-one relationship between the CMEs and ICMEs
  (unique events) and 2) events where multiple CMEs may be associated
  with a single ICME. We find that the standoff time of the unique events
  follows a normal distribution whit a mean of 7.6 hr. and a sigma σ =
  4.7 hr. The standoff distance of unique events also follows a normal
  distribution with a mean of ~ 0.1 AU and a sigma of ~ 0.05 AU. We did
  not found any relationship between the position of the AR,associated
  to the low coronal CME activity, and the standoff distance. On the
  other hand there seems to be a linear relationship between the CME
  speed and the standoff distance.

---------------------------------------------------------
Title: Prediction of Space Weather Using an Asymmetric Cone Model
    for Halo CMEs
Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S.
2007SoPh..246..399M    Altcode: 2007arXiv0710.4372M
  Halo coronal mass ejections (HCMEs) are responsible of the most
  severe geomagnetic storms. A prediction of their geoeffectiveness
  and travel time to Earth's vicinity is crucial to forecast space
  weather. Unfortunately, coronagraphic observations are subjected
  to projection effects and do not provide true characteristics of
  CMEs. Recently, Michalek (Solar Phys.237, 101, 2006) developed an
  asymmetric cone model to obtain the space speed, width, and source
  location of HCMEs. We applied this technique to obtain the parameters
  of all front-sided HCMEs observed by the SOHO/LASCO experiment during
  a period from the beginning of 2001 until the end of 2002 (solar cycle
  23). These parameters were applied for space weather forecasting. Our
  study finds that the space speeds are strongly correlated with the
  travel times of HCMEs to Earth's vicinity and with the magnitudes
  related to geomagnetic disturbances.

---------------------------------------------------------
Title: Synoptic Solar Radio Burst Source Directions Derived by the
    Ulysses URAP Investigation
Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Hess, R. A.;
   Reiner, M. J.; Hoang, S.
2007AGUFMSH41A0308M    Altcode:
  The Unified Radio and Plasma (URAP) investigation is one of 10
  instruments on the Ulysses spacecraft. Ulysses, with its highly inclined
  orbit around the sun, provides URAP with a unique perspective on solar
  radio bursts, which are usually emitted at low heliolatitudes as the
  electron sources move outward from the sun. These radio bursts provide
  positional information relating to interplanetary coronal mass ejections
  (type II radio bursts), the initiation of CMEs (type III-L bursts), and
  solar flares (type III bursts). In this presentation, we use the routine
  radio direction-finding data from URAP to track radio bursts and locate
  their sources when Ulysses is near perihelion. Plots of these data are
  available on the URAP Goddard Space Flight Center web site (for example,
  http://urap.gsfc.nasa.gov/cgi/giffer?date=20070726&amp;PLOT_TYPE=
  DIRFIND), as are ASCII data files. The results shown are derived
  from fitting the spin-plane antenna data only; we compare the
  source directions so derived to the more accurate determinations
  made by fitting to both URAP antennas. The accuracy of the radio
  source directions to identify flare locations, determine solar wind
  densities remotely, etc., will be compared to previously published
  determinations. Applications to Wind Waves and STEREO Waves data,
  for which the spacecraft are in-ecliptic, will be addressed briefly.

---------------------------------------------------------
Title: A Catalog of Halo Coronal Mass Ejections from SOHO
Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Xie, H.; Vourlidas,
   A.; Howard, R. A.; Schmidt, J.
2007AGUFMSH51A0262G    Altcode:
  Halo coronal mass ejections (CMEs) have become one of the important
  subsets of CMEs, thanks to the extensive data accumulated by the Solar
  and Heliospheric Observatory (SOHO) mission. Halo CMEs are inherently
  more energetic on the average, so they are important for producing
  geomagnetic storms and solar energetic particle events (Gopalswamy et
  al., 2007). One of the key aspects halo CMEs is their source location,
  which decides whether the halo is symmetric or not. When the source
  is closer to the solar limb, the CMEs tend to become asymmetric halos
  or partial halos. Halos with their sources nearer to the limb are also
  the fastest (because of projection effects), but are less geoeffective
  due to the glancing blow they deliver to Earth's magnetosphere. Thus,
  providing source information to all halo CMEs in a separate catalog is
  useful information in selecting candidate geoeffective CMEs. The second
  important quantity of CMEs is the space speed, which decides the arrival
  time of CMEs at Earth. Since CMEs change their width during their early
  evolution, it is not easy to correct for the projection effects from the
  geometry of eruption. One way of correcting for projection effects is to
  use a cone model for CMEs. There are at least 3 published cone models,
  all of them seem to remove the projection effects reasonably well. The
  geometric parameters of the cone are determined using different methods
  in each model. Here we use the model by Xie et al. (2004), which has
  generally less restrictions, and hence can be applied to more number
  of halos. This paper provides a brief description of the catalog of
  halo CMEs, which resides at the CDAW Data Center, NASA Goddard Space
  Flight Center, Greenbelt, MD. The catalog enhances the existing data
  services at the CDAW Data Center, which participates in the Virtual
  Solar Observatory. Work supported by NASA's Virtual Observatories for
  Solar and Space Physics Data Program. References Gopalswamy et al.,
  JGR, 112, A06112, doi:10.1029/2006JA012149, 2007 Xie et al. JGR, 109,
  A03109, doi: 10.1029/2003JA010226, 2004

---------------------------------------------------------
Title: Synthetic Radio Maps of CMEs up to 24 Solar Radii Heliocentric
    Distance
Authors: Schmidt, J. M.; Gopalswamy, N.
2007AGUFMSH23B..01S    Altcode:
  We present numerical MagnetoHydroDynamic (MHD) simulations of coronal
  mass ejections (CMEs) and plasma simulations of radio emission from
  the CME-driven shocks. The simulations correspond to an idealized
  system, where rotational symmetry around the rotation axis of the Sun
  is assumed. So the CME has a flux rope structure that extends like a
  torus around the symmetry axis, i.e. no geometrical effects due to a
  connection of footpoints of the flux rope with the solar surface are
  considered. The CME-driven shock extends to an almost spherical shape
  during the temporal evolution of the CME. We find that our simulations
  can reproduce the dynamic spectra of coronal radio type II bursts, where
  the frequency drift rates correspond to the CME-driven shock speeds. We
  find further, that the CME-driven shock is an effective radio emitter at
  metric wavelengths, when the CME has reached a heliocentric distance of
  about two solar radii (R\odot). Towards the center of the CME, where the
  plasma emission frequency drops significantly due to an over expansion
  of the core of the CME, the emission is eclipsed for a fixed frequency
  radio receiver. We apply our simulation results to explain the radio
  images of type II bursts obtained by radio heliographs, in particular
  to the banana-shaped images of radio sources associated with fast
  CMEs. The shock at the rear part of the CME can become an effective
  radio emitter, where reconnection of magnetic field lines leads to
  enhanced gradients of magnetic fields. Yet, this emission is usually at
  lower frequencies than that at the shock front. We apply our kinetic
  and analytic model of plasma radiation further to MHD simulations of
  CMEs in 3D. The differences between the 3D and 2D cases are discussed.

---------------------------------------------------------
Title: Division II / Working Group International Collaboration in
    Space Weather
Authors: Webb, David F.; Gopalswamy, Nat; Liu, William; Sibeck,
   David G.; Schmieder, Brigitte; Wang, Jingxiu; Wang, Chi
2007IAUTB..26..107W    Altcode:
  The IAU Division II WG on International Collaboration in Space Weather
  has as its main goal to help coordinate the many activities related to
  space weather at an international level. The WG currently includes
  the international activities of the International Heliospheric
  Year (IHY), the International Living with a Star (ILWS) program,
  the CAWSES (Climate and Weather of the Sun-Earth System) Working
  Group on Sources of Geomagnetic Activity, and Space Weather Studies
  in China. The coordination of IHY activities within the IAU is led
  by Division II under this working group. The focus of this half-day
  meeting was on the activities of the IHY program. About 20 people
  were in attendance. The Chair of the WG, David F. Webb, gave a brief
  introduction noting that the meeting would have two parts: first, a
  session on IHY activities emphasizing IHY Regional coordination and,
  second, a general discussion of the other programs of the WG involving
  international Space Weather activities.

---------------------------------------------------------
Title: Correction to “Solar and interplanetary sources of major
    geomagnetic storms (Dst &lt;= -100 nT) during 1996-2005”
Authors: Zhang, J.; Richardson, I. G.; Webb, D. F.; Gopalswamy, N.;
   Huttunen, E.; Kasper, J.; Nitta, N. V.; Poomvises, W.; Thompson,
   B. J.; Wu, C. -C.; Yashiro, S.; Zhukov, A. N.
2007JGRA..11212103Z    Altcode:
  <A href="/journals/ja/ja0712/2007JA012891/">Abstract Available</A>
  from <A href="http://www.agu.org">http://www.agu.org</A>

---------------------------------------------------------
Title: Solar and interplanetary sources of major geomagnetic storms
    (Dst &lt;= -100 nT) during 1996-2005
Authors: Zhang, J.; Richardson, I. G.; Webb, D. F.; Gopalswamy, N.;
   Huttunen, E.; Kasper, J. C.; Nitta, N. V.; Poomvises, W.; Thompson,
   B. J.; Wu, C. -C.; Yashiro, S.; Zhukov, A. N.
2007JGRA..11210102Z    Altcode:
  We present the results of an investigation of the sequence of
  events from the Sun to the Earth that ultimately led to the 88 major
  geomagnetic storms (defined by minimum Dst ≤ -100 nT) that occurred
  during 1996-2005. The results are achieved through cooperative
  efforts that originated at the Living with a Star (LWS) Coordinated
  Data-Analysis Workshop (CDAW) held at George Mason University in
  March 2005. On the basis of careful examination of the complete array
  of solar and in situ solar wind observations, we have identified
  and characterized, for each major geomagnetic storm, the overall
  solar-interplanetary (solar-IP) source type, the time, velocity, and
  angular width of the source coronal mass ejection (CME), the type and
  heliographic location of the solar source region, the structure of the
  transient solar wind flow with the storm-driving component specified,
  the arrival time of shock/disturbance, and the start and ending times
  of the corresponding IP CME (ICME). The storm-driving component,
  which possesses a prolonged and enhanced southward magnetic field
  (B<SUB>s</SUB>), may be an ICME, the sheath of shocked plasma (SH)
  upstream of an ICME, a corotating interaction region (CIR), or a
  combination of these structures. We classify the Solar-IP sources
  into three broad types: (1) S-type, in which the storm is associated
  with a single ICME and a single CME at the Sun; (2) M-type, in which
  the storm is associated with a complex solar wind flow produced by
  multiple interacting ICMEs arising from multiple halo CMEs launched
  from the Sun in a short period; (3) C-type, in which the storm is
  associated with a CIR formed at the leading edge of a high-speed stream
  originating from a solar coronal hole (CH). For the 88 major storms,
  the S-type, M-type, and C-type events number 53 (60%), 24 (27%), and 11
  (13%), respectively. For the 85 events for which the surface source
  regions could be investigated, 54 (63%) of the storms originated in
  solar active regions, 11 (13%) in quiet Sun regions associated with
  quiescent filaments or filament channels, and 11 (13%) were associated
  with coronal holes. Remarkably, nine (11%) CME-driven events showed no
  sign of eruptive features on the surface or in the low corona (e.g.,
  no flare, no coronal dimming, and no loop arcade, etc.), even though
  all the available solar observations in a suitable time period were
  carefully examined. Thus while it is generally true that a major
  geomagnetic storm is more likely to be driven by a frontside fast
  halo CME associated with a major flare, our study indicates a broad
  distribution of source properties. The implications of the results
  for space weather forecasting are briefly discussed.

---------------------------------------------------------
Title: Energetic Phenomena on the Sun
Authors: Gopalswamy, Nat
2007AIPC..919..275G    Altcode:
  Solar flares, coronal mass ejections (CMEs), solar energetic particles
  (SEPs), and fast solar wind represent the energetic phenomena on the
  Sun. Flares and CMEs originate from closed magnetic field structures
  on the Sun typically found in active regions and quiescent filament
  regions. On the other hand, fast solar wind originates from open field
  regions on the Sun, identified as coronal holes. Energetic particles
  are associated with flares, CMEs, and fast solar wind, but the ones
  associated with CMEs are the most intense. The energetic phenomena have
  important consequences in the heliosphere and contribute significantly
  to adverse space weather. This paper provides an over view of the
  energetic phenomena on the Sun including their origin interplanetary
  propagation and space weather consequences.

---------------------------------------------------------
Title: The Early Life Of A Coronal Mass Ejection From SECCHI And
    SOHO Observations
Authors: Gopalswamy, N.; Yashiro, S.; Davila, J. M.; Howard, R. A.;
   SECCHI/COR1 Team
2007AAS...210.2813G    Altcode: 2007BAAS...39..324G
  One of the key advantages of STEREO/SECCHI is the inner coronagraph
  (COR1), which can observe CMEs in the coronal region where CMEs
  attain their maximum acceleration. The first CME observed by COR1
  was on 2006 December 30. The CME was also observed by the C2 and C3
  coronagraphs of SOHO. We compare the morphological and height-time
  histories between COR1 and SOHO/LASCO data. We find that the flux
  rope structure evolves significantly between the COR1 and LASCO/C2
  FOVs, although we can track features to get a continuous height-time
  history of the CME. We find excellent agreement between the two sets
  of data which could be combined to obtain the kinematic properties
  of the CME. We also superposed a STEREO/COR1 image of the CME on a
  STEREO/EUVI image and SOHO/C2 image to compare the solar origin and
  morphology. The CME originated from the southwest quadrant of the Sun
  and was of flux-rope type moving with an average speed of 200 km/s and
  an acceleration of 6 m/s/s, with a characteristic two-ribbon structure
  and an extended post-eruption arcade. In addition to the similarity in
  CME features, there was excellent correspondence between the outlying
  streamers in the two coronagraph images.

---------------------------------------------------------
Title: Geoeffectiveness of halo coronal mass ejections
Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.
2007JGRA..112.6112G    Altcode: 2007JGRA..11206112G
  We studied the geoeffectiveness, speed, solar source, and flare
  association of a set of 378 halo coronal mass ejections (CMEs) of cycle
  23 (1996-2005, inclusive). We compiled the minimum Dst values occurring
  within 1-5 days after the CME onset. We compared the distributions of
  such Dst values for the following subsets of halo CMEs: disk halos
  (within 45 deg from disk center), limb halos (beyond 45 degrees but
  within 90 deg from disk center), and backside halo CMEs. Defining that a
  halo CME is geoeffective if it is followed by Dst ≤ -50 nT, moderately
  geoeffective if -50 nT &lt; Dst &lt; -100 nT, and strongly geoeffective
  if Dst ≤ -100 nT, we find that the disk halos are followed by strong
  storms, limb halos are followed by moderate storms, and backside halos
  are not followed by significant storms. The Dst distribution for a
  random sample is nearly identical to the case of backside halos. About
  71% of all frontside halos are geoeffective, supporting the high rate
  of geoeffectiveness of halo CMEs. A larger fraction (75%) of disk halos
  are geoeffective. Intense storms are generally due to disk halos and
  the few intense storms from limb halos occur only in the maximum and
  declining phases. Most intense storms occur when there are successive
  CMEs. The delay time between CME onset and minimum Dst value is the
  smallest for limb halos, suggesting that the sheath is geoeffective
  in these cases. The geoeffectiveness rate has prominent dips in 1999
  and 2002 (the beginning and end years of the solar maximum phase). The
  numbers of all frontside and geoeffective frontside halos show a triple
  peak structure similar to the number of intense geomagnetic storms. The
  difference in flare sizes among geoeffective and nongeoeffective halos
  is not significant. The nongeoeffective CMEs are generally slower
  and have more easterly or limbward solar sources compared to the
  geoeffective ones; source location and speed are the most important
  parameters for geoeffectiveness.

---------------------------------------------------------
Title: Why Some Fast and Wide Coronal Mass Ejections are Radio-quiet?
Authors: Gopalswamy, N.; Xie, H.; Aguilar-Rodriguez, E.; Akiyama,
   S.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J. L.
2007AAS...210.5801G    Altcode: 2007BAAS...39..167G
  The radio-quiet CMEs lack type II radio burst association in the
  metric and decameter-hectometric (DH) wavelengths. We compiled CMEs
  faster than 900 km/s and wider than 60 degrees and checked against
  metric and interplanetary type II bursts and found that about
  one third of them were radio-quiet. We compared the radio-quiet
  CMEs with the radio-loud ones occurring over the same study period
  (1996-2005). The radio-quiet and radio-loud CMEs had average speeds
  of 1129 and 1524 km/s, respectively bracketing the average speed of
  all FW CMEs (1303 km/s). The width distributions also showed a similar
  behavior: the fraction of halo and partial halo CMEs was the largest
  for the radio-loud CMEs (54%), smallest for the radio-quiet CMEs
  (18%) and intermediate for all fast and wide CMEs (42%). The majority
  of radio-quiet CMEs (55%) were back-sided; most of the frontsided
  ones also originated close to the limb. This is in contrast to the
  radio-loud CMEs which originated generally on the disk with only
  a small fraction (13%) was back-sided. The average flare size was
  also slightly smaller for the radio-quiet CMEs compared to that of
  radio-loud CMEs. Back-sided and limb CMEs have only part of the shock
  surface visible to the observer. This seems to be an important factor
  deciding whether a CME is radio quiet.

---------------------------------------------------------
Title: IHY - An International Cooperative Program
Authors: Rabello-Soares, M. Cristina; Davila, J.; Gopalswamy, N.;
   Thompson, B.
2007AAS...210.5701R    Altcode: 2007BAAS...39..167R
  The International Heliophysical Year (IHY) in 2007/2008 involves
  thousands of scientists representing over 70 nations. It consists
  of four distinct elements that will be described here. <P />Taking
  advantage of the large amount of heliophysical data acquired routinely
  by a vast number of sophisticated instruments aboard space missions and
  at ground-based observatories, IHY aims to develop the basic science of
  heliophysics through cross-disciplinary studies of universal processes
  by means of Coordinated Investigation Programs (CIPs). <P />The second
  component is in collaboration with the United Nations Basic Space
  Science Initiative (UNBSSI) and consists of the deployment of arrays of
  small, inexpensive instruments such as magnetometers, radio antennas,
  GPS receivers, etc. around the world to provide global measurements. An
  important aspect of this partnership is to foster the participation
  of developing nations in heliophysics research. <P />IHY coincides
  with the commemoration of 50 years of the space age that started with
  launch of Sputnik on October 4, 1957 and it is on the brink of a new
  age of space exploration where the Moon, Mars and the outer planets
  will be the focus of the space programs in the next years. As a result,
  it presents an excellent opportunity to create interest for science
  among young people with the excitement of discovery of space. The
  education and outreach program forms another cornerstone of IHY. <P
  />Last but not least, an important part of the IHY activities, its
  forth component, is to preserve the history and memory of IGY 1957.

---------------------------------------------------------
Title: Commission 10: Solar Activity
Authors: Melrose, Donald B.; Klimchuk, James A.; Benz, A. O.; Craig,
   I. J. D.; Gopalswamy, N.; Harrison, R. A.; Kozlovsky, B. Z.; Poletto,
   G.; Schrijver, K. J.; van Driel-Gesztelyi, L.; Wang, J. -X.
2007IAUTA..26...75M    Altcode:
  Commission 10 aims at the study of various forms of solar activity,
  including networks, plages, pores, spots, fibrils, surges, jets,
  filaments/prominences, coronal loops, flares, coronal mass ejections
  (CMEs), solar cycle, microflares, nanoflares, coronal heating etc.,
  which are all manifestation of the interplay of magnetic fields and
  solar plasma. Increasingly important is the study of solar activities
  as sources of various disturbances in the interplanetary space
  and near-Earth "space weather".Over the past three years a major
  component of research on the active Sun has involved data from the
  RHESSI spacecraft. This review starts with an update on current and
  planned solar observations from spacecraft. The discussion of solar
  flares gives emphasis to new results from RHESSI, along with updates on
  other aspects of flares. Recent progress on two theoretical concepts,
  magnetic reconnection and magnetic helicity is then summarized, followed
  by discussions of coronal loops and heating, the magnetic carpet
  and filaments. The final topic discussed is coronal mass ejections
  and space weather.The discussions on each topic is relatively brief,
  and intended as an outline to put the extensive list of references
  in context.The review was prepared jointly by the members of the
  Organizing Committee, and the names of the primary contributors to
  the various sections are indicated in parentheses.

---------------------------------------------------------
Title: Properties of Interplanetary Coronal Mass Ejections
Authors: Gopalswamy, Nat
2007sdeh.book..145G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: International Heliophysical Year 2007: Basic space science
    initiatives
Authors: Davila, Joe; Gopalswamy, Nat; Haubold, Hans J.; Thompson,
   Barbara
2007SpPol..23..121D    Altcode:
  The UN Office for Outer Space Affairs, through the IHY Secretariat
  and the United Nations Basic Space Science Initiative (UNBSSI),
  assists scientists and engineers world-wide to participate in
  the International Heliophysical Year (IHY) 2007. A major thrust of
  IHY/UNBSSI is to deploy arrays of small, inexpensive instruments such
  as magnetometers, radio telescopes, GPS receivers, all-sky cameras,
  etc. around the world to allow global measurements of ionospheric and
  heliospheric phenomena. The small instrument program is envisioned
  as a partnership between instrument providers and instrument hosts
  in developing nations, with the former providing the instruments,
  the host nation the manpower, facilities and operational support,
  typically at a local university. Funds are not available through
  IHY/UNBSSI to build the instruments; these must be obtained through the
  normal proposal channels. All instrument operational support for local
  scientists, facilities, data acquisition, etc. will be provided by the
  host nation. The IHY/UNBSSI can facilitate the deployment of several
  of these networks and existing databases and relevant software tools
  will be identified to promote space science activities in developing
  nations. Extensive data on space science have been accumulated
  by a number of space missions. Similarly, long-term databases are
  available from ground-based observations. These data can be utilized
  in ways different from those originally intended for understanding the
  heliophysical processes. This report provides an overview of IHY/UNBSSI,
  its achievements, future plans and outreach to the 192 member states
  of the United Nations.

---------------------------------------------------------
Title: The United Nations Basic Space Science Initiative for IHY 2007
Authors: Gopalswamy, Nat; Davila, Joseph; Thompson, Barbara; Haubold,
   Hans
2007IAUSS...5..295G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Scientific Justification For The Low- Frequency Radio
    Measurements By The Solar Orbiter Mission
Authors: Gopalswamy, N.; MacDowall, R. J.; Kaiser, M. L.; Bale, S. D.;
   Maksimovic, M.; Bougeret, J. -L.
2007ESASP.641E..66G    Altcode:
  The importance of the radio measurements in the frequency range 1-14
  MHz has been demonstrated only recently by the Radio and Plasma Wave
  (WAVES) Experiment on board Wind. The shock-related radio emission
  below 14 MHz originates from a heliocentric distance beyond 2 solar
  radii in association with coronal mass ejections. Although several
  issues on the origin of shocks and their connection to solar eruptions
  have been clarified by the SOHO-Wind synergistic observations, some
  of them remain mainly because of lack of radio imaging and/or in situ
  observations at the shock source. The Solar Orbiter mission will be able
  to address these issues by directly sampling the shock at a location
  where the radio emission originates to provide measurements of physical
  parameters for direct comparison with theory and modelling. We highlight
  some of the science issues that can be addressed by a radio and plasma
  wave analyzer on board the Solar Orbiter mission in combination with
  in situ measurements close to the Sun.

---------------------------------------------------------
Title: The United Nations Basic Space Science Initiative: the
    TRIPOD concept
Authors: Kitamura, Masatoshi; Wentzel, Don; Henden, Arne; Bennett,
   Jeffrey; Al-Naimiy, H. M. K.; Mathai, A. M.; Gopalswamy, Nat; Davila,
   Joseph; Thompson, Barbara; Webb, David; Haubold, Hans
2007IAUSS...5..277K    Altcode: 2006physics..10149K
  Since 1990, the United Nations is annually holding a workshop on
  basic space science for the benefit of the worldwide development of
  astronomy. Additional to the scientific benefits of the workshops and
  the strengthening of international cooperation, the workshops lead to
  the establishment of astronomical telescope facilities through the
  Official Development Assistance (ODA) of Japan. Teaching material,
  hands-on astrophysics material, and variable star observing programmes
  had been developed for the operation of such astronomical telescope
  facilities in an university environment. This approach to astronomical
  telescope facility, observing programme, and teaching astronomy has
  become known as the basic space science TRIPOD concept. Currently,
  a similar TRIPOD concept is being developed for the International
  Heliophysical Year 2007, consisting of an instrument array, data taking
  and analysis, and teaching space science.

---------------------------------------------------------
Title: The CME-productivity associated with flares from two active
    regions
Authors: Akiyama, S.; Yashiro, S.; Gopalswamy, N.
2007AdSpR..39.1467A    Altcode:
  We report on two flare-productive adjacent active regions (ARs),
  with different levels of coronal mass ejection (CME) association. AR
  10039 and AR 10044 produced strong X-ray flares during their disk
  passages. We examined the CME association rate of X-ray flares and
  found it to be different between the two ARs. AR 10039 was CME-rich
  with 72% association with flares, while AR 10044 was CME-poor with an
  association rate of only 14%. CMEs from the CME-rich AR were faster
  and wider than the ones from the CME-poor AR. The flare activity of AR
  10044 was temporally concentrated over a short interval and spatially
  localized over a compact area between the major sun spots. We suggest
  that different pre-eruption evolution and magnetic configuration in
  the two regions might have contributed to the difference between the
  two ARs.

---------------------------------------------------------
Title: Energetic Particles Related with Coronal and Interplanetary
    Shocks
Authors: Gopalswamy, N.
2007LNP...725..139G    Altcode:
  Acceleration of electrons and ions at the Sun is discussed in the
  framework of CME-driven shocks. Based on the properties of coronal
  mass ejections associated with type II bursts at various wavelengths,
  the possibility of a unified approach to the type II phenomena is
  suggested. Two aspects of primary importance to shock accelerations are:
  (1) Energy of the driving CME and (2) the conditions in the medium
  that supports shock propagation. The high degree of overlap between
  CMEs associated with large solar energetic particle events and type II
  bursts occurring at all wavelengths underscores the importance of CME
  energy in driving shocks far into the interplanetary medium. Presence
  of preceding CMEs can alter the conditions in the ambient medium, which
  is shown to influence the intensity of large solar energetic particle
  events. Both statistical evidence and case studies are presented that
  underscore the importance of the ambient medium.

---------------------------------------------------------
Title: The International Heliophysical Year
Authors: Davila, Joseph M.; Gopalswamy, Nat; Thompson, Barbara J.
2007RoAJ...17....3D    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Radio Observatory for Lunar Sortie Science (ROLSS)
Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Demaio,
   L. D.; Lazio, J.; Weiler, K. W.; Bale, S. D.; Burns, J. O.; Jones,
   D. L.; Kasper, J. C.; Reiner, M. J.
2006AGUFMSM43A1476M    Altcode:
  It is widely recognized that the lunar surface is an ideal
  base for radio astronomy observations at frequencies below the
  terrestrial ionospheric cutoff frequency. The ionospheric cutoff
  (10-20 MHz) prevents observations of very low frequency radio
  sources outside the ionosphere from being conducted by ground-based
  observatories. Spacecraft or lunar-based observatories are the only
  alternative, with the lunar surface providing the real estate for
  establishing radio arrays with large dimensions (tens of kilometers)
  to perform high resolution imaging at the lowest frequencies (&lt; 10
  MHz). In this presentation, we describe a concept study for a pathfinder
  radio observatory to be deployed during a lunar sortie. The concept
  study focuses on appropriate antenna, receiver, deployment, power,
  and communication systems for the observatory. These systems must be
  low mass to permit the lunar sortie package to maximize science and
  engineering goals. Power requirements for the receiver systems and
  the downlink to Earth must also be minimized. The concept study also
  addresses in detail the science goals of this observatory, which include
  observations of solar radio bursts as proxies of solar and heliospheric
  particle acceleration, detailed measurement of the lunar ionosphere
  scale height as a function of time, integrated spectra of strong
  (extragalactic) sources to probe particle acceleration processes,
  and a survey of natural and man-made emissions from the Earth. These
  observations will enhance our understanding of the various radio
  sources and the lunar observing environment and pave the way for future
  larger-scale lunar radio astronomy arrays.

---------------------------------------------------------
Title: Investigating the state of the Sun-Earth system during extreme
events: First science results of a worldwide online conference series
Authors: Kozyra, J. U.; Shibata, K.; Fox, N. J.; Basu, S.; Coster,
   A. J.; Davila, J. M.; Gopalswamy, N.; Liou, K.; Lu, G.; Mann, I. R.;
   Pallamraju, D.; Paxton, L. J.; Peterson, W. K.; Talaat, E. R.;
   Weatherwax, A. T.; Young, C. A.; Zanetti, L. J.
2006AGUFMSA43A..01K    Altcode:
  This presentation reports on new science results from an online
  conference entitled "Return to the Auroral Oval for the Anniversary
  of the IGY" designed to bring together researchers worldwide: (1)
  to investigate newly reported features in the auroral oval during
  substorms that occur in the main phase of superstorms and how these
  features map throughout geospace, (2) to explore implications for the
  state of the geospace system, (3) to identify signatures associated
  with this geospace state from equatorial to polar latitudes,
  (4) to investigate the unusual aspects of the solar sources, and
  (5) to understand how propagation from Sun to Earth modified the
  observed solar drivers. The main focus of the first conference is on
  worldwide data exchange, the construction of global data products and
  assimilative global views, and identifying coupled chains of events
  from sun-to-Earth. The collaborative conference data products and
  enhanced understanding of the observed features of the events will
  form the basis for a follow-on conference in 2007 focused primarily
  on theoretical studies and collaborative simulation efforts between
  modeling groups, observers and data analysts. This conference is the
  first in a series of sun-Earth connection online conferences, sponsored
  by CAWSES, IHY, eGY, ICESTAR, NASA/LWS, and NSF Atmospheric Science
  Programs, and designed to bring interdisciplinary researchers together
  with the vast developing cyber-infrastructure of large international
  data sets, high performance computing and advanced visualizations to
  address grand challenge science issues in a way not previously possible.

---------------------------------------------------------
Title: Relationships Among Magnetic Clouds, CMES, and Geomagnetic
    Storms
Authors: Wu, C. C.; Lepping, R. P.; Gopalswamy, N.
2006SoPh..239..449W    Altcode: 2006SoPh..tmp...93W
  During solar cycle 23, 82 interplanetary magnetic clouds (MCs) were
  identified by the Magnetic Field Investigation (MFI) team using Wind
  (1995 - 2003) solar wind plasma and magnetic field data from solar
  minimum through the maximum of cycle 23. The average occurrence rate is
  9.5 MCs per year for the overall period. It is found that some of the
  anomalies in the frequency of occurrence were during the early part
  of solar cycle 23: (i) only four MCs were observed in 1999, and (ii)
  an unusually large number of MCs (17 events) were observed in 1997,
  just after solar minimum. We also discuss the relationship between
  MCs, coronal mass ejections (CMEs), and geomagnetic storms. During the
  period 1996 - 2003, almost 8000 CMEs were observed by SOHO-LASCO. The
  occurrence frequency of MCs appears to be related neither to the
  occurrence of CMEs as observed by SOHO LASCO nor to the sunspot
  number. When we included "magnetic cloud-like structures" (MCLs,
  defined by Lepping, Wu, and Berdichevsky, 2005), we found that the
  occurrence of the joint set (MCs + MCLs) is correlated with both
  sunspot number and the occurrence rate of CMEs. The average duration
  of the MCL structures is ~40% shorter than that of the MCs. The MCs
  are typically more geoeffective than the MCLs, because the average
  southward field component is generally stronger and longer lasting in
  MCs than in MCLs. In addition, most severe storms caused by MCs/MCLs
  with Dst<SUB>min</SUB>≤ −100 nT occurred in the active solar period.

---------------------------------------------------------
Title: Consequences of Coronal Mass Ejections in the Heliosphere
Authors: Gopalswamy, N.
2006SunGe...1b...5G    Altcode: 2006SunGe...1....5G
  Coronal mass ejections (CMEs) are the most energetic events in the
  heliosphere. They carry large amounts of coronal magnetic fields and
  plasma with them and drive large-scale interplanetary shocks. The CMEs
  and shock have significant consequences at various locations in the
  heliosphere, including the production of intense geomagnetic storms and
  large energetic particle events. CMEs form merged interaction regions
  in the heliosphere, which act as magnetic barriers for the galactic
  cosmic rays entering the heliosphere. After a brief summary of the
  observed properties of CMEs at the Sun, I discuss the properties
  of the interplanetary CMEs (ICMEs) and their connection to shocks,
  radio bursts, solar energetic particles and the modulation of galactic
  cosmic rays.

---------------------------------------------------------
Title: Radio Observations of Solar Eruptions
Authors: Gopalswamy, N.
2006spnr.conf...81G    Altcode:
  Coronal mass ejections (CMEs) are composed of multithermal plasmas,
  which make them produce different radio signatures at different
  wavelengths. The prominence core of CMEs are of the lowest temperature
  and hence optically thick at microwave frequencies and hence are
  readily observed. The Nobeyama Radioheliograph has exploited this fact
  and observed a large number of prominence eruptions over most of solar
  cycle 23 and parts of cycle 22. This paper reviews recent studies on
  prominence eruptions and their contributions for understanding the
  CME phenomenon. In particular, the following issues are discussed:
  (i) the statistical and physical relationship between CMEs and the
  radio prominence eruptions, and how this relationship manifests as a
  function of the solar cycle; (ii) The asymmetry of prominence eruptions
  between northern and southern hemispheres; (iii) the relationship
  between prominence eruptions and CME cores; (iv) the implications of
  the cessation of high-latitude PEs before the reversal of the global
  solar magnetic field, and (v) the implications of the high-latitude
  PEs and CMEs for the modulation of galactic cosmic rays. Finally,
  the importance of the Nobeyama Radioheliograph data to future missions
  such as STEREO and Solar-B are discussed.

---------------------------------------------------------
Title: General Discussion on Donor Programs
Authors: Gopalswamy, N.
2006ihy..workE..88G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Coronal Mass Ejections in the Heliosphere
Authors: Gopalswamy, N.
2006ihy..workE..46G    Altcode:
  Coronal mass ejections (CMEs) are the most energetic events in the
  heliosphere. They carry large amounts of coronal magnetic fields and
  plasma with them and driving large-scale interplanetary shocks. The
  CMEs and shock have significant consequences at various locations in the
  heliosphere, including the production of intense geomagnetic storms and
  large energetic particle events. CMEs form merged interaction regions
  in the heliosphere, which act as magnetic barriers for the galactic
  cosmic rays entering the heliosphere. After a brief summary of the
  observed properties of CMEs at the Sun, I discuss the properties
  of the interplanetary CMEs (ICMEs) and their connection to shocks,
  radio bursts, solar energetic particles and modulation of galactic
  cosmic rays.

---------------------------------------------------------
Title: General Discussion on Donor Programs N. Gopalswamy
Authors: Gopalswamy, N.
2006ihy..workE..86G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: IHY-CAWSES Data base
Authors: Young, C. A.; Thompson, B. J.; Davila, J.; Gopalswamy, N.
2006ihy..workE..90Y    Altcode:
  In partnership with the CAWSES (Climate And Weather of the Sun-Earth
  System) program, IHY is sponsoring a series of Virtual Workshops
  and a special IHY/CAWSES database to provide virtual access of data
  collected for IHY and CAWSES campaigns. The first of the virtual
  workshops occurred November 13-17, 2006, and had more than 200 online
  participants. Online presentation and discussion tools are being
  refined for future workshops. The IHY/CAWSES database provides a means
  of entering data into the Virtual Solar Observatory (to provide the
  maximum and easiest possible access to the data) while still maintaining
  a close connection to the other data sets used in IHY/CAWSES activities.

---------------------------------------------------------
Title: General Discussion on Donor Programs
Authors: Gopalswamy, N.
2006ihy..workE..87G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: IHY/UNBSS Program: Success Stories
Authors: Gopalswamy, N.; Davila, J.; Thompson, B. J.; Haubold, H. J.
2006ihy..workE..15G    Altcode:
  The United Nations Office for Outer Space Affairs, through the IHY
  secretariat and the United Nations Basic Space Science Initiative
  (UNBSSI) is assisting scientists and engineers from all over the world
  in participating in the International Heliophysical Year (IHY) 2007. A
  major thrust of the IHY/UNBSSI program is to deploy arrays of small,
  inexpensive instruments such as magnetometers, radio telescopes, GPS
  receivers, etc. around the world to provide global measurements of
  ionospheric and heliospheric phenomena. The small instrument program
  is a partnership between instrument providers, and instrument hosts in
  developing countries. The lead scientist will provide the instruments
  (or fabrication plans for instruments) in the array; the host country
  will provide manpower, facilities, and operational support to obtain
  data with the instrument typically at a local university. Existing data
  bases and relevant software tools can be identified to promote space
  science activities in developing countries. Extensive data on space
  science have been accumulated by a number of space missions. Similarly,
  long-term data bases are available from ground based observations. These
  data can be utilized in ways different from originally intended for
  understanding the heliophysical processes. This paper provides an
  overview of the IHY/UNBSS program, its achievements and future plans.

---------------------------------------------------------
Title: Improved input to the empirical coronal mass ejection (CME)
    driven shock arrival model from CME cone models
Authors: Xie, H.; Gopalswamy, N.; Ofman, L.; St. Cyr, O. C.; Michalek,
   G.; Lara, A.; Yashiro, S.
2006SpWea...410002X    Altcode:
  We study the Sun-Earth travel time of interplanetary shocks driven
  by coronal mass ejections (CMEs) using empirical cone models. Three
  different cone models have been used to obtain the radial speeds of
  the CMEs, which are then used as input to the empirical shock arrival
  (ESA) model to obtain the Sun to Earth travel time of the shocks. We
  compare the predicted and observed shock transit times and find that
  the accuracy of the ESA model is improved by applying CME radial speeds
  from the cone models. There are two ways of calculating the shock travel
  time: using the ESA model or using the simplified ESA formula obtained
  by an exponential fit to the ESA model. The average mean error in the
  travel time with the cone model speeds is 7.8 hours compared to 14.6
  hours with the sky plane speed, which amounts to an improvement of
  46%. With the ESA formula, the corresponding mean errors are 9.5 and
  11.7 hours, respectively, representing an improvement of 19%. The cone
  models minimize projection effects and hence can be used to obtain
  CME radial speeds. When input to the ESA model, the large scatter in
  the shock travel time is reduced, thus improving CME-related space
  weather predictions.

---------------------------------------------------------
Title: Solar Eruptions and Energetic Particles: An Introduction
Authors: Gopalswamy, N.; Mewaldt, R.; Torsti, J.
2006GMS...165....1G    Altcode:
  This introductory article highlights current issues concerning
  two related phenomena involving mass emission from the Sun: solar
  eruptions and solar energetic particles. A brief outline of the
  chapters is provided indicating how the current issues are addressed
  in the monograph. The sections in this introduction roughly group the
  chapters dealing with coronal mass ejections (CMEs), solar energetic
  particles (SEPs), shocks, and space weather. The concluding remarks
  include a brief summary of outstanding issues that drive current and
  future research on CMEs and SEPs.

---------------------------------------------------------
Title: Coronal Mass Ejections and Type II Radio Bursts
Authors: Gopalswamy, Nat
2006GMS...165..207G    Altcode:
  The simultaneous availability of white light data on CMEs from the Solar
  and Heliospheric Observatory (SOHO) and radio data on shock waves from
  the Radio and Plasma Wave experiment on board the Wind spacecraft over
  the past decade have helped in making rapid progress in understanding
  the CME-driven shocks. I review some recent developments in the type
  II-CME relationship, focusing on the properties of CMEs as shock drivers
  and those of the medium supporting shock propagation. I also discuss
  the solar cycle variation of the type II bursts in comparison with other
  eruptive phenomena such as CMEs, flares, large solar energetic particle
  events, and shocks detected in situ. The hierarchical relationship found
  between the CME kinetic energy and wavelength range of type II radio
  bursts, non-existence of CMEless type II bursts, and the explanation
  of type II burst properties in terms of shock propagation with a
  realistic profile of the fast mode speed suggest that the underlying
  shocks are driven by CMEs, irrespective of the wavelength domain. Such
  a unified approach provides an elegant understanding of the entire type
  II phenomenon (coronal and interplanetary). The blast wave scenario
  remains an alternative hypothesis for type II bursts only over a small
  spatial domain (within one solar radius above the solar surface) that
  is not accessible to in situ observation. Therefore the existence of
  blast waves cannot be directly confirmed. CMEs, on the other hand,
  can be remote sensed from this domain.

---------------------------------------------------------
Title: Different Power-Law Indices in the Frequency Distributions
    of Flares with and without Coronal Mass Ejections
Authors: Yashiro, S.; Akiyama, S.; Gopalswamy, N.; Howard, R. A.
2006ApJ...650L.143Y    Altcode: 2006astro.ph..9197Y
  We investigated the frequency distributions of flares with and without
  coronal mass ejections (CMEs) as a function of flare parameters (peak
  flux, fluence, and duration of soft X-ray flares). We used CMEs observed
  by the Large Angle and Spectrometric Coronagraph (LASCO) on board the
  Solar and Heliospheric Observatory (SOHO) mission and soft X-ray flares
  (C3.2 and above) observed by the Geostationary Operational Environmental
  Satellite (GOES) during 1996-2005. We found that the distributions
  obey a power law of the form dN/dX~X<SUP>-α</SUP>, where X is a
  flare parameter and dN is the number of events recorded within the
  interval [X, X+dX]. For the flares with (without) CMEs, we obtained
  the power-law index α=1.98+/-0.05 (α=2.52+/-0.03) for the peak flux,
  α=1.79+/-0.05 (α=2.47+/-0.11) for the fluence, and α=2.49+/-0.11
  (α=3.22+/-0.15) for the duration. The power-law indices for flares
  without CMEs are steeper than those for flares with CMEs. The larger
  power-law index for flares without CMEs supports the possibility that
  nanoflares contribute to coronal heating.

---------------------------------------------------------
Title: Properties and geoeffectiveness of halo coronal mass ejections
Authors: Michalek, G.; Gopalswamy, N.; Lara, A.; Yashiro, S.
2006SpWea...410003M    Altcode: 2007arXiv0710.4526M
  Halo coronal mass ejections (HCMEs) originating from regions close to
  the center of the Sun are likely to be geoeffective. Assuming that the
  shape of HCMEs is a cone and that the HCMEs propagate with constant
  angular widths and velocities, at least in their early phase, we have
  developed a technique which allowed us to obtain the space speed, width,
  and source location. We apply this technique to obtain the parameters
  of all full HCMEs observed by the Solar and Heliospheric Observatory
  (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO)
  experiment until the end of 2002. Using this data, we examine which
  parameters determine the geoeffectiveness of HCMEs. We show that in the
  considered period of time, only fast halo CMEs (with space velocities
  higher than ~1000 km/s) and originating from the Western Hemisphere
  close to the solar center could cause intense geomagnetic storms. We
  illustrate how the HCME parameters can be used for space weather
  forecast. It is also demonstrated that the strength of a geomagnetic
  storm does not depend on the determined width of HCMEs. This means that
  HCMEs do not have to be very large to cause major geomagnetic storms.

---------------------------------------------------------
Title: Coronal Mass Ejections of Solar Cycle 23
Authors: Gopalswamy, Nat
2006JApA...27..243G    Altcode:
  I summarize the statistical, physical, and morphological properties
  of coronal mass ejections (CMEs) of solar cycle 23, as observed by the
  Solar and Heliospheric Observatory (SOHO) mission. The SOHO data is by
  far the most extensive data, which made it possible to fully establish
  the properties of CMEs as a phenomenon of utmost importance to Sun-Earth
  connection as well as to the heliosphere. I also discuss various subsets
  of CMEs that are of primary importance for their impact on Earth.

---------------------------------------------------------
Title: On the Rates of Coronal Mass Ejections: Remote Solar and In
    Situ Observations
Authors: Riley, Pete; Schatzman, C.; Cane, H. V.; Richardson, I. G.;
   Gopalswamy, N.
2006ApJ...647..648R    Altcode:
  We compare the rates of coronal mass ejections (CMEs) as inferred from
  remote solar observations and interplanetary CMEs (ICMEs) as inferred
  from in situ observations at both 1 AU and Ulysses from 1996 through
  2004. We also distinguish between those ICMEs that contain a magnetic
  cloud (MC) and those that do not. While the rates of CMEs and ICMEs
  track each other well at solar minimum, they diverge significantly
  in early 1998, during the ascending phase of the solar cycle, with
  the remote solar observations yielding approximately 20 times more
  events than are seen at 1 AU. This divergence persists through 2004. A
  similar divergence occurs between MCs and non-MC ICMEs. We argue that
  these divergences are due to the birth of midlatitude active regions,
  which are the sites of a distinct population of CMEs, only partially
  intercepted by Earth, and we present a simple geometric argument showing
  that the CME and ICME rates are consistent with one another. We also
  acknowledge contributions from (1) an increased rate of high-latitude
  CMEs and (2) focusing effects from the global solar field. While our
  analysis, coupled with numerical modeling results, generally supports
  the interpretation that whether one observes a MC within an ICME is
  sensitive to the trajectory of the spacecraft through the ICME (i.e.,
  an observational selection effect), one result directly contradicts
  it. Specifically, we find no systematic offset between the latitudinal
  origin of ICMEs that contain MCs at 1 AU in the ecliptic plane and
  that of those that do not.

---------------------------------------------------------
Title: Solar Energetic Particles and CME-driven Shocks
Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Bougeret, J. -L.
2006IAUJD...1E..54G    Altcode:
  Large solar energetic particle (SEP) events are associated with
  coronal mass ejections (CMEs) of very high speed (~1500 km/s). A mass
  mtion of such high speeds in the coronal and interplanetary plasma
  has to drive fast mode MHD shocks. Direct evidence of such shocks
  come from in situ observations of shock arriving at 1 AU immediately
  followed by the driving CMEs. The energetic storm particle (ESP)
  events associated with these shocks present direct evidence for shock
  acceleration. Shocks near the Sun have to be remote-sensed using type
  II bursts of type II. Type II bursts occurring over wide range of
  wavelengths are known to be associated with very fast and wide CMEs
  (Gopalswamy et al., 2005). We analyze a set of such type II bursts
  observed during solar cycle 23 and the associated SEP and CME events
  to explore the relationship bewteen CME-driven shocks and SEPs near the
  Sun. We also study the association of the type II burst events with the
  interplanetary shocks observed in situ and ESP events. The main result
  is that when the CME associated with the type II bursts originate on
  the disk center of the Sun, they result in shocks at 1 AU followed by
  driving CMEs. We also discuss the relationship bewteen type II bursts
  and ESP events. Reference: Gopalswamy, N., E. Aguilar-Rodriguez,
  S. Yashiro, S. Nunes, M. L. Kaiser, and R. A. Howard, Type II radio
  bursts and energetic solar eruptions, JGRA, 110, 12, 2005

---------------------------------------------------------
Title: Mission Concepts for Spacecraft and Lunar-based Radio Source
    Imaging at Frequencies below the Ionospheric Cutoff
Authors: Gopalswamy, N.; MacDowall, R. J.; Kaiser, M. L.; Demaio,
   L. D.; Bale, S. D.; Howard, R. E.; Jones, D. L.; Kasper, J. C.;
   Kassim, N. E.; Lazio, J. W.; Weiler, K. W.; Reiner, M. J.
2006IAUJD..12E..21G    Altcode:
  No present or approved spacecraft mission has the capability to
  provide high angular resolution imaging of solar or magnetospheric
  radio bursts or of the celestial sphere at frequencies below the
  ionospheric cutoff. In this presentation, we review briefly the history
  of space-based radio observations by single spacecraft. Although
  these missions did not produce images of discrete radio sources,
  they did establish important constraints for future imaging
  missions. Subsequently, we present in detail an active NASA mission
  proposal to perform such imaging in the frequency range ~30 kHz to
  15 MHz. The focus of this mission, the Solar Imaging Radio Array
  (SIRA), is solar and NASA exploration-oriented, with emphasis on
  improved understanding and space weather application of radio bursts
  associated with solar energetic particle (SEP) events and on tracking
  shocks and other components of coronal mass ejections (CMEs). SIRA
  will also map the astrophysical sky. SIRA will require a minimum of 12
  to 16 micro-satellites to establish a sufficient number of baselines
  with separations on the order of a kilometer. The baseline microsat is
  3-axis stabilized with body-mounted solar arrays and an articulated,
  earth pointing high gain antenna. The constellation will likely
  be placed in an L1 halo orbit, which is the preferred location for
  full-time solar observations. We will also discuss follow-on missions
  that would be lunar-based, ultimately with of order 10,000 dipole
  antennas. The lunar missions would be adaptations of ground-based
  interferometric arrays like LOFAR, LWA, MWA, etc. Basic research in
  radio astronomy at the Naval Research Laboratory is supported by the
  Office of Naval Research; part of this work is being carried out at
  the Jet Propulsion Laboratory, California Institute of Technology,
  under contract with the National Aeronautics and Space Administration.

---------------------------------------------------------
Title: The IHY Program and Associated IAU Activities
Authors: Webb, D.; Gopalswamy, N.
2006IAUSS...5E..43W    Altcode:
  The International Heliospheric Year is an international program of
  scientific collaboration planned for the time period starting next
  year, the 50th anniversary of the International Geophysical Year. The
  physical realm of the IHY encompasses all of the solar system out
  to the interstellar medium, representing a direct connection between
  in-situ and remote observations. The IHY is of great interest to the
  IAU because of this broad astronomical coverage as well as its emphasis
  on international cooperation and developing nations. The IHY program
  is promoting worldwide participation in its activities that include
  dispersing networks of inexpensive instrumentation to achieve its
  scientific goals. Within the IAU the IHY program is organized under
  Division II, which covers the Sun and Heliosphere. Nat Gopalswamy
  is the IHY International Coordinator and Chair of the IHY subgroup
  within the IAU's Working Group on International Collaboration on
  Space Weather. David Webb is the IAU representative for the IHY and
  the outgoing President of Division II. The United Nations IHY effort
  is led by Hans Haubold under the UNBSS program and will be discussed
  next by Dr. Gopalswamy. Under this program the IAU is supporting the
  annual IHY Workshops and is facilitating the communications between
  scientists in developed and developing countries.

---------------------------------------------------------
Title: Correction to “Introduction to special section on corotating
    solar wind streams and recurrent geomagnetic activity”
Authors: Tsurutani, B. T.; McPherron, R. L.; Gonzalez, W. D.; Lu,
   G.; Sobral, J. H. A.; Gopalswamy, N.
2006JGRA..111.8S90T    Altcode: 2006JGRA..11108S90T
  No abstract at ADS

---------------------------------------------------------
Title: Anemone structure of Active Region NOAA 10798 and related
    geo-effective flares/ CMEs
Authors: Asai, A.; Ishii, T. T.; Shibata, K.; Gopalswamy, N.
2006IAUJD...3E..72A    Altcode:
  Introduction: We report the evolution and the coronal features of an
  active region NOAA 10798, and the related magnetic storms. Method:
  We examined in detail the photospheric and coronal features of
  the active region by using observational data in soft X-rays, in
  extreme ultraviolet images, and in magnetogram obtained with GOES,
  SOHO satellites. We also examined the interplanetary disturbances from
  the ACE data. Results: This active region was located in the middle of
  a small coronal hole, and generated 3 M-class flares. The flares are
  associated with high speed CMEs up to 2000 km/s. The interplanetary
  disturbances also show a structure with southward strong magnetic
  field. These produced a magnetic storm on 2005 August 24. Conclusions:
  The anemone structure may play a role for producing the high-speed
  and geo-effective CMEs even the near limb locations.

---------------------------------------------------------
Title: The United Nations Basic Space Science Initiative for IHY 2007
Authors: Gopalswamy, N.; Davila, J. M.; Thompson, B. J.; Haubold, H.
2006IAUSS...5E..47G    Altcode:
  The United Nations, in cooperation with national and international
  space-related agencies and organizations, has been organizing annual
  workshops since 1990 on basic space science, particularly for the
  benefit of scientists and engineers from developing nations. The United
  Nations Office for Outer Space Affairs, through the IHY Secretariat and
  the United Nations Basic Space Science Initiative (UNBSSI) will assist
  scientists and engineers from all over the world in participating in
  the International Heliophysical Year (IHY) 2007. A major thrust of the
  IHY/UNBSSI program is to deploy arrays of small, inexpensive instruments
  such as magnetometers, radio telescopes, GPS receivers, all-sky cameras,
  etc. around the world to provide global measurements of ionospheric
  and heliospheric phenomena. The small instrument program is envisioned
  as a partnership between instrument providers, and instrument hosts in
  developing countries. The lead scientist will provide the instruments
  (or fabrication plans for instruments) in the array; the host country
  will provide manpower, facilities, and operational support to obtain
  data with the instrument typically at a local university. Funds
  are not available through the IHY to build the instruments; these
  must be obtained through the normal proposal channels. However all
  instrument operational support for local scientists, facilities, data
  acquisition, etc will be provided by the host nation. It is our hope
  that the IHY/UNBSSI program can facilitate the deployment of several of
  these networks world wide. Existing data bases and relevant software
  tools that can will be identified to promote space science activities
  in developing countries. Extensive data on space science have been
  accumulated by a number of space missions. Similarly, long-term data
  bases are available from ground based observations. These data can be
  utilized in ways different from originally intended for understanding
  the heliophysical processes. This paper provides an overview of the
  IHY/UNBSS program, its achievements and future plans.

---------------------------------------------------------
Title: Observational Properties of CMEs from a Decade-Long
    Observations by SOHO
Authors: Gopalswamy, N.; Yashiro, S.; Howard, R. A.
2006ESASP.617E.129G    Altcode: 2006soho...17E.129G
  No abstract at ADS

---------------------------------------------------------
Title: Introduction to special section on corotating solar wind
    streams and recurrent geomagnetic activity
Authors: Tsurutani, Bruce T.; McPherron, Robert L.; Gonzalez, Walter
   D.; Lu, Gang; Sobral, Jose H. A.; Gopalswamy, Nat
2006JGRA..111.7S00T    Altcode: 2006JGRA..11107S00T
  No abstract at ADS

---------------------------------------------------------
Title: Corotating solar wind streams and recurrent geomagnetic
activity: A review
Authors: Tsurutani, Bruce T.; Gonzalez, Walter D.; Gonzalez, Alicia
   L. C.; Guarnieri, Fernando L.; Gopalswamy, Nat; Grande, Manuel;
   Kamide, Yohsuke; Kasahara, Yoshiya; Lu, Gang; Mann, Ian; McPherron,
   Robert; Soraas, Finn; Vasyliunas, Vytenis
2006JGRA..111.7S01T    Altcode: 2006JGRA..11107S01T
  Solar wind fast streams emanating from solar coronal holes cause
  recurrent, moderate intensity geomagnetic activity at Earth. Intense
  magnetic field regions called Corotating Interaction Regions or CIRs
  are created by the interaction of fast streams with upstream slow
  streams. Because of the highly oscillatory nature of the GSM magnetic
  field z component within CIRs, the resultant magnetic storms are
  typically only weak to moderate in intensity. CIR-generated magnetic
  storm main phases of intensity Dst &lt; -100 nT (major storms) are
  rare. The elongated storm "recovery" phases which are characterized
  by continuous AE activity that can last for up to 27 days (a solar
  rotation) are caused by nonlinear Alfven waves within the high streams
  proper. Magnetic reconnection associated with the southward (GSM)
  components of the Alfvén waves is the solar wind energy transfer
  mechanism. The acceleration of relativistic electrons occurs during
  these magnetic storm "recovery" phases. The magnetic reconnection
  associated with the Alfvén waves cause continuous, shallow injections
  of plasma sheet plasma into the magnetosphere. The asymmetric plasma is
  unstable to wave (chorus and other modes) growth, a feature central to
  many theories of electron acceleration. It is noted that the continuous
  AE activity is not a series of substorm expansion phases. Arguments
  are also presented why these AE activity intervals are not convection
  bays. The auroras during these continuous AE activity intervals are
  less intense than substorm auroras and are global (both dayside and
  nightside) in nature. Owing to the continuous nature of this activity,
  it is possible that there is greater average energy input into the
  magnetosphere/ionosphere system during far declining phases of the solar
  cycle compared with those during solar maximum. The discontinuities
  and magnetic decreases (MDs) associated with interplanetary Alfven
  waves may be important for geomagnetic activity. In conclusion,
  it will be shown that geomagnetic storms associated with high-speed
  streams/CIRs will have the same initial, main, and "recovery" phases
  as those associated with ICME-related magnetic storms but that the
  interplanetary causes are considerably different.

---------------------------------------------------------
Title: Coronal and Interplanetary Type II Bursts
Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.
2006SPD....37.2501G    Altcode: 2006BAAS...38..251G
  The kinetic energy of coronal mass ejections (CMEs) has been
  shown to essentially decide the wavelength range over which type
  II radio emission occurs. The larger the kinetic energy the wider
  is the wavelength range over which emission takes place. In other
  words, CMEs with larger kinetic energy drive shocks farther into the
  interplanetary medium. We studied a set of about 70 type II bursts that
  had emission components in the three well-known wavelength domains:
  metric (m), decameter-hectometric (DH), and kilometric (km). We find
  that the properties of CMEs associated with the m-to-km type II bursts
  are nearly identical to those CMEs associated with solar energetic
  particle events. We suggest that this correlation is evidence for
  the same shock accelerating electrons and ions. Next we examined the
  time delay between the onsets of metric and interplanetary type II
  emission. This is an important parameter because only when a metric
  type II burst has IP counterpart, it is likely to have space weather
  consequences. We find that the typical delay is about 1 hour. This is
  sufficiently small that one can use the DH type II bursts to identify
  shocks that might impact various destinations in the inner heliosphere.

---------------------------------------------------------
Title: Comment on “Interplanetary shocks unconnected with earthbound
    coronal mass ejections” by T. A. Howard and S. J. Tappin
Authors: Gopalswamy, Nat; Akiyama, Sachiko; Yashiro, Seiji; Kasper, J.
2006GeoRL..3311108G    Altcode:
  <A href="/journals/gl/gl0611/2005GL024983/">Abstract Available</A>
  from <A href="http://www.agu.org">http://www.agu.org</A>

---------------------------------------------------------
Title: Are halo coronal mass ejections special events?
Authors: Lara, Alejandro; Gopalswamy, Nat; Xie, Hong; Mendoza-Torres,
   Eduardo; PéRez-EríQuez, RomáN.; Michalek, Gregory
2006JGRA..111.6107L    Altcode: 2006JGRA..11106107L
  We revisited the properties of wide coronal mass ejections (CMEs)
  called halo CMEs. Using the large LASCO/SOHO CMEs data set, from 1996
  to 2004, we examined the statistical properties of (partial and full)
  halo CMEs and compare with the same properties of "normal" width (lower
  than 120°) CMEs. We found that halo CMEs have different properties than
  "normal" CMEs, which cannot be explained merely by the current geometric
  interpretation that they are seen as halos because they are traveling
  in the Sun Earth direction. We found that the CME width distribution
  is formed by, at least, three different populations: Two gaussians:
  a narrow and a medium distribution centered at ∼17° and ∼38°,
  respectively; the narrow population most likely corresponds to the
  "true" observed widths, whereas the medium width population is the
  product of projection effects. The third distribution corresponds
  to wider CMEs (80° &lt; W &lt; 210°) which behaves as a power
  law. Partial and full halo CMEs wider than these do not follow any
  particular distribution. This lack of regularity may be due to the
  small number of such events. In particular, we found (and test by a
  statistical approach) that the number of observed full halo CMEs is
  lower than expected. The CME speed follows a log-normal distribution,
  except for the very low speed CME population, which follows a gaussian
  distribution centered at ∼100 km/s and is probably due to projection
  effects. When the CMEs are divided by width into nonhalo, partial
  halo, and full halo, we found that the peaks of the distributions
  are shifted toward higher speeds, ∼300, ∼400 and ∼600 km/s for
  nonhalo, partial halo, and full halo CMEs, respectively. This confirms
  that halo CMEs tend to be high speed CMEs. The acceleration of full
  halo CMEs tends to be more negative compared with nonhalo and partial
  halo CMEs. We introduce a new observational CME parameter: The final
  observed distance (FOD), i.e., the highest point within the coronograph
  field of view where a CME can be distinguished from the background. In
  other words, the highest CME altitude measured. The FOD for nonhalo CMEs
  decreases exponentially from ∼5 to ∼30 R<SUB>⊙</SUB> in the LASCO
  field of view. On the other hand, the FOD of halo CMEs increase with
  distance. This means that it is more likely to see halo CMEs at large
  distances (from the Sun) than nonhalo CMEs. These halo CME properties
  may be explained if the white light wide enhancements (or halo) seen
  by coronographs correspond to a combination of an expanding (shock)
  wave which disturbs and/or compresses the ambient material and the
  CME material itself.

---------------------------------------------------------
Title: Preface
Authors: Gopalswamy, Nat
2006JApA...27...57G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Properties of Interplanetary Coronal Mass Ejections
Authors: Gopalswamy, Nat
2006SSRv..124..145G    Altcode: 2007SSRv..tmp...53G
  Interplanetary coronal mass ejections (ICMEs) originating from closed
  field regions on the Sun are the most energetic phenomenon in the
  heliosphere. They cause intense geomagnetic storms and drive fast mode
  shocks that accelerate charged particles. ICMEs are the interplanetary
  manifestations of CMEs typically remote-sensed by coronagraphs. This
  paper summarizes the observational properties of ICMEs with reference
  to the ordinary solar wind and the progenitor CMEs.

---------------------------------------------------------
Title: Solar Imaging Radio Array: Space-based Radio Imaging at
    Frequencies Below the Ionospheric Cutoff
Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Demaio,
   L. D.; Bale, S. D.; Kasper, J. C.; Lazarus, A. J.; Howard, R. E.;
   Jones, D. L.; Reiner, M. J.; Weiler, K. W.
2006AGUSMSH33A..11M    Altcode:
  No present or approved spacecraft mission has the capability to provide
  high angular resolution imaging of solar or magnetospheric radio
  bursts or of the celestial sphere at frequencies below the ionospheric
  cutoff. In this presentation, we review a NASA MIDEX-class mission
  to perform such imaging in the frequency range 30 kHz to 15 MHz. The
  focus of the mission, the Solar Imaging Radio Array (SIRA), is solar
  and exploration- oriented, with emphasis on improved understanding and
  application of radio bursts associated with solar energetic particle
  (SEP) events and on tracking shocks and other components of coronal
  mass ejections (CMEs). The data stream will also permit high angular
  resolution mapping of the celestial sphere at frequencies below 15 MHz,
  permitting detection of numerous astrophysical objects and extension of
  their observed spectra to much lower frequencies. SIRA will require 12
  to 16 micro-satellites to establish a sufficient number of baselines
  with separations on the order of kilometers. The constellation
  consists of microsats located quasi-randomly on a spherical shell,
  initially of radius 5 km. The baseline microsat is 3-axis stabilized
  with body-mounted solar arrays and an articulated, Earth-pointing high
  gain antenna. The constellation will likely be placed at L1, which
  is the preferred location for full-time solar observations. Detailed
  mission science and technology goals will be reviewed.

---------------------------------------------------------
Title: On the rates of coronal mass ejections: remote solar and in
    situ observations
Authors: Riley, P.; Cane, H.; Richardson, I. G.; Gopalswamy, N.;
   Linker, J. A.; Mikic, Z.; Lionello, R.
2006AGUSMSA21A..01R    Altcode:
  In this study we compare the rates of coronal mass ejections (CMEs)
  as inferred from remote solar observations and interplanetary CMEs
  (ICMEs) as inferred from in situ observations at both 1 AU and Ulysses
  for almost an entire solar cycle (1996 through 2004). We find that,
  while the rates of CMEs and ICMEs track each other well at solar
  minimum, they diverge significantly in early 1998, during the ascending
  phase of the solar cycle, with the remote solar observations yielding
  approximately 20 times more events than are seen in situ at 1 AU. This
  divergence persists through 2004. We discuss several possible causes,
  including: (1) the appearance of mid-latitude active regions; (2)
  the increased rate of high-latitude CMEs; and (3) the strength of the
  global solar field. We conclude that the most likely interpretation
  is that this divergence is due to the birth of mid-latitude active
  regions, which are the sites of a distinct population of CMEs that are
  only partially intercepted by Earth. This conclusion is supported by
  the following points: (1) A similar divergence occurs between ICMEs in
  which magnetic clouds are observed (MCs), and those that are not; and
  (2) a number of pronounced enhancements in the CME rate, separated
  by approximately one year, are also mirrored and in ICME rate, but
  not obviously in the MC rate. We provide a simple geometric argument
  that shows that the computed CME and ICME rates are consistent with
  each other. The origins of the individual peaks can be traced back
  to unusually strong active regions on the Sun. Taken together, these
  results suggest that whether one observes a flux rope within an ICME
  is sensitive to the trajectory of the spacecraft through the ICME,
  i.e., an observational selection effect. This conclusion is supported
  by models of CME eruption and evolution, which: (1) are incapable of
  producing a CME that does not contain an embedded flux rope; and (2)
  demonstrate that glancing intercepts can produce ICME-like signatures
  without the magnetic structures associated with a flux rope

---------------------------------------------------------
Title: A Sun-to-Earth Campaign Joining Observations from the Great
    Observatory with Worldwide Satellite and Ground-Based Resources to
    Investigate System Science Frontiers
Authors: Kozyra, J. U.; Shibata, K.; Barnes, R. J.; Basu, S.; Davila,
   J. M.; Fox, N. J.; Gopalswamy, N.; Kuznetsova, M. M.; Pallamraju,
   D.; Paxton, L. J.; Ridley, A.; Weiss, M.; Young, C. A.; Zanetti, L. J.
2006AGUSMSM23A..03K    Altcode:
  An Internet-based cross-disciplinary analysis campaign that will
  make heavy use of Great Observatory missions as well as international
  satellite and ground-based assets is being undertaken with joint support
  from the CAWSES, IHY, LWS, and ICESTAR programs planned for late
  April or early May 2006. An evolving list of open science questions
  that serve as sun-to-Earth focus areas for the worldwide campaign
  were identified during a small interdisciplinary CAWSES workshop
  at Stanford University in December 2005 as well as during a joint
  CAWSES/ICESTAR session at the CEDAR meeting in Boulder the preceding
  summer. The analysis campaign will take place over the Internet in the
  form of virtual poster sessions with message boards and monitors that
  summarize the important science issues and new results daily. Poster
  authors will be asked to closely monitor their message boards during
  the day of their poster session as well as the following day. Outreach
  to other disciplines and international students will take the form of
  tutorial talks that place campaign science issues into the context of
  the current state of knowledge in each discipline area. Global models
  and data sets (TEC, magnetometer maps, ULF wave maps, assimilative
  models, MHD model outputs, continuous solar images) will be available
  to provide context for local and regional observations. The Community
  Coordinated Data Center (CCMC) is developing a small number of new data
  display formats that extract data from global models and place it in
  the same format as the observations either for ground-based stations
  or along satellite tracks. Other ideas being explored include real
  time upload of additional posters in response to issues raised during
  the poster session, library of related articles, reference archive of
  observations, etc. A summary of which aspects and/or tools worked and
  which were less useful will be presented.

---------------------------------------------------------
Title: Radio manifestation of the interaction between ultra-fast CMEs
Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.
2006AGUSMSH24A..03G    Altcode:
  Active region 720 was one of the super active regions of cycle 23
  in that it produced large numbers of coronal mass ejections (CMEs)
  and major flares. The average recurrence time between flares in the
  region was about 2.5 h, but several flares and CMEs occurred with
  much shorter recurrence time. In this paper, we are concerned with
  two ultra-fast CMEs (speed &gt; 2000 km/s) originating within 45
  minutes. The CMEs merged with each other within the field of view of
  SOHO coronagraphs. Both CMEs were associated with long wavelength
  type II radio bursts. The type II burst associated with the first
  CME was normal, while that associated with the second CME showed
  irregular spectral behavior, including a characteristic broadband
  enhancement. Solar energetic particles (SEPs) associated with the
  two CMEs also showed some peculiarities, which are consistent with
  the interaction between the two CMEs. The SEP intensity reached a
  very high value around the time of interaction. We present radio and
  white light observations of the CMEs and provide an interpretation
  of the observed spectral features in the radio dynamic spectrum. Work
  supported by NASA's LWS TR&amp;T and SR&amp;T programs.

---------------------------------------------------------
Title: Science Plans for the International Heliophysical Year
Authors: Davila, J. M.; Gopalswamy, N.; Harrison, R. A.; Stamper,
   R.; Briand, C.; Potgieter, M. S.
2006AGUSM.U34A..04D    Altcode:
  On October 4, 1957, only 53 years after the beginning of flight in Kitty
  Hawk, the launch of Sputnik 1 marked the beginning of the space age;
  as mankind took the first steps to leaving the protected environment of
  Earth's atmosphere. Discovery of the radiation belts, the solar wind,
  and the structure of Earth's magnetosphere prepared the way for the
  inevitable human exploration to follow. Soon, Cosmonauts and Astronauts
  orbited Earth, and then in 1969, Astronauts landed on the Moon. Today
  a similar story is unfolding, the spacecraft Voyager has crossed the
  termination shock, and will soon leave the heliosphere. For the first
  time, man will begin to explore the local interstellar medium. It is
  inevitable that, during the next 50 years, exploration of the solar
  system including the Moon, Mars and the outer planets will be the
  focus of the space program, and like 50 years ago, unmanned probes
  will lead the way, followed by human exploration. The International
  Geophysical Year (IGY) of 1957, a broad-based and all-encompassing
  effort to push the frontiers of geophysics, resulted in a tremendous
  increase of knowledge in space physics, Sun-Earth Connection, planetary
  science and the heliosphere in general. Now, 50 years later, we have
  the unique opportunity to further advance our knowledge of the global
  heliosphere and its interaction with the interstellar medium through
  the International Heliophysical Year (IHY) in 2007, and to raise
  public awareness of space physics. This presentation will focus on
  global science planning efforts and campaigns for all participating
  IHY nations.

---------------------------------------------------------
Title: United Nations Basic Space Science Initiative Programme for
    the International Heliophysical Year 2007
Authors: Gopalswamy, Nat
2006UNPSA..17...47G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Pre-CME Sun
Authors: Gopalswamy, N.; Mikić, Z.; Maia, D.; Alexander, D.; Cremades,
   H.; Kaufmann, P.; Tripathi, D.; Wang, Y. -M.
2006SSRv..123..303G    Altcode: 2006SSRv..tmp...77G
  The coronal mass ejection (CME) phenomenon occurs in closed magnetic
  field regions on the Sun such as active regions, filament regions,
  transequatorial interconnection regions, and complexes involving a
  combination of these. This chapter describes the current knowledge
  on these closed field structures and how they lead to CMEs. After
  describing the specific magnetic structures observed in the CME source
  region, we compare the substructures of CMEs to what is observed before
  eruption. Evolution of the closed magnetic structures in response to
  various photospheric motions over different time scales (convection,
  differential rotation, meridional circulation) somehow leads to the
  eruption. We describe this pre-eruption evolution and attempt to link
  them to the observed features of CMEs. Small-scale energetic signatures
  in the form of electron acceleration (signified by nonthermal radio
  bursts at metric wavelengths) and plasma heating (observed as compact
  soft X-ray brightening) may be indicative of impending CMEs. We survey
  these pre-eruptive energy releases using observations taken before
  and during the eruption of several CMEs. Finally, we discuss how the
  observations can be converted into useful inputs to numerical models
  that can describe the CME initiation.

---------------------------------------------------------
Title: Coronal Observations of CMEs.  Report of Working Group A
Authors: Schwenn, R.; Raymond, J. C.; Alexander, D.; Ciaravella, A.;
   Gopalswamy, N.; Howard, R.; Hudson, H.; Kaufmann, P.; Klassen, A.;
   Maia, D.; Munoz-Martinez, G.; Pick, M.; Reiner, M.; Srivastava, N.;
   Tripathi, D.; Vourlidas, A.; Wang, Y. -M.; Zhang, J.
2006SSRv..123..127S    Altcode: 2006SSRv..tmp...58S
  CMEs have been observed for over 30 years with a wide variety of
  instruments. It is now possible to derive detailed and quantitative
  information on CME morphology, velocity, acceleration and mass. Flares
  associated with CMEs are observed in X-rays, and several different
  radio signatures are also seen. Optical and UV spectra of CMEs both on
  the disk and at the limb provide velocities along the line of sight
  and diagnostics for temperature, density and composition. From the
  vast quantity of data we attempt to synthesize the current state of
  knowledge of the properties of CMEs, along with some specific observed
  characteristics that illuminate the physical processes occurring during
  CME eruption. These include the common three-part structures of CMEs,
  which is generally attributed to compressed material at the leading
  edge, a low-density magnetic bubble and dense prominence gas. Signatures
  of shock waves are seen, but the location of these shocks relative
  to the other structures and the occurrence rate at the heights where
  Solar Energetic Particles are produced remains controversial. The
  relationships among CMEs, Moreton waves, EIT waves, and EUV dimming
  are also cloudy. The close connection between CMEs and flares suggests
  that magnetic reconnection plays an important role in CME eruption
  and evolution. We discuss the evidence for reconnection in current
  sheets from white-light, X-ray, radio and UV observations. Finally, we
  summarize the requirements for future instrumentation that might answer
  the outstanding questions and the opportunities that new space-based
  and ground-based observatories will provide in the future.

---------------------------------------------------------
Title: Planning the International Heliophysical Year (IHY)
Authors: Davila, Joseph M.; Thompson, Barbara J.; Gopalswamy, Nat
2006UNPSA..17...37D    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Long-lived geomagnetic storms and coronal mass ejections
Authors: Xie, H.; Gopalswamy, N.; Manoharan, P. K.; Lara, A.; Yashiro,
   S.; Lepri, S.
2006JGRA..111.1103X    Altcode: 2006JGRA..11101103X
  Coronal mass ejections (CMEs) are major solar events that are known to
  cause large geomagnetic storms (Dst &lt; -100 nT). Isolated geomagnetic
  storms typically have a main phase of 3-12 hours and a recovery phase
  of around 1 day. However, there are some storms with main and recovery
  phases exceeding ∼3 days. We trace the origin of these long-lived
  geomagnetic storms (LLGMS) to frontside halo CMEs. We studied 37 LLGMS
  events with Dst &lt; -100 nT and the associated CMEs which occurred
  during 1998-2002. It is found that LLGMS events are caused by (1)
  successive CMEs, accounting for ∼64.9% (24 of 37); (2) single CMEs,
  accounting for ∼21.6% (8 of 37); and (3) high-speed streams (HSS) in
  corotating interaction regions (CIRs) with no related CME, accounting
  for ∼13.5% (5 of 37). The long duration of the LLGMS events was found
  to be due to successive CMEs and HSS events; the high intensity of the
  LLGMS events was related to the interaction of CMEs with other CMEs and
  HSS events. We find that the duration of LLGMS is well correlated to the
  number of participating CMEs (correlation coefficient r = 0.78). We also
  find that the intensity of LLGMS has a good correlation with the degree
  of interaction (the number of CMEs interacting with a HSS event or with
  themselves) (r = 0.67). The role of preconditioning in LLGMS events,
  where the Dst development occurred in multiple steps in the main and
  recovery phases, has been investigated. It is found that preconditioning
  does not affect the main phase of the LLGMS events, while it plays an
  important role during the recovery phase of the LLGMS events.

---------------------------------------------------------
Title: Composition and magnetic structure of interplanetary coronal
    mass ejections at 1 AU
Authors: Aguilar-Rodriguez, E.; Blanco-Cano, X.; Gopalswamy, N.
2006AdSpR..38..522A    Altcode:
  We study the magnetic structure and charge state ratio of
  interplanetary coronal mass ejections (ICMEs) observed by ACE and Wind
  spacecraft. Measurements of abundances and charge state ratio of heavy
  ions (e.g. O<SUP>7+</SUP>/O<SUP>6+</SUP>, C<SUP>6+</SUP>/C<SUP>5+</SUP>,
  and Mg<SUP>10+</SUP>/O<SUP>6+</SUP>) in the plasma as well as magnetic
  field structure are important tracers for physical conditions and
  processes in the source regions of ICMEs. We used ion composition
  (from ACE), plasma (from Wind) and magnetic field (from Wind and ACE)
  data from 1998 to 2002. Using the low proton temperature criterion,
  a common plasma signature of ICMEs, we identified 154 events which
  include magnetic clouds, non-cloud ejecta and complex ICMEs. The
  latter one refers to compound events resulting from the overtaking
  of successive ICMEs which can include both magnetic clouds and
  non-cloud ejecta. We find that there is a close relationship between
  the increase in the charge state ionization factor and the magnetic
  structure of ICMEs. Events with magnetic cloud topology show higher
  Q<SUB></SUB>andQ<SUB></SUB> charge state ratios than those with
  non-magnetic cloud structure. However, both magnetic cloud and non-cloud
  events show an increase in these ratios when compared with the ambient
  solar wind. In contrast, perhaps due to instrumental effects, the charge
  state ratio Q<SUB></SUB> for all events does not show a real enhancement
  when compared with the ambient solar wind. The difference in ionization
  states between non-cloud ejecta and magnetic clouds is more pronounced
  in fast solar wind than when events are embedded in slow wind.

---------------------------------------------------------
Title: Associations of Coronal Mass Ejections as a function of X-ray
    Flare Properties
Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.; Howard, R. A.
2006cosp...36.1778Y    Altcode: 2006cosp.meet.1778Y
  We examined the associations between coronal mass ejections CMEs and
  X-ray flares using data from the Large Angle Spectrometric Coronagraph
  LASCO on board the Solar and Heliospheric Observatory SOHO The CME
  association of 1540 X-ray flares M classand above detected by GOES
  satellite were examined As reported in previous studies the CME
  association rate clearly increased with the peak X-ray intensity the
  total X-ray intensity and the decay time The CME association rate
  increased from 40 flare size between M1 0 and M1 7 to 98 flare size
  above X1 8 Except for an X3 6 flare on July 16 2004 all the 50 huge
  flares above X1 8 definitely have associated CMEs Furthermore all
  the X-ray flares with a decay time exceeding 90 min were associated
  CMEs We discuss which X-ray parameters are essential in order to have
  CME association

---------------------------------------------------------
Title: Solar wind speed within 20 R<SUB>S</SUB> of the Sun estimated
    from limb coronal mass ejections
Authors: Nakagawa, Tomoko; Gopalswamy, Nat; Yashiro, Seiji
2006JGRA..111.1108N    Altcode: 2006JGRA..11101108N
  An estimation of the solar wind speed in the vicinity of the Sun
  is carried out using the initial speed and acceleration of coronal
  mass ejections (CMEs) that appeared close to the solar limb. A linear
  relationship was found between the initial acceleration and the speed of
  the limb CMEs. It appears that a dragging force is acting on the CMEs,
  depending on the speed difference between the CMEs and the ambient
  plasma. The ambient solar wind speed within 20 solar radii estimated
  from low-latitude CMEs during 1998-2003 ranged from 100 to 700 km
  s<SUP>-1</SUP>, while the solar wind speed measured at 1 AU ranged
  from 300 to 700 km s<SUP>-1</SUP>. The estimated solar wind speeds
  in the vicinity of the Sun sometimes agreed with the simultaneous in
  situ measurements at 1 AU, but in other periods they were slower than
  the speeds measured at 1 AU. It is suggested that most of the time
  the low-latitude solar wind completes accelerating within 20 solar
  radii, but occasionally additional acceleration is present beyond 20
  solar radii.

---------------------------------------------------------
Title: Coronal mass ejections and space weather due to extreme events
Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.
2006ilws.conf...79G    Altcode:
  This paper summarizes the extreme solar activity and its space
  weather implications during the declining phase of the solar cycle 23:
  October-November 2003 (AR 486), November 2004 (AR 696), January 2005
  (AR 720), and September 2005 (AR 808). We have compiled and compared the
  properties of eruptions and the underlying active regions. All these
  are super active regions, but the flare and CME productivity varied
  significantly. While the CMEs from all the regions kept the level of
  solar energetic particles (SEPs) at storm level for several days,
  their geoeffectiveness (the ability to produce geomagnetic storms)
  was significantly different, probably due to the location of the
  eruptions on the Sun.

---------------------------------------------------------
Title: Coronal Observations of CMEs
Authors: Schwenn, R.; Raymond, J. C.; Alexander, D.; Ciaravella, A.;
   Gopalswamy, N.; Howard, R.; Hudson, H.; Kaufmann, P.; Klassen, A.;
   Maia, D.; Munoz-Martinez, G.; Pick, M.; Reiner, M.; Srivastava, N.;
   Tripathi, D.; Vourlidas, A.; Wang, Y. -M.; Zhang, J.
2006cme..book..127S    Altcode:
  CMEs have been observed for over 30 years with a wide variety of
  instruments. It is now possible to derive detailed and quantitative
  information on CME morphology, velocity, acceleration and mass. Flares
  associated with CMEs are observed in X-rays, and several different
  radio signatures are also seen. Optical and UV spectra of CMEs both on
  the disk and at the limb provide velocities along the line of sight
  and diagnostics for temperature, density and composition. From the
  vast quantity of data we attempt to synthesize the current state of
  knowledge of the properties of CMEs, along with some specific observed
  characteristics that illuminate the physical processes occurring during
  CME eruption. These include the common three-part structures of CMEs,
  which is generally attributed to compressed material at the leading
  edge, a low-density magnetic bubble and dense prominence gas. Signatures
  of shock waves are seen, but the location of these shocks relative
  to the other structures and the occurrence rate at the heights where
  Solar Energetic Particles are produced remains controversial. The
  relationships among CMEs, Moreton waves, EIT waves, and EUV dimming
  are also cloudy. The close connection between CMEs and flares suggests
  that magnetic reconnection plays an important role in CME eruption
  and evolution. We discuss the evidence for reconnection in current
  sheets from white-light, X-ray, radio and UV observations. Finally, we
  summarize the requirements for future instrumentation that might answer
  the outstanding questions and the opportunities that new space-based
  and ground-based observatories will provide in the future.

---------------------------------------------------------
Title: Coronal mass ejections and space weather
Authors: Webb, D. F.; Gopalswamy, N.
2006ilws.conf...71W    Altcode:
  Coronal mass ejections (CMEs) are a key feature of coronal and
  interplanetary (IP) dynamics. Major CMEs inject large amounts of mass
  and magnetic fields into the heliosphere and, when aimed Earthward,
  can cause major geomagnetic storms and drive IP shocks, a key source
  of solar energetic particles. Studies over this solar cycle using the
  excellent data sets from the SOHO, TRACE, Yohkoh, Wind, ACE and other
  spacecraft and ground-based instruments have improved our knowledge
  of the origins and early development of CMEs at the Sun and how they
  affect space weather at Earth. A new heliospheric experiment, the Solar
  Mass Ejection Imager, has completed 3 years in orbit and has obtained
  results on the propagation of CMEs through the inner heliosphere
  and their geoeffectiveness. We review key coronal properties of CMEs,
  their source regions, their manifestations in the solar wind, and their
  geoeffectiveness. Halo-like CMEs are of special interest for space
  weather because they suggest the launch of a geoeffective disturbance
  toward Earth. However, not all halo CMEs are equally geoeffective
  and this relationship varies over the solar cycle. Although CMEs are
  involved with the largest storms at all phases of the cycle, recurrent
  features such as interaction regions and high speed wind streams can
  also be geoeffective.

---------------------------------------------------------
Title: Preparing for the International Heliophysical Year (IHY) 2007
Authors: Davila, J. M.; Gopalswamy, N.; Thompson, B. J.
2006ilws.conf..231D    Altcode:
  The International Geophysical Year (IGY) of 1957, a broad-based and
  all-encompassing effort to push the frontiers of geophysics, resulted
  in a tremendous increase of knowledge in space physics, Sun-Earth
  Connection, planetary science and the heliosphere in general. Now, 50
  years later, we have the unique opportunity to advance our knowledge of
  the global heliosphere and its interaction with planetary bodies and
  the interstellar medium through the International Heliophysical Year
  (IHY) in 2007. This will be an international effort, which will raise
  public awareness of space physics.

---------------------------------------------------------
Title: The IHY/United Nations Distributed Observatory Development
    Program
Authors: Haubold, H.; Thompson, B. J.; Al-Naimiy, H.; Davila, J. M.;
   Gopalswamy, N.; Groves, K.; Scherrer, D.
2006cosp...36.3304H    Altcode: 2006cosp.meet.3304H
  A major thrust of the International Heliophysical Year IHY is to
  deploy arrays of small inexpensive instruments such as magnetometers
  radio antennas GPS receivers all-sky cameras etc around the world
  to provide global measurements of ionospheric magnetospheric and
  heliospheric phenomena This program is a collaboration between the IHY
  and the United Nations Basic Space Science Initiative UNBSSI which has
  been dedicated to the IHY through 2009 The small instrument program
  consists of a partnership between instrument providers and instrument
  host countries The lead scientist provides the instrumentation or
  fabrication plans for instruments in the array the host country
  provides manpower facilities and operational support to obtain data
  with the instrument typically at a local university This program has
  been active in deploying instrumentation developing plans for new
  instrumentation and identifying educational opportunities for the host
  nations in association with this program We will discuss the program
  s status significant deployment activities and plans for 2007-2009

---------------------------------------------------------
Title: Geoeffectiveness of CMEs: A simple analysis using halo CMEs
    from SOHO
Authors: Gopalswamy, N.; Yashiro, S.; Akiyama, S.
2006cosp...36.2723G    Altcode: 2006cosp.meet.2723G
  We considered the geoeffectiveness of a set of all halo coronal mass
  Ejections CMEs detected by the Solar and Heliospheric Observatory SOHO
  during 1996-2003 inclusive Since CMEs take 1-4 days to reach Earth we
  chose the minimum Dst value over an interval of 1-5 days after the
  onset of a halo CME Distributions of these Dst values were compared
  for the following subsets of halo CMEs 1 front-side halos whose solar
  sources were within 45 degrees from the central meridian 2 Asymmetric
  halos or limb halos whose sources are front-sided but located beyond
  45 degrees from the central meridian and 3 backside halo CMEs We find
  that the average and median Dst values following the front-side halos
  are at the intense storm level -100 nT those following the asymmetric
  halos are at weak storm level -60 nT and those following the backside
  halos are not indicative of storms Note that we did not eliminate
  moderate storms caused by high speed streams from coronal holes
  When we compiled the minimum Dst values during 1-5 days following
  a set of random days we found that the Dst distribution is nearly
  identical to the case of backside halos This simple analysis clearly
  demonstrates that the front-side halos are highly geoeffective whereas
  the asymmetric halos are marginally geoeffective The backside halo
  CMEs are not geoeffective at all because the CME plasma is unlikely
  to reach Earth from backside CMEs

---------------------------------------------------------
Title: Magnetic Storms Caused by Corotating Solar Wind Streams
Authors: Tsurutani, Bruce T.; McPherron, Robert L.; Gonzalez, Walter
   D.; Lu, Gang; Gopalswamy, Nat; Guarnieri, Fernando L.
2006GMS...167....1T    Altcode:
  Geomagnetic activity at Earth due to corotating high speed solar wind
  streams are reviewed. High density plasma regions in the vicinity
  of the heliospheric current sheet in the slow solar wind impinge
  upon the magnetosphere and create magnetic storm intial phases. Dst
  increases can be higher than those associated with shocks in front of
  interplanetary coronal mass ejections. High speed streams following
  the high density interplanetary plasma interact with the upstream slow
  speed streams and create magnetic field compression regions called
  corotating interaction regions (CIRs). The southward components of
  the typically rapid Bz fluctuations within the CIRs, through sporadic
  magnetic reconnection with the Earth's magnetic fields, lead to
  weak to moderate intensity magnetic storm main phases, typically Dst
  &gt;-100 nT. Some CIRs (without southward component Bz fields) cause no
  perceptible Dst changes at all. The "recovery" phases of CIR-induced
  magnetic storms can last for a few days up to 27 days. The cause of
  these particularly long duration storm "recoveries" is near-continuous
  shallow plasma injections into the magnetosphere. Magnetic reconnection
  associated with the southward component of the Alfvén waves within
  the high speed streams with magnetopause fields is the cause of
  these injections. The auroras during these intervals are continuous
  and global auroral zone features. The AE/AL maxima are not substorms
  or convection bays. Relativistic electrons are accelerated/observed
  during these high speed stream intervals. The electrons first appear
  in the beginning of the lengthy storm "recovery" phases. Geomagnetic
  quiet is due to weak interplanetary magnetic fields with a lack of
  Alfvénic fluctuations. These interplanetary regions generally occur
  in the decay portion of high speed streams.

---------------------------------------------------------
Title: The CME-productivity associated with flares from two ARs
Authors: Akiyama, S.; Gopalswamy, N.; Yashiro, S.
2006cosp...36..556A    Altcode: 2006cosp.meet..556A
  NOAA active region AR 10039 appeared at the east limb on 21 July 2002
  and rotated out of the earthside on 4 August This AR was magnetically
  complex consisting of a spot group with a beta-gamma delta BGD
  configuration from the start It produced 3 X- and 8 M-Class X-ray
  flares during its disk passage NOAA AR 10044 located just to the
  southwest of AR 10039 developed gradually into a BGD configuration
  on 26 July and produced 9 M-class flares We examined the coronal mass
  ejection CME associations rate R of these X-ray flares using data from
  the Large Angle Spectrometric Coronagraph LASCO on board the Solar
  and Heliospheric Observatory SOHO We found the CME-productivity to be
  different between the two ARs AR 10039 was CME-rich with 72 association
  with flares while AR 10044 was CME-poor with an association rate of
  only 13 We also calculated the average velocity and angular width of
  CMEs from the two ARs On the average the CMEs from the CME-rich AR were
  faster 1195 km s and wider 246 deg than the ones from the CME-poor AR
  282 km s and 12 deg We discuss the characteristics of the ARs which
  might have resulted in the observed differences

---------------------------------------------------------
Title: International coordinated efforts for IHY 2007
Authors: Gopalswamy, N.; Davila, J.; Thompson, B.
2006cosp...36.2743G    Altcode: 2006cosp.meet.2743G
  The International Heliophysical Year IHY in 2007 marks the enormous
  progress made since the International Geophysical Year IGY in 1957
  The philosophy behind IHY is similar to that of IGY in studying the
  environment of our habitat except that the scope has increased to the
  physical space extending to the interstellar medium This paper describes
  the international organization of the IHY and planning for a successful
  program in 2007 In particular we describe the national regional and
  global efforts in pooling the resources to address the universal
  processes that govern the solar system and its interaction with the
  surrounding medium The efforts include identifying science questions of
  immediate concern and the data sets needed to address these questions
  The data will be acquired using a truly distributed observatory
  consisting of all the ground and space-based instruments that exist
  today and those to be constructed before 2007 The international planning
  also involves coordinating with the United Nations which through its
  Basic Space Science Initiative is facilitating the participation of the
  developing nations in the IHY program An update of the current status
  of the planning activities at the international level will be presented

---------------------------------------------------------
Title: Anemone structure of AR NOAA 10798 and related geo-effective
    flares and CMEs
Authors: Asai, A.; Ishii, T. T.; Shibata, K.; Gopalswamy, N.
2006cosp...36.2406A    Altcode: 2006cosp.meet.2406A
  We report coronal features of an active region NOAA 10798 This
  active region was located in the middle of a small coronal hole and
  generated 3 M-class flares The flares are associated with high speed
  CMEs which produced a magnetic storm on 2005 August 24 We examined
  the coronal features by using observational data in soft X-rays in
  extreme ultraviolets and in microwaves obtained with GOES SOHO TRACE
  satellites and Nobeyama Radioheliograph

---------------------------------------------------------
Title: The Pre-CME Sun
Authors: Gopalswamy, N.; Mikić, Z.; Maia, D.; Alexander, D.; Cremades,
   H.; Kaufmann, P.; Tripathi, D.; Wang, Y. -M.
2006cme..book..303G    Altcode:
  The coronal mass ejection (CME) phenomenon occurs in closed magnetic
  field regions on the Sun such as active regions, filament regions,
  transequatorial interconnection regions, and complexes involving a
  combination of these. This chapter describes the current knowledge
  on these closed field structures and how they lead to CMEs. After
  describing the specific magnetic structures observed in the CME source
  region, we compare the substructures of CMEs to what is observed before
  eruption. Evolution of the closed magnetic structures in response to
  various photospheric motions over different time scales (convection,
  differential rotation, meridional circulation) somehow leads to the
  eruption. We describe this pre-eruption evolution and attempt to link
  them to the observed features of CMEs. Small-scale energetic signatures
  in the form of electron acceleration (signified by nonthermal radio
  bursts at metric wavelengths) and plasma heating (observed as compact
  soft X-ray brightening) may be indicative of impending CMEs. We survey
  these pre-eruptive energy releases using observations taken before
  and during the eruption of several CMEs. Finally, we discuss how the
  observations can be converted into useful inputs to numerical models
  that can describe the CME initiation.

---------------------------------------------------------
Title: Preface
Authors: Tsurutani, Bruce T.; McPherron, Robert L.; Gonzalez, Walter
   D.; Lu, Gang; Sobral, José Humberto A.; Gopalswamy, Nat
2006GMS...167D...1T    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Solar Influence on the Heliosphere and Earth's Environment:
    Recent Progress and Prospects
Authors: Gopalswamy, N.; Bhattacharyya, A.
2006ilws.conf.....G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The International Heliophysical Year (IHY) 2007
Authors: Davila, J. M.; Thompson, B. J.; Gopalswamy, N.
2006AfrSk..10....4D    Altcode:
  The International Geophysical Year (IGY) of 1957, a broad-based
  and all-encompassing effort to push the frontiers of geophysics,
  resulted in a tremendous increase of knowledge in space physics,
  the Sun-Earth connection, planetary science, and the heliosphere in
  general. Now, fifty years later, we have the unique opportunity to
  advance our knowledge of the global heliosphere and its interaction with
  planetary bodies and the interstellar medium through the International
  Heliophysical Year (IHY) in 2007. This will be an international effort
  which will raise public awareness of space physics. Because of its
  unique geographic position, Africa is well-positioned to play a
  critical role.

---------------------------------------------------------
Title: Microsat and Lunar-Based Imaging of Radio Bursts
Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Demaio,
   L. D.; Bale, S. D.; Hewitt, J.; Kasper, J. C.; Lazarus, A. J.; Howard,
   R. E.; Jones, D. L.; Reiner, M. J.; Weiler, K. W.
2006pre6.conf..491M    Altcode: 2006pre4.conf..491M
  No present or approved spacecraft mission has the capability to
  provide high angular resolution imaging of solar or magnetospheric
  radio bursts or of the celestial sphere at frequencies below the
  ionospheric cutoff. Here, we describe a spacecraft mission to perform
  such imaging in the frequency range ∼30 kHz to 15 MHz. This mission,
  the Solar Imaging Radio Array (SIRA), is solar and exploration-oriented,
  with emphasis on improved understanding and application of radio
  bursts associated with solar energetic particle (SEP) events and
  on tracking shocks and other components of coronal mass ejections
  (CMEs). SIRA will require 12 to 16 micro- satellites to establish
  a sufficient number of baselines. The proposed microsat is 3-axis
  stabilized with body-mounted solar arrays and an articulated, Earth
  pointing high gain antenna. Crossed dipoles and simple radio receivers
  are the detectors for the aperture synthesis imaging. The microsats
  will be located quasi-randomly on a spherical shell, initially of
  ∼10 km diameter. This constellation will likely be placed in a halo
  orbit around L1, which is the preferred location for full-time solar
  observations. We also discuss briefly follow-on missions such as a
  lunar-based radio interferometer with of order 10 000 dipole antennas.

---------------------------------------------------------
Title: The Solar Imaging Radio Array: Space-Based Imaging of Solar,
    Heliospheric, Magnetospheric, and Astrophysical Sources at Frequencies
    below the Ionospheric Cutoff
Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Bale, S. D.;
   Demaio, L. D.; Hewitt, J. N.; Kasper, J. C.; Lazarus, A. J.; Howard,
   R. E.; Jones, D. L.; Reiner, M. J.; Weiler, K. W.
2005ASPC..345..476M    Altcode:
  Solar Imaging Radio Array (SIRA) is a mission concept for space-based,
  interferometric imaging of solar and interplanetary radio emission
  at frequencies below the Earth's ionospheric cutoff. Observing in a
  frequency range of ∼30 kHz to 15 MHz, SIRA will observe the radio
  emission from shocks driven by fast coronal mass ejections (CMEs). The
  radio emissions permit tracking the leading boundaries of CMEs from
  ∼2 R<SUB>s</SUB> to 1 AU. When a CME impacts Earth's magnetosphere,
  the dynamic response will be imaged in the light of magnetospheric
  radio emissions, such as auroral kilometric radiation (AKR), scattered
  on magnetospheric density gradients. The near-term possibility for a
  SIRA mission is based on a NASA MIDEX-class mission, consisting of a
  single constellation of ∼16 microsats located quasi-randomly on a
  spherical shell of ∼10 km diameter. Such a mission is the logical
  next step in space-based solar radio observations, as well as offering
  a unique space weather prediction capability for the NASA Exploration
  Initiative. SIRA will also serve a valuable role as a pathfinder for
  more complex constellation and interferometry missions.

---------------------------------------------------------
Title: Introduction to special section on Solar Coronal Mass Ejections
    and Energetic Particles
Authors: Gopalswamy, Nat; Torsti, J.
2005JGRA..11012S00G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Space-based Radio Imaging at Frequencies below the Ionospheric
    Cutoff with SIRA
Authors: MacDowall, R. J.; Gopalswamy, N.; Kaiser, M. L.; Demaio,
   L. D.; Bale, S. D.; Howard, R. E.; Jones, D. L.; Kasper, J. C.;
   Reiner, M. J.; Weiler, K. W.
2005AAS...207.2308M    Altcode: 2005BAAS...37Q1197M
  No present or approved spacecraft mission has the capability to provide
  high angular resolution imaging of solar or magnetospheric radio
  bursts or of the celestial sphere at frequencies below the ionospheric
  cutoff. In this presentation, we review a MIDEX-class mission to
  perform such imaging in the frequency range 30 kHz to 15 MHz. The
  focus of the mission, the Solar Imaging Radio Array (SIRA), is solar
  and exploration-oriented, with emphasis on improved understanding and
  application of radio bursts associated with solar energetic particle
  (SEP) events and on tracking shocks and other components of coronal
  mass ejections (CMEs). SIRA will require 12 to 16 micro-satellites
  to establish a sufficient number of baselines with separations on the
  order of kilometers. The constellation consists of microsats located
  quasi-randomly on a spherical shell, initially of radius 5 km. The
  baseline microsat is 3-axis stabilized with body-mounted solar arrays
  and an articulated, earth pointing high gain antenna. The constellation
  will likely be placed at L1, which is the preferred location for
  full-time solar observations. Detailed mission science and technology
  goals will be reviewed.

---------------------------------------------------------
Title: Visibility of coronal mass ejections as a function of flare
    location and intensity
Authors: Yashiro, S.; Gopalswamy, N.; Akiyama, S.; Michalek, G.;
   Howard, R. A.
2005JGRA..11012S05Y    Altcode:
  We report the visibility (detection efficiency) of coronal mass
  ejections (CMEs) of the Large Angle Spectrometric Coronagraph (LASCO) on
  board the Solar and Heliospheric Observatory (SOHO). We collected 1301
  X-ray flare events (above C3 level) detected by the GOES satellite and
  examined their CME associations using data from LASCO coronagraphs. The
  CME visibility was examined using the longitudinal variation of
  CME association of X-ray flares, under the assumption that all CMEs
  associated with limb flares are detectable by LASCO. Our findings are
  (1) the CME association rate clearly increased with X-ray flare size
  from 20% for C-class flares (between C3 and C9 levels) to 100% for
  huge flares (above X3 level), (2) all CMEs associated with X-class
  flares were detected by the LASCO coronagraphs, while half (25-67%)
  of CMEs associated with C-class flares were invisible. We examined
  the statistical properties of the flare-associated CMEs and compared
  them by flare size and longitude. CMEs associated with X-class flares
  were significantly faster (median 1556 km/s) and wider (median 244°)
  than those of CMEs associated with disk C-class flares (432 km/s,
  68°). We conclude that all fast and wide CMEs are detectable by LASCO,
  but slow and narrow CMEs may not be visible when the CMEs originate
  from the disk center.

---------------------------------------------------------
Title: Workshop Highlights Progress in Solar-Heliospheric Physics
Authors: Gopalswamy, Nat
2005EOSTr..86..525G    Altcode:
  The Solar, Heliospheric, and Interplanetary Environment (SHINE) group
  is an affiliation of researchers dedicated to promoting an enhanced
  understanding of the processes by which magnetic fields, plasmas,
  and energetic particles are produced near the Sun and propagated
  through the interplanetary medium to Earth and other locations in
  the heliosphere. The group conducted its annual workshop in July to
  discuss recent developments in the study of solar variability and its
  impact on Earth's space environment. One hundred fifty-five scientists,
  including 27 students, participated in the plenary, working group,
  and poster sessions. Student Day activities on 10 July consisted of
  tutorials given by experienced scientists: solar flares and particle
  acceleration (Robert Lin, University of California Berkeley), the
  origin of coronal mass ejections (CMEs) (Spiro Antiochos, Naval
  Research Laboratory, Washington, D.C.), connecting the Sun and
  heliosphere (Thomas Zurbuchen, University of Michigan, Ann Arbor),
  and acceleration and transport of solar energetic particles (SEPs)
  (Christina Cohen, California Institute of Technology, Pasadena). The
  tutorials were followed by student presentations on CMEs near the sun
  and in the interplanetary medium, solar wind, and SEPs.

---------------------------------------------------------
Title: Type II radio bursts and energetic solar eruptions
Authors: Gopalswamy, N.; Aguilar-Rodriguez, E.; Yashiro, S.; Nunes,
   S.; Kaiser, M. L.; Howard, R. A.
2005JGRA..11012S07G    Altcode:
  We report on a study of type II radio bursts from the Wind/WAVES
  experiment in conjunction with white-light coronal mass ejections (CME)
  from the Solar and Heliospheric Observatory (SOHO). The type II bursts
  considered here have emission components in all the spectral domains:
  metric, decameter-hectometric (DH) and kilometric (km), so we refer to
  them as m-to-km type II bursts. CMEs associated with the m-to-km type
  II bursts were more energetic than those associated with bursts in any
  single wavelength regime. CMEs associated with type II bursts confined
  to the metric domain were more energetic (wider and faster) than the
  general population of CMEs but less energetic than CMEs associated
  with DH type II bursts. Thus the CME kinetic energy seems to organize
  the life time of the type II bursts. Contrary to previous results,
  the starting frequency of metric type II bursts with interplanetary
  counterparts seems to be no different from that of type II bursts
  without interplanetary counterparts. We also verified this by showing
  that the average CME height at the onset time of the type II bursts
  is the same for the two metric populations. The majority (78%) of the
  m-to-km type II bursts were associated with solar energetic particle
  (SEP) events. The solar sources of the small fraction of m-to-km
  type II bursts without SEP association were poorly connected to the
  observer near Earth. Finally, we found that the m-to-km type II bursts
  were associated with bigger flares compared to the purely metric type
  II bursts.

---------------------------------------------------------
Title: A universal characteristic of type II radio bursts
Authors: Aguilar-Rodriguez, E.; Gopalswamy, N.; MacDowall, R.; Yashiro,
   S.; Kaiser, M. L.
2005JGRA..11012S08A    Altcode:
  We present a study on the spectral properties of interplanetary
  type II radio bursts observed by the Radio and Plasma Wave (WAVES)
  experiment on board the Wind spacecraft. We investigated the relative
  bandwidth of the type II radio bursts observed by WAVES from 1997 up to
  2003. We obtained three sets of events, based on the frequency domain of
  occurrence: 109 events in the low-frequency domain (30 KHz to 1000 kHz,
  detected by the RAD1 receiver), 216 events in the high-frequency domain
  (1-14 MHz, observed by the RAD2 receiver), and 73 events that spanned
  both domains (RAD1 and RAD2). Statistical results show that the average
  bandwidth-to-frequency ratio (BFR) was 0.28 ± 0.15, 0.26 ± 0.16,
  and 0.32 ± 0.15 for RAD1, RAD2, and RAD1 + RAD2, respectively. We
  compared our results with those obtained for ISEE-3 type II bursts
  and found a difference in the average BFR, which seems to be due to
  a selection effect. The BFR of the WAVES type II bursts is similar
  to that of metric type II bursts reported in published works. This
  suggests that the BFR is a universal characteristic, irrespective of
  the spectral domain. Finally, we also studied the BFR evolution with
  heliocentric distance using white-light observation of the associated
  coronal mass ejections. We found that the BFR remains roughly constant
  in the SOHO/LASCO field of view (i.e., from 2.1 to 32 solar radii),
  while the bandwidth itself decreases.

---------------------------------------------------------
Title: What is Unusual About the 2005 January 20 SEP Event?
Authors: Gopalswamy, N.; Xie, H.; Yashiro, S.; Usoskin, I.
2005AGUFMSH23A0318G    Altcode:
  We report on the solar energetic particle (SEP) event of 2005 January
  20 that had an associated ground level enhancement (GLE). The Solar
  and Heliospheric Observatory (SOHO) spacecraft observed a CME, which
  was among the fastest of cycle 23 CMEs. This event is consistent with
  the results that the GLE-associated CMEs represent the fastest known
  population of CMEs. A metric type II burst started before the proton
  injection time, suggesting that a coronal shock was formed before
  high-energy protons were released at the Sun. These 2005 January 20
  event is consistent with the current paradigm that large SEP events
  originate in CME-driven shocks. We also determined the height of
  the CME at two time marks: the metric type II onset (2.1 Rs) and
  the proton injection time (4.5 Rs). At a height of 4.5 Rs the CME
  should have attained the maximum speed, thus driving the strongest
  shocks. We discuss the estimation of the CME speed given that the
  coronagraph observations were hampered by the SEPs arriving at the SOHO
  spacecraft. We also discuss the arrival of the CME-associated plasma
  and shock at 1 AU. Work supported by NASA/LWS and NSF/SHINE programs.

---------------------------------------------------------
Title: Distributed Instrumentation Deployment During the IHY
Authors: Davila, J. M.; Thompson, B. J.; Gopalswamy, N.
2005AGUFMSM21A0347D    Altcode:
  A major thrust of the International Heliophysical Year (IHY) is to
  deploy arrays of small, inexpensive instruments such as magnetometers,
  radio antennas, GPS receivers, all-sky cameras, etc. around the
  world to provide global measurements of ionospheric and heliospheric
  phenomena. This program is a collaboration between the IHY and the
  United Nations Basic Space Science (UNBSS) program, which has been
  dedicated to the IHY through 2009. The small instrument program is
  envisioned as a partnership between instrument providers, and instrument
  host countries. The lead scientist will provide the instruments (or
  fabrication plans for instruments) in the array; the host country
  will provide manpower, facilities, and operational support to obtain
  data with the instrument typically at a local university. Instrument
  operational support for local scientists, facilities, data acquisition,
  etc will be provided by the host nation.

---------------------------------------------------------
Title: Introduction to violent Sun-Earth connection events of
    October-November 2003
Authors: Gopalswamy, N.; Barbieri, L.; Cliver, E. W.; Lu, G.; Plunkett,
   S. P.; Skoug, R. M.
2005JGRA..110.9S00G    Altcode: 2005JGRA..11009S00G
  The solar-terrestrial events of late October and early November 2003,
  popularly referred to as the Halloween storms, represent the best
  observed cases of extreme space weather activity observed to date and
  have generated research covering multiple aspects of solar eruptions and
  their space weather effects. In the following article, which serves as
  an abstract for this collective research, we present highlights taken
  from 61 of the 74 papers from the Journal of Geophysical Research,
  Geophysical Research Letters, and Space Weather which are linked under
  this special issue. (An overview of the 13 associated papers published
  in Geophysics Research Letters is given in the work of Gopalswamy et
  al. (2005a)).

---------------------------------------------------------
Title: A Study of the Drift Rate of Type II Radio Bursts at Different
    Wavelengths
Authors: Aguilar-Rodriguez, E.; Gopalswamy, N.; MacDowall, R.; Yashiro,
   S.; Kaiser, M. I.
2005ESASP.592..393A    Altcode: 2005soho...16E..65A; 2005ESASP.592E..65A
  No abstract at ADS

---------------------------------------------------------
Title: Coronal mass ejections and other extreme characteristics of
    the 2003 October-November solar eruptions
Authors: Gopalswamy, N.; Yashiro, S.; Liu, Y.; Michalek, G.; Vourlidas,
   A.; Kaiser, M. L.; Howard, R. A.
2005JGRA..110.9S15G    Altcode: 2005JGRA..11009S15G
  Fast coronal mass ejections (CMEs), X-class flares, solar energetic
  particle (SEP) events, and interplanetary shocks were abundantly
  observed during the episode of intense solar activity in late October
  and early November 2003. Most of the 80 CMEs originated from three
  active regions (NOAA ARs 484, 486, and 488). We compare the statistical
  properties of these CMEs with those of the general population of CMEs
  observed during cycle 23. We find that (1) the 2003 October-November
  CMEs were fast and wide on the average and hence were very energetic,
  (2) nearly 20 percent of the ultrafast CMEs (speed ≥2000 km
  s<SUP>-1</SUP>) of cycle 23 occurred during the October-November
  interval, including the fastest CME of the study period (∼2700
  km s<SUP>-1</SUP> on 4 November 2003 at 1954 UT), (3) the rate of
  full-halo CMEs was nearly four times the average rate during cycle 23,
  (4) at least sixteen shocks were observed near the Sun, while eight of
  them were intercepted by spacecraft along the Sun-Earth line, (5) the
  CMEs were highly geoeffective: the resulting geomagnetic storms were
  among the most intense of cycle 23, (6) the CMEs were associated with
  very large SEP events, including the largest event of cycle 23. These
  extreme properties were commensurate with the size and energy of the
  associated active regions. This study suggests that the speed of CMEs
  may not be much higher than ∼3000 km s<SUP>-1</SUP>, consistent with
  the free energy available in active regions. An important practical
  implication of such a speed limit is that the Sun-Earth travel times of
  CME-driven shocks may not be less than ∼0.5 day. Two of the shocks
  arrived at Earth in &lt;24 hours, the first events in ∼30 years and
  only the 14th and 15th documented cases of such events since 1859.

---------------------------------------------------------
Title: Flare-generated shock evolution and geomagnetic storms during
the “Halloween 2003 epoch”: 29 October to 2 November
Authors: Wu, Chin-Chun; Wu, S. T.; Dryer, M.; Fry, C. D.; Berdichevsky,
   D.; Smith, Z.; Detman, T.; Gopalswamy, N.; Skoug, R.; Zurbuchen, T.;
   Smith, C.
2005JGRA..110.9S17W    Altcode: 2005JGRA..11009S17W
  The October/November 2003 ("Halloween 2003") epoch of intense solar
  flares provided an opportunity to test the results of earlier
  parametric 1.5 MHD studies of interacting interplanetary shock
  waves. These preliminary studies used an adaptive numerical grid that
  made it possible to identify products of these interactions. During 28
  October to 2 November 2003, three shocks generated by four solar flares
  were observed at the L1 libration point by ACE/SWEPAM/SWICS/MAG. Two
  very distinct geomagnetic storms, associated with two of these flares
  (X17/4B and X10/2B), rank as two of the largest storms of solar cycle
  23. The purpose of this paper is to present the use of an adaptive
  grid 1.5-dimensional MHD model that is initiated at the solar surface
  to study in detail the three shocks observed at L1 that were generated
  by the four solar flares. Accordingly, four separate pressure pulses,
  at the appropriate times and with different strengths and duration,
  determined via a trial and error procedure, are introduced on the Sun
  to mimic the four flares. The results show that the simulated solar
  wind velocity temporal profiles successfully matched the observations
  at L1. The major objective, to demonstrate the detailed nature of
  interacting shocks and some of their products after origination from
  closely spaced solar events, is achieved. In addition, the MHD model
  is able to suggest the solar sources that are associated with specific
  geomagnetic storms at Earth.

---------------------------------------------------------
Title: Coronal Mass Ejections and Galactic Cosmic-Ray Modulation
Authors: Lara, A.; Gopalswamy, N.; Caballero-López, R. A.; Yashiro,
   S.; Xie, H.; Valdés-Galicia, J. F.
2005ApJ...625..441L    Altcode:
  We present a study of the long-term evolution of coronal mass ejections
  (CMEs) observed by the Large Angle and Spectrometric Coronograph
  (LASCO) on board SOHO during the ascending, maximum, and part of
  the descending phases of solar cycle 23 and their relation with the
  modulation of galactic cosmic-ray (GCR) intensity observed at 1 AU
  by the Climax neutron monitor and IMP-8 spacecraft. We compare the
  long-term GCR modulation with the CME occurrence rate at all, low,
  and high latitudes, as well as the observed CME parameters (width and
  speed). Twenty-seven day averages of CME occurrence rates and CME
  properties from 1996 January to 2003 December are presented in the
  Appendix. The general anticorrelation between GCR intensity and the
  CME rate is relatively high (~-0.88). However, when we divide the CME
  rate into low- and high-latitude rates and compare them with the GCR
  intensity during the ascending phase of solar cycle 23, we find a lower
  anticorrelation between the low-latitude the CME rate and GCR intensity
  (~-0.71) and a very high anticorrelation between the high-latitude
  CME rate and GCR intensity (~-0.94). This suggests that, in general,
  CMEs could cause the decrease in the GCR flux in the inner heliosphere,
  as stated by the global merged interaction region (GMIR) theory. In
  particular, during the ascending phase of cycle 23 (qA&gt;0), this flux
  comes mainly from heliospheric polar regions. Thus, high-latitude CMEs
  may play a central role in the long-term cosmic-ray modulation during
  this phase of the cycle by blocking the polar entrance of GCRs to the
  inner heliosphere. This study supports the scenario in which CMEs, among
  other structures, are the building blocks of GMIRs, although we propose
  that the spherical shells (GMIRs) are closed separately at polar and
  equatorial regions by CMEs of different latitudes. Our results suggest
  that all CME properties show some correlation with the GCR intensity,
  although there is no specific property (width, speed, or a proxy of
  energy) that definitely has a higher correlation with GCR intensity.

---------------------------------------------------------
Title: Statistical Study of Shocks and CMEs Associated With
    Interplanetary Type II Bursts
Authors: Aguilar-Rodriguez, E.; Gopalswamy, N.; MacDowall, R.; Yashiro,
   S.; Kaiser, M. L.
2005AGUSMSH43A..04A    Altcode:
  We present a study of some spectral properties associated with
  interplanetary Type II radio emission. Type II radio bursts are
  signatures of violent eruptions from the Sun that result in shock
  waves propagating through the corona and the interplanetary medium. We
  investigated the relative bandwidth of all the type II bursts observed
  by the Radio and Plasma Wave Experiment (WAVES) on board the Wind
  spacecraft from 1997 up to 2003. We obtained three sets of events,
  based on the frequency domain of occurrence: 109 events in the low
  frequency domain (30 KHz to 1000 kHz detected by the RAD1 receiver),
  216 events in the high frequency domain (1-14 MHz, observed by the RAD2
  receiver), and 73 events that spanned both domains (RAD1 and RAD2). We
  present statistical results for the bandwidth-to-frequency ratio (BFR)
  in the three subsets as well as a comparision of our results with the
  Type II solar radio bursts observed by ISEE-3 radio experiment, which
  is similar to WAVES/RAD1. We analyzed the bandwidth and BFR evolution
  with the heliocentric distance as well as an analysis of drift rate
  magnitude of type II radio bursts and its starting frequency. We also
  present some properties of shocks and coronal mass ejections associated
  with interplanetary type II bursts. This work is partially supported
  by NSF/SHINE (ATM 0204588)

---------------------------------------------------------
Title: Sun-Earth Propagation Time of CMEs Originated at different
    Helio Longitudes
Authors: Lara, A.; Gopalswamy, N.; Xie, H.; Gonzalez-Esparza, A.
2005AGUSMSH53A..10L    Altcode:
  We present a study of the transport of coronal mass ejections
  (CMEs) in the interplanetary medium and the probability that they,
  or the associated shocks, reach the Earth surroundings when they are
  ejected in different Helio-longitudes. To reach this goal we choose the
  CME events associated with the active region 0486 which crosses the
  solar disk during October - November 2003 and produced several CMEs
  during its crossing from East to West limb. We measured and analyzed
  the speed profile of each event, we found that the speed profile of
  halos and partial-halo CMEs are very symmetric and an elliptical model
  seems to fit the profiles very well. Using a cone model we determine
  the space direction of CMEs and then, the most probable speed in the
  Sun-Earth direction. Using these speeds, we applied the CME travel
  time empirical model to determine the near Earth arrival times of both
  interplanetary CME and related shock. We found that the difference
  between the predicted and observed arrival times increase with the
  Helio-longitude of the CME. To help in the identification of CME -
  1 AU shocks and to validate the empirical model, we use 2D numerical
  simulations of the events.

---------------------------------------------------------
Title: Solar source of the largest geomagnetic storm of cycle 23
Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Xie, H.; Lepping,
   R. P.; Howard, R. A.
2005GeoRL..3212S09G    Altcode:
  The largest geomagnetic storm of solar cycle 23 occurred on 2003
  November 20 with a Dst index of -472 nT, due to a coronal mass ejection
  (CME) from active region 0501. The CME near the Sun had a sky-plane
  speed of ~1660 km/s, but the associated magnetic cloud (MC) arrived
  with a speed of only 730 km/s. The MC at 1 AU (ACE Observations) had
  a high magnetic field (~56 nT) and high inclination to the ecliptic
  plane. The southward component of the MC's magnetic field was made
  up almost entirely of its axial field because of its east-south-west
  (ESW) chirality. We suggest that the southward pointing strong axial
  field of the MC reconnected with Earth's front-side magnetic field,
  resulting in the largest storm of the solar cycle 23.

---------------------------------------------------------
Title: Putting the Rubber to the Road: The Whos, Whys and Hows of
    the International Heliophysical Year 2007
Authors: Thompson, B. J.; Davila, J. M.; Drobnes, E.; Gopalswamy,
   N.; Wesenberg, R. P.
2005AGUSM.U23A..07T    Altcode:
  In 1957 a program of international research, inspired by the
  International Polar Years of 1882 and 1932, was organized as the
  International Geophysical Year (IGY) to study global phenomena
  of the Earth and geospace. Fifty years later, the world's science
  community will again come together for international programs of
  scientific collaboration: the International Heliophysical Year
  (IHY), the electronic Geophysical Year (eGY), and the International
  Polar Year (IPY) 2007. This time, research will extend out into the
  heliosphere to focus on solar-terrestrial-planetary interactions. The
  ambitious plans for the IHY, eGY and IPY incorporate the activities
  of scientists in 191 nations, the "IGY Gold" Historical Preservation
  initiative, a series of coordinated campaigns involving more than
  100 instruments and models, education and public outreach programs,
  a developing nations instrument development program, and opportunities
  for supported research worldwide. The presentation will focus on the
  efforts and operations which will make these activities possible.

---------------------------------------------------------
Title: Improved Empirical CME Arrival Time Model Via Cone Model
Authors: Xie, H.; Gopalswamy, N.; Ofman, L.; Michalek, G.; Lara, A.;
   Yashiro, S.
2005AGUSMSH53A..09X    Altcode:
  In this study, we compare the results obtained from two cone models
  and carry out the statistical study of the distribution of the actual
  size and space speed of Coronal Mass Ejections (CMEs). We improved
  the existing empirical CME arrival (ECA) model, based on previously
  developed empirical models and provided the prediction of CME transit
  time from the Sun to the Earth. The previous ECA model was in good
  agreement with the observations for high-speed CMEs. However, the
  agreement was not as good for low-speed events. One of possible reasons
  may be due to errors caused by the significant scatter of CME projection
  speeds in low projected-speed events. Using the cone models we reduced
  the errors and improved the accuracy of the ECA model by applying the
  cone models to halo CMEs erupted from near disk center of the Sun
  (within &lt; 30 deg.) to determine the actual speed. We found that
  both cone models provide similar improved accuracy for the arrival time.

---------------------------------------------------------
Title: Photospheric sources of very fast coronal mass ejections
Authors: Yurchyshyn, V.; Yashiro, S.; Gopalswamy, N.
2005AGUSMSH51C..04Y    Altcode:
  We identified photospheric sources for 39 very fast (v &gt; 1100
  km/s) front-side coronal mass ejections that erupted between 1999 and
  2001. For our study we used data on CMEs and their sources provided
  by the CME Catalog, SOHO spacecraft (LASCO, EIT, MDI), Big Bear Solar
  Observatory (Halpha, magnetograms), Mount Wilson Observatory (sunspot
  drawings) and Joint USAF/NOAA active region summary. Our results are
  as follows. We distinguished three different groups of active regions
  which are responsible for very fast CMEs: 1) Complex delta spots (21
  events). This group of active regions is characterized by the presence
  of at least two large opposite polarity sunspots located close to
  each other. 2) Simple delta spots (8 events). A typical configuration
  of this type consists of one large twisted tadpole-shaped sunspot,
  surrounded by many small satellite-sunspots. 3) Extended magnetic
  regions, which consist of two adjacent decaying active regions or a
  new active region emerging inside a decaying active region.

---------------------------------------------------------
Title: Estimation of Projection Effect of CMEs from the Onset Time
    of the Shock-Associated Type III Radio Burst
Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S.
2005AcA....55..151M    Altcode:
  We present a new possibility to estimate the projection effects
  on coronal mass ejection (CME) measurements. It is well known
  that coronagraphic observations of CMEs are subject to projection
  effects. Fortunately, the WIND/WAVES observations of type III radio
  bursts associated with shock waves are free from projection effects. We
  assume that (1) high energy electrons are produced at the shock front
  ahead of the CME, and (2) the radio burst starts when the shock reaches
  open field lines (approx 3 R_odot). In other words, the onset time
  of the radio burst corresponds to the time when the CME leading edge
  reaches 3 R_odot. The difference between the onset times of CMEs and
  radio bursts should be strongly correlated with the position of CMEs
  on the Sun. This correlation seems to be strongly dependent on solar
  activity. Using particular linear fits on the scatter plots, we can
  determine the source location of CMEs and tell how much the projection
  effect can really affect CME measurements.

---------------------------------------------------------
Title: Introduction to the special section: Violent Sun-Earth
    connection events of October-November 2003
Authors: Gopalswamy, N.; Barbieri, L.; Lu, G.; Plunkett, S. P.; Skoug,
   R. M.
2005GeoRL..32.3S01G    Altcode: 2005GeoRL..3203S01G
  During 2003 October and November, a series of solar eruptions
  occurred from three solar active regions. Some of these eruptions were
  extreme in terms of their origin (source properties) and heliospheric
  consequences. This paper summarizes the first results of the analysis
  of these violent Sun-Earth connection events.

---------------------------------------------------------
Title: CMEs and Long-Lived Geomagnetic Storms: A Case Study
Authors: Xie, H.; Gopalswamy, N.; Manoharan, P. K.; Yashiro, S.;
   Lara, A.; Lepri, S.
2005IAUS..226..475X    Altcode:
  We studied the relationship between successive coronal mass ejections
  (CMEs) and a long-lived geomagnetic storm (LLGMS) by examining the 1998
  May 4 event. Five successive CMEs from the same active region and four
  interplanetary shocks were found to be associated with this LLGMS. We
  investigated the effect of successive and interacting CMEs on the LLGMS.

---------------------------------------------------------
Title: An empirical model to predict the 1-AU arrival of
    interplanetary shocks
Authors: Gopalswamy, N.; Lara, A.; Manoharan, P. K.; Howard, R. A.
2005AdSpR..36.2289G    Altcode:
  We extend the empirical coronal mass ejection (CME) arrival model of
  Gopalswamy et al. [Gopalswamy, N. et al. Predicting the 1-AU arrival
  times of coronal mass ejections, J. Geophys. Res. 106, 29207, 2001]
  to predict the 1-AU arrival of interplanetary (IP) shocks. A set of
  29 IP shocks and the associated magnetic clouds observed by the Wind
  spacecraft are used for this study. The primary input to this empirical
  shock arrival model is the initial speed of white-light CMEs obtained
  using coronagraphs. We use the gas dynamic piston-shock relationship
  to derive the ESA model which provides a simple means of obtaining the
  1-AU speed and arrival times of interplanetary shocks using CME speeds.

---------------------------------------------------------
Title: CME Interaction and the Intensity of Solar Energetic Particle
    Events
Authors: Gopalswamy, N.; Yashiro, S.; Krucker, S.; Howard, R. A.
2005IAUS..226..367G    Altcode:
  Large Solar Energetic Particles (SEPs) are closely associated with
  coronal mass ejections (CMEs). The significant correlation observed
  between SEP intensity and CME speed has been considered as the evidence
  for such a close connection. The recent finding that SEP events with
  preceding wide CMEs are likely to have higher intensities compared to
  those without was attributed to the interaction of the CME-driven shocks
  with the preceding CMEs or with their aftermath. It is also possible
  that the intensity of SEPs may also be affected by the properties
  of the solar source region. In this study, we found that the active
  region area has no relation with the SEP intensity and CME speed,
  thus supporting the importance of CME interaction. However, there is a
  significant correlation between flare size and the active region area,
  which probably reflects the spatial scale of the flare phenomenon as
  compared to that of the CME-driven shock.

---------------------------------------------------------
Title: Statistical Distributions of Speeds of Coronal Mass Ejections
Authors: Yurchyshyn, V.; Yashiro, S.; Abramenko, V.; Wang, H.;
   Gopalswamy, N.
2005ApJ...619..599Y    Altcode:
  We studied the distribution of plane-of-sky speeds determined for
  4315 coronal mass ejections (CMEs) detected by the Large Angle and
  Spectrometric Coronagraph Experiment on board the Solar and Heliospheric
  Observatory (SOHO LASCO). We found that the speed distributions
  for accelerating and decelerating events are nearly identical and
  to a good approximation they can be fitted with a single lognormal
  distribution. This finding implies that, statistically, there is no
  physical distinction between the accelerating and the decelerating
  events. The lognormal distribution of the CME speeds suggests that
  the same driving mechanism of a nonlinear nature is acting in both
  slow and fast dynamical types of CMEs.

---------------------------------------------------------
Title: Coronal Mass Ejections and Ground Level Enhancements
Authors: Gopalswamy, N.; Xie, H.; Yashiro, S.; Usoskin, I.
2005ICRC....1..169G    Altcode: 2005ICRC...29a.169G
  No abstract at ADS

---------------------------------------------------------
Title: Solar Imaging Radio Array (SIRA): a multispacecraft mission
Authors: MacDowall, R. J.; Bale, S. D.; Demaio, L.; Gopalswamy, N.;
   Jones, D. L.; Kaiser, M. L.; Kasper, J. C.; Reiner, M. J.; Weiler,
   K. W.
2005SPIE.5659..284M    Altcode:
  The Solar Imaging Radio Array (SIRA) is a mission to perform
  aperture synthesis imaging of low frequency solar, magnetospheric,
  and astrophysical radio bursts. The primary science targets are
  coronal mass ejections (CMEs), which drive shock waves that may
  produce radio emission. A space-based interferometer is required,
  because the frequencies of observation (&lt;15 MHz) are cutoff by the
  ionosphere. SIRA will require a 12 to 16 microsatellite constellation
  to establish a sufficient number of baselines with separations on the
  order of kilometers. The microsats will be located quasi-randomly on
  a spherical shell, initially of diameter 10 km or less. The baseline
  microsat, as presented here, is 3-axis stabilized with a body-mounted,
  earth-directed high gain antenna and an articulated solar array;
  this design was developed by the Integrated Mission Design Center
  (IMDC) at NASA Goddard Space Flight Center (GSFC). A retrograde orbit
  at a distance of ~500,000 km from Earth was selected as the preferred
  orbit because the 8 Mbps downlink requirement is easy to meet, while
  keeping the constellation sufficiently distant from terrestrial radio
  interference. Also, the retrograde orbit permits imaging of terrestrial
  magnetospheric radio sources from varied perspectives. The SIRA mission
  serves as a pathfinder for space-based satellite constellations and for
  spacecraft interferometry at shorter wavelengths. It will be proposed
  to the NASA MIDEX proposal opportunity in mid-2005.

---------------------------------------------------------
Title: The Solar Imaging Radio Array (SIRA) Mission
Authors: Jones, D. L.; MacDowall, R.; Gopalswamy, N.; Kaiser, M.;
   Reiner, M.; Demaio, L.; Weiler, K.; Kasper, J.; Bale, S.; Howard, R.
2004AAS...205.1012J    Altcode: 2004BAAS...36.1351J
  The Solar Imaging Radio Array will be proposed to NASA as a Medium
  Explorer (MIDEX) mission by a team of investigators at GSFC, JPL, NRL,
  MIT, and UC Berkeley. The main science goal of the mission is imaging
  and tracking of solar radio bursts, particularly those associated with
  coronal mass ejections, and understanding their evolution and influence
  on Earth's magnetosphere. Related goals are mapping the 3-dimensional
  morphology of the interplanetary magnetic field and improving the
  prediction of geomagnetic storms. A number of topics in galactic
  and extragalactic astrophysics will also be addressed by SIRA. The
  mission concept is a free-flying array of about 16 small, inexpensive
  satellites forming an aperture synthesis interferometer in space. By
  observing from above the ionosphere, and far from terrestrial radio
  interference, SIRA will cover frequencies between a few tens of kHz up
  to 15 MHz. This wide spectral window is essentially unexplored with
  high angular resolution. <P />Part of this work is being carried out
  at the Jet Propulsion Laboratory, California Institute of Technology,
  under contract with the National Aeronautics and Space Administration.

---------------------------------------------------------
Title: Intensity variation of large solar energetic particle events
    associated with coronal mass ejections
Authors: Gopalswamy, N.; Yashiro, S.; Krucker, S.; Stenborg, G.;
   Howard, R. A.
2004JGRA..10912105G    Altcode:
  We studied the coronal mass ejections (CMEs) and flares associated
  with large solar energetic particle (SEP) events of solar cycle 23
  (1996-2002) in order to determine what property of the solar eruptions
  might order the SEP intensity. The SEP events were divided into three
  groups: (1) events in which the primary CME was preceded by one or more
  wide CMEs from the same solar source, (2) events with no such preceding
  CMEs, and (3) events in which the primary CME might have interacted
  with a streamer or with a nearby halo CME. The SEP intensities are
  distinct for groups 1 and 2 although the CME properties were nearly
  identical. Group 3 was similar to group 1. The primary findings of this
  study are as follows: (1) Higher SEP intensity results whenever a CME
  is preceded by another wide CME from the same source region. (2) The
  average flare size was also larger for high-intensity SEP events. (3)
  The intensity of SEP events with preceding CMEs showed a tighter
  correlation with CME speed. The extent of scatter in the CME speed
  versus SEP intensity plots was reduced when various subgroups were
  considered separately. (4) The intensities of energetic electrons were
  better correlated with flare size than with CME speed. (5) The SEP
  intensity showed poor correlation with the flare size, except for group
  3 events. Since only a third of the events did not have preceding CMEs,
  we conclude that the majority of SEP producing CMEs propagate through
  the near-Sun interplanetary medium severely disturbed and distorted by
  the preceding CMEs. Furthermore, the preceding CMEs are faster and wider
  on the average, so they may provide seed particles for CME-driven shocks
  that follow. Therefore we conclude that the differing intensities of
  SEP events in the two groups may not have resulted due to the inherent
  properties of the CMEs. The presence of preceding CMEs seems to be the
  discriminating characteristic of the high- and low-intensity SEP events.

---------------------------------------------------------
Title: Improved Empirical CME Arrival Time Prediction Model
Authors: Xie, H.; Gopalswamy, N.; Lara, A.; Yashiro, S.
2004AGUFMSH53B0324X    Altcode:
  We have successfully developed an innovative analytical method
  to determine the angular width and propagation orientation of Halo
  Coronal Mass Ejections (Xie et al. 2003). We will apply this new method
  to improve the existing empirical space weather forecasting models
  (e.g., Gopalswamy et al., 2001). Gopalswamy et al. (2001) presented an
  empirical model to provide the predication of CME transit time from the
  Sun to the Earth. The model is in good agreement with the observations
  for high-speed CMEs. However, the agreement is not good for low-speed
  events. One of possible reasons may be due to errors caused by the
  significant scatter of CME prjection speeds used in the model. Using
  our new method can determine the actual speed of CMEs and thus reduce
  the errors and improve the model.

---------------------------------------------------------
Title: Association of Coronal Mass Ejections and Type II Radio Bursts
    with Impulsive Solar Energetic Particle Events
Authors: Yashiro, S.; Gopalswamy, N.; Cliver, E. W.; Reames, D. V.;
   Kaiser, M. L.; Howard, R. A.
2004ASPC..325..401Y    Altcode:
  We report the association of impulsive solar energetic particle (SEP)
  events with coronal mass ejections (CMEs) and metric type II radio
  bursts. We identified 38 impulsive SEP events using the WIND/EPACT
  instrument and their CME association was investigated using white
  light data from SOHO/LASCO. We found that (1) at least ∼ 28--39 % of
  impulsive SEP events were associated with CMEs, (2) only 8--13 % were
  associated with metric type II radio bursts. The statistical properties
  of the associated CMEs were investigated and compared with those of
  general CMEs and CMEs associated with large gradual SEP events. The
  CMEs associated with impulsive SEP events were significantly slower
  (median speed of 613 kmps) and narrower (49 deg) than those of CMEs
  associated with large gradual SEP events (1336 kmps, 360 deg), but
  faster than the general CMEs (408 kmps).

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Title: Brightness Characteristics of Halo CMEs
Authors: Lara, A.; Gopalswamy, N.; Michalek, G.; Xie, H.; Yashiro, S.
2004AGUFMSH53B0316L    Altcode:
  It is generally accepted that halo Coronal Mass Ejections (CMEs)
  are regular, low latitude, CMEs traveling towards (or away FROM)
  the observer. The association between halo CMEs and solar energetic
  particles events (SEPs) and Type II bursts is higher compared to regular
  CMEs. Halo CMEs are observed up to large heliocentric distances as
  compared to the regular CMEs. This is somewhat contradictory to the
  theory of Thomson scattering because the visibility conditions for
  halo CMEs are rather poor, assuming that the longitudinal widths of
  halo CMEs are the similar to those of regular CMEs. In this paper, we
  present some observational characteristics of halo CMEs, such as high
  brightness at large distances and symmetry in the velocity space. The
  CMEs were observed by the Solar and Heliospheric Observatory (SOHO)
  mission's Large Angle and Spectrometric Coronagraph (LASCO). We also
  present a possible model that explains the apparent contradiction

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Title: Radio-quiet Fast Coronal Mass Ejections
Authors: Gopalswamy, N.; Aguilar-Rodriguez, E.; Kaiser, M. L.; Howard,
   R. A.
2004AGUFMSH23A..05G    Altcode:
  Coronal mass ejections (CMEs) drive shocks in the interplanetary
  medium that produce type II radio emission. These CMEs are faster and
  wider on the average, than the general population of CMEs. However,
  when we start from fast (speed &gt; 900 km/s) and wide (angular
  width &gt; 60 degrees), more than half of them are not associated
  with radio bursts. In order to understand why these CMEs are radio
  quiet, we collected all the fast and wide (FW) CMEs detected by the
  Solar and Heliospheric Observatory (SOHO) mission's Large Angle and
  Spectrometric Coronagraph (LASCO) and isolated those without associated
  type II radio bursts. The radio bursts were identified in the dynamic
  spectra of the Radio and Plasma Wave (WAVES) Experiment on board the
  Wind spacecraft. We also checked the list against metric type II radio
  bursts reported in Solar Geophysical Data and isolated those without
  any radio emission. This exercise resulted in about 140 radio-quiet FW
  CMEs. We identified the source regions of these CMEs using the Solar
  Geophysical Data listings, cross-checked against the eruption regions
  in the SOHO/EIT movies. We explored a number of possibilities for the
  radio-quietness: (i) Source region being too far behind the limb, (ii)
  flare size, (iii) brightness of the CME, and (iv) the density of the
  ambient medium. We suggest that a combination of CME energy and the
  Alfven speed profile of the ambient medium is primarily responsible
  for the radio-quietness of these FW CMEs.

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Title: Solar Imaging Radio Array (SIRA): Imaging solar,
    magnetospheric, and astrophysical sources at &lt; 15 MHz
Authors: Howard, R.; MacDowall, R.; Gopalswamy, N.; Kaiser, M. L.;
   Reiner, M. J.; Bale, S.; Jones, D.; Kasper, J.; Weiler, K.
2004DPS....36.1424H    Altcode: 2004BAAS...36Q1097H
  The Solar Imaging Radio Array (SIRA) is a mission to perform
  aperture synthesis imaging of low frequency solar, magnetospheric, and
  astrophysical radio bursts. The primary science targets are coronal mass
  ejections (CMEs), which drive radio emission producing shock waves. A
  space-based interferometer is required, because the frequencies of
  observation (&lt;15 MHz) do not penetrate the ionosphere. As such,
  the SIRA mission serves as a lower frequency counterpart to LWA, LOFAR,
  and similar ground-based radio imaging arrays. SIRA will require 12 to
  16 microsatellites to establish a sufficient number of baselines with
  separations on the order of kilometers. The microsat constellation
  consists of microsats located quasi-randomly on a spherical shell,
  initially of radius 5 km or less. The baseline microsat is 3-axis
  stabilized with body-mounted solar arrays and an articulated, earth
  pointing high gain antenna. A retrograde orbit at 500,000 km from Earth
  was selected as the preferred orbit because it reduces the downlink
  requirement while keeping the microsats sufficiently distant from
  terrestrial radio interference. Also, the retrograde orbit permits
  imaging of terrestrial magnetospheric radio sources from varied
  perspectives. The SIRA mission serves as a pathfinder for space-based
  satellite constellations and for spacecraft interferometry at shorter
  wavelengths. It will be proposed to the NASA MIDEX proposal opportunity
  in mid-2005.

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Title: Recent advances in the long-wavelength radio physics of the Sun
Authors: Gopalswamy, N.
2004P&SS...52.1399G    Altcode:
  Solar radio bursts at long wavelengths provide information on solar
  disturbances such as coronal mass ejections (CMEs) and shocks at the
  moment of their departure from the Sun. The radio bursts also provide
  information on the physical properties (density, temperature and
  magnetic field) of the medium that supports the propagation of the
  disturbances with a valuable cross-check from direct imaging of the
  quiet outer corona. The primary objective of this paper is to review
  some of the past results and highlight recent results obtained from
  long-wavelength observations. In particular, the discussion will
  focus on radio phenomena occurring in the outer corona and beyond
  in relation to those observed in white light. Radio emission from
  nonthermal electrons confined to closed and open magnetic structures
  and in large-scale shock fronts will be discussed with particular
  emphasis on its relevance to solar eruptions. Solar cycle variation of
  the occurrence rate of shock-related radio bursts will be discussed
  in comparison with that of interplanetary shocks and solar proton
  events. Finally, case studies describing the newly-discovered radio
  signatures of interacting CMEs will be presented.

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Title: A Global Picture of CMEs in the Inner Heliosphere
Authors: Gopalswamy, N.
2004ASSL..317..201G    Altcode: 2004shis.conf..201G
  No abstract at ADS

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Title: Energy partition in two solar flare/CME events
Authors: Emslie, A. G.; Kucharek, H.; Dennis, B. R.; Gopalswamy, N.;
   Holman, G. D.; Share, G. H.; Vourlidas, A.; Forbes, T. G.; Gallagher,
   P. T.; Mason, G. M.; Metcalf, T. R.; Mewaldt, R. A.; Murphy, R. J.;
   Schwartz, R. A.; Zurbuchen, T. H.
2004JGRA..10910104E    Altcode:
  Using coordinated observations from instruments on the Advanced
  Composition Explorer (ACE), the Solar and Heliospheric Observatory
  (SOHO), and the Ramaty High Energy Solar Spectroscopic Imager (RHESSI),
  we have evaluated the energetics of two well-observed flare/CME events
  on 21 April 2002 and 23 July 2002. For each event, we have estimated
  the energy contents (and the likely uncertainties) of (1) the coronal
  mass ejection, (2) the thermal plasma at the Sun, (3) the hard X-ray
  producing accelerated electrons, (4) the gamma-ray producing ions,
  and (5) the solar energetic particles. The results are assimilated
  and discussed relative to the probable amount of nonpotential magnetic
  energy available in a large active region.

---------------------------------------------------------
Title: Interplanetary Radio Bursts
Authors: Gopalswamy, N.
2004ASSL..314..305G    Altcode:
  Nonthermal radio bursts in the interplanetary medium indicate
  the far-reaching effect of solar eruptions that inject energetic
  particles, plasmas and shock waves into the inner heliosphere. More
  than half a century of ground-based observations and subsequent
  space-based observations exist on this phenomena. In this paper, I
  summarize the understanding we have gained on the type III and type
  II radio bursts, which are indicative of electron beams and shocks,
  respectively. Observations in the new radio window (1-14 MHz) from
  Wind/WAVES have not only confirmed previous results, but also led to
  a number of new discoveries. Availability of simultaneous white light
  (SOHO) and radio (Wind) observations from the same spatial domain in
  the near-Sun IP medium is largely responsible for these discoveries on
  the IP propagation of CMEs, so this paper discusses radio bursts in
  the context of white light observations. After exploring the origin
  of normal, complex and storm type III bursts, I discuss the type II
  bursts and their relation to coronal mass ejections. Finally I discuss
  some of the recent developments on IP radio emission.

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Title: Kinematics of coronal mass ejections between 2 and 30 solar
    radii. What can be learned about forces governing the eruption?
Authors: Vršnak, B.; Ruždjak, D.; Sudar, D.; Gopalswamy, N.
2004A&A...423..717V    Altcode:
  Kinematics of more than 5000 coronal mass ejections (CMEs)
  measured in the distance range 2-30 solar radii is investigated. A
  distinct anticorrelation between the acceleration, a, and the
  velocity, v, is found. In the linear form, it can be represented
  as a=-k<SUB>1</SUB>(v-v<SUB>0</SUB>), where v<SUB>0</SUB>=400 km
  s<SUP>-1</SUP>, i.e., most of CMEs faster than 400 km s<SUP>-1</SUP>
  decelerate, whereas slower ones generally accelerate. After grouping
  CMEs into the width and mean-distance bins, it was found that the
  slope k<SUB>1</SUB> depends on these two parameters: k<SUB>1</SUB>
  is smaller for CMEs of larger width and mean-distance. Furthermore,
  the obtained CME subsets show distinct quadratic-form correlations,
  of the form a= -k<SUB>2</SUB> (v-v<SUB>0</SUB>)| v-v<SUB>0</SUB>|. The
  value of k<SUB>2</SUB> decreases with increasing distance and width,
  whereas v<SUB>0</SUB> increases with the distance and is systematically
  larger than the slow solar wind speed by 100-200 km s<SUP>-1</SUP>. The
  acceleration-velocity relationship is interpreted as a consequence of
  the aerodynamic drag. The excess of v<SUB>0</SUB> over the solar wind
  speed is explained assuming that in a certain fraction of events the
  propelling force is still acting in the considered distance range. In
  most events the inferred propelling force acceleration at 10 solar radii
  ranges between a<SUB>L</SUB>=0 and 10 m s<SUP>-2</SUP>, being on average
  smaller at larger distances. However, there are also events that show
  a<SUB>L</SUB>&gt;50 m s<SUP>-2</SUP>, as well as events indicating
  a<SUB>L</SUB>&lt;0. Implications for the interplanetary motion of
  CMEs are discussed, emphasizing the prediction of the 1 a.u. arrival
  time. <P />Appendices A and B are only available in electronic form
  at http://www.edpsciences.org

---------------------------------------------------------
Title: Arrival time of halo coronal mass ejections in the vicinity
    of the Earth
Authors: Michałek, G.; Gopalswamy, N.; Lara, A.; Manoharan, P. K.
2004A&A...423..729M    Altcode:
  We describe an empirical model to predict the 1-AU arrival time of
  halo CMEs. This model is based on the effective acceleration described
  by Gopalswamy et al. (\cite{Gopalswamy00}a, Geophys. Res. Lett., 27,
  145). We verify the Helios/Pioneer Venus Orbiter(PVO) estimation of the
  effective acceleration profile (Gopalswamy et al. \cite{Gopalswamy01}a,
  J. Geophys. Res., 106, 29207) by considering all full halo CMEs recorded
  by SOHO/LASCO coronagraphs until the end of 2002. In comparison with
  previous studies, the present work includes CMEs of a wider range of
  initial velocities. To improve the accuracy of prediction, we propose to
  introduce the effective acceleration from two groups of CMEs only, which
  are expected to have no acceleration cessation at any place between
  the Sun and Earth. In addition, we consider acceleration cessation
  distance dependent on initial velocities of a given event CME. For a
  detailed analysis of this model, we examine projected sky-plane and
  space speeds (Michałek et al. \cite{Michalek03}, ApJ, 584, 472) of
  CMEs. We show that a correct acceleration profile is crucial for the
  estimation of 1 AU arrival time of halo CMEs. We estimate that the CME
  arrival times can be predicted with an average error of 9 and 11 h for
  space and sky-plane initial velocities, respectively. <P />Table 1 is
  only available in electronic form at <P />http://www.edpsciences.org

---------------------------------------------------------
Title: A catalog of white light coronal mass ejections observed by
    the SOHO spacecraft
Authors: Yashiro, S.; Gopalswamy, N.; Michalek, G.; St. Cyr, O. C.;
   Plunkett, S. P.; Rich, N. B.; Howard, R. A.
2004JGRA..109.7105Y    Altcode:
  The Solar and Heliospheric Observatory (SOHO) mission's white light
  coronagraphs have observed nearly 7000 coronal mass ejections (CMEs)
  between 1996 and 2002. We have documented the measured properties of
  all these CMEs in an online catalog. We describe this catalog and
  present a summary of the statistical properties of the CMEs. The
  primary measurements made on each CME are the apparent central
  position angle, the angular width in the sky plane, and the height
  (heliocentric distance) as a function of time. The height-time
  measurements are then fitted to first- and second-order polynomials
  to derive the average apparent speed and acceleration of the CMEs. The
  statistical properties of CMEs are (1) the average width of normal CMEs
  (20° &lt; width ≤ 120°) increased from 47° (1996; solar minimum)
  to 61° (1999; early phase of solar maximum) and then decreased to
  53° (2002; late phase of solar maximum), (2) CMEs were detected
  around the equatorial region during solar minimum, while during solar
  maximum CMEs appear at all latitudes, (3) the average apparent speed
  of CMEs increases from 300 km s<SUP>-1</SUP> (solar minimum) to 500
  km s<SUP>-1</SUP> (solar maximum), (4) the average apparent speed
  of halo CMEs (957 km s<SUP>-1</SUP>) is twice of that of normal CMEs
  (428 km s<SUP>-1</SUP>), and (5) most of the slow CMEs (V ≤ 250 km
  s<SUP>-1</SUP>) show acceleration while most of the fast CMEs (V &gt;
  900 km s<SUP>-1</SUP>) show deceleration. Solar cycle variation and
  statistical properties of CMEs are revealed with greater clarity in
  this study as compared with previous studies. Implications of our
  findings for CME models are discussed.

---------------------------------------------------------
Title: Influence of coronal mass ejection interaction on propagation
    of interplanetary shocks
Authors: Manoharan, P. K.; Gopalswamy, N.; Yashiro, S.; Lara, A.;
   Michalek, G.; Howard, R. A.
2004JGRA..109.6109M    Altcode:
  We studied 91 interplanetary (IP) shocks associated with coronal mass
  ejections (CMEs) originating within about ±30° in longitude and
  latitude from the center of the Sun during 1997-2002. These CMEs cover
  a wide range of initial speeds of about 120 to 2400 kms<SUP>-1</SUP>
  and they also include a special population of 25 interacting CMEs. This
  study provides the characteristics of propagation effects of more number
  of high-speed CMEs (V<SUB>CME</SUB> &gt; 1500 kms<SUP>-1</SUP>) than the
  data used in earlier studies. It enables to extend the shock-arrival
  prediction model to high-speed CMEs. The results on comparison
  of IP shock speed and transit time at 1 AU suggest that the shock
  transit time is not controlled by its final speed but is primarily
  determined by the initial speed of the CME and effects encountered
  by it during the propagation. It is found that the CME interaction
  tends to slow the shock and associated CME. The deviations of shock
  arrival times from the empirical model are considerably large for slow
  (V<SUB>CME</SUB> &lt; 300 kms<SUP>-1</SUP>) and fast (V<SUB>CME</SUB>
  &gt; 800 kms<SUP>-1</SUP>) CMEs. Results show that the slow and fast
  CMEs experience stronger effective acceleration.

---------------------------------------------------------
Title: Coronal Mass Ejections When the Sun Went Wild
Authors: Gopalswamy, N.; Yashiro, S.; Vourlidas, A.; Lara, A.;
   Stenborg, G.; Kaiser, M. L.; Howard, R. A.
2004AAS...204.4709G    Altcode: 2004BAAS...36..738G
  The Large Angle and Spectrometric Coronagraph (LASCO) on board SOHO
  detected more than five dozen CMEs from three active regions (NOAA ARs
  0484, 0486, and 0488) during the October-November 2003 super storms. The
  CMEs were accompanied by X-class flares, solar energetic particles,
  and interplanetary shocks. We compare the statistical properties of
  these super-storm CMEs with those of the general population of CMEs
  observed during cycle 23. We find that (i) the super-storm CMEs are
  faster and wider than average, and hence possess enormous energy,
  (ii) nearly 20 percent of the ultra-fast CMEs (speed &gt; 2000 km/s)
  occurred during the October-November interval, including the fastest
  CME of cycle 23 (2700 km/s), and (iii) the rate of full-halo CMEs was
  nearly four times the average rate during cycle 23. As expected, many
  of these CMEs were driving shocks near the Sun as inferred from the
  Wind/WAVES radio data and at least eight of them impacted Earth. These
  strong shocks accelerated solar energetic particles, which remained at
  hazardous levels for many days. We discuss the implications of these
  extreme properties of CMEs for the solar energy source.

---------------------------------------------------------
Title: Shock Evolution During 29 - 06 November 2003 period of
    Solar-Flare-CME-Shock-Geomagnetic Storms
Authors: Wu, C.; Wu, S.; Dryer, M.; Fry, C.; Berdichevsky, D.; Smith,
   Z.; Gopalswamy, N.; Zurbuchen, T.; Smith, C.; Detman, T.
2004AGUSMSH51A..14W    Altcode:
  During the period 29 October - 6 November four shocks were observed
  at Earth by ACE/SWEPAM/MAG and ACE/SWICS on 29 October, 30 October,
  4 November, and 6 November. Two distinct and very intense geomagnetic
  storms, associated with the X17.2 and X10/2B flares, rank as the
  largest storms of Solar Cycle 23. For example, the X17.2 flare (28
  October, S16E08 in AR0486), via its associated halo CME and shock wave,
  was responsible for the Dst = -347 nT index on 30 October 2003. We
  will present the use of an adaptive grid 2D MHD model to study these
  four shocks in detail. Accordingly, four separate pressure pulses,
  at the appropriate times and with different strengths and duration are
  introduced at the Sun to mimic the four flares. The results show that
  the simulated solar wind velocity time series successfully match the
  observations at L1.

---------------------------------------------------------
Title: Sun-Earth Propagation Time of the October - November 2003
    Shocks
Authors: Lara, A.; Gopalswamy, N.; Yashiro, S.
2004AGUSMSH51A..06L    Altcode:
  We computed the radial and expansion speed profiles of the CMEs that
  resulted in shocks detected at 1 AU, in order to evaluate the empirical
  shock arrival (ESA) model. The CMEs were observed by the Large Angle
  and Spectrometric Coronagraph (LASCO) on board SOHO during October -
  November 2003 period. The shocks were detected by CELIAS/MTOF Proton
  Monitor on board SOHO and ACE spacecraft. The basic input to the ESA
  model is the CME speed. For limb events, we assume axial symmetry
  in order to obtain the most probable CME speed in the Sun-Earth
  direction. We apply the ESA model to obtain the travel times of shocks
  driven by Earth-directed and limb CMEs which had in situ observations at
  1AU. For most cases the difference between the predicted and observed
  shock arrival times is negligible. We discuss these differences and
  their possible causes. Work supported by NASA/LWS and NSF/SHINE programs

---------------------------------------------------------
Title: Characteristic Periodicities in the Coronal Mass Ejection
    Production
Authors: Lara, A.; Gopalswamy, N.; Yashiro, S.
2004AAS...204.3806L    Altcode: 2004BAAS...36..713L
  The solar activity is cyclic by nature, some periods of activity are
  obvious and well known and some are hidden, but all of them should
  be related to fundamental processes in the solar interior like
  the dynamo. The search for hidden periodicities, which can give us
  information about the solar activity causes, has been done for many
  years with different degrees of success. Almost all measurable solar
  parameters have been subject to a power spectral analysis and now
  there are some well known periodicities related to such parameters. On
  the other hand there are some events like Coronal Mass Ejections
  (CMEs) which, until recently, were difficult to observe routinely
  and then, we did not have a reliable database to perform a power
  spectrum analysis. Using the LASCO/SOHO CME list, which contains the
  information of the CME characteristics observed from 1996 to 2003, we
  have now a reliable time series of the CME production during 8 years
  covering the minimum, maximum and part of the declining phases of solar
  activity cycle 23, in this work we present preliminary results of the
  power spectral analysis of the CME activity. <P />This work work was
  supported by NASA/LWS and NSF/SHINE (ATM 0204588) programs

---------------------------------------------------------
Title: Plasma and magnetic field of the solar wind
Authors: Gopalswamy, N.
2004cosp...35.2396G    Altcode: 2004cosp.meet.2396G
  Earth is always embedded in one of the three types of flows related to
  coronal mass ejections (CMEs), slow solar wind or fast solar wind. The
  topology of the magnetic field is different in the CME-related
  flows compared to the other two. I discuss the solar sources of the
  three types of flows. In particular, the relationship between CMEs
  in the solar wind and their solar counterparts will be explored to
  understand the possible reasons for the different number and speed
  distributions. Earth-directed CMEs constitute a special population
  of CMEs because they directly impact Earth. Earth-directed halo
  CMEs also seem to have properties different from the ordinary CMEs:
  their average speed is twice that of the general population. Finally,
  the solar cycle variation of the number of instances of CME-related
  flows at Earth will be compared with the occurrence rates of CMEs,
  solar energetic particle events, and interplanetary type II radio
  bursts produced by CME-driven shocks.

---------------------------------------------------------
Title: Variability of solar eruptions during cycle 23
Authors: Gopalswamy, N.; Nunes, S.; Yashiro, S.; Howard, R. A.
2004AdSpR..34..391G    Altcode:
  We report on the solar cycle variation of the rate of coronal mass
  ejections (CMEs), their mean and median speeds, and the rate of type II
  radio bursts. We found that both CME rate and speed (mean and median)
  increased from solar minimum to maximum by factors of 10 and 2,
  respectively. The CME rate during solar maximum is nearly twice the
  rates quoted previously. Large spikes in the speed variation were
  due to active regions that were highly active. The poor correlation
  between metric and DH type II bursts is confirmed, and the difference
  is attributed to the different Alfven speeds in the respective source
  regions.

---------------------------------------------------------
Title: Prominence eruptions and coronal mass ejection: a statistical
    study using microwave observations
Authors: Gopalswamy, N.; Lu, W.; Yashiro, S.; Shimojo, M.; Shibasaki,
   K.
2004naoj.book...18G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: On coronal streamer changes
Authors: Gopalswamy, N.; Shimojo, M.; Lu, W.; Yashiro, S.; Shibasaki,
   K.; Howard, R. A.
2004AdSpR..33..676G    Altcode:
  Coronal streamer represents one of the pre-eruption configurations
  of coronal mass ejections (CMEs), because they overlie prominences
  and often possess all the substructures of CMEs. In this paper,
  we report on a study of streamer changes associated with prominence
  eruptions. The prominence eruptions and streamer changes were observed
  by the Nobeyama radioheliograph and Solar and Heliospheric Observatory
  (SOHO), respectively. Multiwavelength data showed that at least one of
  the streamer events involved heating and small-scale material ejection
  that subsequently stalled. After presenting illustrative examples,
  we compare the properties of the streamer-related events with those of
  general population of prominence events. We find that the properties
  of streamer-related prominence events are closer to those of prominence
  eruptions with transverse trajectories.

---------------------------------------------------------
Title: Composition and magnetic structure of interplanetary coronal
    mass ejections at 1 AU
Authors: Aguilar-Rodriguez, E.; Blanco-Cano, X.; Gopalswamy, N.
2004cosp...35.2411A    Altcode: 2004cosp.meet.2411A
  We present a combined study of magnetic structure and charge state
  ratio of interplanetary coronal mass ejections (ICMEs) observed in
  interplanetary space by ACE and Wind spacecrafts. Measurements
  of abundances and charge state ratio of heavy ions
  (e.g. O<SUP>+7</SUP>/O<SUP>+6</SUP>, C<SUP>+5</SUP>/C<SUP>+6</SUP>,
  and Mg/O) in the solar wind as well as magnetic field structure are
  important tracers for physical conditions and processes in the source
  regions of the solar wind. We used ion composition (ACE), plasma (Wind)
  and magnetic field (Wind and ACE) data over a period of time from 1998
  to 2002. Using the low proton temperature criterion, a common plasma
  signature of ICMEs, we identified 154 events which were classified as
  magnetic cloud, non-cloud and complex ICMEs. The later one is refered
  to the overtaking of succesive ICMEs which can include both magnetic
  clouds and non-cloud ejecta. We discuss the differences and similarities
  of our results with those of previous studies. Supported by NSF/SHINE,
  NASA/LWS, and CONACyT.

---------------------------------------------------------
Title: Coronal Mass Ejections and Galactic Cosmic Ray Modulation
Authors: Lara, A.; Gopalswamy, N.; Caballero, R.; Yashiro, S.
2004cosp...35.2926L    Altcode: 2004cosp.meet.2926L
  We present a study of the long term evolution of Coronal Mass Ejections
  (CME) observed by LASCO/SOHO during the ascending, maximum and part
  of the descending phase of cycle 23 and its relation with the galactic
  cosmic ray (GCR) intensity modulation observed at one astronomical unit
  by Climax Neutron Monitor and IMP-8 spacecraft. We compare the long
  term GCR modulation with the CME production at low and high latitudes
  and CME parameters (width and speed). We found a very high (∼ 0.94)
  correlation between the number of high latitude CMEs and GCR during
  the ascending phase of solar cycle 23.

---------------------------------------------------------
Title: Coronal Mass Ejections and Solar Particle Events in Solar
    Cycle 23
Authors: Gopalswamy, N.
2004cosp...35.2358G    Altcode: 2004cosp.meet.2358G
  I provide an overview of the coronal mass ejection (CME) phenomenon
  as recorded primarily by the Solar and Heliospheric Observatory
  (SOHO) mission during the current solar activity cycle (23). After
  summarizing the statistical properties of CMEs and their solar-cycle
  variation, a discussion on the CME-associated activities will be
  presented. Particular emphasis will be placed on solar energetic
  particles (SEPs), which are related to CMEs that are faster and wider on
  average. Even though it is generally accepted that large SEP events are
  due to CME-driven shocks, the correlation between the two phenomena is
  less than perfect. Reasons for this poor correlation will be explored,
  including the influence of preceding CMEs. Fast and wide CMEs also
  produce long-wavelength radio bursts, so the connection between SEP
  events and radio bursts will be explored. Finally, I will discuss the
  implications of CMEs to the evolution of the global solar magnetic
  field and to the 22-year cosmic ray modulation cycle.

---------------------------------------------------------
Title: Estimation of solar wind speed within 20Rs of the Sun by
    using limb CMEs
Authors: Nakagawa, T.; Gopalswamy, N.; Yashiro, S.; Matsuoka, A.;
   Nozomi/Mgf Team
2004cosp...35.1632N    Altcode: 2004cosp.meet.1632N
  The speeds of propagation of CMEs in interplanetary space are less
  distributed than their initial speeds measured on their departure
  from the limb of the Sun. Gopalswamy et al.(2000, 2001) presented a
  linear relationship between initial speeds of limb CMEs and their
  average acceleration during their travel time in interplanetary
  space. The linear relationship suggests that some dragging force
  is acting on CMEs, depending on difference in speed between the
  CME and their ambient plasmas. The ambient speed obtained from the
  coeficcients of the linear relationship was 406 km/s, which is nearly
  the same as the real solar wind speed. If similar relationship holds
  within 20 solar radii from the Sun, it would give information on
  the initial speed of 'ambient' solar wind in the vicinity of the
  Sun. The relationship between the initial acceleration and the
  initial speeds of limb CMEs was examined by using SOHO/LASCO CME
  Catalogue (http://cdaw.gsfc.nasa.gov/CME_list/). Coefficients of
  correlation between the initial acceleration and the initial speeds
  of low-latitude CMEs were calculated by sliding 27-day windows in
  1999. Although there were many cases where linear relationship was not
  clear, we found significant number of periods for which correlation
  coefficient was fairly good (from -0.6 to -1). For such cases, the
  'ambient' solar wind speed within 20 solar radii was estimated to be
  150 - 570 km/s. It is somewhat slower than but close to the speeds
  of real solar wind measured in interplanetary space. It suggests
  that low-latitude solar wind plasma was accelerated within a short
  distance. It may also indicate that coronal holes are not the only
  source of the solar wind. The 'ambient' speeds thus obtained did not
  always agreed with simultaneous, in-situ measurements by NOZOMI and
  ACE. Estimation of 'ambient' speed was also carried out by using CMEs
  that appeared in higher latitude, but no latitudinal dependence was
  found. Acknowledgments:This CME catalog is generated and maintained
  by NASA and The Catholic University of America in cooperation with
  the Naval Research Laboratory. SOHO is a project of international
  cooperation between ESA and NASA. Reference: Gopalswamy et al., GRL,
  27, p145, 2000. Gopalswamy et al., JGR, 106, p29207, 2001.

---------------------------------------------------------
Title: Type II Radio Bursts and Energetic Solar Eruptions
Authors: Gopalswamy, N.; Nunes, S.; Yashiro, S.; Howard, R. A.;
   Kaiser, M. L.
2003AGUFMSH42C0556G    Altcode:
  Type II radio bursts at decameter-hectometric (DH) and kilometric
  wavelengths are indicative of CME-driven shocks in the interplanetary
  medium. Only a subset of these type II bursts continue from the DH
  to the km regimes. We report on a study of these long-lasting type II
  bursts using data from the Wind/WAVES experiment in conjunction with
  white-light coronal mass ejection (CME) data from SOHO. We find the
  majority of these events (80 percent) are also associated with metric
  Type II bursts. We also studied the properties of the associated CMEs
  and found them to be the most energetic when compared to CMEs associated
  with bursts in any single wavelength regime.

---------------------------------------------------------
Title: Merged interaction regions at 1 AU
Authors: Burlaga, L.; Berdichevsky, D.; Gopalswamy, N.; Lepping, R.;
   Zurbuchen, T.
2003JGRA..108.1425B    Altcode:
  We discuss the existence of large, complex merged interaction regions
  (MIRs) in the solar wind near Earth. MIRs can have configurations that
  cause more prolonged geomagnetic effects than a single flow structure. A
  MIR or successive MIRs can produce relatively long lasting Forbush
  decreases at 1 AU. We illustrate MIRs at 1 AU with two examples (MIR-1
  and MIR-2) seen by WIND and ACE in the interval from 18 March through
  29 March 2002. We determined the probable structure and origin of
  each in terms of interacting flows and shocks using in situ and solar
  observations, but we emphasize that there are uncertainties that cannot
  be resolved with these data alone. The MIRs were relatively large
  structures with radial extent ~2/3 and 3/4 AU, respectively. MIR-1
  was formed by interactions related to at least two complex ejecta,
  a magnetic cloud, and two shocks. MIR-2 was related to a corotating
  stream, the heliospheric plasma sheet (HPS), two complex ejecta, a
  magnetic cloud and at least two shocks. A MIR can evolve significantly
  while it moves to 1 AU, and memory of the conditions near the Sun
  is lost in the process. Thus one cannot unambiguously determine the
  structure of a MIR and the manner in which it formed using observations
  from a single spacecraft at 1 AU. The magnetic field strength profiles
  in MIRs are not correlated with the speed and density profiles so
  that one cannot infer the magnetic field strength in MIRs from remote
  sensing observation that give density and speed information. It will be
  possible to better understand the dynamical processes leading to the
  formation of MIRs with remote sensing observations, but they cannot
  measure the magnetic fields in MIRs.

---------------------------------------------------------
Title: Radio Coverage from Chromosphere to Earth: FASR-LOFAR-SIRA
    Synergy
Authors: Gary, D. E.; Kassim, N.; Gopalswamy, N.; Aschwanden, M. J.
2003AGUFMSH42E..02G    Altcode:
  Radio emission is uniquely sensitive to a number of key plasma
  parameters (magnetic field, temperature, density, high-energy
  electrons, and various plasma waves) over heights ranging without
  gaps from the chromosphere, throughout the corona and heliosphere, to
  the Earth. Two ground-based radio arrays, the Frequency Agile Solar
  Radiotelescope (FASR) and the Low Frequency Array (LOFAR), together
  with the space-based Solar Imaging Radio Array (SIRA) are planned
  that will for the first time provide direct imaging of disturbances
  over this vast height range through interferometric imaging over their
  equally impressive frequency range of 24 GHz to 30 kHz. We describe the
  science goals of these instruments, focusing especially on the science
  addressed jointly by all three instruments. Among the examples are
  (1) simultaneous imaging of CMEs, flaring loops, and shock-associated
  (type II) emission and (2) imaging the propagation of electrons on
  open field lines (type III), from their acceleration point through
  the corona and heliosphere to the point where they are measured in
  situ by near-Earth spacecraft. In addition to spatially relating the
  different phenomena, the spectral information is rich in quantitative
  diagnostics. We give some examples of the revolutionary results we
  can expect from the combined instruments.

---------------------------------------------------------
Title: Comment on “Coronal mass ejections, interplanetary ejecta
    and geomagnetic storms” by H. V. Cane, I. G. Richardson, and
    O. C. St. Cyr
Authors: Gopalswamy, N.; Manoharan, P. K.; Yashiro, S.
2003GeoRL..30.2232G    Altcode: 2003GeoRL..30xSSC1G
  <A href="/journals/gl/gl0324/2003GL017562/index.html">Abstract
  Available</A> from <A href="http://www.agu.org">AGU</A>

---------------------------------------------------------
Title: Key Issues Related to Solar Sources and Interplanetary
    Propagation of the April 2002 Events
Authors: Gopalswamy, N.
2003AGUFMSM41A..02G    Altcode:
  A summary of the solar events such as coronal mass ejections (CMEs)
  and flares associated with the April 2002 storms will be provided. In
  particular events from the primary active region, AR9906 and the
  underlying magnetic configuration will be discussed. The connection
  of these CMEs to the interplanetary shocks and the solar energetic
  particles events will be explored. Based on the arrival times of the
  interplanetary CMEs and shocks, the evolution of these disturbances as
  they propagated between the Sun and Earth will be described. Finally,
  a comparison of the April 2002 events with other geoeffective events
  will be made.

---------------------------------------------------------
Title: Probing Solar Energetic Particles with SIRA
Authors: Aschwanden, M. J.; Nitta, N.; Lemaster, E.; Byler, E.; Gary,
   D.; Kassim, N.; Gopalswamy, N.
2003AGUFMSH42C0555A    Altcode:
  The space-based SIRA (Solar Imaging Radio Array) will provide a powerful
  capability to track high energy particles from solar flare and CME sites
  through interplanetary/heliospheric space all the way to Earth. Together
  with two other overlapping planned radio interferometers, i.e., FASR
  (Frequency-Agile Solar Radiotelescope) and LOFAR (Low-Frequency Array)
  the entire plasma frequency range from 30 GHz all the way down to
  the plasma frequency cutoff of 30 kHz at 1 AU will be covered. These
  instruments will track the magnetic trajectory of high energy particles,
  beam-driven radio emission, and localize the acceleration sites in
  the corona or interplanetary shocks. We simulate some CME and type III
  events, as they will be mapped with these instruments, using realistic
  scattering functions of radio waves on coronal and heliospheric density
  inhomogeneities.

---------------------------------------------------------
Title: Coronal Mass Ejections, Flares and Type II Radio Bursts
Authors: Rosas, A. M.; Gopalswamy, N.; Kaiser, M. L.; Yahsiro, S.;
   Nunes, S.
2003AGUFMSH42C0559R    Altcode:
  An investigation of 210 interplanetary type II radio bursts and the
  associated white-light coronal mass ejections (CMEs) is presented. The
  radio bursts were detected by the Wind/WAVES experiment in the 1-14
  MHz (decameter-hectometric, DH) range, while the CMEs were observed
  by the Solar and Heliospheric Observatory (SOHO). The study period,
  1997-2002, encompasses the current solar cycle (23) between minimum and
  beyond maximum. We could only find 108 solar flares associated with
  DH type IIs. We obtained the difference onset times (solar flare -
  DH type II) and found that DH type IIs start at the same time as the
  flares. On the other hand the difference between CME and DH type II
  onset times is indicates that the type II bursts occur well after the
  CME onset. The present study suggests that the CMEs are more likely
  to be the source of the shocks responsible for the type II bursts. We
  extend the study to metric type II bursts and obtained similar results.

---------------------------------------------------------
Title: Coronal Mass Ejections and Solar Polarity Reversal
Authors: Gopalswamy, N.; Lara, A.; Yashiro, S.; Howard, R. A.
2003ApJ...598L..63G    Altcode:
  We report on a close relationship between the solar polarity reversal
  and the cessation of high-latitude coronal mass ejections (CMEs). This
  result holds good for individual poles of the Sun for cycles 21 and
  23, for which CME data are available. The high-latitude CMEs provide a
  natural explanation for the disappearance of the polar crown filaments
  (PCFs) that rush the poles. The PCFs, which are closed field structures,
  need to be removed before the poles could acquire open field structure
  of the opposite polarity. Inclusion of CMEs along with the photospheric
  and subphotospheric processes completes the full set of phenomena to
  be explained by any solar dynamo theory.

---------------------------------------------------------
Title: Dynamics of coronal mass ejections in the near-Sun
    interplanetary space
Authors: Vrsnak, B.; Ruzdajak, D.; Sudar, D.; Gopalswamy, N.
2003ESASP.535..517V    Altcode: 2003iscs.symp..517V
  Kinematics of more than 5000 coronal mass ejections (CMEs) measured
  between 2 and 30 solar radii is investigated. A distinct relationship
  between the late-phase acceleration of CMEs and their velocities is
  found. It can be represented in the form a<SUB>[m s<SUP>-2</SUP>]</SUB>
  = -0.02(v-400)<SUB>[km s<SUP>-1</SUP>]</SUB>. The relationship is
  interpreted in terms of coupling of the CME motion and the solar wind,
  i.e., by the action of the aerodynamic drag. The results indicate that
  in the considered radial distance range the Lorentz force acceleration
  becomes weak, in the majority of the events spanning between 0 and 10
  m s<SUP>-2</SUP>. Implications for the interplanetary motion of CMEs
  are discussed, emphasising the prediction of the 1 a.u. arrival time.

---------------------------------------------------------
Title: Variations of magnetic clouds and CMEs with solar activity
    cycle
Authors: Wu, Chin-Chun; Lepping, R. P.; Gopalswamy, N.
2003ESASP.535..429W    Altcode: 2003iscs.symp..429W
  Sixty-eight magnetic clouds were observed by Wind during November 1994 -
  May 2002. The average occurrence rate is ~9 magnetic clouds per year for
  the overall period (68 events/7.6 years). It is found that some of the
  frequency of occurrence anomalies were during the early part of solar
  cycle 23: (I) only 4 clouds were observed in 1999, (II) an unusually
  large number of clouds (16 events) were observed in 1997 in which the
  Sun was starting to leave solar minimum. During the period of 1996-2001,
  the results also show: (1) the occurrence frequency of magnetic cloud
  appears to be related neither to the occurrence of solar coronal mass
  ejections (CMEs) as observed by SOHO nor to solar activity cycle,
  (2) the intensity of geomagnetic storms related to magnetic clouds is
  affected by both solar activity and the occurrence frequency of CMEs,
  and (3) ~91% of magnetic clouds induced geomagnetic storms.

---------------------------------------------------------
Title: Effect of CME Interactions on the Production of Solar
    Energetic Particles
Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Kaiser, M. L.;
   Howard, R. A.; Leske, R.; von Rosenvinge, T.; Reames, D. V.
2003AIPC..679..608G    Altcode:
  We analyzed a set of 52 fast and wide, frontside western hemispheric
  (FWFW) CMEs in conjunction with solar energetic particle (SEP) and
  radio burst data and found that 42 of these CMEs were associated
  with SEPs. All but two of the 42 SEP-associated FWFW CMEs (95%)
  were interacting with preceding CMEs or dense streamers. Most of
  the remaining 10 SEP-poor FWFW CMEs had either insignificant or no
  interaction with preceding CMEs or streamers, and were ejected into
  a tenuous corona. There is also a close association between type II
  radio bursts in the near-Sun interplanetary medium and SEP-associated
  FWFW CMEs suggesting that electron accelerators are also good proton
  accelerators.

---------------------------------------------------------
Title: A Numerical Study on the Evolution of CMEs and Shocks in the
    Interplanetary Medium
Authors: González-Esparza, J. A.; Lara, A.; Santillán, A.;
   Gopalswamy, N.
2003AIPC..679..206G    Altcode:
  We studied the evolution in the solar wind of four CMEs detected by
  SOHO-LASCO which were associated with ICMEs and interplanetary (IP)
  shocks detected afterward by Wind at 1 AU. The study is based on a
  1-D hydrodynamic single fluid model using the ZEUS code. These simple
  numerical simulations of CME like pulses illuminate several aspects of
  the heliocentric evolution of the ICME front and its associated IP shock
  and we were able to reproduce some characteristics of the IP shocks
  and ICMEs inferred from the two-point measurements from spacecraft. The
  simulation shows that ICMEs and IP shocks follow different evolutions
  in the interplanetary medium both having phases of about constant speed
  propagation followed by an exponential deceleration with heliocentric
  distance. IP shocks always propagate faster than their associated
  ICME drivers and the former began to decelerate well before the IP
  shock. The results indicate that, in general, although an IP shock is
  driven by its ICME in the inner heliosphere in most of the cases this
  is not true any more when they approach to 1 AU.

---------------------------------------------------------
Title: Coronal mass ejection activity during solar cycle 23
Authors: Gopalswamy, Nat; Lara, Alejandro; Yashiro, Seiji; Nunes,
   Steven; Howard, Russell A.
2003ESASP.535..403G    Altcode: 2003iscs.symp..403G
  We studied the solar cycle varition of various properties of coronal
  mass ejections (CMEs), such as daily CME rate, mean and median speeds,
  and the latitude of solar sources for cycle 23 (1996-2002). We find
  that (1) there is an order of magnitude increase in CME rate from the
  solar minimum (0.5/day) to maximum (6/day), (2) the maximum rate is
  significantly higher than previous estimates, (3) the mean and median
  speeds of CMEs also increase from minimum to maximum by a factor of 2,
  (4) the number of metric type II bursts (summed over CR) tracks CME
  rate, but the CME speed seems to be only of secondary importance,
  (5) for type II bursts originating farther from the Sun the CME
  speed is important, (6) the latitude distribution of CMEs separate the
  prominence-associated (high-latitude) and active-region associated CMEs,
  and (7) the rate of high-latitude CMEs shows north-south asymmetry and
  the cessation eruptions in the north and south roughly mark the polarity
  reversals. We compared the rates of the fast-and-wide CMEs, major solar
  flares, interplanetary (IP) shocks, long-wavelength type II bursts and
  large SEP events. This comparison revealed that the number of major
  flares is generally too large compared to all the other numbers. In
  other words, fast-and-wide CMEs, long-wavelength type II bursts,
  large SEP events, and IP shocks have a close physical relationship.

---------------------------------------------------------
Title: Coronal and Interplanetary Environment of Large Solar Energetic
    Particle Events
Authors: Gopalswamy, Nat; Yashiro, S.; Stenborg, G.; Howard, R. A.
2003ICRC....6.3549G    Altcode: 2003ICRC...28.3549G
  We studied the properties of coronal mass ejections (CMEs) associated
  with large solar energetic particle (SEP) events during 1997-2002
  and compared them with those of preceding CMEs from the same source
  region. The primary findings of this study are (1) High-intensity
  (&gt; 50 protons cm-2 s-1 sr-1 ) events are more likely to be preceded
  by other wide CMEs. (2) The preceding CMEs are faster and wider
  than average CMEs. (3) The primary CMEs often propagate through the
  near-Sun interplanetary medium severely disturb ed and distorted by
  the preceding CMEs.

---------------------------------------------------------
Title: Large solar energetic particle events of cycle 23: A global
    view
Authors: Gopalswamy, N.; Yashiro, S.; Lara, A.; Kaiser, M. L.;
   Thompson, B. J.; Gallagher, P. T.; Howard, R. A.
2003GeoRL..30.8015G    Altcode: 2003GeoRL..30lSEP3G
  We report on a study of all the large solar energetic particle
  (SEP) events that occurred during the minimum to maximum interval
  of solar cycle 23. The main results are: 1. The occurrence rate of
  the SEP events, long-wavelength type II bursts and the fast and wide
  frontside western hemispheric CMEs is quite similar, consistent with the
  scenario that CME-driven shocks accelerate both protons and electrons;
  major flares have a much higher rate. 2. The SEP intensity is better
  correlated with the CME speed than with the X-ray flare class. 3. CMEs
  associated with high-intensity SEPs are about 4 times more likely to
  be preceded by wide CMEs from the same solar source region, suggesting
  the importance of the preconditioning of the eruption region. We use
  a specific event to demonstrate that preceding eruption from a nearby
  source can significantly affect the properties of SEPs and type II
  radio bursts.

---------------------------------------------------------
Title: Solar and geospace connections of energetic particle events
Authors: Gopalswamy, N.
2003GeoRL..30.8013G    Altcode: 2003GeoRL..30lSEP1G
  A Coordinated Data Analysis Workshop (CDAW) was conducted recently
  to study the solar and geospace connections of large solar energetic
  particle (SEP) events of solar cycle 23 (up to the end of 2001). This
  paper summarizes the properties these events, the scientific issues
  discussed, and some of the results obtained during the workshop.

---------------------------------------------------------
Title: A statistical study of CMEs associated with metric type
    II bursts
Authors: Lara, A.; Gopalswamy, N.; Nunes, S.; Muñoz, G.; Yashiro, S.
2003GeoRL..30.8016L    Altcode: 2003GeoRL..30lSEP4L
  We present a statistical study of the characteristics of CMEs which
  show temporal association with type II bursts in the metric domain but
  not in the decameter/hectometric (DH) domain. This study is based on
  a set of 80 metric (m) type II bursts associated with surface events
  in the solar western hemisphere. It was found that in general, the
  distribution of the widths and speeds of the CMEs associated with metric
  (but not DH) type II bursts are shifted towards higher values compared
  to those of all CMEs observed by LASCO in the 1996-2001 period. We
  also found that these distributions have lower values than the same
  distributions of the CMEs associated with DH type II bursts. In terms
  of energy, this means that the CMEs associated only with metric type
  II bursts are more energetic (wider and faster) than regular CMEs but
  less energetic than the CMEs associated with DH type II bursts.

---------------------------------------------------------
Title: Solar Imaging Radio Array (SIRA): Radio Aperture Synthesis
    from Space
Authors: MacDowall, R.; Kaiser, M.; Gopalswamy, N.
2003SPD....34.2022M    Altcode: 2003BAAS...35Q.848M
  SIRA, the Solar Imaging Radio Array, will be a constellation of about
  16 microsats designed to image radio sources in the solar corona and
  heliosphere using aperture synthesis techniques. These images will
  permit the mapping and tracking of CME-driven shocks (type II radio
  bursts) and solar flare electrons (type III radio bursts) as a function
  of time from near the sun to 1 AU. Two dimensional imaging of the
  CME-driven shock front is important for determination of space weather
  effects of CMEs, whereas imaging of the ubiquitous type III bursts will
  permit the derivation of density maps in the outer corona and solar
  wind. This will be the first mission to image the heliosphere (and the
  celestial sphere) with good angular resolution at frequencies below
  the ionospheric cutoff ( 10 MHz). The radio images are intrinsically
  complementary to white-light coronograph data, such as those of SDO,
  and can play a valuable role in the NASA Living with a Star program.

---------------------------------------------------------
Title: Analysis of Onset Times between CMEs and Associated DH Type
    II Bursts
Authors: Rosas, A. M.; Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.;
   Howard, R. L.
2003SPD....34.0506R    Altcode: 2003BAAS...35..815R
  An investigation of 210 interplanetary type II radio bursts and the
  associated white-light coronal mass ejections (CMEs) is presented.The
  radio bursts were detected by the Wind/WAVES experiment in the 1-14 MHz
  (decameter-hectometric,DH) range, while the CMEs were observed by the
  Solar and Heliospheric Observatory (SOHO).The study period, 1997-2002,
  encompasses the current solar cycle (23) between minimum and beyond
  maximum. We find that 91% of CMEs have speeds greater than 450 km/s
  and 94% have angular widths greater than 60 degrees obtained from
  SOHO/LASCO C2 and C3 CME measurements.We made a linear and quadratic
  fit using CME height time measurements to extrapolate CME onset times
  to 2 and 1 solar radius. We find that the quadratic onset times (QOTs)
  illustrates less scatter in the difference times (CME onset time - DH
  onset time) than the linear onset times (LOTs). Both the QOT and LOT
  for 1 solar radius shows that ∼ 80% DH type II bursts occurred within
  1 hour of CME onset time and for 2 solar radius extrapolation shows
  ∼ 87%. Correlation coefficients were found to be very weak between
  difference times and CME longitude, speed, angular width, and DH type
  II starting frequency. We are continuing to investigate the outlier (DH
  type II bursts occurring more than 2 hours after CMEs) events.(1) The
  onset times and starting frequency of DH type IIs with respect to CME
  onset times provides insight into the coronal density distribution.(2)
  The relationship between CME onset time and the occurrence of the DH
  type II will be discussed in terms of the radial distribution of the
  Alfven speed near the Sun. <P />This work is supported by NASA living
  with a Star and NSF/SHINE (ATM 0204588) and AFOSR Programs.

---------------------------------------------------------
Title: Towards Automatic Tracking of Coronal Mass Ejections
Authors: Stenborg, G. A.; Cobelli, P. J.; Gopalswamy, N.; Yashiro, S.
2003SPD....34.0306S    Altcode: 2003BAAS...35..809S
  Tracing identifiable features of dynamical phenomena such as coronal
  mass ejections (CMEs), as they propagate through the corona, is a real
  challenge. In particular, different features from a single event usually
  display different velocities. Moreover, the lack of sharpness of the
  structures involved on top of the subjective nature of the measuring
  process makes it difficult to track the event unambiguously. To overcome
  the lack of sharpness, we developed a multiresolution image processing
  technique applicable to any 2D data set to enhance both boundaries and
  internal details of originally faint and diffuse structures. The method
  implemented employs a multi-level decomposition scheme (splitting
  algorithm of a wavelet packet on non-orthogonal wavelets) via the
  `a trous' wavelet transform, local noise reduction and interactive
  weighted recomposition. This approach represents a major advance
  towards unambiguous image interpretation and provides a means for the
  quantification of stationary and dynamic coronal structures required
  for conducting morphological studies. Moreover, it proved to be a
  necessary step in the development of a non-subjective technique for
  automatic tracking of CMEs. Examples based on LASCO-C1, -C2, -C3, and
  EIT data sets are shown. Different reconstruction strategies are also
  discussed. <P />This work is supported by NASA living with a Star and
  NSF/SHINE (ATM 0204588) Programs.

---------------------------------------------------------
Title: Long Lasting Type II Radio Bursts
Authors: Nunes, S.; Gopalswamy, N.; Yashiro, S.; Howard, R.
2003SPD....34.0607N    Altcode: 2003BAAS...35..818N
  Plasma frequencies starting in the decameter-hectametric (DH) regime and
  continuing into the kilometric (km) regime correspond to approximately
  to the entire Sun-Earth distance. Accordingly, we consider Type II radio
  bursts observed by the WAVES experiment on the WIND spacecraft that
  are observed from the DH to the km regimes and their association with
  white-light coronal mass ejections (CMEs). We find that approximately
  80% of these events are associated with metric Type II bursts observed
  on Earth. We also consider correlations of DH/km Type II's with
  sunspot numbers and other cyclical measures of solar activity, and
  properties of CMEs associated with DH/km Type II bursts. <P />This
  work is supported by the Air Force Office of Scientific Research,
  the National Science Foundation's SHINE Program, and NASA.

---------------------------------------------------------
Title: Why was there no Solar Energetic Particle Event Associated
    with the Gamma-ray-line Flare of 2002 July 23?
Authors: Gopalswamy, N.; Dennis, B. R.; Kaiser, M. L.; Krucker, S.;
   Lin, R. P.; Vourlidas, A.
2003SPD....34.2202G    Altcode: 2003BAAS...35..850G
  We investigated the coronal and interplanetary (IP) events associated
  with two X-class flares on 2002 July 20 and 23. Both flares were
  associated with ultra-fast (&gt;2000 km s<SUP>-1</SUP>) coronal mass
  ejections (CMEs) and IP shocks. We use white-light, EUV, hard X-ray and
  radio observations to trace the origin of the CMEs to active region
  0039 located close to the east limb. The July 20 flare was partly
  occulted by the east limb, yet it resulted in a major solar energetic
  particle event with intensity ∼ 20 pfu in the &gt;10 MeV channel
  (1 pfu = 1 particle per (cm<SUP>2</SUP> s sr MeV)). The July 23 event
  was the first gamma-ray-line flare detected by RHESSI, but it did
  not show any enhancement in SEPs above the elevated background from
  the July 20 event. We identified two distinguishing factors between
  the July 2 and July 23 CMEs: (1) The July 20 CME had a higher kinetic
  energy, and (2) The July 20 CME was interacting with another fast CME
  (1350 km s<SUP>-1</SUP>) that preceded by less than an hour from the
  same region; there were also two other CMEs on July 19 from the same
  region. Thus the coronal and IP environment of the July 20 event was
  highly disturbed due to preceding CMEs (as compared to the July 23
  event). We suggest that the different coronal/IP environments may be
  responsible for the lack of SEP event associated with the July 23 event.

---------------------------------------------------------
Title: Influence of CME interaction on the Propagation of
    Interplanetary Shocks
Authors: Manoharan, P. K.; Gopalswamy, N.; Yashiro, S.; Howard, R. A.
2003SPD....34.0610M    Altcode: 2003BAAS...35Q.819M
  We studied a large number of coronal mass ejections (CMEs) and their
  associated interplanetary (IP) shocks for the period 1996-2002, using
  white-light images from the Large Angle and Spectrometric Coronagraph
  (LASCO) on the Solar Heliospheric Observatory (SOHO) spacecraft and
  solar wind measurements from the Mass Time-of-Flight spectrometer
  (MTOF on SOHO) and Solar Wind Experiment (SWE on the WIND satellite)
  instrument. The 1-AU arrival times of the CME and its shock are
  obtained from the initial CME speed. We studied the influence of
  preceding CMEs on the propagation of the IP shocks. We note that the
  propagation characteristics of some of the fast CMEs and their shocks
  are modified by the interaction with the preceding CMEs. We also
  find that the arrival times of IP shocks show deviation from that of
  non-interacting cases. We use an empirical model to explain the change
  in the travel time of shocks. We also discuss other consequences in the
  solar wind caused by the CME interactions. <P />This work is supported
  by NASA living with a Star, NSF/SHINE (ATM 0204588), and AFOSR Programs.

---------------------------------------------------------
Title: Recent advances in long-wavelength radio physics of the Sun
Authors: Gopalswamy, N.
2003EAEJA.....4473G    Altcode:
  Low frequency imaging of the solar radio bursts provides the best means
  of studying the solar disturbances such as coronal mass ejections and
  shocks at the moment of their departure from the Sun. The radio bursts
  also provide information on the physical properties of the medium
  such as the density, temperature and magnetic field. Direct imaging of
  the quiet Sun also provides information on the outer corona. I review
  some of the results obtained from recent long-wavelength observations
  and summarize the relevance of these results to LOFAR. In addition,
  I discuss the significance of LOFAR to future low frequency imaging
  observations from space such as the Solar Imaging Radio Array (SIRA).

---------------------------------------------------------
Title: The Solar Radio Imaging Array (SIRA) microsatellite mission
Authors: MacDowall, R.; Gopalswamy, N.; Kaiser, M.
2003EAEJA....12917M    Altcode:
  SIRA, the Solar Imaging Radio Array, will be a constellation of about
  16 microsats designed to image radio sources in the solar corona
  and heliosphere using aperture synthesis techniques. These images
  will permit the mapping and tracking of CME-driven shocks (type II
  radio bursts) and solar flare electrons (type III radio bursts) as a
  function of time from near the sun to 1 AU. Two dimensional imaging
  of the CME-driven shock front is important for determination of space
  weather effects of CMEs, whereas imaging of the ubiquitous type III
  bursts will permit the derivation of density maps in the outer corona
  and solar wind. This will be the first mission to image the heliosphere
  (and the celestial sphere) with good angular resolution at frequencies
  below the ionospheric cutoff (~10 MHz). In this presentation, we
  highlight the ways in which SIRA is complementary to LOFAR and FASR.

---------------------------------------------------------
Title: Coronal mass ejections as a source of space Weather
Authors: Gopalswamy, N.
2003EAEJA.....4456G    Altcode:
  White-light and radio observations of solar eruptions obtained by SOHO
  and Wind, respectively have helped us understand the space weather
  aspect of coronal mass ejections (CMEs). From space weather point of
  CMEs are important in two respects: (1) CMEs departing from close to
  the disk center are important for producing geomagnetic storms, so it
  is important to understand how they evolve and when they arrive at the
  earth, (2) Fast and wide CMEs drive shocks and hence accelerate solar
  energetic particles detected in situ or via the long wavelength type
  II radio bursts. The SEP-associated CMEs can depart from the Sun from
  any longitude, but western events are more geoeffective. Recent results
  show that only 1-2 percent of all CMEs are important for space weather
  purposes. In this paper, we review the recent results obtained on
  these two populations of CMEs in comparison with the general population.

---------------------------------------------------------
Title: Low frequency radio astronomy from space: the Solar Radio
    Imaging Array
Authors: MacDowall, R.; Gopalswamy, N.; Kaiser, M.
2003EAEJA....12863M    Altcode:
  SIRA, the Solar Imaging Radio Array, will be a constellation of
  about 16 microsats designed to image radio sources in the solar
  corona and heliosphere using aperture synthesis techniques. Using
  crossed dipoles and high dynamic range radio receivers, SIRA will
  observe solar radio emissions in the frequency range from ~15 MHz to
  ~30 kHz. These frequencies correspond to distances of 2 R_sun to 1
  AU. Frequency spacing and time resolution will be optimized for solar
  burst analysis. The quasi-spherical constellation (diameter 25-50
  km) will provide appropriate baselines for angular resolution of ~10
  arcsec at 15 MHz . Several orbit possibilities are currently under
  consideration. Rapid data processing for space weather prediction
  of CME arrival at 1 AU is a major goal. It is anticipated that this
  mission will be proposed for the next NASA MIDEX opportunity.

---------------------------------------------------------
Title: Prominence Eruptions and Coronal Mass Ejection: A Statistical
    Study Using Microwave Observations
Authors: Gopalswamy, N.; Shimojo, M.; Lu, W.; Yashiro, S.; Shibasaki,
   K.; Howard, R. A.
2003ApJ...586..562G    Altcode:
  We present the results of a statistical study of a large
  number of solar prominence events (PEs) observed by the Nobeyama
  Radioheliograph. We studied the association rate, relative timing,
  and spatial correspondence between PEs and coronal mass ejections
  (CMEs). We classified the PEs as radial and transverse, depending on
  whether the prominence moved predominantly in the radial or horizontal
  direction. The radial events were faster and attained a larger height
  above the solar surface than the transverse events. Out of the 186
  events studied, 152 (82%) were radial events, while only 34 (18%)
  were transverse events. Comparison with white-light CME data revealed
  that 134 (72%) PEs were clearly associated with CMEs. We compare our
  results with those of other studies involving PEs and white-light CMEs
  in order to address the controversy in the rate of association between
  CMEs and prominence eruptions. We also studied the temporal and spatial
  relationship between prominence and CME events. The CMEs and PEs seem
  to start roughly at the same time. There was no solar cycle dependence
  of the temporal relationship. The spatial relationship was, however,
  solar cycle dependent. During the solar minimum, the central position
  angle of the CMEs had a tendency to be offset closer to the equator
  as compared to that of the PE, while no such effect was seen during
  solar maximum.

---------------------------------------------------------
Title: A New Method for Estimating Widths, Velocities, and Source
    Location of Halo Coronal Mass Ejections
Authors: Michałek, G.; Gopalswamy, N.; Yashiro, S.
2003ApJ...584..472M    Altcode: 2007arXiv0710.4524M
  It is well known that coronagraphic observations of halo coronal mass
  ejections (CMEs) are subject to projection effects. Viewing in the plane
  of the sky does not allow us to determine the crucial parameters that
  define the geoeffectiveness of CMEs, such as the space speed, width,
  or source location. Assuming that halo CMEs have constant velocities,
  are symmetric, and propagate with constant angular widths, at least
  in their early phase, we have developed a technique that allows us to
  obtain the required parameters. This technique requires measurements
  of sky-plane speeds and the moments of the first appearance of the
  halo CMEs above opposite limbs. We apply this technique to obtain the
  parameters of all the halo CMEs observed by the Solar and Heliospheric
  Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph
  experiment until the end of 2000. We also present a statistical summary
  of these derived parameters of the halo CMEs.

---------------------------------------------------------
Title: Coronal mass ejection interaction and particle acceleration
    during the 2001 April 14 15 events
Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.
2003AdSpR..32.2613G    Altcode:
  Two successive solar energetic particle (SEP) events associated with
  fast and wide coronal mass ejections (CMEs) on 2001 April 14 and 15
  are compared. The weak SEP event of April 14 associated with an 830
  km/s CME and an M1.0 flare was the largest impulsive event of cycle
  23. The April 15 event, the largest ground level event of cycle 23, was
  three orders of magnitude more intense than the April 14 <SUP>th</SUP>
  event and was associated with a faster CME (1200 km/s) and an X14.4
  flare. We compiled and compared all the activities (flares, CMEs,
  interplanetary conditions and radio bursts) associated with the two SEP
  events to understand the intensity difference between them. Different
  coronal and interplanetary environments of the two events (presence
  of preceding CME and seed particles ahead of the April 15 event)
  may explain the intensity difference.

---------------------------------------------------------
Title: Properties of narrow coronal mass ejections observed with LASCO
Authors: Yashiro, S.; Gopalswamy, N.; Michalek, G.; Howard, R. A.
2003AdSpR..32.2631Y    Altcode:
  We report the statistical properties of narrow coronal mass ejections
  (CMEs, angular width &lt; 20°) withparticular emphasis on comparison
  with normal CMEs. We investigated 806 narrow CMEs from an online
  LASCO/CME catalog and found that (1) the fraction of narrow CMEs
  increases from 12% to 22% towards solar maximum, (2) during the solar
  maximum, the narrow CMEs are generally faster than normal ones, (3)
  the maximum speed of narrow CMEs (1141 km s <SUP>-1</SUP>) is much
  smaller than that of the normal CMEs (2604 km s <SUP>-1</SUP>). These
  results imply that narrow CMEs do not form a subset of normal CMEs
  and have a different acceleration mechanism from normal CMEs.

---------------------------------------------------------
Title: A numerical study on the acceleration and transit time of
    coronal mass ejections in the interplanetary medium
Authors: GonzáLez-Esparza, J. AméRico; Lara, Alejandro;
   PéRez-Tijerina, Eduardo; SantilláN, Alfredo; Gopalswamy, Nat
2003JGRA..108.1039G    Altcode:
  Recently, an empirical model of the acceleration/deceleration of
  coronal mass ejections (CMEs) as they propagate through the solar wind
  was developed using near-Sun (coronagraphic) and near-Earth (in situ)
  observations [, 2000, 2001a]. This model states and quantifies the
  fact that slow CMEs are accelerated and fast CMEs are decelerated
  toward the ambient solar wind speed (∼400 km/s). In this work we
  study the propagation of CMEs from near the Sun (0.083 AU) to 1 AU
  using numerical simulations and compare the results with those of the
  empirical model. This is a parametric study of CME-like disturbances
  in the solar wind using a one-dimensional, hydrodynamic single-fluid
  model. Simulated CMEs are propagated through a variable ambient
  solar wind and their 1 AU characteristics are derived to compare
  with observations and the empirical CME arrival model. We were able
  to reproduce the general characteristics of the prediction model
  and to obtain reasonable agreement with two-point measurements from
  spacecraft. Our results also show that the dynamical evolution of
  fast CMEs has three phases: (1) an abrupt and strong deceleration
  just after their injection against the ambient wind, which ceases
  before 0.1 AU, followed by (2) a constant speed propagation until
  about 0.45 AU, and, finally, (3) a gradual and small deceleration
  that continues beyond 1 AU. The results show that it is somewhat
  difficult to predict the arrival time of slow CMEs (V<SUB>cme</SUB>
  &lt; 400 km/s) probably because the travel time depends not only on
  the CME initial speed but also on the characteristics of the ambient
  solar wind and CMEs. However, the simulations show that the arrival
  time of very fast CMEs (V<SUB>cme</SUB> &gt; 1000 km/s) has a smaller
  dispersion so the prediction can be more accurate.

---------------------------------------------------------
Title: Coronal mass ejections: Initiation and detection
Authors: Gopalswamy, N.
2003AdSpR..31..869G    Altcode:
  Coronal mass ejections (CMEs) are large-scale magnetic structures
  expelled from the Sun due to MHD processes involving interaction
  between plasma and magnetic field in closed field regions. I provide
  a summary of the observational signatures and current models on CME
  initiation. I also discuss the multiwavelength signatures of CMEs,
  which have helped us obtain a global picture of the CME phenomenon in
  the inner heliosphere.

---------------------------------------------------------
Title: Arrival time of coronal mass ejections
Authors: Michalek, G.; Gopalswamy, N.; Chane, E.
2002ESASP.506..177M    Altcode: 2002svco.conf..177M; 2002ESPM...10..177M
  Halo coronal mass ejections (CMEs), originating near the disk
  center, cause the severest geomagnetic storms. Thus, estimation
  of the arrival of magnetic clouds in the Earth vicinity is very
  important in space weather investigation. We describe an empirical
  model to predict the 1 AU arrival time of CMEs. This model is
  based on the effective acceleration described by Gopalswamy et. al
  (2000). It was improved by considering halo CMEs for which the space
  velocities are determined. This allowed us to receive the more accurate
  estimations. The new model reduces the average prediction error from
  ≍10 to ≍5 hours.

---------------------------------------------------------
Title: Solar, Interplanetary, and Geospace Disturbances Associated
    with the April 2002 Coronal Mass Ejections
Authors: Gopalswamy, N.; Yashiro, S.; St. Cyr, O.; Lawrence, G.;
   Kaiser, M. L.; Gurman, J. B.; Howard, R. A.
2002AGUFMSA12A..02G    Altcode:
  The Solar and Heliospheric Observatory (SOHO) detected a large number of
  coronal mass ejections (CMEs) during the April 14-24, 2002 period. We
  describe the properties of these CMEs and contrast them with those of
  the general population of CMEs. We explore the connection of these
  CMEs to the interplanetary shocks and the solar energetic particles
  events using Wind and GOES data, respectively. We assess the extent of
  preconditioning of the corona by repeated flaring and mass ejections
  from the active regions involved. Based on the arrival times of the
  interplanetary CMEs and shocks, we discuss the evolution of these
  disturbances as they propagated between the Sun and Earth. We compare
  the extended nature of the main phase of the complex geomagnetic storm
  to other other similar extended storm periods

---------------------------------------------------------
Title: A Statistical Study of Two Classes of Coronal Mass Ejections
Authors: Moon, Y. -J.; Choe, G. S.; Wang, Haimin; Park, Y. D.;
   Gopalswamy, N.; Yang, Guo; Yashiro, S.
2002ApJ...581..694M    Altcode:
  A comprehensive statistical study is performed to address the question
  of whether two classes of coronal mass ejections (CMEs) exist. A
  total of 3217 CME events observed by SOHO/LASCO in 1996-2000 have
  been analyzed. We have examined the distributions of CMEs according to
  speed and acceleration, respectively, and investigated the correlation
  between speed and acceleration of CMEs. This statistical analysis is
  conducted for two subsets containing those CMEs that show a temporal and
  spatial association either with GOES X-ray solar flares or with eruptive
  filaments. We have found that CMEs associated with flares have a higher
  median speed than those associated with eruptive filaments and that the
  median speed of CMEs associated with strong flares is higher than that
  of weak-flare-associated CMEs. The distribution of CME acceleration
  shows a conspicuous peak near zero, not only for the whole data set,
  but also for the two subsets associated either with solar flares or
  with eruptive filaments. However, we have confirmed that the CMEs
  associated with major flares tend to be more decelerated than the CMEs
  related to eruptive filaments. The fraction of flare-associated CMEs
  has a tendency to increase with the CME speed, whereas the fraction
  of eruptive-filament-associated CMEs tends to decrease with the CME
  speed. This result supports the concept of two CME classes. We have
  found a possibility of two components in the CME speed distribution
  for both the CME data associated with flares larger than M1 class and
  the CME data related with limb flares. Our results suggest that the
  apparent single-peak distribution of CME speed can be attributed to
  the projection effect and possibly to abundance of small flares too. We
  also note that there is a possible correlation between the speed of CMEs
  and the time-integrated X-ray flux of the CME-associated limb flares.

---------------------------------------------------------
Title: The International Heliophysical Year (IHY)
Authors: Davila, J. M.; Harrison, R.; Poland, A.; Thompson, B.;
   Gopalswamy, N.
2002AGUFMSH21A0518D    Altcode:
  In 1957 a program of international research, inspired by the
  International Polar Years of 1882-83 and 1932-33, was organized as
  the International Geophysical Year (IGY) to study global phenomena of
  the Earth and geospace. The IGY involved about 60,000 scientists from
  66 nations, working at thousands of stations, from pole to pole to
  obtain simultaneous, global observations on Earth and in space. There
  had never been anything like it before. The fiftieth anniversary of
  the International Geophysical Year will occur in 2007. We propose to
  organize an international program of scientific collaboration for this
  time period called the International Heliophysical Year (IHY). Like
  it predecessors, the IHY will focus on fundamental global questions
  of Earth science.

---------------------------------------------------------
Title: MHD modelling of CME and CME interactions in a bi-modal
solar wind: a preliminary analysis of the 20 January 2001 two CMEs
    interaction event
Authors: Wu, S. T.; Wang, A. H.; Gopalswamy, N.
2002ESASP.505..227W    Altcode: 2002solm.conf..227W; 2002IAUCo.188..227W
  Observations from SOHO and WIND reveal that coronal mass ejections
  (CMEs) cannibalize and deflect one another. CMEs also are accelerated
  and decelerated due to their interactions with the solar wind. These
  CME interactions with CME and with the solar wind result in producing
  significant differences in solar wind signatures as compared to
  isolated CME events. To understand these dynamical evolutionary
  processes, we have constructed a magnetohydrodynamic (MHD)
  simulation model based on a flux-rope and streamer model including
  bi-modal solar wind to investigate the physical processes of CME
  interactions. Specifically, the January 20, 2001 CME-CME interaction
  event recorded by SOHO/LASCO/C2/C3 are used to guide this simulation
  study. The results showed that CME cannibalism is caused by magnetic
  reconnection. The CME's acceleration and deceleration are caused by
  solar wind and the CME's deflection of one another.

---------------------------------------------------------
Title: Measurements of Three-dimensional Coronal Magnetic Fields
    from Coordinated Extreme-Ultraviolet and Radio Observations of a
    Solar Active Region Sunspot
Authors: Brosius, Jeffrey W.; Landi, Enrico; Cook, John W.; Newmark,
   Jeffrey S.; Gopalswamy, N.; Lara, Alejandro
2002ApJ...574..453B    Altcode:
  We observed NOAA Active Region 8108 around 1940 UT on 1997 November 18
  with the Very Large Array and with three instruments aboard the NASA/ESA
  Solar and Heliospheric Observatory satellite, including the Coronal
  Diagnostic Spectrometer, the EUV Imaging Telescope, and the Michelson
  Doppler Imager. We used the right-hand and left-hand circularly
  polarized components of the radio observing frequencies, along with
  the coordinated EUV observations, to derive the three-dimensional
  coronal magnetic field above the region's sunspot and its immediate
  surroundings. This was done by placing the largest possible harmonic
  (which corresponds to the smallest possible magnetic field strength)
  for each component of each radio frequency into appropriate atmospheric
  temperature intervals such that the calculated radio brightness
  temperatures at each spatial location match the corresponding
  observed values. The temperature dependence of the derived coronal
  magnetic field, B(x,y,T), is insensitive to uncertainties on the
  observed parameters and yields field strengths in excess of 580 G
  at 2×10<SUP>6</SUP> K and in excess of 1500 G at 1×10<SUP>6</SUP>
  K. The height dependence of the derived coronal magnetic field,
  B(x,y,h), varies significantly with our choice of magnetic scale height
  L<SUB>B</SUB>. Based on L<SUB>B</SUB>=3.8×10<SUP>9</SUP> cm derived
  from the relative displacements of the observed radio centroids, we
  find magnetic field strengths in excess of 1500 G at heights of 15,000
  km and as great as 1000 G at 25,000 km. By observing a given target
  region on several successive days, we would obtain observations at a
  variety of projection angles, thus enabling a better determination of
  L<SUB>B</SUB> and, ultimately, B(x,y,h). We compare coronal magnetic
  fields derived from our method with those derived from a potential
  extrapolation and find that the magnitudes of the potential field
  strengths are factors of 2 or more smaller than those derived from our
  method. This indicates that the sunspot field is not potential and that
  currents must be present in the corona. Alfvén speeds between 25,000
  and 57,000 km s<SUP>-1</SUP> are derived for the 1×10<SUP>6</SUP>
  K plasma at the centroids of the radio observing frequencies. Filling
  factors between 0.003 and 0.1 are derived for the 1×10<SUP>6</SUP>
  K plasma at the centroids of the radio observing frequencies.

---------------------------------------------------------
Title: Estimation of projection effect of CMEs from the onset time
    of shock-associated type III radio burst
Authors: Michalek, G.; Gopalswamy, N.; Reiner, M.; Yashiro, S.;
   Kaiser, M. L.; Howard, R. A.
2002ESASP.508..449M    Altcode: 2002soho...11..449M
  We present a new possibility to estimate the projection effects on CME
  measurements. We assume that (1) high energy electrons are produced at
  the shock front ahead of the CME, and (2) the radio burst starts when
  the shock reaches open field lines (~3 R<SUB>solar</SUB>). In other
  words, the onset time of the radio burst corresponds to the time when
  the CME leading edge reaches 3 R<SUB>solar</SUB>. It is well known
  that coronagraphic observations of halo CMEs are subject to projection
  effects. Fortunately, the Wind/WAVES observations of type III radio
  bursts associated with shock waves are free from projection effects. The
  difference between the onset times of CMEs and radio bursts should be
  strongly correlated with the position of CMEs on the Sun. We found
  this correlation and showed that it strongly depends on a period of
  solar activity and source location on the Sun. Particular linear fits
  to the considered scattered plots can be used to further determination
  of source location and projection of CMEs on the plane of sky.

---------------------------------------------------------
Title: A new possibility to estimate the width, source location and
    velocity of halo CMEs
Authors: Michalek, G.; Gopalswamy, N.; Yashiro, S.
2002ESASP.508..453M    Altcode: 2002soho...11..453M
  It is well known that the coronagraphic observations of halo CMEs are
  subject to projection effects. Viewing in the plane of the sky does not
  allow us to determine the crucial parameters defining geoeffectivness
  of CMEs, such as the velocity, width or source location. We assume
  that halo CMEs at the beginning phase of propagation have constant
  velocities, are symmetric and propagate with constant angular
  widths. Using these approximations and determining projected velocities
  and difference between times when CME appears on the opposite sides
  of the occultation disk we are able to get necessary parameters. We
  present consideration for the whole halo CMEs from SOHO/LASCO catalog
  until the end of 2000.

---------------------------------------------------------
Title: Interacting Coronal Mass Ejections and Solar Energetic
    Particles
Authors: Gopalswamy, N.; Yashiro, S.; Michałek, G.; Kaiser, M. L.;
   Howard, R. A.; Reames, D. V.; Leske, R.; von Rosenvinge, T.
2002ApJ...572L.103G    Altcode:
  We studied the association between solar energetic particle (SEP) events
  and coronal mass ejections (CMEs) and found that CME interaction is
  an important aspect of SEP production. Each SEP event was associated
  with a primary CME that is faster and wider than average CMEs and
  originated from west of E45°. For most of the SEP events, the primary
  CME overtakes one or more slower CMEs within a heliocentric distance of
  ~20 R<SUB>solar</SUB>. In an inverse study, we found that for all the
  fast (speed greater than 900 km s<SUP>-1</SUP>) and wide (width greater
  than 60°) western hemispheric frontside CMEs during the study period,
  the SEP-associated CMEs were ~4 times more likely to be preceded by
  CME interaction than the SEP-poor CMEs; i.e., CME interaction is a
  good discriminator between SEP-poor and SEP-associated CMEs. We infer
  that the efficiency of the CME-driven shocks is enhanced as they
  propagate through the preceding CMEs and that they accelerate SEPs
  from the material of the preceding CMEs rather than from the quiet
  solar wind. We also found a high degree of association between major
  SEP events and interplanetary type II radio bursts, suggesting that
  proton accelerators are also good electron accelerators.

---------------------------------------------------------
Title: Prominence Eruptions and CMEs: A Statistical Study
Authors: Gopalswamy, N.; Shimojo, M.; Yashiro, S.; Shibasaki, K.
2002AAS...200.3705G    Altcode: 2002BAAS...34..695G
  Prominence eruptions are thought to be an integral part of coronal mass
  ejections. However, recent statistical studies obtained conflicting
  conclusions regarding this relationship: a nearly one-to-one
  correspondence to a poor association. We revisited this problem using
  all the eruptive prominences detected automatically from the daily
  images obtained by the Nobeyama Radioheliograph. The images were
  made with a 10 min cadence so only slower eruptions could be detected
  from these images. During January 1996 to December 2001, there were
  226 prominence eruptions detected this way and 182 of them had white
  light observations from the Solar and Heliospheric Observatory (SOHO)
  mission. When we compared the radio and white light data, we found
  that 76 CMEs, while only 16 remaining 8 suggesting partial eruption. We
  conclude that there is good association between CMEs when the prominence
  eruptions have a radial component of the velocity is dominant.

---------------------------------------------------------
Title: Properties of coronal mass ejections and relationship with
    solar flares
Authors: Yashiro, S.; Gopalswamy, N.; Michalek, G.; Howard, R. A.
2002AAS...200.3704Y    Altcode: 2002BAAS...34..695Y
  Coronal mass ejections (CMEs) associated with flares are thought to
  be faster than those associated with filament eruptions. However,
  Hundhausen (1997) examined that the relationship between CME kinetic
  energy and X-ray flare peak intensity, and found that there is only
  a weak correlation. We have measured the speed, size, location,
  and acceleration of more than 4000 CMEs observed by the SOHO LASCO
  Coronagraph from January 1996 through December 2001, providing a good
  opportunity to revisit the relationship between CMEs and flares. We
  identified flare-CME pairs as follows: Since the field of view of the
  LASCO C2 coronagraph limited to heliocentric distances over 2 solar
  radii (Ro), we cannot obtain the CME start time accurately. So, we
  assume that the CMEs start from 1 Ro, and estimate the start time from
  their height-time trajectories. Then, we looked for CMEs that occurred
  within flare impulsive phase. This way, we found 239 flare-CME pairs. We
  found a weak correlation between the CME speed and flare X-ray peak
  flux (correlation coefficient = 0.52). When we isolated the limb events
  (based on the solar source of the CMEs), we found the correlation to
  be poorer (0.44). We compare our results with those of Hundhausen.

---------------------------------------------------------
Title: Interplanetary Radio Bursts
Authors: Gopalswamy, N.
2002AAS...200.4908G    Altcode: 2002BAAS...34..722G
  Radio bursts in the interplanetary (IP) medium are indicative of solar
  eruptions that expel shock-driving coronal material or energetic
  electron beams. Type II radio bursts originate from fast-mode MHD
  shocks driven by coronal mass ejections (CMEs). Type III bursts are
  produced by energetic electrons escaping along open magnetic field
  lines. Occasionally, type IV bursts are also observed in the near-Sun
  IP medium. Radio and Plasma Waves (WAVES) experiment on board the
  Wind spacecraft routinely observes these radio bursts at frequencies
  below 14 MHz since 1994. This new radio window in the 1-14 MHz band
  has helped us confirm several of the well known solar-terrestrial
  processes and discover new processes such as the nonthermal radio
  emission due to colliding CMEs. The IP type II bursts are indicative
  of faster and wider CMEs, which are important from a space weather
  point of view. There is also a high degree of association between
  solar energetic particles and type II radio bursts implying that the
  same shocks accelerate protons and electrons. I provide a summary of
  the recent results obtained using radio and white light data.

---------------------------------------------------------
Title: Relationship Between DH Type II Radio Bursts and Energetic
    Particle Events
Authors: Rosas, A. M.; Gopalswamy, N.; Kaiser, M. L.
2002AAS...200.3703R    Altcode: 2002BAAS...34Q.695R
  A comparison of 134 interplanetary type II bursts detected by the
  WIND/WAVES experiment in the 1-14 MHz range is made with the solar
  energetic particle (SEP) events. The study period is from 1996 to 2001,
  which is between minimum and slightly above maximum of the current solar
  cycle (23). We find that approximately 74% of the IP type II bursts are
  related to an energetic particle event. We are continuing to investigate
  the reasons why some interplanetary type II radio bursts do not have
  energetic particle events. A longitudinal distribution of the solar
  sources of these events will be used to discriminate between the SEP
  and non-SEP type II bursts. The study will be able to tell us whether
  electron accelerators are also proton accelerators. This research was
  supported by NASA. Travel to this meeting is partly supported by the
  SPD Studentship Award.

---------------------------------------------------------
Title: Influence of CME Interaction on Solar Proton Events During
    Cycle 23
Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Kaiser, M. L.;
   Howard, R. A.; Reames, D. V.; Leske, R. A.; Von Rosenvinge, T.
2002AGUSMSH41A..06G    Altcode:
  We studied the association between solar proton events and white-light
  coronal mass ejections (CMEs) that occurred during the solar cycle
  23 until November 2001. Each of the SEP events was associated with
  a large-scale primary CME, that were faster and wider than average
  CMEs. For most of the proton events, the primary CME overtakes one or
  more slower CMEs. In order to confirm this result, we examined the
  association and CME interaction and energetic proton events for all
  the fast (speed &gt; 900 km~s<SUP>-1</SUP>) and wide (width &gt; 60
  deg) western hemispheric and halo CMEs during the study period. CMEs
  with energetic protons are 3 times more likely to be preceded by CME
  interaction than those without. We conclude that CME interaction is an
  important aspect of SEP acceleration. We infer that CME-driven shocks
  accelerate SEPs from the material of the preceding CMEs rather than
  from the quiet solar wind.

---------------------------------------------------------
Title: New Measurements of 3-D Sunspot Coronal Magnetic Fields From
    Coordinated SOHO EUV and VLA Radio Observations
Authors: Brosius, J. W.; White, S. M.; Landi, E.; Cook, J. W.; Newmark,
   J. S.; Gopalswamy, N.; Lara, A.
2002AAS...200.0307B    Altcode: 2002BAAS...34..642B
  Three-dimensional sunspot coronal magnetograms were derived from
  coordinated extreme-ultraviolet (EUV) and radio observations of NOAA
  regions 8108 (N21E18 on 1997 November 18) and 8539 (N20W12 on 1999 May
  13). The EUV spectra and images, obtained with the Coronal Diagnostic
  Spectrometer (CDS) and the Extreme-ultraviolet Imaging Telescope (EIT)
  aboard the Solar and Heliospheric Observatory (SOHO) satellite, were
  used to derive the differential emission measure (DEM) and the plasma
  electron density for each spatial pixel (along each line of sight)
  within both regions. These were subsequently used to calculate maps
  of the expected thermal bremsstrahlung brightness temperature at the
  Very Large Array (VLA) radio observing frequencies of 1.4, 4.9, 8.4,
  and 15 GHz. The thermal bremsstrahlung maps reproduce neither the
  structure nor the intensity of the observed maps, and indicate that
  thermal gyroemission must dominate the observed radio emission. The
  radio observations were used to constrain the magnetic scale height and
  the gross temperature structure of the atmosphere. These, along with
  the DEM, electron density, and observed radio brightness temperature
  maps, were used to derive the temperature distribution of the coronal
  magnetic field strength B(T) that reproduced simultaneously the observed
  right-hand and left-hand circularly polarized emission at the radio
  observing frequencies for each spatial pixel in the images. Magnetic
  field strengths corresponding to 3rd harmonic gyroemission at 4.9 GHz
  (580 Gauss) are found in coronal plasmas at temperatures as high as
  3.2 MK, while magnetic field strengths corresponding to 3rd harmonic
  gyroemission at 15 GHz (1800 Gauss) are found in coronal plasmas at
  temperatures as high as 1.6 MK. B(T) was ultimately converted to B(h)
  and compared with extrapolations from photospheric magnetograms.

---------------------------------------------------------
Title: Evidence from Coronal Observations of Magnetic Field Structure
    in CMEs
Authors: Gopalswamy, N.
2002AAS...200.6509G    Altcode: 2002BAAS...34..752G
  The magnetic nature of coronal mass ejections has been inferred from
  the fact that they originate from closed magnetic field regions on
  the Sun such as active regions and filament regions. Although we have
  no direct measurement of the magnetic fields of CMEs, we can obtain
  useful information on the magnetic structure of CMEs from coronal
  observations at various wavelengths. The CME is a multithermal structure
  with temperatures ranging from a few kilokelvin to several megakelvin,
  so we need multi-wavelength observations to get a global picture of
  CMEs. A wide range of ground and space based instruments routinely
  observe CMEs. We present several examples of CMEs observed in X-ray,
  white light, EUV and radio wavelengths that help us understand the
  magnetic structure of CMEs.

---------------------------------------------------------
Title: Properties of coronal mass ejections observed by SOHO
Authors: Yashiro, S.; Gopalswamy, N.; Michalek, G.; St. Cyr, O. C.;
   Plunkett, S. P.; Howard, R. A.
2002AGUSMSH32A..03Y    Altcode:
  We report the characteristics of more than 4000 coronal mass ejections
  (CMEs) observed by the SOHO LASCO Coronagraph from January 1996
  through December 2001. We have measured the speed, size, location, and
  acceleration of each CME, and examined the annual variation of their
  distributions. All of CME measurements are shown in the online catalog
  (http://cdaw.gsfc.nasa.gov/). Using this CME catalog, we found that
  (1) almost of CMEs occurred around equator during the solar minimum,
  while CME appeared at all latitudes during the solar maximum. (2) the
  average speed increases toward solar maximum from 306 km/s to 500 km/s,
  and slightly decreases to 482 km/s in 2001. (3) The width distribution
  become wider toward solar maximum. These results are consistent with
  those of Solwind and Skylab.

---------------------------------------------------------
Title: Motion of an Eruptive Prominence in the Solar Corona
Authors: Filippov, B. P.; Gopalswamy, N.; Lozhechkin, A. V.
2002ARep...46..417F    Altcode:
  A model for the nonradial motion of an eruptive prominence in the solar
  corona is proposed. Such motions, which can sometimes be inaccessible
  to observation, result in an apparent break in the causal link between
  eruptive prominences and coronal mass ejections. The global magnetic
  field of the Sun governs coronal plasma motions. The complex structure
  of this field can form prominence trajectories that differ considerably
  from a simple vertical rise (i.e., radial motion). A solar filament is
  modeled as a current-carrying ring or twisted toroidal magnetic rope
  in equilibrium with the coronal magnetic field. The global field is
  described using two spherical harmonics. A catastrophic violation of the
  filament equilibrium followed by its rapid acceleration—eruption—is
  possible in this nonlinear system. The numerical solution of the
  equations of motion corresponds well to the eruption pattern observed
  on December 14, 1997.

---------------------------------------------------------
Title: Interplanetary radio emission due to interaction between two
    coronal mass ejections
Authors: Gopalswamy, Nat; Yashiro, Seiji; Kaiser, Michael L.; Howard,
   Russell A.; Bougeret, J. -L.
2002GeoRL..29.1265G    Altcode: 2002GeoRL..29h.106G
  We report on the detection of a new class of nonthermal radio
  emission due to the interaction between two coronal mass ejections
  (CMEs). The radio emission was detected by the Radio and Plasma Wave
  Experiment (WAVES) on board the Wind satellite, while the CMEs were
  observed by the white-light coronagraphs of the Solar and Heliospheric
  Observatory (SOHO) mission. There was no type II radio burst (metric or
  interplanetary) preceding the nonthermal emission. The radio emission
  occurred at a distance beyond 10 R<SUB>s</SUB> from the Sun, where the
  two CMEs came in contact. Using H-alpha and EUV images, we found that
  the two CMEs were ejected roughly along the same path. We argue that
  the nonthermal electrons responsible for the new type of radio emission
  were accelerated due to reconnection between the two CMEs and/or due
  to the formation of a new shock at the time of the collision between
  the two CMEs.

---------------------------------------------------------
Title: Influence of the aerodynamic drag on the motion of
    interplanetary ejecta
Authors: Vršnak, Bojan; Gopalswamy, Nat
2002JGRA..107.1019V    Altcode:
  A simple semi-empirical model for the motion of interplanetary ejecta is
  proposed to advance the prediction of their arrival times at Earth. It
  is considered that the driving force and the gravity are much smaller
  than the aerodynamic drag force. The interaction with the ambient solar
  wind is modeled using a simple expression for the acceleration $[\dot
  \upsilon \]$ = -γ(υ-w), where w = w(R) is the distance-dependent
  solar wind speed. It is assumed that the coefficient γ decreases
  with the heliocentric distance as γ = αR<SUP>-β</SUP>, where α
  and β are constants. The equation of motion is integrated numerically
  to relate the Earth transit time and the associated in situ velocity
  with the velocity of coronal mass ejection. The results reproduce well
  the observations in the whole velocity range of interest. The model
  values are compared with some other models in which the interplanetary
  acceleration is not velocity dependent, as well as with the model where
  the drag acceleration is quadratic in velocity $\[\dot \upsilon \]$
  = -γ<SUB>2</SUB>(υ - w)|υ - w|.

---------------------------------------------------------
Title: Colliding coronal mass ejections and particle acceleration
Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M.; Reames, D.;
   Howard, R.
2002cosp...34E1253G    Altcode: 2002cosp.meetE1253G
  Colliding Coronal Mass Ejections (CMEs) have important implications to
  a number of physical processes in the near-Sun interplanetary medium:
  Shock propagation, particle acceleration and solar wind composition. We
  present statistical results on large solar energetic particle events,
  associated CMEs and CME interaction during solar cycle 23. We show
  that most of the large SEP events are preceded by CME interaction. As
  an inverse study, we identified all the fast and wide front side CMEs
  from the western hemisphere and examined the SEP association and
  CME interaction. We found that fast and wide CMEs interacting with
  preceding CMEs are more likely to be associated with SEPs. We discuss
  the implications of the statistical results to the understanding of
  particle acceleration by CME-driven shocks.

---------------------------------------------------------
Title: Propagation of coronal mass ejections from Sun to 1 AU
Authors: Manoharan, P.; Gopalswamy, N.; Yashiro, S.; Howard, R.
2002cosp...34E2699M    Altcode: 2002cosp.meetE2699M
  We report on the study of propagation characteristics of a large number
  of CMEs over the entire range of Sun-Earth distance. Using white-light
  (LASCO) and interplanetary scintillation (IPS) observations, we
  investigate the radial variation of the speed of CMEs. In the case
  of fast CMEs (initial speed 800 kms-1 ), speed declines slowly with
  distance (VcmeR-a where a0.05-0.1) within about 100 Rsun . Beyond this
  distance, the speed declines as VcmeR-b where b0.5 - 1. The evolution
  of size of CMEs with distance, LcmeR, suggests a pressure balance
  maintained between the CME and ambient solar wind at distances greater
  than 50 Rsun . We also report the detection of interaction between
  fast and slow CMEs outside the LASCO field of view. The interaction
  signature is seen as an unusual enhancement in the density turbulence.

---------------------------------------------------------
Title: Space Weather Study Using Combined Coronagraphic and in
    Situ Observations
Authors: Gopalswamy, N.
2002swsm.conf...39G    Altcode:
  Coronal mass ejections (CMEs) play an important role in space
  weather studies because of their ability to cause severe geoeffects,
  such as magnetic storms. Shocks driven by CMEs may also accelerate
  solar energetic particles. Prediction of the arrival of these CMEs is
  therefore of crucial importance for space weather applications. After
  a brief review of the prediction models currently available, a
  description of an empirical model to predict the 1 AU arrival CMEs
  is provided. This model was developed using two-point measurements:
  (i) the initial speeds and onset times of Earth-directed CMEs obtained
  by white-light coronagraphs, and (ii) the corresponding interplanetary
  CME speeds and onset times at 1 AU obtained in situ. The measurements
  yield an empirical relationship between the interplanetary acceleration
  faced by the CMEs and their initial speeds, which forms the basis
  of the model. Use of archival data from spacecraft in quadrature is
  shown to refine the acceleration versus initial speed relationship,
  and hence the prediction model. A brief discussion on obtaining the
  1-AU speed of CMEs from their initial speeds is provided. Possible
  improvements to the prediction model are also suggested.

---------------------------------------------------------
Title: Relation Between Coronal Mass Ejections and their
    Interplanetary Counterparts
Authors: Gopalswamy, N.
2002stma.conf..157G    Altcode:
  Our current knowledge on coronal mass ejections (CMEs) comes from
  two spatial domains: the near-Sun (up to 30 solar radii) region
  remote-sensed by coronagraphs and the geospace and beyond where in situ
  observations are made by spacecraft. Comparing observations from these
  two domains has helped us understand the propagation and evolution of
  CMEs through the interplanetary (IP) medium and develop an empirical
  model to predict the 1-AU arrival of CMEs. In this paper, we review
  the available information on the relation between CMEs and their IP
  counterparts. In particular, we concentrate on issues related to the
  prediction of the arrival of ICMEs in the geospace. We discuss the
  solar sources of the three largest geomagnetic storms of year 2000 and
  compare the predicted and observed arrival times of the associated CMEs.

---------------------------------------------------------
Title: CMEs: observations of all kinds
Authors: Gopalswamy, Nat
2002ocnd.confE..13G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Properties of Narrow Coronal Mass Ejections Observed with LASCO
Authors: Yashiro, S.; Gopalswamy, N.; Howard, R.
2002cosp...34E2602Y    Altcode: 2002cosp.meetE2602Y
  More than 4500 coronal mass ejections (CMEs) have been observed
  with SOHO LASCO coronagraph from January 1996 to December 2001. We
  have measured properties of all these CMEs and published them in an
  online catalog. In this paper, we describe the properties of narrow
  CMEs (width &lt; 20 deg.). We investigated 675 narrow CMEs from the
  catalog and found that (1) the fraction of narrow CMEs increases from
  5% to 15% towards solar maximum, (2) the average speed of the narrow
  CMEs is higher than that of the wide ones, (3) the maximum speed of
  narrow CMEs (1141 km/s) is much smaller than that of the wide CMEs
  (2604 km/s). We also found that the wide CMEs are likely to have the
  well known three-part structure, but narrow ones do not. Wide CMEs
  can be explained as due to the expansion of flux tubes, but the narrow
  CMEs seem to be mass flows in vertical flux tubes (streamers).

---------------------------------------------------------
Title: Statistical Properties of Radio-Rich Coronal Mass Ejections
Authors: Gopalswamy, N.; Yashiro, S.; Michalek, G.; Kaiser, M. L.;
   Howard, R. A.; Bougeret, J. -L.
2002stma.conf..169G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Origin of coronal streamer distention
Authors: Gopalswamy, N.; Shimojo, M.; Lu, W.; Yashiro, S.; Shibasaki,
   K.; Howard, R.
2002cosp...34E1257G    Altcode: 2002cosp.meetE1257G
  Distention of coronal streamers is considered to be one of the
  pre-eruption evolution of coronal mass ejections (CMEs), although how
  mass is added to the streamers is poorly understood. During our study
  of eruptive prominences and their relation to CMEs, we observed a large
  number of prominences associated with significant changes in the helmet
  streamers overlying the prominences. We used the white light images of
  the corona obtained by the Solar and Heliospheric Mission's Large Angle
  and Spectrometric Coronagraph images and the microwave images from the
  Nobeyama radioheliograph in Japan. We found that the streamer distention
  is associated with prominence eruption with mostly horizontal motion
  (parallel to the solar limb) or with eruptive prominences with most of
  the mass falling back to the solar surface. We suggest that the physical
  process which activates the prominences also add mass to the streamers.

---------------------------------------------------------
Title: Variability of solar eruptions during cycle 23
Authors: Gopalswamy, N.; Nunes, S.; Yashiro, S.; Howard, R.
2002cosp...34E1260G    Altcode: 2002cosp.meetE1260G
  Nearly 5000 coronal mass ejections (CMEs) were observed by the Solar
  and Heliospheric Observatory from the minimum to maximum of the current
  solar cycle (19962001). We have measured and cataloged the properties
  of all these CMEs. We have studied the variation of mean and median
  speeds and the rate of CMEs (averaged over Carrington rotations)
  as a function time. We compare the CME rate with those of other
  energetic solar events such as interplanetary type II bursts, solar
  energetic particle (SEP) events and metric type II bursts. This study
  is useful in identifying the phases of the solar cycle which show rapid
  variability. CMEs associated with radio bursts and SEPs belong to a
  separate group characterized by high speed and large width. We discuss
  the solar cycle variability of this energetic group in comparison with
  the general population of CMEs.

---------------------------------------------------------
Title: An empirical model to predict the 1-AU arrival of
    interplanetary shocks
Authors: Gopalswamy, N.; Lara, A.; Manoharan, P.; Howard, R.
2002cosp...34E1256G    Altcode: 2002cosp.meetE1256G
  We describe an empirical model to predict the 1-AU arrival of
  interplanetary shocks of solar origin. This model is an extension of
  Gopalswamy et al.'s [2001] empirical CME arrival model based on an
  effective acceleration acting on the CMEs as they propagate through the
  interplanetary medium. We measured the properties of a large number
  IP shocks, their solar sources and associated CMEs. Using in situ
  observations from Wind and ACE, we obtained the physical conditions
  upstream and down stream of the shock. Combining the shock data with the
  known piston-shock relation, we estimate the shock arrival times. We
  compare the estimated and actual arrival times of shocks to determine
  the error in our shock-arrival estimates. Reference: Gopalswamy, N.,
  A. Lara, S. Yashiro, M. L. Kaiser, and R. A. Howard, Predicting the
  1-AU Arrival Times of Coronal Mass Ejections, J. Geophys. Res., 106,
  29,207, 2001

---------------------------------------------------------
Title: Phenomena Associated with EIT Waves
Authors: Thompson, B.; Biesecker, D.; Gopalswamy, N.
2002cosp...34E2672T    Altcode: 2002cosp.meetE2672T
  We discuss phenomena associated with "EIT Wave" transients. "EIT
  Waves" are propagating disturbances first observed in SOHO/EIT EUV
  images. However, a number of studies have been conducted to determine
  their relationship to other observations, using data from a variety
  of instruments. These phenomena include coronal mass ejections,
  flares, EUV/SXR dimmings,chromospheric waves, Moreton waves, solar
  energetic particle events, energetic electron events, and radio
  signatures. Although the occurrence of many phenomena correlate with the
  appearance of EIT waves, it is difficult to infer which associations are
  causal. The presentation will include a discussion of the correlation
  statistics of these phenomena.

---------------------------------------------------------
Title: Solar eruptions and long wavelength radio bursts: The 1997
    May 12 event
Authors: Gopalswamy, N.; Kaiser, M. L.
2002AdSpR..29..307G    Altcode:
  We report on the cause of the 1997 May 12 type II bursts observed by
  ground based and space-based radio instruments. We estimate the fast
  mode speed in the corona as a function of heliocentric distance to
  identify the regions where fast mode shocks can be driven by CMEs. We
  find that both the coronal and the interplanetary type II bursts can
  be explained by shocks driven by the same CME at two different spatial
  domains. The fast mode speed in the corona has a peak at a heliocentric
  distance of ∼ 3 R<SUB>⊙</SUB> which does not allow the coronal shock
  wave to propagate beyond this distance. When the CME continues to travel
  beyond the fast mode peak, another shock forms in the interplanetary
  medium where the fast mode speed falls sufficiently. From the radio
  observations we can infer that the plane of the sky speed of the CME
  is smaller than the space speed by at least a factor of 2, consistent
  with the location of the eruption at N21 W08. The inferred CME speed
  is also consistent with previous deprojected speed estimates.

---------------------------------------------------------
Title: A Statistical Study for Two Classes of CMEs
Authors: Moon, Y.; Choe, G.; Park, Y.; Yang, G.; Wang, H.; Goode,
   P.; Yashiro, S.; Gopalswamy, N.
2001AGUFMSH12B0747M    Altcode:
  MacQueen and Fisher (1983) noted the existence of two classes of CMEs;
  flare-associated CMEs show the highest speeds with little acceleration,
  wheras eruption-associated ones exhibit large accelerations. A
  statistical study has been performed to examine the bimodality of CMEs
  using the CME catalogue based on SOHO/LASCO observations from 1996 to
  2000 by Yashiro and Michalek (2001). In the catalogue, we have used the
  speed and acceleration data obtained from height-time plots with 2nd
  order fits. We present the histogram of CME speed, the histogram of
  CME acceleration, and their speed-acceleration diagram. We have also
  conducted the same analysis for two different sets of data which have
  both time and spatial association with GOES solar flares and filaments
  activities (e.g., disappearing filaments), respectively. The filament
  data were collected from the NGDC and Big Bear Solar Observatory. Major
  results from this study are as follows. (1) The speed histogram for
  all the CMEs has a major peaks near 300km/s but does not show any
  double peaks. (2) Their acceleration histogram has a strong peak near
  zero, even for the two data sets associated with solar flares and
  filaments. (3) The number of CMEs with deceleration is comparable to
  that of CMEs with acceleration. (4) Their acceleration distribution
  has a maximum near zero regardless of their speed. (5) The ratio
  of flare-associated ones to all the CMEs increases with CME speed,
  wheras the ratio of filament-associated ones decreases. Finally we
  compare our results with previous ones and discuss their implications
  on the bimodality of CMEs.

---------------------------------------------------------
Title: Interplanetary Acceleration of Coronal Mass Ejections:
    Comparison between numerical simulations and observations
Authors: Lara, A.; Gonzalez-Esparza, A.; Perez-Tijerina, E.; Santillan,
   A.; Gopalswamy, N.
2001AGUFMSH11D..10L    Altcode:
  For a set of 50 Coronal Mass Ejections (CMEs) observed with the Large
  Angle and Spectrometric COrongraph (LASCO) on board of the SOlar and
  Heliospheric Observatory (SOHO) mission, we estimate the density and
  measure the sky-plane speed at 18 solar radii (R<SUB>sun</SUB>). We
  feed these parameters to a one dimensional, single fluid, hydrodynamic
  model to simulate the CME propagation from 18 R<SUB>sun</SUB> to one
  AU, and iteratively adjust the initial temperature and ambient solar
  wind speed using in situ measurements by the Wind mission prior to
  and during the ICMEs that pair with the white-light CMEs. Following
  the evolution of the nose of the ejecta we are able to construct an
  acceleration model for the simulated ICMEs. We compare and discuss the
  simulated acceleration profile with the observed mean acceleration in
  order to obtain a general ICME acceleration model.

---------------------------------------------------------
Title: CME Interactions Near the Sun
Authors: Gopalswamy, N.
2001AGUFMSH11D..01G    Altcode:
  The phenomenon of interaction between coronal mass ejections in the
  near-Sun interplanetary medium is surveyed using data from SOHO and
  Wind missions. Long wavelength radio data (1-14 MHz) reveal CME-CME
  and CME-shock interactions. CME interactions may result in change of
  CME trajectories or merger ("cannibalism"). Typically, slower CMEs
  are overtaken by faster CMEs. Occasionally, multiple interactions
  are observed. Solar cycle variation of the CME interaction rate will
  be presented based on a careful examination of all the available CME
  data from SOHO. Finally, consequences of the CME interaction in the
  interplanetary medium will be discussed briefly. Research supported
  by NASA, AFOSR and NSF.

---------------------------------------------------------
Title: Interacting CMEs and Solar Energetic Particles
Authors: Gopalswamy, N.; Yashiro, S.; von Rosenvinge, T. T.; Leske, R.
2001AGUFMSH12A0735G    Altcode:
  We examined the solar sources of a set of large solar energetic
  particle (SEP) events with mixed (impulsive + gradual) abundance
  signatures. The SEP events were detected by the Solar Isotope
  Spectrometer (SIS) on board the Advanced Composition Explorer (ACE)
  spacecraft. For each of the SEP events, we identified a "primary"
  coronal mass ejection (CME), detected by the Solar and Heliospheric
  observatory (SOHO). Then we examined a set of CMEs preceding the
  primary CME, potentially interacting with the primary CME in the
  near-Sun interplanetary medium. Twenty events from a list of 27
  recently compiled von Rosenvinge et al. (Proc. ICRC 2001, p. 3136)
  overlapped with SOHO observations. Preliminary results indicate that
  a large majority of the primary CMEs were preceded by slower CMEs,
  suggesting that CME interaction may result in abundance enhancements
  in the source material. Research supported by NASA and AFOSR.

---------------------------------------------------------
Title: Characteristics of coronal mass ejections associated with
    long-wavelength type II radio bursts
Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.;
   Bougeret, J. -L.
2001JGR...10629219G    Altcode:
  We investigated the characteristics of coronal mass ejections (CMEs)
  associated with long-wavelength type II radio bursts in the near-Sun
  interplanetary medium. Type II radio bursts in the decameter-hectometric
  (DH) wavelengths indicate powerful MHD shocks leaving the inner
  solar corona and entering the interplanetary medium. Almost all of
  these bursts are associated with wider and faster than average CMEs. A
  large fraction of these radio-rich CMEs were found to decelerate in the
  coronagraph field of view, in contrast to the prevailing view that most
  CMEs display either constant acceleration or constant speed. We found a
  similar deceleration for the fast CMEs (speed&gt;900kms<SUP>-1</SUP>)
  in general. We suggest that the coronal drag could be responsible
  for the deceleration, based on the result that the deceleration has a
  quadratic dependence on the CME speed. About 60% of the fast CMEs were
  not associated with DH type II bursts, suggesting that some additional
  condition needs to be satisfied to be radio-rich. The average width
  (66°) of the ratio-poor, fast CMEs is much smaller than that (102°) of
  the radio-rich CMEs, suggesting that the CME width plays an important
  role. The special characteristics of the radio-rich CMEs suggest
  that the detection of DH radio bursts may provide a useful tool in
  identifying the population of geoeffective CMEs.

---------------------------------------------------------
Title: Predicting the 1-AU arrival times of coronal mass ejections
Authors: Gopalswamy, Nat; Lara, Alejandro; Yashiro, Seiji; Kaiser,
   Mike L.; Howard, Russell A.
2001JGR...10629207G    Altcode:
  We describe an empirical model to predict the 1-AU arrival of
  coronal mass ejections (CMEs). This model is based on an effective
  interplanetary (IP) acceleration described by Gopalswamy et al. [2000b]
  that the CMEs are subject to, as they propagate from the Sun to
  1 AU. We have improved this model (1) by minimizing the projection
  effects (using data from spacecraft in quadrature) in determining the
  initial speed of CMEs, and (2) by allowing for the cessation of the
  interplanetary acceleration before 1 AU. The resulting effective IP
  acceleration was higher in magnitude than what was obtained from CME
  measurements from spacecraft along the Sun-Earth line. We evaluated the
  predictive capability of the CME arrival model using recent two-point
  measurements from the Solar and Heliospheric Observatory (SOHO), Wind,
  and ACE spacecraft. We found that an acceleration cessation distance
  of 0.76 AU is in reasonable agreement with the observations. The
  new prediction model reduces the average prediction error from 15.4
  to 10.7 hours. The model is in good agreement with the observations
  for high-speed CMEs. For slow CMEs the model as well as observations
  show a flat arrival time of ~4.3 days. Use of quadrature observations
  minimized the projection effects naturally without the need to assume
  the width of the CMEs. However, there is no simple way of estimating the
  projection effects based on the surface location of the Earth-directed
  CMEs observed by a spacecraft (such as SOHO) located along the Sun-Earth
  line because it is impossible to measure the width of these CMEs. The
  standard assumption that the CME is a rigid cone may not be correct. In
  fact, the predicted arrival times have a better agreement with the
  observed arrival times when no projection correction is applied to the
  SOHO CME measurements. The results presented in this work suggest that
  CMEs expand and accelerate near the Sun (inside 0.7 AU) more than our
  model supposes; these aspects will have to be included in future models.

---------------------------------------------------------
Title: Momentum Coupling Between Coronal Mass Ejections and the
    Solar Wind
Authors: Chen, J.; Gopalswamy, N.; Yashiro, S.
2001AGUFMSH12A0740C    Altcode:
  The interaction of coronal mass ejections (CMEs) and the ambient
  solar wind plays a critically important role in determining the CME
  acceleration near the Sun and the subsequent evolution through the
  interplanetary medium. In particular, the speed and the magnetic
  field of associated magnetic clouds at 1 AU are dependent on the
  momentum transfer from the CME to the solar wind (SW) during the
  transit. Theoretically, because of the high magnetic Reynold's number,
  turbulent drag has been used to model the integrated drag (retarding
  or accelerating depending on the velocity differential) force on
  CMEs exerted by the SW (Chen 1996). The drag coefficient has been
  previously estimated to be of order unity using a 2-D MHD simulation
  of flux-rope interactions with an ambient magnetizid plasma consistent
  with SW conditions near 1 AU (Cargill et al. 1996). Such treatments
  posit that the momentum coupling between a flux rope and the ambient
  plasma is proportional to (V-V<SUB>sw</SUB>)<SUP>2</SUP>, where V
  is the speed of the flux rope and V<SUB>sw</SUB> is the ambient SW
  speed. Recently, Gopalswamy et al. (2001) found that the observationally
  inferred drag force is approximately quadratic in CME speed, based on
  61 decelerating CME events. In this paper, we examine specific events
  using LASCO data and determine the drag coefficient: for each event,
  we measure the speed-height profile and the minor radius at the leading
  edge; then using a model of the coronal density and SW outflow speed,
  estimate the drag coefficient. Work supported by ONR and NASA. Chen,
  J., JGR, 101, 27499, 1996 Cargill, P. J., J. Chen, D. S. Spicer,
  and S. T. Zalesak, JGR, 101, 4855, 1996. Gopalswamy, N., S. Yashiro,
  M. L. kaiser, R. A. Howard, and J.-L. Bougeret, in press, JGR, 2001.

---------------------------------------------------------
Title: Limb Flares, CMEs &amp; Metric Type II Radio Bursts: A New
    Statistical Study
Authors: Hammer, D.; Gopalswamy, N.; Yashiro, S.; Nunes, S.;
   Michalek, G.
2001AGUFMSH42A0767H    Altcode:
  Past studies of the relationship between flares, coronal mass
  ejections(CMEs), and metric typeII radio bursts have been accomplished
  without the significantly larger and more detailed CME database that
  is available today through SOHO/LASCO observations. This abundance
  of CME data allows us to more accurately study the flare-CME-typeII
  relationship thereby permitting better substantiated conclusions. Our
  study examines the relationship between solar flares and their
  correlated CMEs and metric typeII bursts by sampling all (approximately
  900) X-ray/H-alpha limb flares occurring between January 1996 and June
  2001. Flare events are collected from Solar Geophysical Data (SGD)
  and flare location is confirmed with SOHO EIT, Yokhoh SXT, and Nobeyama
  Radioheliograph movies. All correlated CMEs are confirmed in LASCO/EIT
  movies and their parameters are obtained from the CSPSW/NRL maintained,
  SOHO/LASCO CME catalog. Metric typeII burst data are also obtained from
  SGD and from the websites of several individual observatories (Potsdam,
  Hiraiso, Learmonth, Izmiran, and Nancay). We will present statistical
  analysis on the occurrences between all three solar phenomena and how
  these relationships change when flare, CME, and typeII parameters
  change. Additionally, we will analyze how the data relates to past
  results (e.g. CME Speed vs. Flare Intensity, CME Speed vs. TypeII
  Occurrence, TypeII Onset - Flare Start vs. Starting Frequency, etc.). We
  will also present relationships between CME-flare-typeII onset times
  in addition to solar cycle effects.

---------------------------------------------------------
Title: Numerical Study on the Acceleration of Coronal Mass Ejections
    in the Interplanetary Medium
Authors: Gonzalez-Esparza, A.; Lara, A.; Perez-Tijerina, E.; Santillan,
   A.; Gopalswamy, N.
2001AGUFMSH11D..09G    Altcode:
  Recently Gopalswamy et al. [2000] studied observations of ICMEs by
  WIND spacecraft and correlated these observations with CMEs detected
  previously by SOHO coronographs. They found that the Sun-Earth mean
  acceleration of these events was approximately proportional to their
  initial speeds, and they suggest that this result could be used for
  space weather forecasting. In this work we perform a parametric study
  of several CME like disturbances propagating in two different ambient
  winds using a one dimensional, single fluid, hydrodynamic model, to
  study the kinematics of the CME fronts near the Sun to 1 AU. These
  1-D simulations of interplanetary disturbances have shown to be very
  useful to understand the basic physical aspects of the injection and
  heliospheric evolution of these phenomena. In this work we explore how
  the CME acceleration and transit time from near the Sun to 1 AU varies
  depending on the CME initial conditions and the ambient solar wind.

---------------------------------------------------------
Title: Statistical analysis of coronal shock dynamics implied by
    radio and white-light observations
Authors: Reiner, M. J.; Kaiser, M. L.; Gopalswamy, N.; Aurass, H.;
   Mann, G.; Vourlidas, A.; Maksimovic, M.
2001JGR...10625279R    Altcode:
  For 19 solar eruptive events we present a statistical comparison of the
  shock dynamics derived from the measured frequency drift rates of metric
  and decametric-hectometric (D-H) type II radio bursts with the dynamics
  of the associated coronal mass ejection (CME). We find that the shock
  speed parameters derived from the D-H type II radio emissions generated
  in the high corona (~2-4R<SUB>solar</SUB>R<SUB>solar</SUB>=696,000km)
  are well correlated with the corresponding CME plane-of-the-sky
  speeds (correlation coefficient=0.71). On the other hand, we find
  no obvious correlation between the shock speed parameters derived
  from the metric type II radio bursts, generated in the middle
  corona (1.4-2R<SUB>solar</SUB>), and the corresponding CME speeds
  (correlation coefficient=-0.07). In general, we also find no clear
  correlation between the shock speed parameters derived from the
  metric type II bursts and the D-H radio emissions (correlation
  coefficient=0.3). However, the metric type II radio bursts sometimes
  include a second component that is possibly related to the D-H radio
  emissions. These statistical comparisons of the shock dynamics, implied
  by the observed metric and D-H type II frequency drift rates, provide
  further evidence for two distinct coronal shocks. Our statistical
  analyses are proceeded by two specific examples that illustrate the
  methodology used in this study.

---------------------------------------------------------
Title: A multi-wavelength study of solar coronal-hole regions showing
    radio enhancements
Authors: Moran, T.; Gopalswamy, N.; Dammasch, I. E.; Wilhelm, K.
2001A&A...378.1037M    Altcode:
  We observed 17 GHz microwave-enhanced regions in equatorial coronal
  holes (ECH) together with extreme-ultraviolet (EUV), far-ultraviolet
  (FUV) and visible emissions in a search for temperature increases which
  might explain the bright spots in radio wavelengths. The ultraviolet
  (UV) observations span a wide range of formation temperatures (8000 K
  to 630 000 K). Increased UV emission was observed at the approximate
  location of the radio enhancements, but unlike the radio brightening,
  the UV emission did not exceed the mean quiet sun level. However,
  there were two observations showing increased Hα brightness in radio
  enhancements above mean quiet sun levels. No Hα bright spots were
  detected in ECHs outside of radio enhancement regions. The ECH Hα
  bright spots were caused by bright fibrils, bright points and a lack
  of dark fibrils. Since the 17 GHz and Hα enhancements are co-spatial,
  have equal integrated normalized enhanced emission and brightness
  temperatures, the observations suggest that the radio enhancements
  are caused by increased fibril radio emission. In addition, increased
  Fe XII EUV emission was recorded at the location of some well-defined
  radio enhancements, which were the bases of coronal plumes. Since the
  radio brightness temperature is much lower than the Fe xii formation
  temperature, the radio and EUV enhancements are likely both related
  to the presence of concentrated magnetic flux, but do not arise from
  the same physical layer.

---------------------------------------------------------
Title: Near-Sun and near-Earth manifestations of solar eruptions
Authors: Gopalswamy, N.; Lara, A.; Kaiser, M. L.; Bougeret, J. -L.
2001JGR...10625261G    Altcode:
  We compare the near-Sun and near-Earth manifestations of solar
  eruptions that occurred during November 1994 to June 1998. We
  compared white-light coronal mass ejections, metric type II radio
  bursts, and extreme ultraviolet wave transients (near the Sun) with
  interplanetary (IP) signatures such as decameter-hectometric type II
  bursts, kilometric type II bursts, IP ejecta, and IP shocks. We did a
  two-way correlation study to (1) look for counterparts of metric type
  II bursts that occurred close to the central meridian and (2) look for
  solar counterparts of IP shocks and IP ejecta. We used data from Wind
  and Solar and Heliospheric Observatory missions along with metric radio
  burst data from ground-based solar observatories. Analysis shows that
  (1) most (93%) of the metric type II bursts did not have IP signatures,
  (2) most (80%) of the IP events (IP ejecta and shocks) did not have
  metric counterparts, and (3) a significant fraction (26%) of IP shocks
  were detected in situ without drivers. In all these cases the drivers
  (the coronal mass ejections) were ejected transverse to the Sun-Earth
  line, suggesting that the shocks have a much larger extent than the
  drivers. Shocks originating from both limbs of the Sun arrived at Earth,
  contradicting earlier claims that shocks from the west limb do not reach
  Earth. These shocks also had good type II radio burst association. We
  provide an explanation for the observed relation between metric,
  decameter-hectometric, and kilometric type II bursts based on the fast
  mode magnetosonic speed profile in the solar atmosphere.

---------------------------------------------------------
Title: Introduction to special section: Global picture of solar
    eruptive events
Authors: Gopalswamy, Nat
2001JGR...10625135G    Altcode:
  This introduction highlights some of the scientific results reported
  in this special section on solar eruptive events and provides a brief
  description of issues related to the new results. Most of these papers
  grew out of the coordinated data analysis workshop held at the Goddard
  Space Flight Center during April 27-30, 1999, and the subsequent
  International Conference on Solar Eruptive Events held at the Catholic
  University of America, Washington, D. C. during March 6-9, 2000.

---------------------------------------------------------
Title: X-ray Ejecta, White-Light CMEs and a Coronal Shock Wave
Authors: Gopalswamy, N.; Cyr, O. C. St.; Kaiser, M. L.; Yashiro, S.
2001SoPh..203..149G    Altcode:
  We report on a coronal shock wave inferred from the metric type II
  burst of 13 January 1996. To identify the shock driver, we examined
  mass motions in the form of X-ray ejecta and white-light coronal mass
  ejections (CMEs). None of the ejections could be considered fast (&gt;
  400 km s<SUP>−1</SUP>) events. In white light, two CMEs occurred in
  quick succession, with the first one associated with X-ray ejecta near
  the solar surface. The second CME started at an unusually large height
  in the corona and carried a dark void in it. The first CME decelerated
  and stalled while the second one accelerated, both in the coronagraph
  field of view. We identify the X-ray ejecta to be the driver of the
  coronal shock inferred from metric type II burst. The shock speed
  reported in the Solar Geophysical Data (1000-2000 km s<SUP>−1</SUP>)
  seems to be extremely large compared to the speeds inferred from
  X-ray and white-light observations. We suggest that the MHD fast-mode
  speed in the inner corona could be low enough that the X-ray ejecta
  is supermagnetosonic and hence can drive a shock to produce the type
  II burst.

---------------------------------------------------------
Title: Non-radial motion of eruptive filaments
Authors: Filippov, B. P.; Gopalswamy, N.; Lozhechkin, A. V.
2001SoPh..203..119F    Altcode:
  We develop a simple model to explain the non-radial motion of eruptive
  solar filaments under solar minimum conditions. The global magnetic
  field is derived from the first and third components of the spherical
  harmonic expansion of a magnetic scalar potential. The filament is
  modeled as a toroidal current located above the mid-latitude polarity
  inversion line. We investigate the stability of the filament against
  changes in the filament current and attempt to explain the non-radial
  motion and acceleration of the eruptive filament. We also discuss the
  limitations of this model.

---------------------------------------------------------
Title: Band-splitting of coronal and interplanetary type II
    bursts. I. Basic properties
Authors: Vršnak, B.; Aurass, H.; Magdalenić, J.; Gopalswamy, N.
2001A&A...377..321V    Altcode:
  Patterns analogous to the band-splitting of metric type II bursts are
  found in a number of type II bursts observed in the dekameter-kilometer
  wavelength range. A similarity of morphological and frequency-time
  characteristics of two emission components are indicative of a
  common source. Relative frequency splits span in the range Delta
  f/f=0.05-0.6. At radial distances between 2 and 4 R<SUB>sun</SUB> only
  small splits around 0.1 can be found. In the interplanetary space the
  relative split on average increases with the radial distance, whereas
  the inferred shock velocity decreases. In three events extrapolations
  of the split components point to the base and the peak of the jump
  in the local plasma frequency caused by the associated shock passage
  at 1 AU. This is suggestive of the plasma radiation from the regions
  upstream and downstream of the shock. Adopting this interpretation, one
  finds that the drop of Delta f/f at 2-4 R<SUB>sun</SUB> is congruent
  with the Alfvén velocity maximum expected there. The split increase
  and the velocity decrease at larger distances can be explained as a
  consequence of declining Alfvén speed in the interplanetary space.

---------------------------------------------------------
Title: Estimation of projection effect of CMEs from onset time of
    type III radio bursts.
Authors: Michalek, G.; Gopalswamy, N.; Reiner, M.; Yashiro, S.
2001AGUSM..SH22A05M    Altcode:
  We present a new possibility to estimate the projection effect on CME
  measurements. We assume that (1) high energy electrons are produced
  at the shock front ahead of the CME, and (2) the radio burst starts
  when the shock reaches open field lines ( ~ 3 R). In other words,
  the onset time of the radio burst corresponds to the time when the
  CME leading edge reaches 3 R. It is well known that white light
  observations of halo CMEs with the LASCO coronagraph are subject
  projection effects. Fortunately, the Wind/WAVES experiment observations
  of type III radio burst associated with shock waves are free from
  this problems. The difference between onset times of CMEs and radio
  bursts should be strongly correlated with the position of CMEs on the
  Sun. We try to determine this correlation and use it to estimate the
  real starting position of CMEs.

---------------------------------------------------------
Title: Development of SOHO/LASCO CME Catalog and Study of CME
    Trajectories
Authors: Yashiro, S.; Gopalswamy, N.; St. Cyr, O. C.; Lawrence, G.;
   Michalek, G.; Young, C. A.; Plunkett, S. P.; Howard, R. A.
2001AGUSM..SH31C10Y    Altcode:
  We present a catalog of coronal mass ejections (CMEs) based on
  SOHO/LASCO observations. This catalog covers the period from
  1998 October to the present time. For each of the observed CMEs,
  the catalog contains the following information: LASCO C2 appearance
  time, Central Position Angle, Angular Width, height-time plots with
  Linear (constant speed) and 2nd order (constant acceleration) fits and
  corresponding speeds, and acceleration. The catalog will be open to the
  public via World Wide Web after proper validation. Using a preliminary
  version of this data set, we investigated the CME trajectories based
  on linear and quadratic fits to the data points. We estimated the
  error in the computed trajectories as follows: Generally speaking,
  the error in each height measurement depends on the quality of the
  CME feature that is tracked. So we grouped the observations into 5
  classes based on the quality of the features on a 1-5 scale: Poor,
  Fair, Typical, Good, and Excellent. For a CME with a clear leading
  edge (excellent quality), the error in the measured height is small
  (5% of the measured height). On the other hand, for a CME with a
  ragged leading edge (poor quality), the error becomes larger (20% of
  the measured height). Based on this scheme, we assigned errorbars to
  the measured heights and then performed a weighted least-squares fit
  to the height-time trajectories. We found that for 90% of the CMEs,
  the linear (constant speed) fit is preferable. For the remaining 10%,
  quadratic fit (constant acceleration) is better than the linear fit.

---------------------------------------------------------
Title: Lasco CME Speeds and Metric Type II Radio Bursts
Authors: Hammer, D.; Gopalswamy, N.; Yashiro, S.
2001AGUSM..SH22C01H    Altcode:
  We are using images obtained with LASCO to study correlations between
  CME parameters and the occurrence of metric Type II radio bursts. In
  particular, contemporary theories, based on SMM data, suggest a strict
  causal relationship between CME speeds and the production of metric
  Type II's. We will analyze how this relationship unfolds for Type II
  events occurring since the beginning of the LASCO mission in 1996,
  and look for solar cycle effects. We will also examine the speed of
  metric Type II's in comparison to LASCO derived CME speeds.

---------------------------------------------------------
Title: Origin and Early Evolution of Coronal Mass Ejections
Authors: Gopalswamy, N.
2001AGUSM..SH61A01G    Altcode:
  Simultaneous observations at multiple wavelengths over a large field
  of view have dramatically improved our understanding of coronal
  mass ejections. Extreme ultraviolet and soft X-ray observations
  reveal the source regions of Earth-directed CMEs. Microwave and
  H-alpha observations provide information on the cool components of the
  CMEs. Radio observations at long decametric and hectometric wavelengths
  trace CME-driven shock waves that just enter into the interplanetary
  medium. This paper summarizes recent findings on CMEs using SOHO, Yohkoh
  and Wind observations and discusses how near-Sun CME observations are
  useful in interpreting transient events in the inner heliosphere.

---------------------------------------------------------
Title: Measurements of 3-D Sunspot Coronal Magnetic Fields From
    Coordinated SOHO EUV and VLA Radio Observations
Authors: Brosius, J. W.; Landi, E.; Cook, J. W.; Newmark, J.;
   Gopalswamy, N.; Lara, A.
2001AGUSM..SH32C02B    Altcode:
  Three-dimensional sunspot coronal magnetograms were derived from
  coordinated extreme-ultraviolet (EUV) and radio observations of
  NOAA region 8108 (N21 E18) on 1997 November 18. The EUV spectra
  and images, obtained with the Coronal Diagnostic Spectrometer (CDS)
  and the Extreme-ultraviolet Imaging Telescope (EIT) aboard the Solar
  and Heliospheric Observatory (SOHO) satellite, were used to derive
  differential emission measure (DEM) distributions for each spatial
  pixel (i.e., along each line of sight) of the region's images. These
  were subsequently used to calculate maps of the expected thermal
  bremsstrahlung brightness temperature at the Very Large Array
  (VLA) radio observing frequencies of 4.9 and 8.4 GHz. The thermal
  bremsstrahlung maps reproduce neither the structure nor the intensity
  of the observed maps, and indicate that thermal gyroemission must
  also contribute to the observed radio emission. Under the assumptions
  of a monotonic increase in temperature and a monotonic decrease in
  magnetic field strength with height above the sunspot, we derived
  the temperature distribution of the coronal magnetic field strength
  that reproduced simultaneously the observed right-hand and left-hand
  circularly polarized radio emission at 4.9 and 8.4 GHz for each
  spatial pixel in the sunspot maps. This was done by placing harmonics
  of the radio observing frequencies in appropriate plasma temperature
  intervals, integrating along the line of sight, and iterating until
  a solution was obtained. Magnetic field strengths corresponding to
  3rd harmonic gyroemission at 4.9 GHz (580 Gauss) are found in coronal
  plasmas at temperatures as high as 2.2*E<SUP>6</SUP> K, while magnetic
  field strengths corresponding to 2nd harmonic gyroemission at 8.4 GHz
  (1500 Gauss) are found in coronal plasmas at temperatures as high as
  1.1*E<SUP>6</SUP> K.

---------------------------------------------------------
Title: An Observational Study of Solar Coronal-hole Regions Showing
    Radio Enhancements
Authors: Moran, T. G.; Gopalswamy, N.; Dammash, I.; Wilhelm, K.
2001AGUSM..SH41A13M    Altcode:
  We observed 17~GHz microwave-enhanced regions in equatorial coronal
  holes (ECH) together with extreme-ultraviolet (EUV), far-ultraviolet
  (FUV) and visible emissions in a search for temperature increases which
  might explain the bright spots in radio wavelengths. The ultraviolet
  (UV) observations span a wide range of formation temperatures (8000~K
  to 630 000~K). Increased UV emission was observed at the approximate
  location of the radio enhancements, but unlike the radio brightening,
  the UV emission did not exceed the mean quiet sun level. However,
  there were two observations showing increased Hα brightness in radio
  enhancements above mean quiet sun levels. No Hα bright spots were
  detected in ECHs outside of radio enhancement regions. The ECH Hα
  bright spots were caused by bright fibrils, bright points and a lack
  of dark fibrils. Since the 17~GHz and Hα enhancements are co-spatial,
  have equal integrated normalized enhanced emission and brightness
  temperatures, the observations suggest that the radio enhancements
  are caused by increased fibril radio emission. In addition, increased
  Fe xii EUV emission was recorded at the location of some well-defined
  radio enhancements, which were the bases of coronal plumes. Since the
  radio brightness temperature is much lower than the Fe xii formation
  temperature, the radio and EUV enhancements are likely both related
  to the presence of concentrated magnetic flux, but do not arise from
  the same physical layer.

---------------------------------------------------------
Title: Acceleration and Deceleration of CMEs Associated with Long
    Wavelength Radio Bursts
Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Howard, R.
2001AGUSM..SH31C07G    Altcode:
  Type II radio bursts in the Decameter-Hectometric (DH) wavelengths
  indicate powerful MHD shocks leaving the inner corona. Almost all
  of these bursts are associated with massive and faster-than-average
  coronal mass ejections (CMEs). A particularly interesting characteristic
  of these DH CMEs is that they are predominantly decelerating in the
  coronagraph field of view. In the past, it was thought that there are
  mainly constant speed and accelerating CMEs. We discuss the possible
  explanations for the CME deceleration in the near-Sun interplanetary
  medium. Research supported by NASA, NSF and Air Force Office of
  Scientific Research

---------------------------------------------------------
Title: Testing the Empirical CME Arrival Model Using Earth Directed
    Events
Authors: Lara, A.; Gopalswamy, N.; Dasso, S.; Yashiro, S.
2001AGUSM..SH61A05L    Altcode:
  An empirical model to predict the arrival of coronal mass ejections at
  1 AU was developed recently (Gopalswamy et al. 2000), based on SOHO
  and Wind observations. The model was further improved by correcting
  for the intrinsic projection effects on CME initial speed. This
  correction was performed using archival data from Helios-1, Pioneer
  Venus Orbiter and P78-1 (Solwind) spacecraft which were in quadrature
  so that the projection effects were minimal. In this work we use the
  corrected CME arrival model to predict the travel time of a large
  set of Earth directed halo CMEs observed by SOHO/LASCO from January
  1997 to December 2000. We search for interplanetary signatures around
  the predicted arrival times. In particular, one of the most commonly
  observed characteristics of interplanetary CMEs (ICME) is their low
  temperature with respect to the ambient (fast and slow) solar wind. We
  search for low temperature regions from in situ data obtained by
  Wind, ACE, and IMP8 spacecraft, as a proxy to the ICMEs. Finally, we
  compare the predicted CME arrival times with the detected ICME times
  and perform a statistical analysis of the errors in the predicted time.

---------------------------------------------------------
Title: Radio Signatures of Coronal Mass Ejection Interaction:
    Coronal Mass Ejection Cannibalism?
Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.;
   Bougeret, J. -L.
2001ApJ...548L..91G    Altcode:
  We report the first detection at long radio wavelengths of interaction
  between coronal mass ejections (CMEs) in the interplanetary medium. The
  radio signature is in the form of intense continuum-like radio emission
  following an interplanetary type II burst. At the time of the radio
  enhancement, coronagraphic images show a fast CME overtaking a slow
  CME. We interpret the radio enhancement as a consequence of shock
  strengthening when the shock ahead of the fast CME plows through the
  core of the preceding slow CME. The duration of the radio enhancement
  is consistent with the transit time of the CME-driven shock through the
  core of the slow CME. As a consequence of the interaction, the core of
  the slow CME changed its trajectory significantly. Based on the emission
  characteristics of the radio enhancement, we estimate the density of
  the core of the slow CME to be ~4×10<SUP>4</SUP> cm<SUP>-3</SUP>. The
  CME interaction has important implications for space weather prediction
  based on halo CMEs: some of the false alarms could be accounted for
  by CME interactions. The observed CME interaction could also explain
  some of the complex ejecta at 1 AU, which have unusual composition.

---------------------------------------------------------
Title: Early life of coronal mass ejections
Authors: Gopalswamy, N.; Thompson, B. J.
2000JASTP..62.1457G    Altcode: 2000JATP...62.1457G
  Coronal mass ejections (CMEs) are large-scale magnetized plasma
  structures ejected from closed magnetic field regions of the Sun. White
  light coronagraphic observations from ground and space have provided
  extensive information on CMEs in the outer corona. However, our
  understanding of the solar origin and early life of CMEs is still in
  an elementary stage because of lack of adequate observations. Recent
  space missions such as Yohkoh and Solar and Heliospheric Observatory
  (SOHO) and ground-based radioheliographs at Nobeyama and Nancay have
  accumulated a wealth of information on the manifestations of CMEs
  near the solar surface. We review some of these observations in
  an attempt to relate them to what we already know about CMEs. Our
  discussion relies heavily on non-coronagraphic data combined with
  coronagraphic data. Specifically, we discuss the following aspects of
  CMEs: (i) coronal dimming and global disk signatures, (ii) non-radial
  propagation during the early phase, (iii) Photospheric magnetic field
  changes during CMEs, and (iv) acceleration of fast CMEs. The relative
  positions and evolution of coronal dimming, arcade formation, prominence
  eruption will be discussed using specific events. The magnitude and
  spatial extent of CME acceleration may be an important parameter that
  distinguishes fast and slow CMEs.

---------------------------------------------------------
Title: Soft X-Ray and Gyroresonance Emission above Sunspots
Authors: Nindos, A.; Kundu, M. R.; White, S. M.; Shibasaki, K.;
   Gopalswamy, N.
2000ApJS..130..485N    Altcode:
  Using Yohkoh SXT and Nobeyama 17 GHz data, we have studied the soft
  X-ray and microwave emission above several stable, large sunspots
  near central meridian passage. Our study confirms the well-known fact
  that soft X-ray emission is depressed above sunspots. It also shows
  that the distribution of their soft X-ray intensity is not uniform;
  usually the darkest pixels are associated with the umbra or the far
  edges of the leading part of the penumbra while the following part
  of the penumbra may contain higher intensity pixels associated with
  brighter loops. For the first time, we present a systematic survey
  of the temperatures and emission measures of the soft X-ray material
  above sunspots. Sunspots always contain the lowest temperatures and
  emission measures in the active regions. The mean umbral temperature
  is 1.8×10<SUP>6</SUP> K, and the mean penumbral temperature is
  2.4×10<SUP>6</SUP> K. The mean umbral and penumbral emission measures
  are logEM=26.60 cm<SUP>-5</SUP> and logEM=27.00 cm<SUP>-5</SUP>,
  respectively. The differences between the umbral and penumbral plasma
  temperatures are physically significant. The higher penumbral values
  imply that the loops associated with the penumbrae are generally hotter
  and denser than the loops associated with the umbrae. The highest
  sunspot temperatures and emission measures are still lower than the
  average active region parameters but higher than the quiet-Sun plasma
  parameters. The coronal radiative energy loss rate above the umbrae
  is 15% higher than the radiative loss rate of the quiet-Sun plasma
  but a factor of 8.3 lower than the typical active region radiative
  loss rate. The radio emission comes from the gyroresonance mechanism,
  and, as expected, it is sensitive to the magnetic field rather than
  the soft X-ray-emitting plasma.

---------------------------------------------------------
Title: Correction to “Change in photospheric magnetic flux during
    coronal mass ejections”
Authors: Lara, Alejandro; Gopalswamy, Nat; DeForest, Craig
2000GeoRL..27.1863L    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Microwave Enhancement in Coronal Holes: Statistical Propeties
Authors: Gopalswamy, N.; Shibasaki, K.; Salem, M.
2000JApA...21..413G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: SOHO and radio observations of a CME shock wave
Authors: Raymond, John C.; Thompson, Barbara J.; St. Cyr, O. C.;
   Gopalswamy, Nat; Kahler, S.; Kaiser, M.; Lara, A.; Ciaravella, A.;
   Romoli, M.; O'Neal, R.
2000GeoRL..27.1439R    Altcode:
  A 1200 km s<SUP>-1</SUP> Coronal Mass Ejection was observed with the
  SOHO instruments EIT, LASCO and UVCS on June 11, 1998. Simultaneously,
  Type II radio bursts were observed with the WAVES experiment aboard
  the Wind spacecraft at 4 MHz and by ground-based instruments at metric
  wavelengths. The density in the shock wave implied by the higher
  frequency is close to that inferred from the SOHO/UVCS experiment. The
  drift rates of the Type II radio bursts suggest shock speeds lower than
  the speed derived from SOHO observations. The SOHO/UVCS spectrum shows
  enhanced emission in lines of O<SUP>5+</SUP> and Si<SUP>11+</SUP>,
  consistent with modest compression in an MHD shock.

---------------------------------------------------------
Title: Radio-rich solar eruptive events
Authors: Gopalswamy, N.; Kaiser, M. L.; Thompson, B. J.; Burlaga,
   L. F.; Szabo, A.; Lara, A.; Vourlidas, A.; Yashiro, S.; Bougeret,
   J. -L.
2000GeoRL..27.1427G    Altcode:
  We report on the analysis of a large number of solar eruptive events
  that produced radio emission in the dekameter-hectometric (DH) radio
  window (1-14 MHz), newly opened by the Wind/WAVES experiment. The
  distinguishing characteristics of coronal mass ejections (CMEs)
  associated with the DH type II radio bursts are larger-than-average
  width and speed. Flares of all sizes (X-ray importance B to X) occurring
  at all longitudes were associated with the DH type II bursts and
  CMEs. We found a global enhancement in EUV over an area much larger than
  the flaring active region in the beginning many events. A comparison
  between the ‘Shock Associated’ events and microwave bursts shows
  that at least half of the events do not have temporal relation. A
  majority of the DH type II bursts were associated with IP shocks
  and kilometric type II bursts. In particular, we found a very close
  relationship between the kilometric type II bursts and the IP shocks.

---------------------------------------------------------
Title: Change in photospheric magnetic flux during coronal mass
    ejections
Authors: Lara, Alejandro; Gopalswamy, Nat; DeForest, Craig
2000GeoRL..27.1435L    Altcode:
  We report on the variations of photospheric magnetic flux during
  coronal mass ejections (CMEs). Using magneograms from the SOHO/MDI
  instrument, we have computed the magnetic flux of 7 active regions and
  one disappearing filament region associated with CMEs. When we plotted
  the flux versus time over a period of few days before, during and after
  the CME event, we found changes in the mean magnetic flux per pixel
  (∼4 arcsec²), ranging from ∼0.4 to ∼3.1 × 10<SUP>17</SUP> Mx,
  in structures of size smaller than the active region. Flare onsets
  and the filament disappearance clearly occurred during periods of
  significant variations in the measured magnetic flux.

---------------------------------------------------------
Title: An Empirical Model to Predict the Arrival of CMEs at 1 AU
Authors: Gopalswamy, N.; Lara, A.; Kaiser, M. L.
2000SPD....31.0283G    Altcode: 2000BAAS...32..825G
  We describe an empirical model to predict the arrival of coronal mass
  ejections (CMEs) at 1 AU based on the initial speed of CMEs obtained
  from coronagraphs. The only input needed in this model is the measured
  initial speed of CMEs. This model is based on an effective acceleration
  that CMEs are subject to, as they propagate from the Sun to 1 AU. We
  developed this model based on the two-point measurements made from
  SOHO and Wind spacecraft. We validate our model based on older data
  obtained by Helios-1, P78-1, Pioneer Venus Orbiter and Solar Maximum
  Mission spacecraft. We discuss the merits and limitations of this
  model. Research supported by the National Research Council, NSF,
  and NASA.

---------------------------------------------------------
Title: Magnetic Evolution and Eruptive Events Associated to Active
    Region 8210
Authors: Lara, A.; Gopalswamy, N.
2000SPD....31.1403L    Altcode: 2000BAAS...32..846L
  We present a study of one active region with high flare and CME
  activity. From April 27 to May 5, 1998, AR8210 was crossing the south
  solar hemisphere and produced many flares, and at least five CMEs
  were related to activity in this region, some of them were homologous
  events. We use magnetograms from the Michelson Doppler Imager (MDI)
  experiment on board of the Solar Heliospheric Observatory (SOHO) to
  construct the time series of the photospheric magnetic elements. We
  compute the line of sight magnetic flux over the entire active region,
  and over localized areas inside the active region in which activity
  was detected in EUV (198 Angstroms) maps from the Extreme ultraviolet
  Imaging Telescope (EIT) on board of SOHO. We found considerable
  differences between the positive and negative fluxes computed
  over the entire region, the mean negative flux per pixel was 50 to
  100 % greater than the positive flux. Using microwave polarization
  measures from Nobeyama Radio Heliograph, we were able to confirm such
  differences. The magnetic flux computed over AR8210 also showed a
  considerable increasing phase when the flare and CME activity of the
  region was increasing. On the other hand, we found that in general,
  flares occur during a maximum phase in the magnetic flux computed over
  localized subregions and that the major changes on this magnetic flux
  seems to be related to CMEs. Finally we discuss the flare and CME
  production, with special emphasis in the homologous events.

---------------------------------------------------------
Title: Observations of the 24 September 1997 Coronal Flare Waves
Authors: Thompson, B. J.; Reynolds, B.; Aurass, H.; Gopalswamy, N.;
   Gurman, J. B.; Hudson, H. S.; Martin, S. F.; St. Cyr, O. C.
2000SoPh..193..161T    Altcode:
  We report coincident observations of coronal and chromospheric `flare
  wave' transients in association with a flare, large-scale coronal
  dimming, metric radio activity and a coronal mass ejection. The two
  separate eruptions occurring on 24 September 1997 originate in the
  same active region and display similar morphological features. The
  first wave transient was observed in EUV and Hα data, corresponding
  to a wave disturbance in both the chromosphere and the solar corona,
  ranging from 250 to approaching 1000 km s<SUP>−1</SUP> at different
  times and locations along the wavefront. The sharp wavefront had a
  similar extent and location in both the EUV and Hα data. The data did
  not show clear evidence of a driver, however. Both events display a
  coronal EUV dimming which is typically used as an indicator of a coronal
  mass ejection in the inner corona. White-light coronagraph observations
  indicate that the first event was accompanied by an observable coronal
  mass ejection while the second event did not have clear evidence of a
  CME. Both eruptions were accompanied by metric type II radio bursts
  propagating at speeds in the range of 500-750 km s<SUP>−1</SUP>,
  and neither had accompanying interplanetary type II activity. The
  timing and location of the flare waves appear to indicate an origin
  with the flaring region, but several signatures associated with coronal
  mass ejections indicate that the development of the CME may occur in
  concert with the development of the flare wave.

---------------------------------------------------------
Title: Space VLBI at Low Frequencies
Authors: Jones, D. L.; Allen, R.; Basart, J.; Bastian, T.; Blume, W.;
   Bougeret, J. -L.; Dennison, B.; Desch, M.; Dwarakanath, K.; Erickson,
   W.; Farrell, W.; Finley, D.; Gopalswamy, N.; Howard, R.; Kaiser,
   M.; Kassim, N.; Kuiper, T.; MacDowall, R.; Mahoney, M.; Perley, R.;
   Preston, R.; Reiner, M.; Rodriguez, P.; Stone, R.; Unwin, S.; Weiler,
   K.; Woan, G.; Woo, R.
2000aprs.conf..265J    Altcode: 2000astro.ph..3120J
  At sufficiently low frequencies, no ground-based radio array will
  be able to produce high resolution images while looking through
  the ionosphere. A space-based array will be needed to explore the
  objects and processes which dominate the sky at the lowest radio
  frequencies. An imaging radio interferometer based on a large number
  of small, inexpensive satellites would be able to track solar radio
  bursts associated with coronal mass ejections out to the distance
  of Earth, determine the frequency and duration of early epochs of
  nonthermal activity in galaxies, and provide unique information about
  the interstellar medium. This would be a “space-space" VLBI mission,
  as only baselines between satellites would be used. Angular resolution
  would be limited only by interstellar and interplanetary scattering.

---------------------------------------------------------
Title: Structure of a Large low-Latitude Coronal Hole
Authors: Bromage, B. J. J.; Alexander, D.; Breen, A.; Clegg, J. R.;
   Del Zanna, G.; DeForest, C.; Dobrzycka, D.; Gopalswamy, N.; Thompson,
   B.; Browning, P. K.
2000SoPh..193..181B    Altcode:
  Coronal holes on the Sun are the source of high-speed solar wind
  streams that produce magnetic disturbances at the Earth. A series
  of multi-wavelength, multi-instrument observations obtained during
  the 1996 `Whole Sun Month' campaign examined a large coronal hole in
  greater detail than ever before. It appeared on the Sun in August, and
  extended from the north pole to a large active region in the southern
  hemisphere. Its physical and magnetic structure and subsequent evolution
  are described.

---------------------------------------------------------
Title: Radial Evolution and Turbulence Characteristics of a Coronal
    Mass Ejection
Authors: Manoharan, P. K.; Kojima, M.; Gopalswamy, N.; Kondo, T.;
   Smith, Z.
2000ApJ...530.1061M    Altcode:
  We investigate a coronal mass ejection (CME) associated with an
  X3.9 solar flare that occurred on 1992 June 25. This long-duration
  event showed a system of large postflare loops at the activity site
  throughout the period of the enhanced X-ray emission. The drift rate of
  the metric type IV radio burst observed near the X-ray maximum suggests
  the speed of the ejecta to be ~350 km s<SUP>-1</SUP> at heights &lt;=2
  solar radii. The solar proton intensities, in the energy range 1-100
  MeV observed in the interplanetary medium, show gradual-decay profiles
  lasting for more than two days and suggest CME-driven acceleration near
  the Sun. The inference on the spatial and kinematical characteristics
  of the propagating CME in the inner heliosphere (0.2-1 AU) is primarily
  based on the interplanetary scintillation observations at 327 MHz,
  obtained from the Ooty Radio Telescope and the Solar-Terrestrial
  Environment Laboratory. The scintillation data show the deceleration
  of propagating disturbance speed, V<SUB>CME</SUB>~R<SUP>-0.8</SUP>,
  in the interplanetary medium. The speeds obtained from the radio and
  scintillation measurements also suggest that the coronal shock may not
  be directly related to the interplanetary shock. The size of the CME in
  the interplanetary medium seems to follow a simple scaling with distance
  from the Sun, indicating the pressure balance maintained between the
  ejecta and the ambient solar wind. The density turbulence spectrum of
  the plasma carried by the propagating disturbance seems to be flat,
  Φ<SUB>N<SUB>e</SUB>(IPD)</SUB>~κ<SUP>-2.8</SUP>, also having a small
  dissipative scale length, S<SUB>i(IPD)</SUB>&lt;=5 km. The spectrum is
  significantly different from that of high-speed flow from coronal holes
  and low-speed wind originating above closed-field coronal streamers.

---------------------------------------------------------
Title: The ALFA Medium Explorer Mission
Authors: Jones, D. L.; Allen, R. J.; Basart, J. P.; Bastian, T.;
   Blume, W. H.; Bougeret, J. -L.; Dennison, B. K.; Desch, M. D.;
   Dwarakanath, K. S.; Erickson, W. C.; Farrell, W.; Finley, D. G.;
   Gopalswamy, N.; Howard, R. E.; Kaiser, M. L.; Kassim, N. E.; Kuiper,
   T. B. H.; MacDowall, R. J.; Mahoney, M. J.; Perley, R. A.; Preston,
   R. A.; Reiner, M. J.; Rodriguez, P.; Stone, R. G.; Unwin, S. C.;
   Weiler, K. W.; Woan, G.; Woo, R.
2000AdSpR..26..743J    Altcode:
  The frequency range below a few tens of MHz is unexplored with high
  angular resolution due to the opacity of Earth's ionosphere. An
  interferometer array in space providing arcminute angular resolution
  images at frequencies of a few MHz would allow a wide range of
  problems in solar, planetary, galactic, and extragalactic astronomy
  to be attacked. These include the evolution of solar radio emissions
  associated with shocks driven by coronal mass ejections and searches
  for coherent radio emission from supernova remnants and relativistic
  jets. In addition, it is likely that unexpected objects or emission
  processes will be discovered by such an instrument, as has always
  happened when high resolution astronomical observations first
  become possible in a new region of the electromagnetic spectrum. The
  Astronomical Low Frequency Array (ALFA) mission will consist of 16
  identical small satellites forming an aperture synthesis array. The
  satellites will cover the surface of a spherical region. ~100 km
  in diameter, thus providing good aperture plane coverage in all
  directions simultaneously. The array will operate in two modes: 1)
  “snapshot” imaging of strong, rapidly changing sources such as
  solar radio bursts and 2) long-term aperture synthesis observations
  for maximum sensitivity, high dynamic range imaging. In both cases a
  large number of array elements is needed

---------------------------------------------------------
Title: Time Evolution of Microwave and Hard X-ray Spectral Indexes
Authors: Lara, A.; Gopalswamy, N.
2000ASPC..206..355L    Altcode: 2000hesp.conf..355L
  No abstract at ADS

---------------------------------------------------------
Title: The Catholic University of America, Institute for Astrophysics
    and Computational Sciences, Department of Physics, Washington,
    District of Columbia 20064. Report for the period Sep 1998 - Sep 1999.
Authors: Gopalswamy, N.
2000BAAS...32...32G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Astronomical Low Frequency Array: A Proposed Explorer
    Mission for Radio Astronomy
Authors: Jones, D.; Allen, R.; Basart, J.; Bastian, T.; Blume, W.;
   Bougeret, J. -L.; Dennison, B.; Desch, M.; Dwarakanath, K.; Erickson,
   W.; Finley, D.; Gopalswamy, N.; Howard, R.; Kaiser, M.; Kassim, N.;
   Kuiper, T.; MacDowall, R.; Mahoney, M.; Perley, R.; Preston, R.;
   Reiner, M.; Rodriguez, P.; Stone, R.; Unwin, S.; Weiler, K.; Woan,
   G.; Woo, R.
2000GMS...119..339J    Altcode: 2000ralw.conf..339J
  A radio interferometer array in space providing high dynamic range
  images with unprecedented angular resolution over the broad frequency
  range from 0.03 - 30 MHz will open new vistas in solar, terrestrial,
  galactic, and extragalactic astrophysics. The ALFA interferometer
  will image and track transient disturbances in the solar corona
  and interplanetary medium - a new capability which is crucial
  for understanding many aspects of solar-terrestrial interaction
  and space weather. ALFA will also produce the first sensitive,
  high-angular-resolution radio surveys of the entire sky at low
  frequencies. The radio sky will look entirely different below about
  30 MHz. As a result, ALFA will provide a fundamentally new view of
  the universe and an extraordinarily large and varied science return.

---------------------------------------------------------
Title: Commission 10: Solar Activity: (Activite Solaire)
Authors: Ai, G.; Benz, A.; Dere, K. P.; Engvold, O.; Gopalswamy, N.;
   Hammer, R.; Hood, A.; Jackson, B. V.; Kim, I.; Marten, P. C.; Poletto,
   G.; Rozelot, J. P.; Sanchez, A. J.; Shibata, K.; van Driel-Geztelyi, L.
2000IAUTA..24...67A    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Type II Solar Radio Bursts
Authors: Gopalswamy, N.
2000GMS...119..123G    Altcode: 2000ralw.conf..123G
  Solar radio bursts of type II are thought to be caused by MHD shock
  waves propagating through the corona and interplanetary medium. They
  are identified as slowly drifting features in the dynamic spectra
  recorded by ground based and spaceborne radio instruments. The
  radio emission itself occurs as a final step in a series of physical
  processes: initiation of the shock, particle acceleration, generation
  of plasma waves and finally, conversion of the plasma waves into
  electromagnetic waves. Type II bursts play an important role in
  understanding the Sun-Earth connection, because of their association
  with flares and coronal mass ejections (CMEs). Images of type II
  bursts made by radioheliographs are crucial to understand the physical
  relationship between shocks, CMEs and solar flares. Observations of
  a new type of coronal waves by the EIT instrument on board the SOHO
  mission and long-decametric and hectometric type II bursts by the
  WIND/WAVES experiment have added new dimensions to the study of type
  II radio bursts. In this review, I summarize the basic properties and
  associated solar activities of type II bursts and discuss some of the
  current issues.

---------------------------------------------------------
Title: Shock Wave and EUV Transient During a Flare
Authors: Gopalswamy, N.; Kaiser, M. L.; Sato, J.; Pick, Monique
2000ASPC..206..351G    Altcode: 2000STIN...0032759G
  A metric type II burst and a 'brow' type enhancement in EUV were
  observed during the hard X-ray flare of 1997 April 15 from a newly
  emerging region, AR 8032. The position of the type II burst obtained
  from the Nancay radioheliograph coincided with the EUV transient. The
  type II burst and the EUV transient were in the equatorial streamer
  region to the north of the flaring region. This observation suggests
  that the EUV transient may be the manifestation of the MHD shock
  responsible for the type II burst.

---------------------------------------------------------
Title: Structure and Dynamics of the Corona Surrounding an Eruptive
    Prominence
Authors: Gopalswamy, N.; Hanaoka, Y.; Hudson, H. S.
2000AdSpR..25.1851G    Altcode:
  We report on the 1997 December 14 prominence eruption event that was
  accompanied by eruptive signatures in X-rays, EUV and white light:
  coronal dimming, X-ray arcade formation , X-ray brightenings, EUV
  eruption, and a white light CME. The data used were obtained by
  the Nobeyama Radioheliograph, Yohkoh Soft X-ray Telescope (SXT) and
  SOHO/LASCO and EIT. We identified various substructures of the eruption
  and their inter-relationships. We found that the pre-disruption swelling
  of the equatorial streamer was caused by the outward displacement of
  the coronal material around the prominence location. The dynamical
  behaviors of the CME and the accompanying eruptive prominence seem to
  be very different

---------------------------------------------------------
Title: Interplanetary acceleration of coronal mass ejections
Authors: Gopalswamy, N.; Lara, A.; Lepping, R. P.; Kaiser, M. L.;
   Berdichevsky, D.; St. Cyr, O. C.
2000GeoRL..27..145G    Altcode:
  Using an observed relation between speeds of CMEs near the Sun
  and in the solar wind, we determine an “effective” acceleration
  acting on the CMEs. We found a linear relation between this effective
  acceleration and the initial speed of the CMEs. The acceleration is
  similar to that of the slow solar wind in magnitude. The average solar
  wind speed naturally divides CMEs into fast and slow ones. Based on
  the relation between the acceleration and initial speed, we derive an
  empirical model to predict the arrival of CMEs at 1 AU.

---------------------------------------------------------
Title: Multi-wavelength Signatures of Coronal Mass Ejection
Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Thompson, B. J.;
   Plunkett, S.
1999spro.proc..207G    Altcode:
  We report on the near-surface and outer coronal manifestations of the
  1998 January 25 coronal mass ejection (CME) using white light, EUV,
  X-ray and hectometric radio data which reveal the three dimensional
  structure and long term evolution of the CME. We find that (i) the
  substructures of the CME (prominence core, cavity, frontal structure
  and the arcade formation) are clearly observed in X-ray and EUV
  wavelengths. (ii) The filament heats up early on and is observed as
  a backbone in X-rays. (iii) The filament also expands considerably
  as it erupts. (iv) The CME is observed through direct leading edge
  signature as well as through dimming process in X-rays and in EUV.

---------------------------------------------------------
Title: 17 GHz Mode Coupling in the Solar Corona
Authors: Lara, A.; Gopalswamy, N.; Pérez-Enríquez, R.; Shibasaki, K.
1999spro.proc...83L    Altcode:
  We studied the development of microwave polarization of a group
  of active regions for a period of 10 days during April, 1993 using
  data obtained by the Nobeyama radioheliograph. The observed sense
  of polarization at 17 GHz changed with the active region position on
  the solar disk. This change of polarization can be explained by the
  mode coupling theory according to which a weak coupling between the
  ordinary and extraordinary electromagnetic modes takes place when the
  radiation crosses a region of transverse magnetic field and results in
  a polarization reversal. Since the strength of the mode coupling depends
  on the physical parameters (and their gradients) of the quasi-transverse
  region, observations of polarization changes can be used to obtain key
  values of the magnetic field and field gradient in the active region
  corona. Using the intensity and polarization images of active regions,
  we found that the coupling constant is typically &gt; 10<SUP>3</SUP>
  corresponding to a weak coupling regime. We determined the mean
  value of the transition frequency to be ~ 5.3 × 10<SUP>11</SUP>
  Hz, below which the weak coupling effect is important. For all the
  active regions studied in this paper, there seems to be a similarity
  in the position on the solar disk where the mode coupling effects
  become important. The polarization reversal always occurred when the
  active regions were farther than the 500 arc sec mark from the disk
  center. Using this fact and extrapolated photospheric magnetic field
  we are able to estimate heights of both the quasi-transverse layer
  and the source region. Assuming a value of ~ 70 G, we obtain a value
  of 2.2 × 10<SUP>4</SUP> km for the Q-T layer height.

---------------------------------------------------------
Title: Solar Physics with Radio Observations
Authors: Bastian, T. S.; Gopalswamy, N.; Shibasaki, K.
1999spro.proc.....B    Altcode:
  Radio observations contribute a unique perspective on the many physical
  phenomena, which occur on the Sun. From thermal bremsstrahlung emission
  in the quiet solar atmosphere and filaments, to thermal gyroresonance
  emission in strongly magnetized solar active regions, to the nonthermal
  emission from MeV electrons accelerated in flares, observations of radio
  emission provide a powerful probe of physical conditions on the Sun and
  provide an additional means of understanding the myriad phenomena which
  occur there. Moreover, radio observing techniques have led the way in
  developing and exploiting Fourier synthesis imaging techniques. The
  Nobeyama Radioheliograph, commissioned in June, 1992, soon after the
  launch of Yohkoh satellite in August, 1991, is the most powerful,
  solar-dedicated Fourier synthesis in the world, now capable of imaging
  the full disk of the Sun simultaneously at frequencies of 17 and 34
  GHz, with an angular resolution as much as 10" and 5", respectively,
  and with a time resolution as fine as 100 msec. Between 27-30 October,
  1998, the Nobeyama Radio Observatory and the National Astronomical
  Observatory of Japan hosted the Nobeyama Symposium on Solar Physics
  with Radio Observations, an international meeting bringing more than
  sixty participants together at the Seisenryo Hotel in Kiyosato, for a
  meeting devoted to reviewing recent progress in outstanding problems
  in solar physics. Emphasis was placed on radio observations and,
  in particular, radio observations from the very successful Nobeyama
  Radioheliograph. These results were compared and contrasted with those
  that have emerged from the Yohkoh mission. In addition, looking forward
  to the next solar maximum, new instruments, upgrades, and collaborative
  efforts were discussed. The result is the more than seventy invited
  and contributed papers that appear in this volume.

---------------------------------------------------------
Title: The Astronomical Low Frequency Array (ALFA): Imaging from Space
Authors: Gopalswamy, N.; Kaiser, M. L.; Jones, D. L.; Alfa Team
1999spro.proc..447G    Altcode:
  The ALFA mission is a proposed astronomical observatory in space to
  make high resolution radio images at frequencies below the ionospheric
  cutoff (~ 20 MHz). This multi-satellite interferometric array will
  image solar as well as non-solar phenomena in the frequency range 0.03
  - 30 MHz. In this paper, we provide an overview of the ALFA mission,
  with particular emphasis on solar studies to be undertaken.

---------------------------------------------------------
Title: X-ray and Microwave Signatures of Coronal Mass Ejections
Authors: Gopalswamy, N.
1999spro.proc..141G    Altcode:
  X-ray and microwave imaging of structures associated with coronal mass
  ejections (CMEs) have provided a wealth of new information towards a
  better understanding of solar eruptions. I review the recent research
  based on microwave imaging from the Nobeyama Radioheliograph and X-ray
  imaging from the Yohkoh Soft X-ray Telescope. I shall discuss the
  advances made towards understanding the near surface manifestations
  of CMEs best observed in X-rays and microwaves. In particular,
  I discuss (i) observability of CMEs in X-rays and microwaves,
  (ii) coronal dimming, (iii) relation between CME substructures,
  (iv) heating and expansion of eruptive prominences, (v) timing of
  flare, CME and prominence eruptions, and (vi) CME mass estimates from
  non-optical observations.

---------------------------------------------------------
Title: Microwave Enhancement in Coronal Holes: Structure, Variability
    and Magnetic Nature
Authors: Gopalswamy, N.; Shibasaki, K.
1999STIN...0011601G    Altcode:
  The microwave enhancement in coronal holes in comparison with the
  quiet Sun is a distinct and easily observed signature related to the
  magnetic activity. This has proven to be a new tool to study the
  solar atmospheric layer where the fast solar wind originates. We
  have developed a catalog of a large number of coronal holes using
  images obtained by SOHO's Extreme-ultraviolet Imaging Telescope in
  EUV and by the Nobeyama radioheliograph in microwaves. We also have
  high resolution longitudinal magnetograms obtained by SOHO's Michelson
  Doppler Imager. We present the statistical properties of the microwave
  enhancements and discuss the small-scale dynamics as revealed by the
  magnetograms and radioheliograms. We also discuss the geoeffectiveness
  of these coronal holes.

---------------------------------------------------------
Title: "Driverless" Shocks in the Interplanetary Medium
Authors: Gopalswamy, N.; Kaiser, M. L.; Lara, A.
1999STIN...0011206G    Altcode:
  Many interplanetary shocks have been detected without an obvious driver
  behind them. These shocks have been thought to be either blast waves
  from solar flares or shocks due to sudden increase in solar wind speed
  caused by interactions between large scale open and closed field lines
  of the Sun. We investigated this problem using a set of interplanetary
  shock detected in situ by the Wind space craft and tracing their solar
  origins using low frequency radio data obtained by the Wind/WAVES
  experiment. For each of these "driverless shocks" we could find
  a unique coronal mass ejections (CME) event observed by the SOHO
  (Solar and Heliospheric Observatory) coronagraphs. We also found that
  these CMEs were ejected at large angles from the Sun-Earth line. It
  appears that the "driverless shocks" are actually driver shocks, but
  the drivers were not intercepted by the spacecraft. We conclude that
  the interplanetary shocks are much more extended than the driving CMEs.

---------------------------------------------------------
Title: X-ray and radio manifestations of a solar eruptive event
Authors: Gopalswamy, N.; Nitta, N.; Manoharan, P. K.; Raoult, A.;
   Pick, M.
1999A&A...347..684G    Altcode:
  We report on a study of the changes in the vicinity of a disappearing
  solar filament (DSF) that occurred on 1993 April 30. The DSF was
  associated with a long duration X-ray event (LDE) observed by the
  GOES and Yohkoh spacecraft. A detailed analysis of the X-ray images
  obtained by the Yohkoh Soft X-ray Telescope revealed that X-ray
  manifestations of the eruption were wide-spread: (i) X-ray enhancement
  over a coronal volume several times larger than that of the eruption
  region, probably the X-ray counterpart of a coronal mass ejection (CME),
  (ii) X-ray ejecta accelerating to 670 km s(-1) into the corona, and
  (iii) quasi-stationary X-ray loops as in long decay events (LDEs) were
  observed. One of the important findings of this study is the large-scale
  X-ray enhancement which we identify with the frontal structure of a
  CME, apart from the well-known X-ray ejecta and post-eruption arcade
  formation. There is evidence for triggering of a sympathetic flare in
  an adjoining active region due to the X-ray ejecta from the eruption
  region. Stationary metric radio continuum observed by the Nançay
  Radioheliograph was found to be associated with the brightest X-ray
  loops that formed following the filament eruption. The unpolarized
  continuum radio emission was found to be bremsstrahlung radiation
  from the hot plasma observed in X-rays. The event was also associated
  with a low frequency metric type II radio burst due to a coronal shock
  wave from the eruption region. The onset time of the type II emission
  precludes the possibility of a CME-driven shock causing it. Although
  we do not have positional information for the type II burst, we found
  that the X-ray ejecta was fast enough to drive the coronal shock. We
  confirmed this by comparing the speed of the X-ray ejecta with the
  shock speed obtained from the radio data which agreed within 10%.

---------------------------------------------------------
Title: Is the chromosphere hotter in coronal holes?
Authors: Gopalswamy, N.; Shibasaki, K.; Thompson, B. J.; Gurman,
   J. B.; Deforest, C. E.
1999AIPC..471..277G    Altcode: 1999sowi.conf..277G
  Coronal holes are brighter than the quiet Sun in microwaves. Microwave
  emission from the quiet Sun is optically thick thermal bremsstrahlung
  from the upper chromosphere. Therefore, the optically thick layer in the
  coronal hole chromosphere must be hotter than the corresponding layer
  in the quiet chromosphere. We present microwave and SOHO observations
  in support of this idea. Because of the availability of simultaneous
  EUV and microwave images it is now possible to obtain more details
  of this enigmatic phenomenon. In this paper, we highlight the primary
  properties of the microwave enhancement in coronal holes and point out
  some related phenomena. Finally, we summarize the possible explanations
  of the radio enhancement.

---------------------------------------------------------
Title: Dynamical phenomena associated with a coronal mass ejection
Authors: Gopalswamy, N.; Kaiser, M. L.; MacDowall, R. J.; Reiner,
   M. J.; Thompson, B. J.; Cyr, O. C. St.
1999AIPC..471..641G    Altcode: 1999sowi.conf..641G
  The flare-CME-shock relationship has been controversial for more than
  two decades. This issue was traditionally addressed using white light
  coronagraphic data on CMEs, H-alpha or GOES data on flares and radio
  spectrographic data on shocks (inferred from metric type II radio
  bursts). A wealth of new information has become available after the
  advent of Yohkoh, SOHO and WIND missions that can be used to address
  the dynamical phenomena associated with CMEs. We present multiwavelength
  observations of the 1998 April 27 CME associated with coronal dimming,
  an X-class flare and type II radio bursts. We find that the coronal
  dimming observed in X-rays and EUV is indeed a CME signature and that
  the CME clearly precedes the accompanying flare.

---------------------------------------------------------
Title: The Long Wavelength Array: Imaging Solar Bursts and CMEs
Authors: Gopalswamy, N.; Lazio, T. J. W.; Kassim, N. E.; Erickson,
   W. C.
1999AAS...19410308G    Altcode: 1999BAAS...31.1002G
  Almost all of the transient disturbances in the Sun-Earth connected
  space are amenable to probing by metric and decametric radio wavelengths
  (150 MHz down to ionospheric cut-off at 15 MHz). The long wavelength
  radio imaging with polarization capability is virtually the only way of
  measuring magnetic fields in the outer corona and hence an important
  tool in the study of long-term evolution of the Sun as it sheds its
  magnetic field through coronal mass ejections (CMEs). Shocks generated
  during the CMEs are detected as type II radio bursts; some of the
  energetic electrons are detected as type III bursts; ejected plasmoids
  are observed as type IV bursts. Ionospheric effects used to pose a
  major problem for long wavelength imaging. We now know that most of the
  shortcomings due to ionospheric effects can be virtually eliminated,
  thanks to the development in image restoration such as self-calibration
  (Kassim and Erickson, 1998). Low frequency technologies are relatively
  cheap and well proven. A synergistic combination of a ground based
  Long Wavelength Array (LWA) and the space-borne coronagraphs such as on
  board the STEREO mission could prove to be an extremely powerful tool to
  understand the interplanetary propagation of solar disturbances. Passive
  imaging of solar emissions can also be combined with radar imaging
  to increase the scientific return of the LWA (see poster by Lazio
  et al). The low frequency regime has also the advantage of combining
  solar physics with non-solar radio astronomy: Sun in the day time and
  the rest of the universe at night (see poster by Kassim et al). NG is
  an NAS/NRC Senior Research Associate at NASA/GSFC on leave from the
  Catholic University. Basic research in radio astronomy at the Naval
  Research Laboratory is supported by the Office of Naval Research.

---------------------------------------------------------
Title: Microwave enhancement and variability in the elephant's trunk
coronal hole: Comparison with SOHO observations
Authors: Gopalswamy, N.; Shibasaki, K.; Thompson, B. J.; Gurman, J.;
   DeForest, C.
1999JGR...104.9767G    Altcode:
  We report on an investigation of the microwave enhancement and its
  variability in the elephant's trunk coronal hole observed during the
  Whole Sun Month campaign (August 10 to September 9, 1996). The microwave
  images from the Nobeyama radioheliograph were compared with magnetograms
  and EUV images obtained simultaneously by the Michelson Doppler imager
  and the extreme ultraviolet imaging telescope (EIT) on board the SOHO
  spacecraft. The combined data set allowed us to understand the detailed
  structure of the microwave enhancement in the spatial and temporal
  domains. We find that the radio enhancement is closely associated
  with the enhanced unipolar magnetic regions underlying the coronal
  hole. The radio enhancement consists of a smooth component originating
  from network cell interiors and a compact component associated with
  network magnetic elements. When a minority polarity is present near
  a majority polarity element, within the coronal hole, the resulting
  mixed polarity region is associated with a bright-point-like emission
  in coronal EUV lines such as the Fe XII 195 Å. These coronal bright
  points are also observed distinctly in the EIT 304 Å band, but not
  in microwaves. On the other hand, the lower-temperature line emission
  (304 Å) and the microwave enhancement are associated with the unipolar
  magnetic flux elements in the network. We found strong time variability
  of the radio enhancement over multiple timescales, consistent with the
  initial results obtained by SOHO instruments. The microwave enhancement
  is most probably due to temperature enhancement in the chromosphere
  and may be related to the origin of solar wind.

---------------------------------------------------------
Title: Synoptic Sun during the first Whole Sun Month Campaign:
    August 10 to September 8, 1996
Authors: Biesecker, D. A.; Thompson, B. J.; Gibson, S. E.; Alexander,
   D.; Fludra, A.; Gopalswamy, N.; Hoeksema, J. T.; Lecinski, A.;
   Strachan, L.
1999JGR...104.9679B    Altcode:
  A large number of synoptic maps from a variety of instruments are used
  to show the general morphology of the Sun at the time of the First
  Whole Sun Month Campaign. The campaign was conducted from August 10 to
  September 8, 1996. The synoptic maps cover the period from Carrington
  rotation 1912/253° to Carrington rotation 1913/45°. The synoptic maps
  encompass both on-disk data and limb data from several heights in the
  solar atmosphere. The maps are used to illustrate which wavelengths and
  data sets show particular features, such as active regions and coronal
  holes. Of particular interest is the equatorial coronal hole known as
  the “elephant's trunk,” which is clearly evident in the synoptic
  maps of on-disk data. The elephant's trunk is similar in appearance
  to the Skylab-era, “Boot of Italy,” equatorial coronal hole. The
  general appearance of the limb maps is explained as well. The limb
  maps also show evidence for equatorial coronal holes.

---------------------------------------------------------
Title: Radio Imaging of the Sun from Space
Authors: Rodriguez, P.; Kassim, N. E.; Weiler, K. W.; Kaiser, M. L.;
   Reiner, M. J.; MacDowall, R. A.; Jones, D. L.; Unwin, S. C.; Kuiper,
   T. B.; Gopalswamy, N.
1999AAS...194.7604R    Altcode: 1999BAAS...31R.956R
  Since the 1960s, ground-based radio astronomers have had the
  capability to image solar radio emissions using aperture synthesis
  techniques. These images show the two-dimensional time history of
  CME-driven shock fronts, for example. However, ground-based observations
  are limited by the terrestrial ionosphere to frequencies above about 15
  MHz, which corresponds to a maximum solar altitude of about one solar
  radius. To probe the altitude range from one solar radius to one AU
  requires space-based radio telescopes. Many space-based low-frequency
  radio telescopes have flown over the past three decades, but they
  all suffered from lack of angular resolution because they consisted
  of single spacecraft carrying simple dipole antennas. Even with this
  limitation, much progress has been made by utilizing spacecraft spin to
  deduce source location and size, thereby permitting tracking of solar
  radio sources between the sun and Earth. However, no structural detail
  is available from this technique, only source centroids and approximate
  angular size. To provide a greater level of structural detail,
  we need to take the next logical step in low-frequency solar radio
  astronomy: aperture synthesis from space. We believe this can be done
  with currently-available hardware as a medium-class Explorer (MIDEX)
  mission. This mission would consist of approximately 16 identical
  and quite simple micro-spacecraft in a spherical array approximately
  100 km in diameter. The array should be situated relatively far from
  Earth (to lessen terrestrial interference), such as at the distant
  retrograde class of orbits at about one million kilometers from
  Earth. This array will be capable of imaging not only solar transient
  events to unprecedented altitudes, but also the quiet sun, the entire
  terrestrial magnetosphere via scattering in the magnetosheath, and the
  low-frequency cosmic background, the latter being a totally unexplored
  radio window. This work is supported in part by ONR and NASA.

---------------------------------------------------------
Title: The Long Wavelength Array: A Ground-Based Coronal Mass
    Ejection Detector
Authors: Lazio, T. J. W.; Kassim, N. E.; Rodriguez, P.; Gopalswamy,
   N.; Erickson, W. C.
1999AAS...194.7605L    Altcode: 1999BAAS...31..956L
  We describe the Long Wavelength Array (LWA), a ground-based radio
  interferometer capable of serving as a coronal mass ejection (CME)
  detector. Previous low-frequency (nu &lt; 50 MHz) coronal sounding
  experiments have shown that CMEs exhibit large radar cross sections. The
  LWA will serve as the imaging receiver for a bi-static radar observatory
  that will open an entirely new field of CME research. Because the LWA
  will be a synthesis interferometer, it will be capable of imaging the
  return echo as well as measuring its Doppler shift. The combination
  of Doppler shift, to provide the radial velocity, and the imaging,
  to provide the transverse velocity, means that the LWA will determine
  the total space velocity of the CME, crucial for inferring arrival
  times of Earthward-bound events for geomagnetic storm predictions. A
  ground-based system operating with low cost HF/VHF technology, the LWA
  will be considerably less expensive and more reliable than planned
  stereoscopic space-based CME detection schemes. In addition to the
  practical importance to spacecraft, communication, and electrical power
  systems, the reliable detection and monitoring of CMEs will allow the
  study of the angular distribution, ranges, and line-of-sight velocities
  of CMEs. Additional papers at this meeting describe possibilities of the
  LWA for astrophysical applications (Kassim et al.) and passive solar
  observations (Gopalswamy et al.). Basic research in radio astronomy
  at the Naval Research Laboratory is supported by the Office of Naval
  Research.

---------------------------------------------------------
Title: Reply
Authors: Gopalswamy, N.; Kaiser, M. L.; Lepping, R. P.; Berdichevsky,
   D.; Ogilvie, K.; Kahler, S. W.; Kondo, T.; Isobe, T.; Akioka, M.
1999JGR...104.4749G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Catholic University of America Institute for Astrophysics
    and Computational Sciences, Department of Physics, Washington,
    District of Columbia 20064. Report for the period Sep 1997 - Sep 1998.
Authors: Gopalswamy, N.
1999BAAS...31...13G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Study of the dynamics of the solar RA(7794) during october
    29 1994 with VLA at 2 and 20 cm.
Authors: Torres Papaqui, J. P.; Gopalswamy, N.; Mendoza-Torres, J. E.
1998larm.confE..16T    Altcode:
  We report VLA observation made at 2 and 20 cm of a solar active region
  (AR) where flares, were observed in October 29, 1994. The aim of the
  work is to study the variations in intensity and polarization, during
  this day, of different zones in the AR. The zones under study are:
  1) Those where the flares took place, 2) the zones of the AR where
  the maximum intensities, during the day, were observed and 3) the
  zones of higher polarization. The zones where the flares occurred were
  selected to follow the time variati ons before and after the flares. The
  other zones were selected to look for possible variables that could
  be related to the flares. An IDL programm that allows systematically
  analyse temporal variations of different zones was made. The program
  was applied to images made for time intervals of 10 sec. The whole
  interval of observations was of about 6 hours. The results of this
  analysis are presented in this work.

---------------------------------------------------------
Title: On the relationship between coronal mass ejections and
    magnetic clouds
Authors: Gopalswamy, N.; Hanaoka, Y.; Kosugi, T.; Lepping, R. P.;
   Steinberg, J. T.; Plunkett, S.; Howard, R. A.; Thompson, B. J.;
   Gurman, J.; Ho, G.; Nitta, N.; Hudson, H. S.
1998GeoRL..25.2485G    Altcode:
  We compare the substructures of the 1997 February 07 coronal mass
  ejection (CME) observed near the Sun with a corresponding event in
  the interplanetary medium to determine the origin of magnetic clouds
  (MCs). We find that the eruptive prominence core of the CME observed
  near the Sun may not directly become a magnetic cloud as suggested by
  some authors and that it might instead become the ”pressure pulse”
  following the magnetic cloud. We substantiate our conclusions using time
  of arrival, size and composition estimates of the CME-MC substructures
  obtained from ground based, SOHO and WIND observations.

---------------------------------------------------------
Title: Type II radio emissions in the frequency range from 1-14 MHz
    associated with the April 7, 1997 solar event
Authors: Kaiser, M. L.; Reiner, M. J.; Gopalswamy, N.; Howard, R. A.;
   St. Cyr, O. C.; Thompson, B. J.; Bougeret, J. -L.
1998GeoRL..25.2501K    Altcode:
  We present an analysis of radio emissions associated with the April
  7, 1997 solar eruptive event. The event consisted of a filament
  disappearance, a complex two-phase coronal mass ejection (CME),
  and a C6.9, 2N flare. At the same time, intermittent type II radio
  emissions in the frequency range 1-10 MHz, corresponding to an altitude
  range of 2-15 R<SUB>o</SUB>, were observed by the Wind/WAVES radio
  receiver. Using the onset times and inferred heights and speeds
  of the radio bursts, we considered both a CME-driven shock and a
  flare-associated blast wave shock as possible causes of the type II
  radio emissions. We conclude that some of the radio emissions in the
  WAVES data are associated with each shock. The type II radio emissions
  associated with the blast wave shock were farther from the sun than
  any emission of this type that has been reported previously.

---------------------------------------------------------
Title: The solar origin of the January 1997 coronal mass ejection,
    magnetic cloud and geomagnetic storm
Authors: Webb, D. F.; Cliver, E. W.; Gopalswamy, N.; Hudson, H. S.;
   St. Cyr, O. C.
1998GeoRL..25.2469W    Altcode:
  The magnetic cloud and geomagnetic storm on January 10-11, 1997 were
  associated with a halo-type Coronal Mass Ejection (CME) observed by
  the SOHO/LASCO coronagraphs near the sun on January 6. We summarize
  the solar activity related to this CME and the subsequent storm at
  Earth. This solar activity was remarkably weak and unimpressive. If
  the wide CME had not been observed, the storm would not have been
  forecast. Thus this case represents an extreme example of so-called
  “problem” magnetic storms that lack obvious surface signatures of
  eruptive solar activity. It supports the view that CMEs involve the
  destabilization of large-scale coronal structures which may or may
  not have associated surface activity, and that CMEs, not the surface
  activity, are the key causal link between solar eruptions and space
  weather at Earth.

---------------------------------------------------------
Title: Spatial Structure of Solar Coronal Magnetic Loops Revealed
    by Transient Microwave Brightenings
Authors: Zhang, J.; Gopalswamy, N.; Kundu, M. R.; Schmahl, E. J.;
   Lemen, J. R.
1998SoPh..180..285Z    Altcode:
  We present the measurement of magnetic field gradient in magnetic
  loops in the solar corona, based on the multi-wavelength Very Large
  Array observations of two transient microwave brightenings (TMBs)
  in the solar active region 7135. The events were observed at 2 cm
  (spatial resolution ∼ 2=) and 3.6 cm (spatial resolution ∼ 3=)
  with a temporal resolution of 3.3 s in a time-sharing mode. Soft X-ray
  data (spatial resolution ∼ 2.5=) were available from the Soft X-ray
  Telescope on board the Yohkoh satellite. The three-dimensional structure
  of simple magnetic loops, where the transient brightenings occurred,
  were traced out by these observations. The 2-cm and 3.6-cm sources
  were very compact, located near the footpoint of the magnetic loops
  seen in the X-ray images. For the two events reported in this paper,
  the projected angular separation between the centroids of 2 and 3.6-cm
  sources is about 2.3= and 3.1=, respectively. We interpret that the 2
  and 3.6-cm sources come from thermal gyro-resonance emission. The 2-cm
  emission is at the 3rd harmonic originating from the gyro-resonance
  layer where the magnetic field is 1800 G. The 3.6-cm emission is at
  the 2nd harmonic, originating from the gyro-resonance layer with a
  magnetic field of 1500 G. The estimated magnetic field gradient near
  the footpoint of the magnetic loop is about 0.09 G km=<SUP>1</SUP> and
  0.12 G km=<SUP>1</SUP> for the two events. These values are smaller
  than those observed in the photosphere and chromosphere by at least
  a factor of 2.

---------------------------------------------------------
Title: Coronal Dimming Associated with a Giant Prominence Eruption
Authors: Gopalswamy, N.; Hanaoka, Y.
1998ApJ...498L.179G    Altcode:
  We report the results of our investigation of a giant eruptive
  prominence (initial mass ~6×10<SUP>16</SUP> g) using microwave,
  X-ray, and white-light observations. The prominence erupted from
  the northwest limb of the Sun on 1994 April 5. The speed of the
  prominence was only ~70 km s<SUP>-1</SUP> when it reached a height
  of ~0.5 R<SUB>solar</SUB> above the solar surface. In X-rays, a large
  region with reduced X-ray emission was observed enveloping the initial
  location of the prominence and extending to much larger heights. At
  the bottom of this depletion and beneath the eruptive prominence,
  an X-ray arcade formed, progressively spreading from south to north
  along the limb. This is the first time a direct detailed comparison is
  made between coronal dimming and a prominence eruption. We were able to
  confirm that the coronal dimming is indeed a near-surface manifestation
  of the coronal mass ejection (CME). The orientation of the structures
  involved did not allow the observations of the coronal cavity, but
  all the other substructures of the CME could be identified. The mass
  expelled from the Sun in the form of the eruptive prominence and the
  coronal dimming are comparable. The estimated total mass is somewhat
  larger than that reported in other X-ray-dimming events.

---------------------------------------------------------
Title: Microwave and Soft X-ray Study of Solar Active Region Evolution
Authors: Lara, A.; Gopalswamy, N.; Kundu, M. R.; Pérez-Enríquez,
   R.; Koshiishi, H.; Enome, S.
1998SoPh..178..353L    Altcode:
  We have studied the properties and evolution of several active
  regions observed at multiple wavelengths over a period of about 10
  days. We have used simultaneous microwave (1.5 and 17 GHz) and soft
  X-ray measurements made with the Very Large Array (VLA), the Nobeyama
  Radio Heliograph (NRH) and the Soft X-ray Telescope (SXT) on board
  the Yohkoh spacecraft, as well as photospheric magnetograms from
  KPNO. This is the first detailed comparison between observations at
  radio wavelengths differing by one order of magnitude. We have performed
  morphological and quantitative studies of active region properties by
  making inter-comparison between observations at different wavelengths
  and tracking the day-to-day variations. We have found good general
  agreement between the 1.5 and 17 GHz radio maps and the soft X-rays
  images. The 17 GHz emission is consistent with thermal bremsstrahlung
  (free-free) emission from electrons at coronal temperatures plus a small
  component coming from plasma at lower temperatures. We did not find
  any systematic limb darkening of the microwave emission from active
  regions. We discuss the difference between the observed microwave
  brightness temperature and the one expected from X-ray data and in
  terms of emission of a low temperature plasma at the transition region
  level. We found a coronal optical thickness of ∼ 10<SUP>-3</SUP>
  and ∼ 1 for radiation at 17 and 1.5 GHz, respectively. We have
  also estimated the typical coronal values of emission measure (∼
  5 × 10<SUP>28</SUP> cm<SUP>-5</SUP>), electron temperature (∼
  4.5 × 10<SUP>6</SUP>6 K) and density (∼ 1.2 × 10<SUP>9</SUP>
  cm<SUB>3</SUB>). Assuming that the emission mechanism at 17 GHz is
  due to thermal free-free emission, we calculated the magnetic field
  in the source region using the observed degree of polarization. From
  the degree of polarization, we infer that the 17 GHz radiation is
  confined to the low-lying inner loop system of the active region. We
  also extrapolated the photospheric magnetic field distribution to the
  coronal level and found it to be in good agreement with the coronal
  magnetic field distribution obtained from microwave observations.

---------------------------------------------------------
Title: Multiwavelength Observations of a Coronal Hole
Authors: Gopalswamy, N.; Shibasaki, K.; Deforest, C. E.; Bromage,
   B. J. I.; Del Zanna, G.
1998ASPC..140..363G    Altcode: 1998ssp..conf..363G
  No abstract at ADS

---------------------------------------------------------
Title: Comparison of Microwave and SOHO Synoptic Maps of the Sun
    During the Whole Sun Month, 1996
Authors: Gopalswamy, N.; Thompson, B. J.; Shibasaki, K.
1998ASPC..140..401G    Altcode: 1998ssp..conf..401G
  No abstract at ADS

---------------------------------------------------------
Title: The Catholic University of America, Institute for Astrophysics
    and Computational Sciences, Department of Physics, Washington,
    DC 20064. Report for the period Sep 1996 - Sep 1997.
Authors: Gopalswamy, N.
1998BAAS...30...32G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Radio and X-ray Investigations of Erupting Prominences (Review)
Authors: Gopalswamy, N.; Hanoka, Y.; Lemen, J. R.
1998ASPC..150..358G    Altcode: 1998IAUCo.167..358G; 1998npsp.conf..358G
  No abstract at ADS

---------------------------------------------------------
Title: Birth Place of the 1998 January 21 CME
Authors: Gopalswamy, N.; Hanaoka, Y.; Kaiser, M.; Gurman, J.; Hudson,
   H.; Howard, R. A.
1998cee..workE..40G    Altcode:
  The 1998 January 21 halo coronal mass ejection was launched
  from high southern latitudes in association with a filament
  disappearance observed by the Nobeyama Radioheliograph. Signatures
  of the initial destabilization of the filament were observed by
  the Extreme-ultraviolaet Imaging Telescope (EIT) on board the SOHO
  spacecraft and by the Soft X-ray Telescope (SXT) on board Yohkoh. The
  Wind/WAVES experiment observed a type II burst in the 600-300 kHz
  range. The data coverage for this event is unusually high and we make
  use of it to understand the origin and evolution of the eruption. We
  address several issues based on these data: (i) relation between
  filament eruption and arcade formation beneath the filament, (ii)
  comparison between the hot arcade formation in X-rays and EUV, (iii)
  relation between the filament eruption and the white light CME, (iv)
  relation between the CME and the interplanetary shock inferred from the
  WAVES data. A summary of near-surface activities associated with the
  eruption can be seen in the Figure 1. Figure 1. SOHO/MDI longitudinal
  magnetogram, with radio filament (white contours) and X-ray emission
  (enclosed by dark lines) are overlaid. The thick white line from E to
  W is the neutral line over which the eruption took place. North is to
  the top and east is to the left. F is the location where the filament
  split at the time of eruption.

---------------------------------------------------------
Title: Microwave Imaging in Support of the SERTS'97 Flight
Authors: Gopalswamy, N.; Hanaoka, Y.
1998AAS...191.7317G    Altcode: 1998BAAS...30..758G
  The Solar Extreme-ultraviolet Rocket Telescope and Spectrograph flown
  successfully on 1997 November 18 at 19:35 UT and an observing campaign
  was conducted to support the flight. Coordinated observations were
  obtained by SOHO and YOHKOH and many ground based instruments. Radio
  observations were obtained by the Very Large Array (VLA) and the
  Nobeyama Radioheliograph in microwaves. The SERTS target was the
  trailing portion of a large active region (NOAA AR 8108) close to
  the disk center (N19E17 at 19:40 UT on 1997 November 18). The VLA
  obtained microwave images at 20, 6 and 3.6 cm wavelengths with a
  spatial resolution of about 40", 12" and 7" respectively. The Nobeyama
  images (spatial resolution 10") were obtained a few hours later at 1.7
  cm. The microwave images (in total intensity and circular polarization)
  provide information on the physical conditions (temperature, density and
  magnetic field) in the active region corona and in sunspots at various
  heights above the solar surface. The AR was relatively quiet during the
  SERTS flight, so we can determine its quiescent properties. We present
  preliminary radio images of AR 8108 and the physical conditions derived
  from them. We thank T. Bastian for help in obtaining VLA observing
  time. This research was supported by NASA grant NAG-5-6139.

---------------------------------------------------------
Title: Origin of coronal and interplanetary shocks: A new look with
    WIND spacecraft data
Authors: Gopalswamy, N.; Kaiser, M. L.; Lepping, R. P.; Kahler, S. W.;
   Ogilvie, K.; Berdichevsky, D.; Kondo, T.; Isobe, T.; Akioka, M.
1998JGR...103..307G    Altcode:
  We have investigated type II radio bursts in the solar corona using
  data from ground-based radio telescopes (&gt;18MHz) and from the
  Radio and Plasma Wave experiment (WAVES) on board the WIND spacecraft
  (&lt;14MHz). The wavelength range of the WAVES experiment includes the
  2- to 14-MHz band, previously unobserved from space. We found that all
  34 coronal type II bursts observed over a period of 18 months (November
  1, 1994, to April 30, 1996), decayed within a few solar radii and did
  not propagate into the interplanetary medium. On the other hand, most
  of the accompanying type III radio bursts observed by the ground-based
  instruments were observed to continue into the interplanetary medium
  as the electron beams propagated freely along open magnetic field
  lines. Over the same period of time, other instruments on board the
  WIND spacecraft detected about 18 interplanetary shock candidates,
  which seem to be unrelated to the coronal type II bursts. This result
  confirms the idea that the coronal and interplanetary shocks are two
  different populations and are of independent origin. We reexamine the
  data and conclusions of Gosling et al. [1976], Munro et al. [1979],
  and Sheeley et al. [1984] and find that their data are consistent
  with our result that the coronal type II bursts are due to flares. We
  also briefly discuss the implications of our result to the modeling
  studies of interplanetary shocks based on input from coronal type II
  radio bursts.

---------------------------------------------------------
Title: Fast Time Structure during Transient Microwave Brightenings:
    Evidence for Nonthermal Processes
Authors: Gopalswamy, N.; Zhang, J.; Kundu, M. R.; Schmahl, E. J.;
   Lemen, J. R.
1997ApJ...491L.115G    Altcode: 1997astro.ph.10200G
  Transient microwave brightenings (TMBs) are small-scale energy releases
  from the periphery of sunspot umbrae with a flux density 2 orders
  of magnitude smaller than that from a typical flare. Gopalswamy et
  al. first reported the detection of the TMBs, and it was pointed out
  that the radio emission implied a region of very high magnetic field
  so that the emission mechanism has to be gyroresonance or nonthermal
  gyrosynchrotron, but not free-free emission. It was not possible to
  decide between gyroresonance and gyrosynchrotron processes because
  of the low time resolution (30 s) used in the data analysis. We have
  since performed a detailed analysis of the Very Large Array data with
  full time resolution (3.3 s) at two wavelengths (2 and 3.6 cm), and we
  can now adequately address the question of the emission mechanism of
  the TMBs. We find that nonthermal processes indeed take place during
  the TMBs. We present evidence for nonthermal emission in the form of
  temporal and spatial structure of the TMBs. The fast time structure
  cannot be explained by a thermodynamic cooling time and therefore
  requires a nonthermal process. Using the physical parameters obtained
  from X-ray and radio observations, we determine the magnetic field
  parameters of the loop and estimate the energy released during the
  TMBs. The impulsive components of TMBs imply an energy release rate
  of ~1.3×10<SUP>22</SUP> ergs s<SUP>-1</SUP>, so the thermal energy
  content of the TMBs could be less than ~10<SUP>24</SUP> ergs.

---------------------------------------------------------
Title: X-Ray and Radio Studies of a Coronal Eruption: Shock Wave,
    Plasmoid, and Coronal Mass Ejection
Authors: Gopalswamy, N.; Kundu, M. R.; Manoharan, P. K.; Raoult, A.;
   Nitta, N.; Zarka, P.
1997ApJ...486.1036G    Altcode:
  On 1994 July 31, a fast (900 km s<SUP>-1</SUP>) eruptive structure
  was observed in X-rays, followed by a slower plasmoid (180 km
  s<SUP>-1</SUP>). They were associated with a coronal mass ejection,
  prominence eruption, and a host of metric radio bursts. The X-ray
  structure seems to be a part of a white light coronal mass ejections
  (CME), as inferred from the white light images of July 30 and 31. A type
  II burst was observed at the leading edge of the X-ray eruption, while a
  type IV burst was spatially associated with the detached plasmoid. The
  type III radio bursts occurred on thin overdense structures associated
  with the eruption. We detected the rise of plasma levels because
  of mass addition to the type III burst sources as a result of the
  eruption. This event further clarifies the manifestation of a CME in
  X-rays. We identify the X-ray eruption as the driver of the coronal
  shock wave. This provides answer to the long-standing question regarding
  the origin of coronal and interplanetary shock waves. We have also found
  evidence to support the idea that herringbone bursts are produced when
  the coronal shock wave crosses open magnetic field lines.

---------------------------------------------------------
Title: Signatures of Coronal Currents in Microwave Images
Authors: Lee, Jeongwoo; White, Stephen M.; Gopalswamy, N.; Kundu, M. R.
1997SoPh..174..175L    Altcode:
  Microwave emission from solar active regions at frequencies above 4
  GHz is dominated by gyroresonance opacity in strong coronal magnetic
  fields, which allows us to use radio observations to measure coronal
  magnetic field strengths. In this paper we demonstrate one powerful
  consequence of this fact: the ability to identify coronal currents
  from their signatures in microwave images. Specifically, we compare
  potential-field (i.e., current-free) extrapolations of photospheric
  magnetic fields with microwave images and are able to identify regions
  where the potential extrapolation fails to predict the magnetic field
  strength required to explain the microwave images. Comparison with
  photospheric vector magnetic field observations indicates that the
  location inferred for coronal currents agrees with that implied by the
  presence of vertical currents in the photosphere. The location, over
  a neutral line exhibiting strong shear, is also apparently associated
  with strong heating.

---------------------------------------------------------
Title: Tracking a CME from Cradle to Grave: A Multi-wavelength
    Analysis of the February 6-7, 1997 Event
Authors: Gopalswamy, N.; Kundu, M. R.; Hanaoka, Y.; Kosugi, T.; Hudson,
   H.; Nitta, N.; Thompson, B.; Gurman, J.; Plunkett, S.; Howard, R.;
   Burkepile, J.
1997SPD....28.0501G    Altcode: 1997BAAS...29..908G
  The partially earth-directed coronal mass ejection (CME) event of 1997
  February 6-7 originated from the southwest quadrant of the sun. The
  CME accelerated from 170 km/s to about 830 km/s when it reached a
  distance of 25 solar radii. The CME was an arcade eruption followed
  by bright prominence core structures. The prominence core was tracked
  continuously from the solar surface to the interplanetary medium by
  combining data from the Nobeyama radioheliograph (microwaves), Mauna Loa
  Solar Observatory (He 10830 { Angstroms}), SOHO/EIT (EUV) and SOHO/LASCO
  (white light). The CME was accompanied by an arcade formation, fully
  observed by the YOHKOH/SXT (soft X-rays) and SOHO/EIT (EUV). The X-ray
  and EUV observations suggest that the reconnection proceeded from
  the northwest end to the southeast end of a filament channel. In the
  SOHO/EIT images, the the feet of the soft X-ray arcade were observed
  as EUV ribbons. The CME event also caused a medium sized geomagnetic
  storm: The hourly equatorial Dst values attained storm level during
  18:00-19:00 UT on February 09. This means the disturbance took about
  2.25 days to reach the Earth. The first signatures of an IP shock was
  a pressure jump in the WIND data around 13:00 UT on Feb 09, 1997 which
  lasted for about 14 hours, followed by flux rope signatures. This CME
  event confirms a number of ideas about CMEs: The three part structure
  (frontal bright arcade, dark cavity and prominence core), disappearing
  filament, elongated arcade formation, and terrestrial effects. We make
  use of the excellent data coverage from the solar surface to the Earth
  to address a number of issues regarding the origin and propagation of
  the geoeffective solar disturbances. We benefited from discussions at
  the first SOHO-Yohkoh Coordinated Data Analysis Workshop, held March
  3-7, 1997, at Goddard Space Flight Center.

---------------------------------------------------------
Title: The Solar Source of the January 1997 CME/Magnetic Cloud;
    Recurrent Activity on a Polar Crown Filament Channel
Authors: Webb, David; Cliver, E.; McIntosh, P.; Gopalswamy, N.;
   Hudson, H.
1997SPD....28.1501W    Altcode: 1997BAAS...29..918W
  The magnetic cloud and geomagnetic storm on 10-11 January 1997 was
  associated with a halo-type CME observed by LASCO near the sun on 6
  January. As part of the ISTP and SHINE collaboration on this event we
  are studying the solar source region of the CME and its propagation
  through the interplanetary medium to Earth. We summarize the rather
  weak solar activity that apparently was associated with this CME, and
  contrast it with the strong surface and coronal activity associated
  with the 9-11 February 1997 magnetic cloud/storm. We present evidence
  that the solar sources of both of these events occurred over an area
  where the southern polar crown filament channel diverted sharply to
  the north and in the decaying remnants of the first large-scale active
  region to form during the new solar cycle. Our results also suggest
  that this region was the site of earlier CMEs; i.e., it was a key site
  of recurrent activity during 1996-97 which, when aimed toward Earth,
  produced recurrent magnetic clouds and storms.

---------------------------------------------------------
Title: Multi-wavelength Observations of Transient Microwave
    Brightenings in a Solar Active Region
Authors: Zhang, Jie; Gopalswamy, N.; Kundu, M. R.; Schmahl, E. J.;
   Lemen, J. R.
1997SPD....28.0163Z    Altcode: 1997BAAS...29..891Z
  We present multi-wavelength Very Large Array observations of two
  transient microwave brightenings (TMBs) in the solar active region
  7135. The events were observed at 2 cm (spatial resolution ~ 2”) and
  3.6 cm (spatial resolution ~ 3”) with a temporal resolution of 3.3 s
  in a time-sharing mode. Soft X-ray data (about 5” spatial resolution)
  were available from the Soft X-ray Telescope on board the YOHKOH
  satellite. The 2 cm and 3.6 cm emission sources were very compact,
  located near the footpoint of the magnetic loops seen in the X-ray
  images. The TMBs traced out the three dimensional structure of the
  magnetic loops where the transient brightenings occurred. For the
  two events reported in this paper, the projected angular separation
  between the centroids of 2 and 3.6 cm source is about 2.3” and 3.1”,
  respectively. We interpret the spatial and temporal distributions
  as implying that the 2 and 3.6 cm flux is mainly due to thermal
  gyro-resonance emmision. The 2 cm emission seems to be at the 3rd
  gyro-harmonic coming from the 1800 G gyro-resonance layer. The 3.6 cm
  emission seems to be at both the 2nd and 3rd harmonics, originating
  from gyro-resonance layers with a magnetic field of 1500 G and 1000
  G, respectively. However, the two gyro-resonance layers for 3.6 cm
  emission are not resolved with the current spatial resolution. The
  estimated magnetic field gradient near the footpoint of the magnetic
  loop is about 0.17 G km(-1) and 0.22 G km(-1) for the two events.

---------------------------------------------------------
Title: Source Parameters for Impulsive Bursts Observed in the Range
    18-23 GHz
Authors: Sawant, H. S.; Rosa, R. R.; Cecatto, J. R.; Gopalswamy, N.
1997SoPh..171..155S    Altcode:
  Here, we report on impulsive solar radio bursts observed for the
  first time with high time/spectral resolution in the range 18
  to 23 GHz. Using observational parameters and assuming nonthermal
  gyrosynchrotron emission from energetic electrons in a loop structure,
  we have estimated the density of nonthermal electrons, magnetic field,
  and dimension of the source along the line of sight.

---------------------------------------------------------
Title: A Multi-Wavelength Analysis of the February 6/7, 1997 Coronal
    Mass Ejection
Authors: Plunkett, S. P.; Gopalswamy, N.; Kundu, M. R.; Howard, R. A.;
   Thompson, B. J.; Gurman, J. B.; Lepping, R. P.; Hudson, H. S.; Nitta,
   N.; Hansoka, Y.; Kosugi, T.; Burkepile, J. T.
1997ESASP.404..615P    Altcode: 1997cswn.conf..615P
  No abstract at ADS

---------------------------------------------------------
Title: Radio and X-Ray Studies of a Coronal Mass Ejection Associated
    with a Very Slow Prominence Eruption
Authors: Gopalswamy, N.; Hanaoka, Y.; Kundu, M. R.; Enome, S.; Lemen,
   J. R.; Akioka, M.; Lara, A.
1997ApJ...475..348G    Altcode:
  We report on the observations of an X-ray coronal mass ejection
  (CME) with its three part structure: frontal loop, coronal cavity,
  and the eruptive prominence core. The prominence core was observed in
  microwaves, and the frontal loop was observed in X-rays. A coronal
  volume much larger than that occupied by the prominence seems to be
  affected by the eruption. Formation of an arcade structure was also
  observed beneath the erupting prominence. X-ray enhancement at the
  arcade persisted for several hours similar to long decay events. At
  the apex of the arcade there was a bright knot, which we interpret
  as the reconnection region from which the filament gets detached. We
  determined the trajectories of the frontal loop and the prominence core
  and found them to have very different characteristics. The CME showed an
  extremely small acceleration, while the prominence had a linear motion
  in the beginning followed by an exponential rise. However, during the
  several hours of simultaneous observation, the prominence did not catch
  up with the frontal loop. We determined the evolution of the CME mass,
  which increased by a factor of 4 during our observations. We discuss
  the implications of the observations in the general context of coronal
  mass ejections.

---------------------------------------------------------
Title: A Giant Prominence Eruption Observed by Nobeyama
    Radioheliograph and YOHKOH Spacecraft
Authors: Gopalswamy, N.; Hanaoka, Y.; Kundu, M. R.; Shibasaki, K.;
   Koshiishi, H.; Enome, S.; Lemen, J. R.
1997IAUJD..19E...4G    Altcode:
  The results of an investigation of a giant prominence which erupted from
  the northwest limb of the Sun on 1994 April 05, will be reported. The
  event could be traced back to a large prominence of March 19, 1994
  above the east limb. The filament was located in the north-south
  direction when it appeared on the disk. At about 23:00 UT on April 05,
  the filament started slowly rising and then accelerated. The speed of
  the prominence was was only 75 km s^{-1} when it reached a height of
  about 0.5 R_ odot above the surface. Preliminary examination shows that
  the eruption caused a geomagnetic storm on April 07 at 20:00 UT. We
  study the dynamical and physical properties of the erupting prominence
  and obtain physical parameters of the prominence plasma. In X-rays, the
  region of eruption was relatively faint. After the eruption, however,
  there was a large void at the previous location of the prominence and
  an arcade formed progressively spreading from south to north along
  the limb. Based on the X-ray and radio observations, we determine the
  characteristics of the pre- and post-eruption structures.

---------------------------------------------------------
Title: Yohkoh/SXT observations of a coronal mass ejection near the
    solar surface
Authors: Gopalswamy, N.; Kundu, M. R.; Hanaoka, Y.; Enome, S.; Lemen,
   J. R.; Akioka, M.
1996NewA....1..207G    Altcode:
  We report the observations of a coronal mass ejection (CME) using
  the Soft X-ray Telescope on board the Yohkoh Mission. The CME had
  the familiar three part structure (frontal loop, prominence core
  and a cavity). The erupting prominence was observed by the Nobeyama
  radioheliograph. We were able to determine the mass of the CME (2.6
  × 10<SUP>14</SUP> g) from X-ray observations which seems to be at
  the lower end of the range of CME masses reported before from white
  light observations. This is the first time the mass of a CME has been
  determined from X-ray observations. The height of onset of the CME
  was 0.3R<SUB>⊙</SUB>. The CME moved much faster than the erupting
  prominence while its acceleration was smaller than that of the erupting
  prominence. J. Leonard Culhane

---------------------------------------------------------
Title: Radio and X-ray manifestations of a bright point flare
Authors: Gopalswamy, N.; Kundu, M. R.; Hanaoka, Y.; Enome, S.; Lemen,
   J. R.
1996AIPC..374..408G    Altcode: 1996hesp.conf..408G
  We have found remarkably different manifestations of a bright point
  flare in X-ray and radio (microwave) wavelengths, unlike previous
  observations. In X-rays, the BP flare was relatively simple while
  in radio, the bright point flare had a large scale component and
  a transient moving component. The large scale structure may be the
  radio counterpart of large scale structures sometimes seen during
  X-ray BP flares. The transient component was also compact and moved
  away from the location of the X-ray BP flare with a speed of ∼60
  km s<SUP>-1</SUP>. The compact source also showed fast time structure
  which suggests nonthermal emission mechanism for the transient sources.

---------------------------------------------------------
Title: Tracking Type III and Type II Solar Radio Bursts from Metric
    to Hectometric Wavelengths using Ground-based and Space-borne
    Observations
Authors: Gopalswamy, N.; Kundu, M. R.; Kaiser, M. L.; Kahler, S. W.;
   Kondo, T.; Isobe, T.; Akioka, M.
1996AAS...188.1908G    Altcode: 1996BAAS...28..851G
  There exists a controversy regarding the origin of coronal and
  interplanetary (IP) shocks. Present observations shows that coronal
  shocks are associated with flares while the IP shocks are associated
  with coronal mass ejections (CMEs). An important question in this
  connection is whether the IP shocks are extensions of the coronal
  shocks or they are independently driven by CMEs. The coronal shocks
  have traditionally been inferred from metric type II radio bursts. The
  ionospheric cut-off around 20 MHz had been a hurdle in arriving at
  a firm conclusion regarding the continuation of type II bursts to
  frequencies lower than the ionospheric cut off. The WAVES experiment on
  board the WIND spacecraft has essentially removed this hurdle so that
  we are able to track metric radio bursts to hectometric wavelengths. We
  have identified about two dozen type II bursts observed by the Hiraiso
  Radio Spectrograph (HiRAS) after the launch of the WIND satellite. Most
  of these type II bursts were accompanied by type III bursts. We
  have positively identified the solar flares associated with all the
  events. When we examined the WIND Radio and Plasma waves (WAVES) data,
  we found the following: (i) Most of the metric (Hiraiso) type III bursts
  have counterparts in the WAVES data; (ii) None of the metric type II
  bursts have counterparts in the WAVES data. This result suggest that
  coronal shocks responsible for metric type II bursts are blast waves
  which decay rapidly within the inner corona while the electron beams
  producing type III bursts continue to propagate to the IP medium.

---------------------------------------------------------
Title: Polarization of Microwaves Emitted From A Bipolar Active Region
Authors: Lee, Jeongwoo; White, Stephen; Gopalswamy, N.; Kundu, M. R.
1996AAS...188.3603L    Altcode: 1996BAAS...28R.873L
  High resolution microwave maps of a complex bipolar active region,
  AR6615, were obtained using the VLA on 1991 May 7 at three frequencies,
  4.9 GHz, 8.4 GHz, and 15 GHz. Comparison of this microwave observation
  with Big Bear magnetogram suggests that inversion and depolarization of
  microwave emission must have occurred at different sites of the active
  region depending on frequency. For quantitative interpretation of the
  polarization data, we constructed the coronal magnetic fields above
  the active region using the potential field extrapolation. In the
  model, we identified the quasi-transverse (QT) surface across which
  change of the polarization may occur. It is found that the required
  topology of the QT surface to explain the observed polarization
  is correctly predicted by the potential field model, although the
  locations of the 15 GHz gyroresonance sources required a nonlinear
  force-free field extrapolation in part. With the calculation of the mode
  coupling coefficient along the QT surface, we were able to locate the
  region of depolarization above a strong sunspot, consistent with the
  observation. We also discuss the appropriate theoretical gyroresonant
  opacity for waves propagating perpendicular to the magnetic fields,
  as needed to understand the observed polarization across the magnetic
  neutral line. Applicability of the present results to study of the
  coronal magnetic structure above complex bipolar regions, in general,
  is briefly discussed.

---------------------------------------------------------
Title: A Multi Wavelength Study of Active Region Development
Authors: Lara, A.; Gopalswamy, N.; Kundu, M. R.; Perez-Enriquez, R.;
   Koshiishi, H.; Enome, S.
1996AAS...188.3601L    Altcode: 1996BAAS...28Q.873L
  We report on a study of the evolution of several active regions during
  1993 April 17-28 using data obtained at multiple wavelengths that
  probe various heights of the active region corona. We use simultaneous
  microwave (1.5 and 17 GHz) and Soft X-ray images obtained by the
  Very Large Array (VLA), the Nobeyama Radio Heliograph (NRH) and the
  Soft X-ray Telescope (SXT) on board the Yohkoh spacecraft. We also
  use photospheric magnetograms from Kitt Peak National Observatory
  to study the development of Solar Active Regions. We have followed
  the development of various observed parameters such as brightness
  temperature and polarization using radio images. The X-ray data were
  used to track the development of density and temperature of active
  regions. Using the fact that the quiet active region radiation is
  thermal and adopting proper emission mechanism at each frequency
  domain, we construct a consistent picture for the three dimensional
  structure of the active regions. Particular attention has been paid to
  the mode coupling observed at 17 GHz while the active regions crossed
  the solar disk.

---------------------------------------------------------
Title: Coronal Disconnection Events and Metric Radio Emisison
Authors: Gopalswamy, N.
1996Ap&SS.243..129G    Altcode: 1996IAUCo.154..129G
  We review the existing literature on the coronal disconnection events
  (CDEs) and discuss the importance of these events in understanding
  coronal structures. We discuss the possible radio signatures of the
  CDEs and how they may be observed by radio instruments.

---------------------------------------------------------
Title: Detection of Large-Scale Radio Structure and Plasma Flow
    during a Solar Bright Point Flare
Authors: Gopalswamy, N.; Kundu, M. R.; Hanaoka, Y.; Enome, S.; Lemen,
   J. R.
1996ApJ...457L.117G    Altcode:
  We report on the detection of a large-scale radio structure and
  plasma flow associated with a bright point flare observed on 1993
  July 11. The bright point (BP) flare was simultaneously imaged by the
  Nobeyama radioheliograph at 17 GHz and the Soft X-Ray Telescope on board
  the Yohkoh mission. The microwave emission consists of a large-scale
  structure and a compact moving source. The large-scale component seems
  to be the radio counterpart of large-scale loop structures sometimes
  observed in association with BP flares in X-rays. The compact source
  moved from the location of the X-ray BP flare with a speed of about 60
  km s-1, which suggests a plasma flow. Spatial comparison between X-ray
  and radio data shows that the BP flare had different manifestations in
  the two wavelength domains. The emission peaks in the two wavelength
  domains did not coincide, which suggests cool plasma flow along the
  large-scale radio structure. We were able to determine the temperature
  and emission measure of the BP flare plasma from the X-ray data,
  and thus we computed the expected radio flux from the X-ray--emitting
  plasma. We found that the computed radio flux was much smaller than
  the total observed radio flux.

---------------------------------------------------------
Title: VLA Observations of a Solar Active Region at 6.2 and 3.5 CM
    Wavelength Compared with Model Calculations
Authors: Hildebrandt, J.; Kruger, A.; Gopalswamy, N.; Raulin, J. -P.;
   Kundu, M. R.
1996ASPC...93..369H    Altcode: 1996ress.conf..369H
  No abstract at ADS

---------------------------------------------------------
Title: Three Part Structure of a CME Revealed by X-Ray and Microwave
    Observations
Authors: Gopalswamy, N.; Kundu, M. R.; Lara, A.; Hanaoka, Y.; Enome,
   S.; Lemen, J. R.; Akioka, M.
1996ASPC..111..393G    Altcode: 1997ASPC..111..393G
  The authors present X-ray (Yohkoh/SXT) and microwave (17 GHz Nobeyama)
  observations of the 1993 July 10 - 11 CME. During this event, all the
  substructures of a classical CME are revealed: frontal loop in X-rays,
  prominence core in microwaves, dark cavity between prominence and
  frontal loop in X-rays, and arcade structure beneath the prominence
  in X-rays.

---------------------------------------------------------
Title: A Study of Active Region Magnetic Field Structure Using
    VLA-Radio YOHKOH X-Ray and Mess-Optical Observations
Authors: Gopalswamy, N.
1995JApAS..16..381G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: VLA and YOHKOH Observations of an M1.5 Flare
Authors: Gopalswamy, N.; Raulin, J. -P.; Kundu, M. R.; Nitta, N.;
   Lemen, J. R.; Herrmann, R.; Zarro, D.; Kosugi, T.
1995ApJ...455..715G    Altcode:
  A major solar flare (X-ray importance M1.5 and optical importance SB)
  was fully observed by the Very Large Array and the Yohkoh mission on
  1993 April 22. Both thermal and nonthermal emissions were observed
  in radio. In soft X-rays, the flare was confined to a compact region
  in an arcade. In hard X-rays, there were two prominent footpoints,
  coincident in projection with the soft X-ray footpoints and located
  on either side of the magnetic neutral line inferred from photospheric
  magnetograms The Yohkoh Bent Crystal Spectrometer (B CS) data provided
  important context information which was helpful in cross-checking the
  quantitative agreement between the radio and X-ray data. The microwave
  spectrum peaked around 10 GHz and showed Razin suppression in the
  beginning. Later on, the low-frequency spectral index dropped to a
  value of 2, suggesting thermal emission. The VLA images of the flare at
  1.5 GHz show that the flare emission started as a single source above
  one footpoint; later on, the emission centroid moved toward the soft
  X-ray structure to finally become cospatial with the latter. The two
  locations of the 20 cm source corresponded to nonthermal (footpoint
  source) and thermal (source cospatial with the soft X-ray structure)
  emissions. We performed temperature and emission measure analysis of
  the X-ray data (SXT, BCS, and HXT) and used them as input to determine
  the expected radio emission. While there is morphological agreement
  between the radio and soft X-ray structures in the thermal phase,
  the 20 cm brightness temperature shows quantitative agreement with
  temperature derived from the BCS data. We were able to identify
  three emission mechanisms contributing to the 20 cm radio emission
  at different times without any ad hoc assumption regarding emission
  mechanisms. Razin-suppressed nonthermal gyroresonance emission,
  plasma emission, and thermal free-free emission seem to be operating
  and are found to be consistent with the plasma parameters derived
  from the X-ray data. The magnetic field structure in the flaring
  region showed differences before and after the flare as traced b soft
  X-ray structures in the flaring region and confirmed by 20 cm radio
  images. The superhot component with a temperature of 32 MK was observed
  in hard X-ray images and in light curves during the impulsive phase of
  the flare with possible radio signatures at 20 cm wavelength. We derived
  the physical parameters of the flaring plasma, the magnetic field,
  and the characteristics of nonthermal particles in the flaring region.

---------------------------------------------------------
Title: Radio Counterpart of an X-ray Bright Point Flare
Authors: Gopalswamy, N.; Kundu, M. R.; Hanaoka, Y.; Enome, S.; Lemen,
   J. R.
1995SPD....26.1317G    Altcode: 1995BAAS...27Q.991G
  No abstract at ADS

---------------------------------------------------------
Title: Surprises in the Radio Signatures of CMEs
Authors: Gopalswamy, N.; Kundu, M. R.
1995LNP...444..223G    Altcode: 1995cmer.conf..223G
  We discuss several results regarding the relationship between coronal
  mass ejections (CMEs) and metric radio emissions which have changed our
  understanding of these phenomena considerably. Imaging observations
  of metric radio emissions along with coronagraph observations have
  been used to obtain these results. We consider the following: (i) Why
  slow CMEs are associated with metric type IV radio emission contrary
  to the earlier belief, (ii) Why shocks piston driven by the CMEs are
  not seen in the solar corona, (iii) Thermal radio emission from the
  CMEs and their implications to CME-flare relationship and (iv) Radio
  signatures of coronas disconnection events.

---------------------------------------------------------
Title: Polarization Features of Solar Radio Emission and Possible
    Existence of Current Sheets in Active Regions
Authors: Gopalswamy, N.; Zheleznyakov, V. V.; White, S. M.; Kundu,
   M. R.
1994SoPh..155..339G    Altcode:
  We show that it is possible to account for the polarization features
  of solar radio emission provided the linear mode coupling theory is
  properly applied and the presence of current sheets in the corona
  is taken into account. We present a schematic model, including a
  current sheet that can explain the polarization features of both the
  low frequency slowly varying component and the bipolar noise storm
  radiation; the two radiations face similar propagation conditions
  through a current sheet and hence display similar polarization
  behavior. We discuss the applications of the linear mode coupling
  theory to the following types of solar radio emission: the slowly
  varying component, the microwave radio bursts, metric type U bursts,
  and bipolar noise storms.

---------------------------------------------------------
Title: Transient Microwave Brightenings in Solar Active Regions:
    Comparison between VLA and YOHKOH Observations
Authors: Gopalswamy, N.; Payne, T. E. W.; Schmahl, E. J.; Kundu, M. R.;
   Lemen, J. R.; Strong, K. T.; Canfield, R. C.; de La Beaujardiere, J.
1994ApJ...437..522G    Altcode:
  We report observations of transient microwave (2 cm) brightenings
  and their relationship with brightenings in soft X-rays. The peak
  flux of the microwave brightenings observed by the Very Large Array
  (VLA) is smaller than the previously reported fluxes by two orders
  of magnitude. The microwave sources were highly polarized (up to
  100%) and were situated on the periphery of a sunspot umbra. Among
  the many transients observed in X-rays by Yohkoh, two were observed
  simultaneously in microwaves. The microwave sources were found to
  be closer to the umbra of the sunspot than were the X-ray loops. It
  seems that the microwave sources are located at the footpoints of
  the looplike X-ray transients. Using the combined VLA, Yohkoh, and
  Mees data set, we determine the physical parameters of the loop in
  which the brightenings occur. We find that an increase in emission
  measure accompanied by small-scale heating can account for the X-ray
  brightening. The microwave emission can be interpreted as thermal
  gyroresonance or nonthermal gyrosynchrotron processes during the X-ray
  brightening. The magnetic field in the microwave-source region is
  found to be 1200-1800 G. The observations also provide evidence for
  temperature gradient in the coronal loops.

---------------------------------------------------------
Title: Study of Active Region Magnetic Field Structures Using VLA
    Radio, YOHKOH X-ray and MEES Optical Observations
Authors: Gopalswamy, N.; Schmahl, E. J.; Kundu, M. R.; Lemen, J. R.;
   Strong, K. T.; Canfield, R. C.; de La Beaujardiere, J.
1994kofu.symp..347G    Altcode:
  We report on the observation of compact magnetic flux tubes from the
  boundary between the umbra and penumbra of a large sunspot in AR 7135
  on April 24, 1992. The structure and geometry of one such flux tube
  was determined using the coordinated observations obtained by the
  Very Large Array, the Yohkoh Soft X-ray Telescope and the Mees Solar
  Observatory. From radio observations we infer that the magnetic field
  of the flux tube at the spot-side footpoint is ~ 1300-1800 G.

---------------------------------------------------------
Title: Nonthermal Radio Emission Associated with a Coronal
    Disconnection Event
Authors: Gopalswamy, N.; Kundu, M. R.; St. Cyr, O. C.
1994ApJ...424L.135G    Altcode:
  We have found possible radio signatures of a coronal disconnection event
  observed by the Solar Maximum Mission Coronagraph/Polarimeter. The
  radio emission seems to be produced by charged particles accelerated
  during the same reconnection process which is responsible for the
  disconnection event. We discuss the implications of the radio emission
  characteristics to the reconnection process.

---------------------------------------------------------
Title: Three dimensional coronal structures using clark lake
    observations
Authors: Schmahl, E. J.; Gopalswamy, N.; Kundu, M. R.
1994AdSpR..14d..65S    Altcode: 1994AdSpR..14...65S
  Throughout the quiet-Sun years 1982-1987, the Clark Lake Radioheliograph
  mapped the solar corona on a daily basis at frequencies from 30 to
  100 MHz. The Clark Lake maps show a variety of features which we have
  analyzed quantitatively. Among the features are coronal streamers,
  which appear to cross the solar disk during a solar rotation. We have
  modeled the streamers with various geometrics and density profiles,
  and computed ray-tracing images for comparison with the CLRO maps. These
  models produced estimates of density and spatial scales in 3 dimensions
  for the streamers. We discuss the significance of these estimates and
  compare them with inferences made from optical observations. One of
  the possible conclusions we draw from these comparisons is that there
  are unresolved structures in stremers, not observable optically in
  the limb data.

---------------------------------------------------------
Title: Three Dimensional Coronal Structures Using Clark-Lake
    Observations
Authors: Schmahl, E. J.; Gopalswamy, N.; Kundu, M. R.
1994SoPh..150..325S    Altcode:
  We have undertaken a study of coronal features observed at
  meter-decameter wavelengths using the Clark Lake radioheliograph. Among
  the coronal structures we have studied are the radio manifestations of
  coronal streamers on the solar disk and above the solar limb. We have
  analyzed the radio data quantitatively, using ray-tracing models for
  comparison with the maps. Our study provides information about the
  streamers' three-dimensional shapes, scales, and density profiles,
  for comparison with related observations using white-light coronagraphs.

---------------------------------------------------------
Title: Non-radial magnetic field structures in the solar corona
Authors: Gopalswamy, N.; Kundu, M. R.; Raoult, A.; Pick, M.
1994SoPh..150..317G    Altcode:
  We report on the structure and geometry of coronal magnetic fields
  inferred from the observations of meter-decimeter type III and moving
  type IV radio bursts, associated with a Hα flare. This is the first
  report of type III radio bursts from the Nançay radioheliograph after
  it acquired the two-dimensional multifrequency capability. Dispersion of
  the radio source positions with frequency suggests that open and closed
  field lines are considerably inclined to the radial direction which is
  consistent with the connectivity observed in the magnetogram. We suggest
  that multiple arch systems are involved in the type IV emission. From
  the polarization and dispersion characteristics of the type IV source,
  we infer that the emission is due to fundamental plasma emission.

---------------------------------------------------------
Title: Solar Simple Bursts Observed with High Spectral Resolution
    in the 18--23 GHz Range
Authors: Sawant, H. S.; Rosa, R. R.; Cecatto, J. R.; Gopalswamy, N.
1994ApJS...90..693S    Altcode: 1994IAUCo.142..693S
  For the first time, solar bursts in the frequency range of
  (18-23) GHz have been observed with high-time (0.6-1.2 s) and
  high-frequency resolution (1 GHz), by using the Itapetinga 13.7 m
  diameter antenna. Here, we investigate the microwave type 'simple
  low level (less than 10 SFU) bursts' associated with the impulsive
  phase of solar flares. Observed properties of these simple bursts are:
  rise time t<SUB>r</SUB> approximately 3 s, decay time t<SUB>d</SUB>
  approximately 5 s and spectral index ranging between -1 and -4. These
  bursts were found to be associated with SF or SN flares as seen in
  H(alpha). The above properties suggest that they are likely to be a
  microwave counterpart of elementary flare bursts. In the majority of
  the cases the spectral evolution is soft-hard-soft. This suggests a
  nonthermal gyrosynchrotron mechanism for generating these elementary
  flare bursts. Estimated parameters of these simple burst sources are
  height (h approximately 2400 km), electron density (N<SUB>epsilon</SUB>
  is less than 8.8 x 10<SUP>9</SUP>/cu cm.), and magnetic field (B
  approximately 300 G).

---------------------------------------------------------
Title: Millimeter, Microwave, Hard X-Ray, and Soft X-Ray Observations
    of Energetic Electron Populations in Solar Flares
Authors: Kundu, M. R.; White, S. M.; Gopalswamy, N.; Lim, J.
1994ApJS...90..599K    Altcode: 1994IAUCo.142..599K
  We present comparisons of multiwavelength data for a number of solar
  flares observed during the major campaign of 1991 June. The different
  wavelengths are diagnostics of energetic electrons in different energy
  ranges: soft X-rays are produced by electrons with energies typically
  below 10 keV, hard X-rays by electrons with energies in the range
  10-200 keV, microwaves by electrons in the range 100 keV-1 MeV, and
  millimeter-wavelength emission by electrons with energies of 0.5 MeV
  and above. The flares in the 1991 June active period were remarkable in
  two ways: all have very high turnover frequencies in their microwave
  spectra, and very soft hard X-ray spectra. The sensitivity of the
  microwave and millimeter data permit us to study the more energetic
  (greater than 0.3 MeV) electrons even in small flares, where their
  high-energy bremsstrahlung is too weak for present detectors. The
  millimeter data show delays in the onset of emission with respect to
  the emissions associated with lower energy electrons and differences in
  time profiles, energy spectral indices incompatible with those implied
  by the hard X-ray data, and a range of variability of the peak flux in
  the impulsive phase when compared with the peak hard X-ray flux which
  is two orders of magnitude larger than the corresponding variability
  in the peak microwave flux. All these results suggest that the hard
  X-ray-emitting electrons and those at higher energies which produce
  millimeter emission must be regarded as separate populations. This has
  implications for the well-known 'number problem' found previously when
  comparing the numbers of non thermal electrons required to produce
  the hard X-ray and radio emissions.

---------------------------------------------------------
Title: A Study of Active Region Magnetic Fields Using Radio, X-ray
    and Optical Observations
Authors: Gopalswamy, N.
1994ASPC...68..395G    Altcode: 1994sare.conf..395G
  No abstract at ADS

---------------------------------------------------------
Title: Interferometry of Solar Flares at 3-mm Wavelength
Authors: Kundu, M. R.; White, S. M.; Gopalswamy, N.; Lim, J.
1994IAUS..154..131K    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: VLA Observations of a High Coronal Flare
Authors: Raulin, J. P.; Gopalswamy, N.; Kundu, M. R.; Nitta, N.
1993AAS...183.0706R    Altcode: 1993BAAS...25.1300R
  We present radio observations of a coronal flare which occurrred on 1993
  April 22, in a weak magnetic field region to the west of AR 7477. The
  observations were made by the Very Large Array (VLA) at 20 and 90
  cm. The event consists of bright (brightness temperature of 10(10) K)
  unpolarized bursts, followed by a longlasting unpolarized continuum with
  moderately high brightness temperature (2-3 10(9) K) in the high corona
  (90 cm observations). The low coronal counterpart of this flare is a
  weak and moderatly polarized 20 cm radio emission. Full disk Yohkoh
  images show that the corresponding radio emission is located in or
  above magnetic loops connecting AR 7477 and its neighborhood. The
  presence of permanent and non-varying noise storm associated with
  AR 7477 seems to indicate that the overall magnetic field structure
  of the active region is unaffected by the flare. The coronal radio
  source which is indicative of acceleration of electrons to nonthermal
  energies, is not associated with major Hα emissio n nor with bright
  X ray emission. The absence of any detectable circular polarization,
  as well as the high brightness temperature, seems to indicate that
  the 90 cm emission is second harmonic plasma emission.

---------------------------------------------------------
Title: Variability in Sunspot Associated Microwave Emission: Umbral
    Oscillations?
Authors: Gopalswamy, N.; Schmahl, E. J.; Kundu, M. R.
1993AAS...183.6808G    Altcode: 1993BAAS...25.1396G
  We report on microwave observations of sunspot associated emission
  that shows variability over a time scale of minutes. To our knowledge,
  this is the first time such rapid variability has been observed in
  microwave radiation from a sunspot. These observations were obtained
  by the Very Large Array (VLA) on April 24, 1992 at 2cm. The radio
  emission from the sunspot umbra was in the form of several compact
  sources with a size less than 4 arcsec. The time evolution of the peak
  flux of these sources showed significant time variations which were
  sometimes periodic. The period of these ocillations was approximately
  3 min, similar to that of intensity and Doppler shift oscillations
  observed in optically thin, transition region lines such as C IV
  (1548.19 Angstroms) in sunspot umbrae. There were also morphological
  changes in the extended sunspot emission over which the compact sources
  were superposed. We also observed the appearance of new compact sources
  within the umbra where there was reduced emission before. The brightness
  temperatures of these compact sources were in the range (1-5)times 10(5)
  K. We explore possible interpretations of the time variability.

---------------------------------------------------------
Title: Structure of a fast coronal mass ejection from radio
    observations.
Authors: Gopalswamy, N.; Kundu, M. R.
1993AdSpR..13i..75G    Altcode: 1993AdSpR..13R..75G
  The authors investigate the thermal structure of a coronal mass ejection
  (CME) in meter-dekameter wavelengths and compare it with the optical
  evidence. The multifrequency observations enable us to infer the three
  dimensional structure of the CME. The authors estimated the mass of
  the CME and found to be in reasonable agreement with the range of
  values obtained from white light observations.

---------------------------------------------------------
Title: Interferometric observations of solar flares at 3 mm wavelength
Authors: Kundu, M. R.; White, S. M.; Gopalswamy, N.; Lim, J.
1993AdSpR..13i.289K    Altcode: 1993AdSpR..13..289K
  We report on the observations of a number of flares at a wavelength of
  3.5 mm during the 1991 June solar campaign. Many flares, including
  small ones, show an impulsive phase at milllimeter wavelengths
  which indicates the presence of MeV electrons, and the millimeter
  observations are far more sensitive to such electrons than are current
  γ-ray detectors. However, these energetic electrons do not always show
  a good correlation with the lower-energy electrons which produce hard
  X-rays below 100 keV. The production efficiency of MeV electrons seems
  to vary considerably from flare to flare. An extended phase similar to
  the soft X-ray behaviour is also seen at millimeter wavelengths, which
  we attribute to dense hot material radiating thermal bremsstrahlung. In
  the impulsive onset the millimeter emission seems to be consistently
  delayed with respect to the hard X-rays.

---------------------------------------------------------
Title: Simultaneous Observations of Solar Plage with the Solar
    Extreme Ultraviolet Rocket Telescope and Spectrograph (SERTS),
    the VLA, and the Kitt Peak Magnetograph
Authors: Brosius, Jeffrey W.; Davila, Joseph M.; Thompson, William T.;
   Thomas, Roger J.; Holman, Gordon D.; Gopalswamy, N.; White, Stephen
   M.; Kundu, Mukul R.; Jones, Harrison P.
1993ApJ...411..410B    Altcode:
  We obtained simultaneous images of solar plage on 1991, May 7
  with SERTS, the VLA,4 and the NASA/National Solar Observatory
  spectromagnetograph at the NSO/Kitt Peak Vacuum Telescope. Using
  intensity ratios of Fe XVI to Fe XV emission lines, we find that the
  coronal plasma temperature is (2.3-2.9) x 10 exp 6 K throughout the
  region. The column emission measure ranges from 2.5 x 10 exp 27 to
  l.3 x 10 exp 28 cm exp -5. The calculated structure and intensity
  of the 20 cm wavelength thermal bremsstrahlung emission from the hot
  plasma observed by SERTS is quite similar to the observed structure and
  intensity of the 20 cm microwave emission observed by the VLA. Using
  the Meyer (1991, 1992) revised coronal iron abundance, we find no
  evidence either for cool absorbing plasma or for contributions from
  thermal gyroemission. Using the observed microwave polarization and the
  SERTS plasma parameters, we calculate a map of the coronal longitudinal
  magnetic field. The resulting values, about 30-60 G, are comparable
  to extrapolated values of the potential field at heights of 5000 and
  10,000 km.

---------------------------------------------------------
Title: A Study of the Solar Active Regions Using Simultaneous VLA
and Yohkoh Soft X-ray Imaging: CoMStOC `92
Authors: Gopalswamy, N.; White, S. M.; Kundu, M. R.; Lemen, J. R.;
   Strong, K. T.; Schmelz, J. T.
1993BAAS...25R1213G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Hard X-ray and Radio Spectra for Solar Flares from AR 6659
Authors: White, S. M.; Murphy, R.; Schwartz, R. A.; Kundu, M. R.;
   Gopalswamy, N.; Lim, J.
1993BAAS...25Q1222W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: VLA and Yohkoh Observations of an M1.5 Flare
Authors: Gopalswamy, N.; Kundu, M. R.; Lemen, J. R.; Nitta, N.;
   Strong, K. T.
1993BAAS...25.1186G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: VLA, OVRO, Yohkoh and Optical Observations During CoMStOC
Authors: Schmahl, E. J.; Gopalswamy, N.; Kundu, M. R.; Lemen, J.;
   Strong, K. T.; de La Beaujardiere, J.
1993BAAS...25.1213S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Solar Coronal Plasma and Magnetic Field Diagnostics Using
    SERTS and Coordinated VLA Observations
Authors: Brosius, J. W.; Davila, J. M.; Thompson, W. T.; Thomas, R. J.;
   Holman, G. D.; Gopalswamy, N.; White, S. M.; Kundu, M. R.; Jones, H. P.
1993BAAS...25.1224B    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: A Multiwavelength Portrait of a Solar Active Region
Authors: White, S. M.; Kundu, M. R.; Gopalswamy, N.
1993BAAS...25.1183W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Thermal and nonthermal emissions during a coronal mass ejection
Authors: Gopalswamy, N.; Kundu, M. R.
1993SoPh..143..327G    Altcode:
  We report on the thermal and nonthermal radio emissions from a coronal
  mass ejection (CME) observed at meter-decameter wavelengths using the
  Clark Lake multifrequency radioheliograph. From white-light observations
  of the Solar Maximum Mission Coronagraph/Polarimeter instrument the CME
  was found to have a speed of ∼ 450 km s<SUP>−1</SUP>. Since there
  was no nonthermal radio emission in the beginning of the event and the
  one which occurred later was quite weak, we were able to observe the
  thermal structure of the CME in radio. Type III bursts and a nonthermal
  continuum started several minutes after the CME onset. We use the radio
  and optical observations to show that the CME was not driven by the
  flare. We investigate the thermal structure and geometry of the mass
  ejection in radio and compare it with the optical evidence. Finally
  we develop a schematic model of the event and point out that particle
  acceleration high in the corona is possible.

---------------------------------------------------------
Title: A new investigation of microbursts at meter-decameter
    wavelengths
Authors: Subramanian, K. R.; Gopalswamy, N.; Sastry, Ch. V.
1993SoPh..143..301S    Altcode:
  We report on a new investigation of microbursts at meter-decameter
  wavelengths observed using the Broad Band Array at Gauribidanur
  Radio Observatory. This is an independent set of observations of
  microbursts: previous observations had been obtained only by the Clark
  Lake multifrequency radioheliograph. We confirm several properties
  of microbursts reported earlier. In addition, we have studied some
  new properties of microbursts such as time profile characteristics,
  flux density and energy spectra for comparison with the corresponding
  properties of normal type III bursts. The present study supports
  the idea that the microbursts and the normal type III bursts are
  generated by electron beams of similar characteristics. We interpret
  the low brightness temperature of microbursts as follows: plasma waves
  generated by the electron beams through beam-plasma instability are
  quickly isotropized as they scatter on the density fluctuations in
  the corona. The resulting low levels of plasma waves are converted
  into transverse radiation of low brightness temperature. One important
  consequence of the isotropization is that the second harmonic plasma
  emission dominates the fundamental and hence the microbursts are
  expected to be predominantly a harmonic plasma emission.

---------------------------------------------------------
Title: Analysis of EUV, Microwave and Magnetic Field Observations
    of Solar Plage
Authors: Brosius, J. W.; Davila, J. M.; Jones, H. P.; Thompson, W. T.;
   Thomas, R. J.; Holman, G. D.; White, S. W.; Gopalswamy, N.; Kundu,
   M. R.
1993ASPC...46..291B    Altcode: 1993mvfs.conf..291B; 1993IAUCo.141..291B
  No abstract at ADS

---------------------------------------------------------
Title: Plasma Emission from Isotropic Langmuir Turbulence: Are Radio
    Microbursts Structureless?
Authors: Gopalswamy, N.
1993ApJ...402..326G    Altcode:
  The brightness temperature of radio emission through the fundamental and
  second harmonic plasma processes is determined for isotropic Langmuir
  waves of low-energy density in order to account for the microbursts
  at meter-dekameter wavelengths. The probable cause for low levels of
  Langmuir turbulence is the presence of isotropic density fluctuations
  in the corona which isotropize the beam-generated Langmuir waves. We
  determined the energy density of Langmuir waves attainable from
  the beam-plasma instability in the presence of isotropic density
  fluctuations. Since the electron density fluctuations isotropize
  the beam-generated plasma waves, the head-on collision of plasma
  waves becomes efficient to produce the second harmonic plasma
  emission. For reasonable beam parameters, the brightness temmperature
  of the fundamental never exceeds 10 exp 6 K, while the second harmonic
  covers the observed range of microburst brightness temperatures. Thus,
  the microbursts are predominantly at second harmonic. This leads to an
  important conclusion that the microbursts are structureless, similar
  to a population of normal type III bursts of low polarization with no
  fundamental-harmonic structure.

---------------------------------------------------------
Title: Are coronal type II shocks piston driven?
Authors: Gopalswamy, N.; Kundu, M. R.
1992AIPC..264..257G    Altcode: 1992pacp.work..257G
  Flare blast waves and shocks piston driven by coronal mass ejections
  (CMEs) have been proposed to be responsible for generating type II
  radio bursts in the solar corona. The idea for piston-driven shocks
  came primarily from temporal association of shocks and CMEs. Our
  compilation of CME events with simultaneous radio observations with
  positional information supports idea of flare blast waves.

---------------------------------------------------------
Title: Analysis of EUV, Microwave, and Magnetic Field Observations
    of a Solar Active Region
Authors: Brosius, J. W.; Davila, J. M.; Jones, H. P.; Thompson, W. T.;
   White, S. M.; Gopalswamy, N.; Kundu, M. R.
1992AAS...180.4002B    Altcode: 1992BAAS...24R.792B
  No abstract at ADS

---------------------------------------------------------
Title: Simultaneous Hard X-ray, Soft X-ray, Millimeter and Microwave
    Observations of a Solar Flare
Authors: White, S. M.; Kundu, M. R.; Lim, J.; Gopalswamy, N.
1992AAS...180.4504W    Altcode: 1992BAAS...24..802W
  We present non-imaging data across a wide range of wavelengths for a
  solar flare which occurred on 1991 June 13. This flare is of interest
  because it shows a spike in hard X-rays at the beginning of the event
  which had a relatively hard X-ray spectrum, and was followed by a much
  softer impulsive phase. We present the BATSE and OSSE observations
  (from the Gamma Ray Observatory): the former have good time resolution,
  while the latter provide well-resolved spectral information. These are
  contrasted with the GOES soft-X-ray data on the hot thermal component in
  the corona, and radio observations up to 86 GHz which are sensitive to
  both the nonthermal and thermal components of the flare. The 86 GHz data
  from the BIMA millimeter interferometer show a spike in the impulsive
  phase coincident with the hard X-ray spike above 100 keV, as well as
  a long-duration thermal phase which appears to be consistent with an
  origin in the same material seen by GOES. We discuss the implications
  of the observations for particle acceleration in this flare.

---------------------------------------------------------
Title: Estimation of the Mass of a Coronal Mass Ejection from Radio
    Observations
Authors: Gopalswamy, N.; Kundu, M. R.
1992ApJ...390L..37G    Altcode:
  The mass of a coronal mass ejection (CME) is estimated using
  meter-decametric observations obtained with the Clark Lake
  multifrequency radioheliograph. Mass estimates in the past were made
  using coronagraph and white-light photometer observations. Since
  the radiation at radio and optical wavelength regimes has different
  physical origins, the radio method can provide an independent check
  on the mass estimates. The estimate of the 1986 February 16 CME using
  the radio method is close to the average value of CME masses reported
  in the literature.

---------------------------------------------------------
Title: Are Microbursts Structureless?
Authors: Gopalswamy, N.
1992AAS...180.5601G    Altcode: 1992BAAS...24Q.820G
  Microbursts are of lowest brightness temperature of all the radio bursts
  in the meter-decameter wavelength regime. Since the low brightness
  temperature is a consequence of low level of Langmuir turbulence, it
  was thought that a nonlinear process such as the second harmonic plasma
  emission would be unimportant. The probable cause for low levels of
  Langmuir turbulence is the presence of isotropic density fluctuations
  in the corona which isotropize the beam-generated Langmuir waves. The
  isotropy of the Langmuir turbulence favors the head-on collision of
  plasma waves needed to satisfy the kinematic conditions of harmonic
  plasma emission. For reasonable beam parameters, we find that the
  second harmonic plasma emission always dominates; the fundamental
  brightness temperature never exceeds 10(6) K. Thus we conclude that
  the microbursts may be structureless. We also find that the microburst
  electron beams are no different from the normal type III electron beams.

---------------------------------------------------------
Title: High Dynamic Range Multifrequency Radio Observations of a
    Solar Active Region
Authors: White, S. M.; Kundu, M. R.; Gopalswamy, N.
1992ApJS...78..599W    Altcode:
  High-dynamic-range multifrequency radio observations of a solar active
  region are presented. The evolution of the region is followed at 5
  GHz as it rotates from the limb to disk center, and when it is at
  disk center, observations at 0.33, 1.5, 5, 8.4, and 15 GHz are used
  to analyze the distribution of density and magnetic field within
  the active region. A dynamic range of up to 1500 (at 8.4 GHz) was
  achieved because these data were well suited to the self-calibration
  technique. The signatures of both optically thick gyroresonance emission
  are unambiguously identified, and magnetic fields and optically thin
  thermal free-free emission are outlined. Images are compared at 5
  and 8.4 GHz in order to identify regions in the trailing part of
  the active region where optically thin four-harmonic gyroresonance
  emission is contributing to the observed brightness temperatures at
  5 GHz, indicating the presence of 450 G fields.

---------------------------------------------------------
Title: Millimeter and hard X-ray/γ-ray observations of solar flares
    during the June 91 GRO campaign.
Authors: Kundu, M. R.; White, S. M.; Gopalswamy, N.; Lim, J.
1992NASCP3137..502K    Altcode: 1992como.work..502K
  We have carried out high-spatial-resolution millimeter observations
  of solar flares using the Berkeley-Illinois-Maryland Array (BIMA). At
  the present time, BIMA consists of only three elements, which is
  not adequate for mapping highly variable solar phenomena, but is
  excellent for studies of the temporal structure of flares at millimeter
  wavelengths at several different spatial scales. We present BIMA
  observations made during the Gamma Ray Observatories (GRO)/Solar Max
  1991 campaign in Jun. 1991 when solar activity was unusually high. Our
  observations covered the period 8-9 Jun. 1991; this period overlapped
  the period 4-15 Jun. when the Compton Telescope made the Sun a target
  of opportunity because of the high level of solar activity.

---------------------------------------------------------
Title: Meter-decameter radio emission associated with a coronal
    mass ejection
Authors: Kundu, M. R.; Gopalswamy, N.
1992LNP...399..268K    Altcode: 1992esf..coll..268K; 1992LNP...399..268G; 1992IAUCo.133..268K
  A study of meter-dekameter radio emission associated with the 1986
  Feb 10 coronal Mass ejection event is presented here. The event
  was accompanied by a major flare (optical importance 1B and X-ray
  importance C9.6), preceded by a filament disappearance. Changes in
  the intensity of a pre-existing noise storm was observed during the
  onset of the flare. A flare continuum, a moving type IV, and a type
  II occurred during the event. The event was also associated with a
  strong hard X-ray burst. The speeds of moving type IV burst and CME
  were of the same order of 1600 kms -1, while the type II shock speed
  was 1900 kms -1. The positional data indicate that the moving type IV
  burst and the inferred type II shock had different trajectories. The
  moving type IV burst was confined to one leg of the CME while the
  type II shock was far ahead of the CME leading edge. We discuss the
  inferred relation among different entities such as the CME, type II
  shock, type IV plasmoid and the erupting filament.

---------------------------------------------------------
Title: Largescale Structures Associated with Eruptive Flares and
    Radio Waves
Authors: Gopalswamy, N.; Kundu, M. R.
1992LNP...399..207G    Altcode: 1992esf..coll..207G; 1992IAUCo.133..207G
  We review some recent results obtained from 2-dimensional imaging
  observations of the Sun using the Clark Lake multifrequency
  radioheliograph. The radioheliograph produced images of the Sun's
  corona on a daily basis at several frequencies within the range
  20-125 MHz during the period 1982-87. Using these images both large
  scale structures as well as transient phenomena such as bursts have
  been studied. In this paper we discuss the nature of radio emission
  associated with eruptive filaments and CMEs. It is possible to
  trace the structure of magnetic fields in the corona based on the
  multifrequency observations of moving type IV bursts at meter and
  decameter wavelengths. We illustrate this by discussing specific
  events. We discuss a rare case of the detection of thermal radio
  emission in association with a fast CME. We estimate the CME mass
  using spatially resolved radio data.

---------------------------------------------------------
Title: Large-Scale Features of the Sun at 20 Centimeter Wavelength
Authors: Gopalswamy, N.; White, S. M.; Kundu, M. R.
1991ApJ...379..366G    Altcode:
  Results are reported from an experimental study of the characteristics
  of large-scale coronal structures such as active regions, plages,
  filaments, and coronal holes using data obtained with the VLA
  at 1.5 GHz during the period September 11-17, 1988. The radio
  data were supplemented with He 10830- A, H-alpha, and Calcium-K
  spectroheliograms. A statistical analysis of some of the characteristics
  of the active regions is performed. Most of the active region sources
  were found to be about 100 arcsec in size, with bridges between regions
  common; lower brightness temperature regions showed a higher degree of
  polarization in general. The maximum polarization was found at the edge
  of active regions but well within the associated plages. The degree of
  polarization from bright active regions was small (not more than 20
  percent), in agreement with previous results. Evidence was found for
  compression of preexisting flux by the emerging flux from a new region,
  which took place in the apparent absence of magnetic reconnection.

---------------------------------------------------------
Title: Simultaneous EUV, Microwave, and Magnetic Field Observations
    of Solar Active Regions
Authors: Brosius, J. W.; Davila, J. M.; Thompson, W. T.; Gopalswamy,
   N.; White, S. M.; Jones, H. P.; Metcalf, T. R.
1991BAAS...23.1388B    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Coronal Magnetic Structures Observing Campaign. I. Simultaneous
    Microwave and Soft X-Ray Observations of Active Regions at the
    Solar Limb
Authors: Nitta, N.; White, S. M.; Kundu, M. R.; Gopalswamy, N.; Holman,
   G. D.; Brosius, J. W.; Schmelz, J. T.; Saba, J. L. R.; Strong, K. T.
1991ApJ...374..374N    Altcode:
  Using simultaneous microwave and soft X-ray measurements made with
  the Very Large Array (VLA) at 6 and 20 cm and the X-ray Polychromator
  (XRP) aboard the Solar Maximum Mission (SMM), we have studied two
  active regions near the solar limb. These observations were taken as
  part of the Coronal Magnetic Structures Observing Campaign (CoMStOC),
  a collaboration designed to study the magnetic field in the solar
  corona. The images in soft X-rays and at 20 cm wavelength are similar:
  both show peaks above the active regions and extended bridge of
  emission 200,000 km long connecting the two regions. The brightness
  temperature of the 20 cm emission is lower than that predicted from the
  X-ray emitting material, however; it can be attributed to free-free
  emission in cooler (&lt;10<SUP>6</SUP> K) plasma not visible to XRP,
  with an optical depth ∼1. The 6 cm emission is concentrated at lower
  altitudes and in a ∼160,000 km long bundle of loops in the northern
  active region. Comparison of the 6 cm map with the potential magnetic
  field lines computed from photospheric magnetic fields (measured 2 days
  earlier) indicates that the 6 cm emission is associated with fields
  of less than ∼200 G. Such fields would be too weak to attribute the
  observed 6 cm emission to gyroresonance radiation. Analysis of the
  6 cm loop bundle indicates that it is strongly asymmetric, with the
  magnetic field in the northern leg ∼2 times stronger than in the
  southern leg; the 6 cm emission most likely arises from a combination
  of hot ( ≥ 2 × 10<SUP>6</SUP> K) and cool plasmas, while the 20 cm
  emission becomes optically thick in the cooler (∼9 × 10<SUP>3</SUP>
  K) plasma. We estimate an Alfvén speed ∼7000 km s<SUP>-1</SUP>
  and ratio of electron gyrofrequency to plasma frequency ∼1.0 in the
  northern leg of the 6 cm loop.

---------------------------------------------------------
Title: Global Streamer Evolution
Authors: Thejappa, G.; Kundu, M. R.; Gopalswamy, N.
1991BAAS...23.1045T    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: VLA Observations of Radio Filaments
Authors: Gopalswamy, N.; White, S. M.; Kundu, M. R.
1991BAAS...23.1045G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Strong Magnetic Fields and Inhomogeneity in the Solar Corona
Authors: White, S. M.; Kundu, M. R.; Gopalswamy, N.
1991ApJ...366L..43W    Altcode:
  It is shown that fields of 1800 G can exist in the corona based
  on observations of gyroresonance emission at 15 GHz at coronal
  temperatures. The strong fields occur in a small source radiating
  in the extraordinary (x) mode over the penumbra of a large symmetric
  sunspot. The optically-thin ordinary mode emission from the region shows
  a nearby peak at only 36,000 K which may be due to a sunspot plume,
  and a hole over the umbra consistent with the expected low-density
  material there. The x-mode source is highly asymmetric, despite the
  apparent symmetry of the sunspot, and its appearance and location
  imply that the strongest magnetic fields in the corona are localized
  in a compact flux tube.

---------------------------------------------------------
Title: VLA Observations of Active Region 5555 During the 1st Max'91
    Campaign
Authors: Schmahl, E. J.; Gopalswamy, N.; Kundu, M. R.
1991max..conf...23S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Association of a Type IV Burst with a Slow CME
Authors: Gopalswamy, N.; Kundu, M. R.
1991max..conf..139G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Observation of an Unusually Fast Type IV Plasmoid
Authors: Gopalswamy, N.; Kundu, M. R.
1990ApJ...365L..31G    Altcode:
  A moving type IV burst of the 'isolated source' type has been detected
  whose out-of-plane speed, at 1600 km/sec, becomes about 2800 km/sec
  upon assumption of radial motion; this is twice as high as previously
  reported speeds for bursts of this type. While shock waves are known
  to have such high speeds, and a shock wave is likely to form ahead
  of a high-speed plasmoid, no radio signature has been observed for
  such a shock. This lack of shock detection may, however, be primarily
  due to poor observing conditions. Energetic electrons, trapped in an
  about 1.4 G magnetic field of the plasmoid, can adequately account
  for the emission.

---------------------------------------------------------
Title: Filament Eruption and Storm Radiation at Meter / Decameter
    Wavelengths
Authors: Kundu, M. R.; Gopalswamy, N.
1990SoPh..129..133K    Altcode:
  We report the study of a weak noise storm observed by the Clark Lake
  multifrequency radioheliograph at four frequencies. The noise storm
  onset was associated with a filament eruption and a gradual rise and
  fall in soft X-rays. We compare the noise storm emission with related
  emissions in other wavelengths to develop a composite scenario of
  the event. Using the properties of the quiet corona inferred from the
  simultaneously observed quiet-Sun radiation, we estimate the brightness
  temperature of the storm continuum, which seems to be consistent with
  the observations reported in Solar Geophysical Data. Superthermal
  particles with a temperature that is ten times the coronal electron
  temperature and a density of ∼ 10<SUP>−3</SUP> times the coronal
  density are adequate to explain the observed radiation. Since the noise
  storm observations were made at four frequencies, we were able to obtain
  a brightness temperature spectrum of the storm radiation. If the storm
  radiation is affected in the same way as the quiet-Sun emission by
  inhomogeneities, the observed spectrum can be interpreted as due to
  propagation effects. Since the Clark Lake instrument can observe both
  quiet Sun and weak bursts simultaneously, we were able to estimate
  the propagation effects from the quiet-Sun observations and use it to
  correct the brightness temperature of storm radiation.

---------------------------------------------------------
Title: Multiple Moving Magnetic Structures in the Solar Corona
Authors: Gopalswamy, N.; Kundu, M. R.
1990SoPh..128..377G    Altcode: 1990IAUCo.121P.377G
  We report the study of moving magnetic structures inferred from the
  observations of a moving type IV event with multiple sources. The
  ejection contains at least two moving radio emitting loops with
  different relative inclinations. The radio loops are located above
  multiple Hα flare loops in an active region near the limb. We
  investigate the relationship between the two systems of loops. The
  spatial, temporal and geometrical associations between the radio
  emission and near surface activities suggest a scenario similar to
  coronal mass ejection (CME) events, although no CME observations exist
  for the present event. From the observed characteristics, we find that
  the radio emission can be interpreted as Razin suppressed optically thin
  gyrosynchrotron emission from nonthermal particles of energy ∼ 100,
  keV and density ∼ 10<SUP>2</SUP>-10<SUP>5</SUP> cm<SUP>−3</SUP>
  in a magnetic field ≤ 2 G.

---------------------------------------------------------
Title: First High Spatial Resolution Interferometric Observations
    of Solar Flares at Millimeter Wavelengths
Authors: Kundu, M. R.; White, S. M.; Gopalswamy, N.; Bieging, J. H.;
   Hurford, G. J.
1990ApJ...358L..69K    Altcode:
  The first high spatial resolution interferometric observations
  of solar flares at millimeter wavelengths, carried out with the
  Berkeley-Illinois-Maryland Array are presented. The observations were
  made at 3.3 mm wavelength during the very active periods of March 1989,
  using one or three baselines with fringe spacings of 2-5 arcsec. The
  observations represent an improvement of an order of magnitude in
  both sensitivity and spatial resolution compared with previous solar
  observations at these wavelengths. It appears that millimeter burst
  sources are not much smaller than microwave sources. The most intense
  bursts imply brightness temperatures of over 10 to the 6th K and are due
  to nonthermal gyrosynchrotron emission or possibly thermal free-free
  emission. If the emission in the flash phase is predominantly due to
  gyrosynchrotron emission, thermal gyrosynchrotron models can be ruled
  out for the radio emission because the flux at millimeter wavelengths
  is too high.

---------------------------------------------------------
Title: Microbursts at Meter-Decameter Wavelengths
Authors: Thejappa, G.; Gopalswamy, N.; Kundu, M. R.
1990SoPh..127..165T    Altcode:
  We study the characteristics of microbursts using a large data base
  obtained with the multifrequency radioheliograph of the Clark Lake Radio
  Observatory. Most of the new observations were made during July 29,
  1985 to August 2, 1985; we also include for statistical studies the
  microburst data used in our earlier studies. We perform a statistical
  analysis of many characteristics such as frequency drift, source size
  and brightness temperature and compare them with the properties of
  normal type III bursts. We investigate the coronal structures and
  surface activities associated with some of the events. We find that
  (i) the brightness temperature is in the range 6 × 10<SUP>5</SUP>
  K to 6 × 10<SUP>7</SUP> K; (ii) the drift rate of the microbursts is
  slightly smaller than that of normal type III bursts, implying electron
  beams with speeds ∼0.2c.

---------------------------------------------------------
Title: A Note on the Emission Mechanism of Storm Radiation
Authors: Gopalswamy, N.
1990SoPh..126..367G    Altcode:
  A new mechanism has been proposed for the continuum and burst components
  of solar storm radiation by Genkin, Erukhimov, and Levin (1989a,
  b). In this paper, we point out that while bursts can be explained by
  the proposed mechanism of scattering on plasma turbulence generated
  density fluctuations, the continuum cannot be explained by sattering
  on thermal ion density fluctuations. The reason is, under the same
  coronal conditions, second harmonic emissions will dominate over
  the fundamental emission due to scattering on thermal ion density
  fluctuations in contradiction to observations. We also note that the
  range of plasma wave densities needed for this mechanism may not be
  realistic for the case of plasma wave generation due to loss cone
  instability. It is further argued that coalescence of plasma waves
  with low-frequency waves still seems to be the plausible mechanism.

---------------------------------------------------------
Title: CoMStOCI: Physical Properties of an Active Region Loop Observed
    at the Solar Limb
Authors: Holman, G. D.; Brosius, J. W.; Nitta, N.; White, S. M.; Kundu,
   M. R.; Gopalswamy, N.; Schmelz, J. T.; Saba, J. L. R.; Strong, K. T.
1990BAAS...22..899H    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Evolution of Active Regions at 20 cm
Authors: Gopalswamy, N.; White, S. M.; Kundu, M. R.
1990BAAS...22..795G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: High-Dynamic-Range Multifrequency Radio Observations of a
    Solar Active Region
Authors: White, S. M.; Kundu, M. R.; Gopalswamy, N.
1990BAAS...22R.794W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Millimeter-Interferometer Observations of Solar Flares
Authors: Kundu, M. R.; White, S. M.; Gopalswamy, N.; Bieging, J. H.;
   Hurford, G. J.
1990BAAS...22..823K    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: New Observations of Storm Radiation at Decameter Wavelengths
    and Their Interpretation
Authors: Thejappa, G.; Gopalswamy, N.; Kundu, M. R.
1990BAAS...22..794T    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Some Problems in Low Frequency Solar Radio Physics
Authors: Gopalswamy, N.; Kundu, M. R.
1990LNP...362...97G    Altcode: 1990lfas.work...97G
  Several important problems in solar radio physics can be attacked using
  the high spatial resolution observations from a low frequency space
  array, as the problem of ionospheric refraction does not exist. Noise
  storms are believed to occur in closed magnetic loops due to trapped
  superthermal particles. Recent radioheliograph observations suggest such
  a magnetic field topology up to altitudes of about 40 MHz emission. The
  problem of relative locations and sources of the storm continuum and
  bursts can be effectively studied by imaging them with higher spatial
  resolution. Interplanetary type II bursts are observed from heights
  above ~ 10 R while coronal type II bursts are observed from heights less
  than ~ 3 R. Observations filling this gap have important implications
  for the understanding of solar-terrestrial relations through shocks
  and mass ejections.

---------------------------------------------------------
Title: Microbursts at Meter-Decameter Wavelengths
Authors: Thejappa, G.; Gopalswamy, N.; Kundu, M. R.
1990IAUS..142..521T    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Clark-Lake Radio Observations of Coronal Mass Ejections
Authors: Gopalswamy, N.
1990IAUS..142..495G    Altcode:
  Some recent studies of mass ejections from the sun are reviewed
  using 2D imaging observations of the Clark Lake multifrequency
  radioheliograph. Radio signatures of both fast and slow coronal mass
  ejections (CMEs) have been observed. Using temporal and positional
  analysis of moving type-IV and type-II bursts, and white light CMEs
  it is found that the type II bursts and CMEs need not have a direct
  cause and effect relationship. Instead, the type II burst seems to
  be generated by a 'decoupled shock', probably due to an associated
  flare. The moving type IV burst requires nonthermal particles trapped
  in magnetic structures associated with the CME. Since nonthermal
  particles can be generated independent of the speed of CMEs, moving
  type IV bursts need not be associated only with fast CMEs. Specific
  examples are presented to support these views.

---------------------------------------------------------
Title: The Sun at the Vla's Metric and Decimetric Wavelengths
Authors: White, S. M.; Kundu, M. R.; Gopalswamy, N.; Schmahl, E. J.
1990IAUS..142..523W    Altcode:
  Preliminary results of solar observations at 0.333 and 1.5 GHz
  made with the VLA during the September 11-17, 1988 period are
  presented. Generally, there are few structural changes in the active
  region sources from one day to the next, suggesting that structural
  evolution is relatively slow. Contour maps at 1.5 GHz are presented
  for each of the four days. Two noise storms were present at 0.33 GHz
  all week and were highly polarized.

---------------------------------------------------------
Title: The Radio Signatures of a Slow Coronal Mass Ejection: Electron
    Acceleration at Slow-Mode Shocks?
Authors: Kundu, M.; Gopalswamy, N.; White, S.; Cargill, P.; Schmahl,
   E. J.; Hildner, E.
1989ApJ...347..505K    Altcode:
  The evolution of a coronal mass ejection (CME) event observed on
  February 17, 1985 is studied using two-dimensional radio imaging
  observations along with simultaneously obtained coronagraph
  observations. This event shows that a slow CME can be associated
  with type II and type IV radio bursts. The implications of the spatial
  association of the radio bursts with the CME are discussed. It is argued
  that the CME is due to an instability of the large-scale magnetic
  field in a helmet streamer and that the radio bursts are some of the
  responses to this instability. The new feature of this event is the
  clear association of the moving type IV burst with a CME traveling
  slower than the coronal Alfven speed. The structure of slow shocks
  driven by such a CME is discussed, and it is shown that shock drift
  and diffusive acceleration are ineffective. An acceleration mechanism
  involving current-driven lower hybrid waves is proposed.

---------------------------------------------------------
Title: Evidence for Noise Storm Emission by Superthermal Particles
    During a Filament Eruption
Authors: Gopalswamy, N.; Kundu, M. R.
1989BAAS...21.1146G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Radio Observations of Coronal Changes
Authors: Kundu, M. R.; Gopalswamy, N.
1989BAAS...21.1145K    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Microbursts at Meter-Decameter Wavelengths
Authors: Thejappa, G.; Gopalswamy, N.; Kundu, M. R.
1989BAAS...21.1145T    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The First Interferometric Observations with Arc-Second
    Resolution of Solar Radio Bursts at Millimeter Wavelengths
Authors: Kundu, M. R.; White, S. M.; Gopalswamy, N.; Bieging, J. H.
1989BAAS...21..861K    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Meter Wave Radio Signatures of Slow CME's and Coronal Streamer
    Evolution
Authors: Kundu, M. R.; Gopalswamy, N.
1989BAAS...21R.857K    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Radioheliograph and White-Light Coronagraph Studies of a
    Coronal Mass Ejection Event
Authors: Gopalswamy, N.; Kundu, M. R.
1989SoPh..122..145G    Altcode:
  We analyze the radioheliograph and SMM-C/P observations of 1986 November
  3 mass ejection event. The metric radio emissions are the only detected
  activity associated with the mass ejection, but are adequate to study
  the evolution of the event. The start time of the ejection seems to
  precede a possible flare behind the limb indicated by the early type
  III bursts. We discuss the physical relation between various types of
  bursts and the CME. We interpret moving type IV bursts as a plasma
  emission process. It is also shown using white-light coronagraph
  data that the density in the source region of the moving type IV is
  sufficient to support second harmonic plasma emission at the observed
  frequency of 50 MHz.

---------------------------------------------------------
Title: Interpretation of Multiwavelength Observations of Solar Active
    Regions Obtained During CoMStOC
Authors: Brosius, J. W.; Holman, G. D.; Nitta, N.; White, S. M.; Kundu,
   M. R.; Gopalswamy, N.; Schmelz, J. T.; Saba, J. R. L.; Willson, R.
1989BAAS...21..838B    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Radio and Optical Observations of Moving Magnetic Structures
    in the Solar Corona
Authors: Gopalswamy, N.; Kundu, M. R.
1989BAAS...21..857G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Simultaneous Microwave and Soft X-ray Observations of Active
    Regions at the Solar Limb
Authors: Nitta, N.; White, S.; Kundu, M.; Gopalswamy, N.; Holman,
   G.; Brosius, J.; Schmelz, J.; Saba, J.; Strong, K.
1989BAAS...21..828N    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: The Sun at the VLA's Meter and Decimeter Wavelengths
Authors: White, S. M.; Gopalswamy, N.; Kundu, M. R.
1989BAAS...21..861W    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: A Slowly Moving Plasmoid Associated with a Filament Eruption
Authors: Gopalswamy, N.; Kundu, M. R.
1989SoPh..122...91G    Altcode:
  We report the imaging observations of a slowly moving type IV burst
  associated with a filament eruption. This event was preceded by weak
  type III burst activity and was accompanied by a quasi-stationary
  continuum that persisted for several hours. The starting times and
  speeds of moving type IV burst and the erupting filament are nearly
  the same, implying a close physical relation between the two. The
  moving type IV burst is interpreted as gyrosynchrotron emission from
  a plasmoid containing a magnetic field of ∼1-2 G and nonthermal
  electrons of density ∼10<SUP>5</SUP>-10<SUP>6</SUP> cm<SUP>−3</SUP>
  with a relatively low average energy of ∼50 keV.

---------------------------------------------------------
Title: Recent results of meter-decameter wave observations of
    solar flares.
Authors: Gopalswamy, N.; Kundu, M. R.
1989sasf.confP.185G    Altcode: 1989IAUCo.104P.185G; 1988sasf.conf..185G
  The authors present recent results from meter-decameter imaging of
  several classes of solar radio bursts: preflare activity in the form
  of type III bursts, correlated type IIIs from distant sources, and
  type II and moving type IV bursts associated with flares and CMEs.

---------------------------------------------------------
Title: Three dimensional structures of coronal streamers, holes and
    CME plasmoids from multifrequency imaging observations
Authors: Kundu, M. R.; Schmahl, E. J.; Gopalswamy, N.; White, S. M.
1989AdSpR...9d..41K    Altcode: 1989AdSpR...9R..41K
  Throughout the quiet Sun years 1982-1987, the Clark Lake Radioheliograph
  routinely mapped the solar corona on a daily basis at frequencies from
  30 to 100 MHz. The Clark Lake maps show a variety of features which
  we have analyzed quantitatively, providing information about the three
  dimensional nature of large scale structures of the solar corona.

---------------------------------------------------------
Title: First interferometric observations with arc-sec. resolution
    of solar radio bursts at millimeter wavelengths
Authors: Kundu, Mukul R.; White, S. M.; Gopalswamy, N.; Bieging, J. H.
1989dots.work..119K    Altcode:
  The Berkeley-Maryland-Illinois Array (BIMA) is briefly described in
  the context of solar observations. Specific areas of research that
  could be performed using BIMA during the Solar Maximum Mission (SMM)
  in 1991 are outlined. Some preliminary results of flare observations
  during March 1989 are presented.

---------------------------------------------------------
Title: Millimeter wavelength observations of solar flares for Max 1991
Authors: Kundu, M. R.; Gopalswamy, N.; Nitta, N.; Schmahl, E. J.;
   White, S. M.; Welch, W. J.
1988fnsm.work..107K    Altcode:
  The Hat Creek millimeter-wave interferometer (to be known as the
  Berkeley-Illinois-Maryland Array, BIMA) is being upgraded. The improved
  array will become available during the coming solar maximum, and will
  have guaranteed time for solar observing. The Hat Creek millimeter-wave
  interferometer is described along with the improvements. The scientific
  objectives are briefly discussed.

---------------------------------------------------------
Title: Millimeter Wavelength Observations of Solar Flares for Max'91
Authors: Kundu, M. R.; Gopalswamy, N.; Nitta, N.; Schmahl, E. J.;
   White, S. M.
1988BAAS...20..746K    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Moving Radio Loop Structure During a Fast CME
Authors: Gopalswamy, N.; Kundu, M. R.; Hundhausen, A.
1988BAAS...20Q.682G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Slowly-Varying Observed with the Clark Lake Radioheliograph
Authors: Schmahl, E. J.; Kundu, M. R.; Gopalswamy, N.; Jackson, P. D.
1988BAAS...20..712S    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Imaging observations of the evolution of meter-decameter
    burst emission during a major flare.
Authors: Gopalswamy, N.; Kundu, M. R.
1987SoPh..111..347G    Altcode:
  We present the results of a study of the evolution of 3 February,
  1986 flare at meter-decameter wavelengths using the two dimensional
  imaging observations made with the Clark Lake multifrequency
  radioheliograph. The flare was complex and produced various types
  of meter-decameter bursts. The preflare activity was observed in the
  form of type III bursts some tens of minutes prior to the impulsive
  onset. From the positional analysis of the preflare and impulsive
  phase type III bursts and other measured characteristics we discuss
  the characteristics of energy release and possible magnetic field
  configurations in the vicinity of energy release region. From positional
  and temporal studies of the flare continuum and type II burst in
  relation to the microwave and hard X-ray emissions, we discuss the
  possible magnetic field structures in which the accelerated particles
  are confined or along which they propagate. We develop a schematic
  model of the flaring region based upon our study.

---------------------------------------------------------
Title: A Study of Solar Preflare Activity Using Two-Dimensional
    Radio and Smm/xrp Observations
Authors: Kundu, M. R.; Gopalswamy, N.; Saba, J. L. R.; Schmelz,
   J. T. S.; Strong, K. T.
1987SoPh..114..273K    Altcode:
  We present a study of type III activity at meter- decameter wavelengths
  in the preflare phase of the 1986 February 3 flare using data obtained
  with the Clark Lake Multifrequency Radioheliograph. We compare this
  activity with similar type III burst activity during the impulsive
  phase and find that there is a displacement of burst sources between the
  onset and end times of the activity. A comparison of this displacement
  at three frequencies suggests that the type III emitting electrons gain
  access progressively to diverging and different field lines relative
  to the initial field lines. The energetics of the type III emitting
  electrons are inferred from observations and compared with those of
  the associated hard X-ray emitting electrons. The soft X-ray data from
  SMM-XRP shows enhanced emission measure, density and temperature in
  the region associated with the preflare type III activity.

---------------------------------------------------------
Title: Fine Structures in Solar Microwave Flares
Authors: Gopalswamy, N.
1987SoPh..110..327G    Altcode:
  The pulsed electron acceleration and release from the energy release
  volume in solar flares implies that there is a possibility of
  interaction between a group of electrons reflected from the foot
  of a bipolar flux tube with a newly injected beam. It is shown
  that interaction can lead to the stoppage of the synchrotron maser
  instability caused by the loss cone distribution and hence can produce
  further millisecond fine structures in the solar microwave bursts.

---------------------------------------------------------
Title: Simultaneous radio and white light observations of the 1984
    June 27 coronal mass ejection event
Authors: Gopalswamy, N.; Kundu, M. R.
1987SoPh..114..347G    Altcode:
  We present the two-dimensional imaging observations of radio bursts in
  the frequency range 25-50 MHz made with the Clark Lake multifrequency
  radioheliograph during a coronal mass ejection event (CME) observed
  on 1984, June 27 by the SMM Coronagraph/Polarimeter and Mauna Loa
  K-coronameter. The event was spatially and temporally associated
  with precursors in the form of meter-decameter type III bursts, soft
  X-ray emission and a Hα flare spray. The observed type IV emission
  in association with the CME (and the Hα spray) could be interpreted
  as gyrosynchrotron emission from a plasmoid containing a magnetic
  field of ∼2.5 G and nonthermal electrons with a number density of
  ∼ 10<SUP>5</SUP> cm<SUP>−3</SUP> and energy ≳350 keV.

---------------------------------------------------------
Title: Two dimensional imaging observations of meter-decameter bursts
    associated with the February 1986 flare activity
Authors: Gopalswamy, N.; Kundu, M. R.
1987sici.symp...16G    Altcode:
  An analysis is presented of the two dimensional imaging observations
  of a flare observed on 3 Feb. l986 using the Clark Lake Multifrequency
  Radioheliograph. The flare produced almost all types of Meter-decimeter
  radio emission: enhanced storm radiation, type III/V bursts, II and
  IV and flare continuum. The flare continuum had early (FCE) and late
  (FC II) components and the type II occurred during the period between
  these two components. Comparing the source positions of type III/V and
  FCE it was found that these bursts must have occurred along adjacent
  open and closed field lines, respectively. The positional analysis of
  type II and FC II implies that the nonthermal electrons responsible for
  FC II need not be accelerated by type II shock and this conclusion is
  further supported by the close association of FC II with a microwave
  peak. Using the positional and temporal analysis of all these bursts
  and the associated hard X-ray and microwave emissions, a schematic
  model is developed for the magnetic field configuration in the flaring
  region in which the nonthermal particles responsible for these bursts
  are confined or along which they propagate.

---------------------------------------------------------
Title: Propagation of Electrons Emitting Weak Type-Iii Bursts in
    Coronal Streamers
Authors: Gopalswamy, N.; Kundu, M. R.; Szabo, A.
1987SoPh..108..333G    Altcode:
  We report the observations of weak type III bursts at 73.8, 57.5, 50.0,
  and 38.5 MHz from Clark Lake Radio Observatory on four days and discuss
  their characteristics. In addition to Clark Lake data, the magnetogram
  and sunspot/active region data and the coronal streamer data obtained
  by HAO's Coronagraph/Polarimeter aboard SMM satellite are used to
  study the location of the burst sources with respect to the coronal
  streamers emanating from active regions. It is shown that the bursts
  occur within or close to the edge of dense coronal streamers implying
  that the coronal streamers contain open magnetic field lines along
  which the electrons generating the bursts propagate. The positional
  analysis of the bursts is used to estimate the variation of coronal
  electron density with radial distance.

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Title: Correlated Type-Iii Burst Emission from Distant Sources on
    the Sun
Authors: Kundu, M. R.; Gopalswamy, N.
1987SoPh..112..133K    Altcode:
  We report the observation and interpretation of a correlated type III
  burst emitted from distant sources on the Sun. The angular separation
  between the distant sources is as large as 26' or ∼ 10<SUP>6</SUP>
  km. There was an active region ∼ 30° behind the limb, and it is
  believed that the type III burst emission originated from activity
  in this region. The implications of the locations of the correlated
  sources with regard to the geometry of the magnetic structures involved
  in the flare process are discussed.

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Title: Propagation of Weak Type III Burst Electrons in Dense Coronal
    Streamers
Authors: Gopalswamy, N.; Kundu, M. R.; Szabo, A.
1986BAAS...18R.900G    Altcode:
  No abstract at ADS

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Title: Some interesting features in the drift pair phenomena of
    solar decametric radiation
Authors: Thejappa, G.; Gopalswamy, N.; Sastry, C. N.; Aubier, M. G.
1986ESASP.251..121T    Altcode: 1986plas.work..121T
  Observational results on drift pair (DP) chains and vertical DP bursts
  in the decametric solar corona are reported. As the magnetic field in
  this region is predominantly open, a free energy source propagating
  sunward most of the time cannot explain the predominant reverse drift
  pair chains. The appearance of the vertical chains and DPs rules out
  the possibility of an agency moving in the corona causing the observed
  drift. Observations support the idea that the resonance layer in which
  the radiation is generated is different at different instants of time
  so that one gets a slope in the frequency-time plane. If considerable
  fluctuations in macroscopic parameters are assumed, it is possible
  to have drifts of all directions as the drift rate depends upon the
  medium in which the fluctuations occur. It is shown that the magnetic
  field decreases steeply if the density of the medium is not affected
  by the DP activity when the frequency drift is very high.

---------------------------------------------------------
Title: A Theory of Jovian Shadow Bursts
Authors: Gopalswamy, N.
1986EM&P...35...93G    Altcode:
  The shadow events in the dynamic spectra of Jovian decametric emission
  are explained as the result of interaction between electron bunches
  responsible for S and L emissions. The relevant dispersion relation
  is derived for the fast extraordinary mode in the cold magnetospheric
  plasma in the presence of S and L electron bunches. The growth rate
  of the synchrotron maser instability is studied in the presence
  and absence of S-electrons. It is shown that the synchrotron maser
  instability responsible for L-emission can be temporarily quenched
  by the invasion of S-electrons, thereby stopping the L-emission. The
  theory accounts for various observed features of the shadow events.

---------------------------------------------------------
Title: Estimation of Coronal Magnetic Fields Using Type-I Emission
Authors: Gopalswamy, N.; Thejappa, G.; Sastry, Ch. V.; Tlamicha, A.
1986BAICz..37..115G    Altcode:
  The radial dependence of the coronal magnetic field above active
  regions is calculated using Type-I chain data existing in the
  literature. Assuming that Type-I emission is due to shock waves, the
  upstream shock velocity and the density jump across the shock are
  obtained respectively from the drift rate and the bandwidth of the
  Type-I chains. Making use of the shock velocity and the density jump
  in the Rankine-Hugoniot relation, the Alfvén velocity and hence the
  magnetic field in the corona is calculated. The results are compared
  with existing estimates.

---------------------------------------------------------
Title: Notes and News
Authors: Gopalswamy, N.; Krishan, V.; Tarter, Jill C.
1986BASI...14...56G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Type-I solar radio bursts.
Authors: Gopalswamy, N.
1986KodOB...6...77G    Altcode:
  A brief review of the recent work done on Type-I radio emission in the
  Indian Institute of Astrophysics is presented. The most plausible low
  frequency turbulence needed to generate the Type-I bursts is shown to
  be ion-sound turbulence. A method is presented to evaluate the coronal
  magnetic field using Type-I radio emission data.

---------------------------------------------------------
Title: Estimation of coronal magnetic fields using solar type I
    radio emission.
Authors: Gopalswamy, N.; Thejappa, G.; Sastry, C. V.
1985BASI...13...81G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Ion-sound turbulence due to shock gradients in collisionless
    plasmas.
Authors: Gopalswamy, N.; Thejappa, G.
1985Prama..25..575G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Second Indo-US workshop on solar-terrestrial physics.
Authors: Gopalswamy, N.
1984BASI...12..324G    Altcode:
  Report on the second Indo-US workshop on solar-terrestrial physics, held
  1984 January 30 - February 3 at National Physical Laboratory, New Delhi.

---------------------------------------------------------
Title: Notes and News
Authors: Padmanabhan, T.; Kembhavi, A.; Bhaysar, S. P.; Bhattacharya,
   D.; Gopalswamy, N.
1984BASI...12..319P    Altcode:
  Report on the IAGRG XII meeting held at the University of Poona,
  1983 November 9 - 12.

---------------------------------------------------------
Title: Narrow-band, short duration radio bursts at decameter
    wavelengths andtheir interpretation.
Authors: Gopalswamy, N.; Thejappa, G.; Subramanian, K. R.; Sastry,
   C. V.
1984BASI...12...75G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: An interpretation of decametric absorption bursts
Authors: Gopalswamy, N.; Thejappa, G.; Sastry, Ch. V.
1984stp..conf..197G    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Observations on the Fine Structures in Solar Decametric
    Radio Emission
Authors: Gopalswamy, N.; Thejappa, G.; Sastry, C. V.
1984KodOB...4...47G    Altcode:
  The solar decametric radio emission consists of a variety of fine
  structures. This reflects the complexity of the corona at this
  level. Two observations viz. absorption bursts and short duration
  narrow band bursts are presented. An interpretation of each of these
  observations is provided.

---------------------------------------------------------
Title: Fine structure in solar decametric radiation
Authors: Thejappa, G.; Sastry, Ch. V.; Gopalswamy, N.
1984ntpp.proc..547T    Altcode:
  Observations and interpretations of some of the fine structure in
  decametric solar radio emission - such as (1) the time structure of
  type III bursts, (2) absorption bursts, and (3) slowly drifting spikes
  - are presented. Physical parameters such as the electron temperature,
  the characteristics of collisionless shocks, and the coronal magnetic
  field - are estimated.

---------------------------------------------------------
Title: Observations and interpretation of solar decametric absorption
    bursts.
Authors: Gopalswamy, N.; Thejappa, G.; Sastry, Ch. V.
1983JApA....4..215G    Altcode:
  The observations of intensity reductions or absorption bursts in
  the solar decametric radio-continuum are reported. The reductions
  are interpreted as the absorption of continuum radiation by a
  shock-generated ion sound turbulence present in the layer above the
  continuum level. The duration of the absorption is attributed to the
  life-time of the ion-sound turbulence while the depth of absorption
  is determined by the level of Langmuir waves generated as a result
  of absorption.

---------------------------------------------------------
Title: Absorption of intense electromagnetic beams in a magnetoplasma.
Authors: Gopalswamy, N.; Krishan, V.
1980Ap&SS..73..179G    Altcode:
  The multiphoton inverse bremsstrahlung absorption of two intense
  electromagnetic beams passing through a magnetized plasma is
  studied. The rate of absorption of electromagnetic energy by
  the electrons is calculated by deriving a kinetic equation for
  the electrons. It is found that the absorption enhances when the
  frequency of one electromagnetic beam is more, and that of the other
  electromagnetic beam is less, than the electron-cyclotron frequency. A
  possible application to extragalactic radio sources is discussed.