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Author name code: temmer
ADS astronomy entries on 2022-09-14
author:"Temmer, Manuela" 

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Title: COSPAR Roadmap update from the ISWAT clusters H1 and 2
Authors: Temmer, Manuela; Richardson, Ian G.; Vourlidas, Angelos; Bisi,
   Mario M.; Scolini, Camilla; Heinemann, Stephan; Paouris, Evangelos
2022cosp...44.3523T    Altcode:
  We present the COSPAR Roadmap update paper from the ISWAT clusters
  H1 and 2. These two clusters are focused on interplanetary space and
  its dynamic features such as stream interaction regions and coronal
  mass ejections, the major drivers of space weather. The interplay
  between these phenomena changes the structure of interplanetary space
  on various temporal and spatial scales and effects the propagation
  behavior of individual events. The limitations of observational data
  and current models lead to large uncertainties in our understanding
  of solar wind structures, making reliablespace weather forecasts
  difficult. The solar wind also becomes more complex as solar activity
  increases. We discuss the current understanding of dynamic changes in
  interplanetary space, indicate the caveats related to data and models,
  and provide recommendations for future studies.

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Title: SODA - Satellite Orbit DecAy near-real time forecast
Authors: Drescher, Lukas; Temmer, Manuela; Mayer-Gürr,
   Torsten; Krauss, Sandro; Kroisz, B. Sofia; Behzadpour, Saniya;
   Süsser-Rechberger, Barbara
2022cosp...44..826D    Altcode:
  Based on the results by Krauss et al. (2018, 2020), we investigate
  the correlation between the interplanetary magnetic field of ICMEs
  and the variation of the neutral density in the thermosphere. Within
  the FFG funded project SWEETS (space weather effects on low Earth
  orbiting satellites) we analyze a large sample of about 300 ICMEs
  (interplanetary coronal mass ejections) from 2002 to 2017 and how they
  relate to the orbit decay of satellites. The density estimates are
  based on accelerometer measurements (CHAMP, GRAACE, GRACE-FO) as well
  as on kinematic orbits of the satellite missions Swarm, TerraSAR-X,
  Tandem-X and Sentinel 1, 3. Thus, our investigations covering altitudes
  between 300 to 800 km. We find that strong magnetic field variations in
  the Bz component trigger geomagnetic storms which lead to an increase
  in the neutral density and subsequently the aerodynamic drag. As
  a result, the satellites at very low altitudes may drop by several
  tens to a hundred of meters during an extreme ICME event. From the
  statistical study we derive an empirical relation between Bz value and
  orbit drop for satellites in a normalized height of 490km. Using that
  relation, we established a tool that enables to detect potential orbit
  drops in near real-time. This forecast/nowcast service, called SODA
  (Satellite Orbit DecAy) is implemented in the ESA Ionospheric Weather
  SSP program/Ionospheric Weather Expert Service Centre (I-ESC).

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Title: Determination of CME orientation and consequences for their
    propagation
Authors: Martinic, Karmen; Vrsnak, Bojan; Veronig, Astrid; Dumbovic,
   Mateja; Temmer, Manuela
2022cosp...44.2441M    Altcode:
  The configuration of the interplanetary magnetic field and features
  of the related ambient solar wind in the ecliptic and meridional
  plane are different. Therefore, one can expect that the orientation
  of the flux rope axis of a coronal mass ejection (CME) influences
  the propagation of the CME itself. However, the determination of the
  CME's orientation remains a challenging task to perform. This study
  aims to provide a reference to different CME orientation determination
  methods in the near-Sun environment. Also, it aims to investigate the
  non-radial flow in the sheath region of the interplanetary CME (ICME)
  in order to provide the first proxy to relate the ICME orientation
  with its propagation. We investigated 22 isolated CME-ICME events
  in the period 2008-2015. We first determined the CME orientation in
  the near-Sun environment using a 3D reconstruction of the CME with
  the graduated cylindrical shell (GCS) model applied to coronagraphic
  images provided by the STEREO and SOHO missions. The CME orientation
  in the near-Sun environment was determined using an ellipse fitting
  technique to the CME outer front as determined from the SOHO/LASCO
  coronagraph. In the near-Earth environment, we obtained the orientation
  of the corresponding ICME using in-situ plasma and field data and also
  investigated the non-radial flow in its sheath region. The ability of
  GCS and ellipse fitting to determine the CME orientation is found to be
  limited to reliably distinguish only between the high or low inclination
  of the events. Most of the CME-ICME pairs under investigation were
  found to be characterized by a low inclination. The majority of
  CME-ICME pairs have a consistent estimation of tilt from remote and
  in situ data. The observed non-radial flows in the sheath region show
  a greater y-direction to z-direction flow ratio for high-inclination
  events indicating that CME orientation could have an impact to the
  CME propagation.

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Title: Development and evaluation of Drag-Based Ensemble Model (DBEM)
Authors: Čalogović, Jaša; Vrsnak, Bojan; Veronig, Astrid; Dumbovic,
   Mateja; Temmer, Manuela
2022cosp...44.3443C    Altcode:
  The Drag-based Model (DBM) is a well-known 2D analytical model for
  simulating the heliospheric propagation of Coronal Mass Ejections
  (CMEs). Main output is the prediction of the CME arrival time and
  speed at Earth or any other given target in the solar system. Due to a
  very short computational time of DBM (< 0.01s), the probabilistic
  Drag-Based Ensemble Model (DBEM) was developed by making an ensemble
  of n different input parameters to account for possible variability
  (uncertainties) in the input parameters. Using such an approach
  to obtain the distribution and significance of the DBM results,
  the DBEM determines the CME hit chance, most probable arrival times
  and speeds, quantifies the prediction uncertainties and calculates
  the confidence intervals. As an important tool for space weather
  forecasters, the fully operational DBM/DBEM web application is
  integrated as one of the ESA Space Situational Awareness portal services
  (https://swe.ssa.esa.int/current-space-weather). In the last few years,
  DBM/DBEM has been constantly improved with various new features such as
  Graduated Cylindrical Shell (GCS) option for the CME geometry input,
  the CME propagation visualizations as well as a new DBEM version
  employing the variable solar wind speeds. The model development,
  new features and the corresponding model evaluations will be presented.

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Title: How properties of large-scale solar wind structures drive
    magnetosheath jet properties
Authors: Koller, Florian; Temmer, Manuela; Preisser, Luis; Roberts,
   Owen; Weiss, B. Stefan; Plaschke, Ferdinand
2022cosp...44.1611K    Altcode:
  The Earth's magnetosheath consists of turbulent, shocked solar wind
  (SW) plasma. Magnetosheath jets are dynamic pressure enhancements
  which are frequently observed within this region. They travel
  anti-sunward from the bow shock to the Earth's magnetopause and can be
  geoeffective. While several generation mechanisms have been proposed,
  jets are generally linked to processes at the quasi-parallel bow shock
  and the foreshock. Our goal is to analyze, how these jets are related to
  large-scale SW structures, in particular coronal mass ejections (CMEs)
  as well as stream interaction regions (SIRs) and associated high speed
  streams (HSSs). We use jets detected by the THEMIS spacecraft between
  2008 to 2020. The number of detected jets is lower during the passing
  of CMEs. Significantly more jets are observed during SIRs and HSSs. We
  find that jets are unlikely to appear during a mix of low Alfvénic Mach
  numbers and high IMF cone angles, which are SW conditions often found
  during CMEs and their associated sheaths. These conditions may inhibit
  the formation of a well-defined foreshock and therefore affecting the
  jet generation. We analyze whether jets differ during each type of
  large-scale SW structure and discuss the different possible origin
  mechanisms.

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Title: Magnetosheath jets during a CME and SIR passage: A case study.
Authors: Preisser, Luis; Temmer, Manuela; Roberts, Owen; Koller,
   M. Florian; Plaschke, Ferdinand
2022cosp...44.1642P    Altcode:
  Large scale solar wind (SW) structures called Coronal Mass Ejections
  (CMEs) and Stream Interaction Regions (SIRs) travel through
  the interplanetary medium, where they might impact the Earth's
  magnetosphere. Jets are localized structures characterized by an
  enhancement in dynamic pressure observed propagating through the
  Earth's magnetosheath (EMS) transporting mass, momentum and energy
  and being able to reach and perturb the Earth's magnetopause. Although
  jets have been studied since 20 years, how the different SW conditions
  triggered by CMEs and SIRs change the production of jets in the EMS,
  is a topic that is just beginning to be explored. In this case study we
  characterize jets observed by THEMIS during a CME and a SIR passage. We
  find clear differences in number and size between the jets associated
  with the CME regions arriving at the EMS as well as in comparison with
  the characteristics of jets associated with the SIR passage. Comparing
  WIND and THEMIS data we discuss how these differences are linked to
  the SW conditions and with different jet generation mechanisms.

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Title: Understanding our capabilities in observing and modelling
    Coronal Mass Ejections
Authors: Verbeke, Christine; Mays, M. Leila; Riley, Pete; Mierla,
   Marilena; Cremades, Hebe; Dumbovic, Mateja; Temmer, Manuela; Scolini,
   Camilla; Hinterreiter, Jürgen; Paouris, Evangelos; Palmerio, Erika;
   Kay, Christina; Balmaceda, Laura
2022cosp...44.3441V    Altcode:
  Coronal Mass Ejections (CMEs) are large-scale eruptions of plasma and
  magnetic fields from the Sun. They are considered to be the main drivers
  of strong space weather events at Earth and their arrival time and
  associated shocks are one of the key aspects of space weather. Multiple
  models have been developed over the past decades to be able to predict
  the propagation of CMEs in the interplanetary space and their arrival
  time at Earth. Such models require input from observations, which can
  be used to fit the CME to an appropriate structure. The forecasting
  of CME arrival has proven to be exceedingly challenging. One of the
  major setbacks is the uncertainty of the CME observational input. When
  determining input parameters for CME propagation models, it is common
  procedure to derive kinematic parameters from remote-sensing data. The
  resulting parameters can be used as inputs for the CME propagation
  models to obtain an arrival prediction time of the CME f.e. at
  Earth. However, when fitting the CME structure to obtain the needed
  parameters for simulations, different geometric structures and also
  different parts of the CME structure can be fitted. These aspects,
  together with the fact that 3D reconstructions strongly depend on the
  subjectivity and judgement of the scientist performing them, may lead
  to uncertainties in the fitted parameters. Up to now, no large study
  has tried to map these uncertainties and to evaluate how they affect the
  modelling of CMEs. We will discuss these limits in the scope of the CME
  input analysis that is performed by the ISSI Bern team on "Understanding
  Our Capabilities In Observing and Modelling Coronal Mass Ejections".

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Title: Evolution of ICME sheath and leading-edge structure in the
    inner heliosphere
Authors: Temmer, Manuela; Bothmer, Volker
2022cosp...44.1439T    Altcode:
  We investigate a data sample of 40 interplanetary CME (ICME) events
  from Helios 1 and 2 data that cover the distance range 0.3-1au. For
  comparison, we add a sample of 5 ICMEs observed with Parker Solar
  Probe during 2018-2021. From the solar wind plasma and magnetic field
  measurements, we extract the ICME sub-structures sheath, leading-edge,
  and magnetic ejecta. We analyze their characteristic parameters as
  function of distance and present the main findings of this study: a)
  the average starting distance for actual sheath formation appears to
  be located at a distance of about 13 Rs; b) the sheath density becomes
  dominant over the magnetic ejecta density beyond 38 Rs; c) the sheath
  size could be related to the ambient solar wind density and magnetic
  ejecta characteristics; d) a local linear relation between sheath
  density and ambient solar wind speed was found; e) the leading-edge
  does not increase in size over distance and might be an isolated
  structure wedged in between sheath and magnetic ejecta. With Parker
  Solar Probe approaching the Sun as close as 10Rs, we will certainly
  detect more CME events to obtain measurements that might re-affirm
  the presented results. The current findings can be applied to help
  improve CME propagation models.

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Title: Stellar CME search using large datasets: Balmer line
    asymmetries in optical SDSS spectra
Authors: Koller, Florian; Odert, Petra; Leitzinger, Martin; Veronig,
   Astrid; Temmer, Manuela; Beck, Paul G.
2022cosp...44.1386K    Altcode:
  On the Sun, a strong correlation between highly energetic flares
  and coronal mass ejections (CMEs) has been well established. Highly
  energetic flares have also been frequently detected on all late-type
  stars. However, the association with CMEs proved to be difficult in the
  stellar case. Large datasets are a necessity to increase the probability
  of detecting these sparse events. In order to find stellar flares
  and associated CMEs, we used optical spectra provided by the Sloan
  Digital Sky Survey (SDSS) data release 14. The sample consisted of F,
  G, K, and M main-sequence type stars, resulting in available spectra
  for more than 630 000 stars. We made use of the individual spectral
  exposures provided by the SDSS. Flares were detected by searching for
  significant amplitude changes in the Hα and Hβ spectral lines. We
  searched for CMEs by identifying asymmetries in the Balmer lines
  caused by the Dopplereffect, which indicate plasma motions in the line
  of sight. We detected 281 flares on late-type stars (spectral types
  K3 - M9) and calculated their Hα flare energies. Six possible CME
  candidates were identified that show excess flux in Balmer line wings,
  five of which show red wing enhancements. Our mass estimates for the
  CME candidates range from 6×10$ ^{16}$ -‑ 6×10$ ^{18}$g, and the
  highest projected velocities are 300 -‑ 700km s$ ^{‑1}$. Our low
  detection rate of CMEs agrees with previous studies.

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Title: Galactic cosmic rays as signatures of interplanetary transients
Authors: Dumbovic, Mateja; Kühl, Patrick; Heber, Bernd; Vrsnak,
   Bojan; Temmer, Manuela; Kirin, Anamarija; Hörlöck, Malte; Jensen,
   Stefan; Benko, Ilona; Kramaric, Luka
2022cosp...44.1255D    Altcode:
  Coronal mass ejections (CMEs), interplanetary shocks, and corotating
  interaction regions (CIRs) drive heliospheric variability, causing
  various interplanetary as well as planetary disturbances. One of
  their very common in-situ signatures are short-term reductions in
  the galactic cosmic ray (GCR) flux (i.e. Forbush decreases), which
  are measured by ground-based instruments at Earth and Mars, as well
  as various spacecraft throughout the heliosphere (most recently
  by Solar Orbiter). In general, interplanetary magnetic structures
  interact with GCRs producing depressions in the GCR flux. Therefore,
  different types of interplanetary magnetic structures cause different
  types of Forbush decreases, allowing us to distinguish between
  them. We recently developed and employed two different analytical
  models to explain CME-related and CIR-related Forbush decreases,
  using an expansion-diffusion and the convection-diffusion approaches,
  respectively. We used observation-based generic CME and CIR profiles
  as the theoretical background for the models and tested the models on
  various case studies. Moreover, the CME-related Forbush decrease model
  (ForbMod, Dumbovic et al., 2018; 2020) is brought one step further, as
  it also considers the energy dependance of the detector with which the
  measurements are made. ForbMod is tested through model-to-observations
  comparison to analyse to how many CMEs it is applicable and could
  ultimately provide a helpful tool to analyse Forbush decreases. With
  new modelling efforts, as well as observational analysis we are one
  step closer in utilizing GCR measurements to provide information
  on interplanetary transients, especially where other measurements
  (e.g. plasma, magnetic field) are lacking.

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Title: Acceleration and Expansion of a Coronal Mass Ejection in the
High Corona: Role of Magnetic Reconnection
Authors: Zhuang, Bin; Lugaz, Noé; Temmer, Manuela; Gou, Tingyu;
   Al-Haddad, Nada
2022ApJ...933..169Z    Altcode: 2022arXiv220602090Z
  The important role played by magnetic reconnection in the early
  acceleration of coronal mass ejections (CMEs) has been widely
  discussed. However, as CMEs may have expansion speeds comparable to
  their propagation speeds in the corona, it is not clear whether and
  how reconnection contributes to the true acceleration and expansion
  separately. To address this question, we analyze the dynamics of a
  moderately fast CME on 2013 February 27, associated with a continuous
  acceleration of its front into the high corona, even though its speed
  had reached ~700 km s<SUP>-1</SUP>, which is faster than the solar
  wind. The apparent acceleration of the CME is found to be due to its
  expansion in the radial direction. The true acceleration of the CME,
  i.e., the acceleration of its center, is then estimated by taking into
  account the expected deceleration caused by the drag force of the solar
  wind acting on a fast CME. It is found that the true acceleration and
  the radial expansion have similar magnitudes. We find that magnetic
  reconnection occurs after the eruption of the CME and continues during
  its propagation in the high corona, which contributes to its dynamic
  evolution. Comparison between the apparent acceleration related to the
  expansion and the true acceleration that compensates the drag shows
  that, for this case, magnetic reconnection contributes almost equally
  to the expansion and to the acceleration of the CME. The consequences
  of these measurements for the evolution of CMEs as they transit from
  the corona to the heliosphere are discussed.

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Title: Observations of CME source regions/lower-atmospheric
    manifestations
Authors: Temmer, Manuela
2022cosp...44.1357T    Altcode:
  The Sun is an active star that influences the Earth as well as the
  entire solar system. Most dynamic phenomena are observed as coronal
  mass ejections (CMEs). While CMEs frequently occur at the Sun,
  they are obviously less numerous when it comes to stars. Do we miss
  specific observing techniques? This talk will give an overview on
  the diverse manifestations of CME related signatures on the Sun that
  are observed during the CME early evolution phase. Strong and fast
  events can be most clearly related to their source regions that often
  show bright flare emissions as the reconnection process starts which
  drives the CME. In the wake of the eruption, CMEs expand and leave low
  atmospheric footprints, such as disappearing filaments or dark dimming
  regions, and may generate coronal waves. Weak and slow CMEs might not be
  detected by such footprints as they start from higher up in the corona
  (stealth CMEs). In the radio wavelength, typical signatures of type
  II and III bursts can give hint to propagating shocks and the opening
  of magnetic field. The ambient conditions in which the CME erupts,
  such as strong overlying closed magnetic fields, nearby coronal holes
  (open magnetic field) or multiple eruptions (transient open field),
  may alter the ability to generate specific signatures.

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Title: From CME - CH proximity on the Sun to ICME - CIR interaction
at Earth: a case study
Authors: Geyer, Paul; Dumbovic, Mateja; Temmer, Manuela
2022cosp...44.1121G    Altcode:
  The interaction between interplanetary coronal mass ejections (ICMEs)
  and corotating interaction regions (CIRs) leads to a variety of
  changes both in the trajectory and the morphology of the former. This
  means that the solar wind (SW) conditions at Earth's orbit due to
  interacting heliospheric structures may deviate significantly from the
  case of sole ICME or CIR passage. Studying the interaction of these
  large-scale structures in the heliosphere thus provides a basis for a
  more accurate space weather prediction of the associated near-Earth
  effects and enhances the accuracy of CME propagation models. The
  eruption of a flare related CME southwest to the center of the solar
  disk was observed by SDO/AIA on February 4, 2014. A coronal hole (CH)
  east of the disk center is also present at that time. The CME is listed
  by the DONKI database and associated to the in-situ magnetic field and
  plasma signatures detected at L1 3 days later. After the arrival of a
  fast forward shock on February 7, 2014 typical sheath properties are
  observed, followed by a region of low fluctuations, plasma beta and
  temperature - typical ICME signatures. A SW flow angle reversal is
  observed at the beginning of this interval, indicating east-west flow
  deflection normally observed around stream interfaces. The region of
  typical ICME signatures is interrupted by a phase of decreased field
  magnitude simultaneously occurring with the disturbance of the flow
  speed. Finally, at the trailing part of the in-situ event we observe
  the passage of a high-speed stream. The proximity of the coronal source
  regions of ICME and CIR clearly results in their interaction and thus
  morphological changes visible in plasma and magnetic field data. This
  view is also supported by WSA-ENLIL simulations showing the coincident
  arrival and apparent merging of the CIR and ICME at Earth. The
  separation of two intervals of weak magnetic field fluctuations by a
  region of strong fluctuations indicates a fundamental rearrangement of
  the magnetic field associated with the ICME. This is supported by the
  non-bidirectional electron pitch angle data. The complexity of this
  event demonstrates the need to study the interaction of the coronal
  source regions and their respective SW structures in a holistic way.

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Title: Determination of coronal mass ejection orientation and
    consequences for their propagation
Authors: Martinić, K.; Dumbović, M.; Temmer, M.; Veronig, A.;
   Vršnak, B.
2022A&A...661A.155M    Altcode: 2022arXiv220410112M
  Context. The configuration of the interplanetary magnetic field
  and features of the related ambient solar wind in the ecliptic
  and meridional plane are different. Therefore, one can expect that
  the orientation of the flux-rope axis of a coronal mass ejection
  (CME) influences the propagation of the CME itself. However, the
  determination of the CME orientation, especially from image data,
  remains a challenging task to perform. Aim. This study aims to provide
  a reference to different CME orientation determination methods in
  the near-Sun environment. Also, it aims to investigate the non-radial
  flow in the sheath region of the interplanetary CME (ICME) in order
  to provide the first proxy to relate the ICME orientation with its
  propagation. <BR /> Methods: We investigated 22 isolated CME-ICME
  events in the period 2008-2015. We determined the CME orientation in
  the near-Sun environment using the following: (1) a 3D reconstruction
  of the CME with the graduated cylindrical shell (GCS) model applied
  to coronagraphic images provided by the STEREO and SOHO missions;
  and (2) an ellipse fitting applied to single spacecraft data from
  SOHO/LASCO C2 and C3 coronagraphs. In the near-Earth environment,
  we obtained the orientation of the corresponding ICME using in situ
  plasma and field data and also investigated the non-radial flow in
  its sheath region. <BR /> Results: The ability of GCS and ellipse
  fitting to determine the CME orientation is found to be limited to
  reliably distinguish only between the high or low inclination of the
  events. Most of the CME-ICME pairs under investigation were found to
  be characterized by a low inclination. For the majority of CME-ICME
  pairs, we obtain consistent estimations of the tilt from remote and
  in situ data. The observed non-radial flows in the sheath region show
  a greater y direction to z direction flow ratio for high-inclination
  events, indicating that the CME orientation could have an impact on
  the CME propagation.

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Title: Magnetosheath Jet Occurrence Rate in Relation to CMEs and SIRs
Authors: Koller, Florian; Temmer, Manuela; Preisser, Luis; Plaschke,
   Ferdinand; Geyer, Paul; Jian, Lan K.; Roberts, Owen W.; Hietala,
   Heli; LaMoury, Adrian T.
2022JGRA..12730124K    Altcode:
  Magnetosheath jets constitute a significant coupling effect between
  the solar wind (SW) and the magnetosphere of the Earth. In order to
  investigate the effects and forecasting of these jets, we present the
  first-ever statistical study of the jet production during large-scale
  SW structures like coronal mass ejections (CMEs), stream interaction
  regions (SIRs) and high speed streams (HSSs). Magnetosheath data from
  Time History of Events and Macroscale Interactions during Substorms
  (THEMIS) spacecraft between January 2008 and December 2020 serve as
  measurement source for jet detection. Two different jet definitions
  were used to rule out statistical biases induced by our jet detection
  method. For the CME and SIR + HSS lists, we used lists provided by
  literature and expanded on incomplete lists using OMNI data to cover
  the time range of May 1996 to December 2020. We find that the number and
  total time of observed jets decrease when CME-sheaths hit the Earth. The
  number of jets is lower throughout the passing of the CME-magnetic
  ejecta (ME) and recovers quickly afterward. On the other hand, the
  number of jets increases during SIR and HSS phases. We discuss a few
  possibilities to explain these statistical results.

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Title: How the area of solar coronal holes affects the properties
of high-speed solar wind streams near Earth: An analytical model
Authors: Hofmeister, Stefan J.; Asvestari, Eleanna; Guo, Jingnan;
   Heidrich-Meisner, Verena; Heinemann, Stephan G.; Magdalenic, Jasmina;
   Poedts, Stefaan; Samara, Evangelia; Temmer, Manuela; Vennerstrom,
   Susanne; Veronig, Astrid; Vršnak, Bojan; Wimmer-Schweingruber, Robert
2022A&A...659A.190H    Altcode: 2022arXiv220315689H
  Since the 1970s it has been empirically known that the area of
  solar coronal holes affects the properties of high-speed solar wind
  streams (HSSs) at Earth. We derive a simple analytical model for the
  propagation of HSSs from the Sun to Earth and thereby show how the
  area of coronal holes and the size of their boundary regions affect
  the HSS velocity, temperature, and density near Earth. We assume that
  velocity, temperature, and density profiles form across the HSS cross
  section close to the Sun and that these spatial profiles translate
  into corresponding temporal profiles in a given radial direction due
  to the solar rotation. These temporal distributions drive the stream
  interface to the preceding slow solar wind plasma and disperse with
  distance from the Sun. The HSS properties at 1 AU are then given by
  all HSS plasma parcels launched from the Sun that did not run into
  the stream interface at Earth distance. We show that the velocity
  plateau region of HSSs as seen at 1 AU, if apparent, originates from
  the center region of the HSS close to the Sun, whereas the velocity
  tail at 1 AU originates from the trailing boundary region. Small
  HSSs can be described to entirely consist of boundary region plasma,
  which intrinsically results in smaller peak velocities. The peak
  velocity of HSSs at Earth further depends on the longitudinal width
  of the HSS close to the Sun. The shorter the longitudinal width of
  an HSS close to the Sun, the more of its "fastest" HSS plasma parcels
  from the HSS core and trailing boundary region have impinged upon the
  stream interface with the preceding slow solar wind, and the smaller
  is the peak velocity of the HSS at Earth. As the longitudinal width
  is statistically correlated to the area of coronal holes, this also
  explains the well-known empirical relationship between coronal hole
  areas and HSS peak velocities. Further, the temperature and density
  of HSS plasma parcels at Earth depend on their radial expansion from
  the Sun to Earth. The radial expansion is determined by the velocity
  gradient across the HSS boundary region close to the Sun and gives
  the velocity-temperature and density-temperature relationships at
  Earth their specific shape. When considering a large number of HSSs,
  the assumed correlation between the HSS velocities and temperatures
  close to the Sun degrades only slightly up to 1 AU, but the correlation
  between the velocities and densities is strongly disrupted up to 1
  AU due to the radial expansion. Finally, we show how the number of
  particles of the piled-up slow solar wind in the stream interaction
  region depends on the velocities and densities of the HSS and preceding
  slow solar wind plasma.

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Title: Dynamic Time Warping as a Means of Assessing Solar Wind
    Time Series
Authors: Samara, E.; Laperre, B.; Kieokaew, R.; Temmer, M.; Verbeke,
   C.; Rodriguez, L.; Magdalenić, J.; Poedts, S.
2022ApJ...927..187S    Altcode: 2021arXiv210907873S
  Over the last decades, international attempts have been made to
  develop realistic space weather prediction tools aiming to forecast
  the conditions on the Sun and in the interplanetary environment. These
  efforts have led to the development of appropriate metrics to assess the
  performance of those tools. Metrics are necessary to validate models, to
  compare different models, and to monitor the improvements to a certain
  model over time. In this work, we introduce dynamic time warping (DTW)
  as an alternative way of evaluating the performance of models and,
  in particular, of quantifying the differences between observed and
  modeled solar wind time series. We present the advantages and drawbacks
  of this method, as well as its application to Wind observations and
  EUHFORIA predictions at Earth. We show that DTW can warp sequences
  in time, aiming to align them with the minimum cost by using dynamic
  programming. It can be applied for the evaluation of modeled solar wind
  time series in two ways. The first calculates the sequence similarity
  factor, a number that provides a quantification of how good the forecast
  is compared to an ideal and a nonideal prediction scenario. The second
  way quantifies the time and amplitude differences between the points
  that are best matched between the two sequences. As a result, DTW
  can serve as a hybrid metric between continuous measurements (e.g.,
  the correlation coefficient) and point-by-point comparisons. It is
  a promising technique for the assessment of solar wind profiles,
  providing at once the most complete evaluation portrait of a model.

---------------------------------------------------------
Title: Generic profile of a long-lived corotating interaction region
    and associated recurrent Forbush decrease
Authors: Dumbović, M.; Vršnak, B.; Temmer, M.; Heber, B.; Kühl, P.
2022A&A...658A.187D    Altcode: 2022arXiv220109623D
  Context. Corotating interaction regions (CIRs), formed by the
  interaction of slow solar wind and fast streams that originate from
  coronal holes (CHs), produce recurrent Forbush decreases, which are
  short-term depressions in the galactic cosmic ray (GCR) flux. <BR />
  Aims: Our aim is to prepare a reliable set of CIR measurements to be
  used as a textbook for modeling efforts. For that purpose, we observe
  and analyse a long-lived CIR, originating from a single CH, recurring
  in 27 consecutive Carrington rotations 2057-2083 in the time period
  from June 2007-May 2009. <BR /> Methods: We studied the in situ
  measurements of this long-lived CIR as well as the corresponding
  depression in the cosmic ray (CR) count observed by SOHO/EPHIN
  throughout different rotations. We performed a statistical analysis,
  as well as the superposed epoch analysis, using relative values of the
  key parameters: the total magnetic field strength, B, the magnetic
  field fluctuations, dBrms, plasma flow speed, v, plasma density, n,
  plasma temperature, T, and the SOHO/EPHIN F-detector particle count,
  and CR count. <BR /> Results: We find that the mirrored CR count-time
  profile is correlated with that of the flow speed, ranging from moderate
  to strong correlation, depending on the rotation. In addition, we
  find that the CR count dip amplitude is correlated to the peak in the
  magnetic field and flow speed of the CIR. These results are in agreement
  with previous statistical studies. Finally, using the superposed epoch
  analysis, we obtain a generic CIR example, which reflects the in situ
  properties of a typical CIR well. <BR /> Conclusions: Our results are
  better explained based on the combined convection-diffusion approach of
  the CIR-related GCR modulation. Furthermore, qualitatively, our results
  do not differ from those based on different CHs samples. This indicates
  that the change of the physical properties of the recurring CIR from one
  rotation to another is not qualitatively different from the change of
  the physical properties of CIRs originating from different CHs. Finally,
  the obtained generic CIR example, analyzed on the basis of superposed
  epoch analysis, can be used as a reference for testing future models.

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Title: Characteristics and evolution of sheath and leading edge
    structures of interplanetary coronal mass ejections in the inner
    heliosphere based on Helios and Parker Solar Probe observations
Authors: Temmer, Manuela; Bothmer, Volker
2022arXiv220204391T    Altcode:
  Aims: We statistically investigate the plasma and magnetic field
  characteristics of the upstream regions of interplanetary coronal mass
  ejections (ICMEs) and their evolution as function of distance to the Sun
  in the inner heliosphere. We use a sample of 40 well-observed ICMEs from
  Helios 1/2 (0.3-1au) and 5 from Parker Solar Probe (0.32-0.75au). For
  each event we identify four main density structures, namely shock,
  sheath, leading edge (LE), and magnetic ejecta (ME) itself. Methods:
  We derive separately for each structure averaged plasma and magnetic
  field parameter values as well as duration and place the results
  into comparison with the upstream solar wind (SW) to investigate the
  interrelation between the different density structures. Results:
  The sheath structure presumably consists of compressed plasma due
  to the turbulent SW material following the shock. The sheath lies
  ahead of a region of compressed ambient SW, the LE, which is typically
  found directly in front of the magnetic driver and seems to match the
  bright leading edge commonly observed in remote sensing observations of
  CMEs. The sheath becomes denser than the ambient SW at about 0.06au,
  which we interpret as the average starting distance for actual sheath
  formation. Between 0.09-0.28au the sheath structure density starts to
  dominate over the density within the ME. The ME density seems to fall
  below the ambient SW density over 0.45-1.07au. Besides the well-known
  expansion of the ME, the sheath size shows a weak positive correlation
  with distance, while the LE seems not to expand with distance from the
  Sun. We further find a moderate anti-correlation between sheath density
  and local SW plasma speed upstream of the ICME shock. An empirical
  relation is derived connecting the ambient SW speed with sheath and LE
  density that can be used for modeling of ICME evolution. Constraints
  to those results are given.

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Title: Validation scheme for solar coronal models: Constraints from
    multi-perspective observations in EUV and white light
Authors: Wagner, A.; Asvestari, E.; Temmer, M.; Heinemann, S. G.;
   Pomoell, J.
2022A&A...657A.117W    Altcode: 2021arXiv211001893W; 2021arXiv211001893A
  Context. In this paper, we present a validation scheme to investigate
  the quality of coronal magnetic field models, which is based on
  comparisons with observational data from multiple sources. <BR />
  Aims: Many of these coronal models may use a range of initial
  parameters that produce a large number of physically reasonable
  field configurations. However, that does not mean that these
  results are reliable and comply with the observations. With an
  appropriate validation scheme, which is the aim of this work,
  the quality of a coronal model can be assessed. <BR /> Methods:
  The validation scheme was developed with the example of the EUropean
  Heliospheric FORecasting Information Asset (EUHFORIA) coronal model. For
  observational comparison, we used extreme ultraviolet and white-light
  data to detect coronal features on the surface (open magnetic field
  areas) and off-limb (streamer and loop) structures from multiple
  perspectives (Earth view and the Solar Terrestrial Relations Observatory
  - STEREO). The validation scheme can be applied to any coronal model
  that produces magnetic field line topology. <BR /> Results: We show
  its applicability by using the validation scheme on a large set of
  model configurations, which can be efficiently reduced to an ideal
  set of parameters that matches best with observational data. <BR />
  Conclusions: We conclude that by using a combined empirical visual
  classification with a mathematical scheme of topology metrics, a very
  efficient and objective quality assessment for coronal models can
  be performed.

---------------------------------------------------------
Title: On the influence of CMEs and SIRs on the generation of
    magnetosheath jets
Authors: Koller, Florian; Temmer, Manuela; Preisser, Luis; Plaschke,
   Ferdinand; Roberts, Owen
2021AGUFMSH25G..34K    Altcode:
  Magnetosheath jets are dynamic pressure enhancements observed in
  the Earths magnetosheath. They are significant coupling elements
  between the solar wind and the magnetosphere of the Earth. Jets are
  frequently generated at the Earths bow shock and travel downstream
  to the magnetopause, where they can trigger reconnection and initiate
  geomagnetic substorms. It is so far unexplored how these jets relate to
  large scale solar wind structures that are associated to the solar cycle
  and solar activity. To gain insights into these relations, we analyze
  jet generation during the passing of coronal mass ejections (CMEs)
  and stream interaction regions (SIRs). In our statistical analysis,
  we use magnetosheath jets detected by the THEMIS spacecraft between
  2008 to 2020, and identify all overlaps with CME and SIR intervals. We
  report that magnetosheath jets can be generated at all times, but they
  appear much more frequently during SIRs, while the numbers of observed
  jets decrease significantly during CMEs. To explain this statistical
  difference, we inspect how the solar wind conditions related to the
  observed jets differ during CMEs and SIRs.

---------------------------------------------------------
Title: Characteristics of magnetosheath jets during an CME passage.
Authors: Preisser, Luis; Plaschke, Ferdinand; Koller, Florian; Temmer,
   Manuela; Roberts, Owen
2021AGUFMSH25G..32P    Altcode:
  Jets are localized enhancements in the dynamic pressure observed
  downstream of the Earths bow shock which propagate through the Earths
  magnetosheath (EMS) transporting mass, momentum and energy. Coronal
  Mass Ejections (CMEs) are large scale solar wind events traveling
  through the interplanetary medium. As the CME crosses the EMS,
  its structure (upstream side shock/sheath magnetic ejecta) changes
  the magnetosheath environment. How these changes in the EMS region
  produced by the passage of a CME affect the production of jets is a
  topic not yet explored. In this work we characterize jets observed
  by THEMIS spacecraft during such a passage. We find differences in
  number and size between jets located in the CME upstream region and
  those located in the corresponding CME downstream region. Comparing
  WIND and THEMIS A, D, E data we discuss how these differences can be
  associated to different jet generation mechanisms and if they are or
  not related with the transmission of the CME structure into the EMS.

---------------------------------------------------------
Title: The 2019 International Women's Day Event: A Two-step Solar
    Flare with Multiple Eruptive Signatures and Low Earth Impact
Authors: Dumbovic, Mateja; Veronig, Astrid; Podladchikova, Tatiana;
   Thalmann, Julia; Chikunova, Galina; Dissauer, Karin; Magdalenic,
   Jasmina; Temmer, Manuela; Guo, Jingnan; Samara, Evangelia
2021AGUFMSH32A..08D    Altcode:
  We present a detailed analysis of an eruptive event that occurred on
  early 2019 March 8 in active region AR 12734, to which we refer as the
  International Women's day event. The event under study is intriguing in
  several aspects: 1) low-coronal eruptive signatures come in ”pairs” (a
  double-peak flare, two coronal dimmings, and two EUV waves); 2) although
  the event is characterized by a complete chain of eruptive signatures,
  the corresponding coronagraphic signatures are weak; 3) although
  the source region of the eruption is located close to the center of
  the solar disc and the eruption is thus presumably Earth-directed,
  heliospheric signatures are very weak with little Earth-impact. We
  analyze a number of multi-spacecraft and multi-instrument (both
  remote-sensing and in situ) observations, including Soft X-ray,
  (extreme-) ultraviolet (E)UV), radio and white-light emission, as well
  as plasma, magnetic field and particle measurements. We employ 3D NLFF
  modeling to investigate the coronal magnetic field configuration in and
  around the active region, the GCS model to make a 3D reconstruction of
  the CME geometry and the 3D MHD numerical model EUHFORIA to model the
  background state of the heliosphere. Our results indicate two subsequent
  eruptions of two systems of sheared and twisted magnetic fields,
  which merge already in the upper corona and start to evolve further
  out as a single entity. The large-scale magnetic field significantly
  influences both, the early and the interplanetary evolution of the
  structure. During the first eruption the stability of the overlying
  field was disrupted which enabled the second eruption. We find that
  during the propagation in the interplanetary space the large-scale
  magnetic field, i.e. , the location of heliospheric current sheet
  between the AR and the Earth likely influences propagation and the
  evolution of the erupted structure(s).

---------------------------------------------------------
Title: The Dynamic Time Warping Technique as an Alternative Way to
    Evaluate Space Weather Predictions
Authors: Samara, Evangelia; Chane, Emmanuel; Laperre, Brecht; Kieokaew,
   Rungployphan; Temmer, Manuela; Verbeke, Christine; Rodriguez, Luciano;
   Magdalenic, Jasmina; Poedts, Stefaan
2021AGUFMSH55C1860S    Altcode:
  In this work, the Dynamic Time Warping (DTW) technique is presented
  as an alternative method to quantify differences between observed
  and modeled time series in solar wind forecasting. The method was
  initially developed for speech recognition purposes and over the years
  it met great interest by other scientific fields. In the frame of this
  study, we show for the first time how we can apply DTW to assess the
  performance of modeled time series produced by space weather forecasting
  tools. Dynamic Time Warping can quantify how similar two time series
  are by providing a temporal alignment between them, in an optimal
  way, under certain restrictions. We further discuss the benefits and
  limitations of this method compared to other widely used metrics and
  we show examples on how the technique is applied to predicted solar
  wind time series modeled by EUHFORIA.

---------------------------------------------------------
Title: Quantifying Capabilities in Observing Coronal Mass Ejections
Authors: Verbeke, Christine; Mays, M.; Kay, Christina; Mierla,
   Marilena; Riley, Pete; Palmerio, Erika; Dumbovic, Mateja; Scolini,
   Camilla; Temmer, Manuela; Paouris, Evangelos; Hinterreiter, Jurgen;
   Balmaceda, Laura; Cremades, Hebe
2021AGUFMSH55C1854V    Altcode:
  Coronal Mass Ejections (CMEs) are large-scale eruptions of plasma
  and magnetic fields from the Sun. They are considered to be the main
  drivers of strong space weather events at Earth. Multiple models have
  been developed over the past decades to predict the propagation of
  CMEs and their possible arrival time at Earth. Such models require
  input from observations, which can be used to fit the CME to an
  appropriate structure.When determining parameters associated to
  the CME structure, it is common procedure to derive such kinematic
  parameters from remote-sensing data. The resulting parameters can be
  used as input for CME propagation models to obtain an arrival time
  prediction of the CME e.g. at Earth. However, different geometric
  structures and different parts of the CME structure can be fitted,
  and these aspects, together with the fact that most 3D reconstructions
  are performed by a scientist, creating a subjectivity of the fit, may
  lead to uncertainties in the fitted parameters. To our knowledge, so
  far, no large scale study has tried to map these uncertainties and how
  these affect the modelling of arrival time models.As a start for this
  work, we focused on the effect cause by the influence and subjectivty
  of the performing scientist. We have designed a synthetic situation
  where the true geometric parameters are known in order to quantify
  such uncertainties for the first time and discuss the results. We
  explore further work of the associated ISSI team.

---------------------------------------------------------
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: Space weather: the solar perspective
Authors: Temmer, Manuela
2021LRSP...18....4T    Altcode: 2021arXiv210404261T
  The Sun, as an active star, is the driver of energetic phenomena that
  structure interplanetary space and affect planetary atmospheres. The
  effects of Space Weather on Earth and the solar system is of increasing
  importance as human spaceflight is preparing for lunar and Mars
  missions. This review is focusing on the solar perspective of the Space
  Weather relevant phenomena, coronal mass ejections (CMEs), flares,
  solar energetic particles (SEPs), and solar wind stream interaction
  regions (SIR). With the advent of the STEREO mission (launched in
  2006), literally, new perspectives were provided that enabled for the
  first time to study coronal structures and the evolution of activity
  phenomena in three dimensions. New imaging capabilities, covering the
  entire Sun-Earth distance range, allowed to seamlessly connect CMEs
  and their interplanetary counterparts measured in-situ (so called
  ICMEs). This vastly increased our knowledge and understanding of the
  dynamics of interplanetary space due to solar activity and fostered the
  development of Space Weather forecasting models. Moreover, we are facing
  challenging times gathering new data from two extraordinary missions,
  NASA's Parker Solar Probe (launched in 2018) and ESA's Solar Orbiter
  (launched in 2020), that will in the near future provide more detailed
  insight into the solar wind evolution and image CMEs from view points
  never approached before. The current review builds upon the Living
  Reviews article by Schwenn from 2006, updating on the Space Weather
  relevant CME-flare-SEP phenomena from the solar perspective, as observed
  from multiple viewpoints and their concomitant solar surface signatures.

---------------------------------------------------------
Title: HI-based CME Modeling and the Influence of the Drag-force on
    the CME Frontal Shape
Authors: Amerstorfer, Tanja; Hinterreiter, Jurgen; Temmer, Manuela;
   Weiss, Andreas; Bauer, Maike; Moestl, Christian; Barnard, Luke; Reiss,
   Martin; Pomoell, Jens; Amerstorfer, Ute
2021AGUFMSH33A..03A    Altcode:
  Modeling the evolution of coronal mass ejections through the inner
  heliosphere is still just as challenging as imprecise.A small fleet
  of spacecraft is currently operating in an orbit around the Sun and
  offers the possibility to verify model results by comparing them to
  in situ arrivals at different heliocentric distances, longitudes and
  latitudes.However, deformations of a CME front can be very local making
  them hard to model and difficult to verify. These distortions are mainly
  caused by the interaction of CME and ambient solar wind and lead to
  large differences between different propagation models. With the help
  of heliospheric imagers it is possible to constrain the elongation of
  the CME front to a certain degree. Additionally, these observations
  can be utilized to derive information on the CME kinematics, the CME
  mass and the drag-force exerted by the solar wind. We present the
  first HI-based CME model allowing a CME front to react to the ambient
  solar wind in a local manner leading to frontal deformations. Three
  different ambient solar wind models serve as input to the model and
  underline the need of more precise solar wind modeling in order to
  improve CME arrival prediction models.

---------------------------------------------------------
Title: Searching for flares and associated CMEs on cool stars using
    Balmer lines in SDSS spectra
Authors: Koller, Florian; Leitzinger, Martin; Temmer, Manuela; Odert,
   Petra; Beck, Paul; Veronig, Astrid
2021AGUFM.U43B..04K    Altcode:
  Flares and coronal mass ejections (CMEs) shape the environment of stars
  and can severely affect the atmospheres and therefore the habitability
  of exoplanets. In the case of our Sun, we find that highly energetic
  flares and CMEs are strongly correlated. While we find frequent
  and highly energetic flares on all late-type stars, determining
  the association with stellar CMEs proves to be more difficult. To
  further constrain the activity of late-type main-sequence stars, we
  aimed to detect and classify stellar flares and potential stellar CME
  signatures. For that, we used optical spectra provided by the Sloan
  Digital Sky Survey (SDSS) data release 14. The sample was constrained
  to all F, G, K, and M main-sequence type stars, which resulted in
  available spectra for more than 630 000 stars. We made use of the
  individual spectral exposures provided by the SDSS. To automatically
  detect flares, we searched for significant amplitude changes in the
  $H\alpha$ and $H\beta$ spectral lines after a Gaussian profile was fit
  to each line core. We searched for CMEs by identifying asymmetries in
  the Balmer lines caused by the Dopplereffect, which indicate plasma
  motions in the line of sight. We report 281 flares on late-type stars
  (spectral types K3 M9). Six possible CME candidates were identified
  that show excess flux in Balmer line wings. We calculated $H\alpha$
  Flare energies and estimated the masses of the CME candidates. The
  $H\alpha$ flare energies we derived range from $3 \times 10^{28}
  - 2 \times 10^{33}$ erg. We find that the $H\alpha$ flare energy
  increases with earlier types, while the fraction of flaring times
  increases with later types. Our mass estimates for the CME candidates
  range from $6 \times 10^{16} - 6 \times 10^{18}$ g, and the highest
  projected velocities are $\sim 300 - 700$ km s$^{-1}$. We conclude
  that our low detection rate of CMEs agrees with previous studies,
  suggesting that the CME occurrence rate that can be detected with
  optical spectroscopy is low for late-type main-sequence stars.

---------------------------------------------------------
Title: Drag-Based CME Modeling With Heliospheric Images Incorporating
Frontal Deformation: ELEvoHI 2.0
Authors: Hinterreiter, Jürgen; Amerstorfer, Tanja; Temmer, Manuela;
   Reiss, Martin A.; Weiss, Andreas J.; Möstl, Christian; Barnard,
   Luke A.; Pomoell, Jens; Bauer, Maike; Amerstorfer, Ute V.
2021SpWea..1902836H    Altcode: 2021arXiv210808075H
  The evolution and propagation of coronal mass ejections (CMEs) in
  interplanetary space is still not well understood. As a consequence,
  accurate arrival time and arrival speed forecasts are an unsolved
  problem in space weather research. In this study, we present the ELlipse
  Evolution model based on HI observations (ELEvoHI) and introduce a
  deformable front to this model. ELEvoHI relies on heliospheric imagers
  (HI) observations to obtain the kinematics of a CME. With the newly
  developed deformable front, the model is able to react to the ambient
  solar wind conditions during the entire propagation and along the
  whole front of the CME. To get an estimate of the ambient solar wind
  conditions, we make use of three different models: Heliospheric Upwind
  eXtrapolation model (HUX), Heliospheric Upwind eXtrapolation with
  time dependence model (HUXt), and EUropean Heliospheric FORecasting
  Information Asset (EUHFORIA). We test the deformable front on a CME
  first observed in STEREO-A/HI on February 3, 2010 14:49 UT. For this
  case study, the deformable front provides better estimates of the
  arrival time and arrival speed than the original version of ELEvoHI
  using an elliptical front. The new implementation enables us to study
  the parameters influencing the propagation of the CME not only for
  the apex, but for the entire front. The evolution of the CME front,
  especially at the flanks, is highly dependent on the ambient solar
  wind model used. An additional advantage of the new implementation is
  given by the possibility to provide estimates of the CME mass.

---------------------------------------------------------
Title: How to Estimate the Far-Side Open Flux Using STEREO Coronal
    Holes
Authors: Heinemann, Stephan G.; Temmer, Manuela; Hofmeister, Stefan
   J.; Stojakovic, Aleksandar; Gizon, Laurent; Yang, Dan
2021SoPh..296..141H    Altcode: 2021arXiv210902375H
  Global magnetic field models use as input synoptic data, which usually
  show "aging effects" as the longitudinal 360<SUP>∘</SUP> information
  is not obtained simultaneously. Especially during times of increased
  solar activity, the evolution of the magnetic field may yield large
  uncertainties. A significant source of uncertainty is the Sun's magnetic
  field on the side of the Sun invisible to the observer. Various methods
  have been used to complete the picture: synoptic charts, flux-transport
  models, and far side helioseismology. In this study, we present a new
  method to estimate the far-side open flux within coronal holes using
  STEREO EUV observations. First, we correlate the structure of the
  photospheric magnetic field as observed with the Helioseismic and
  Magnetic Imager on board the Solar Dynamics Observatory (HMI/SDO)
  with features in the transition region. From the 304 Å intensity
  distribution, which we found to be specific to coronal holes, we derive
  an empirical estimate for the open flux. Then we use a large sample of
  313 SDO coronal hole observations to verify this relation. Finally,
  we perform a cross-instrument calibration from SDO to STEREO data
  to enable the estimation of the open flux at solar longitudes not
  visible from Earth. We find that the properties of strong unipolar
  magnetic elements in the photosphere, which determine the coronal
  hole's open flux, can be approximated by open fields in the transition
  region. We find that structures below a threshold of 78 % (STEREO)
  or 94 % (SDO) of the solar disk median intensity as seen in 304 Å
  filtergrams are reasonably well correlated with the mean magnetic
  flux density of coronal holes (cc=sp 0.59 ). Using the area covered
  by these structures (A<SUB>OF</SUB>) and the area of the coronal hole
  (A<SUB>CH</SUB>), we model the open magnetic flux of a coronal hole
  as |Φ<SUB>CH</SUB>|=0.25 A<SUB>CH</SUB>exp (0.032 A<SUB>OF</SUB>)
  with an estimated uncertainty of 40 to 60 %.

---------------------------------------------------------
Title: Coronal Hole Detection and Open Magnetic Flux
Authors: Linker, Jon A.; Heinemann, Stephan G.; Temmer, Manuela;
   Owens, Mathew J.; Caplan, Ronald M.; Arge, Charles N.; Asvestari,
   Eleanna; Delouille, Veronique; Downs, Cooper; Hofmeister, Stefan J.;
   Jebaraj, Immanuel C.; Madjarska, Maria S.; Pinto, Rui F.; Pomoell,
   Jens; Samara, Evangelia; Scolini, Camilla; Vršnak, Bojan
2021ApJ...918...21L    Altcode: 2021arXiv210305837L
  Many scientists use coronal hole (CH) detections to infer open
  magnetic flux. Detection techniques differ in the areas that they
  assign as open, and may obtain different values for the open magnetic
  flux. We characterize the uncertainties of these methods, by applying
  six different detection methods to deduce the area and open flux of
  a near-disk center CH observed on 2010 September 19, and applying
  a single method to five different EUV filtergrams for this CH. Open
  flux was calculated using five different magnetic maps. The standard
  deviation (interpreted as the uncertainty) in the open flux estimate
  for this CH ≍ 26%. However, including the variability of different
  magnetic data sources, this uncertainty almost doubles to 45%. We
  use two of the methods to characterize the area and open flux for
  all CHs in this time period. We find that the open flux is greatly
  underestimated compared to values inferred from in situ measurements
  (by 2.2-4 times). We also test our detection techniques on simulated
  emission images from a thermodynamic MHD model of the solar corona. We
  find that the methods overestimate the area and open flux in the
  simulated CH, but the average error in the flux is only about 7%. The
  full-Sun detections on the simulated corona underestimate the model
  open flux, but by factors well below what is needed to account for
  the missing flux in the observations. Under-detection of open flux in
  coronal holes likely contributes to the recognized deficit in solar
  open flux, but is unlikely to resolve it.

---------------------------------------------------------
Title: Modelling a multi-spacecraft coronal mass ejection encounter
    with EUHFORIA
Authors: Asvestari, E.; Pomoell, J.; Kilpua, E.; Good, S.;
   Chatzistergos, T.; Temmer, M.; Palmerio, E.; Poedts, S.; Magdalenic, J.
2021A&A...652A..27A    Altcode: 2021arXiv210511831A
  Context. Coronal mass ejections (CMEs) are a manifestation of the
  Sun's eruptive nature. They can have a great impact on Earth, but also
  on human activity in space and on the ground. Therefore, modelling
  their evolution as they propagate through interplanetary space is
  essential. <BR /> Aims: EUropean Heliospheric FORecasting Information
  Asset (EUHFORIA) is a data-driven, physics-based model, tracing
  the evolution of CMEs through background solar wind conditions. It
  employs a spheromak flux rope, which provides it with the advantage of
  reconstructing the internal magnetic field configuration of CMEs. This
  is something that is not included in the simpler cone CME model used
  so far for space weather forecasting. This work aims at assessing the
  spheromak CME model included in EUHFORIA. <BR /> Methods: We employed
  the spheromak CME model to reconstruct a well observed CME and compare
  model output to in situ observations. We focus on an eruption from 6
  January 2013 that was encountered by two radially aligned spacecraft,
  Venus Express and STEREO-A. We first analysed the observed properties of
  the source of this CME eruption and we extracted the CME properties as
  it lifted off from the Sun. Using this information, we set up EUHFORIA
  runs to model the event. <BR /> Results: The model predicts arrival
  times from half to a full day ahead of the in situ observed ones,
  but within errors established from similar studies. In the modelling
  domain, the CME appears to be propagating primarily southward, which
  is in accordance with white-light images of the CME eruption close
  to the Sun. <BR /> Conclusions: In order to get the observed magnetic
  field topology, we aimed at selecting a spheromak rotation angle for
  which the axis of symmetry of the spheromak is perpendicular to the
  direction of the polarity inversion line (PIL). The modelled magnetic
  field profiles, their amplitude, arrival times, and sheath region length
  are all affected by the choice of radius of the modelled spheromak.

---------------------------------------------------------
Title: Multi-channel coronal hole detection with convolutional
    neural networks
Authors: Jarolim, R.; Veronig, A. M.; Hofmeister, S.; Heinemann,
   S. G.; Temmer, M.; Podladchikova, T.; Dissauer, K.
2021A&A...652A..13J    Altcode: 2021arXiv210414313J
  Context. A precise detection of the coronal hole boundary is of
  primary interest for a better understanding of the physics of coronal
  holes, their role in the solar cycle evolution, and space weather
  forecasting. <BR /> Aims: We develop a reliable, fully automatic
  method for the detection of coronal holes that provides consistent
  full-disk segmentation maps over the full solar cycle and can perform
  in real-time. <BR /> Methods: We use a convolutional neural network
  to identify the boundaries of coronal holes from the seven extreme
  ultraviolet (EUV) channels of the Atmospheric Imaging Assembly (AIA)
  and from the line-of-sight magnetograms provided by the Helioseismic
  and Magnetic Imager (HMI) on board the Solar Dynamics Observatory
  (SDO). For our primary model (Coronal Hole RecOgnition Neural Network
  Over multi-Spectral-data; CHRONNOS) we use a progressively growing
  network approach that allows for efficient training, provides detailed
  segmentation maps, and takes into account relations across the full
  solar disk. <BR /> Results: We provide a thorough evaluation for
  performance, reliability, and consistency by comparing the model
  results to an independent manually curated test set. Our model shows
  good agreement to the manual labels with an intersection-over-union
  (IoU) of 0.63. From the total of 261 coronal holes with an area
  &gt; 1.5 × 10<SUP>10</SUP> km<SUP>2</SUP> identified during
  the time-period from November 2010 to December 2016, 98.1% were
  correctly detected by our model. The evaluation over almost the full
  solar cycle no. 24 shows that our model provides reliable coronal
  hole detections independent of the level of solar activity. From a
  direct comparison over short timescales of days to weeks, we find
  that our model exceeds human performance in terms of consistency
  and reliability. In addition, we train our model to identify coronal
  holes from each channel separately and show that the neural network
  provides the best performance with the combined channel information,
  but that coronal hole segmentation maps can also be obtained from
  line-of-sight magnetograms alone. <BR /> Conclusions: The proposed
  neural network provides a reliable data set for the study of solar-cycle
  dependencies and coronal-hole parameters. Given the fast and robust
  coronal hole segmentation, the algorithm is also highly suitable for
  real-time space weather applications. <P />Movies are available at <A
  href="https://www.aanda.org/10.1051/0004-6361/202140640/olm">https://www.aanda.org</A>

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Title: 2019 International Women's Day event. Two-step solar flare
    with multiple eruptive signatures and low Earth impact
Authors: Dumbović, M.; Veronig, A. M.; Podladchikova, T.; Thalmann,
   J. K.; Chikunova, G.; Dissauer, K.; Magdalenić, J.; Temmer, M.; Guo,
   J.; Samara, E.
2021A&A...652A.159D    Altcode: 2021arXiv210615417D
  Context. We present a detailed analysis of an eruptive event that
  occurred on 2019 March 8 in the active region AR 12734, which we
  refer as the International Women's Day event. The event under study
  is intriguing based on several aspects: (1) low-coronal eruptive
  signatures come in `pairs', namely, there is a double-peaked flare,
  two coronal dimmings, and two extreme ultraviolet (EUV) waves; (2)
  although the event is characterized by a complete chain of eruptive
  signatures, the corresponding coronagraphic signatures are weak;
  and (3) although the source region of the eruption is located close
  to the center of the solar disc and the eruption is thus presumably
  Earth-directed, heliospheric signatures are very weak with very weak
  Earth impact. <BR /> Aims: In order to understand the initiation and
  evolution of this particular event, we performed a comprehensive
  analysis using a combined observational-modeling approach. <BR />
  Methods: We analyzed a number of multi-spacecraft and multi-instrument
  (both remote-sensing and in situ) observations, including soft X-ray,
  EUV, radio and white-light emission, as well as plasma, magnetic field,
  and particle measurements. We employed 3D nonlinear force-free modeling
  to investigate the coronal magnetic field configuration in and around
  the active region, the graduated cylindrical shell model to make a 3D
  reconstruction of the CME geometry, and the 3D magnetohydrodynamical
  numerical model EUropean Heliospheric FORecasting Information Asset
  to model the background state of the heliosphere. <BR /> Results:
  Our results reveal a two-stage C1.3 flare, associated with two
  EUV waves that occur in close succession and two-stage coronal
  dimmings that evolve co-temporally with the flare and type II and
  III radio bursts. Despite its small GOES class, a clear drop in
  magnetic free energy and helicity is observed during the flare. White
  light observations do not unambiguously indicate two separate CMEs,
  but rather a single entity most likely composed of two sheared and
  twisted structures corresponding to the two eruptions observed in the
  low corona. The corresponding interplanetary signatures are that of
  a small flux rope swith indications of strong interactions with the
  ambient plasma, which result in a negligible geomagnetic impact. <BR
  /> Conclusions: Our results indicate two subsequent eruptions of
  two systems of sheared and twisted magnetic fields, which already
  begin to merge in the upper corona and start to evolve further out
  as a single entity. The large-scale magnetic field significantly
  influences both the early and the interplanetary evolution of the
  structure. During the first eruption, the stability of the overlying
  field was disrupted, enabling the second eruption. We find that during
  the propagation in the interplanetary space the large-scale magnetic
  field, that is, the location of heliospheric current sheet between the
  AR and the Earth, is likely to influence propagation, along with the
  evolution of the erupted structure(s). <P />Movies are available at <A
  href="https://www.aanda.org/10.1051/0004-6361/202140752/olm">https://www.aanda.org</A>

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Title: Probabilistic Drag-Based Ensemble Model (DBEM) Evaluation
    for Heliospheric Propagation of CMEs
Authors: Čalogović, Jaša; Dumbović, Mateja; Sudar, Davor; Vršnak,
   Bojan; Martinić, Karmen; Temmer, Manuela; Veronig, Astrid M.
2021SoPh..296..114C    Altcode: 2021arXiv210706684C
  The Drag-based Model (DBM) is a 2D analytical model for heliospheric
  propagation of Coronal Mass Ejections (CMEs) in ecliptic plane
  predicting the CME arrival time and speed at Earth or any other given
  target in the solar system. It is based on the equation of motion and
  depends on initial CME parameters, background solar wind speed, w and
  the drag parameter γ . A very short computational time of DBM (&lt;
  0.01 s) allowed us to develop the Drag-Based Ensemble Model (DBEM)
  that takes into account the variability of model input parameters
  by making an ensemble of n different input parameters to calculate
  the distribution and significance of the DBM results. Thus the DBEM
  is able to calculate the most likely CME arrival times and speeds,
  quantify the prediction uncertainties and determine the confidence
  intervals. A new DBEMv3 version is described in detail and evaluated
  for the first time determining the DBEMv3 performance and errors by
  using various CME-ICME lists and it is compared with previous DBEM
  versions, ICME being a short-hand for interplanetary CME. The analysis
  to find the optimal drag parameter γ and ambient solar wind speed
  w showed that somewhat higher values (γ ≈0.3 ×10<SUP>−7</SUP>
  km<SUP>−1</SUP>, w ≈ 425 km s<SUP>−1</SUP>) for both of these DBEM
  input parameters should be used for the evaluation than the previously
  employed ones. Based on the evaluation performed for 146 CME-ICME pairs,
  the DBEMv3 performance with mean error (ME) of −11.3 h, mean absolute
  error (MAE) of 17.3 h was obtained. There is a clear bias towards
  the negative prediction errors where the fast CMEs are predicted to
  arrive too early, probably due to the model physical limitations and
  input errors (e.g. CME launch speed). This can be partially reduced by
  using larger values for γ resulting in smaller prediction errors (ME
  =−3.9 h, MAE = 14.5 h) but at the cost of larger prediction errors
  for single fast CMEs as well as larger CME arrival speed prediction
  errors. DBEMv3 showed also slight improvement in the performance for
  all calculated output parameters compared to the previous DBEM versions.

---------------------------------------------------------
Title: Drag-based model (DBM) tools for forecast of coronal mass
    ejection arrival time and speed
Authors: Dumbović, Mateja; Čalogović, Jaša; Martinić, Karmen;
   Vršnak, Bojan; Sudar, Davor; Temmer, Manuela; Veronig, Astrid
2021FrASS...8...58D    Altcode: 2021arXiv210314292D
  Forecasting the arrival time of coronal mass ejections (CMEs) and
  their associated shocks is one of the key aspects of space weather
  research and predictions. One of the commonly used models is, due
  to its simplicity and calculation speed, the analytical drag-based
  model (DBM) for heliospheric propagation of CMEs. DBM relies on
  the observational fact that slow CMEs accelerate whereas fast CMEs
  decelerate, and is based on the concept of MHD drag, which acts to
  adjust the CME speed to the ambient solar wind. Although physically
  DBM is applicable only to the CME magnetic structure, it is often used
  as a proxy for the shock arrival. In recent years, the DBM equation
  has been used in many studies to describe the propagation of CMEs
  and shocks with different geometries and assumptions. Here we give
  an overview of the five DBM versions currently available and their
  respective tools, developed at Hvar Observatory and frequently used
  by researchers and forecasters. These include: 1) basic 1D DBM, a 1D
  model describing the propagation of a single point (i.e. the apex of
  the CME) or concentric arc (where all points propagate identically); 2)
  advanced 2D self-similar cone DBM, a 2D model which combines basic DBM
  and cone geometry describing the propagation of the CME leading edge
  which evolves self-similarly; 3) 2D flattening cone DBM, a 2D model
  which combines basic DBM and cone geometry describing the propagation
  of the CME leading edge which does not evolve self-similarly; 4)
  DBEMv1, an ensemble version of the 2D flattening cone DBM which uses
  CME ensembles as an input and 5) DBEMv3, an ensemble version of the
  2D flattening cone DBM which creates CME ensembles based on the input
  uncertainties. All five versions have been tested and published in
  recent years and are available online or upon request. We provide an
  overview of these five tools, of their similarities and differences,
  as well as discuss and demonstrate their application.

---------------------------------------------------------
Title: Properties of stream interaction regions at Earth and Mars
    during the declining phase of SC 24
Authors: Geyer, Paul; Temmer, Manuela; Guo, Jingnan; Heinemann,
   Stephan G.
2021A&A...649A..80G    Altcode: 2021arXiv210205948G
  <BR /> Aims: We inspect the evolution of stream interaction regions
  (SIRs) from Earth to Mars, covering the distance range 1-1.5 AU, over
  the declining phase of solar cycle 24 (2014-2018). So far, studies
  only analyzed SIRs measured at Earth and Mars at different times. We
  compare existing catalogs for both heliospheric distances and arrive at
  a clean dataset for the identical time range. This allows a well-sampled
  statistical analysis and for the opposition phases of the planets an
  in-depth analysis of SIRs as they evolve with distance. <BR /> Methods:
  We use in situ solar wind data from OMNI and the Mars Atmosphere and
  Volatile EvolutioN spacecraft as well as remote sensing data from Solar
  Dynamics Observatory. A superposed epoch analysis is performed for bulk
  speed, proton density, temperature, magnetic field magnitude and total
  perpendicular pressure. Additionally, a study of events during the
  two opposition phases of Earth and Mars in the years 2016 and 2018 is
  conducted. SIR related coronal holes with their area as well as their
  latitudinal and longitudinal extent are extracted and correlated to
  the maximum bulk speed and duration of the corresponding high speed
  solar wind streams following the stream interaction regions. <BR />
  Results: We find that while the entire solar wind high speed stream
  shows no expansion as it evolves from Earth to Mars, the crest of
  the high speed stream profile broadens by about 17%, and the magnetic
  field and total pressure by about 45% around the stream interface. The
  difference between the maximum and minimum values in the normalized
  superposed profiles increases slightly or stagnates from 1-1.5 AU
  for all parameters, except for the temperature. A sharp drop at zero
  epoch time is observed in the superposed profiles for the magnetic
  field strength at both heliospheric distances. The two opposition
  phases reveal similar correlations of in situ data with coronal hole
  parameters for both planets. Maximum solar wind speed has a stronger
  dependence on the latitudinal extent of the respective coronal hole
  than on its longitudinal extent. We arrive at an occurrence rate of
  fast forward shocks three times higher at Mars than at Earth.

---------------------------------------------------------
Title: Current status of project SWEETS: Estimating thermospheric
    neutral mass densities from satellite data at various altitudes
Authors: Krauss, Sandro; Suesser-Rechberger, Barbara; Behzadpour,
   Saniya; Mayer-Guerr, Torsten; Temmer, Manuela; Kroisz, Sofia;
   Drescher, Lukas
2021EGUGA..23.4174K    Altcode:
  Within the project SWEETS (funded by the FFG Austria) it is intended
  to develop a forecasting model, to predict the expected impact of solar
  events, like coronal mass ejections (CMEs), on satellites at different
  altitudes between 300-800 km. For the realization, scientific data,
  such as kinematic orbit information and accelerometer measurements, from
  a wide variety of satellites are incorporated. Based on the evaluation
  of the impact of several hundred solar events on the thermosphere the
  forecasting will be realized through a joint analysis and evaluation
  of solar wind plasma and magnetic field data observed at the Lagrange
  point L1.In this contribution we show first preliminary results of
  thermospheric densities estimates based on kinematic orbit information
  for different satellite missions (e.g., TerraSAR-X, TanDEM-X, Swarm A-C,
  GRACE, GRACE-FO, CHAMP). To validate the outcome, we compare the results
  with state-of-the-art thermospheric models as well as with densities
  estimated from accelerometer measurements if available. Finally,
  for some specific CME events we will perform a comparison between
  the post-processed density estimates and results from our preliminary
  forecasting tool.

---------------------------------------------------------
Title: Statistical study of CMEs, lateral overexpansion and SEP events
Authors: Adamis, Alexandros; Veronig, Astrid; Podladchikova, Tatiana;
   Dissauer, Karin; Miteva, Rositsa; Guo, Jingnan; Haberle, Veronika;
   Dumbovic, Mateja; Temmer, Manuela; Kozarev, Kamen; Magdalenic, Jasmina;
   Kay, Christina
2021EGUGA..23.3216A    Altcode:
  We present a statistical study on the early evolution of coronal mass
  ejections (CMEs), to better understand the effect of CME (over)-
  expansion and how it relates to the production of Solar Energetic
  Particle (SEP) events. We study the kinematic CME characteristics
  in terms of their radial and lateral expansion, from their early
  evolution in the Sun"s atmosphere as observed in EUV imagers and
  coronagraphs. The data covers 72 CMEs that occurred in the time range of
  July 2010 to September 2012, where the twin STEREO spacecraft where in
  quasiquadrature to the Sun-Earth line. From the STEREO point-of-view,
  the CMEs under study were observed close to the limb. We calculated
  the radial and lateral height (width) versus time profiles and
  derived the corresponding peak and mean velocities, accelerations,
  and angular expansion rates, with particular emphasis on the role
  of potential lateral overexpansion in the early CME evolution. We
  find high correlations between the radial and lateral CME velocities
  and accelerations. CMEs that are associated tend to be located at
  the high-value end of the distributions of velocities, widths, and
  expansion rates compared to nonSEP associated events.

---------------------------------------------------------
Title: Statistical relations between in-situ measured Bz component
    and thermospheric density variations
Authors: Kroisz, Sofia; Drescher, Lukas; Temmer, Manuela; Krauss,
   Sandro; Süsser-Rechberger, Barbara; Mayer-Gürr, Torsten
2021EGUGA..23.4773K    Altcode:
  Through advanced statistical investigation and evaluation of solar
  wind plasma and magnetic field data, we investigate the statistical
  relation between the magnetic field Bz component, measured at L1,
  and Earth"s thermospheric neutral density. We will present preliminary
  results of the time series analyzes using in-situ plasma and magnetic
  field measurements from different spacecraft in near Earth space (e.g.,
  ACE, Wind, DSCOVR) and relate those to derived thermospheric densities
  from various satellites (e.g., GRACE, CHAMP). The long and short term
  variations and dependencies in the solar wind data are related to
  variations in the neutral density of the thermosphere and geomagnetic
  indices. Special focus is put on the specific signatures that stem from
  coronal mass ejections and stream or corotating interaction regions. The
  results are used to develop a novel short-term forecasting model called
  SODA (Satellite Orbit DecAy). This is a joint study between TU Graz
  and University of Graz funded by the FFG Austria (project "SWEETS").

---------------------------------------------------------
Title: Multi-Channel Coronal Hole Detection with Convolutional
    Neural Networks
Authors: Jarolim, Robert; Veronig, Astrid; Hofmeister, Stefan;
   Heinemann, Stephan; Temmer, Manuela; Podladchikova, Tatiana; Dissauer,
   Karin
2021EGUGA..23.1490J    Altcode:
  Being the source region of fast solar wind streams, coronal holes are
  one of the key components which impact space weather. The precise
  detection of the coronal hole boundary is an important criterion
  for forecasting and solar wind modeling, but also challenges our
  current understanding of the magnetic structure of the Sun. We use
  deep-learning to provide new methods for the detection of coronal holes,
  based on the multi-band EUV filtergrams and LOS magnetogram from the
  AIA and HMI instruments onboard the Solar Dynamics Observatory. The
  proposed neural network is capable to simultaneously identify full-disk
  correlations as well as small-scale structures and efficiently combines
  the multi-channel information into a single detection. From the
  comparison with an independent manually curated test set, the model
  provides a more stable extraction of coronal holes than the samples
  considered for training. Our method operates in real-time and provides
  reliable coronal hole extractions throughout the solar cycle, without
  any additional adjustments. We further investigate the importance of
  the individual channels and show that our neural network can identify
  coronal holes solely from magnetic field data.

---------------------------------------------------------
Title: Comparative study of halo CME arrival predictions
Authors: Yordanova, Emiliya; Dumbovic, Mateja; Temmer, Manuela;
   Scolini, Camilla; Magdalenic, Jasmina; Thompson, William J.;
   Sorriso-Valvo, Luca; Dimmock, Andrew P.; Rosenqvist, Lisa
2021EGUGA..2314187Y    Altcode:
  Halo coronal mass ejections (CMEs) are one of the most effective
  drivers of intense geomagnetic storms. Despite the recent advances
  in space weather forecasting, the accurate arrival prediction of
  halo CMEs remains a challenge. This is because in general CMEs
  interact with the background solar wind during their propagation in
  the interplanetary space. In addition, in the case of halo CMEs,
  the accurate estimation of their kinematics is difficult due
  to projection effects in the plane-of-sky.In this study, we are
  revisiting the arrival of twelve geoeffective Earth-directed fast
  halo CMEs using an empirical and a numerical approaches. For this
  purpose we refine the input to the Drag-based Model (DBM) and to
  the EUropean Heliospheric Forecasting Information Asset (EUHFORIA),
  which are recently available for users from the ESA Space Situational
  Awareness Portal (http://swe.ssa.esa.int).The DBM model has been tested
  using different values for the input drag parameter. On average, the
  predicted arrival times are confined in the range of ± 10 h. The
  closest arrival to the observed one has been achieved with a drag
  value higher than the recommended for fast CMEs. Setting a higher
  drag also helped to obtain a closer to the observed CME arrival
  speed prediction. These results suggest that the exerted solar wind
  drag was higher than expected. Further, we are searching for clues
  about the CME propagation by performing EUHFORIA runs using the same
  CME kinematics. Preliminary results show that both models perform
  poorly for CMEs that have possibly undergone CME-CME interaction,
  underlying again the importance of taking into account the state of
  the interplanetary space in the CME forecast.

---------------------------------------------------------
Title: Deriving CME volume and density from remote sensing data
Authors: Temmer, Manuela; Holzknecht, Lukas; Dumbovic, Mateja;
   Vrsnak, Bojan; Sachdeva, Nishtha; Heinemann, Stephan G.; Dissauer,
   Karin; Scolini, Camilla; Asvestari, Eleanna; Veronig, Astrid M.;
   Hofmeister, Stefan
2021EGUGA..23.2535T    Altcode:
  Using combined STEREO-SOHO white-light data, we present a method to
  determine the volume and density of a coronal mass ejection (CME) by
  applying the graduated cylindrical shell model (GCS) and deprojected
  mass derivation. Under the assumption that the CME mass is roughly
  equally distributed within a specific volume, we expand the CME
  self-similarly and calculate the CME density for distances close to the
  Sun (15-30 Rs) and at 1 AU. The procedure is applied on a sample of 29
  well-observed CMEs and compared to their interplanetary counterparts
  (ICMEs). Specific trends are derived comparing calculated and in-situ
  measured proton densities at 1 AU, though large uncertainties are
  revealed due to the unknown mass and geometry evolution: i) a moderate
  correlation for the magnetic structure having a mass that stays
  rather constant and ii) a weak correlation for the sheath density by
  assuming the sheath region is an extra mass - as expected for a mass
  pile-up process - that is in its amount comparable to the initial
  CME deprojected mass. High correlations are derived between in-situ
  measured sheath density and the solar wind density and solar wind speed
  as measured 24 hours ahead of the arrival of the disturbance. This
  gives additional confirmation that the sheath-plasma indeed stems from
  piled-up solar wind material. While the CME interplanetary propagation
  speed is not related to the sheath density, the size of the CME may
  play some role in how much material is piled up.

---------------------------------------------------------
Title: Constraining the CME parameters of the spheromak flux rope
    implemented in EUHFORIA
Authors: Asvestari, Eleanna; Pomoell, Jens; Kilpua, Emilia; Good,
   Simon; Chatzistergos, Theodosios; Temmer, Manuela; Palmerio, Erika;
   Poedts, Stefaan; Magdalenic, Jasmina
2021EGUGA..23.3291A    Altcode:
  Coronal mass ejections (CMEs) are primary drivers of space weather
  phenomena. Modelling the evolution of the internal magnetic field
  configuration of CMEs as they propagate through the interplanetary
  space is an essential part of space weather forecasting. EUHFORIA
  (EUropean Heliospheric FORecasting Information Asset) is a data-driven,
  physics-based model, able to trace the evolution of CMEs and CME-driven
  shocks through realistic background solar wind conditions. It employs
  a spheromak-type magnetic flux rope that is initially force-free,
  providing it with the advantage of modelling CME as magnetised
  structures. For this work we assessed the spheromak CME model
  employed in EUHFORIA with a test CME case study. The selected CME
  eruption occurred on the 6th of January 2013 and was encountered
  by two spacecraft, Venus Express and STEREO--A, which were radially
  aligned at the time of the CME passage. Our focus was to constrain
  the input parameters, with particular interest in: (1) translating
  the angular widths of the graduated cylindrical shell (GCS) fitting
  to the spheromak radius, and (2) matching the observed magnetic field
  topology at the source region. We ran EUHFORIA with three different
  spheromak radii. The model predicts arrival times from half to a full
  day ahead of the one observed in situ. We conclude that the choice
  of spheromak radius affected the modelled magnetic field profiles,
  their amplitude, arrival times, and sheath region length.

---------------------------------------------------------
Title: CME arrival time predictions with a deformable front
Authors: Hinterreiter, Jürgen; Amerstorfer, Tanja; Reiss, Martin A.;
   Weiss, Andreas J.; Möstl, Christian; Temmer, Manuela; Bauer, Maike;
   Bailey, Rachel L.; Amerstorfer, Ute V.
2021EGUGA..23.5830H    Altcode:
  We present the first results of our newly developed CME arrival
  prediction model, which allows the CME front to deform and adapt to
  the changing solar wind conditions. Our model is based on ELEvoHI
  and makes use of the WSA/HUX (Wang-Sheeley-Arge/Heliospheric Upwind
  eXtrapolation) model combination, which computes large-scale ambient
  solar wind conditions in the interplanetary space. With an estimate of
  the solar wind speed and density, we are able to account for the drag
  exerted on different parts of the CME front. Initially, our model relies
  on heliospheric imager observations to confine an elliptical CME front
  and to obtain an initial speed and drag parameter for the CME. After
  a certain distance, each point of the CME front is propagating based
  on the conditions in the heliosphere. In this case study, we compare
  our results to previous arrival time predictions using ELEvoHI with
  a rigid CME front. We find that the actual arrival time at Earth and
  the arrival time predicted by the new model are in very good agreement.

---------------------------------------------------------
Title: Evolution of stream interaction regions from 1 to 1.5 AU
Authors: Geyer, Paul; Temmer, Manuela; Guo, Jingnan; Heinemann, Stephan
2021EGUGA..2312513G    Altcode:
  We inspect the evolution of stream interaction regions from Earth to
  Mars for the declining solar cycle 24. In particular, the opposition
  phases of the two planets are analyzed in more detail. So far, there
  is no study comparing the long-term properties of stream interaction
  regions and accompanying high-speed streams at both planets for the
  same time period. We build a catalogue covering a dataset of all
  measured stream interaction regions at Earth and Mars for the time
  period December 2014 - November 2018. The number of events (&gt;120)
  allows for a strong statistical basis. To build the catalogue we use
  near-earth OMNI data as well as measurements from the Mars Atmosphere
  and Volatile EvolutioN (MAVEN) spacecraft. For the opposition phase,
  we additionally use image data from the Solar Dynamics Observatory
  to complement the in-situ observations. Bulk speed, proton density,
  temperature, magnetic field magnitude and total perpendicular pressure
  are statistically evaluated using a superposed epoch analysis. For
  the opposition phase, coronal holes that are linked to individual
  streams are identified. The extracted coronal hole areas (using CATCH)
  and their longitudinal/latitudinal extension are correlated to the
  duration and maximum bulk speed of the high-speed stream following
  the passage of a stream interaction region. We find that an expansion
  of the stream interface from 1 to 1.5 AU is most visible in magnetic
  field and total perpendicular pressure. The duration of the high-speed
  stream does not increase significantly from Earth to Mars, however,
  the stream crest seems to increase. The amplitudes of the SW parameters
  are found to only slightly increase or stagnate from 1 - 1.5 AU. We
  arrive at similar correlation coefficients for both planets with the
  properties of the related coronal holes. There is a stronger linking
  of maximum bulk speed to latitudinal extent of the coronal hole than
  to the longitudinal. On average, the occurrence rate of fast forward
  shocks increases from Earth to Mars.

---------------------------------------------------------
Title: Why are ELEvoHI CME Arrival Predictions Different if Based
    on STEREO A or STEREO B Heliospheric Imager Observations?
Authors: Hinterreiter, Jürgen; Amerstorfer, Tanja; Reiss, Martin
   A.; Möstl, Christian; Temmer, Manuela; Bauer, Maike; Amerstorfer,
   Ute V.; Bailey, Rachel L.; Weiss, Andreas J.; Davies, Jackie A.;
   Barnard, Luke A.; Owens, Mathew J.
2021SpWea..1902674H    Altcode: 2021arXiv210207478H
  Accurate forecasting of the arrival time and arrival speed of
  coronal mass ejections (CMEs) is an unsolved problem in space weather
  research. In this study, a comparison of the predicted arrival times
  and speeds for each CME based, independently, on the inputs from the
  two STEREO vantage points is carried out. We perform hindcasts using
  ELlipse Evolution model based on Heliospheric Imager observations
  (ELEvoHI) ensemble modeling. An estimate of the ambient solar wind
  conditions is obtained by the Wang Sheeley Arge/Heliospheric Upwind
  eXtrapolation (WSA/HUX) model combination that serves as input to
  ELEvoHI. We carefully select 12 CMEs between February 2010 and July
  2012 that show clear signatures in both STEREO A and STEREO B HI time
  elongation maps, that propagate close to the ecliptic plane, and that
  have corresponding in situ signatures at Earth. We find a mean arrival
  time difference of 6.5 h between predictions from the two different
  viewpoints, which can reach up to 9.5 h for individual CMEs, while the
  mean arrival speed difference is 63 km s<SUP>−1</SUP>. An ambient
  solar wind with a large speed variance leads to larger differences
  in the STEREO A and STEREO B CME arrival time predictions (cc =
  0.92). Additionally, we compare the predicted arrivals, from both
  spacecraft, to the actual in situ arrivals at Earth and find a mean
  absolute error of 7.5 ± 9.5 h for the arrival time and 87 ± 111 km
  s<SUP>−1</SUP> for the arrival speed. There is no tendency for one
  spacecraft to provide more accurate arrival predictions than the other.

---------------------------------------------------------
Title: Search for flares and associated CMEs on late-type
    main-sequence stars in optical SDSS spectra
Authors: Koller, Florian; Leitzinger, Martin; Temmer, Manuela; Odert,
   Petra; Beck, Paul G.; Veronig, Astrid
2021A&A...646A..34K    Altcode: 2020arXiv201200786K
  <BR /> Aims: This work aims to detect and classify stellar flares and
  potential stellar coronal mass ejection (CME) signatures in optical
  spectra provided by the Sloan Digital Sky Survey (SDSS) data release
  14. The sample is constrained to all F, G, K, and M main-sequence
  type stars, resulting in more than 630 000 stars. This work makes
  use of the individual spectral exposures provided by the SDSS. <BR
  /> Methods: An automatic flare search was performed by detecting
  significant amplitude changes in the Hα and Hβ spectral lines after
  a Gaussian profile was fit to the line core. CMEs were searched for
  by identifying asymmetries in the Balmer lines caused by the Doppler
  effect of plasma motions in the line of sight. <BR /> Results: We
  identified 281 flares on late-type stars (spectral types K3 - M9). We
  identified six possible CME candidates showing excess flux in Balmer
  line wings. Flare energies in Hα were calculated and masses of the
  CME candidates were estimated. The derived Hα flare energies range
  from 3 × 10<SUP>28</SUP> - 2 × 10<SUP>33</SUP> erg. The Hα flare
  energy increases with earlier types, while the fraction of flaring times
  increases with later types. Mass estimates for the CME candidates are
  in the range of 6 × 10<SUP>16</SUP> - 6 × 10<SUP>18</SUP> g, and the
  highest projected velocities are ~300-700 km s<SUP>-1</SUP>. <BR />
  Conclusions: The low detection rate of CMEs we obtained agrees with
  previous studies, suggesting that for late-type main-sequence stars the
  CME occurrence rate that can be detected with optical spectroscopy is
  low. <P />Table C.1 is only available at the CDS via anonymous ftp to <A
  href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A>
  (ftp://130.79.128.5) or via <A
  href="http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/646/A34">http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/646/A34</A>

---------------------------------------------------------
Title: Quo vadis, European Space Weather community?
Authors: Lilensten, Jean; Dumbović, Mateja; Spogli, Luca; Belehaki,
   Anna; Van der Linden, Ronald; Poedts, Stefaan; Barata, Teresa; Bisi,
   Mario M.; Cessateur, Gaël; De Donder, Erwin; Guerrero, Antonio;
   Kilpua, Emilia; Korsos, Marianna B.; Pinto, Rui F.; Temmer, Manuela;
   Tsagouri, Ioanna; Urbář, Jaroslav; Zuccarello, Francesca
2021JSWSC..11...26L    Altcode:
  This paper was written by a group of European researchers believing
  that now is the right time to frame the Space Weather and Space
  Climate discipline in Europe for future years. It is devoted to
  openly discussing the organisation and sustainability of the European
  Space Weather community and its assets in the (near) future. More
  specifically, we suggest that the European Space Weather community
  lacks a uniting organisation to help the community to sustain and
  develop the successful efforts made thus far. Our aim is not to draw
  a complete and exhaustive panorama of Space Weather throughout the
  world, nor even throughout Europe. It is not a new white paper on the
  science and applications: there exist many (e.g. Tsurutani et al.,
  2020 Nonlinear Processes Geophys 27(1): 75-119); nor another roadmap:
  several important have been published recently (e.g. Schrijver et al.,
  2015. Adv Space Res 55(12): 2745-2807; Opgenoorth et al., 2019. J Space
  Weather Space Clim 9: A37). Our aim is to question our practices and
  organisation in front of several changes that have occurred in the
  recent years and to set the ground to provide coordinated answers
  to these questions being posed in Europe, and to make these answers
  discussed throughout the world. This group was assembled first through
  a series of sessions devoted to the sustainability of Space Weather
  research during the European Space Weather Week (ESWW) series of
  meetings, specifically: ESWW 14 (2017), ESWW 15 (2018), and ESWW 16
  (2019). It then grew from discussions and personal contacts. The authors
  do not pretend to identify the full range of opinions in Europe,
  although they do come from 13 different European countries with a
  large span of ages (around half are below the age of 40 years old at
  the time of writing) with a good gender balance ending with a diverse
  mix of young and motivated scientists and senior people who have played
  a role in shaping the Space Weather community in Europe. The questions
  and the propositions to organise Space Weather in Europe in the future
  result from their discussions through these meetings and through remote
  meetings during the pandemic. We wish to share them with all those who
  consider themselves as members of the European Space Weather community
  and/or are interested in its future and to propose actions. We do this,
  bearing in mind that Europe plays a key international role in Space
  Weather which extends beyond the ESA and EU/EC geographic area.

---------------------------------------------------------
Title: Statistical Approach on Differential Emission Measure of
    Coronal Holes using the CATCH Catalog
Authors: Heinemann, Stephan G.; Saqri, Jonas; Veronig, Astrid M.;
   Hofmeister, Stefan J.; Temmer, Manuela
2021SoPh..296...18H    Altcode: 2021arXiv210213396H
  Coronal holes are large-scale structures in the solar atmosphere
  that feature a reduced temperature and density in comparison to the
  surrounding quiet Sun and are usually associated with open magnetic
  fields. We perform a differential emission measure analysis on the
  707 non-polar coronal holes in the Collection of Analysis Tools for
  Coronal Holes (CATCH) catalog to derive and statistically analyze
  their plasma properties (i.e. temperature, electron density, and
  emission measure). We use intensity filtergrams of the six coronal EUV
  filters from the Atmospheric Imaging Assembly onboard the Solar Dynamics
  Observatory, which cover a temperature range from ≈10<SUP>5.5</SUP> to
  10<SUP>7.5</SUP>K. Correcting the data for stray and scattered light, we
  find that all coronal holes have very similar plasma properties with an
  average temperature of 0.94 ±0.18 MK, a mean electron density of (2.4
  ±0.7 )×10<SUP>8</SUP>cm−<SUP>3</SUP>, and a mean emission measure
  of (2.8 ±1.6 )×10<SUP>26</SUP>cm−<SUP>5</SUP>. The temperature
  distribution within the coronal holes was found to be largely uniform,
  whereas the electron density shows a 30 to 40% linear decrease from the
  boundary towards the inside of the coronal hole. At distances greater
  than 20″ (≈15 Mm) from the nearest coronal hole boundary, the
  density also becomes statistically uniform. The coronal hole temperature
  may show a weak solar-cycle dependency, but no statistically significant
  correlation of plasma properties with solar-cycle variations could be
  determined throughout the observed period between 2010 and 2019.

---------------------------------------------------------
Title: Towards solving the source to impact chain of Space Weather
    processes
Authors: Temmer, Manuela
2021cosp...43E.643T    Altcode:
  Space Weather is of global and major interest that sustains an exciting
  and wealthy interdisciplinary research community. In that respect,
  science and development of forecasting tools needs to understand the
  chain of action that causes Space Weather, starting from processes at
  the Sun, in interplanetary space, and impact at Earth. The initiative
  called iSWAT (international Space Weather Action Teams) aims towards
  tackling the broad spectrum of issues and addresses individual
  communities to form interdisciplinary partnerships maximizing
  return on investments to national and international space weather
  programs. With that iSWAT fosters information and knowledge exchange
  between international research groups on solar-, heliospheric- and
  geo-space in order to improve existing and to develop new models. In
  that broad spectrum of topics, I will specifically focus on the modeling
  of the background solar wind and embedded coronal mass ejections.

---------------------------------------------------------
Title: Deriving CME Density From Remote Sensing Data and Comparison
    to In Situ Measurements
Authors: Temmer, M.; Holzknecht, L.; Dumbović, M.; Vršnak, B.;
   Sachdeva, N.; Heinemann, S. G.; Dissauer, K.; Scolini, C.; Asvestari,
   E.; Veronig, A. M.; Hofmeister, S. J.
2021JGRA..12628380T    Altcode: 2020arXiv201106880T
  We determine the three dimensional geometry and deprojected mass of 29
  well observed coronal mass ejections (CMEs) and their interplanetary
  counterparts (ICMEs) using combined Solar Terrestrial Relations
  Observatory Solar and Heliospheric Observatory white light data. From
  the geometry parameters, we calculate the volume of the CME for the
  magnetic ejecta (flux rope type geometry) and sheath structure (shell
  like geometry resembling the (I)CME frontal rim). Working under the
  assumption that the CME mass is roughly equally distributed within a
  specific volume, we expand the CME self similarly and calculate the CME
  density for distances close to the Sun (15-30 Rs) and at 1 AU. Specific
  trends are derived comparing calculated and in situ measured proton
  densities at 1 AU, though large uncertainties are revealed due to the
  unknown mass and geometry evolution: (1) a moderate correlation for
  the magnetic structure having a mass that stays rather constant (cc
  ≈ 0.56 - 0.59), and (2) a weak correlation for the sheath density (cc
  ≈ 0.26) by assuming the sheath region is an extra mass—as expected
  for a mass pile up process—that is in its amount comparable to the
  initial CME deprojected mass. High correlations are derived between in
  situ measured sheath density and the solar wind density (cc ≈ -0.73)
  and solar wind speed (cc ≈ 0.56) as measured 24 h ahead of the arrival
  of the disturbance. This gives additional confirmation that the sheath
  plasma indeed stems from piled up solar wind material. While the CME
  interplanetary propagation speed is not related to the sheath density,
  the size of the CME may play some role in how much material could be
  piled up.

---------------------------------------------------------
Title: Improving Understanding and Assessment of the Ambient
    Solar Wind
Authors: Reiss, Martin; Moestl, Christian; Linker, Jon; Mullinix,
   Richard; Rastaetter, Lutz; Temmer, Manuela; Arge, Charles; MacNeice,
   Peter; Wiegand, Chiu; Muglach, Karin; Ko, Kuen
2021cosp...43E2398R    Altcode:
  The Sun's magnetic field drives the evolving ambient solar wind flow
  and the magnetic field embedded within it. Thus, studying the magnetic
  field configuration in the solar atmosphere is of crucial importance
  for improving our understanding of and ultimately predicting space
  weather from Sun to Earth. Coronal holes are regions of low intensity
  emission in EUV and X-ray images. Coronal holes are closely associated
  with open magnetic field lines, along which the solar wind accelerates
  to supersonic speeds. Therefore, they play a central role in shaping
  the structure of the heliosphere and defining key properties in
  interplanetary space, such as the solar wind bulk speed, magnetic field
  strength, and field orientation. Answering vital research questions
  related to the ambient solar wind requires an interdisciplinary strategy
  and the coordinated collaboration of international partners. Here we
  present the COSPAR ISWAT activities for improving the understanding
  and assessment of the evolving ambient solar wind flow embedded in
  the 'Coronal Hole Boundary Working Team' and the 'Ambient Solar
  Wind Validation Team'. Specifically, we present our progress in
  evaluating the uncertainty of coronal hole boundary locations in
  solar observations, and our progress in establishing an online hub for
  validation of ambient solar wind models. In context, we demonstrate
  the first application of a new online platform enabling developers
  and end-users to directly assess the quality of state-of-the-art
  solar wind model solutions. To conclude, we present the objectives,
  current status and roadmaps of both action teams, and discuss the main
  challenges we face in the realization of our objectives.

---------------------------------------------------------
Title: Life-time evolution and magnetic structure of coronal holes
Authors: Heinemann, Stephan; Pomoell, Jens; Temmer, Manuela; Bourdin,
   Philippe
2021cosp...43E1024H    Altcode:
  The study of the evolution of coronal holes (CHs) is especially
  important in the context of high--speed solar wind streams
  emanating from them. Slow and high speed stream interaction
  regions may deliver large amount of energy into the Earth's
  magnetosphere-termosphere-ionosphere system system, cause geomagnetic
  storms, and shape interplanetary space. The open magnetic structure,
  its evolution and interplay with the local and global fields strongly
  defines the coronal and solar wind properties. Only by understanding
  these we can attempt to create a full picture of our heliosphere. By
  statistically investigating the long--term evolution of 16 well
  observed CHs, which are distributed in time over a full solar cycle,
  we aim to reveal processes that drive the observed changes in the
  CH parameters. We use remote sensing image data from SDO and focus
  on coronal, morphological and underlying photospheric magnetic field
  characteristics as well as investigate the evolution of the associated
  high--speed streams from in-situ measurements. The analysis of the
  observational data is supported by modeling, based on synthetic data
  in order to simulate the small-scale magnetic field topology in 3
  dimensions. We find that the CH area evolution mostly shows a rough
  trend of growing to a maximum followed by a decay. No correlation of
  the area evolution to the evolution of the signed magnetic flux and
  signed magnetic flux density enclosed in the projected coronal hole
  area was found. From this we conclude that the magnetic flux within
  the extracted coronal hole boundaries is not the main cause for its
  area evolution. This is supported by the model results. Change rates
  of the signed mean magnetic flux density and the signed magnetic flux
  are derived to be dependent on the solar cycle rather than on the
  evolution of the individual CH. This clearly hints towards that the
  global magnetic field gives significant contribution to the evolution
  of open magnetic field structures on the Sun. The velocities of the
  high speed streams emanating from the CHs are found to be linearly
  related to the area of the individual CH, however the slopes vary.

---------------------------------------------------------
Title: Forecasting the arrival time of coronal mass ejections
Authors: Dumbovic, Mateja; Mays, M. Leila; Riley, Pete; Mierla,
   Marilena; Kay, Christina; Vrsnak, Bojan; Veronig, Astrid; Cremades,
   Hebe; Čalogović, Jaša; Verbeke, Christine; Temmer, Manuela; Sudar,
   Davor; Scolini, Camilla; Hinterreiter, Jürgen; Paouris, Evangelos;
   Palmerio, Erika; Balmaceda, Laura
2021cosp...43E1038D    Altcode:
  Forecasting the arrival time of coronal mass ejections (CMEs) and their
  associated shocks is one of the key aspects of space weather. In recent
  years many models have been developed by various research groups aiming
  to forecast CME arrival time. The models differ based on the input,
  approach, assumptions and complexity ranging from simple empirical and
  analytical to complex numerical and machine learning models. One of the
  commonly used models is, due to its simplicity and calculation speed,
  the analytical drag-based (ensemble) model [DB(E)M] for heliospheric
  propagation of CMEs. DB(E)M relies on the observational fact that
  slow CMEs accelerate whereas fast CMEs decelerate, and is based on
  the concept of MHD drag, which acts to adjust the CME speed to the
  ambient solar wind. However, regardless of the model, forecasting CME
  arrival time has proven to be exceedingly challenging. One of the major
  setbacks is the uncertainty of the CME observational input, which
  is still substantial despite state-of-the-art remote observational
  capacities such as high-resolution EUV imagers and stereoscopic
  observations. Another major setback is the uncertainty in the CME
  propagation itself, due to e.g. unrealistic background solar wind
  and/or complex interactions. These limits will be discussed in the
  scope of DB(E)M and the CME input analysis performed by the ISSI Bern
  team on the "Understanding Our Capabilities In Observing And Modeling
  Coronal Mass Ejections".

---------------------------------------------------------
Title: Stereoscopic view on CMEs; differences in predicted CME
    arrivals based on STEREO-A/STEREO-B HI data
Authors: Hinterreiter, Jürgen; Moestl, Christian; Amerstorfer, Ute;
   Amerstorfer, Tanja; Temmer, Manuela; Reiss, Martin; Bailey, Rachel;
   Weiss, Andreas J.; Bauer, Maike
2021cosp...43E1039H    Altcode:
  Over the last decades numerous models to predict the arrival times
  and speeds of CMEs (coronal mass ejections) have been developed. They
  range from computationally very fast drag-based models to expensive
  MHD models. However, uncertainties in the forecasts are large for all
  the models available so far. In this study, we use ELEvoHI (ELlipse
  Evolution model based on Heliospheric Imager observations) ensemble
  modeling for CME post-event arrival prediction. The model assumes an
  elliptical shape of the CME front within the ecliptic plane and makes
  use of time-elongation profiles provided by HI (Heliospheric Imager)
  onboard the STEREO (Solar TErrestrial RElations Observatory) twin
  spacecraft. In addition, ELEvoHI utilizes an ambient solar wind provided
  by the Wang-Sheeley-Arge model to account for the drag force that is
  exerted on the CME during the propagation in the heliosphere. For
  this study, we carefully select 12 CMEs between February 2010 and
  July 2012. The CMEs have to fulfill the following three criteria: 1)
  clear signatures in STEREO-A and STEREO-B HI images, 2) corresponding
  in-situ signature, and 3) propagation close to the ecliptic plane. Based
  on typical input data we analyze the arrival times and speeds of each
  CME using STEREO-A and STEREO-B time-elongation profiles and compare
  them with each other. The results show differences up to 10 hours and
  200 km/s. We give possible reasons for the discrepancies in relation
  to the input data and dependencies on the two vantage points.

---------------------------------------------------------
Title: ISWAT H2 Cluster: CME structure, evolution and propagation
    through heliosphere
Authors: Verbeke, Christine; Mays, M. Leila; Temmer, Manuela; Kay,
   Christina
2021cosp...43E2417V    Altcode:
  Coronal mass ejections (CMEs) are energetically the most powerful
  phenomena in the solar system. Most of the times related to solar
  flare emissions, CMEs consist of magnetic field and plasma that is
  impulsively ejected into interplanetary space. To make progress in
  improving current state-of-the-art CME propagation models, validation
  and scientific peer-review qualification is needed. iSWAT is an
  international, community driven effort and provides the required
  platform to challenge currentmodels and to exchange our experience
  with peers in order to improve our work. We give an overview on the
  available teams in the H2 cluster and their aims for the H2 cluster.

---------------------------------------------------------
Title: Observational study of CME propagation and geo-effectiveness
Authors: Temmer, Manuela
2021cosp...43E1784T    Altcode:
  Coronal mass ejections (CMEs) are the most powerful dynamic phenomena in
  our solar system. The propagation behavior of these transient events in
  interplanetary space is strongly dependent on their initial parameters,
  like size and mass, kinematics, and the ambient solar wind structure. As
  CMEs evolve, different structures are observed, typically covering a
  shock-sheath region and a driver, pre-sumably consisting of a magnetic
  flux rope. The structures can be observed and distinguished partly in
  remote sensing image data and more clearly from in-situ measurements
  by their different character-istics. Both structures undergo changes
  on their way from Sun to Earth that modifies the degree of impact and
  geoeffectiveness. While during propagation presumably mass is built up
  in the sheath's front region, the orientation of the interplanetary
  magnetic field affects the magnetic structure by re-ducing or
  increasing the amount of magnetic flux due to reconnection with the
  interplanetary magnetic field. When hitting Earth, differences in
  the magnetospheric responses are found between the magnetic and the
  shock-sheath region. This talk will review different perspectives of
  CME evolution in inter-planetary space and their interaction with the
  solar wind, with special aspects from new solar missions Parker Solar
  Probe and Solar Orbiter.

---------------------------------------------------------
Title: Statistical Analysis of SDO-era Coronal Holes using CATCH
Authors: Heinemann, Stephan; Temmer, Manuela
2021cosp...43E1014H    Altcode:
  Coronal holes are regions of open magnetic field configuration in the
  solar corona and can be observed as large-scale dark structures in the
  extreme ultraviolet and X-ray spectrum. Deriving reliably the coronal
  hole boundary is crucial, as its area, underlying magnetic field, and
  other properties such as shape and intensity, give important hints
  towards high speed solar wind acceleration processes. In this study
  we present a new threshold-based extraction method that is modulated
  using the intensity gradient along the coronal hole boundary. It is
  implemented as a user-friendly SSWIDL-GUI and is part of the official
  distribution. The Collection of Analysis Tools for Coronal Holes
  (CATCH) enables the user to download data, perform guided coronal hole
  extraction and analyze the underlying photospheric magnetic field. We
  used CATCH to evaluate all non-polar coronal holes of the SDO-era. We
  used 193 Å filtergrams taken by the Atmospheric Imaging Assembly
  (AIA) and line-of-sight magnetograms taken by the Heliospheric and
  Magnetic Imager (HMI), both on board the Solar Dynamics Observatory
  (SDO) to investigate 707 coronal holes near the central meridian during
  the time period of 2010 and 2019. We find coronal holes distributed
  across latitudes of $\pm 60^\circ$ and sizes between $1.6\times10^9$
  km$^{2}$. to $1.8\times10^{11}$ km$^{2}$. The absolute value of the
  mean signed magnetic field strength is on average of 2.9$\pm$1.9 G. We
  find no distinct trend towards a preferred hemisphere in abundance
  or size. Variations in the local and global conditions significantly
  change the threshold needed for reliable coronal hole extraction and
  thus, we can highlight the importance of individually assessing and
  extracting coronal holes.

---------------------------------------------------------
Title: The COSPAR ISWAT initiative for open validation analysis for
    models of the evolving ambient solar wind
Authors: Reiss, Martin; Kuznetsova, Maria; Mullinix, Richard;
   Rastaetter, Lutz; Temmer, Manuela; MacNeice, Peter; Wiegand, Chiu;
   Muglach, Karin
2021cosp...43E2363R    Altcode:
  Validation analysis plays a critical role in applied space weather
  research and prediction. First and foremost to inform developers and
  users of space weather models about the strengths and weaknesses of
  the models, and also to provide an unbiased assessment of progress
  over time. Here we present the activities of the Ambient Solar Wind
  Validation Team embedded in the COSPAR ISWAT initiative. The objective
  of this action team is to establish an online hub for validation
  analysis of ambient solar wind models in correspondence with the
  space weather community, allowing developers and end-users to directly
  assess the quality of state-of-the-art model solutions. To this end,
  we choose and agree on a set of comprehensive validation metrics
  reflecting the community needs and integrate them into the existing
  Comprehensive Assessment of Models and Events using Library Tools
  (CAMEL) web application hosted by NASA's Community Coordinated Modelling
  Center. CAMEL is an interactive visualization tool allowing developers
  and users to compare space weather and space science model output to
  observations. Specifically, we make use of CAMEL to quantitatively
  assess the relationship between state-of-the-art solar wind model
  solutions and observational data in terms of point-to-point statistics
  and more advanced event-based validation measures. In this presentation,
  we will demonstrate the first application of the new online platform
  with examples of state-of-the-art model solutions. We will also discuss
  the main challenges we face in the realization of our objectives,
  and present the current status and the roadmap of the action team.

---------------------------------------------------------
Title: Estimating the magnetic flux within an eruptive flux rope
Authors: Temmer, Manuela; Rodriguez, Luciano; Dissauer, Karin; Veronig,
   Astrid; Tschernitz, Johannes; Thalmann, Julia K.; Hinterreiter, Jürgen
2021cosp...43E1741T    Altcode:
  Erupting magnetic flux ropes develop into coronal mass ejections (CMEs)
  as they evolve and finally propagate into interplanetary space. Those
  large scale eruptions are observed to be frequently related to dynamic
  surface phenomena such as coronal waves and dimming regions. The better
  we are able to estimate initial CME parameters such as kinematics,
  geometry, and magnetic properties, the more precisely we can feed
  state-of-the-art CME propagation models and with that improve CME
  forecasting. In that respect, we report on a well-observed flare-CME
  event from 1 October 2011 focusing on the dynamic evolution of the
  CME and its embedded magnetic field. Using combined STEREO and SDO
  observations together with nonlinear force-free (NLFF) modeling we
  derive separately the flare reconnection and dimming flux. We find
  that already before the start of the impulsive flare phase magnetic
  reconnection was ongoing, that added magnetic flux to the flux rope
  before its final eruption. As the dimming evolves over a longer time
  span than the flaring phase, we find that the dimming flux increases by
  more than 25% after the end of the flare. This indicates that magnetic
  flux is still added to the flux rope after eruption and that the derived
  flare reconnection flux is most probably a lower limit for estimating
  the magnetic flux within the flux rope.

---------------------------------------------------------
Title: Modeling Coronal Mass Ejections with EUHFORIA
Authors: Verbeke, Christine; Schmieder, Brigitte; Rodriguez, Luciano;
   Poedts, Stefaan; Magdalenic, Jasmina; Pomoell, Jens; Temmer, Manuela;
   Asvestari, Eleanna; Scolini, Camilla; Heinemann, Stephan; Hinterreiter,
   Jürgen; Samara, Evangelia
2021cosp...43E2358V    Altcode:
  Fully understanding the origin and evolution of Coronal Mass Ejections
  (CMEs) from the Sun to the Earth remains a major topic in current
  solar-terrestrial physics and is of key importance to improve our space
  weather prediction capabilities. CMEs can drive strong space weather
  disturbances at Earth, and their dynamical pressure, magnetic field
  configuration and interaction with the solar wind can significantly
  alter their arrival time and impact at Earth. One of the key parameters
  that determine the geo-effectiveness of the CME is its internal magnetic
  configuration. With the EUHFORIA inner-heliosphere magnetohydrodynamics
  model, we can model a magnetised CME using a Linear Force Free Spheromak
  (LFFS) model, in order to model the internal magnetic structure of
  the CME throughout the inner heliosphere. In this talk, we present
  an overview of the model assessment efforts that have been made
  with EUHFORIA over the past years. We discuss the validation of the
  solar wind, as well as the development of the LFFS model. We focus
  on determining the sensitivity of the LFFS model input parameters,
  as well as some case studies to show our improved modeling of the
  CME magnetic field structures at Earth. Finally, we discuss current
  limitations and future improvements of the EUHFORIA model.

---------------------------------------------------------
Title: CME evolution and the corresponding Forbush decrease: modelling
    vs multi-spacecraft observation
Authors: Dumbovic, Mateja; Moestl, Christian; Podladchikova, Tatiana;
   Guo, Jingnan; Heber, Bernd; Vrsnak, Bojan; Dissauer, Karin; Veronig,
   Astrid; Amerstorfer, Tanja; Temmer, Manuela; Carcaboso, Fernando;
   Kirin, Anamarija
2021cosp...43E1747D    Altcode:
  One of the very common in-situ signatures of interplanetary coronal
  mass ejections (ICMEs), as well as other interplanetary transients are
  Forbush decreases (FDs), i.e. short-term reductions in the galactic
  cosmic ray (GCR) flux. FD phenomena are caused by the interaction
  of GCRs with a magnetic structure, therefore it is expected that
  different types of interplanetary substructures cause different types
  of GCR time profiles, allowing us to distinguish between shock/sheath,
  flux rope and SIR-type of FDs. Moreover, since the interaction of
  GCRs and CME magnetic structure (i.e. flux rope) occurs all the
  way from Sun to Earth, FDs reflect the evolutionary properties of
  CMEs. We apply modelling to different ICME regions in order to obtain
  a generic FD profile. We model the shock/sheath-related FD using the
  propagating diffusive barrier (PDB) model, the flux-rope-related FD
  using the diffusion model for the expanding flux rope (ForbMod),
  and the exponential time profile approximates the recovery after
  the event. The modeled generic FD profile qualitatively agrees with
  our current observation-based understanding of FDs. In addition, we
  test ForbMod against a set of multi-spacecraft observations of the
  same ICME. We find a reasonable agreement of the ForbMod model with
  multi-spacecraft measurements, indicating that modelled FDs reflect
  well the flux rope evolution.

---------------------------------------------------------
Title: Evolution of coronal mass ejections and the corresponding
Forbush decreases: modelling vs. multi-spacecraft observations
Authors: Dumbovic, M.; Vrsnak, B.; Guo, J.; Heber, B.; Dissauer, K.;
   Carcaboso-Morales, F.; Temmer, M.; Veronig, A.; Podladchikova, T.;
   Moestl, C.; Amerstorfer, T.; Kirin, A.
2020AGUFMSH046..08D    Altcode:
  One of the very common in situ signatures of interplanetary coronal
  mass ejections (ICMEs), as well as other interplanetary transients,
  are Forbush decreases (FDs), i.e. short-term reductions in the galactic
  cosmic ray (GCR) flux. A two-step FD is often regarded as a textbook
  example, which presumably owes its specific morphology to the fact that
  the measuring instrument passed through the ICME head-on, encountering
  first the shock front (if developed), then the sheath and finally the
  CME magnetic structure. The interaction of GCRs and the shock/sheath
  region, as well as the CME magnetic structure, occurs all the way from
  Sun to Earth, therefore, FDs are expected to reflect the evolutionary
  properties of CMEs and their sheaths. We apply modelling to different
  ICME regions in order to obtain a generic two-step FD profile, which
  qualitatively agrees with our current observation-based understanding of
  FDs. We next adapt the models for energy dependence to enable comparison
  with different GCR measurement instruments (as they measure in different
  particle energy ranges). We test these modelling efforts against a
  set of multi-spacecraft observations of the same event, using the
  Forbush decrease model for the expanding flux rope (ForbMod). We find
  a reasonable agreement of the ForbMod model for the GCR depression
  in the CME magnetic structure with multi-spacecraft measurements,
  indicating that modelled FDs reflect well the CME evolution.

---------------------------------------------------------
Title: Drag-based Forecast for CME Arrival
Authors: Yordanova, E.; Jaklovsky, S.; Dumbovic, M.; Temmer, M.;
   Dimmock, A. P.; Rosenqvist, L.
2020AGUFMSH0030013Y    Altcode:
  The accurate estimation of the CME arrival times at 1 AU is of key
  importance for space weather forecast. It is a challenging issue, since
  when a CME expands, it inevitably interacts with the solar corona and
  the ambient solar wind occupying the interplanetary space. This often
  results in modification of the CME's plasma properties and propagation
  path. There are various approaches in use for arrival time prediction -
  either based on MHD modeling or empirical relations between parameters
  measured from coronagraphs and in-situ at L1. Here, we investigate the
  performance of the recent Drag Based Ensemble Model (DBEM, Dumbović et
  al., 2018; Žic et al., 2015) available for users from the ESA Space
  Situational Awareness Portal (http://swe.ssa.esa.int). DBEM provides
  an ensemble of probabilistic predictions for CME arrivals based on the
  Drag-Based Model (DBM, Vršnak et al., 2013) which assumes that the
  propagation of a CME is dependent solely on the magnetohydrodynamic
  drag (in analogy to the aerodynamic drag) exerted to the CME from the
  ambient solar wind. <P />We have selected to test a set of twelve
  geoeffective Earth-directed fast halo CMEs. For the model runs, we
  use as input CMEs' shock speed and the velocity of the respective
  preceding solar wind measured by WIND spacecraft. We perform test
  runs with values of the drag parameter: (0.1, 0.2 and 0.3)x10<SUP>-7
  </SUP>km<SUP>-1</SUP>. Overall, the model produced a wide distribution
  of arrival times. The predictions were rather good, being confined in
  the range of ± 10 h. In addition, the model provides prediction for
  the CME arrival speeds, which in our case seem to be overestimated for
  all drag values. The closest predicted arrival time to about -2.5 h
  on average, was achieved by setting the drag value to 0.2x10<SUP>-7
  </SUP>km<SUP>-1</SUP>. When matching also the predicted to the
  observed arrival speeds, the best average result was achieved with drag
  parameter 0.3x10<SUP>-7 </SUP>km<SUP>-1</SUP>, corresponding to +4.5
  h CME arrival time. These drag values are higher than the recommended
  0.1x10<SUP>-7 </SUP>km<SUP>-1</SUP> for fast CMEs, suggesting that the
  exerted solar wind drag was higher than anticipated. This implies that
  further improvement in the CME arrival forecast requires more detailed
  and precise knowledge of the preconditioning of the interplanetary
  space through which the CMEs are propagating. <P />References:
  <P />Dumbović, M., et al., The Drag-based Ensemble Model (DBEM)
  for Coronal Mass Ejection Propagation. Astrophys. J., 854:180,
  2018 <P />Žic, M. et al., Heliospheric Propagation of Coronal Mass
  Ejections: Drag-based Model Fitting. Astrophys. J. Suppl., 218:32,
  2015 <P />Vršnak, B., et al., Propagation of Interplanetary Coronal
  Mass Ejections: The Drag-Based Model, Solar Phys. 285:295-315, 2013

---------------------------------------------------------
Title: CME-CME Interactions as Sources of CME Helio-Effectiveness:
    the Early September 2017 Events
Authors: Scolini, C.; Chané, E.; Temmer, M.; Pomoell, J.; Kilpua,
   K. E. J.; Dissauer, K.; Veronig, A.; Palmerio, E.; Dumbovic, M.; Guo,
   J.; Rodriguez, L.; Poedts, S.
2020AGUFMSH0440017S    Altcode:
  Coronal Mass Ejections (CMEs) are the main source of intense space
  weather disturbances in the heliosphere. It is known that the
  capability of individual CMEs to drive strong space weather events
  at Earth (called "geo-effectiveness") and other locations (here
  referred to as "helio-effectiveness") primarily depends on their
  speed, density, and magnetic field strength and orientation at the
  impact location. Moreover, previous studies established that CME--CME
  interactions can significantly alter the properties of individual
  CMEs, in such a way that their geo-effectiveness is often dramatically
  amplified. However, the actual quantification of this amplification has
  been rarely investigated, and previous studies have mostly focused on
  the near-Earth region only, i.e. without considering its full space-time
  evolution as the CMEs propagate to 1 AU and beyond. <P />Here, we
  present a study on the role of CME--CME interactions as sources of CME
  helio-effectiveness by performing simulations of complex CME events
  with the EUHFORIA heliospheric model. As a case study, we consider
  a sequence of CMEs observed in early September 2017. As their source
  region rotated on the solar disk, CMEs were launched over a wide range
  of longitudes, interacting with each other and paving the way for the
  propagation of the following ones. At Earth, their interaction resulted
  in an intense geomagnetic storm. Using initial parameters derived
  from remote-sensing observations, we perform global simulations of
  magnetised CMEs with EUHFORIA, investigating how their interactions
  affected the propagation and internal properties of individual CME
  structures. Taking advantage of 3D simulation outputs, we quantify
  the amplification of the helio-effectiveness of the individual CMEs
  involved, as a function of the interaction phase and of the location
  within the CME structure. Additionally, we explore the possibility of
  the existence of a "helio-effectiveness amplification zone", i.e. a
  characteristic heliocentric distance at which CME--CME interactions have
  the highest probability to develop into helio-effective events. Results
  from this study benchmark our current prediction capabilities in
  the case of complex CME events, and provide new insights on their
  large-scale evolution and potential impact throughout the heliosphere.

---------------------------------------------------------
Title: Characteristics of a long-lived CIR and the corresponding
    depression in the GCR flux
Authors: Dumbovic, M.; Vrsnak, B.; Temmer, M.; Heber, B.
2020AGUFMSH0440026D    Altcode:
  We observe a long-lived CIR recurring in 27 consecutive Carrington
  rotations 2057-2083 in the time period from June 2007 - May 2009. We
  characterize the in situ measurements of this long-lived CIR as well as
  the corresponding depression in the GCR count observed by SOHO/EPHIN,
  and analyze them throughout different rotations. We find that the
  behavior of the flow speed peak roughly shows a rising phase and
  a declining phase. This is similar to the evolutionary profile of
  some observed coronal hole areas, but without a clear peak. The GCR
  count evolutionary profile roughly follows that of the flow speed
  peak, but moreover we find that the inverted GCR count time-profile
  matches very well with that of the flow speed throughout different
  rotations. We perform a statistical analysis and find the GCR count
  amplitude correlated to the peak in the magnetic field and flow
  speed, as expected based on previous statistical studies. In order
  to characterize a generic CIR profile for modelling purposes, we
  perform the superposed epoch analysis using relative values of the
  key parameters. Based on the observed properties we propose a simple
  analytical model starting from the basic Fokker-Planck equation.

---------------------------------------------------------
Title: COSPAR International Space Weather Action Teams: Addressing
    Challenges Across the Field of Space Weather.
Authors: Kuznetsova, M. M.; Belehaki, A.; Bisi, M. M.; Bruinsma, S.;
   Fung, S. F.; Glover, A.; Grande, M.; Guo, J.; Jun, I.; Linker, J.;
   Mann, I. R.; Masson, A.; Mendoza, A. M. M.; Murray, S. A.; Nandy, D.;
   Opgenoorth, H. J.; Pevtsov, A. A.; Plainaki, C.; Reiss, M.; Sutton,
   E. K.; Temmer, M.; Usoskin, I. G.; Yao, Z.; Yardley, S.; Zheng, Y.
2020AGUFMSH0030022K    Altcode:
  Advanced predictions of space weather impacts require improved
  understanding and modeling capabilities of coupled chains of space
  environment processes. It is necessary to assemble parts of the
  source-to-impact puzzle by identifying, addressing and solving
  problems focused on specific physical domains, and then to connect
  all validated solutions from space weather origins on the sun to
  impacts on coupled geospace system, humans and technologies. To
  address the need for multi-disciplinary international space weather
  research community connecting experts in space weather phenomena
  across all domains and experts in space environment impact,
  the COSPAR Panel on Space Weather facilitated establishment of
  a network of International Space Weather Action Teams (ISWAT, <A
  href="https://www.iswat-cospar.org">https://www.iswat-cospar.org</A>,
  @IswatCosparOrg). ISWAT serves as a global hub for community coordinated
  topical collaborations focused on different aspects of space weather
  including advancing understanding, assessment and improvement of
  modeling capabilities, transitioning advances in research to operations,
  optimized utilization of available observations, and generating inputs
  to future instrumentation deployment. Action teams are building
  blocks of ISWAT initiative. ISWAT action teams are organized into
  domain-based ISWAT clusters. Action teams are working in coordinated
  effort across physical domain and across borders. The primary ISWAT
  goal is to advance space weather predictive capabilities based on best
  science available. The ISWAT currently includes more than 250 active
  participants and more than 50 action teams. The presentation will
  overview the outcome from the COSPAR ISWAT Inaugural Working Meeting
  in February 2020, highlight recent progress in advancing physics-based
  predictive capabilities and discuss plans for transforming COSPAR space
  weather Roadmap into a living document maintained by the community.

---------------------------------------------------------
Title: Exploration and Forecasting of Thermospheric Variations at
    Different Altitudes Within the Framework of Project SWEETS
Authors: Krauss, S.; Suesser-Rechberger, B.; Temmer, M.; Mayer-Guerr,
   T.; Drescher, L.; Kroisz, S.
2020AGUFMSM050..09K    Altcode:
  Owing to advances in solar research in the recent decades, today we know
  that coronal mass ejections (CMEs) cause the most comprehensive spectrum
  of space weather disturbances. These huge clouds of magnetized plasma
  are propagating from the solar corona into interplanetary space with
  typical transit times that range between two and five days, depending on
  the initial speed, the mass, the size as well as the speed and density
  of the surrounding solar wind plasma. During strong geomagnetic storms,
  induced by CMEs, the neutral density of the Earth's thermosphere is
  subject to strong fluctuations and, thus, a critical parameter for low
  Earth-orbiting satellites. The enhanced energy input from the solar
  wind to the magnetosphere causes heating and expansion of the Earth's
  thermosphere, which affects Earth-orbiting satellites in such a way
  that the drag force acting on the spacecraft is enhanced and leads
  to an additional storm induced orbit decay. <P />Within the project
  SWEETS (FFG funded) it is intended to develop a forecasting model, to
  predict the expected impact of solar events on satellites at different
  altitudes between 300-800 km. For the realization, scientific data,
  such as kinematic orbit information and accelerometer measurements,
  from a wide variety of satellites will be incorporated. Through a
  joint analysis and evaluation of solar wind plasma and magnetic field
  data observed at the Lagrange point L1, first preliminary results of
  predicted thermospheric density increases and associated satellite
  orbit decay rates are shown.

---------------------------------------------------------
Title: VizieR Online Data Catalog: Search for flares and CMEs in
    SDSS data (Koller+, 2021)
Authors: Koller, F.; Leitzinger, M.; Temmer, M.; Odert, P.; Beck,
   P. G.; Veronig, A.
2020yCat..36460034K    Altcode:
  This file contains the complete list of flares found by this work
  and their most important derived or collected parameters. The
  in-depth description of the derivation of these parameters is given
  in the article. <P />The optical spectra by SDSSS data release 14
  (2018ApJS..235...42A) that we used in this work consist of several
  single spectra, which are combined to a final coadded spectrum for each
  observed object. We used the single spectra to find temporal changes
  in Balmer lines, indicating flaring events. With the latest GAIA data
  release (2018A&amp;A...616A...1G), we were able to derive energy and
  luminosity values for the flares. We focused on the Halpha Balmer line
  due to the better S/N. Our methods were based on line fitting algorithms
  to detect changes from one observation to another. <P />Similar to
  the work by Hilton et al. (2010, Cat. J/AJ/140/1402) we give stellar
  coordinates as RAdeg and DEdeg as the first parameters to distinguish
  between the objects. In addition to that, the Plate-MJD-Fiber number
  serves as a unique identifier for the flaring SDSS spectrum. The stellar
  position is not enough because objects can be observed multiple times
  at different surveys by SDSS, resulting in different sets of single
  spectra. The method and the categorization of the S/N bins are defined
  in the article. <P />The spectral type classified by SDSS and by
  other literature is given. The distance and the source for the value
  is given when possible. The defined quiet flag and the consideration
  flag give insight on the reliability of the derived values. Whether a
  flare was also detected in Hilton et al. (2010, Cat. J/AJ/140/1402) is
  given in a separate column. The flare energy, the luminosity, and the
  associated errors were derived using the SDSS spectra as is described
  in the article (see Sect.4.2.2) and given here in units of W and W/s
  (J). <P />The peak spectrum and the spectrum used in the calculation as
  the reference are given. Their number refer to the chronological order
  of the single spectra. The number of available single spectra (in the
  optical red domain containing Halpha) and the number of single spectra
  in a flaring state are given. The overall time of these flaring spectra
  is summed and given in units of minutes. <P />Additional comments made
  during the visual inspection of all flaring spectra are added. <P />(1
  data file).

---------------------------------------------------------
Title: A new method for estimating global coronal wave properties
    based on their interaction with solar coronal holes
Authors: Piantschitsch, I.; Terradas, J.; Temmer, M.
2020A&A...641A..21P    Altcode: 2020arXiv200607293P
  Among the effects of interactions between global coronal waves (CWs)
  and coronal holes (CHs) is the formation of reflected and transmitted
  waves. Observations of such events provide us with measurements
  of different CW parameters, such as phase speed and intensity
  amplitudes. However, several of these parameters are provided with
  only intermediate observational quality, whereas other parameters,
  such as the phase speed of transmitted waves, can hardly be observed
  in general. We present a new method to estimate crucial CW parameters,
  such as density and phase speed of reflected as well as transmitted
  waves, Mach numbers and density values of the CH's interior, by using
  analytical expressions in combination with the most basic and most
  accessible observational measurements available. The transmission and
  reflection coefficients were derived from linear theory and used to
  calculate estimations for phase speeds of incoming, reflected, and
  transmitted waves. The obtained analytical expressions were validated
  by performing numerical simulations of CWs interacting with CHs. This
  new method enables us to determine in a fast and straightforward way
  reliable CW and CH parameters from basic observational measurements
  which provides a powerful tool to better understand the observed
  interaction effects between CWs and CHs.

---------------------------------------------------------
Title: Solar Flare-CME Coupling throughout Two Acceleration Phases
    of a Fast CME
Authors: Gou, Tingyu; Veronig, Astrid M.; Liu, Rui; Zhuang, Bin;
   Dumbović, Mateja; Podladchikova, Tatiana; Reid, Hamish A. S.; Temmer,
   Manuela; Dissauer, Karin; Vršnak, Bojan; Wang, Yuming
2020ApJ...897L..36G    Altcode: 2020arXiv200611707G
  Solar flares and coronal mass ejections (CMEs) are closely coupled
  through magnetic reconnection. CMEs are usually accelerated impulsively
  within the low solar corona, synchronized with the impulsive flare
  energy release. We investigate the dynamic evolution of a fast CME and
  its associated X2.8 flare occurring on 2013 May 13. The CME experiences
  two distinct phases of enhanced acceleration, an impulsive one with a
  peak value of ∼5 km s<SUP>-2</SUP>, followed by an extended phase with
  accelerations up to 0.7 km s<SUP>-2</SUP>. The two-phase CME dynamics
  is associated with a two-episode flare energy release. While the first
  episode is consistent with the "standard" eruption of a magnetic flux
  rope, the second episode of flare energy release is initiated by the
  reconnection of a large-scale loop in the aftermath of the eruption
  and produces stronger nonthermal emission up to γ-rays. In addition,
  this long-duration flare reveals clear signs of ongoing magnetic
  reconnection during the decay phase, evidenced by extended hard X-ray
  bursts with energies up to 100-300 keV and intermittent downflows
  of reconnected loops for &gt;4 hr. The observations reveal that the
  two-step flare reconnection substantially contributes to the two-phase
  CME acceleration, and the impulsive CME acceleration precedes the most
  intense flare energy release. The implications of this non-standard
  flare/CME observation are discussed.

---------------------------------------------------------
Title: Evolution of Coronal Mass Ejections and the Corresponding
Forbush Decreases: Modeling vs. Multi-Spacecraft Observations
Authors: Dumbović, Mateja; Vršnak, Bojan; Guo, Jingnan; Heber,
   Bernd; Dissauer, Karin; Carcaboso, Fernando; Temmer, Manuela; Veronig,
   Astrid; Podladchikova, Tatiana; Möstl, Christian; Amerstorfer, Tanja;
   Kirin, Anamarija
2020SoPh..295..104D    Altcode: 2020arXiv200602253D
  One of the very common in situ signatures of interplanetary coronal
  mass ejections (ICMEs), as well as other interplanetary transients,
  are Forbush decreases (FDs), i.e. short-term reductions in the galactic
  cosmic ray (GCR) flux. A two-step FD is often regarded as a textbook
  example, which presumably owes its specific morphology to the fact that
  the measuring instrument passed through the ICME head on, encountering
  first the shock front (if developed), then the sheath, and finally the
  CME magnetic structure. The interaction of GCRs and the shock/sheath
  region, as well as the CME magnetic structure, occurs all the way from
  Sun to Earth, therefore, FDs are expected to reflect the evolutionary
  properties of CMEs and their sheaths. We apply modeling to different
  ICME regions in order to obtain a generic two-step FD profile, which
  qualitatively agrees with our current observation-based understanding
  of FDs. We next adapt the models for energy dependence to enable
  comparison with different GCR measurement instruments (as they measure
  in different particle energy ranges). We test these modeling efforts
  against a set of multi-spacecraft observations of the same event, using
  the Forbush decrease model for the expanding flux rope (ForbMod). We
  find a reasonable agreement of the ForbMod model for the GCR depression
  in the CME magnetic structure with multi-spacecraft measurements,
  indicating that modeled FDs reflect well the CME evolution.

---------------------------------------------------------
Title: A statistical study of the long-term evolution of coronal
    hole properties as observed by SDO
Authors: Heinemann, S. G.; Jerčić, V.; Temmer, M.; Hofmeister,
   S. J.; Dumbović, M.; Vennerstrom, S.; Verbanac, G.; Veronig, A. M.
2020A&A...638A..68H    Altcode: 2019arXiv190702795H; 2019arXiv190702795J
  Context. Understanding the evolution of coronal holes is especially
  important when studying the high-speed solar wind streams that emanate
  from them. Slow- and high-speed stream interaction regions may deliver
  large amounts of energy into the Earth's magnetosphere-ionosphere
  system, cause geomagnetic storms, and shape interplanetary space. <BR
  /> Aims: By statistically investigating the long-term evolution of
  well-observed coronal holes we aim to reveal processes that drive
  the observed changes in the coronal hole parameters. By analyzing 16
  long-living coronal holes observed by the Solar Dynamic Observatory,
  we focus on coronal, morphological, and underlying photospheric magnetic
  field characteristics, and investigate the evolution of the associated
  high-speed streams. <BR /> Methods: We use the Collection of Analysis
  Tools for Coronal Holes to extract and analyze coronal holes using
  193 Å EUV observations taken by the Atmospheric Imaging Assembly as
  well as line-of-sight magnetograms observed by the Helioseismic and
  Magnetic Imager. We derive changes in the coronal hole properties and
  look for correlations with coronal hole evolution. Further, we analyze
  the properties of the high-speed stream signatures near 1AU from OMNI
  data by manually extracting the peak bulk velocity of the solar wind
  plasma. <BR /> Results: We find that the area evolution of coronal
  holes shows a general trend of growing to a maximum followed by a
  decay. We did not find any correlation between the area evolution
  and the evolution of the signed magnetic flux or signed magnetic
  flux density enclosed in the projected coronal hole area. From this
  we conclude that the magnetic flux within the extracted coronal
  hole boundaries is not the main cause for its area evolution. We
  derive coronal hole area change rates (growth and decay) of (14.2
  ± 15.0)×10<SUP>8</SUP> km<SUP>2</SUP> per day showing a reasonable
  anti-correlation (cc<SUB>Pearson</SUB> = -0.48) to the solar activity,
  approximated by the sunspot number. The change rates of the signed mean
  magnetic flux density (27.3 ± 32.2 mG day<SUP>-1</SUP>) and the signed
  magnetic flux (30.3 ± 31.5 10<SUP>18</SUP> Mx day<SUP>-1</SUP>) were
  also found to be dependent on solar activity (cc<SUB>Pearson</SUB> =
  0.50 and cc<SUB>Pearson</SUB> = 0.69 respectively) rather than on the
  individual coronal hole evolutions. Further we find that the relation
  between coronal hole area and high-speed stream peak velocity is
  valid for each coronal hole over its evolution, but we see significant
  variations in the slopes of the regression lines.

---------------------------------------------------------
Title: Prediction of CME arrivals; differences based on stereoscopic
    heliospheric imager data
Authors: Hinterreiter, Jürgen; Amerstorfer, Tanja; Reiss, Martin A.;
   Temmer, Manuela; Möstl, Christian; Bauer, Maike; Amerstorfer, Ute V.;
   Bailey, Rachel L.; Weiss, Andreas J.
2020EGUGA..22.7829H    Altcode:
  Forecasting the arrival time and speed of CMEs is of high
  importance. However, uncertainties in the forecasts are high. We present
  the results of post-event prediction of CME arrivals using ELEvoHI
  (ELlipse Evolution model based on Heliospheric Imager observations)
  ensemble modeling. The model uses time-elongation profiles provided by
  HI (Heliospheric Imager) onboard STEREO (Solar TErrestrial RElations
  Observatory) and assumes an elliptical shape of the CME front. The
  drag force exerted by the ambient solar wind is an essential factor
  influencing the dynamic evolution of CMEs in the heliosphere. To
  account for this effect, ELEvoHI utilizes the modeled ambient solar
  wind provided by the Wang-Sheeley-Arge model. We carefully select 12
  CMEs between February 2010 and July 2012, which show clear signatures
  in STEREO-A and STEREO-B HI images, have a corresponding in-situ
  signature, and propagate close to the ecliptic plane. As input to
  ELEvoHI, we make use of STEREO-A and STEREO-B time-elongation profiles
  for each CME and compare the predicted arrival times and speeds based
  on both vantage points with each other. We present our model results
  and discuss possible reasons for the differences in the arrival times
  of up to 15 hours.

---------------------------------------------------------
Title: Magnetic Flux Emergence in a Coronal Hole
Authors: Palacios, Judith; Utz, Dominik; Hofmeister, Stefan; Krikova,
   Kilian; Gömöry, Peter; Kuckein, Christoph; Denker, Carsten; Verma,
   Meetu; González Manrique, Sergio Javier; Campos Rozo, Jose Iván;
   Koza, Július; Temmer, Manuela; Veronig, Astrid; Diercke, Andrea;
   Kontogiannis, Ioannis; Cid, Consuelo
2020SoPh..295...64P    Altcode: 2020arXiv200611779P
  A joint campaign of various space-borne and ground-based observatories,
  comprising the Japanese Hinode mission (Hinode Observing Plan 338,
  20 - 30 September 2017), the GREGOR solar telescope, and the Vacuum
  Tower Telescope (VTT), investigated numerous targets such as pores,
  sunspots, and coronal holes. In this study, we focus on the coronal
  hole region target. On 24 September 2017, a very extended non-polar
  coronal hole developed patches of flux emergence, which contributed
  to the decrease of the overall area of the coronal hole. These flux
  emergence patches erode the coronal hole and transform the area into a
  more quiet-Sun-like area, whereby bipolar magnetic structures play an
  important role. Conversely, flux cancellation leads to the reduction
  of opposite-polarity magnetic fields and to an increase in the area
  of the coronal hole.

---------------------------------------------------------
Title: Using Forbush decreases at Earth and Mars to measure the
    radial evolution of ICMEs
Authors: von Forstner, Johan; Guo, Jingnan; Wimmer-Schweingruber,
   Robert F.; Dumbović, Mateja; Janvier, Miho; Démoulin, Pascal;
   Veronig, Astrid; Temmer, Manuela; Papaioannou, Athanasios; Dasso,
   Sergio; Hassler, Donald M.; Zeitlin, Cary J.
2020EGUGA..22.7838V    Altcode:
  Interplanetary coronal mass ejections (ICMEs), large clouds of plasma
  and magnetic field regularly expelled from the Sun, are one of the
  main drivers of space weather effects in the solar system. While
  the prediction of their arrival time at Earth and other locations
  in the heliosphere is still a complex task, it is also necessary to
  further understand the time evolution of their geometric and magnetic
  structure, which is even more challenging considering the limited number
  of available observation points.Forbush decreases (FDs), short-term
  drops in the flux of galactic cosmic rays (GCR), can be caused by the
  shielding from strong and/or turbulent magnetic structures in the solar
  wind, such as ICMEs and their associated shock/sheath regions. In the
  past, FD observations have often been used to determine the arrival
  times of ICMEs at different locations in the solar system, especially
  where sufficient solar wind plasma and magnetic field measurements are
  not (or not always) available. One of these locations is Mars, where the
  Radiation Assessment Detector (RAD) onboard the Mars Science Laboratory
  (MSL) mission's Curiosity rover has been continuously measuring GCRs and
  FDs on the surface for more than 7 years.In this work, we investigate
  whether FD data can be used to derive additional information about the
  ICME properties than just the arrival time by performing a statistical
  study based on catalogs of FDs observed at Earth or Mars. In particular,
  we find that the linear correlation between the FD amplitude and the
  maximum steepness, which was already seen at Earth by previous authors
  (Belov et al., 2008, Abunin et al., 2012), is likewise present at Mars,
  but with a different proprtionality factor.By consulting physics-based
  analytical models of FDs, we find that this quantity is not expected to
  be influenced by the different energy ranges of GCR particles observed
  by the instruments at Earth and Mars. Instead, we suggest that the
  difference in FD characteristics at the two planets is caused by the
  radial enlargement of the ICMEs, and particularly their sheath regions,
  as they propagate from Earth (1 AU) to Mars (~ 1.5 AU). This broadening
  factor derived from our analysis extends observations for the evolution
  closer to the Sun by Janvier et al. (2019, JGR Space Physics) to larger
  heliocentric distances and is consistent with these results.

---------------------------------------------------------
Title: Analysis of a severe geomagnetic storm on August 26, 2018
    and the related effects on the GRACE-FO mission
Authors: Krauss, Sandro; Temmer, Manuela; Behzadpour, Saniya; Lhotka,
   Christoph
2020EGUGA..22.3499K    Altcode:
  On August 20, 2018 a complex interplanetary coronal mass ejections
  (ICME) occurred on the Sun, which subsequently triggered an unexpected
  large geomagnetic storm on August 25. We present a detailed analysis of
  the ICME eruption and explore the occurred perturbation of the neutral
  mass density in the upper Earth's atmosphere. The analysis is based on
  accelerometer observations from the satellite mission GRACE Follow-On as
  well as interplanetary magnetic field measurements by the DSCOVR and ACE
  spacecraft. Through the evaluation of solar observations by the SECCHI
  instrument on-board of the STEREO-A satellite in form of white-light,
  the early evolution of the ICME can be aptly illustrated. Furthermore,
  due to the heating and the subsequent expansion of the thermosphere
  also the drag force acting on the spacecraft is enhanced. This leads
  to an additional storm induced orbit decay, which we calculate by
  means of variations in the semi-major axis. The findings are compared
  with predictions from our preliminary thermospheric forecasting tool,
  which is based on the study by Krauss et al. 2018.

---------------------------------------------------------
Title: Understanding our capabilities in observing and modelling
    Coronal Mass Ejections
Authors: Verbeke, Christine; Mierla, Marilena; Mays, M. Leila;
   Kay, Christina; Dumbovic, Mateja; Temmer, Manuela; Palmerio, Erika;
   Paouris, Evangelos; Cremades, Hebe; Riley, Pete; Scolini, Camilla;
   Hinterreiter, Juergen
2020EGUGA..2220456V    Altcode:
  Coronal Mass Ejections (CMEs) are large-scale eruptions of plasma and
  magnetic fields from the Sun. They are considered to be the main drivers
  of strong space weather events at Earth. Multiple models have been
  developed over the past decades to be able to predict the propagation
  of CMEs and their arrival time at Earth. Such models require input
  from observations, which can be used to fit the CME to an appropriate
  structure.When determining input parameters for CME propagation
  models, it is common procedure to derive kinematic parameters from
  remote-sensing data. The resulting parameters can be used as inputs for
  the CME propagation models to obtain an arrival prediction time of the
  CME f.e. at Earth. However, when fitting the CME structure to obtain the
  needed parameters for simulations, different geometric structures and
  also different parts of the CME structure can be fitted. These aspects,
  together with the fact that 3D reconstructions strongly depend on the
  subjectivity and judgement of the scientist performing them, may lead
  to uncertainties in the fitted parameters. Up to now, no large study
  has tried to map these uncertainties and to evaluate how they affect
  the modelling of CMEs. Fitting a large set of CMEs within a selected
  period of time, we aim to investigate the uncertainties in the CME
  fittings in detail. Each event is fitted multiple times by different
  scientists. We discuss statistics on uncertainties of the fittings. We
  also present some first results of the impact of these uncertainties
  on CME propagation modelling.Acknowledgements: This work has been
  partly supported by the International Space Science Institute (ISSI)
  in the framework of International Team 480 entitled: Understanding
  Our Capabilities In Observing And Modelling Coronal Mass Ejections'.

---------------------------------------------------------
Title: Observation-based modelling of magnetised CMEs in the inner
    heliosphere with EUHFORIA
Authors: Scolini, Camilla; Pomoell, Jens; Chané, Emmanuel; Poedts,
   Stefaan; Rodriguez, Luciano; Kilpua, Emilia; Temmer, Manuela;
   Verbeke, Christine; Dissauer, Karin; Veronig, Astrid; Palmerio, Erika;
   Dumbović, Mateja
2020EGUGA..22.1777S    Altcode:
  Coronal Mass Ejections (CMEs) are the primary source of strong
  space weather disturbances at Earth and other locations in the
  heliosphere. Understanding the physical processes involved in their
  formation at the Sun, propagation in the heliosphere, and impact
  on planetary bodies is therefore critical to improve current space
  weather predictions throughout the heliosphere. The capability of CMEs
  to drive strong space weather disturbances at Earth and other planetary
  and spacecraft locations primarily depends on their dynamic pressure,
  internal magnetic field strength, and magnetic field orientation at
  the impact location. In addition, phenomena such as the interaction
  with the solar wind and other solar transients along the way, or
  the pre-conditioning of interplanetary space due to the passage of
  previous CMEs, can significantly modify the properties of individual
  CMEs and alter their ultimate space weather impact. Investigating
  and modeling such phenomena via advanced physics-based heliospheric
  models is therefore crucial to improve the space weather prediction
  capabilities in relation to both single and complex CME events. In this
  talk, we present our progress in developing novel methods to model CMEs
  in the inner heliosphere using the EUHFORIA MHD model in combination
  with remote-sensing solar observations. We discuss the various
  observational techniques that can be used to constrain the initial
  CME parameters for EUHFORIA simulations. We present current efforts
  in developing more realistic magnetised CME models aimed at describing
  their internal magnetic structure in a more realistic fashion. We show
  how the combination of these two approaches allows the investigation of
  CME propagation and evolution throughout the heliosphere to a higher
  level of detail, and results in significantly improved predictions of
  CME impact at Earth and other locations in the heliosphere. Finally,
  we discuss current limitations and future improvements in the context
  of studying space weather events throughout the heliosphere.

---------------------------------------------------------
Title: The impact of coronal hole characteristics and solar cycle
    activity in reconstructing coronal holes with EUHFORIA
Authors: Asvestari, E.; Heinemann, S. G.; Temmer, M.; Pomoell, J.;
   Kilpua, E.; Magdalenic, J.; Poedts, S.
2020JPhCS1548a2004A    Altcode:
  Modelling with high accuracy the open magnetic field and the fast solar
  wind in the heliosphere is essential for space weather forecasting
  purposes. Primary sources of open magnetic field flux are Coronal
  Holes (CH), uni-polar regions that appear as dark patches in the
  solar corona when observed in X-ray and extreme-ultraviolet (EUV)
  images due to having significantly lower density and temperature
  to their surroundings. Therefore, when assessing how well the open
  magnetic field and the fast solar wind are modelled one can look at
  how well the model performs on one of its fundamental functions, that
  of reconstructing coronal hole areas. In this study we investigate how
  the CH morphology (i.e. latitudinal position of the centre of mass,
  area, intensity, elongation) and the solar variability, from high to
  low activity periods, can affect the results. We also investigated the
  possibility that the model is reconstructing CHs that are systematically
  shifted with respect to their observed position. The study is applied
  on 15 CHs exhibiting different latitudinal position and geometry. We
  compare the modelled CH areas with boundaries obtained by remote sensing
  EUV observations using the CATCH tool (Collection of Analysis Tools for
  Coronal Holes). We found no apparent effect of the CH characteristics
  on the modelling capabilities. In addition, solar cycle activity seems
  not to have any effect either. However, we emphasize that our sample
  is small and this outcome highlights the need for an extended research.

---------------------------------------------------------
Title: CME evolution and the corresponding Forbush decrease: modelling
    vs multi-spacecraft observation
Authors: Dumbovic, Mateja; Vrsnak, Bojan; Guo, Jingnan; Heber, Bernd;
   Dissauer, Karin; Carcaboso-Morales, Fernando; Temmer, Manuela; Veronig,
   Astrid; Podladchikova, Tatiana; Möstl, Christian; Amerstorfer, Tanja;
   Kirin, Anamarija
2020EGUGA..2210446D    Altcode:
  One of the very common in-situ signatures of ICMEs, as well as other
  interplanetary transients are Forbush decreases (FDs), i.e. short-term
  reductions in the galactic cosmic ray (GCR) flux. A two-step FD is
  often regarded as a textbook example, which presumably owns its specific
  morphology to the fact that the measuring instrument passed through the
  ICME head-on, encountering first the shock front (if developed), then
  the sheath and finally the magnetic structure. The interaction of GCRs
  and the shock/sheath region as well as CME magnetic structure occurs all
  the way from Sun to Earth, therefore, FDs are expected to reflect the
  evolutionary properties of CMEs and their sheaths. We apply modelling
  to different ICME regions in order to obtain a generic two-step FD
  profile, which qualitatively agrees with our current observation-based
  understanding of FDs. We next adapt the models for energy dependence
  to enable comparison with different GCR measurement instruments
  (as they measure in different particle energy ranges). We test these
  modelling efforts against a set of multi-spacecraft observations of
  the same event.

---------------------------------------------------------
Title: Exploring Thermospheric Variations Triggered by Severe
    Geomagnetic Storm on 26 August 2018 Using GRACE Follow-On Data
Authors: Krauss, S.; Behzadpour, S.; Temmer, M.; Lhotka, C.
2020JGRA..12527731K    Altcode:
  With the successful launch of the satellite mission Gravity Recovery
  and Climate Experiment (GRACE) Follow-On in May 2018 the opportunity
  arises to resume the analysis of accelerometer data regarding space
  weather induced perturbations of the Earth's thermosphere. On
  21 August 2018 a complex interplanetary coronal mass ejections
  occurred on the Sun, which subsequently triggered an unexpected
  large geomagnetic storm on 26 August. We present a detailed analysis
  of the interplanetary coronal mass ejection eruption and explore
  the occurred perturbation of the neutral mass density in the upper
  Earth's atmosphere. Due to the heating and the subsequent expansion
  of the thermosphere also the drag force acting on the spacecraft
  is enhanced. This leads to an additional storm-induced orbit
  decay, which we calculate by means of variations in the semimajor
  axis. The evaluation is based on the utilization of accelerometer
  measurements from GRACE Follow-On. For the reduction of disturbing
  nongravitational forces we implemented a physical shadow function,
  which incorporates the Earth's oblateness and the atmospheric refraction
  and extinction. Additionally, the estimation of Earth's reradiation
  is now based on hourly measurements by the Clouds and the Earth's
  Radiant Energy System. The resulting atmospheric densities and orbit
  decays are compared with predictions from our preliminary thermospheric
  forecasting tool, which is based on the study by Krauss et al. (2018, <A
  href="https://doi.org/10.1029/2018JA025778">https://doi.org/10.1029/2018JA025778</A>).
  The evaluation shows that the maximum estimated orbit decay triggered
  by the geomagnetic storm on 26 August is in the order of approximately
  8.2 m and thus in good accordance with the forecasted value (9.5
  m)—predicted with a lead time of about 60 min.

---------------------------------------------------------
Title: Relating CME density derived from remote sensing data to CME
    sheath solar wind plasma pile up as measured in-situ
Authors: Temmer, Manuela; Holzknecht, Lukas; Dumbovic, Mateja; Vrsnak,
   Bojan; Sachdeva, Nishtha; Heinemann, Stephan; Dissauer, Karin; Scolini,
   Camilla; Asvestari, Eleanna; Veronig, Astrid; Hofmeister, Stefan
2020EGUGA..22.3341T    Altcode:
  For better estimating the drag force acting on coronal mass ejections
  (CMEs) in interplanetary space and ram-pressure at planets, improved
  knowledge of the evolution of CME density/mass is highly valuable. We
  investigate a sample of 29 well observed CME-ICME events, for which
  we determine the de-projected 3D mass (STEREO-A and -B data), and the
  CME volume using GCS modeling (STEREO, SoHO). Expanding the volume to
  1AU distance, we derive the density and compare the results to in-situ
  proton density measurements separately for the ICME sheath and magnetic
  structure. A fair agreement between calculated and measured density is
  derived for the magnetic structure as well for the sheath if taking
  into account mass pile up of solar wind plasma. We give evidence and
  observational assessment that during the interplanetary propagation
  of a CME 1) the magnetic structure has rather constant mass and 2)
  the sheath region at the front of the driver is formed from piled-up
  mass that is rather depending on the solar wind density ahead of the
  CME, than on the CME speed.

---------------------------------------------------------
Title: Comparing the Properties of ICME-Induced Forbush Decreases
    at Earth and Mars
Authors: Freiherr von Forstner, Johan L.; Guo, Jingnan;
   Wimmer-Schweingruber, Robert F.; Dumbović, Mateja; Janvier, Miho;
   Démoulin, Pascal; Veronig, Astrid; Temmer, Manuela; Papaioannou,
   Athanasios; Dasso, Sergio; Hassler, Donald M.; Zeitlin, Cary J.
2020JGRA..12527662F    Altcode: 2020arXiv200303157V
  Forbush decreases (FDs), which are short-term drops in the flux
  of galactic cosmic rays, are caused by the shielding from strong
  and/or turbulent magnetic structures in the solar wind, especially
  interplanetary coronal mass ejections (ICMEs) and their associated
  shocks, as well as corotating interaction regions. Such events can be
  observed at Earth, for example, using neutron monitors, and also at
  many other locations in the solar system, such as on the surface of
  Mars with the Radiation Assessment Detector instrument onboard Mars
  Science Laboratory. They are often used as a proxy for detecting the
  arrival of ICMEs or corotating interaction regions, especially when
  sufficient in situ solar wind measurements are not available. We
  compare the properties of FDs observed at Earth and Mars, focusing
  on events produced by ICMEs. We find that FDs at both locations show
  a correlation between their total amplitude and the maximum hourly
  decrease, but with different proportionality factors. We explain this
  difference using theoretical modeling approaches and suggest that it is
  related to the size increase of ICMEs, and in particular their sheath
  regions, en route from Earth to Mars. From the FD data, we can derive
  the sheath broadening factor to be between about 1.5 and 1.9, agreeing
  with our theoretical considerations. This factor is also in line with
  previous measurements of the sheath evolution closer to the Sun.

---------------------------------------------------------
Title: CME-CME Interactions as Sources of CME Geoeffectiveness:
    The Formation of the Complex Ejecta and Intense Geomagnetic Storm
    in 2017 Early September
Authors: Scolini, Camilla; Chané, Emmanuel; Temmer, Manuela; Kilpua,
   Emilia K. J.; Dissauer, Karin; Veronig, Astrid M.; Palmerio, Erika;
   Pomoell, Jens; Dumbović, Mateja; Guo, Jingnan; Rodriguez, Luciano;
   Poedts, Stefaan
2020ApJS..247...21S    Altcode: 2019arXiv191110817S
  Coronal mass ejections (CMEs) are the primary sources of intense
  disturbances at Earth, where their geoeffectiveness is largely
  determined by their dynamic pressure and internal magnetic field,
  which can be significantly altered during interactions with other
  CMEs in interplanetary space. We analyze three successive CMEs that
  erupted from the Sun during 2017 September 4-6, investigating the
  role of CME-CME interactions as a source of the associated intense
  geomagnetic storm (Dst_{min}=-142 nT on September 7). To quantify
  the impact of interactions on the (geo)effectiveness of individual
  CMEs, we perform global heliospheric simulations with the European
  Heliospheric Forecasting Information Asset (EUHFORIA) model, using
  observation-based initial parameters with the additional purpose of
  validating the predictive capabilities of the model for complex CME
  events. The simulations show that around 0.45 au, the shock driven by
  the September 6 CME started compressing a preceding magnetic ejecta
  formed by the merging of two CMEs launched on September 4, significantly
  amplifying its B<SUB>z</SUB> until a maximum factor of 2.8 around 0.9
  au. The following gradual conversion of magnetic energy into kinetic
  and thermal components reduced the B<SUB>z</SUB> amplification until
  its almost complete disappearance around 1.8 au. We conclude that a
  key factor at the origin of the intense storm triggered by the 2017
  September 4-6 CMEs was their arrival at Earth during the phase of
  maximum B<SUB>z</SUB> amplification. Our analysis highlights how the
  amplification of the magnetic field of individual CMEs in spacetime due
  to interaction processes can be characterized by a growth, a maximum,
  and a decay phase, suggesting that the time interval between the CME
  eruptions and their relative speeds are critical factors in determining
  the resulting impact of complex CMEs at various heliocentric distances
  (helioeffectiveness).

---------------------------------------------------------
Title: Differential Emission Measure Plasma Diagnostics of a
    Long-Lived Coronal Hole
Authors: Saqri, Jonas; Veronig, Astrid M.; Heinemann, Stephan G.;
   Hofmeister, Stefan J.; Temmer, Manuela; Dissauer, Karin; Su, Yang
2020SoPh..295....6S    Altcode: 2020arXiv200102259S
  We use Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly
  (AIA) data to reconstruct the plasma properties from differential
  emission measure (DEM) analysis for a previously studied long-lived,
  low-latitude coronal hole (CH) over its lifetime of ten solar
  rotations. We initially obtain a non-isothermal DEM distribution with
  a dominant component centered around 0.9 MK and a secondary smaller
  component at 1.5 - 2.0 MK. We find that deconvolving the data with
  the instrument point spread function (PSF) to account for long-range
  scattered light reduces the secondary hot component. Using the 2012
  Venus transit and a 2013 lunar eclipse to test the efficiency of this
  deconvolution, significant amounts of residual stray light are found
  for the occulted areas. Accounting for this stray light in the error
  budget of the different AIA filters further reduces the secondary hot
  emission, yielding CH DEM distributions that are close to isothermal
  with the main contribution centered around 0.9 MK. Based on these DEMs,
  we analyze the evolution of the emission measure (EM), density, and
  averaged temperature during the CH's lifetime. We find that once the CH
  is clearly observed in EUV images, the bulk of the CH plasma reveals
  a quite constant state, i.e. temperature and density reveal no major
  changes, whereas the total CH area and the photospheric magnetic fine
  structure inside the CH show a distinct evolutionary pattern. These
  findings suggest that CH plasma properties are mostly "set" at the CH
  formation or/and that all CHs have similar plasma properties.

---------------------------------------------------------
Title: Comparing the Properties of ICME-Induced Forbush Decreases
    at Earth and Mars
Authors: Freiherr von Forstner, J. L.; Guo, J.; Wimmer-Schweingruber,
   R. F.; Dumbovic, M.; Janvier, M.; Demoulin, P.; Veronig, A.; Temmer,
   M.; Hassler, D.; Zeitlin, C.
2019AGUFMSH41D3339F    Altcode:
  Forbush decreases (FDs), short-term drops in the flux of galactic
  cosmic rays (GCR), can be caused by the shielding from strong and/or
  turbulent magnetic structures in the solar wind, i.e. interplanetary
  coronal mass ejections (ICMEs) and their associated shocks as well
  as corotating interaction regions (CIRs). FDs are often used as a
  proxy for detecting the arrival of ICMEs or CIRs at locations where
  sufficient in situ solar wind measurements are not or not always
  available, such as at Mars. The Radiation Assessment Detector (RAD)
  onboard the Mars Science Laboratory (MSL) mission's Curiosity rover
  has been continuously measuring the GCR environment on the surface
  of Mars for more than 7 years since its landing in August 2012 and is
  thus an excellent source for measurements of FDs at Mars (see e.g. <A
  href="https://doi.org/10.1051/0004-6361/201732087">Guo et al. 2018,
  A&amp;A</A>). <P />Based on the large catalog of FDs at Mars compiled
  by <A href="https://doi.org/10.1007/s11207-019-1454-2">Papaioannou et
  al. (2019, Solar Physics)</A> as well as results from our previous
  work (<A href="https://doi.org/10.1029/2018SW002138">Freiherr von
  Forstner et al., 2019, Space Weather</A>), we study the parameters
  of FDs at Mars and their relations, focusing on events produced by
  ICMEs. We then compare these data with catalogs of terrestrial FDs,
  investigating whether and to what extent the differences of certain FD
  characteristics between the two planets, at two different heliospheric
  distances, are related to the evolution of ICMEs between Earth and
  Mars. <P />Our results show that there is a linear correlation between
  the FD amplitude (drop percentage) and the maximum hourly GCR decrease
  during the FD, which was already found at Earth by previous authors (<A
  href="https://doi.org/10.1017/S1743921309029676">Belov et al., 2008</A>,
  <A href="https://doi.org/10.1134/S0016793212030024">Abunin et al.,
  2012</A>). However, this correlation has a different proprtionality
  factor at Mars than at Earth, especially for ICME-induced events. As
  we do not find a clear dependence of this relationship on the observed
  GCR energy range, we suggest that this difference is probably caused by
  the expansion of the ICME sheath region as it propagates outward from
  1 AU to ∼1.5 AU. The expansion factor derived from our analysis is in
  line with expansion factors of ICME sheaths within the inner heliosphere
  observed by &lt;a href="https://doi.org/10.1029/2018JA025949&gt;Janvier
  et al. (2019, JGR Space Physics).

---------------------------------------------------------
Title: A study of the role of CME-CME interactions on CME
    geo-effectiveness with EUHFORIA
Authors: Scolini, C.; Poedts, S.; Rodriguez, L.; Temmer, M.; Dumbovic,
   M.; Guo, J.; Veronig, A.; Dissauer, K.; Palmerio, E.; Kilpua, K. E. J.;
   Pomoell, J.
2019AGUFMSH43D3368S    Altcode:
  Coronal Mass Ejections (CMEs) are the main source of strong space
  weather disturbances at Earth and other locations in the solar
  system. While their impact is largely determined by their dynamic
  pressure and magnetic field, interactions with other CMEs can
  significantly alter their individual characteristics and enhance their
  (geo-)effectiveness. As observations in the heliosphere are limited,
  investigating such phenomena via physics-based models is therefore
  crucial to advance our understanding of complex CME events, and to
  assess the prediction capabilities at various locations. <P />Here we
  present a comprehensive study of the role of CME-CME interactions on
  their (geo-)effectiveness, by performing simulations of complex CME
  events with the EUHFORIA heliospheric solar wind and CME propagation
  model. As a case study, we consider a sequence of 6 CMEs observed during
  the unusually active week of 4-10 September 2017. As their source region
  moved on the solar disk due to the rotation, CMEs were launched over
  a wide range of longitudes, interacting with each other while paving
  the way for the propagation of the following ones. CME signatures were
  observed at Mars and at Earth, where intense disturbances and space
  weather events were triggered by CME-CME interactions. Using input
  parameters derived from multi-spacecraft remote-sensing observations
  of CMEs and their source region, we perform global simulations of the
  event using the spheromak CME model in EUHFORIA, and we investigate how
  their interactions affected the evolution of single CME structures and
  the in-situ properties at Earth and Mars. <P />Results from this case
  study are complemented by a parametric study of CME-CME interactions,
  performed by running a set of simulations varying the initial CME
  parameters (e.g. speed, waiting time, magnetic field properties,
  density…), with the aim of quantifying the effect of such changes on
  their propagation and interaction. Results will benchmark our current
  prediction capabilities in the case of complex CME events and provide
  insights on their large-scale evolution in the heliosphere.

---------------------------------------------------------
Title: Improving Modelling Areas of Open-Closed Flux in the Corona
    Using Remote Sensing Observations
Authors: Asvestari, E.; Heinemann, S.; Temmer, M.; Pomoell, J.;
   Kilpua, K. E. J.; Magdalenic, J.; Poedts, S.
2019AGUFMSH13A..09A    Altcode:
  Modelling the open magnetic field in the heliosphere with high
  accuracy is essential for space weather forecasting purposes. Primary
  source of open magnetic field are Coronal Holes (CH). Therefore, when
  assessing how well we model the open magnetic field one needs to test
  how well the model performs on one of its fundamental functions, that
  of reconstructing coronal hole areas. For our study, we used EUHFORIA
  (European heliospheric forecasting information asset) model which
  employs an empirical solar wind model that combines the Potential
  Field Source Surface (PFSS) and the Schatten Current Sheet (SCS)
  models. Two important free parameters of the PFSS and the SCS models
  are the source surface height (the outer boundary of the PFSS) and the
  height of the inner boundary of SCS. Although, a commonly used value
  for the source surface height is that of 2.5 solar radii, a wider range
  of allowed heights ranging from 1.5 to 3.25 solar radii exist. Here, we
  investigate the optimal heights that one should preselect in the model
  aiming for better reconstruction of open flux areas. We vary the source
  surface height within the interval [1.4, 3.2]Rs with a step of 0.1Rs,
  and the SCS inner boundary height within the interval [1.3, 2.8]Rs with
  the same step, where Rs is one solar radius. The study is applied on 15
  CH exhibiting different latitudinal position and geometry. We compare
  the modelled open flux areas with CH boundaries extracted using remote
  sensing EUV observations and CATCH (Collection of analysis tools for
  coronal holes). This study indicates that lower values of the two
  boundary heights improve the modelling results. EUV image data from
  instruments having a wide field of view, such as SUVI on board GOES-R,
  and SWAP on board PROBA2, offer unprecedented possibility to actually
  observe the heights below which closed loops exist in the corona,
  and therefore further constrain the height choices in the model by
  providing a lower limit.

---------------------------------------------------------
Title: Genesis and impulsive evolution of the fast CME associated
    with the X8.2 flare on 2017 September 10
Authors: Veronig, A.; Podladchikova, T.; Dissauer, K.; Temmer, M.;
   Seaton, D. B.; Long, D.; Guo, J.; Vrsnak, B.; Harra, L. K.; Kliem, B.
2019AGUFMSH13A..02V    Altcode:
  The X8.2 event of 2017 September 10 provides unique observations to
  study the genesis, magnetic morphology, impulsive dynamics and shock
  formation in a very fast coronal mass ejection (CME). As will be
  discussed in this presentation, fundamental insight in the processes
  of magnetic reconnection, CME acceleration and shock formation are
  provided through EUV observations of the middle corona. <P />Combining
  the large field-of-view and high-cadence imagery from GOES-16/SUVI
  and SDO/AIA EUV, respectively, we identify a hot (T ≈ 10-15 MK)
  bright rim around a quickly expanding cavity, embedded inside a much
  larger CME shell (T ≈ 1-2 MK). The CME shell develops from a dense
  set of large AR loops (&gt;0.5Rs) and seamlessly evolves into the
  CME front observed in LASCO C2. The strong lateral overexpansion
  of the CME shell acts as a piston initiating the fast and globally
  propagating EUV shock wave. The hot cavity rim is demonstrated to be
  a manifestation of the dominantly poloidal flux and frozen-in plasma
  added to the rising flux rope by magnetic reconnection in the current
  sheet beneath. The same structure is later observed as the core of the
  white-light CME, challenging the traditional interpretation of the CME
  three-part morphology (Veronig et al. 2018). <P />The large amount of
  added magnetic flux suggested by these observations can explain the
  extreme accelerations of the radial and lateral expansion of the CME
  shell and cavity, all reaching values up to 5-10 km s<SUP>-2</SUP>. The
  acceleration peaks occur simultaneously with the first RHESSI 100-300
  keV hard X-ray burst of the associated flare, further underlining the
  importance of the reconnection process for the impulsive CME evolution
  in the low and middle corona.

---------------------------------------------------------
Title: International Scientific Coordination on Space Weather:
    A COSPAR Panel on Space Weather Perspective
Authors: Bisi, M. M.; Kuznetsova, M. M.; Temmer, M.; Opgenoorth, H. J.;
   Belehaki, A.; Bruinsma, S.; Glover, A.; Heynderickx, D.; Linker, J.;
   Mann, I. R.; Murray, S. A.; Nandy, D.
2019AGUFMSM31C3543B    Altcode:
  The understanding and prediction of space-weather phenomena and
  their respective impact(s) on society have been widely-acknowledged
  as an international challenge and something that requires a global
  coordination and focus. In order to address this need to form
  more-formal worldwide collaboration and coordination, and to maximise
  return on such efforts (particularly scientifically), the Committee
  on Space Research (COSPAR) Panel on Space Weather (PSW) has created a
  network of International Space Weather Action Teams (ISWATs). <P />The
  COSPAR PSW ISWAT initiative is capitalising on established efforts by
  engaging existing national and international "teams" and "facilitates"
  to form individual ISWATs that are being grouped into clusters
  by domains/themes related to different aspects of solar/coronal,
  heliospheric, ionospheric/atmospheric, and planetary space-weather
  phenomena. The initiative also includes overarching themes such as
  dealing with large data sets and model/scientific validations. The
  ISWAT initiative places a strong encouragement for scientists to go
  beyond their funding borders to form ISWATs better suited to address
  challenges that one individual or small group/team may not be able to
  address alone. <P />The ISWAT initiative serves as a global hub for
  community coordinated topical focused collaborations and as a global
  community voice for the next generation of both scientific and strategic
  planning - this includes an update of the COSPAR/ILWS space weather
  scientific roadmap (to transform the roadmap into a living document)
  and to potentially provide an operational roadmap in parallel. <P
  />This presentation will re-introduce the ISWAT initiative, review
  its current status and plans for community-wide campaigns, highlight
  the overarching current plans for PSW, and place a focus on two key
  space-weather areas: the ambient heliosphere/background solar wind
  (designated as ISWAT theme H1) and CME structure, evolution and
  propagation through heliosphere (designated as ISWAT theme H2).

---------------------------------------------------------
Title: Showcasing the just released ISWAT website
(http://www.iswat-cospar.org) built with a content management platform
    to serve as an online presence for the ISWAT (International Space
    Weather Action Teams) - community driven effort hosted by the COSPAR
    Panel on Space Weather.
Authors: Mendoza, A. M. M.; Kuznetsova, M.; Opgenoorth, H. J.;
   Belehaki, A.; Bisi, M. M.; Bruinsma, S.; Heynderickx, D.; Linker,
   J.; Mann, I. R.; Murray, S. A.; Nandy, D.; Temmer, M.
2019AGUFMSM31C3181M    Altcode:
  We will showcase the just released ISWAT website (<A
  href="http://www.iswat-cospar.org/">http://www.iswat-cospar.org</A>)
  built with a content management platform to serve as an online
  presence for the <P />ISWAT (International Space Weather Action
  Teams) - community driven effort hosted by the COSPAR Panel on Space
  Weather. <P />The website was created to represent ISWAT overarching
  goal to serve as a global hub for topical collaborations and focused
  on different aspects of space weather. <P />The homepage main's ISWAT
  image menu shows ISWAT clusters that cover Solar (S), Heliosphere
  (H) and Geospace (G) domains. Each cluster (S1-S3, H1-H4, G1-G3)
  <P />shown in the image is links to dedicated webpages that contain
  information about cluster goals and links to entry pages of registered
  action teams. <P />The "Join ISWAT" link contains 2 interactive forms
  for joining ISWAT mailing list and for registration of established and
  emerging international teams focused on different <P />aspects of space
  weather. After the registration is confirmed by cluster moderator a link
  to a new team entry page is added to a submitted cluster site. A team
  start entry <P />team page will contain information submitted during
  registration that may include a link to an external team page as an
  option. Another interactive form to join a <P />registered ISWAT team
  will be added in the near future. <P />Future planned additions include
  a Forum to create threaded discussion boards to encourage discussions
  on global coordination of space weather and invite community inputs
  to global space weather roadmap updates. <P />The website will be
  eventually maintained and facilitated by the COSPAR Panel on Space
  Weather Chairs/Vice-chairs, ISWAT cluster moderators, and ISWAT team
  <P />representatives.

---------------------------------------------------------
Title: International Scientific Coordination on Space Weather:
    A COSPAR Panel on Space Weather Perspective
Authors: Kuznetsova, M.; Bisi, M. M.; Kusano, K.; Fuller-Rowell,
   T. J.; Mann, I.; Belehaki, A.; Minow, J. I.; Munoz-Jaramillo, A.;
   Masson, A.; Bruinsma, S.; Bisi, M. M.; Kuznetsova, M. M.; Temmer, M.;
   Opgenoorth, H. J.; Belehaki, A.; Bruinsma, S.; Glover, A.; Heynderickx,
   D.; Linker, J.; Mann, I. R.; Murray, S. A.; Nandy, D.
2019AGUFMSM31C3543K    Altcode:
  The understanding and prediction of space-weather phenomena and
  their respective impact(s) on society have been widely-acknowledged
  as an international challenge and something that requires a global
  coordination and focus. In order to address this need to form
  more-formal worldwide collaboration and coordination, and to maximise
  return on such efforts (particularly scientifically), the Committee
  on Space Research (COSPAR) Panel on Space Weather (PSW) has created a
  network of International Space Weather Action Teams (ISWATs). <P />The
  COSPAR PSW ISWAT initiative is capitalising on established efforts by
  engaging existing national and international "teams" and "facilitates"
  to form individual ISWATs that are being grouped into clusters
  by domains/themes related to different aspects of solar/coronal,
  heliospheric, ionospheric/atmospheric, and planetary space-weather
  phenomena. The initiative also includes overarching themes such as
  dealing with large data sets and model/scientific validations. The
  ISWAT initiative places a strong encouragement for scientists to go
  beyond their funding borders to form ISWATs better suited to address
  challenges that one individual or small group/team may not be able to
  address alone. <P />The ISWAT initiative serves as a global hub for
  community coordinated topical focused collaborations and as a global
  community voice for the next generation of both scientific and strategic
  planning - this includes an update of the COSPAR/ILWS space weather
  scientific roadmap (to transform the roadmap into a living document)
  and to potentially provide an operational roadmap in parallel. <P
  />This presentation will re-introduce the ISWAT initiative, review
  its current status and plans for community-wide campaigns, highlight
  the overarching current plans for PSW, and place a focus on two key
  space-weather areas: the ambient heliosphere/background solar wind
  (designated as ISWAT theme H1) and CME structure, evolution and
  propagation through heliosphere (designated as ISWAT theme H2).

---------------------------------------------------------
Title: Assessing the Performance of EUHFORIA Modeling the Background
    Solar Wind
Authors: Hinterreiter, Jürgen; Magdalenic, Jasmina; Temmer, Manuela;
   Verbeke, Christine; Jebaraj, Immanuel Christopher; Samara, Evangelia;
   Asvestari, Eleanna; Poedts, Stefaan; Pomoell, Jens; Kilpua, Emilia;
   Rodriguez, Luciano; Scolini, Camilla; Isavnin, Alexey
2019SoPh..294..170H    Altcode: 2019arXiv190707461H
  In order to address the growing need for more accurate space-weather
  predictions, a new model named EUHFORIA (EUropean Heliospheric
  FORecasting Information Asset) was recently developed. We present
  the first results of the performance assessment for the solar-wind
  modeling with EUHFORIA and identify possible limitations of its present
  setup. Using the basic EUHFORIA 1.0.4 model setup with the default input
  parameters, we modeled background solar wind (no coronal mass ejections)
  and compared the obtained results with Advanced Composition Explorer
  (ACE) in-situ measurements. For the purposes of statistical study we
  developed a technique of combining daily EUHFORIA runs into continuous
  time series. The combined time series were derived for the years 2008
  (low solar activity) and 2012 (high solar activity), from which in-situ
  speed and density profiles were extracted. We find for the low-activity
  phase a better match between model results and observations compared to
  the high-activity time interval considered. The quality of the modeled
  solar-wind parameters is found to be rather variable. Therefore, to
  better understand the results obtained we also qualitatively inspected
  characteristics of coronal holes, i.e. the sources of the studied fast
  streams. We discuss how different characteristics of the coronal holes
  and input parameters to EUHFORIA influence the modeled fast solar wind,
  and suggest possibilities for the improvement of the model.

---------------------------------------------------------
Title: Refining halo CME forecast
Authors: Yordanova, E.; Werner, E.; Temmer, M.; Dimmock, A. P.;
   Rosenqvist, L.
2019AGUFMSH32A..07Y    Altcode:
  Halo CMEs are strongly geoeffective due to their direct propagation
  towards Earth. Therefore, it is of critical importance to accurately
  predict their arrival time. However, there are certain difficulties
  that make this task challenging. Usually, the quality of estimation
  of halo CME kinematics from coronagraph images suffers from projection
  effects in the plane-of-sky. In addition, the state of the background
  solar wind through which the CME is propagating should also be
  accounted for. <P />In this study, we refine the WSA-ENLIL+Cone model
  prediction by investigating one of the model input parameters, namely,
  the density enhancement factor (dcld). This parameter represents the
  density enhancement of the leading edge of the CME cone relative to the
  density enhancement of the fast solar wind. The default input is dcld
  equal to 4, which often results in higher amplitudes and earlier CME
  arrival times. We take instead the ratio between the density enhancement
  at the shock produced by the halo CME and the ambient solar wind and
  revisit the model predictions for already existing WSA-ENLIL+Cone
  runs. The new forecast results shows significant improvement in the
  arrival time estimation, suggesting that the custom dcld factor may
  be useful in space weather operational setting.

---------------------------------------------------------
Title: VizieR Online Data Catalog: Coronal hole parameters
    (Heinemann+, 2019)
Authors: Heinemann, S. G.; Temmer, M.; Heinemann, N.; Dissauer, K.;
   Samara, E.; Jercic, V.; Hofmeister, S. J.; Veronig, A. M.
2019yCatp058029401H    Altcode:
  Coronal hole parameters such as morphological properties, the intensity,
  boundary stability as well as properties of the underlying photospheric
  magnetic field and its fine structure are presented. 718 coronal holes
  between 2010 and 2019 have been extracted and analyzed from 193A
  filtergrams taken by AIA/SDO. For each coronal hole the following
  parameters are given (including uncertainties). Date, Threshold,
  Category Factor, Area, Intensity (Mean + Median), Position, Extension,
  Mean Magnetic Field Strength (Signed + Unsigned), Magnetic Flux (Signed
  + Unsigned), Flux Balance, Skewness (Magnetic Field Distribution),
  Flux Tube Number (Weak + Strong), Flux Tube Area Ratio (Weak + Strong),
  Flux Tube Flux Ratio (Weak + Strong). <P />(1 data file).

---------------------------------------------------------
Title: Reconstructing Coronal Hole Areas With EUHFORIA and Adapted
WSA Model: Optimizing the Model Parameters
Authors: Asvestari, E.; Heinemann, S. G.; Temmer, M.; Pomoell, J.;
   Kilpua, E.; Magdalenic, J.; Poedts, S.
2019JGRA..124.8280A    Altcode: 2019arXiv190703337A
  The adopted Wang-Sheeley-Arge (WSA) model embedded in EUHFORIA
  (EUropean Heliospheric FORecasting Information Asset) is compared to
  EUV observations. According to the standard paradigm, coronal holes are
  sources of open flux; thus, we use remote sensing EUV observations and
  CATCH (Collection of Analysis Tools for Coronal Holes) to extract CH
  areas and compare them to the open flux areas modeled by EUHFORIA. From
  the adopted WSA model we employ only the Potential Field Source Surface
  (PFSS) model for the inner corona and the Schatten Current Sheet
  (SCS) model for the outer (PFSS+SCS). The height, R<SUB>ss</SUB>, of
  the outer boundary of the PFSS, known as the source surface, and the
  height, R<SUB>i</SUB>, of the inner boundary of the SCS are important
  parameters affecting the modeled CH areas. We investigate the impact
  the two model parameters can have in the modeled results. We vary
  R<SUB>ss</SUB> within the interval [1.4, 3.2]R<SUB>⊙</SUB> with
  a step of 0.1R<SUB>⊙</SUB>, and R<SUB>i</SUB> within the interval
  [1.3, 2.8]R<SUB>⊙</SUB> with the same step, and the condition that
  R<SUB>i</SUB>&lt;R<SUB>ss</SUB>. This way we have a set of 184 initial
  parameters to the model, and we assess the model results for all these
  possible height pairs. We conclude that the default heights used so
  far fail in modeling accurately CH areas and lower heights need to
  be considered.

---------------------------------------------------------
Title: Statistical Analysis and Catalog of Non-polar Coronal Holes
    Covering the SDO-Era Using CATCH
Authors: Heinemann, Stephan G.; Temmer, Manuela; Heinemann, Niko;
   Dissauer, Karin; Samara, Evangelia; Jerčić, Veronika; Hofmeister,
   Stefan J.; Veronig, Astrid M.
2019SoPh..294..144H    Altcode: 2019arXiv190701990H
  Coronal holes are usually defined as dark structures seen in the extreme
  ultraviolet and X-ray spectrum which are generally associated with
  open magnetic fields. Deriving reliably the coronal hole boundary is
  of high interest, as its area, underlying magnetic field, and other
  properties give important hints as regards high speed solar wind
  acceleration processes and compression regions arriving at Earth. In
  this study we present a new threshold-based extraction method,
  which incorporates the intensity gradient along the coronal hole
  boundary, which is implemented as a user-friendly SSW-IDL GUI. The
  Collection of Analysis Tools for Coronal Holes (CATCH) enables the
  user to download data, perform guided coronal hole extraction and
  analyze the underlying photospheric magnetic field. We use CATCH
  to analyze non-polar coronal holes during the SDO-era, based on 193
  Å filtergrams taken by the Atmospheric Imaging Assembly (AIA) and
  magnetograms taken by the Heliospheric and Magnetic Imager (HMI),
  both on board the Solar Dynamics Observatory (SDO). Between 2010 and
  2019 we investigate 707 coronal holes that are located close to the
  central meridian. We find coronal holes distributed across latitudes
  of about ±60<SUP>∘</SUP>, for which we derive sizes between 1.6
  ×10<SUP>9</SUP> and 1.8 ×10<SUP>11</SUP><SUP>km2</SUP>. The absolute
  value of the mean signed magnetic field strength tends towards an
  average of 2.9 ±1.9 G. As far as the abundance and size of coronal
  holes is concerned, we find no distinct trend towards the northern
  or southern hemisphere. We find that variations in local and global
  conditions may significantly change the threshold needed for reliable
  coronal hole extraction and thus, we can highlight the importance of
  individually assessing and extracting coronal holes.

---------------------------------------------------------
Title: Photospheric magnetic structure of coronal holes
Authors: Hofmeister, Stefan J.; Utz, Dominik; Heinemann, Stephan G.;
   Veronig, Astrid; Temmer, Manuela
2019A&A...629A..22H    Altcode: 2019arXiv190903806H
  In this study, we investigate in detail the photospheric magnetic
  structure of 98 coronal holes using line-of-sight magnetograms of
  SDO/HMI, and for a subset of 42 coronal holes using HINODE/SOT G-band
  filtergrams. We divided the magnetic field maps into magnetic elements
  and quiet coronal hole regions by applying a threshold at ±25 G. We
  find that the number of magnetic bright points in magnetic elements
  is well correlated with the area of the magnetic elements (cc =
  0.83 ± 0.01). Further, the magnetic flux of the individual magnetic
  elements inside coronal holes is related to their area by a power law
  with an exponent of 1.261 ± 0.004 (cc = 0.984 ± 0.001). Relating
  the magnetic elements to the overall structure of coronal holes, we
  find that on average (69 ± 8)% of the overall unbalanced magnetic
  flux of the coronal holes arises from long-lived magnetic elements
  with lifetimes &gt; 40 h. About (22 ± 4)% of the unbalanced magnetic
  flux arises from a very weak background magnetic field in the quiet
  coronal hole regions with a mean magnetic field density of about
  0.2-1.2 G. This background magnetic field is correlated to the flux
  of the magnetic elements with lifetimes of &gt; 40 h (cc = 0.88 ±
  0.02). The remaining flux arises from magnetic elements with lifetimes
  &lt; 40 h. By relating the properties of the magnetic elements to the
  overall properties of the coronal holes, we find that the unbalanced
  magnetic flux of the coronal holes is completely determined by
  the total area that the long-lived magnetic elements cover (cc =
  0.994 ± 0.001). <P />Movie associated to Fig. 2 is available at <A
  href="https://www.aanda.org/10.1051/0004-6361/201935918/olm">https://www.aanda.org</A>

---------------------------------------------------------
Title: EVE Flare Diagnostics of in situ Observed Electron Events
Authors: Miteva, R.; Samwel, S. W.; Veronig, A.; Koleva, K.; Dechev,
   M.; Dissauer, K.; Temmer, M.; Kozarev, K.; Zabunov, S.
2019simi.conf..196M    Altcode:
  We present a comparative study between SDO/EVE flare intensity and the
  peak intensity of solar energetic electrons and protons over solar
  cycle 24 (2010–2017). For the analysis we selected flare emission
  in three EUV wavelengths: 94, 133 and 304 Å. Data from 103–175 and
  175–315 keV ACE/EPAM energy channels are used to identify and analyze
  the flux of the in situ observed electrons. SOHO/ERNE data in five
  energy channels (17–22, 26–32, 40–51, 64–80, 101–131 MeV) is
  used for the proton signatures of the so-identified electron events. We
  calculated Pearson correlation coefficients between the electron and
  proton particle fluxes and the flare EUV intensities, and compare the
  results with the respective correlations between particle flux and
  the solar flare GOES class and speed of the coronal mass ejections.

---------------------------------------------------------
Title: STEREOCat Speed de-projection of SEP-Related CMEs
Authors: Tsvetkov, Ts.; Miteva, R.; Temmer, M.; Petrov, N.
2019simi.conf..207T    Altcode:
  Particles accelerated to high energies by solar eruptive phenomena
  can reach the Earth moving along the interplanetary magnetic field
  lines. We use a list of 156 SOHO ERNE 20 MeV solar energetic particle
  (SEP) events from solar cycle 24 (2009–2017) with identified solar
  origin (e.g. flares and CMEs). The aim of this study is to evaluate
  the 3D parameters of SEP-related CMEs and estimate if they can give
  us a better insight of SEP production than the previously used 2D
  velocities. The 3D kinematic properties of the CME set are explored
  using observations from STEREO SECCHI and SOHO LASCO coronagraphs
  based on the STEREOCat analysis tool.

---------------------------------------------------------
Title: CME-HSS Interaction and Characteristics Tracked from Sun
    to Earth
Authors: Heinemann, Stephan G.; Temmer, Manuela; Farrugia, Charles J.;
   Dissauer, Karin; Kay, Christina; Wiegelmann, Thomas; Dumbović, Mateja;
   Veronig, Astrid M.; Podladchikova, Tatiana; Hofmeister, Stefan J.;
   Lugaz, Noé; Carcaboso, Fernando
2019SoPh..294..121H    Altcode: 2019arXiv190810161H
  In a thorough study, we investigate the origin of a remarkable plasma
  and magnetic field configuration observed in situ on June 22, 2011, near
  L1, which appears to be a magnetic ejecta (ME) and a shock signature
  engulfed by a solar wind high-speed stream (HSS). We identify the
  signatures as an Earth-directed coronal mass ejection (CME), associated
  with a C7.7 flare on June 21, 2011, and its interaction with a HSS,
  which emanates from a coronal hole (CH) close to the launch site of the
  CME. The results indicate that the major interaction between the CME and
  the HSS starts at a height of 1.3 R⊙ up to 3 <SUB>R⊙</SUB>. Over
  that distance range, the CME undergoes a strong north-eastward
  deflection of at least 30<SUP>∘</SUP> due to the open magnetic field
  configuration of the CH. We perform a comprehensive analysis for the
  CME-HSS event using multi-viewpoint data (from the Solar TErrestrial
  RElations Observatories, the Solar and Heliospheric Observatory and the
  Solar Dynamics Observatory), and combined modeling efforts (nonlinear
  force-free field modeling, Graduated Cylindrical Shell CME modeling,
  and the Forecasting a CME's Altered Trajectory - ForeCAT model). We aim
  at better understanding its early evolution and interaction process as
  well as its interplanetary propagation and related in situ signatures,
  and finally the resulting impact on the Earth's magnetosphere.

---------------------------------------------------------
Title: Assessment and recommendations for a consolidated European
    approach to space weather - as part of a global space weather effort
Authors: Opgenoorth, Hermann J.; Wimmer-Schweingruber, Robert F.;
   Belehaki, Anna; Berghmans, David; Hapgood, Mike; Hesse, Michael;
   Kauristie, Kirsti; Lester, Mark; Lilensten, Jean; Messerotti, Mauro;
   Temmer, Manuela
2019JSWSC...9A..37O    Altcode:
  Over the last 10-20 years there has been an ever-increasing
  international awareness of risks to modern society from adverse and
  potentially harmful - and in extreme cases even disastrous - space
  weather events. Many individual countries and even international
  organisations like the United Nations (UN) have begun to increase
  their activities in preparing for and mitigating effects of adverse
  space weather. As in the rest of the world there is also in Europe an
  urgent need for coordination of Space Weather efforts in individual
  countries as well as in and among European organisations such as
  the European Space Agency (ESA) and the European Union (EU). This
  coordination should not only improve our ability to meet space weather
  risks, but also enable Europe to contribute to on-going global space
  weather efforts. While space weather is a global threat, which needs a
  global response, it also requires tailored regional and trans-regional
  responses that require coordination at all levels. Commissioned by
  the European Space Science Committee (ESSC) of the European Science
  Foundation, the authors - together with ex-officio advice from ESA
  and the EU - have over two years assessed European activities in the
  realm of space weather and formulated a set of recommendations to ESA,
  the EU and their respective member states, about how to prepare Europe
  for the increasing impact of adverse space weather effects on man-made
  infrastructure and our society as a whole. We have also analysed
  parallel international activities worldwide, and we give advice how
  Europe could incorporate its future activities into a global scheme.

---------------------------------------------------------
Title: Spectroscopy and Differential Emission Measure Diagnostics
    of a Coronal Dimming Associated with a Fast Halo CME
Authors: Veronig, Astrid M.; Gömöry, Peter; Dissauer, Karin; Temmer,
   Manuela; Vanninathan, Kamalam
2019ApJ...879...85V    Altcode: 2019arXiv190601517V
  We study the coronal dimming caused by the fast halo CME (deprojected
  speed v = 1250 km s<SUP>-1</SUP>) associated with the C3.7 two-ribbon
  flare on 2012 September 27, using Hinode/EIS spectroscopy and Solar
  Dynamics Observatory (SDO)/AIA Differential Emission Measure (DEM)
  analysis. The event reveals bipolar core dimmings encompassed by
  hook-shaped flare ribbons located at the ends of the flare-related
  polarity inversion line, and marking the footpoints of the erupting
  filament. In coronal emission lines of log T [K] = 5.8-6.3, distinct
  double-component spectra indicative of the superposition of a stationary
  and a fast upflowing plasma component with velocities up to 130 km
  s<SUP>-1</SUP> are observed at these regions, which were mapped by the
  scanning EIS slit close in time to their impulsive dimming onset. The
  outflowing plasma component is found to be of the same order as and
  even dominant over the stationary one, with electron densities in the
  upflowing component of 2 × 10<SUP>9</SUP> cm<SUP>-3</SUP> at log T
  [K] = 6.2. The density evolution in core-dimming regions derived from
  SDO/AIA DEM analysis reveals impulsive reductions by 40%-50% within
  ≲10 minutes and remains at these reduced levels for hours. The
  mass-loss rate derived from the EIS spectroscopy in the dimming
  regions is of the same order as the mass increase rate observed in the
  associated white-light CME (1 × 10<SUP>12</SUP> g s<SUP>-1</SUP>),
  indicating that the CME mass increase in the coronagraphic field of
  view results from plasma flows from below and not from material piled
  up ahead of the outward-moving and expanding CME front.

---------------------------------------------------------
Title: Unusual Plasma and Particle Signatures at Mars and STEREO-A
    Related to CME-CME Interaction
Authors: Dumbović, Mateja; Guo, Jingnan; Temmer, Manuela; Mays,
   M. Leila; Veronig, Astrid; Heinemann, Stephan G.; Dissauer, Karin;
   Hofmeister, Stefan; Halekas, Jasper; Möstl, Christian; Amerstorfer,
   Tanja; Hinterreiter, Jürgen; Banjac, Saša; Herbst, Konstantin; Wang,
   Yuming; Holzknecht, Lukas; Leitner, Martin; Wimmer–Schweingruber,
   Robert F.
2019ApJ...880...18D    Altcode: 2019arXiv190602532D
  On 2017 July 25 a multistep Forbush decrease (FD) with a remarkable
  total amplitude of more than 15% was observed by Mars Science
  Laboratory/Radiation Assessment Detector at Mars. We find that these
  particle signatures are related to very pronounced plasma and magnetic
  field signatures detected in situ by STEREO-A on 2017 July 24, with
  a higher-than-average total magnetic field strength reaching more
  than 60 nT. In the observed time period STEREO-A was at a relatively
  small longitudinal separation (46°) to Mars, and both were located at
  the back side of the Sun as viewed from Earth. We analyze a number of
  multispacecraft and multi-instrument (both in situ and remote-sensing)
  observations and employ modeling to understand these signatures. We
  find that the solar sources are two coronal mass ejections (CMEs)
  that erupted on 2017 July 23 from the same source region on the back
  side of the Sun as viewed from Earth. Moreover, we find that the
  two CMEs interact nonuniformly, inhibiting the expansion of one of
  the CMEs in the STEREO-A direction, whereas allowing it to expand
  more freely in the Mars direction. The interaction of the two CMEs
  with the ambient solar wind adds up to the complexity of the event,
  resulting in a long, substructured interplanetary disturbance at Mars,
  where different substructures correspond to different steps of the FD,
  adding up to a globally large-amplitude FD.

---------------------------------------------------------
Title: Heliospheric Evolution of Magnetic Clouds
Authors: Vršnak, B.; Amerstorfer, T.; Dumbović, M.; Leitner, M.;
   Veronig, A. M.; Temmer, M.; Möstl, C.; Amerstorfer, U. V.; Farrugia,
   C. J.; Galvin, A. B.
2019ApJ...877...77V    Altcode: 2019arXiv190408266V
  The interplanetary evolution of 11 magnetic clouds (MCs) recorded by at
  least two radially aligned spacecraft is studied. The in situ magnetic
  field measurements are fitted to a cylindrically symmetric Gold-Hoyle
  force-free uniform-twist flux-rope configuration. The analysis
  reveals that in a statistical sense, the expansion of the studied
  MCs is compatible with self-similar behavior. However, individual
  events expose a large scatter of expansion rates, ranging from very
  weak to very strong expansion. Individually, only four events show an
  expansion rate compatible with isotropic self-similar expansion. The
  results indicate that the expansion has to be much stronger when
  the MCs are still close to the Sun than in the studied 0.47-4.8 au
  distance range. The evolution of the magnetic field strength shows a
  large deviation from the behavior expected for the case of isotropic
  self-similar expansion. In the statistical sense, as well as in most
  of the individual events, the inferred magnetic field decreases much
  slower than expected. Only three events show behavior compatible
  with self-similar expansion. There is also a discrepancy between the
  magnetic field decrease and the increase of the MC size, indicating that
  magnetic reconnection and geometrical deformations play a significant
  role in the MC evolution. About half of the events show a decay of the
  electric current as expected for self-similar expansion. Statistically,
  the inferred axial magnetic flux is broadly consistent with remaining
  constant. However, events characterized by a large magnetic flux show
  a clear tendency toward decreasing flux.

---------------------------------------------------------
Title: Three-dimensional Reconstructions of Extreme-ultraviolet Wave
    Front Heights and Their Influence on Wave Kinematics
Authors: Podladchikova, Tatiana; Veronig, Astrid M.; Dissauer, Karin;
   Temmer, Manuela; Podladchikova, Olena
2019ApJ...877...68P    Altcode: 2019arXiv190409427P
  EUV waves are large-scale disturbances in the solar corona initiated
  by coronal mass ejections. However, solar EUV images show only the
  wave front projections along the line of sight of the spacecraft. We
  perform 3D reconstructions of EUV wave front heights using multipoint
  observations from STEREO-A and STEREO-B, and we study their evolution
  to properly estimate the EUV wave kinematics. We develop two different
  methods to solve the matching problem of the EUV wave crest on
  pairs of STEREO-A/B images by combining epipolar geometry with the
  investigation of perturbation profiles. The proposed approaches are
  applicable at the early and maximum stage of the event when STEREO-A/B
  see different facets of the EUV wave, but also at the later stage when
  the wave front becomes diffusive and faint. The techniques developed
  are demonstrated on two events observed at different separations of
  the STEREO spacecraft (42° and 91°). For the 2007 December 7 event,
  we find that the emission of the EUV wave front mainly comes from a
  height range up to 90-104 Mm, decreasing later to 7-35 Mm. Including
  the varying height of the EUV wave front allows us to correct the
  wave kinematics for the projection effects, resulting in velocities
  in the range of 217-266 km s<SUP>-1</SUP>. For the 2009 February 13
  event, the wave front height almost doubled from 54 to 93 Mm over 10
  minutes, and the velocity derived is 205-208 km s<SUP>-1</SUP>. In
  the two events under study, the corrected speeds differ by up to 25%
  from the uncorrected ones, depending on the wave front height evolution.

---------------------------------------------------------
Title: Investigating the evolution and interactions of the September
    2017 CME events with EUHFORIA
Authors: Scolini, Camilla; Rodriguez, Luciano; Temmer, Manuela; Guo,
   Jingnan; Dumbovic, Mateja; Pomoell, Jens; Poedts, Stefaan
2019shin.confE...1S    Altcode:
  Coronal Mass Ejections (CMEs) are the primary source of strong
  space weather disturbances at Earth and other locations in the
  heliosphere. While their (geo-)effectiveness is largely determined
  by their dynamic pressure and magnetic field, phenomena such as
  the interaction with other transients (CMEs, CIRs…), or the
  pre-conditioning of interplanetary space due to preceding CMEs,
  can significantly alter the properties of single CME events and
  influence their (geo-)effectiveness. Investigating such phenomena
  via physics-based models is crucial to improve our understanding of
  interacting CME events, and to assess the prediction capability of
  extreme space weather events at various locations in the heliosphere. <P
  />We present a comprehensive analysis of the CME events that erupted
  from AR12673 during the unusually active week of September 4-10,
  2017, using the EUHFORIA heliospheric model. As AR12673 rotated on
  the solar disk, CMEs were launched over a wide range of longitudes,
  interacting with each other and paving the way for the propagation
  of following CMEs. CME signatures were observed at both Earth and
  Mars, and associated particle events were reported at Earth, Mars,
  and STEREO-A. At Earth, an intense geomagnetic storm triggered by
  a CME sheath interacting with a preceding ejecta was recorded on
  September 8, 2017. <P />Using parameters derived from remote-sensing
  and multi-spacecraft observations of the CMEs and their source
  region, we simulate the events with both traditional cone CME model,
  and with a more realistic flux-rope CME model. We investigate how
  CME-CME interactions affect the spatial and temporal evolution of CME
  shocks, sheaths and ejecta in the heliosphere, and we compare simulation
  results with in-situ measurements at Earth and Mars. This study will not
  only benchmark current prediction capabilities in the case of complex
  CME events, but will also provide better insights on the large-scale
  evolution of complex CME events throughout the heliosphere.

---------------------------------------------------------
Title: ELEvoHI ensemble modeling: CME arrival prediction based on
    heliospheric imager observations
Authors: Hinterreiter, Jürgen; Amerstorfer, Tanja; Temmer, Manuela;
   Möstl, Christian; Reiss, Martin; Amerstorfer, Ute; Bailey, Rachel
2019EGUGA..21.9132H    Altcode:
  We present a statistical study on CME arrival prediction using ELEvoHI
  (ELlipse Evolution model based on Heliospheric Imager observations)
  ensemble modeling. ELEvoHI is the current state-of-the-art HI
  elongation fitting method that utilizes heliospheric imager data
  obtained by the STEREO (Solar TErrestrial RElations Observatory)
  twin spacecraft assuming that the drag force exerted by the ambient
  solar wind is the dominant force influencing the CME propagation in
  the IP-space. The HI time-elongation profiles needed by ELEvoHI as
  well as the in-situ data for validating the results are taken from
  the FP7 HELCATS project. GCS (Graduated Cylindrical Shell) fitting
  is applied for each CME separately. We perform a cut in the ecliptic
  plane, based on the GCS fit, to derive the initial values needed
  for the ELEvoHI ensemble modeling. In this study, we select CMEs
  in a 12-month interval (June 2009 to June 2010) corresponding to a
  location of STEREO-B close to Lagrange point 5 (60° trailing Earth),
  making the model results valuable for future studies (STEREO-A near
  L5 in mid 2020) and for a planned L5 mission. Our analysis contains
  two parts: First, a contingency table (hit/false alarms/misses) with
  the corresponding skill scores and second the times and speeds for the
  predicted and observed Earth arriving events. The statistical results
  are compared to other studies and will serve as benchmark for future
  enhanced ELEvoHI versions.

---------------------------------------------------------
Title: Genesis, magnetic morphology and impulsive evolution of
    the coronal mass ejection associated with the X8.2 flare on 2017
    September 10
Authors: Veronig, Astrid; Podladchikova, Tatiana; Dissauer, Karin;
   Temmer, Manuela; Seaton, Daniel; Long, David; Guo, Jingnan; Vrsnak,
   Bojan; Harra, Louise; Kliem, Bernhard
2019EGUGA..21.9243V    Altcode:
  The extreme X8.2 event of 2017 September 10 provides unique observations
  to study the genesis, magnetic morphology, impulsive dynamics and
  shock formation in a very fast coronal mass ejection (CME). Combining
  GOES-16/SUVI and SDO/AIA EUV imagery, we identify a hot (T ≈ 10-15
  MK) bright rim around a quickly expanding cavity, embedded inside a
  much larger CME shell (T ≈ 1-2 MK). The CME shell develops from a
  dense set of large AR loops (&gt;0.5Rs) and seamlessly evolves into
  the CME front observed in LASCO C2. The strong lateral overexpansion
  of the CME shell acts as a piston initiating the fast EUV shock
  wave. The hot cavity rim is demonstrated to be a manifestation of
  the dominantly poloidal flux and frozen-in plasma added to the rising
  flux rope by magnetic reconnection in the current sheet beneath. The
  same structure is later observed as the core of the white-light CME,
  challenging the traditional interpretation of the CME three-part
  morphology. The large amount of added magnetic flux suggested by these
  observations explains the extreme accelerations of the radial and
  lateral expansion of the CME shell and cavity, all reaching values
  up to 5-10 km s-2. The acceleration peaks occur simultaneously with
  the first RHESSI 100-300 keV hard X-ray burst of the associated flare,
  further underlining the importance of the reconnection process for the
  impulsive CME evolution. Finally, the much higher radial propagation
  speed of the flux rope in relation to the CME shell causes a distinct
  deformation of the white-light CME front and shock.

---------------------------------------------------------
Title: Statistics of Coronal Dimmings Associated with Coronal Mass
    Ejections. II. Relationship between Coronal Dimmings and Their
    Associated CMEs
Authors: Dissauer, K.; Veronig, A. M.; Temmer, M.; Podladchikova, T.
2019ApJ...874..123D    Altcode: 2018arXiv181001589D
  We present a statistical study of 62 coronal dimming events associated
  with Earth-directed coronal mass ejections (CMEs) during the
  quasi-quadrature period of STEREO and the Solar Dynamics Observatory
  (SDO). This unique setting allows us to study both phenomena in great
  detail and compare characteristic quantities statistically. Coronal
  dimmings are observed on-disk by the SDO/Atmospheric Imaging Assembly
  and the Helioseismic and Magnetic Imager, while the CME kinematics
  during the impulsive acceleration phase is studied close to the limb
  with STEREO/EUVI and COR, minimizing projection effects. The dimming
  area, its total unsigned magnetic flux, and its total brightness,
  reflecting properties of the total dimming region at its final extent,
  show the highest correlations with the CME mass (c ∼ 0.6-0.7). Their
  corresponding time derivatives, describing the dynamics of the dimming
  evolution, show the strongest correlations with the CME peak velocity
  (c ∼ 0.6). The highest correlation of c = 0.68 ± 0.08 is found
  with the mean intensity of dimmings, indicating that the lower the
  CME starts in the corona, the faster it propagates. No significant
  correlation between dimming parameters and the CME acceleration was
  found. However, for events where high-cadence STEREO observations were
  available, the mean unsigned magnetic field density in the dimming
  regions tends to be positively correlated with the CME peak acceleration
  (c = 0.42 ± 0.20). This suggests that stronger magnetic fields result
  in higher Lorentz forces providing stronger driving force for the CME
  acceleration. Specific coronal dimming parameters correlate with both
  CME and flare quantities providing further evidence for the flare-CME
  feedback relationship. For events in which the CME occurs together
  with a flare, coronal dimmings statistically reflect the properties
  of both phenomena.

---------------------------------------------------------
Title: Importance of heliospheric imager track quality for CME
    arrival prediction accuracy
Authors: Amerstorfer, Tanja; Hinterreiter, Jürgen; Möstl, Christian;
   Davies, Jackie A.; Amerstorfer, Ute V.; Reiss, Martin A.; Temmer,
   Manuela; Bailey, Rachel L.; Harrison, Richard A.
2019EGUGA..21.7373A    Altcode:
  Operational CME arrival prediction is mainly conducted using
  magnetohydrodynamic models based on coronagraph observations and
  magnetograms. Although the Solar TErrestrial RElations Observatory with
  its heliospheric imagers (HI) provides the possibility to trace a CME's
  propagation along its path from the Sun to 1 AU, these data can hardly
  be used to predict CME arrivals in real time (except for a few events
  in an early phase of the mission). One of the main reasons for that
  is a large number of data gaps in beacon data, which is available in
  near real time (in contrast to the complete science data), impeding a
  proper measurement of the CME front. With regard to a possible future L5
  mission carrying HIs we investigate the most suitable way of extracting
  the time-elongation track of CMEs from HI observations leading to
  a prediction with the highest possible accuracy. As a first step to
  reach this goal, we use time-elongation tracks measured from STEREO/HI
  science data and provided by the FP7 HELCATS team as well as tracks
  derived using time-elongation maps and tracks measured directly in an
  HI image time series. These time-elongation tracks are further used as
  input to our CME ensemble prediction tool ELEvoHI (ELlipse Evolution
  model based on HI data), which assumes a drag-based interplanetary
  CME propagation and an elliptical CME frontal shape. ELEvoHI produces
  post-event predictions of arrival times and speeds at 1 AU for all
  tracks of each CME under study. By comparing the prediction results from
  several ways of tracking we attempt to deduce a preferable approach
  for future studies, e.g. when using data from Parker Solar Probe's
  Wide-Field Imager for Solar Probe (WISPR), and maybe for future real
  time predictions when STEREO-A approaches the L5 point.

---------------------------------------------------------
Title: Observational assessment on CME mass pile up in interplanetary
    space
Authors: Temmer, Manuela; Holzknecht, Lukas; Dumbovic, Mateja;
   Vrsnak, Bojan
2019EGUGA..21.9578T    Altcode:
  Coronal mass ejections (CMEs) propagating in the heliosphere are
  exposed to a drag force due to the ambient solar wind. Mass pile-up
  in interplanetary space can have strong effects on the drag force,
  and with that on the CME propagation time and energy input to the
  magnetosphere. For a sample of well observed events, we determine
  the de-projected 3D mass and its evolution up to a distance range
  of about 15Rs using combined STEREO-SECCHI COR1 and COR2 data, for
  which no pile-up at the CME front is found (see also Bein et al.,
  2013). Applying the GCS forward fitting model (Thernisien et al., 2006,
  2009) on COR2 data, we obtain the volume of the CMEs. Working under the
  assumption that the CME mass is constant beyond 15Rs and that the CME
  undergoes self-similar expansion, we estimate the CME density at the
  distance of 1AU. The results are compared to in-situ proton density
  data measured for the associated ICME's sheath and magnetic structure
  for which we derive a trend towards a mass increase at the CME front.

---------------------------------------------------------
Title: Investigating the evolution and interactions of the September
    2017 CME events with EUHFORIA
Authors: Scolini, Camilla; Rodriguez, Luciano; Temmer, Manuela; Guo,
   Jingnan; Dumbovic, Mateja; Pomoell, Jens; Poedts, Stefaan
2019EGUGA..21.1337S    Altcode:
  Coronal Mass Ejections (CMEs) and their Interplanetary counterparts
  (ICMEs) are the primary source of strong space weather disturbances at
  Earth and other places in the heliosphere. Key parameters determining
  the geo-effectiveness of CMEs are their plasma dynamic pressure
  and internal magnetic field intensity and orientation. In addition,
  phenomena such as the interaction with other CME structures along the
  way, or the pre-conditioning of interplanetary (IP) space due to the
  passage of previous CMEs, can significantly modify the properties of
  single CME events and influence their geo-effectiveness. Therefore,
  investigating and modeling such phenomena via physics-based heliospheric
  models is crucial in order to assess and improve our space weather
  prediction capability in relation to complex CME events. In this regard,
  we present a comprehensive analysis of the CME events that erupted from
  AR 12673 during the unusually active week of September 4-10, 2017, with
  the aim of validating for the first time the prediction capabilities
  of the EUHFORIA model in the case of complex CME events. As AR 12673
  rotated along with the solar disk, CMEs were launched over a wide
  range of longitudes, interacting with each other and paving the way
  for the propagation of the following CMEs. Following the eruptions,
  ICME-related signatures were observed at both Earth and Mars,
  while associated particle events were reported at Earth, Mars, and
  STEREO-A. In terms of impact on Earth, an intense geomagnetic storm,
  triggered by a strong southward magnetic field associated to an ICME
  sheath, was recorded on September 8, 2017. In order to study these
  CME-CME interactions and their influence on the geo-effectiveness of
  single CMEs, we simulate the events using the EUHFORIA model. With
  the intent of preserving a predictive approach, we use kinematic,
  geometric and magnetic input parameters for the CMEs as derived from
  remote-sensing and multi-spacecraft observations of the CMEs and
  their source regions. We model CMEs first using an over-simplified
  cone model, and then a more realistic flux- rope model so to quantify
  the improvement in the prediction of the interplanetary magnetic field
  and CME geo-effectiveness at Earth in the latter case. Furthermore,
  we investigate the modelling of CME-CME interactions considering the
  spatial and temporal evolution of ICMEs in terms of their shocks,
  sheaths and ejecta structures in the heliosphere, and we quantify the
  impact of such phenomena on the propagation and evolution of single
  CME events. Results from this study will not only benchmark our
  current prediction capabilities in the case of complex CME events,
  but will also provide better insights on the large-scale evolution
  and interaction of complex CME events in the inner heliosphere.

---------------------------------------------------------
Title: Stellar CMEs from an observational point of view
Authors: Leitzinger, Martin; Odert, Petra; Vida, Krisztian; Koller,
   Florian; Veronig, Astrid; Korhonen, Heidi; Guenther, Eike; Hanslmeier,
   Arnold; Temmer, Manuela; Dissauer, Karin; Greimel, Robert; Kriskovics,
   Levente; Lammer, Helmut
2019EGUGA..21.6786L    Altcode:
  Stellar activity is mainly characterized by the high energy phenomena
  such as outbreaks of radiation (flares) and sporadic expulsions
  of particles into the astrosphere termed coronal mass ejections
  (CMEs). Both phenomena are known to cause space weather in our solar
  system. On stars, flares and their parameters are well determined,
  in contrast to CMEs; their parameters are still not determined
  statistically. Both phenomena may have severe effects on planetary
  atmospheres and, in addition, stellar CMEs may play an important
  role in stellar mass and angular momentum loss and therefore in
  stellar evolution. Flares are directly detectable from photometric
  observations, whereas the detection of CMEs requires different
  observational methods. CMEs have different signatures in different
  wavelength regimes. Most of the stellar CMEs were detected so far
  using the method of Doppler-shifted Balmer flux which is accessible via
  spectroscopic measurements. Several observational programs have been
  carried out and are planned for the future, including new observations
  and archival data. Also several attempts to detect stellar CMEs via
  radio emission have been carried out in the past decades. Finally,
  the X-ray regime may provide a valuable data pool to look for so-called
  dimmings, well-known from the Sun, which are closely related to CMEs and
  which are detectable in X-ray light curves. So far stellar CMEs have
  been detected rarely and only a handful of distinct events is known,
  mainly for dMe stars. We report on past, ongoing and future campaigns
  of stellar CMEs on F-, G-, K-, and M-type pre- and main-sequence stars.

---------------------------------------------------------
Title: Multiple Satellite Analysis of the Earth's Thermosphere and
    Interplanetary Magnetic Field Variations due to ICME/CIR Events
    During 2003-2015
Authors: Krauss, Sandro; Temmer, Manuela; Vennerstrom, Susanne
2019EGUGA..21.4180K    Altcode:
  We present a refined statistical analysis based on ICMEs as well as
  CIRs for the time period 2003-2015 to estimate the impact of different
  solar wind types on the geomagnetic activity and the neutral density
  in the Earth's thermosphere. For the time-based delimitation of the
  events, we rely on the catalog maintained by Richardson and Cane and
  the corotating interaction region lists provided by S. Vennerstrom
  and L.K. Jian. These archives are based on in situ measurements from
  the ACE and/or the Wind spacecraft. On this basis, we will thoroughly
  investigate about 400 Earth-directed ICME and CIR events. To verify the
  impact on the Earths thermosphere we determine neutral mass densities
  by using accelerometer measurements collected by the low-Earth-orbiting
  satellites GRACE and CHAMP. Subsequently, the atmospheric densities
  will be to characteristic ICME parameters and since increased solar
  activity may lead to a decrease of the satellites orbital altitude
  we additionally assess the orbital decay for each of the events and
  satellites.

---------------------------------------------------------
Title: The in situ Solar Wind and Galactic Cosmic Ray correlation
    at Mars and its comparison with Earth observations
Authors: Guo, Jingnan; Temmer, Manuela; Veronig, Astrid; Janvier,
   Miho; Hofmeister, Stefan; Wimmer-Schweingruber, Robert; Halekas, Jasper
2019EGUGA..21.9366G    Altcode:
  The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft have
  been observing the in situ solar wind properties since its arrival to
  Mars at the end of 2014. Together with the Galactic Cosmic Ray (GCR)
  observation continuously monitored by the Radiation Assessment Detector
  (RAD) on the Martian ground, we are able to analyze the correlation of
  the solar wind evolution and the modulated GCR variations at Mars. The
  transient variations (mostly observed as short-term decreases) in
  these in situ observations are usually related to either the impact
  of Coronal Mass Ejections (CMEs) erupted from Solar active regions or
  the pass-by of High Speed Streams (HSS) in the solar wind arising from
  Coronal Holes (CHs) on the Sun. During the opposition phase in 2016
  when Earth and Mars were radially aligned on the same side of the Sun,
  we observe the stable evolution of a few CHs on the solar surface over
  several solar rotations and analyze the re-current in situ solar wind
  and GCR signatures at both Earth and Mars.

---------------------------------------------------------
Title: Unusual plasma and particle signatures at Mars and STEREO-A
    related to inhibited expansion caused by CME-CME interaction
Authors: Dumbovic, Mateja; Guo, Jingnan; Temmer, Manuela; Mays, Leila;
   Veronig, Astrid; Hofmeister, Stefan; Halekas, Jasper
2019EGUGA..21.6957D    Altcode:
  On July 25 2017 a multi-step Forbush decrease (FD) with the total
  amplitude of more than 15% was observed by MSL/RAD at Mars and this
  is one of the biggest FDs ever detected on Mars. We find that these
  particle signatures are related to very pronounced plasma and magnetic
  field signatures detected in situ by STEREO-A on July 24 2017, with a
  higher than average total magnetic field strength reaching more than
  60 nT. In the observed time period STEREO-A was longitudinally close
  to Mars and both were located at the back side of Sun as viewed from
  Earth. Using multi-spacecraft and multi-instrument (both in situ and
  remote-sensing) observations, as well as modelling, we find that the
  solar sources of these in situ signatures are 2 CMEs which erupted on
  July 23 2017 from the same source region on the back side of the Sun as
  viewed from Earth and interacted in the interplanetary space, inhibiting
  the expansion of one of the CMEs. We present a detailed investigation
  on this complex interaction event on its way from Sun to Mars. This
  project has received funding from the European Union's Horizon 2020
  research and innovation programme under the Marie Skłodowska-Curie
  grant agreement No 745782.

---------------------------------------------------------
Title: Multiple EUV wave reflection from a coronal hole
Authors: Podladchikova, Tatiana; Veronig, Astrid M.; Podladchikova,
   Olena; Dissauer, Karin; Vršnak, Bojan; Saqri, Jonas; Piantschitsch,
   Isabell; Temmer, Manuela
2019EGUGA..21.9793P    Altcode:
  EUV waves are large-scale propagating disturbances in the solar corona
  initiated by coronal mass ejections. We investigate the multiple EUV
  wave reflections at a coronal hole boundary, as observed by SDO/AIA on 1
  April 2017. The EUV wave originates from Active Region (AR) 12645 close
  to the disk center and propagates toward the south polar coronal hole
  with an average velocity of 430 km/s. The interaction of the EUV wave
  with the coronal hole, which represents a region of high Alfven speed,
  is observed as a splitting into two wave components: one continues
  propagation inside the coronal hole with an increased velocity of 850
  km/s (transmitted wave), while the other one moves back toward the AR,
  also with an increased velocity of 600 km/s (reflected wave). The
  reflected EUV wave is subsequently reflected again from the AR and
  propagates toward the coronal hole with an average velocity of 350
  km/s, where it is reflected for the second time at the coronal hole
  boundary and propagates again toward the AR with a velocity of 300
  km/s. These events are observed over an interval of 40 minutes. The
  high cadence SDO imagery allows us to study in detail the kinematics
  of the direct and multiple times reflected EUV wave. In addition, its
  multi-wavelength EUV imagery allows us to derive the plasma properties
  of the corona and the EUV wave pulse via Differential Emission Measure
  analysis. These results are used to compare the observed characteristics
  of the wave interaction with the coronal hole with simulations.

---------------------------------------------------------
Title: Origin of the two shock waves associated with the September
    27/28, 2012 event
Authors: Jebaraj, Immanuel Christopher; Magdalenic, Jasmina; Scolini,
   Camilla; Rodriguez, Luciano; Poedts, Stefaan; Kilpua, Emilia; Krupar,
   Vratislav; Pomoell, Jens; Temmer, Manuela
2019EGUGA..2116967J    Altcode:
  Coronal mass ejections and flares are solar eruptive phenomena
  responsible for space weather activities near Earth. They can
  accelerate particles, and generate shock waves which are a threat to
  our technologies at Earth and in space. Therefore, predicting shock
  arrival at Earth has been an important goal for space weather. Space
  based radio observations provide the unique opportunity to track shock
  waves in the inner heliosphere. We present the study of CME/flare event
  on September 27/28, 2012. The GOES C3.1 flare that originated from NOAA
  AR 1577 was associated with a full-halo CME (first seen in SOHO/LASCO
  C2 field of view at 23:47) and white light shock wave observed by all
  three spacecraft STEREO A, STEREO B, and SOHO. The associated radio
  event shows a group of type III bursts and two somewhat unusual type II
  bursts with significantly different starting frequencies. To understand
  the origin of the two shock waves we performed multi-wavelength study,
  and perform radio triangulation to get their source position in the
  3D space. For the radio triangulation study, we used goniopolarimetric
  measurements from STEREO/WAVES and WIND/WAVES instruments. We also did
  data-driven modelling of the CME propagation using EUHFORIA cone model
  (EUropean Heliospheric FORecasting Information Asset) and validate
  the results by comparison with in-situ data. Results of this study
  indicate that, although temporal association between the shock and
  the CME is good, the low frequency type II burst occurs significantly
  higher in the solar corona than the associated CME and has therefore
  unclear origin. To understand the origin of the low frequency type
  II burst we studied preceding event at 10:20 UT (STEREO A/COR2) on
  September 27, 2012. The radio triangulation study shows that the type
  II source positions are in the southern solar hemisphere and thus may
  be associated to the type II emissions in the radio event succeeding
  it. We therefore discuss different possibilities for the origin of
  two type II bursts.

---------------------------------------------------------
Title: Radial and Tangential Kinematics and Angular Extent of EUV
    Coronal Bright Fronts
Authors: Kozarev, Kamen; Veronig, Astrid; Temmer, Manuela; Miteva,
   Rositsa; Dissauer, Karin; Koleva, Kostadinka; Dechev, Momchil;
   Duchlev, Peter
2019EGUGA..21.9290K    Altcode:
  Large-scale solar coronal compressive waves are often observed
  in extreme UV (EUV) and white light to precede nascent coronal
  mass ejections (CMEs), which previous work has shown develop most
  dynamically (expansion, acceleration) in the low and middle solar corona
  (below 5-8 solar radii). Multiple studies in the last ten years have
  suggested that these waves may be manifestations of driven coronal
  shock waves, and may accelerate ions to solar energetic particle
  (SEP) energies. A commonly invoked condition for the generation of
  EUV waves and their capability to produce energetic particles is the
  presence of rapid lateral expansion of the front and driver behind
  it. As a step to characterizing this capability, we study the radial
  and lateral kinematics of a number of EUV off-limb waves in the low
  corona, and their departure from spherical expansion. We characterize
  their time-dependent angular extent. We compare the results with
  the later-stage CME angular sizes and radial kinematics deduced from
  SOHO/LASCO observations of the events.

---------------------------------------------------------
Title: Analysis of SDO/EVE Flares in Relation to Solar Energetic
    Protons
Authors: Miteva, Rositsa; Koleva, Kostadinka; Dechev, Momchil; Veronig,
   Astrid; Dissauer, Karin; Kozarev, Kamen; Temmer, Manuela
2019EGUGA..2115190M    Altcode:
  Solar energetic proton (SEP) events from SOHO/ERNE instruments
  and SDO/EVE solar flares in solar cycle 24 are considered. The
  SEP-associated flare emission is analyzed in multiple wavelength
  ranges characterizing flare emission. Background subtraction of
  the pre-event particle flux and flare emission is performed for
  each event. Finally, a Pearson correlation analysis is completed
  between the peak values of the SEP events and the UV and EUV flare
  intensities. Comparison with the results from flare soft X-ray, hard
  X-ray and radio emission is presented. This work is supported by the
  Bilateral project Bulgaria-Austria with the National Science Fund of
  Bulgaria contract No. NTS/AUSTRIA 01/23 (28.02.2017) and Austria OeAD
  Project No. BG 11/2017.

---------------------------------------------------------
Title: Reconstructing coronal holes with EUHFORIA
Authors: Asvestari, Eleanna; Heinemann, Stephan; Pomoell, Jens;
   Temmer, Manuela; Kilpua, Emilia; Magdalenic, Jasmina; Poedts, Stefaan
2019EGUGA..21.8085A    Altcode:
  Modelling accurately the ambient solar wind is important for space
  weather forecasting. EUHFORIA (European Heliospheric Forecasting
  Information Asset) model employs an empirical solar wind model that is
  based on the Wang-Sheeley-Arge model. It combines the Potential Field
  Source Surface (PFSS) and the Schatten Current Sheet (SCS) models. In
  previous studies it was shown that placing the inner boundary of the
  SCS model at a radius, Ri, lower than that of the outer boundary of the
  PFSS model, Rii, improves the simulation output. Here, we investigate
  the capability of the empirical solar wind model adopted in EUHFORIA
  to recreate the geometry and size of coronal holes for a large set of
  pairs of PFSS and SCS radii. We vary Rii within the interval [1.4,
  3.0]Rs with a step of 0.1Rs, and the Ri within the interval [1.3,
  2.8]Rs with the same step size. The study is repeated for 12 coronal
  holes of different latitudinal position and geometry. We compare the
  modelled coronal holes with boundaries obtained by remote sensing
  EUV observations using the CATCH tool (Collection of Analysis Tools
  for Coronal Holes). Preliminary results of the study indicate that a
  previously defined pair of PFSS and SCS radii results in underestimated
  coronal hole sizes. It also indicates that different radii sets give
  better results for different types of coronal holes.

---------------------------------------------------------
Title: ICMEs Propagating Towards Mars Observed in Heliospheric
    Imagers and their Associated Forbush Decreases at MSL/RAD
Authors: von Forstner, Johan; Guo, Jingnan; Wimmer-Schweingruber,
   Robert F.; Temmer, Manuela; Dumbović, Mateja; Veronig, Astrid; Möstl,
   Christian; Hassler, Donald M.; Zeitlin, Cary J.; Ehresmann, Bent
2019EGUGA..21.8305V    Altcode:
  The Radiation Assessment Detector (RAD) onboard the Mars Science
  Laboratory (MSL) mission's Curiosity rover has been measuring galactic
  cosmic rays (GCR) as well as solar energetic particles (SEP) on the
  surface of Mars for more than 6 years since its landing in August
  2012 and in interplanetary space during its 8-month cruise to Mars
  between 2011 and 2012. The observations include a large number of
  Forbush decreases (FD) caused by interplanetary coronal mass ejections
  (ICMEs) and their associated shocks passing MSL. Our previous work
  (Freiherr von Forstner et al. 2018, JGR: Space Physics) studied 15
  ICME events close to oppositions of Mars as seen from Earth or the
  STEREO A and B spacecraft, where in situ Forbush decrease observations
  at both locations could be used to derive the propagation time of the
  ICME from 1 AU to Mars. We found that on average, ICMEs in our sample
  continued to decelerate beyond 1 AU. We now investigate a different
  constellation where MSL/RAD Forbush decrease measurements are combined
  with remote tracking of ICMEs using the STEREO Heliospheric Imager (HI)
  telescopes. A large catalog of such remote observations was created
  by the HELCATS project (Möstl et al. 2017, Space Weather), not only
  including ICMEs propagating towards Earth, but also some that passed
  Mars. This allows to enlarge our sample for a statistical study of
  ICMEs at Mars. We associate STEREO-HI observations from the catalog with
  corresponding FDs at MSL/RAD and study the accuracy when predicting the
  arrival of an ICME at Mars using common models applied to HI data. Based
  on the catalogue of events built using this method, we also investigate
  the properties of the corresponding Forbush decreases at RAD, such
  as their magnitude, steepness and duration. We find both correlations
  between the parameters themselves as well as possible relations to the
  ICME properties (derived from HI data). These data are also compared
  to findings from previous studies using Earth-based observations.

---------------------------------------------------------
Title: Benchmarking CME Arrival Time and Impact: Progress on Metadata,
    Metrics, and Events
Authors: Verbeke, C.; Mays, M. L.; Temmer, M.; Bingham, S.; Steenburgh,
   R.; Dumbović, M.; Núñez, M.; Jian, L. K.; Hess, P.; Wiegand, C.;
   Taktakishvili, A.; Andries, J.
2019SpWea..17....6V    Altcode: 2018arXiv181110695V
  Accurate forecasting of the arrival time and subsequent geomagnetic
  impacts of coronal mass ejections (CMEs) at Earth is an important
  objective for space weather forecasting agencies. Recently, the CME
  Arrival and Impact working team has made significant progress toward
  defining community-agreed metrics and validation methods to assess
  the current state of CME modeling capabilities. This will allow the
  community to quantify our current capabilities and track progress in
  models over time. First, it is crucial that the community focuses
  on the collection of the necessary metadata for transparency and
  reproducibility of results. Concerning CME arrival and impact we have
  identified six different metadata types: 3-D CME measurement, model
  description, model input, CME (non)arrival observation, model output
  data, and metrics and validation methods. Second, the working team
  has also identified a validation time period, where all events within
  the following two periods will be considered: 1 January 2011 to 31
  December 2012 and January 2015 to 31 December 2015. Those two periods
  amount to a total of about 100 hit events at Earth and a large amount
  of misses. Considering a time period will remove any bias in selecting
  events and the event set will represent a sample set that will not be
  biased by user selection. Lastly, we have defined the basic metrics and
  skill scores that the CME Arrival and Impact working team will focus on.

---------------------------------------------------------
Title: Genesis and Impulsive Evolution of the 2017 September 10
    Coronal Mass Ejection
Authors: Veronig, Astrid M.; Podladchikova, Tatiana; Dissauer, Karin;
   Temmer, Manuela; Seaton, Daniel B.; Long, David; Guo, Jingnan; Vršnak,
   Bojan; Harra, Louise; Kliem, Bernhard
2018ApJ...868..107V    Altcode: 2018arXiv181009320V
  The X8.2 event of 2017 September 10 provides unique observations
  to study the genesis, magnetic morphology, and impulsive dynamics
  of a very fast coronal mass ejection (CME). Combining GOES-16/SUVI
  and SDO/AIA EUV imagery, we identify a hot (T ≈ 10-15 MK) bright
  rim around a quickly expanding cavity, embedded inside a much larger
  CME shell (T ≈ 1-2 MK). The CME shell develops from a dense set of
  large AR loops (≳0.5R <SUB> s </SUB>) and seamlessly evolves into
  the CME front observed in LASCO C2. The strong lateral overexpansion
  of the CME shell acts as a piston initiating the fast EUV wave. The
  hot cavity rim is demonstrated to be a manifestation of the dominantly
  poloidal flux and frozen-in plasma added to the rising flux rope by
  magnetic reconnection in the current sheet beneath. The same structure
  is later observed as the core of the white-light CME, challenging the
  traditional interpretation of the CME three-part morphology. The large
  amount of added magnetic flux suggested by these observations explains
  the extreme accelerations of the radial and lateral expansion of the CME
  shell and cavity, all reaching values of 5-10 km s<SUP>-2</SUP>. The
  acceleration peaks occur simultaneously with the first RHESSI 100-300
  keV hard X-ray burst of the associated flare, further underlining
  the importance of the reconnection process for the impulsive CME
  evolution. Finally, the much higher radial propagation speed of the
  flux rope in relation to the CME shell causes a distinct deformation
  of the white-light CME front and shock.

---------------------------------------------------------
Title: CME-driven Shock and Type II Solar Radio Burst Band Splitting
Authors: Chrysaphi, Nicolina; Kontar, Eduard P.; Holman, Gordon D.;
   Temmer, Manuela
2018ApJ...868...79C    Altcode: 2018arXiv181008026C
  Coronal mass ejections (CMEs) are believed to be effective in
  producing shocks in the solar corona and interplanetary space. One of
  the important signatures of shocks and shock acceleration are Type II
  solar radio bursts that drift with the shock speed and produce bands of
  fundamental and higher harmonic plasma radio emission. An intriguing
  aspect of Type II radio bursts is the occasional split of a harmonic
  band into thinner lanes, known as band splitting. Here we report a
  detailed imaging and spectroscopic observation of a CME-driven shock
  producing band splitting in a Type II burst. Using LOFAR, we examine the
  spatial and temporal relation of the Type II burst to the associated
  CME event, use source imaging to calculate the apparent coronal
  density, and demonstrate how source imaging can be used to estimate
  projection effects. We consider two widely accepted band-splitting
  models that make opposing predictions regarding the locations of the
  true emission sources with respect to the shock front. Our observations
  suggest that the locations of the upper and lower subband sources
  are spatially separated by ∼0.2 ± 0.05 R <SUB>⊙</SUB>. However,
  we quantitatively show, for the first time, that such separation is
  consistent with radio-wave scattering of plasma radio emission from
  a single region, implying that the split-band Type II sources could
  originate from nearly cospatial locations. Considering the effects
  of scattering, the observations provide supporting evidence for the
  model that interprets the band splitting as emission originating in
  the upstream and downstream regions of the shock front, two virtually
  cospatial areas.

---------------------------------------------------------
Title: Coronal holes detection using supervised classification
Authors: Delouille, Veronique; Hofmeister, Stefan; Reiss, Martin;
   Mampaey, Benjamin; Temmer, Manuela; Veronig, Astrid
2018csc..confE..93D    Altcode:
  We demonstrate the use of machine learning algorithms in combination
  with segmentation techniques in order to distinguish coronal holes
  and filaments in solar EUV images. We used the Spatial Possibilistic
  Clustering Algorithm (SPoCA) to prepare data sets of manually labeled
  coronal hole and filament channel regions present on the Sun during
  the time range 2010-2016. By mapping the extracted regions from EUV
  observations onto HMI line-of-sight magnetograms we also include
  their magnetic characteristics. We computed average latitude, area,
  shape measures from the segmented binary maps as well as first order,
  and second order texture statistics from the segmented regions in the
  EUV images and magnetograms. These attributes were used for data mining
  investigations to identify the most performant rule to differentiate
  between coronal holes and filament channels, taking into account the
  imbalance in our dataset which contains one filament channel for 15
  coronal holes. We tested classifiers such as Support Vector Machine,
  Linear Support Vector Machine, Decision Tree, k-Nearest Neighbors, as
  well as ensemble classifier based on Decision Trees. Best performance
  in terms of True Skill Statistics are obtained with cost-sensitive
  learning, Support Vector Machine classifiers, and when HMI attributes
  are included in the dataset.

---------------------------------------------------------
Title: The photospheric structure of coronal holes: magnetic elements
Authors: Hofmeister, Stefan; Utz, Dominik; Heinemann, Stephan; Veronig,
   Astrid; Temmer, Manuela
2018csc..confE.129H    Altcode:
  Coronal holes attracted recently more attention by the scientific
  community as they represent the source region for the fast solar wind
  which is ifself an important ingredient in understanding the space
  environment and space weather. Nevertheless, our knowledge about
  the detailed magnetic field structure below coronal holes is quite
  limited, maybe since such a research would necessarily involve the high
  atmospheric and photospheric community. In this contribution we would
  like to bridge this gap and investigate in detail the magnetic field
  distribution below coronal holes and its relationship to the large-scale
  coronal hole topology. To do so, we investigate the distribution and
  properties of photospheric magnetic elements below 106 low and medium
  latitude coronal holes using SDO/HMI line-of-sight magnetogram data from
  2010 to 2016, and relate them to the overall properties of the coronal
  holes. Since magnetic elements produce clearly visible photospheric
  structures, they can be well observed and give us valuable insights into
  the structure of coronal holes. We find that the distribution of the
  magnetic flux of magnetic elements follows an exponential function. The
  area and flux of magnetic elements are strongly related to each other
  by a power law with an exponent of 1.25. The larger magnetic elements
  are located at the edges of the magnetic network and seem to be the
  "core" structure of coronal holes. They have lifetimes &gt; 4 days,
  i.e., longer than the timescale of the supergranulation. Further, they
  contain up to 50 magnetic bright points as observed by Hinode/SOT in
  the G-Band, meaning that the large magnetic elements are large clusters
  of individual magnetic elements. The mean magnetic field density of
  the overall coronal holes and thus their unbalanced magnetic flux
  is determined by their percentage coverage with magnetic elements
  at cc=0.98. Since magnetic elements are the foot points of magnetic
  funnels and thus the small-scale source regions of high-speed solar
  wind streams, the dependence of the coverage with magnetic elements
  on the strength of coronal holes also explains the dependence of the
  plasma density of high-speed streams near the Sun to the strength of
  its source coronal hole. The rotation rates of the magnetic elements
  match the rotation rate of the coronal hole and is surprisingly similar
  to the differential rotation rate of active regions at low- and medium
  latitudes, suggesting they are rooted at similar deep layers. This
  also means that coronal holes do not show an abnormal rotation rate
  as suggested by various authors. Finally, by projecting the magnetic
  elements to AIA-171 and 193 filtergrams, we surprisingly find that the
  magnetic elements are not located in the darkest regions of coronal
  holes. Therefore, the vertical plasma outflow from magnetic funnels
  is probably not the primary reason why coronal holes appear as dark
  patches in EUV images. We conclude that magnetic elements are the
  basic building blocks of coronal holes which completely determine
  their magnetic properties.

---------------------------------------------------------
Title: Evolution of flux rope, CME and associated EUV wave in the
    10-Sep-2018 X8.2 event
Authors: Podladchikova, Tatiana; Veronig, Astrid M.; Dissauer, Karin;
   Temmer, Manuela; Seaton, Daniel B.; Long, David; Guo, Jingnan; Vršnak,
   Bojan; Harra, Louise; Kliem, Bernhard
2018csc..confE..38P    Altcode:
  We combine the high-cadence and large field-of-view EUV imagery of
  the Atmospheric Imaging Assembly (AIA) onboard SDO and the Solar
  Ultraviolet Imager (SUVI) onboard GOES-16 to study the origin and
  impulsive evolution of the fast CME that originated in the September
  10th 2017 X8.2 event as well as the initiation of the associated EUV
  wave. In the LASCO field-of-view, the CME reveals speeds &gt;3000
  km/s. In the low-to-mid corona, it shows a distinct bubble in the EUV
  imagery that reveals a significant lateral overexpansion. In addition,
  is also shows a distinct expanding cavity that is interpreted as
  manifestation of the flux rope driving the eruption. We present a method
  to automatically identify and segment the CME bubble in SUVI images and
  to derive its radial and lateral evolution up to about 2 solar radii,
  in terms of velocity and acceleration. These measurements are set into
  context with the evolution of the embedded flux rope/cavity observed by
  AIA. The observations show clear signatures of new poloidal flux added
  to the flux rope by magnetic reconnection in the current sheet beneath
  the eruptive structure, which is important for the high accelerations
  observed in this event. The radial propagation of the CME shell revealed
  a peak value of the acceleration of about 5.3 km/s2, whereas the lateral
  expansion reached a peak value of 10.1 km/s2, which is the largest value
  reported so far. The flux rope/cavity reveals a radial acceleration of
  6.7 km/s2 and lateral acceleration of 5.3 km/s2. We note that at this
  early evolution phase, the speed of the cavity/flux rope is higher
  than that of the CME bubble (front). The EUV wave associated with
  this eruption was observed by AIA, SUVI and STEREO-A EUVI, which had
  a separation angle with Earth of 128°, and the common field of view
  of the spacecraft was 52°. AIA and SUVI images above the solar limb
  reveal the initiation of the EUV wave by the accelerating flanks of
  the CME bubble, followed by detachment and propagation of the wave
  with a speed of 1100 km/s. The EUV wave shows a global propagation
  over the full hemisphere visible to Earth view as well as into the
  STEREO-A field-of-view. We study the propagation and kinematics of
  the direct as well as the various reflected and refracted EUV wave
  components on the solar sphere, finding speeds in the range from 370
  to 1010 km/s. Finally, we note that this EUV wave is also distinct as
  it reveals propagation and transmission through the polar coronal holes.

---------------------------------------------------------
Title: Studying the dynamics of coronal dimmings and their
    relationship to flares and coronal mass ejections
Authors: Dissauer, Karin; Veronig, Astrid M.; Temmer, Manuela;
   Podladchikova, Tatiana; Vanninathan, Kamalam
2018csc..confE..26D    Altcode:
  Coronal dimmings are observed as localized regions of reduced emission
  in the EUV and soft X-rays, interpreted as density depletions due to
  mass loss during the CME expansion. They contain crucial information on
  the evolution and early propagation phase of CMEs low in the corona. For
  a set of 62 dimming events, characteristic parameters, describing
  their dynamics, morphology, magnetic properties and the brightness
  evolution are derived, statistically analyzed and compared with basic
  flare and CME quantities. We use optimized multi-point observations,
  where the on-disk dimming evolution is studied in high-cadence
  SDO/AIA filtergrams and SDO/HMI line-of-sight magnetograms, while
  STEREO/EUVI, COR1 and COR2 data is used to measure the associated CME
  kinematics close to the limb with low projection effects. For 60% of
  the events we identified core dimmings, i.e. potential footpoints of
  the erupting CME structure. These regions contain 20% of the magnetic
  flux covering only 5% of the total dimming area. The majority of the
  total dimming area consists of secondary dimmings mapping overlying
  fields that are stretched during the eruption and closed down by
  magnetic reconnection, thus adding flux to the erupting structure
  via magnetic reconnection. This interpretation is supported by the
  high correlation between the magnetic fluxes of secondary dimmings
  and flare reconnection fluxes (c=0.63±0.08), the balance between
  positive and negative magnetic fluxes (c=0.83±0.04) within the total
  dimmings and the fact that for strong flares (&gt;M1.0) the flare
  reconnection and secondary dimming fluxes are roughly equal. The area
  of the total dimming, i.e. including both core and secondary dimmmings,
  its total brightness and the total unsigned magnetic flux show the
  highest correlations with the flare fluence (c&gt;0.7) and the CME
  mass (c&gt;0.6). Their corresponding time derivatives, describing
  the dimming dynamics, strongly correlate with the GOES flare class
  (c&gt;0.6). Events where high-cadence observations from STEREO are
  available show a moderate correlation between the area growth rate of
  the dimming and the maximum speed of the CME.

---------------------------------------------------------
Title: Multiple Satellite Analysis of the Earth's Thermosphere and
    Interplanetary Magnetic Field Variations Due to ICME/CIR Events
    During 2003-2015
Authors: Krauss, S.; Temmer, M.; Vennerstrom, S.
2018JGRA..123.8884K    Altcode: 2018arXiv181102999K
  We present a refined statistical analysis based on interplanetary
  coronal mass ejections (ICMEs) as well as corotating interaction regions
  (CIRs) for the time period 2003-2015 to estimate the impact of different
  solar wind types on the geomagnetic activity and the neutral density
  in the Earth's thermosphere. For the time-based delimitation of the
  events, we rely on the catalog maintained by Richardson and Cane and the
  corotating interaction region lists provided by S. Vennerstrom and Jian
  et al. (2011, https://doi.org/10.1007/s11207-011-9737-2). These archives
  are based on in situ measurements from the Advanced Composition Explorer
  and/or the Wind spacecraft. On this basis, we thoroughly investigated
  196 Earth-directed ICME and 195 CIR events. To verify the impact
  on the Earths thermosphere we determined neutral mass densities by
  using accelerometer measurements collected by the low-Earth-orbiting
  satellites Gravity Recovery and Climate Experiment and Challenging
  Minisatellite Payload. Subsequently, the atmospheric densities
  are related to characteristic ICME parameters. In this process a
  new calibration method has been examined. Since increased solar
  activity may lead to a decrease of the satellites orbital altitude
  we additionally assessed the orbital decay for each of the events
  and satellites. The influence of CIR events is in the same range of
  magnitude as the majority of the ICMEs (186 out of 196). Even though,
  the extended investigation period between 2011 and 2015 has a lack
  of extreme solar events the combined analysis reveals comparable
  correlation coefficients between the neutral densities and the various
  ICME and geomagnetic parameters (mostly &gt;0.85). The evaluation of
  orbit decay rates at different altitudes revealed a high dependency
  on the satellite actual altitude.

---------------------------------------------------------
Title: Hard X-ray Diagnostic of Proton Producing Solar Flares Compared
    to Other Emission Signatures
Authors: Miteva, Rositsa; Koleva, Kostadinka; Dechev, Momchil;
   Veronig, Astrid; Kozarev, Kamen; Temmer, Manuela; Dissauer, Karin;
   Duchlev, Peter
2018PASRB..18..117M    Altcode:
  We present results on the correlation analysis between the peak
  intensity of the in situ proton events from SOHO/ERNE instrument
  and the properties of their solar origin, solar flares and coronal
  mass ejections (CMEs). Starting at the RHESSI mission launch after
  2002, 70 flares well-observed in hard X-rays (HXRs) that are also
  accompanied with in situ proton events are selected. In addition
  to HXRs, flare emission at several other wavelengths, namely in the
  soft X-ray (SXR), ultraviolet (UV) and microwave (MW), is used. We
  calculated Pearson correlation coefficients between the proton peak
  intensities from one side, and, from another, the peak flare flux at
  various wavelengths or the speed of the accompanied CME. We obtain the
  highest correlations with the CME speed, with the SXR flare class and
  with MWs, lower ones with the SXR derivative, UV and 12-50 keV HXRs
  and the lowest correlation coefficients are obtained with the 50-300
  keV HXRs. Possible interpretations are discussed.

---------------------------------------------------------
Title: Three-phase Evolution of a Coronal Hole. II. The Magnetic Field
Authors: Heinemann, Stephan G.; Hofmeister, Stefan J.; Veronig,
   Astrid M.; Temmer, Manuela
2018ApJ...863...29H    Altcode: 2018arXiv180610052H
  We investigate the magnetic characteristics of a persistent coronal hole
  (CH) extracted from EUV imagery using Heliospheric and Magnetic Imager
  filtergrams over the period 2012 February-October. The magnetic field,
  its distribution, and the magnetic fine structure in the form of flux
  tubes (FTs) are analyzed in different evolutionary states of the CH. We
  find a strong linear correlation between the magnetic properties (e.g.,
  signed/unsigned magnetic field strength) and the area of the CH. As
  such, the evolutionary pattern in the magnetic field clearly follows
  a three-phase evolution (growing, maximum, and decaying) as found from
  EUV data (Part I). This evolutionary process is most likely driven by
  strong FTs with a mean magnetic field strength exceeding 50 G. During
  the maximum phase they entail up to 72% of the total signed magnetic
  flux of the CH, but only cover up to 3.9% of the total CH area, whereas
  during the growing and decaying phases, strong FTs entail 54%-60% of the
  signed magnetic flux and cover around 1%-2% of the CH’s total area. We
  conclude that small-scale structures of strong unipolar magnetic field
  are the fundamental building blocks of a CH and govern its evolution.

---------------------------------------------------------
Title: Filament Eruptions Associated with Flares, Coronal Mass
    Ejections and Solar Energetic Particle Events
Authors: Koleva, K.; Duchlev, P.; Dechev, M.; Miteva, R.; Kozarev,
   K.; Veronig, A.; Temmer, M.
2018simi.conf...19K    Altcode:
  We present analysis of three cases of filament eruptions (FEs)
  that occurred on 04 Aug 2011, 09 Nov 2011 and 05 Apr 2012 and their
  associations with flares as sources of solar energetic particles (SEPs)
  and coronal mass ejections. The associated FEs and SEP-related solar
  flares were selected by simultaneous observations in X-ray, EUV and
  radio wavelengths.

---------------------------------------------------------
Title: Statistics of Coronal Dimmings Associated with Coronal Mass
    Ejections. I. Characteristic Dimming Properties and Flare Association
Authors: Dissauer, K.; Veronig, A. M.; Temmer, M.; Podladchikova,
   T.; Vanninathan, K.
2018ApJ...863..169D    Altcode: 2018arXiv180705056D
  Coronal dimmings, localized regions of reduced emission in the
  extreme-ultraviolet and soft X-rays (SXRs), are interpreted as density
  depletions due to mass loss during the coronal mass ejection (CME)
  expansion. They contain crucial information on the early evolution
  of CMEs low in the corona. For 62 dimming events, characteristic
  parameters are derived, statistically analyzed, and compared with basic
  flare quantities. On average, coronal dimmings have a size of 2.15 ×
  10<SUP>10</SUP> km<SUP>2</SUP>, contain a total unsigned magnetic flux
  of 1.75 × 10<SUP>21</SUP> Mx, and show a total brightness decrease
  of -1.91 × 10<SUP>6</SUP> DN, which results in a relative decrease
  of ∼60% compared to the pre-eruption intensity level. Their main
  evacuation phase lasts for ∼50 minutes. The dimming area, the total
  dimming brightness, and the total unsigned magnetic flux show the
  highest correlation with the flare SXR fluence (c ≳ 0.7). Their
  corresponding time derivatives, describing the dimming dynamics,
  strongly correlate with the GOES flare class (c ≳ 0.6). For 60%
  of the events we identified core dimmings, i.e., signatures of an
  erupting flux rope. They contain 20% of the magnetic flux covering
  only 5% of the total dimming area. Secondary dimmings map overlying
  fields that are stretched during the eruption and closed down by
  magnetic reconnection, thus adding flux to the erupting flux rope
  via magnetic reconnection. This interpretation is supported by the
  strong correlation between the magnetic fluxes of secondary dimmings
  and flare reconnection fluxes (c = 0.63 ± 0.08), the balance between
  positive and negative magnetic fluxes (c = 0.83 ± 0.04) within the
  total dimmings, and the fact that for strong flares (&gt;M1.0) the
  reconnection and secondary dimming fluxes are roughly equal.

---------------------------------------------------------
Title: Dynamcis and magnetic properties in coronal holes using
    high-resolution multi-instrument solar observations
Authors: Krikova, K.; Utz, D.; Veronig, A.; Gömöry, P.; Hofmeister,
   S.; Temmer, M.
2018simi.conf...31K    Altcode:
  Using high-resolution solar observations from the Hinode Instruments
  SOT/SP, EIS and XRT as well as IRIS from a coronal hole on the 26th of
  September 2017, we are investigating the dynamics within the coronal
  hole visible on the specified date. Further satellite data support is
  given by full disc images from SDO with the AIA and HMI instruments. EIS
  and IRIS data provide us with crucial information about the plasma and
  energy flow from the Sun's chromosphere into the corona using the EUV
  and UV spectra and images. Investigating the magnetic configuration
  as well as the dynamics and changes within the coronal hole by using
  the SOT/SP data will give us additional crucial insights about the
  physical processes leading to the corresponding changes in the higher
  atmosphere. We compare the Hinode data with AIA and HMI data to get
  a firm comprehensive picture about the connection from high resolved
  photospheric fields and its dynamics within the higher layer. Within the
  timeframe of the analysed EIS dataset two microflare events associated
  with a solar jet were captured, originating inside the coronal hole
  under investigation. We believe that it is totally worthwhile to study
  these features in full detail as not so much attention was paid to high
  energy processes within coronal holes and their basic relationship to
  the harboring coronal hole and they show surprisingly high downflows
  in the Fe XII iron line (up to 140 km/s). In the current proceeding
  we will outline the state of the art of this investigation and give
  an overview of the further steps necessary. The mentioned data were
  obtained during a recent GREGOR campaign with the joint support of
  IRIS and Hinode (HOP 338).

---------------------------------------------------------
Title: Modeling the Evolution and Propagation of 10 September 2017
    CMEs and SEPs Arriving at Mars Constrained by Remote Sensing and In
    Situ Measurement
Authors: Guo, Jingnan; Dumbović, Mateja; Wimmer-Schweingruber,
   Robert F.; Temmer, Manuela; Lohf, Henning; Wang, Yuming; Veronig,
   Astrid; Hassler, Donald M.; Mays, Leila M.; Zeitlin, Cary; Ehresmann,
   Bent; Witasse, Olivier; Freiherr von Forstner, Johan L.; Heber, Bernd;
   Holmström, Mats; Posner, Arik
2018SpWea..16.1156G    Altcode: 2018arXiv180300461G
  On 10 September 2017, solar energetic particles originating from the
  active region 12673 produced a ground level enhancement at Earth. The
  ground level enhancement on the surface of Mars, 160 longitudinally
  east of Earth, observed by the Radiation Assessment Detector (RAD)
  was the largest since the landing of the Curiosity rover in August
  2012. Based on multipoint coronagraph images and the Graduated
  Cylindrical Shell model, we identify the initial 3-D kinematics of
  an extremely fast coronal mass ejection (CME) and its shock front,
  as well as another two CMEs launched hours earlier with moderate
  speeds. The three CMEs interacted as they propagated outward into the
  heliosphere and merged into a complex interplanetary CME (ICME). The
  arrival of the shock and ICME at Mars caused a very significant Forbush
  decrease seen by RAD only a few hours later than that at Earth, which
  was about 0.5 AU closer to the Sun. We investigate the propagation
  of the three CMEs and the merged ICME together with the shock, using
  the drag-based model and the WSA-ENLIL plus cone model constrained
  by the in situ observations. The synergistic study of the ICME and
  solar energetic particle arrivals at Earth and Mars suggests that to
  better predict potentially hazardous space weather impacts at Earth
  and other heliospheric locations for human exploration missions, it is
  essential to analyze (1) the eruption of the flare and CME at the Sun,
  (2) the CME kinematics, especially during their interactions, and
  (3) the spatially and temporally varying heliospheric conditions,
  such as the evolution and propagation of the stream interaction regions.

---------------------------------------------------------
Title: What can we learn from coronal dimmings about the early
    evolution of Earth-directed CMEs?
Authors: Dissauer, Karin; Podladchikova, Tatiana; Vanninathan, Kamalam;
   Veronig, Astrid; Temmer, Manuela
2018cosp...42E.846D    Altcode:
  Earth-directed coronal mass ejections (CMEs) are the main
  drivers for severe space weather events affecting the near-Earth
  environment. However, they allow the least accurate measurements of
  their properties due to strong projection effects and especially their
  early evolution is not well observed with traditional coronagraphs.The
  most distinct phenomena associated with CMEs are coronal dimmings,
  i.e. localized regions of reduced emission in the extreme-ultraviolet
  (EUV) and soft X-rays low in the corona. They are interpreted
  as density depletions due to mass loss or rapid expansion of the
  overlying corona during the CME lift off.We extract characteristic
  parameters describing the dynamics, morphology, magnetic properties
  and the brightness evolution of coronal dimming regions in order to
  obtain additional information on the initiation and early evolution of
  Earth-directed CMEs. To this aim, we developed an automatic dimming
  detection algorithm (based on logarithmic base-ratio images) that
  allows us also to distinguish between core and secondary dimming
  regions. Using this newly developed method, we extract the physical
  properties of 76 coronal dimming events in optimized multi-point
  observations and compare them with characteristic parameters describing
  their corresponding CMEs. The on-disk dimming evolution is studied
  using the high-cadence, multi-wavelengths data of SDO/AIA and the
  line-of-sight (LOS) magnetograms of SDO/HMI, while STEREO/EUVI, COR1 and
  COR2 data is used to measure the associated CME close to the limb with
  low projection effects.The impulsive phase of the dimming (i.e. main
  expansion phase of its area) starts co-temporal with the onset of the
  CME and the associated flare and the overall dimming region expands
  around locations that are identified as core dimming regions. On average
  this main evacuation phase lasts for about 50 minutes. For the majority
  of events, the total unsigned magnetic flux involved in the dimming
  regions is balanced and for selected events up to 30% of this flux
  results from the localized core dimming regions covering only ∼10% of
  the total dimming area. The size of the total dimming region, the total
  unsigned magnetic flux, as well as its intensity decrease are strongly
  correlated with the CME mass. Events where high-cadence observations
  from STEREO are available show in addition also a moderate correlations
  between the growth rate of the dimming and the maximum speed of the CME.

---------------------------------------------------------
Title: The September 2017 events and their imprints at Earth, Mars
    and STEREO-A
Authors: Guo, Jingnan; Wang, Yuming; Mays, M. Leila; Heber, Bernd;
   Holmstroem, Mats; Ehresmann, Bent; Olivier Witasse, .; Zeitlin,
   Cary; Taut, Andreas; Veronig, Astrid; Wimmer-Schweingruber, Robert;
   Dumbovic, Mateja; Lohf, Henning; Temmer, Manuela; Hassler, Donald M.;
   von Forstner, Johan Lauritz Freiherr
2018cosp...42E1321G    Altcode:
  During the declining phase of the current solar cycle, heliospheric
  activity has suddenly and drastically increased starting from a simple
  sunspot in Active Region (AR) 2673, which transformed into a complex
  region with three X-class flares accompanied by several Earth-directed
  Coronal Mass Ejections (CME) from 4th to 6th of September. Only a few
  days later, on 10th September, the same AR 2673 produced solar energetic
  particles (SEPs) which were registered as a ground level enhancement
  (GLE) at Earth and the biggest GLE on the surface of Mars as observed
  by the Radiation Assessment Detector (RAD) since the landing of the
  Curiosity rover in August 2012. Both Earth and Mars saw an impulsive and
  intense enhancement of the accelerated protons with energies larger
  than hundreds of MeV whereas STEREO-A, despite being at the back
  side of the event, detected gradually increasing fluxes of particles
  transported there across the heliospheric magnetic field. These high
  energy particles were mainly accelerated by the flares and shocks
  which were associated with three consecutive CMEs launched on 9th
  and 10th of September. Based on STEREO-A and SOHO coronograph images,
  we identified the initial three-dimensional kinematics of the three
  CMEs using the Graduated Cylindrical Shell (GCS) model. The first two
  CMEs had moderate launch speeds while the last one was extremely fast
  (larger than 2500 km/s at 20 solar radii). These three CMEs interacted
  as they propagated outwards into the heliosphere and the resulting
  complex interplanetary CME (ICME) together with its associated shock
  was highly likely related to the effective acceleration of particles
  at such high energies causing GLE at both Earth and Mars. The arrival
  of the ICME at Mars caused a very significant Forbush decrease seen
  by the Radiation Assessment Detector (RAD) on the surface of Mars
  and the arrival time is only a few hours later than that at Earth
  which is about 0.5 AU closer to the Sun than Mars. We investigated
  the interaction of three CMEs and propagation of the consequent ICME
  using the Drag Based Model (DBM) as well as the WSA-ENLIL plus cone
  model and the simulated results are compared with in-situ measurements
  at both Earth and Mars. The comparison shows that in order to better
  predict the ICME arrival and its potential space weather impact at
  Earth and other heliospheric locations, it is essential to 1) analyze
  the evolution of the ICME kinematics, especially during interactions
  of different CMEs and 2) better understand the spatially and temporally
  varying interplanetary conditions of the heliosphere.

---------------------------------------------------------
Title: Development of adaptive Kalman filter for solar wind forecast
Authors: Podladchikova, Tatiana; Veronig, Astrid; Temmer, Manuela;
   Hofmeister, Stefan
2018cosp...42E2698P    Altcode:
  Accurate solar wind modeling is important for predicting the arrival
  and geomagnetic response of high-speed solar wind streams as well as for
  modeling the transit of coronal mass ejections in interplanetary space
  and their impact at Earth. Data assimilation techniques combining the
  strength of models and observations provide a very useful tool for
  accurate solar wind forecasts. We develop a method to predict the
  solar wind speed at Earth 1-day ahead by using coronal hole areas
  derived from SDO AIA images in combination with in situ solar wind
  plasma and field data (speed, density, and magnetic field magnitude)
  from ACE and Wind spacecraft. To forecast the solar wind speed, we form
  a multidimensional linear regression model relating the solar wind speed
  one day ahead with the fractional coronal hole area observed three days
  before the current moment, as well as proton density, magnetic field
  magnitude, and solar wind speed at the current moment. One of the major
  concerns with such data assimilation scheme is that the regression
  coefficients do not remain constant and are time-varying. To avoid
  the fitting of regression coefficients to a particular situation,
  that can be changed in future, we develop an adaptive Kalman filter
  to create a dynamic linear regression for the 1-day ahead prediction
  of the solar wind speed. Testing the developed forecasting technique
  for the period 2010-2017, we obtain a correlation coefficient between
  the predicted and observed solar wind speed of 0.93, with an RMS error
  of prediction of 33 km/s. These results demonstrate that the proposed
  adaptive Kalman filter method significantly improves the quality of
  the solar wind forecasts and can be applied for reliable real-time
  warnings of the space weather conditions in the near-Earth environment.

---------------------------------------------------------
Title: CME acceleration and EUV wave kinematics for September 10th
    2017 event
Authors: Podladchikova, Tatiana; Dissauer, Karin; Veronig, Astrid;
   Temmer, Manuela; Seaton, Daniel
2018cosp...42E2697P    Altcode:
  On September 10th 2017 a large solar eruption, accompanied by an X8.2
  solar flare, from NOAA active region 12673 was observed on the Sun's
  western limb by the new Solar Ultraviolet Imager (SUVI) on the GOES-16
  spacecraft. We present a method to identify the CME bubble shape and
  to determine its radial and lateral acceleration. The large field of
  view of SUVI allows us to study the early impulsive CME acceleration
  up to 2 solar radii. The CME bubble reveals a fast evolution and
  strong overexpansion. The radial propagation of the CME revealed
  a peak value of the acceleration of about 4.8 km/s^{2}, whereas
  the lateral expansion reached a peak value of 8.9 km/s^{2}. The EUV
  wave associated with this eruption was observed by SUVI and STEREO-A,
  which had a separation angle with Earth of 128°, and the common field
  of view of both spacecraft was 52°. SUVI images above the solar limb
  reveal the initiation of the EUV wave by the accelerating flanks of the
  CME bubble, followed by detachment and propagation of the wave with
  a speed of 1100 km/s. Above the limb, the wave front can be observed
  as high as 0.7 solar radii. The EUV wave shows a global propagation
  over the full SUVI disk as well as into the STEREO-A field-of-view,
  and can be followed up to distances of about 1727 Mm from the source
  region. We study the propagation and kinematics of the direct as well
  as the various reflected and refracted EUV wave components on the solar
  sphere, finding speeds in the range from 370 to 1010 km/s. Finally,
  we note that this EUV wave is also distinct as it reveals propagation
  and transmission through a polar coronal hole.

---------------------------------------------------------
Title: Coronal mass ejections and space weather effects
Authors: Temmer, Manuela
2018cosp...42E3354T    Altcode:
  Earth-directed coronal mass ejections (CMEs), with their embedded
  magnetic fields and shocks ahead, compress and reconnect with the
  Earth's magnetic field and are the main drivers of strong geomagnetic
  storms. The impact of strong events may endanger critical ground-based
  infrastructure like power grids or disrupt communication and navigation
  systems. Due to such Space Weather effects, CMEs and related phenomena
  are an area of intense research interest. Important scientific
  knowledge could be achieved by closely monitoring and investigating
  the Sun-to-Earth "chain of action" of solar activity (evolution of
  surface magnetic fields, flares and CMEs), measurements of near-Earth
  space (in-situ plasma and magnetic field, energetic particles) and
  geomagnetic activity (response of the magnetosphere and different
  atmospheric layers down to ground-induced currents). This overview talk
  covers and discusses our recent understanding of the physical processes
  about the initiation and propagation of CMEs, their interaction with
  the solar wind and other ejecta, and consequences for Space Weather.

---------------------------------------------------------
Title: Three-phase Evolution of a Coronal Hole. I. 360° Remote
    Sensing and In Situ Observations
Authors: Heinemann, Stephan G.; Temmer, Manuela; Hofmeister, Stefan
   J.; Veronig, Astrid M.; Vennerstrøm, Susanne
2018ApJ...861..151H    Altcode: 2018arXiv180609495H
  We investigate the evolution of a well-observed, long-lived,
  low-latitude coronal hole (CH) over 10 solar rotations in the
  year 2012. By combining extreme ultraviolet (EUV) imagery from
  the Solar TErrestrial RElations Observatories (STEREO-A/B) and the
  Solar Dynamics Observatory (SDO), we are able to track and study the
  entire evolution of the CH having a continuous 360° coverage of the
  Sun. The remote sensing data are investigated together with in situ
  solar wind plasma and magnetic field measurements from STEREO-A/B, the
  Advanced Composition Explorer (ACE), and WIND. From this, we obtain
  how different evolutionary states of the CH as observed in the solar
  atmosphere (changes in EUV intensity and area) affect the properties
  of the associated high-speed stream measured at 1 au. Most distinctly
  pronounced for the CH area, three development phases are derived:
  (a) growing, (b) maximum, and (c) decaying phase. During these phases
  the CH area (a) increases over a duration of around three months from
  about 1 · 10<SUP>10</SUP> km<SUP>2</SUP> to 6 · 10<SUP>10</SUP>
  km<SUP>2</SUP>, (b) keeps a rather constant area for about one month of
  &gt;9 · 10<SUP>10</SUP> km<SUP>2</SUP>, and (c) finally decreases in
  the following three months below 1 · 10<SUP>10</SUP> km<SUP>2</SUP>
  until the CH cannot be identified anymore. The three phases manifest
  themselves also in the EUV intensity and in in situ measured solar wind
  proton bulk velocity. Interestingly, the three phases are related to
  a different range in solar wind speed variations, and we find for the
  growing phase a range of 460-600 km s<SUP>-1</SUP>, for the maximum
  phase 600-720 km s<SUP>-1</SUP>, and for the decaying phase a more
  irregular behavior connected to slow and fast solar wind speeds of
  350-550 km s<SUP>-1</SUP>.

---------------------------------------------------------
Title: Observations of the solar chromosphere with ALMA and comparison
    with theoretical models
Authors: Brajsa, Roman; Sudar, Davor; Skokic, Ivica; Benz, Arnold O.;
   Kuhar, Matej; Kobelski, Adam; Wedemeyer, Sven; White, Stephen M.;
   Ludwig, Hans-G.; Temmer, Manuela; Saar, Steven H.; Selhorst, Caius L.
2018csss.confE..37B    Altcode: 2018arXiv181207293B
  In this work we use solar observations with the ALMA radio telescope
  at the wavelength of 1.21 mm. The aim of the analysisis to improve
  understanding of the solar chromosphere, a dynamic layer in the
  solar atmosphere between the photosphere andcorona. The study has
  an observational and a modeling part. In the observational part
  full-disc solar images are analyzed.Based on a modied FAL atmospheric
  model, radiation models for various observed solar structures are
  developed. Finally, theobservational and modeling results are compared
  and discussed.

---------------------------------------------------------
Title: Ensemble Prediction of a Halo Coronal Mass Ejection Using
    Heliospheric Imagers
Authors: Amerstorfer, T.; Möstl, C.; Hess, P.; Temmer, M.; Mays,
   M. L.; Reiss, M. A.; Lowrance, P.; Bourdin, P. -A.
2018SpWea..16..784A    Altcode: 2017arXiv171200218A
  The Solar TErrestrial RElations Observatory (STEREO) and its
  heliospheric imagers (HIs) have provided us the possibility to enhance
  our understanding of the interplanetary propagation of coronal mass
  ejections (CMEs). HI-based methods are able to forecast arrival times
  and speeds at any target and use the advantage of tracing a CME's path
  of propagation up to 1 AU and beyond. In our study, we use the ELEvoHI
  model for CME arrival prediction together with an ensemble approach to
  derive uncertainties in the modeled arrival time and impact speed. The
  CME from 3 November 2010 is analyzed by performing 339 model runs
  that are compared to in situ measurements from lined-up spacecraft
  MErcury Surface, Space ENvironment, GEochemistry, and Ranging and
  STEREO-B. Remote data from STEREO-B showed the CME as halo event,
  which is comparable to an HI observer situated at L1 and observing an
  Earth-directed CME. A promising and easy approach is found by using
  the frequency distributions of four ELEvoHI output parameters, drag
  parameter, background solar wind speed, initial distance, and speed. In
  this case study, the most frequent values of these outputs lead to
  the predictions with the smallest errors. Restricting the ensemble
  to those runs, we are able to reduce the mean absolute arrival time
  error from 3.5 ± 2.6 to 1.6 ± 1.1 hr at 1 AU. Our study suggests that
  L1 may provide a sufficient vantage point for an Earth-directed CME,
  when observed by HI, and that ensemble modeling could be a feasible
  approach to use ELEvoHI operationally.

---------------------------------------------------------
Title: Forbush decrease model for expanding CMEs (ForbMod)
Authors: Dumbovic, Mateja; Möstl, Christian; Guo, Jingnan; Heber,
   Bernd; Vrsnak, Bojan; Temmer, Manuela
2018cosp...42E.917D    Altcode:
  Forbush decreases (FDs) can be used as one of the "signatures" of an
  ICME passage. An analytical diffusion-expansion FD model (ForbMod) was
  developed that is based on the widely used approach of an initially
  empty, closed magnetic structure (i.e. flux rope) that fills up
  slowly with particles by diffusion perpendicular to the magnetic
  field of the flux rope. In our approach the FD amplitude is not only
  determined by the diffusion process but also by the expansion of the
  flux rope. While the first process leads to a smaller amplitude the
  second one leads again to a larger effect. Remote CME observations
  and 3D reconstruction is used to constrain initial and boundary
  conditions. CME evolutionary properties are taken into account by
  incorporating the flux rope expansion. Several options of flux rope
  expansion are regarded as competing mechanism to diffusion, which can
  lead to different FD characteristics, and forward modelling is used
  to analyse flux rope expansion and further constrain the model. In
  testing the model, a number of spacecraft and planetary observation is
  utilised, including those by the Radiation Assessment Detector aboard
  the Mars Rover Curiosity. This project has received funding from the
  European Union's Horizon 2020 research and innovation programme under
  the Marie Sk_odowska-Curie grant agreement No 745782.

---------------------------------------------------------
Title: Modeling the evolution and propagation of the 2017 September
    9th and 10th CMEs and SEPs arriving at Mars constrained by
    remote-sensing and in-situ measurement
Authors: Guo, Jingnan; Dumbović, Mateja; Wimmer-Schweingruber,
   Robert F.; Temmer, Manuela; Lohf, Henning; Wang, Yuming; Veronig,
   Astrid; Hassler, Donald M.; Mays, Leila M.; Zeitlin, Cary; Ehresmann,
   Bent; Witasse, Olivier; von Forstner, Johan L. Freiherr; Heber, Bernd;
   Holmström, Mats; Posner, Arik
2018shin.confE..84G    Altcode:
  On 2017-09-10, solar energetic particles (SEPs) originating from the
  active region 12673 were registered as a ground level enhancement (GLE)
  at Earth and the biggest GLE on the surface of Mars as observed by the
  Radiation Assessment Detector (RAD) since the landing of the Curiosity
  rover in August 2012. Based on multi-point coronagraph im-

---------------------------------------------------------
Title: Ideas and plans for ISWAT clusters focused on propagation of
    transients through evolving ambient heliosphere and input to geospace
Authors: Temmer, Manuela
2018cosp...42E3353T    Altcode:
  Space Weather is an important issue of global matter, but needs
  coordinated efforts. Many international groups perform research
  on the propagation of transients and based on that develop Space
  Weather forecasting services. In order to avoid duplication and to
  efficiently improve the performance of currently available models, they
  need to become better visible and to undergo scientific peer-review
  qualification. iSWAT is an international, community driven effort
  and provides the required platform to challenge propagation models
  and to exchange experience with peers. iSWAT is also a network that
  fosters collaboration among interdisciplinary group members, like from
  geospace, that are potential users of propagation models. Coordinated
  international cooperation will offer new perspectives and will make
  models more efficient and progress them efficiently towards operational
  tools. Operational tools are not only meant to be used by (industrial)
  end-users, but particularly by peers in order to get a more complete
  understanding of the physical processes underlying CME propagation.

---------------------------------------------------------
Title: Drag-based ensemble model (DBEM)
Authors: Dumbovic, Mateja; Möstl, Christian; Mays, M. Leila; Vrsnak,
   Bojan; Veronig, Astrid; Salogovic, Jara; Piantschitsch, Isabell;
   Amerstorfer, Tanja; Temmer, Manuela; Sudar, Davor
2018cosp...42E.918D    Altcode:
  The drag-based model (DBM) for heliospheric propagation of ICMEs is
  a widely used simple analytical model which can predict ICME arrival
  time and speed at a given heliospheric distance (Vr_nak et al.,
  2013, SolPhys). It is based on the assumption that the heliospheric
  propagation of ICMEs, is solely under the influence of MHD drag,
  where ICME propagation is determined based on CME properties as
  well as the properties of the ambient solar wind. The current
  version of the DBM is operational as part of ESA's SSA programme
  (http://swe.ssa.esa.int/web/guest/graz-dbm-federated). The DBM takes
  into account the ICME geometry to track the whole leading edge of an
  ICME, it can estimate whether or not an ICME will reach the observer
  and calculate the transit time and impact speed. To estimate the
  uncertainty for a single event, Drag-Based Ensemble Model (DBEM) was
  developed (Dumbovic et al., 2018, ApJ) which utilizes an ensemble of the
  observation-based CME input and synthetic values of the ambient solar
  wind speed and drag parameter. Using multiple runs with different input
  parameters, distributions of predicted arrival times and speeds are
  obtained allowing to forecast the confidence in the likelihood of the
  ICME arrival. The DBEM was further developed to an on-line application
  to provide the real-time CME forecast, which is currently in a test
  phase, and will soon be a part of ESA-SSA Heliospheric Weather Expert
  Service Group (http://swe.ssa.esa.int/heliospheric-weather). We test
  the model and the on-line application using observations and compare
  the performance with other CME propagation models.

---------------------------------------------------------
Title: Predicting a CME arrival as observed from L1 by heliospheric
    imagers using ELEvoHI
Authors: Amerstorfer, Tanja; Moestl, Christian; Mays, M. Leila; Hess,
   Phillip; Temmer, Manuela; Reiss, Martin
2018cosp...42E..85A    Altcode:
  The Lagrangian point L5 is expected to be an ideal location for
  a future operational space weather observatory, already indicated
  by The Solar TErrestrial RElations Observatory (STEREO). STEREO has
  improved our understanding on the interplanetary (IP) evolution of
  coronal mass ejections (CMEs). Especially the wide-angle heliospheric
  imagers (HI) facilitated the development of a variety of methods for
  analyzing the evolution of CMEs through IP space. In this study,
  we present an ensemble forecast based on 339 model runs using the
  HI-based CME prediction tool ELEvoHI and test if an HI observer located
  at L1 may be an appropriate alternative (or supplement) to an L5 HI
  observatory. ELEvoHI, the ELlipse Evolution model (ELEvo) based on HI
  observations uses the benefits of different methods and observations. It
  provides the possibility to adjust the CME frontal shape (angular width,
  ellipse aspect ratio) and the direction of motion for each CME event
  individually. This information can be gained from Graduated Cylindrical
  Shell (GCS) flux-rope fitting within coronagraph images. Using the
  ELlipse Conversion (ELCon) method, the observed HI elongation angle
  is converted into a unit of distance, which reveals the kinematics
  (including the initial time, distance and speed) of the event. After
  fitting the time-distance profile of the CME using the drag-based
  equation of motion, where real-time in situ solar wind speed from 1
  AU is used as additional input, we obtain all input parameters needed
  to run a forecast using the ELEvo model and to predict arrival times
  and speeds at any target of interest in IP space. Here, we present a
  test on a slow CME event of 3 November 2010, in situ detected by the
  lined-up spacecraft MESSENGER and STEREO-B and remotely observed by
  STEREO-B/HI, i.e. it was a halo CME for STEREO-B. These conditions
  simulate an Earth-directed CME observed by HI located at L1. Our
  study suggests that L1 may provide a sufficient vantage point for an
  Earth-directed CME, when observed by HI, and that ensemble modeling
  could be a feasible approach to use ELEvoHI operationally.

---------------------------------------------------------
Title: An Analytical Diffusion-Expansion Model for Forbush Decreases
    Caused by Flux Ropes
Authors: Dumbović, Mateja; Heber, Bernd; Vršnak, Bojan; Temmer,
   Manuela; Kirin, Anamarija
2018ApJ...860...71D    Altcode: 2018arXiv180500916D
  We present an analytical diffusion-expansion Forbush decrease (FD)
  model ForbMod, which is based on the widely used approach of an
  initially empty, closed magnetic structure (i.e., flux rope) that
  fills up slowly with particles by perpendicular diffusion. The model
  is restricted to explaining only the depression caused by the magnetic
  structure of the interplanetary coronal mass ejection (ICME). We use
  remote CME observations and a 3D reconstruction method (the graduated
  cylindrical shell method) to constrain initial boundary conditions
  of the FD model and take into account CME evolutionary properties by
  incorporating flux rope expansion. Several flux rope expansion modes
  are considered, which can lead to different FD characteristics. In
  general, the model is qualitatively in agreement with observations,
  whereas quantitative agreement depends on the diffusion coefficient and
  the expansion properties (interplay of the diffusion and expansion). A
  case study was performed to explain the FD observed on 2014 May 30. The
  observed FD was fitted quite well by ForbMod for all expansion modes
  using only the diffusion coefficient as a free parameter, where the
  diffusion parameter was found to correspond to an expected range of
  values. Our study shows that, in general, the model is able to explain
  the global properties of an FD caused by a flux rope and can thus be
  used to help understand the underlying physics in case studies.

---------------------------------------------------------
Title: An Event-Based Verification Scheme for the Real-Time Flare
    Detection System at Kanzelhöhe Observatory
Authors: Pötzi, W.; Veronig, A. M.; Temmer, M.
2018SoPh..293...94P    Altcode:
  In the framework of the Space Situational Awareness program of the
  European Space Agency (ESA/SSA), an automatic flare detection system
  was developed at Kanzelhöhe Observatory (KSO). The system has been in
  operation since mid-2013. The event detection algorithm was upgraded
  in September 2017. All data back to 2014 was reprocessed using the new
  algorithm. In order to evaluate both algorithms, we apply verification
  measures that are commonly used for forecast validation. In order to
  overcome the problem of rare events, which biases the verification
  measures, we introduce a new event-based method. We divide the
  timeline of the Hα observations into positive events (flaring period)
  and negative events (quiet period), independent of the length of
  each event. In total, 329 positive and negative events were detected
  between 2014 and 2016. The hit rate for the new algorithm reached 96%
  (just five events were missed) and a false-alarm ratio of 17%. This
  is a significant improvement of the algorithm, as the original system
  had a hit rate of 85% and a false-alarm ratio of 33%. The true skill
  score and the Heidke skill score both reach values of 0.8 for the new
  algorithm; originally, they were at 0.5. The mean flare positions are
  accurate within ±1 heliographic degree for both algorithms, and the
  peak times improve from a mean difference of 1.7 ±2.9 minutes to 1.3
  ±2.3 minutes. The flare start times that had been systematically late
  by about 3 minutes as determined by the original algorithm, now match
  the visual inspection within −0.47 ±4.10 minutes.

---------------------------------------------------------
Title: "Chapter 15 - Coronal Holes Detection Using Supervised
    Classification
Authors: Delouille, Véronique; Hofmeister, Stefan J.; Reiss, Martin
   A.; Mampaey, Benjamin; Temmer, Manuela; Veronig, Astrid
2018mlts.book..365D    Altcode:
  We demonstrate the use of machine learning algorithms in combination
  with segmentation techniques in order to distinguish coronal holes and
  filaments in solar extreme ultraviolet (EUV) images recorded by the
  Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory. We
  used the Spatial Possibilistic Clustering Algorithm to prepare datasets
  of manually labeled coronal hole and filament channel regions present
  on the Sun during the time range 2010-16. By mapping the extracted
  regions from EUV observations onto Helioseismic and Magnetic Imager
  (HMI) line-of-sight magnetograms, we also include their magnetic
  characteristics. We computed average latitude, area, and shape measures
  from the segmented binary maps, as well as first-order and second-order
  texture statistics from the segmented regions in the EUV images and
  magnetograms. These attributes were used for data-mining investigations
  to identify the best rule for differentiating between coronal holes
  and filame! <P />nt channels, taking into account the imbalance in our
  dataset, which contains 1 filament channel for 15 coronal holes. We
  tested classifiers such as support vector machine (SVM), linear SVM,
  decision tree, k-nearest neighbors, as well as an ensemble classifier
  based on decision trees. The best performance in terms of true skill
  statistics is obtained with cost-sensitive learning, SVM classifiers,
  and when HMI attributes are included in the dataset.

---------------------------------------------------------
Title: A Comparative Study between a Failed and a Successful Eruption
    Initiated from the Same Polarity Inversion Line in AR 11387
Authors: Liu, Lijuan; Wang, Yuming; Zhou, Zhenjun; Dissauer, Karin;
   Temmer, Manuela; Cui, Jun
2018ApJ...858..121L    Altcode: 2018arXiv180400867L
  In this paper, we analyzed a failed and a successful eruption that
  initiated from the same polarity inversion line within NOAA AR 11387 on
  2011 December 25. They both started from a reconnection between sheared
  arcades, with distinct pre-eruption conditions and eruption details:
  before the failed one, the magnetic fields of the core region had a
  weaker non-potentiality; the external fields had a similar critical
  height for torus instability, and a similar local torus-stable region,
  but a larger magnetic flux ratio (of low corona and near-surface
  region) compared to the successful one. During the failed eruption,
  a smaller Lorentz force impulse was exerted on the outward ejecta;
  the ejecta had a much slower rising speed. Factors that might lead
  to the initiation of the failed eruption are identified: (1) a weaker
  non-potentiality of the core region, and a smaller Lorentz force impulse
  gave the ejecta a small momentum; (2) the large flux ratio, and the
  local torus-stable region in the corona provided strong confinements
  that made the erupting structure regain an equilibrium state.

---------------------------------------------------------
Title: Long-lasting injection of solar energetic electrons into
    the heliosphere
Authors: Dresing, N.; Gómez-Herrero, R.; Heber, B.; Klassen, A.;
   Temmer, M.; Veronig, A.
2018A&A...613A..21D    Altcode: 2018arXiv180204722D
  Context. The main sources of solar energetic particle (SEP) events are
  solar flares and shocks driven by coronal mass ejections (CMEs). While
  it is generally accepted that energetic protons can be accelerated by
  shocks, whether or not these shocks can also efficiently accelerate
  solar energetic electrons is still debated. In this study we present
  observations of the extremely widespread SEP event of 26 Dec 2013
  To the knowledge of the authors, this is the widest longitudinal
  SEP distribution ever observed together with unusually long-lasting
  energetic electron anisotropies at all observer positions. Further
  striking features of the event are long-lasting SEP intensity
  increases, two distinct SEP components with the second component mainly
  consisting of high-energy particles, a complex associated coronal
  activity including a pronounced signature of a shock in radio type-II
  observations, and the interaction of two CMEs early in the event. <BR
  /> Aims: The observations require a prolonged injection scenario not
  only for protons but also for electrons. We therefore analyze the data
  comprehensively to characterize the possible role of the shock for
  the electron event. <BR /> Methods: Remote-sensing observations of
  the complex solar activity are combined with in situ measurements of
  the particle event. We also apply a graduated cylindrical shell (GCS)
  model to the coronagraph observations of the two associated CMEs to
  analyze their interaction. <BR /> Results: We find that the shock alone
  is likely not responsible for this extremely wide SEP event. Therefore
  we propose a scenario of trapped energetic particles inside the CME-CME
  interaction region which undergo further acceleration due to the shock
  propagating through this region, stochastic acceleration, or ongoing
  reconnection processes inside the interaction region. The origin of
  the second component of the SEP event is likely caused by a sudden
  opening of the particle trap.

---------------------------------------------------------
Title: STEREO-A persistence model for solar wind speed forecasting
    and uncertainty assessment from the evolution of coronal holes
Authors: Temmer, Manuela; Hinterreiter, Jürgen; Reiss, Martin
2018EGUGA..20.3996T    Altcode:
  We present the concept of a persistence model to forecast the solar
  wind speed at 1 AU, using the advantage of multi-viewpoint satellite
  data. The model is based on STEREO in-situ measurements for satellite
  positions eastward of Earth, shifted forward by a variable time
  span according to the angle of the STEREO spacecraft with Earth (
  2-10 days). The STEREO persistence model is applied on the time range
  2008-2012 (STEREO-B) and 2017 (STEREO-A) and compared to a recurrence
  model based on ACE data forward shifted by a full rotation. In
  addition, the STEREO persistence model is modified by assessing the
  speed uncertainties that are caused by the evolution of coronal holes
  (CH). We derive the information on CH evolution by comparing CH areas
  extracted in EUV data from STEREO and Earth perspective. Compared to
  an ACE based persistence model, the performance of the new STEREO+CH
  persistence model which takes into account the evolution of coronal
  holes, is able to reduce the number of missed high-speed streams by
  about 23%, the false alarms by about 19%, and to increase the hit rate
  by about 12%.

---------------------------------------------------------
Title: Using Forbush decreases to derive the transit time of ICMEs
    propagating from 1 AU to Mars
Authors: von Forstner, Johan; Guo, Jingnan; Wimmer-Schweingruber,
   Robert F.; Hassler, Donald M.; Temmer, Manuela; Dumbović, Mateja;
   Jian, Lan K.; Appel, Jan K.; Čalogović, Jaša; Ehresmann, Bent;
   Heber, Bernd; Lohf, Henning; Posner, Arik; Vršnak, Bojan; Zeitlin,
   Cary J.
2018EGUGA..20.9306V    Altcode:
  The propagation of 15 interplanetary coronal mass ejections (ICMEs) from
  Earth's orbit (1 AU) to Mars (∼1.5 AU) has been studied with their
  propagation speed estimated from both measurements and simulations. The
  enhancement of magnetic fields related to ICMEs and their shock fronts
  cause the so-called Forbush decrease, which can be detected as a
  reduction of galactic cosmic ray (GCR) intensity measured on-ground
  or on a spacecraft. This effect can be used to detect the passage of
  ICMEs at various locations in the heliosphere, for example at Earth
  (using neutron monitors), the STEREO A and B spacecraft (HET) as well
  the on the surface of Mars using the Radiation Assessment Detector
  (RAD) instrument on the Mars Science Laboratory (MSL) rover. A set of
  ICME events has been selected during the periods when Earth (or STEREO
  A or B) and Mars locations were nearly aligned on the same side of the
  Sun in the ecliptic plane (so-called opposition phase). Such lineups
  allow us to estimate the ICMEs' transit times between 1 and 1.5 AU by
  determining the time delay between the corresponding Forbush decreases
  measured at each location. We investigate the evolution of the ICME
  propagation speeds before and after passing Earth's orbit and find
  that their deceleration due to interaction with the ambient solar
  wind may continue beyond 1 AU. We also find a substantial variance of
  the speed evolution among different events revealing the dynamic and
  diverse nature of eruptive solar events. Furthermore, the results are
  compared to simulation data obtained from two CME propagation models,
  namely the Drag-Based Model and ENLIL plus cone model.

---------------------------------------------------------
Title: Forbush decrease model for expanding CMEs (ForbMod)
Authors: Dumbovic, Mateja; Temmer, Manuela; Guo, Jingnan; Heber,
   Bernd; Möstl, Christian; Vrsnak, Bojan
2018EGUGA..2015396D    Altcode:
  The Project ForbMod aims to unravel how galactic cosmic rays are
  influenced by solar storms in the inner solar system (Sun to Mars)
  by developing a new model and utilizing a number of spacecraft and
  planetary observation, including those by the Radiation Assessment
  Detector aboard the Mars Rover Curiosity. The project focuses on
  Forbush decreases (FDs) in the galactic cosmic ray flux, which can
  be used as one of the "signatures" of an ICME passage. An analytical
  diffusion-expansion FD model was developed that is based on the
  widely used approach of an initially empty, closed magnetic structure
  (i.e. flux rope) that fills up slowly with particles by perpendicular
  diffusion. Remote CME observations and 3D reconstruction is used to
  constrain initial and boundary conditions. CME evolutionary properties
  are taken into account by incorporating the flux rope expansion. Several
  options of flux rope expansion are regarded as competing mechanism
  to diffusion, which can lead to different FD characteristics. This
  project has received funding from the European Union's Horizon 2020
  research and innovation programme under the Marie Skłodowska-Curie
  grant agreement No 745782.

---------------------------------------------------------
Title: Validation of the background solar wind modeled by EUHFORIA
Authors: Hinterreiter, Jürgen; Temmer, Manuela; Verbeke, Christine;
   Poedts, Stefaan; Pomoell, Jens; Magdalenic, Jasmina; Scolini, Camilla;
   Rodriguez, Luciano; Kilpua, Emili; Asvestari, Eleanna
2018EGUGA..20.6533H    Altcode:
  Nowadays, forecasting the arrival time and the geo-effectiveness of CMEs
  and the fast solar wind has become of increasing importance. For that
  reason, knowledge of the structure and propagation of the background
  solar wind is essential. The testing and validation of the performance
  of solar wind models is therefore important to assess their reliability
  and to further improve the models. This is done for the EUHFORIA
  (EUropean Heliospheric FORecasting Information Asset) model within
  the CCSOM (Constraining CMEs and Shocks by Observations and Modelling
  throughout the inner heliosphere) project [http://sidc.be/ccsom/]. We
  validate the modeled background solar wind by comparing the results to
  in-situ measurements, in order to make EUHFORIA ready for scientific
  exploitation and operational space weather purposes. For this several
  established test methods are applied on i) continuous variables of
  the solar wind plasma and magnetic field parameters (speed, density,
  pressure, Bz), and ii) binary variables based on specific events such
  as the arrival time and impact speed of solar wind high speed streams
  (HSS). We present first statistical results covering times of low
  (2008) and high (2012) solar activity.

---------------------------------------------------------
Title: The 3-Phase evolution of a long-lived low-latitude coronal
    hole.
Authors: Heinemann, Stephan; Temmer, Manuela; Hofmeister, Stefan;
   Veronig, Astrid; Vennerstrom, Susanne
2018EGUGA..20.6670H    Altcode:
  High speed solar wind streams (HSS) emanating from coronal holes, and
  associated stream interaction regions, may cause geomagnetic storms
  and deflect coronal mass ejections propagation in interplanetary
  space. By understanding the evolution and the relations between
  coronal holes and solar wind parameters, we increase our knowledge
  for improving space weather forecasts. We investigate the evolution
  of a persistent coronal hole using EUV data from STEREO-A/B and SDO
  over the timerange February 2012 -October 2012. Combined STEREO-SDO
  data enable a continuous observation of the CH covering 360° degrees
  over several rotations. Together with magnetic field measurements from
  SDO filtergrams and in-situ solar wind observations, we analyze during
  different evolutionary states of the CH, the solar surface properties
  of the CH (intensity, area, shape, magnetic flux) and its effects at
  1AU (solar wind speed). As a result we find an evolutionary pattern
  in most parameters, clearly showing a three-phase evolution (growing,
  maximum and decaying phase).

---------------------------------------------------------
Title: Hard X-ray, EUV, and radio signatures in relation to solar
    energetic particles
Authors: Koleva, Kostadinka; Miteva, Rositsa; Dechev, Momchil; Kozarev,
   Kamen; Veronig, Astrid; Temmer, Manuela
2018EGUGA..20.7408K    Altcode:
  In this report we present analysis of well-observed electromagnetic
  signatures related to solar energetic particles (SEPs). We selected
  cases with simultaneous observations in hard X-ray, EUV and radio
  wavelengths of the SEP-related solar flares and analyzed the properties
  of the emission (light curves, spectrum and temporal evolution). The
  non-thermal potential of solar flares is tested in terms of correlation
  studies between the particle intensities (protons and electrons) and
  the flare flux at various wavelengths. The results are compared with
  the outcomes when using GOES soft X-ray flare class. The solar origin
  of SEP events in terms of solar flares is discussed.

---------------------------------------------------------
Title: The September 2017 events and their imprints at Earth and Mars
Authors: Guo, Jingnan; Mays, Leila; Dumbovic, Mateja; Temmer, Manuela;
   Veronig, Astrid; Wimmer-Schweingruber, Robert; von Forstner, Johan
   Freiherr; Hassler, Donald; Heber, Bernd; Zeitlin, Cary; Ehresmann,
   Bent; Witasse, Oliver
2018EGUGA..2015655G    Altcode:
  During the declining phase of the current quiet solar cycle,
  heliospheric activity has suddenly and drastically increased starting
  from a simple sunspot in Active Region (AR) 2673, which transformed
  into a complex region with three X-flares accompanied by several
  Earth-directed Coronal Mass Ejections (CME) from 4th to 6th of
  September. Four days later, on 10th September, the same AR produced
  solar energetic particles (SEPs) which were registered as a ground
  level enhancement (GLE) at Earth and the biggest GLE on the surface
  of Mars as observed by the Radiation Assessment Detector (RAD) since
  the landing of the Curiosity rover in August 2012. Both Earth and Mars
  saw an impulsive and intense enhancement of the accelerated protons
  with energies larger than hundreds of MeV whereas STEREO-A, despite
  being at the back-side of the event, detected gradually increasing
  fluxes of particles transported there across the heliospheric magnetic
  field. Such high energetic particles were mainly accelerated by shocks
  associated with the CMEs also launched on 10th of September. Three CMEs
  with similar longitudinal launch directions (between Earth and Mars
  with the central axis approximately 100 degrees from Earth and 40-50
  degrees from Mars) can be identified based on STEREO-A and SOHO LASCO
  chronograph images. The first two had moderate launch speed while the
  last one had an extremely fast launch speed ( 2500 km/s). The merging
  and interactions of the three CMEs into an interplanetary CME (ICME)
  were very complex through the inner heliosphere and caused a very
  significant Forbush decrease at Mars three days later, even before the
  enhanced particle flux recovered to quiet-time level. The arrival of
  the ICME at Mars is only a few hours later than that at Earth, despite
  Mars being 0.5 AU further away from the Sun than Earth. This timing
  difference between the ICME arrival at Earth and Mars is likely due to
  (1) the earlier ICMEs from 4th and 6th which have considerably changed
  the interplanetary conditions and (2) the interaction of the ICME with
  a High Speed Stream structure passing by Mars. The 3D launch geometry
  and direction of the CMEs has been reconstructed based on the Graduated
  Cylindrical Shell (GCS) model and the subsequent ICME propagation has
  been performed using the WSA-ENLIL plus cone model, as well as the
  Drag Based Model (DBM) and CDPP propagation tool. Such modeled ICME
  arrivals at Earth and Mars are compared with in-situ measurements and
  the comparison shows that it is essential to consider the interactions
  of different CMEs as well as the spatially and temporally varying
  interplanetary conditions in order to better predict the ICME arrival
  at Earth and other planets.

---------------------------------------------------------
Title: Combining remote-sensing image data with in-situ measurements
    supported by modeling for Earth-affecting CME events
Authors: Temmer, Manuela; Thalmann, Julia; Dissauer, Karin; Veronig,
   Astrid; Tschernitz, Johannes; Hinterreiter, Jürgen; Rodriguez, Luciano
2018EGUGA..20.3999T    Altcode:
  We analyze the well observed flare-CME event from October 1, 2011
  and cover the complete chain of action - from the Sun to Earth. We
  study in detail the solar surface and atmosphere (SDO and ground-based
  instruments) associated to the flare/CME and also track the off-limb CME
  signatures in interplanetary space (STEREO-SoHO). This is complemented
  by surface magnetic field information and 3D coronal magnetic field
  modeling. From in-situ measurements (Wind), we extract the corresponding
  ICME characteristics. Results show that the flare reconnection flux is
  most probably a lower limit for estimating the magnetic flux within the
  flux rope as 1) magnetic reconnection processes were already ongoing
  before the start of the impulsive flare phase and 2) the dimming flux
  increased by more than 25% after the end of the flare, indicating that
  magnetic flux was still added to the flux rope after eruption. When
  comparing this to the in-situ axial magnetic flux of the magnetic cloud,
  we find that it is reduced by at least 75%, referring to substantial
  erosion in interplanetary space. Careful inspection of on-disk features
  associated with CMEs are essential for interpreting such scenarios.

---------------------------------------------------------
Title: Case study of July 2017 CMEs using modelling and
    multi-spacecraft observational approach
Authors: Dumbovic, Mateja; Guo, Jingnan; Temmer, Manuela
2018EGUGA..2015713D    Altcode:
  We present the analysis of several CMEs that erupted mid-July 2017
  from the same source region on the back side of the Sun as viewed from
  Earth. In our analysis, we use multi-instrument and multi-spacecraft
  measurements as well as different modeling approaches. We perform a
  3D reconstruction of each CME, to find their respective directions,
  geometry and kinematics. We employ WSA/ENLIL simulations and DBM
  propagation model to better understand their interplanetary evolution
  and associate them to signatures observed at STEREO-A and Mars. At Mars,
  a two-step Forbush decrease is observed with MSL/RAD July 24 2017. With
  the amplitude of more than 15% this is one of the largest Forbush
  decreases detected at Mars. At STEREO-A in situ ICME signatures are
  observed July 24/25 2017. This ICME shows a remarkably high magnetic
  field strength of 60 nT, probably related to the inability to expand
  due to interaction. This project has received funding from the European
  Union's Horizon 2020 research and innovation programme under the Marie
  Skłodowska-Curie grant agreement No 745782.

---------------------------------------------------------
Title: Tracking and validating ICMEs propagating towards Mars using
    STEREO Heliospheric Imagers combined with Forbush decreases detected
    by MSL/RAD
Authors: von Forstner, Johan; Guo, Jingnan; Temmer, Manuela; Dumbović,
   Mateja; Hassler, Donald M.
2018EGUGA..2014376V    Altcode:
  The enhancement of magnetic fields related to ICMEs and their shock
  fronts cause the so-called Forbush decrease, which can be detected as a
  reduction of galactic cosmic ray intensity (GCR) measured on-ground or
  on a spacecraft. Forbush decreases observed by the Radiation Assessment
  Detector (RAD) instrument onboard Mars Science Laboratory (MSL) on the
  surface of Mars as well as during its flight to Mars in 2011-2012 can
  be combined with observations at Earth and the two STEREO spacecraft to
  study the propagation of ICMEs up to Earth orbit and beyond to Mars. Our
  previous work (Freiherr von Forstner et al. 2017, JGR: Space Physics)
  considered the case where Earth (or STEREO A or B) and Mars were nearly
  forming a straight line with the Sun so that ICMEs can be observed in
  situ at both locations. We now also study periods where one or both
  of the STEREO spacecraft are positioned suitably to remotely track
  ICMEs directed towards Mars continuously with their coronagraph and
  heliospheric imaging instruments and compare the arrival signatures with
  the in situ detection of the Forbush decrease by MSL/RAD. By studying
  additional events in periods with this constellation, we enhance our
  investigation of the evolution of ICME propagation speeds through the
  inner heliosphere up to Mars.

---------------------------------------------------------
Title: Plasma Diagnostics of Coronal Dimming Events
Authors: Vanninathan, Kamalam; Veronig, Astrid M.; Dissauer, Karin;
   Temmer, Manuela
2018ApJ...857...62V    Altcode: 2018arXiv180206152V
  Coronal mass ejections are often associated with coronal dimmings,
  i.e., transient dark regions that are most distinctly observed in
  Extreme Ultra-violet wavelengths. Using Atmospheric Imaging Assembly
  (AIA) data, we apply Differential Emission Measure diagnostics to
  study the plasma characteristics of six coronal dimming events. In
  the core dimming region, we find a steep and impulsive decrease of
  density with values up to 50%-70%. Five of the events also reveal
  an associated drop in temperature of 5%-25%. The secondary dimming
  regions also show a distinct decrease in density, but less strong,
  decreasing by 10%-45%. In both the core and the secondary dimming the
  density changes are much larger than the temperature changes, confirming
  that the dimming regions are mainly caused by plasma evacuation. In
  the core dimming, the plasma density reduces rapidly within the first
  20-30 minutes after the flare start and does not recover for at least
  10 hr later, whereas the secondary dimming tends to be more gradual and
  starts to replenish after 1-2 hr. The pre-event temperatures are higher
  in the core dimming (1.7-2.6 MK) than in the secondary dimming regions
  (1.6-2.0 MK). Both core and secondary dimmings are best observed in
  the AIA 211 and 193 Å filters. These findings suggest that the core
  dimming corresponds to the footpoints of the erupting flux rope rooted
  in the AR, while the secondary dimming represents plasma from overlying
  coronal structures that expand during the CME eruption.

---------------------------------------------------------
Title: Coronal hole evolution from multi-viewpoint data as input
    for a STEREO solar wind speed persistence model
Authors: Temmer, Manuela; Hinterreiter, Jürgen; Reiss, Martin A.
2018JSWSC...8A..18T    Altcode: 2018arXiv180110213T
  We present a concept study of a solar wind forecasting method for Earth,
  based on persistence modeling from STEREO in situ measurements combined
  with multi-viewpoint EUV observational data. By comparing the fractional
  areas of coronal holes (CHs) extracted from EUV data of STEREO and
  SoHO/SDO, we perform an uncertainty assessment derived from changes
  in the CHs and apply those changes to the predicted solar wind speed
  profile at 1 AU. We evaluate the method for the time period 2008-2012,
  and compare the results to a persistence model based on ACE in situ
  measurements and to the STEREO persistence model without implementing
  the information on CH evolution. Compared to an ACE based persistence
  model, the performance of the STEREO persistence model which takes
  into account the evolution of CHs, is able to increase the number of
  correctly predicted high-speed streams by about 12%, and to decrease the
  number of missed streams by about 23%, and the number of false alarms by
  about 19%. However, the added information on CH evolution is not able
  to deliver more accurate speed values for the forecast than using the
  STEREO persistence model without CH information which performs better
  than an ACE based persistence model. Investigating the CH evolution
  between STEREO and Earth view for varying separation angles over
  ∼25-140° East of Earth, we derive some relation between expanding
  CHs and increasing solar wind speed, but a less clear relation for
  decaying CHs and decreasing solar wind speed. This fact most likely
  prevents the method from making more precise forecasts. The obtained
  results support a future L5 mission and show the importance and valuable
  contribution using multi-viewpoint data.

---------------------------------------------------------
Title: The Dependence of the Peak Velocity of High-Speed Solar Wind
    Streams as Measured in the Ecliptic by ACE and the STEREO satellites
    on the Area and Co-latitude of Their Solar Source Coronal Holes
Authors: Hofmeister, Stefan J.; Veronig, Astrid; Temmer, Manuela;
   Vennerstrom, Susanne; Heber, Bernd; Vršnak, Bojan
2018JGRA..123.1738H    Altcode: 2018arXiv180409579H
  We study the properties of 115 coronal holes in the time range
  from August 2010 to March 2017, the peak velocities of the
  corresponding high-speed streams as measured in the ecliptic at 1
  AU, and the corresponding changes of the Kp index as marker of their
  geoeffectiveness. We find that the peak velocities of high-speed streams
  depend strongly on both the areas and the co-latitudes of their solar
  source coronal holes with regard to the heliospheric latitude of
  the satellites. Therefore, the co-latitude of their source coronal
  hole is an important parameter for the prediction of the high-speed
  stream properties near the Earth. We derive the largest solar wind
  peak velocities normalized to the coronal hole areas for coronal holes
  located near the solar equator and that they linearly decrease with
  increasing latitudes of the coronal holes. For coronal holes located
  at latitudes ≳60°, they turn statistically to zero, indicating
  that the associated high-speed streams have a high chance to miss the
  Earth. Similarly, the Kp index per coronal hole area is highest for the
  coronal holes located near the solar equator and strongly decreases
  with increasing latitudes of the coronal holes. We interpret these
  results as an effect of the three-dimensional propagation of high-speed
  streams in the heliosphere; that is, high-speed streams arising from
  coronal holes near the solar equator propagate in direction toward and
  directly hit the Earth, whereas solar wind streams arising from coronal
  holes at higher solar latitudes only graze or even miss the Earth.

---------------------------------------------------------
Title: On the Detection of Coronal Dimmings and the Extraction of
    Their Characteristic Properties
Authors: Dissauer, K.; Veronig, A. M.; Temmer, M.; Podladchikova,
   T.; Vanninathan, K.
2018ApJ...855..137D    Altcode: 2018arXiv180203185D
  Coronal dimmings are distinct phenomena associated with coronal mass
  ejections (CMEs). The study of coronal dimmings and the extraction
  of their characteristic parameters help us to obtain additional
  information regarding CMEs, especially on the initiation and early
  evolution of Earth-directed CMEs. We present a new approach to detect
  coronal dimming regions based on a thresholding technique applied
  on logarithmic base-ratio images. Characteristic dimming parameters
  describing the dynamics, morphology, magnetic properties, and the
  brightness of coronal dimming regions are extracted by cumulatively
  summing newly dimmed pixels over time. It is also demonstrated how core
  dimming regions are identified as a subset of the overall identified
  dimming region. We successfully apply our method to two well-observed
  coronal dimming events. For both events, the core dimming regions are
  identified and the spatial evolution of the dimming area reveals the
  expansion of the dimming region around these footpoints. We also show
  that in the early impulsive phase of the dimming expansion the total
  unsigned magnetic flux involved in the dimming regions is balanced and
  that up to 30% of this flux results from the localized core dimming
  regions. Furthermore, the onset in the profile of the area growth rate
  is cotemporal with the start of the associated flares and in one case
  also with the fast rise of the CME, indicating a strong relationship
  of coronal dimmings with both flares and CMEs.

---------------------------------------------------------
Title: The Drag-based Ensemble Model (DBEM) for Coronal Mass Ejection
    Propagation
Authors: Dumbović, Mateja; Čalogović, Jaša; Vršnak, Bojan; Temmer,
   Manuela; Mays, M. Leila; Veronig, Astrid; Piantschitsch, Isabell
2018ApJ...854..180D    Altcode: 2018arXiv180107473D
  The drag-based model for heliospheric propagation of coronal mass
  ejections (CMEs) is a widely used analytical model that can predict
  CME arrival time and speed at a given heliospheric location. It is
  based on the assumption that the propagation of CMEs in interplanetary
  space is solely under the influence of magnetohydrodynamical drag,
  where CME propagation is determined based on CME initial properties
  as well as the properties of the ambient solar wind. We present
  an upgraded version, the drag-based ensemble model (DBEM), that
  covers ensemble modeling to produce a distribution of possible ICME
  arrival times and speeds. Multiple runs using uncertainty ranges for
  the input values can be performed in almost real-time, within a few
  minutes. This allows us to define the most likely ICME arrival times
  and speeds, quantify prediction uncertainties, and determine forecast
  confidence. The performance of the DBEM is evaluated and compared
  to that of ensemble WSA-ENLIL+Cone model (ENLIL) using the same
  sample of events. It is found that the mean error is ME = -9.7 hr,
  mean absolute error MAE = 14.3 hr, and root mean square error RMSE =
  16.7 hr, which is somewhat higher than, but comparable to ENLIL errors
  (ME = -6.1 hr, MAE = 12.8 hr and RMSE = 14.4 hr). Overall, DBEM and
  ENLIL show a similar performance. Furthermore, we find that in both
  models fast CMEs are predicted to arrive earlier than observed, most
  likely owing to the physical limitations of models, but possibly also
  related to an overestimation of the CME initial speed for fast CMEs.

---------------------------------------------------------
Title: A comparison of solar ALMA observations and model based
    predictions of the brightness temperature
Authors: Brajša, R.; Kuhar, M.; Benz, A. O.; Skokić, I.; Sudar,
   D.; Wedemeyer, S.; Báarta, M.; De Pontieu, B.; Kim, S.; Kobelski,
   A.; Shimojo, M.; White, S.; Yagoubov, P.; Yan, Y.; Ludwig, H. G.;
   Temmer, M.; Saar, S. H.; Selhorst, C. L.; Beuc, R.
2018CEAB...42....1B    Altcode:
  The new facility Atacama Large Millimeter/submillimeter Array (ALMA) is
  capable of observing the Sun in the wavelength range from 0.3 mm to 10
  mm with an unprecedented spatial, temporal and spectral resolution. The
  first aim of the present work is to identify different structures
  in the solar atmosphere (quiet Sun, active regions, filaments on the
  disc, and coronal holes) in a full disc solar ALMA image at 1.21 mm
  obtained on December 18, 2015 during a CSV-EOC campaign. It is compared
  with full disc solar images from the same day in the Hα line (Cerro
  Tololo Observatory, NISP), and at three EUV wavelengths (30.4 nm,
  21.1 nm, 17.1 nm; a composite SDO image). Positions of the quiet Sun
  areas, active regions, filaments on the disc, and coronal holes are
  identified in the ALMA image. To interpret solar observations with ALMA
  it is important to compare the measured and calculated intensities
  of various solar structures. So, the second aim of this work is to
  calculate the intensity (brightness temperature) for those structures
  (quiet Sun, active regions, filaments on the disc, and coronal holes)
  for a broad wavelength range (from 0.3 mm to 10 mm), closely related
  to that of the ALMA, and to compare the results with available
  ALMA observations. Thermal bremsstrahlung is the dominant radiation
  mechanism for explanation of the observed phenomena. A procedure for
  calculating the brightness temperature for a given wavelength and
  model atmosphere, which integrates the radiative transfer equation
  for thermal bremsstrahlung, is used. At the wavelength of 1.21 mm
  active regions appear as bright areas, while filaments on the disc and
  coronal holes are not discernible from the quiet Sun background. The
  models generally agree with the observed results: Active regions are
  bright primarily due to higher densities, filaments can appear bright,
  dark or not at all and coronal holes cannot be easily identified.

---------------------------------------------------------
Title: Small-scale dynamcis in a coronal-hole related to microflaring
    events
Authors: Krikova, K.; Utz, D.; Veronig, A.; Hofmeister, S.; Temmer,
   M.; Gömöry, P.; Holzknecht, L.
2018CEAB...42....8K    Altcode:
  Using high-resolution solar imagery and spectroscopy from the Hinode
  EIS and SDO instruments, we investigate the dynamics within a coronal
  hole observed on the 26th September 2017. Further data is given by
  full disc images from SDO with the AIA and HMI instruments. EIS
  spectra provide us with crucial information about the plasma and
  energy flows from the Sun's chromosphere into the corona. Within the
  timeframe of the analysed EIS dataset two microflares associated with a
  jet-like event were captured, originating inside the coronal hole under
  investigation. These two microflare events were analysed in the study at
  hand in detail. Such recurring solar transient events could contribute
  to the mass and energy input into the solar corona and also to the solar
  wind. Our analysis shows that microflare temperatures can reach up to
  3 MK with a hot component close to the reconnection site. Moreover an
  enhanced density at the microflare region was found. The obtained EIS
  ion line ratios suggest a density of up to 2.9 \cdot 10^{10} cm^{-3}.

---------------------------------------------------------
Title: 3D reconstruction and interplanetary expansion of the 2010
    April 3^{rd} CME
Authors: Rodari, M.; Dumbović, M.; Temmer, M.; Holzknecht, L.;
   Veronig, A.
2018CEAB...42...11R    Altcode: 2019arXiv190405611R
  We analyse the 2010 April 3^{rd} CME using spacecraft coronagraphic
  images at different vantage points (SOHO, STEREO-A and STEREO-B). We
  perform a 3D reconstruction of both the flux rope and shock using the
  Graduated Cylindrical Shell (GCS) model to calculate CME kinematic
  and morphologic parameters (e.g. velocity, acceleration, radius). The
  obtained results are fitted with empirical models describing the
  expansion of the CME radius in the heliosphere and compared with in
  situ measurements from Wind spacecraft: the CME is found to expand
  linearly towards Earth. Finally, we relate the event with decreases
  in the Galactic Cosmic Ray (GCR) Flux, known as Forbush decreases
  (FD), detected by EPHIN instrument onboard SOHO spacecraft. We use the
  analytical diffusion-expansion model (ForbMod) to calculate the magnetic
  field power law index, obtaining a value of ∼1.6, thus estimating
  a starting magnetic field of ∼0.01 G and an axial magnetic flux of
  ∼5 \cdot 10^{20} Mx at 15.6 R_⊙.

---------------------------------------------------------
Title: Using Forbush Decreases to Derive the Transit Time of ICMEs
    Propagating from 1 AU to Mars
Authors: Freiherr von Forstner, Johan L.; Guo, Jingnan;
   Wimmer-Schweingruber, Robert F.; Hassler, Donald M.; Temmer, Manuela;
   Dumbović, Mateja; Jian, Lan K.; Appel, Jan K.; Čalogović, Jaša.;
   Ehresmann, Bent; Heber, Bernd; Lohf, Henning; Posner, Arik; Steigies,
   Christian T.; Vršnak, Bojan; Zeitlin, Cary J.
2018JGRA..123...39F    Altcode: 2017arXiv171207301V
  The propagation of 15 interplanetary coronal mass ejections (ICMEs) from
  Earth's orbit (1 AU) to Mars (∼1.5 AU) has been studied with their
  propagation speed estimated from both measurements and simulations. The
  enhancement of magnetic fields related to ICMEs and their shock fronts
  causes the so-called Forbush decrease, which can be detected as a
  reduction of galactic cosmic rays measured on ground. We have used
  galactic cosmic ray (GCR) data from in situ measurements at Earth, from
  both STEREO A and STEREO B as well as GCR measurements by the Radiation
  Assessment Detector (RAD) instrument on board Mars Science Laboratory
  on the surface of Mars. A set of ICME events has been selected during
  the periods when Earth (or STEREO A or STEREO B) and Mars locations
  were nearly aligned on the same side of the Sun in the ecliptic plane
  (so-called opposition phase). Such lineups allow us to estimate the
  ICMEs' transit times between 1 and 1.5 AU by estimating the delay time
  of the corresponding Forbush decreases measured at each location. We
  investigate the evolution of their propagation speeds before and after
  passing Earth's orbit and find that the deceleration of ICMEs due to
  their interaction with the ambient solar wind may continue beyond 1
  AU. We also find a substantial variance of the speed evolution among
  different events revealing the dynamic and diverse nature of eruptive
  solar events. Furthermore, the results are compared to simulation data
  obtained from two CME propagation models, namely the Drag-Based Model
  and ENLIL plus cone model.

---------------------------------------------------------
Title: CME volume calculation from 3D GCS reconstruction
Authors: Holzknecht, L.; Temmer, M.; Dumbović, M.; Wellenzohn, S.;
   Krikova, K.; Heinemann, S. G.; Rodari, M.; Vršnak, B.; Veronig, A. M.
2018CEAB...42....3H    Altcode: 2019arXiv190411418H
  The mass evolution of a coronal mass ejection (CME) is an important
  parameter characterizing the drag force acting on a CME as it propagates
  through interplanetary space. Spacecraft measure in-situ plasma
  densities of CMEs during crossing events, but for investigating the
  mass evolution, we also need to know the CME geometry, more specific,
  its volume. Having derived the CME volume and mass from remote sensing
  data using 3D reconstructed CME geometry, we can calculate the CME
  density and compare it with in-situ proton density measurements near
  Earth. From that we may draw important conclusions on a possible
  mass increase as the CME interacts with the ambient solar wind in the
  heliosphere. In this paper we will describe in detail the method for
  deriving the CME volume using the graduated cylindrical shell (GCS)
  model tep[][see \ref{fig:GCSModel}]{thernisien06,thernisien09}. We show
  that, assuming self-similar expansion, one can derive the volume of the
  CME from two GCS parameters and that it furthermore can be expressed
  as a function of distance.

---------------------------------------------------------
Title: Plasma Diagnostics of Coronal Dimming Regions and Relation
    to Characteristic CME Parameters
Authors: Veronig, A.; Vanninathan, K.; Dissauer, K.; Temmer, M.
2017AGUFMSH52B..08V    Altcode:
  Coronal Mass Ejections (CMEs) are often associated with coronal
  dimmings, i.e. transient dark regions in the solar corona that are most
  prominently observed at Extreme Ultra-violet (EUV) wavelengths. Coronal
  dimmings are thought to be a result of the evacuation of mass related to
  the erupting CME structure. Using data from the six EUV channels of the
  Atmospheric Imaging Assembly (AIA) onboard SDO, we apply Differential
  Emission Measure (DEM) diagnostics, to study the plasma characteristics
  of on-disk coronal dimming regions. We analysed in detail seven
  coronal dimming events associated with CMEs distributed over a speed
  range from 300 to 1250 km/s. We derived the weighted emission measure,
  density and temperature as a function of time for both the core and
  the secondary dimming regions. In the core dimming regions, the plasma
  parameters reached a minimum within about 30 min after the CME onset,
  whereas the secondary dimming regions tend to show a more gradual
  evolution. For most of the events, the values of these parameters
  remained low within the core dimming region for the entire duration
  of this study ( 10 hrs after the flare) while the secondary dimming
  region showed a gradual increase after 1-2 hrs indicating refilling of
  these regions with plasma. The emission measure decrease in the core
  dimming region was found to lie in the range from 60-90%, the density
  decrease from 35-70% and the temperature decrease from 5-30%. In the
  secondary dimming region, the decreases of the plasma parameters derived
  are smaller. In addition, we performed a statistical analysis of 76
  dimming events during the time range 2010 - 2012, which were observed
  on-disk by SDO and close to the limb by at least one of the two STEREO
  spacecraft. Characteristic parameters of the early CME dynamics (initial
  velocity, peak acceleration, mass and initiation height) are derived
  and compared with decisive coronal dimming parameters like the magnetic
  flux involved, the area, the area growth rate and the intensity drop
  in the dimming region. The findings of our study are discussed with
  respect to the different coronal structures involved in the dimming
  regions and how they relate to decisive parameters of the CME.

---------------------------------------------------------
Title: Long-lasting solar energetic electron injection during the
    26 Dec 2013 widespread SEP event
Authors: Dresing, N.; Klassen, A.; Temmer, M.; Gomez-Herrero, R.;
   Heber, B.; Veronig, A.
2017AGUFMSH33C..03D    Altcode:
  The solar energetic particle (SEP) event on 26 Dec 2013 was detected
  all around the Sun by the two STEREO spacecraft and close-to-Earth
  observers. While the two STEREOs were separated by 59 degrees and
  situated at the front side of the associated large coronal event,
  it was a backside-event for Earth. Nevertheless, significant and
  long-lasting solar energetic electron anisotropies together with long
  rise times were observed at all three viewpoints, pointing to an
  extended electron injection. Although the CME-driven shock appears
  to account for the SEP event at a first glance a more detailed view
  reveals a more complex scenario: A CME-CME interaction takes place
  during the very early phase of the SEP event. Furthermore, four hours
  after the onset of the event, a second component is measured at all
  three viewpoints on top of the first SEP increase, mainly consisting
  of high energy particles. We find that the CME-driven shock alone
  can hardly account for the observed SEP event in total but a trapping
  scenario together with ongoing particle acceleration is more likely.

---------------------------------------------------------
Title: Multi-spacecraft observations of ICMEs propagating beyond
    Earth orbit during MSL/RAD flight and surface phases
Authors: von Forstner, J.; Guo, J.; Wimmer-Schweingruber, R. F.;
   Hassler, D.; Temmer, M.; Vrsnak, B.; Čalogović, J.; Dumbovic, M.;
   Lohf, H.; Appel, J. K.; Heber, B.; Steigies, C. T.; Zeitlin, C.;
   Ehresmann, B.; Jian, L. K.; Boehm, E.; Boettcher, S. I.; Burmeister,
   S.; Martin-Garcia, C.; Brinza, D. E.; Posner, A.; Reitz, G.; Matthiae,
   D.; Rafkin, S. C.; weigle, G., II; Cucinotta, F.
2017AGUFMSH53A2543V    Altcode:
  The propagation of interplanetary coronal mass ejections (ICMEs)
  between Earth's orbit (1 AU) and Mars ( 1.5 AU) has been studied
  with their propagation speed estimated from both measurements and
  simulations. The enhancement of the magnetic fields related to ICMEs
  and their shock fronts cause so-called Forbush decreases, which can
  be detected as a reduction of galactic cosmic rays measured on-ground
  or on a spacecraft. We have used galactic cosmic ray (GCR) data from
  in-situ measurements at Earth, from both STEREO A and B as well
  as the GCR measurement by the Radiation Assessment Detector (RAD)
  instrument onboard Mars Science Laboratory (MSL) on the surface of
  Mars as well as during its flight to Mars in 2011-2012. A set of ICME
  events has been selected during the periods when Earth (or STEREO A
  or B) and MSL locations were nearly aligned on the same side of the
  Sun in the ecliptic plane (so-called opposition phase). Such lineups
  allow us to estimate the ICMEs' transit times between 1 AU and the
  MSL location by estimating the delay time of the corresponding Forbush
  decreases measured at each location. We investigate the evolution of
  their propagation speeds after passing Earth's orbit and find that the
  deceleration of ICMEs due to their interaction with the ambient solar
  wind continues beyond 1 AU. The results are compared to simulation data
  obtained from two CME propagation models, namely the Drag-Based Model
  (DBM) and the WSA-ENLIL plus cone model.

---------------------------------------------------------
Title: The Analytical Diffusion-Expansion Model for Forbush Decreases
    Caused by Flux Ropes
Authors: Dumbovic, M.; Temmer, M.
2017AGUFMSH13C2492D    Altcode:
  Identification and tracking of interplanetary coronal mass ejections
  (ICMEs) throughout the heliosphere is a growingly important aspect
  of space weather research. One of the "signatures" of ICME passage
  is the corresponding Forbush decrease (FD), a short term decrease
  in the galactic cosmic ray flux. These depressions are observed at
  the surface of the Earth for over 50 years, by several spacecraft in
  interplanetary space in the past couple of decades, and recently also
  on Mars' surface with Curiosity rover. In order to use FDs as ICME
  signatures efficiently, it is important to model ICME interaction
  with energetic particles by taking into account ICME evolution
  and constraining the model with observational data. We present an
  analytical diffusion-expansion FD model ForbMod which is based on
  the widely used approach of the initially empty, closed magnetic
  structure (i.e. flux rope) which fills up slowly with particles by
  perpendicular diffusion. The model is restricted to explain only
  the depression caused by the magnetic structure of the ICME and not
  of the associated shock. We use remote CME observations and a 3D
  reconstruction method (the Graduated Cylindrical Shell method) to
  constrain initial and boundary conditions of the FD model and take
  into account CME evolutionary properties by incorporating flux rope
  expansion. Several options of flux rope expansion are regarded as
  the competing mechanism to diffusion which can lead to different FD
  characteristics. This project has received funding from the European
  Union's Horizon 2020 research and innovation programme under the Marie
  Skłodowska-Curie grant agreement No 745782.

---------------------------------------------------------
Title: Presentation of the project "An investigation of the early
    stages of solar eruptions - from remote observations to energetic
    particles"
Authors: Kozarev, Kamen; Veronig, Astrid; Duchlev, Peter; Koleva,
   Kostadinka; Dechev, Momchil; Miteva, Rositsa; Temmer, Manuela;
   Dissauer, Karin
2017ses..conf...63K    Altcode:
  Coronal mass ejections (CMEs), one of the most energetic manifestations
  of solar activity, are complex events, which combine multiple related
  phenomena occurring on the solar surface, in the extended solar
  atmosphere (corona), as well as in interplanetary space. We present
  here an outline of a new collaborative project between scientists
  from the Bulgarian Academy of Sciences (BAS), Bulgaria and the
  University of Graz, Austria. The goal of the this research project
  is to answer the following questions: 1) What are the properties of
  erupting filaments, CMEs, and CME-driven shock waves near the Sun, and
  of associated solar energetic particle (SEP) fluxes in interplanetary
  space? 2) How are these properties related to the coronal acceleration
  of SEPs? To achieve the scientific goals of this project, we will use
  remote solar observations with high spatial and temporal resolution to
  characterize the early stages of coronal eruption events in a systematic
  way - studying the pre-eruptive behavior of filaments and flares during
  energy build-up, the kinematics and morphology of CMEs and compressive
  shock waves, and the signatures of high energy non-thermal particles
  in both remote and in situ observations.

---------------------------------------------------------
Title: The Causes of Quasi-homologous CMEs
Authors: Liu, Lijuan; Wang, Yuming; Liu, Rui; Zhou, Zhenjun; Temmer,
   M.; Thalmann, J. K.; Liu, Jiajia; Liu, Kai; Shen, Chenglong; Zhang,
   Quanhao; Veronig, A. M.
2017ApJ...844..141L    Altcode: 2017arXiv170608878L
  In this paper, we identified the magnetic source locations of 142
  quasi-homologous (QH) coronal mass ejections (CMEs), of which 121
  are from solar cycle (SC) 23 and 21 from SC 24. Among those CMEs, 63%
  originated from the same source location as their predecessor (defined
  as S-type), while 37% originated from a different location within the
  same active region as their predecessor (defined as D-type). Their
  distinctly different waiting time distributions, peaking around 7.5 and
  1.5 hr for S- and D-type CMEs, suggest that they might involve different
  physical mechanisms with different characteristic timescales. Through
  detailed analysis based on nonlinear force-free coronal magnetic field
  modeling of two exemplary cases, we propose that the S-type QH CMES
  might involve a recurring energy release process from the same source
  location (by magnetic free energy replenishment), whereas the D-type
  QH CMEs can happen when a flux tube system is disturbed by a nearby CME.

---------------------------------------------------------
Title: Erratum: “The Confined X-class Flares of Solar Active Region
2192” (<A href="http://doi.org/10.1088/2041-8205/801/2/L23">2015,
    ApJL, 801, L23</A>)
Authors: Thalmann, J. K.; Su, Y.; Temmer, M.; Veronig, A. M.
2017ApJ...844L..27T    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: On Flare-CME Characteristics from Sun to Earth Combining
    Remote-Sensing Image Data with In Situ Measurements Supported
    by Modeling
Authors: Temmer, Manuela; Thalmann, Julia K.; Dissauer, Karin;
   Veronig, Astrid M.; Tschernitz, Johannes; Hinterreiter, Jürgen;
   Rodriguez, Luciano
2017SoPh..292...93T    Altcode: 2017arXiv170300694T
  We analyze the well-observed flare and coronal mass ejection (CME)
  from 1 October 2011 (SOL2011-10-01T09:18) covering the complete chain of
  effects - from Sun to Earth - to better understand the dynamic evolution
  of the CME and its embedded magnetic field. We study in detail the
  solar surface and atmosphere associated with the flare and CME using the
  Solar Dynamics Observatory (SDO) and ground-based instruments. We also
  track the CME signature off-limb with combined extreme ultraviolet
  (EUV) and white-light data from the Solar Terrestrial Relations
  Observatory (STEREO). By applying the graduated cylindrical shell
  (GCS) reconstruction method and total mass to stereoscopic STEREO-SOHO
  (Solar and Heliospheric Observatory) coronagraph data, we track
  the temporal and spatial evolution of the CME in the interplanetary
  space and derive its geometry and 3D mass. We combine the GCS and
  Lundquist model results to derive the axial flux and helicity of
  the magnetic cloud (MC) from in situ measurements from Wind. This is
  compared to nonlinear force-free (NLFF) model results, as well as to
  the reconnected magnetic flux derived from the flare ribbons (flare
  reconnection flux) and the magnetic flux encompassed by the associated
  dimming (dimming flux). We find that magnetic reconnection processes
  were already ongoing before the start of the impulsive flare phase,
  adding magnetic flux to the flux rope before its final eruption. The
  dimming flux increases by more than 25% after the end of the flare,
  indicating that magnetic flux is still added to the flux rope after
  eruption. Hence, the derived flare reconnection flux is most probably a
  lower limit for estimating the magnetic flux within the flux rope. We
  find that the magnetic helicity and axial magnetic flux are lower in
  the interplanetary space by ∼ 50% and 75%, respectively, possibly
  indicating an erosion process. A CME mass increase of 10% is observed
  over a range of ∼4 -20 R<SUB>⊙</SUB>. The temporal evolution of
  the CME-associated core-dimming regions supports the scenario that
  fast outflows might supply additional mass to the rear part of the CME.

---------------------------------------------------------
Title: Sunward-propagating Solar Energetic Electrons inside Multiple
    Interplanetary Flux Ropes
Authors: Gómez-Herrero, Raúl; Dresing, Nina; Klassen, Andreas;
   Heber, Bernd; Temmer, Manuela; Veronig, Astrid; Bučík, Radoslav;
   Hidalgo, Miguel A.; Carcaboso, Fernando; Blanco, Juan J.; Lario, David
2017ApJ...840...85G    Altcode:
  On 2013 December 2 and 3, the SEPT and STE instruments on board
  STEREO-A observed two solar energetic electron events with unusual
  sunward-directed fluxes. Both events occurred during a time
  interval showing typical signatures of interplanetary coronal mass
  ejections (ICMEs). The electron timing and anisotropies, combined with
  extreme-ultraviolet solar imaging and radio wave spectral observations,
  are used to confirm the solar origin and the injection times of the
  energetic electrons. The solar source of the ICME is investigated using
  remote-sensing observations and a three-dimensional reconstruction
  technique. In situ plasma and magnetic field data combined with
  energetic electron observations and a flux-rope model are used to
  determine the ICME magnetic topology and the interplanetary electron
  propagation path from the Sun to 1 au. Two consecutive flux ropes
  crossed the STEREO-A location and each electron event occurred inside
  a different flux rope. In both cases, the electrons traveled from the
  solar source to 1 au along the longest legs of the flux ropes still
  connected to the Sun. During the December 2 event, energetic electrons
  propagated along the magnetic field, while during the December 3 event
  they were propagating against the field. As found by previous studies,
  the energetic electron propagation times are consistent with a low
  number of field line rotations N &lt; 5 of the flux rope between the
  Sun and 1 au. The flux rope model used in this work suggests an even
  lower number of rotations.

---------------------------------------------------------
Title: The February 15 2011 CME-CME interaction and possibly
    associated radio emission
Authors: Magdalenic, Jasmina; Temmer, Manuela; Krupar, Vratislav;
   Marque, Christophe; Veronig, Astrid; Eastwood, Jonathan
2017EGUGA..19.9850M    Altcode:
  On February 15, 2011 a particular, continuum-like radio emission was
  observed by STEREO WAVES and WIND WAVES spacecraft. The radio event
  appeared to be associated with the complex interaction of two coronal
  mass ejections (CMEs) successively launched (February 14 and February
  15) from the same active region. Although the CME-CME interaction was
  widely studied (e.g. Temmer et al., 2014, Maricic et al., 2014, Mishra
  &amp; Srivastava, 2014) none of the analyses confirmed an association
  with the continuum-like radio emission. The usual method of establishing
  temporal coincidence of radio continuum and a CME-CME interaction is not
  applicable in this event due to a complex and long-lasting interaction
  of the CMEs. Therefore, we performed radio triangulation studies (see
  also Magdalenic et al., 2014) which provided us with the 3D source
  positions of the radio emission. Comparison of the positions of radio
  sources and the reconstructed positions of the interacting CMEs, shows
  that the source position of the continuum-like radio emission is about
  0.5 AU away from the interacting CMEs. We can therefore concluded that,
  in this event, the continuum-like emission is not the radio signature
  of the CME-CME interaction.

---------------------------------------------------------
Title: The Interaction of Successive Coronal Mass Ejections: A Review
Authors: Lugaz, Noé; Temmer, Manuela; Wang, Yuming; Farrugia,
   Charles J.
2017SoPh..292...64L    Altcode: 2016arXiv161202398L
  We present a review of the different aspects associated with the
  interaction of successive coronal mass ejections (CMEs) in the corona
  and inner heliosphere, focusing on the initiation of series of CMEs,
  their interaction in the heliosphere, the particle acceleration
  associated with successive CMEs, and the effect of compound events
  on Earth's magnetosphere. The two main mechanisms resulting in the
  eruption of series of CMEs are sympathetic eruptions, when one eruption
  triggers another, and homologous eruptions, when a series of similar
  eruptions originates from one active region. CME - CME interaction may
  also be associated with two unrelated eruptions. The interaction of
  successive CMEs has been observed remotely in coronagraphs (with the
  Large Angle and Spectrometric Coronagraph Experiment - LASCO - since
  the early 2000s) and heliospheric imagers (since the late 2000s), and
  inferred from in situ measurements, starting with early measurements
  in the 1970s. The interaction of two or more CMEs is associated with
  complex phenomena, including magnetic reconnection, momentum exchange,
  the propagation of a fast magnetosonic shock through a magnetic ejecta,
  and changes in the CME expansion. The presence of a preceding CME a
  few hours before a fast eruption has been found to be connected with
  higher fluxes of solar energetic particles (SEPs), while CME - CME
  interaction occurring in the corona is often associated with unusual
  radio bursts, indicating electron acceleration. Higher suprathermal
  population, enhanced turbulence and wave activity, stronger shocks,
  and shock - shock or shock - CME interaction have been proposed as
  potential physical mechanisms to explain the observed associated SEP
  events. When measured in situ, CME - CME interaction may be associated
  with relatively well organized multiple-magnetic cloud events, instances
  of shocks propagating through a previous magnetic ejecta or more complex
  ejecta, when the characteristics of the individual eruptions cannot
  be easily distinguished. CME - CME interaction is associated with some
  of the most intense recorded geomagnetic storms. The compression of a
  CME by another and the propagation of a shock inside a magnetic ejecta
  can lead to extreme values of the southward magnetic field component,
  sometimes associated with high values of the dynamic pressure. This can
  result in intense geomagnetic storms, but can also trigger substorms and
  large earthward motions of the magnetopause, potentially associated with
  changes in the outer radiation belts. Future in situ measurements in
  the inner heliosphere by Solar Probe+ and Solar Orbiter may shed light
  on the evolution of CMEs as they interact, by providing opportunities
  for conjunction and evolutionary studies.

---------------------------------------------------------
Title: Understanding CMEs using plasma diagnostics of the related
    dimmings
Authors: Vanninathan, Kamalam; Veronig, Astrid; Gomory, Peter;
   Dissauer, Karin; Temmer, Manuela; Hannah, Iain; Kontar, Eduard
2017EGUGA..19.1571V    Altcode:
  Coronal Mass Ejections (CMEs) are often associated with dimmings that
  are well observed in Extreme Ultra-violet (EUV) wavelengths. Such
  dimmings are suggested to represent the evacuation of mass that is
  carried out by CMEs and are a unique and indirect means to study CME
  properties. While Earth-directed CMEs (on-disk CMEs) are difficult to
  observe due to the bright background solar disk and projection effects,
  their corresponding dimmings are clearly discernible and ideally suited
  for analysis. Using data from the 6 EUV channels of Solar Dynamics
  Observatory/Atmospheric Imaging Assembly for Differential Emission
  Measure (DEM) diagnostics, we determine the plasma characteristics of
  the dimming region. These data are well suited for this kind of study
  due to the good temperature ranges covered by the multiple passbands
  of the instrument. We analyse 7 on-disk and 5 off-limb events and
  derive the weighted density and temperature as a function of time,
  from the DEMs. From such an analysis we differentiate 2 types of dimming
  regions: core and secondary dimmings. Core dimmings often occur in pairs
  lying on either sides of the active region and in opposite polarity
  regions while the secondary dimming is more extended. In both the
  regions the derived plasma parameters reach a minimum within 30-60
  min after the flare. For each event the core dimming region shows
  a higher decrease in density and temperature than the corresponding
  secondary dimming regions. The values of these parameters remains low
  within the core dimming region for the entire duration of this study
  ( 10 hrs after the flare) while the secondary dimming region starts to
  show a gradual increase after 1-2 hrs. We also use spectroscopic data
  from Hinode/Extreme-Ultraviolet Imaging Spectrometer to differentiate
  core and secondary dimming regions. We find that the Fe XIII 202 Å
  line shows double component profiles within the core dimming region
  with strong blueshifts of 100 km/s while the secondary dimming region
  has weak upflows of 10 km/s. We conclude that the core dimming region
  corresponds to footpoints of the erupting flux rope from where there
  is continuous strong upflowing plasma for at least 10 hrs after the
  flare, while the secondary dimming region begins to refill within 1-2
  hrs. These measurements can be used to deduce information about the
  mass of on-disk CMEs where white light measurements can fail. We also
  confirm that the dimmings are mainly caused by density decrease and
  not temperature changes. DEM analysis is a strong tool to decipher
  CME properties from dimming regions.

---------------------------------------------------------
Title: Statistical analysis on how CME and SIR/CIR events effect
    the geomagnetic activity and the Earth's thermosphere
Authors: Krauss, Sandro; Temmer, Manuela; Edl, Martina; Veronig, Astrid
2017EGUGA..1915251K    Altcode:
  In order to estimate the impact of different types of solar wind
  on the geomagnetic activity and the neutral density in the Earth's
  thermosphere, we present a comprehensive statistical analysis based on
  interplanetary coronal mass ejections (ICME) covering the time range
  from July 2003 - 2016 and stream interaction as well as corotating
  interaction regions (SIR/CIR) from July 2003 - December 2009. In
  general, geomagnetic storms induced by CIR are characterized by lower
  energy input compared to ICME induced storms but a significantly longer
  duration time due to a long-term negative Bz component in the magnetic
  cloud region. Regarding the time of occurrence of ICME events, we rely
  on the catalogue maintained by Richardson and Cane. For the period of
  investigation more than 250 Earth-directed CME events are listed. All
  of them have been measured in situ by plasma and field instruments on
  board the ACE spacecraft. The arrival times of SIRs/CIRs are taken from
  the catalogue maintained by Lan Jian based on ACE and Wind in-situ
  measurements. From this list, we extracted 98 SIR/CIR events, from
  which the minimum Bz component is determined within a time window of
  36 hours starting at the arrival of the SIR/CIR (same procedure as for
  ICMEs). Accordingly, the peak in Earth's neutral density is determined
  in the same time window. The densities itself are estimated by using
  accelerometer measurements collected by the Gravity Recovery And Climate
  Experiment (GRACE) satellites and subsequently related to various
  geomagnetic indices (e.g. SYM-H, Polar cap, a-indices, ...) as well
  as characteristic CME parameters like the impact speed, the southward
  magnetic field strength Bz and resultant derivatives. We find high
  correlations (cc=0.9) between the CME characteristic (except the impact
  speed) and the thermospheric density enhancements as well as with most
  of the geomagnetic indices. However, considering only weaker ICME events
  (Bz up to -20nT) a lower correlation must be conceded. The same holds
  true for SIR/CIR events, as both cover compressed sheath regions with
  turbulent magnetic field. The absolute density increases for SIR/CIR
  induced storms is in the order of 1.7E-12kg/m3 for Bz values ranging
  from -4 to -19nT, with a related correlation coefficient of -0.41.

---------------------------------------------------------
Title: Quantification of disturbance periods of solar wind speed in
    interplanetary space due to coronal mass ejections
Authors: Temmer, Manuela; Reiss, Martin A.; Nikolic, Ljubomir;
   Hofmeister, Stefan J.; Veronig, Astrid M.
2017EGUGA..19.1940T    Altcode:
  Interplanetary space is characteristically structured mainly by
  high-speed solar wind streams emanating from coronal holes and transient
  disturbances such as coronal mass ejections (CMEs). While high-speed
  solar wind streams pose a continuous outflow, CMEs abruptly disrupt
  the rather steady structure causing large deviations from the quiet
  solar wind conditions. We present a quantification of the duration of
  disturbed conditions (preconditioning) for interplanetary space caused
  by CMEs by investigating the plasma speed component of the solar wind
  and the impact of in situ detected CMEs (ICMEs), compared to different
  background solar wind models (ESWF, WSA, persistence model) for the
  time range 2011-2015. We obtain for periods within an ICME interval
  an increase of 18-32% above the expected quiet Sun background and for
  the period of 2 days after the ICME an increase of 9-24%. The total
  duration of enhanced deviations is about 3 and up to 6 days after the
  ICME start, which is much longer than the average duration of an ICME
  disturbance itself (about 1.3 days), concluding that interplanetary
  space needs about 2-5 days to recover from the impact of ICMEs. The
  obtained results have strong implications for studying CME propagation
  behavior and also for space weather forecasting.

---------------------------------------------------------
Title: Testing ElEvoHI on a multi-point in situ detected Coronal
    Mass Ejection
Authors: Amerstorfer, Tanja; Möstl, Christian; Hess, Phillip; Mays,
   M. Leila; Temmer, Manuela
2017EGUGA..19.7675A    Altcode:
  The Solar TErrestrial RElations Observatory (STEREO) has provided us
  a deep insight into the interplanetary propagation of coronal mass
  ejections (CMEs). Especially the wide-angle heliospheric imagers (HI)
  enabled the development of a multitude of methods for analyzing the
  evolution of CMEs through interplanetary (IP) space. Methods able
  to forecast arrival times and speeds at Earth (or other targets)
  use the advantage of following a CME's path of propagation up to 1
  AU. However, these methods were not able to reduce today's errors
  in arrival time forecasts to less than ±6 hours, arrival speeds are
  mostly overestimated by some 100 km s-1. One reason for that is the
  assumption of constant propagation speed, which is clearly incorrect
  for most CMEs—especially for those being faster than the ambient
  solar wind. ElEvoHI, the Ellipse Evolution model (ElEvo) based on HI
  observations, is a new prediction tool, which uses the benefits of
  different methods and observations. It provides the possibility to
  adjust the CME frontal shape (angular width, ellipse aspect ratio)
  and the direction of motion for each CME event individually. This
  information can be gained from Graduated Cylindrical Shell (GCS)
  flux-rope fitting within coronagraph images. Using the Ellipse
  Conversion (ElCon) method, the observed HI elongation angle is
  converted into a unit of distance, which reveals the kinematics of the
  event. After fitting the time-distance profile of the CME using the
  drag-based equation of motion, where real-time in situ solar wind speed
  from 1 AU is used as additional input, we receive all input parameters
  needed to run a forecast using the ElEvo model and to predict arrival
  times and speeds at any target of interest in IP space. Here, we present
  a test on a slow CME event of 3 November 2010, in situ detected by
  the lined-up spacecraft MESSENGER and STEREO Behind. We gain the shape
  of the CME front from a cut of the 3D GCS CME shape with the ecliptic
  plane, resulting in an almost ideal ElEvoHI forecast of arrival time
  and speed at 1 AU.

---------------------------------------------------------
Title: Flare-CME characteristics from Sun to Earth combining
    observations and modeling
Authors: Temmer, Manuela; Thalmann, Julia K.; Dissauer, Karin;
   Veronig, Astrid M.; Tschernitz, Johannes; Hinterreiter, Jürgen;
   Rodriguez, Luciano
2017EGUGA..19.1942T    Altcode:
  We analyze the well observed flare-CME event from October 1, 2011
  (SOL2011-10-01T09:18) covering the complete chain of action - from
  Sun to Earth - for a better understanding of the dynamic evolution
  of the CME and its embedded magnetic field. We study in detail the
  solar surface and atmosphere from SDO and ground-based instruments
  associated to the flare-CME and also track the CME signature offlimb
  from combined EUV and white-light data with STEREO. By applying 3D
  reconstruction techniques (GCS, total mass) to stereoscopic STEREO-SoHO
  coronagraph data, we track the temporal and spatial evolution of the
  CME in interplanetary space and derive its geometry and 3D-mass. We
  combine the GCS and Lundquist model results to derive the axial flux
  and helicity of the MC from in situ measurements (Wind). This is
  compared to nonlinear force-free (NLFF) model results as well as to
  the reconnected magnetic flux derived from the flare ribbons (flare
  reconnection flux) and the magnetic flux encompassed by the associated
  dimming (dimming flux). We find that magnetic reconnection processes
  were already ongoing before the start of the impulsive flare phase,
  adding magnetic flux to the flux rope before its final eruption. The
  dimming flux increases by more than 25% after the end of the flare,
  indicating that magnetic flux is still added to the flux rope after
  eruption. Hence, the derived flare reconnection flux is most probably a
  lower limit for estimating the magnetic flux within the flux rope. We
  obtain that the magnetic helicity and axial magnetic flux are reduced
  in interplanetary space by ∼50% and 75%, respectively, possibly
  indicating to an erosion process. A mass increase of 10% for the CME
  is observed over the distance range from about 4-20 Rs. The temporal
  evolution of the CME associated core dimming regions supports the
  scenario that fast outflows might supply additional mass to the rear
  part of the CME.

---------------------------------------------------------
Title: Preconditioning of Interplanetary Space Due to Transient
    CME Disturbances
Authors: Temmer, M.; Reiss, M. A.; Nikolic, L.; Hofmeister, S. J.;
   Veronig, A. M.
2017ApJ...835..141T    Altcode: 2016arXiv161206080T
  Interplanetary space is characteristically structured mainly by
  high-speed solar wind streams emanating from coronal holes and transient
  disturbances such as coronal mass ejections (CMEs). While high-speed
  solar wind streams pose a continuous outflow, CMEs abruptly disrupt
  the rather steady structure, causing large deviations from the quiet
  solar wind conditions. For the first time, we give a quantification
  of the duration of disturbed conditions (preconditioning) for
  interplanetary space caused by CMEs. To this aim, we investigate
  the plasma speed component of the solar wind and the impact of in
  situ detected interplanetary CMEs (ICMEs), compared to different
  background solar wind models (ESWF, WSA, persistence model) for the
  time range 2011-2015. We quantify in terms of standard error measures
  the deviations between modeled background solar wind speed and observed
  solar wind speed. Using the mean absolute error, we obtain an average
  deviation for quiet solar activity within a range of 75.1-83.1 km
  s<SUP>-1</SUP>. Compared to this baseline level, periods within
  the ICME interval showed an increase of 18%-32% above the expected
  background, and the period of two days after the ICME displayed an
  increase of 9%-24%. We obtain a total duration of enhanced deviations
  over about three and up to six days after the ICME start, which is
  much longer than the average duration of an ICME disturbance itself
  (∼1.3 days), concluding that interplanetary space needs ∼2-5 days
  to recover from the impact of ICMEs. The obtained results have strong
  implications for studying CME propagation behavior and also for space
  weather forecasting.

---------------------------------------------------------
Title: Characteristics of Low-latitude Coronal Holes near the Maximum
    of Solar Cycle 24
Authors: Hofmeister, Stefan J.; Veronig, Astrid; Reiss, Martin A.;
   Temmer, Manuela; Vennerstrom, Susanne; Vršnak, Bojan; Heber, Bernd
2017ApJ...835..268H    Altcode: 2017arXiv170202050H
  We investigate the statistics of 288 low-latitude coronal holes
  extracted from SDO/AIA-193 filtergrams over the time range of
  2011 January 01-2013 December 31. We analyze the distribution of
  characteristic coronal hole properties, such as the areas, mean AIA-193
  intensities, and mean magnetic field densities, the local distribution
  of the SDO/AIA-193 intensity and the magnetic field within the coronal
  holes, and the distribution of magnetic flux tubes in coronal holes. We
  find that the mean magnetic field density of all coronal holes under
  study is 3.0 ± 1.6 G, and the percentaged unbalanced magnetic flux
  is 49 ± 16%. The mean magnetic field density, the mean unsigned
  magnetic field density, and the percentaged unbalanced magnetic flux of
  coronal holes depend strongly pairwise on each other, with correlation
  coefficients cc &gt; 0.92. Furthermore, we find that the unbalanced
  magnetic flux of the coronal holes is predominantly concentrated in
  magnetic flux tubes: 38% (81%) of the unbalanced magnetic flux of
  coronal holes arises from only 1% (10%) of the coronal hole area,
  clustered in magnetic flux tubes with field strengths &gt;50 G (10
  G). The average magnetic field density and the unbalanced magnetic
  flux derived from the magnetic flux tubes correlate with the mean
  magnetic field density and the unbalanced magnetic flux of the overall
  coronal hole (cc &gt; 0.93). These findings give evidence that the
  overall magnetic characteristics of coronal holes are governed by the
  characteristics of the magnetic flux tubes.

---------------------------------------------------------
Title: 70 Years of Sunspot Observations at the Kanzelhöhe
Observatory: Systematic Study of Parameters Affecting the Derivation
    of the Relative Sunspot Number
Authors: Pötzi, Werner; Veronig, Astrid M.; Temmer, Manuela;
   Baumgartner, Dietmar J.; Freislich, Heinrich; Strutzmann, Heinz
2016SoPh..291.3103P    Altcode: 2016SoPh..tmp...43P; 2015arXiv151200270P
  The Kanzelhöhe Observatory (KSO) was founded during World War II by
  the Deutsche Luftwaffe (German Airforce) as one station of a network
  of observatories that were set up to provide information on solar
  activity in order to better assess the actual conditions of the Earth's
  ionosphere in terms of radio-wave propagation. Solar observations
  began in 1943 with photographs of the photosphere and drawings of
  sunspots, plage regions, and faculae, as well as patrol observations
  of the solar corona. At the beginning, all data were sent to Freiburg
  (Germany). After WW II, international cooperation was established and
  the data were sent to Zurich, Paris, Moscow, and Greenwich. Relative
  sunspot numbers have been derived since 1944. The agreement between
  relative sunspot numbers derived at KSO and the new International
  Sunspot Number (ISN) (SILSO World Data Center in International Sunspot
  Number Monthly Bulletin and online catalogue, 1945 - 2015) lies within
  ≈10 % . However, revisiting the historical data, we also find periods
  with larger deviations. The reasons for the deviations were twofold: On
  the one hand, a major instrumental change took place during which the
  instrument was relocated and modified. On the other hand, a period of
  frequent replacements of personnel caused significant deviations; this
  clearly shows the importance of experienced observers. In the long term,
  the instrumental improvements led to better image quality. Additionally,
  we find a long-term trend towards better seeing conditions that began
  in 2000.

---------------------------------------------------------
Title: Kinematical properties of coronal mass ejections
Authors: Temmer, M.
2016AN....337.1010T    Altcode: 2016arXiv160301398T
  Coronal mass ejections (CMEs) are the most dynamic phenomena in our
  solar system. They abruptly disrupt the continuous outflow of solar
  wind by expelling huge clouds of magnetized plasma into interplanetary
  space with velocities enabling to cross the Sun-Earth distance within
  a few days. Earth-directed CMEs may cause severe geomagnetic storms
  when their embedded magnetic fields and the shocks ahead compress
  and reconnect with the Earth's magnetic field. The transit times and
  impacts in detail depend on the initial CME velocity, size, and mass,
  as well as on the conditions and coupling processes with the ambient
  solar wind flow in interplanetary space. The observed CME parameters
  may be severely affected by projection effects and the constant changing
  environmental conditions are hard to derive. This makes it difficult to
  fully understand the physics behind CME evolution, preventing to do a
  reliable forecast of Earth-directed events. This short review focusing
  on observational data, shows recent methods which were developed to
  derive the CME kinematical profile for the entire Sun-Earth distance
  range as well as studies which were performed to shed light on the
  physical processes that CMEs encounter when propagating from Sun
  to Earth.

---------------------------------------------------------
Title: Projection Effects in Coronal Dimmings and Associated EUV
    Wave Event
Authors: Dissauer, K.; Temmer, M.; Veronig, A. M.; Vanninathan, K.;
   Magdalenić, J.
2016ApJ...830...92D    Altcode: 2016arXiv160705961D
  We investigate the high-speed (v &gt; 1000 km s<SUP>-1</SUP>)
  extreme-ultraviolet (EUV) wave associated with an X1.2 flare and coronal
  mass ejection (CME) from NOAA active region 11283 on 2011 September
  6 (SOL2011-09-06T22:12). This EUV wave features peculiar on-disk
  signatures in particular, we observe an intermittent “disappearance”
  of the front for 120 s in Solar Dynamics Observatory (SDO)/AIA 171,
  193, 211 Å data, whereas the 335 Å filter, sensitive to hotter
  plasmas (T ∼ 2.5 MK), shows a continuous evolution of the wave
  front. The eruption was also accompanied by localized coronal dimming
  regions. We exploit the multi-point quadrature position of SDO and
  STEREO-A, to make a thorough analysis of the EUV wave evolution, with
  respect to its kinematics and amplitude evolution and reconstruct
  the SDO line-of-sight (LOS) direction of the identified coronal
  dimming regions in STEREO-A. We show that the observed intensities
  of the dimming regions in SDO/AIA depend on the structures that are
  lying along their LOS and are the combination of their individual
  intensities, e.g., the expanding CME body, the enhanced EUV wave,
  and the CME front. In this context, we conclude that the intermittent
  disappearance of the EUV wave in the AIA 171, 193, and 211 Å filters,
  which are channels sensitive to plasma with temperatures below ∼2
  MK is also caused by such LOS integration effects. These observations
  clearly demonstrate that single-view image data provide us with limited
  insight to correctly interpret coronal features.

---------------------------------------------------------
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: Exceptions to the rule: the X-flares of AR 2192 Lacking
    Coronal Mass Ejections
Authors: Thalmann, J. K.; Su, Y.; Temmer, M.; Veronig, A. M.
2016ASPC..504..203T    Altcode:
  NOAA Active region (AR) 2192, that was present on the Sun in October
  2014, was the largest region which occurred since November 1990
  (see Figure 1). The huge size accompanied by a very high activity
  level, was quite unexpected as it appeared during the unusually weak
  solar cycle 24. Nevertheless, the AR turned out to be one of the most
  prolific flaring ARs of cycle 24. It produced in total 6 X, 29 M, 79
  C flares during its disk passage from October 18-29, 2014 (see Figure
  2). Surprisingly, all flares greater than GOES class M5 and X were
  confined, i.e. had no coronal mass ejections (CME) associated. All
  the flare events had some obvious similarity in morphology, as they
  were located in the core of the AR and revealed only minor separation
  motion away from the neutral line but a large initial separation of
  the conjugate flare ribbons. In the paper by Thalmann et al. (2015)
  we describe the series of flares and give details about the confined
  X1.6 flare event from October 22, 2014 as well as the single eruptive
  M4.0 flare event from October 24, 2014. The study of the X1.6 flare
  revealed a large initial separation of flare ribbons together with
  recurrent flare brightenings, which were related to two episodes of
  enhanced hard X-ray emission as derived from RHESSI observations. This
  suggests that magnetic field structures connected to specific regions
  were repeatedly involved in the process of reconnection and energy
  release. Opposite to the central location of the sequence of confined
  events within the AR, a single eruptive (M4.0) event occurred on
  the outskirt of the AR in the vicinity of open magnetic fields. Our
  investigations revealed a predominantly north-south oriented magnetic
  system of arcade fields overlying the AR that could have preserved
  the magnetic arcade to erupt, and consequently kept the energy release
  trapped in a localized volume of magnetic field high up in the corona
  (as supported by the absence of a lateral motion of the flare ribbons
  and the recurrent brightenings within them). We conclude that the
  background magnetic field configuration is an essential parameter
  for deriving the "eruptiveness" of flare events. Sun et al. (2015)
  supports this conclusion and derived for this AR a quite slow
  decay of the strength of the overlying magnetic field (decay index;
  see Török &amp; Kliem 2005). Interestingly, our magnetic field
  modellings revealed no flux rope inherent to the AR, indicating that
  further investigations are needed. In a recent paper by Veronig $
  Polanec (2015), who investigated in more detail the X-flares using
  also ground-based observations in Hα from Kanzelhöhe Observatory
  (Pötzi et al. 2015), it was shown that such confined events could be
  explained by the emerging-flux model, where newly emerging small flux
  tubes reconnect with pre-existing large coronal loops.

---------------------------------------------------------
Title: Coimbra Solar Physics Meeting: Ground-based Solar Observations
    in the Space Instrumentation Era
Authors: Dorotovic, I.; Fischer, C. E.; Temmer, M.
2016ASPC..504.....D    Altcode:
  No abstract at ADS

---------------------------------------------------------
Title: Projection effects in coronal dimmings and associated EUV
    wave event
Authors: Dissauer, Karin; Temmer, Manuela; Veronig, Astrid;
   Vanninathan, Kamalam; Magdalenic, Jasmina
2016EGUGA..18.6857D    Altcode:
  We investigate the high-speed (v &gt; 1000 km s-1) extreme-ultraviolet
  (EUV) wave associated with an X1.2 flare and coronal mass ejection (CME)
  from NOAA active region 11283. This EUV wave features peculiar on-disk
  signatures, in particular we observe an intermittent "disappearance"
  of the front for 120 s in SDO/AIA 171, 193, 211 Å data, whereas
  the 335 Å filter, sensitive to hotter plasmas (T∼ 2.5 MK), shows
  a continuous evolution of the wave front. We exploit the multi-point
  quadrature position of SDO and STEREO-A, to make a thorough analysis of
  the EUV wave evolution, with respect to its kinematics and amplitude
  evolution. We identify on-disk coronal dimming regions in SDO/AIA,
  reminiscent of core dimmings, that have no corresponding on-disk dimming
  signatures in STEREO-A/EUVI. Reconstructing the SDO line-of-sight (LOS)
  direction in STEREO-A clearly shows that the observed SDO on-disk
  dimming areas are not the footprints of the erupting fluxrope but
  result from decreased emission from the expanding CME body integrated
  along the LOS. In this context, we conclude that the intermittent
  disappearance of the EUV wave in the AIA 171, 193, 211 Å filters,
  which are channels sensitive to plasma with temperatures below ∼ 2
  MK is also caused by such LOS integration effects. These observations
  clearly demonstrate that single-view image data provide us with limited
  insight to correctly interpret coronal features.

---------------------------------------------------------
Title: Chromospheric evaporation flows and density changes deduced
    from Hinode/EIS during an M1.6 flare
Authors: Gömöry, P.; Veronig, A. M.; Su, Y.; Temmer, M.; Thalmann,
   J. K.
2016A&A...588A...6G    Altcode: 2016arXiv160202145G
  <BR /> Aims: We study the response of the solar atmosphere during a GOES
  M1.6 flare using spectroscopic and imaging observations. In particular,
  we examine the evolution of the mass flows and electron density together
  with the energy input derived from hard X-ray (HXR) in the context of
  chromospheric evaporation. <BR /> Methods: We analyzed high-cadence
  sit-and-stare observations acquired with the Hinode/EIS spectrometer
  in the Fe xiii 202.044 Å (log T = 6.2) and Fe xvi 262.980 Å (log T =
  6.4) spectral lines to derive temporal variations of the line intensity,
  Doppler shifts, and electron density during the flare. We combined these
  data with HXR measurements acquired with RHESSI to derive the energy
  input to the lower atmosphere by flare-accelerated electrons. <BR />
  Results: During the flare impulsive phase, we observe no significant
  flows in the cooler Fe xiii line but strong upflows, up to 80-150 km
  s<SUP>-1</SUP>, in the hotter Fe xvi line. The largest Doppler shifts
  observed in the Fe xvi line were co-temporal with the sharp intensity
  peak. The electron density obtained from a Fe xiii line pair ratio
  exhibited fast increase (within two minutes) from the pre-flare level
  of 5.01 × 10<SUP>9</SUP> cm<SUP>-3</SUP> to 3.16 × 10<SUP>10</SUP>
  cm<SUP>-3</SUP> during the flare peak. The nonthermal energy flux
  density deposited from the coronal acceleration site to the lower
  atmospheric layers during the flare peak was found to be 1.34 ×
  10<SUP>10</SUP> erg s<SUP>-1</SUP> cm<SUP>-2</SUP> for a low-energy
  cut-off that was estimated to be 16 keV. During the decline flare phase,
  we found a secondary intensity and density peak of lower amplitude
  that was preceded by upflows of ~15 km s<SUP>-1</SUP> that were
  detected in both lines. The flare was also accompanied by a filament
  eruption that was partly captured by the EIS observations. We derived
  Doppler velocities of 250-300 km s<SUP>-1</SUP> for the upflowing
  filament material. <BR /> Conclusions: The spectroscopic results
  for the flare peak are consistent with the scenario of explosive
  chromospheric evaporation, although a comparatively low value of the
  nonthermal energy flux density was determined for this phase of the
  flare. This outcome is discussed in the context of recent hydrodynamic
  simulations. It provides observational evidence that the response
  of the atmospheric plasma strongly depends on the properties of the
  electron beams responsible for the heating, in particular the steepness
  of the energy distribution. The secondary peak of line intensity and
  electron density detected during the decline phase is interpreted as a
  signature of flare loops being filled by expanding hot material that
  is due to chromospheric evaporation. <P />A movie is available at <A
  href="http://www.aanda.org/10.1051/0004-6361/201527403/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: Space Weather and confined CME events
Authors: Thalmann, Julia; Temmer, Manuela; Veronig, Astrid; Su, Yang
2016EGUGA..18.7517T    Altcode:
  The unusually large NOAA active region (AR) 2192, observed in October
  and November 2014, was outstanding in its productivity of major flares
  (GOES class M5 and larger). During the time when the AR faced Earth,
  major Space Weather events would have been expected. However, none of
  the X-flares was associated to a coronal mass ejection. Observational
  evidence for the confinement of the flare are large initial separation
  of the flare ribbons, together with an almost absent growth in ribbon
  separation. The low dynamic of the ribbons also suggests a reconnection
  site high up in the corona. From NLFF modeling we show that the
  arcade overlying the AR had a predominantly north-south oriented
  magnetic system, which served as a strong, also lateral, confinement
  for the flares at the core of the active region. From the magnetic
  field modeling we derived the decay of the constraining background,
  and it was found that the overlying field was only slowly decaying
  with height. We conclude that observational data of the solar surface,
  especially of flare ribbon dynamics as well as magnetic field models
  support Space Weather predictions.

---------------------------------------------------------
Title: ENLIL Global Heliospheric Modeling as a Context For Multipoint
    Observations
Authors: Mays, M. Leila; Odstrcil, Dusan; Luhmann, Janet; Bain, Hazel;
   Li, Yan; Schwadron, Nathan; Gorby, Matt; Thompson, Barbara; Jian,
   Lan; Möstl, Christian; Rouillard, Alexis; Davies, Jackie; Temmer,
   Manuela; Rastaetter, Lutz; Taktakishvili, Aleksandre; MacNeice, Peter;
   Kuznetsova, Maria
2016EGUGA..1811638M    Altcode:
  We present heliospheric simulation case studies using recent
  enhancements to WSA--ENLIL+Cone (version 2.8) at the Community
  Coordinated Modeling Center (CCMC). The global 3D MHD ENLIL model
  provides a time-dependent description of the background solar wind
  plasma and magnetic field using a sequence of WSA coronal model
  maps as input at the inner boundary of 21.5 Rs. A homogeneous,
  over-pressured hydrodynamic plasma cloud is launched through the
  inner boundary of the heliospheric computational domain and into
  the background solar wind. Multipoint observations help constrain
  simulations and this modeling system provides global context and
  arrival times of the solar wind streams and CMEs at Earth, planets,
  and spacecraft. Additionally, one can extract the magnetic topologies
  of observer-connected magnetic field lines and all plasma and shock
  properties along those field lines. ENLIL "likelihood/all-clear"
  forecasting maps provide expected intensity, timing/duration of events
  at locations throughout the heliosphere with "possible SEP affected
  areas" color-coded based on shock strength. ENLIL simulations are also
  useful to drive SEP models such as the Solar Energetic Particle Model
  (SEPMOD) (Luhmann et al. 2007, 2010) and Energetic Particle Radiation
  Environment Module (EPREM) (Schwadron et al., 2010). SEPMOD injects
  protons onto a sequence observer field lines at intensities dependent
  on the connected shock source strength which are then integrated at
  the observer to approximate the proton flux. EPREM couples with MHD
  models such as ENLIL and computes energetic particle distributions
  based on the focused transport equation along a Lagrangian grid of
  nodes that propagate out with the solar wind. Studies have shown
  that accurate descriptions of the heliosphere, and hence modeled CME
  arrival times and SEPs, are achieved by ENLIL only when the background
  solar wind is well-reproduced and CME parameters are accurate. It is
  essential to include all of the relevant CMEs and allow enough time
  for the events to propagate and interact. In this presentation we
  demonstrate several event case studies of ENLIL simulations compared
  with multipoint observations, exploring the background solar wind and
  CME pre-conditioning, and including comparisons between ENLIL synthetic
  j-maps with observed STEREO/HI j-maps using catalogues from the HELCATS
  FP7 project.

---------------------------------------------------------
Title: Forecasting the Arrival of Coronal Mass Ejections: The
    Drag-Based Model
Authors: Vršnak, B.; Temmer, M.; Zic, T.; Dumbović, M.; Čalogović,
   J.
2016ASPC..504..209V    Altcode:
  Arrival-time predictions based on the numerical "WSA-ENLIL+Cone model"
  and the analytical "Drag-based model" (DBM) are analyzed, employing
  a sample of 50 well observed CMEs. The best match between the two
  models is obtained if the background solar-wind speed of w = 400 km
  s<SUP>-1</SUP> is applied in DBM. It is also demonstrated that both
  models show similar prediction accuracy.

---------------------------------------------------------
Title: Impact of coronal mass ejections on the Earth's thermosphere
and geoeffectiveness observed by ACE and GRACE: Statistical results
Authors: Krauss, Sandro; Temmer, Manuela; Veronig, Astrid; Baur, Oliver
2016EGUGA..18.9350K    Altcode:
  For the period July 2003 to August 2010, the interplanetary coronal
  mass ejection (ICME) catalogue maintained by Richardson and Cane
  lists 106 Earth-directed events, which have been measured in situ by
  plasma and field instruments on board the ACE satellite. We present a
  statistical investigation of the Earth's thermospheric neutral density
  response by means of accelerometer measurements collected by the
  Gravity Recovery And Climate Experiment (GRACE) satellites, which are
  available for 104 ICMEs in the data set. We relate the thermospheric
  density increase to various geomagnetic indices (e.g. Dst, AE, Kp,
  a-indices, ...) and characteristic ICME parameters (impact speed,
  southward magnetic field strength Bz). We find high correlations
  between the ICME Bz and thermospheric density enhancements as well as
  with most of the geomagnetic indices. Separating the response for the
  shock-sheath region and the magnetic structure of the ICME, we find
  for instance that the Dst and SYM-H indices reveal a tighter relation
  to the Bz minimum in the magnetic structure of the ICME, whereas the
  polar cap indices show higher correlations with the Bz minimum in the
  shock-sheath region. These results are expected to further stimulate
  progress in space weather understanding and applications regarding
  satellite operations.

---------------------------------------------------------
Title: Injection of solar energetic particles into both loop legs
    of a magnetic cloud
Authors: Dresing, N.; Gómez-Herrero, R.; Heber, B.; Hidalgo, M. A.;
   Klassen, A.; Temmer, M.; Veronig, A.
2016A&A...586A..55D    Altcode: 2016arXiv160100491D
  Context. Each of the two Solar TErrestrial RElations Observatory
  (STEREO) spacecraft carries a Solar Electron and Proton Telescope
  (SEPT) which measures electrons and protons. Anisotropy observations
  are provided in four viewing directions: along the nominal magnetic
  field Parker spiral in the ecliptic towards the Sun (SUN) and
  away from the Sun (Anti-Sun/ASUN), and towards the north (NORTH)
  and south (SOUTH). The solar energetic particle (SEP) event on 7
  November 2013 was observed by both STEREO spacecraft, which were
  longitudinally separated by 68° at that time. While STEREO A observed
  the expected characteristics of an SEP event at a well-connected
  position, STEREO B detected a very anisotropic bi-directional
  distribution of near-relativistic electrons and was situated inside a
  magnetic-cloud-like structure during the early phase of the event. <BR
  /> Aims: We examine the source of the bi-directional SEP distribution
  at STEREO B. On the one hand this distribution could be caused by a
  double injection into both loop legs of the magnetic cloud (MC). On the
  other hand, a mirroring scenario where the incident beam is reflected in
  the opposite loop leg could be the reason. Furthermore, the energetic
  electron observations are used to probe the magnetic structure inside
  the magnetic cloud. <BR /> Methods: We investigate in situ plasma
  and magnetic field observations and show that STEREO B was embedded
  in an MC-like structure ejected three days earlier on 4 November from
  the same active region. We apply a Graduated Cylindrical Shell (GCS)
  model to the coronagraph observations from three viewpoints as well
  as the Global Magnetic Cloud (GMC) model to the in situ measurements
  at STEREO B to determine the orientation and topology of the MC
  close to the Sun and at 1 AU. We also estimate the path lengths of
  the electrons propagating through the MC to estimate the amount of
  magnetic field line winding inside the structure. <BR /> Results:
  The relative intensity and timing of the energetic electron increases
  in the different SEPT telescopes at STEREO B strongly suggest that the
  bi-directional electron distribution is formed by SEP injections in both
  loop legs of the MC separately instead of by mirroring farther away
  beyond the STEREO orbit. Observations by the Nançay Radioheliograph
  (NRH) of two distinct radio sources during the SEP injection further
  support the above scenario. The determined electron path lengths are
  around 50% longer than the estimated lengths of the loop legs of the
  MC itself (based on the GCS model) suggesting that the amount of field
  line winding is moderate.

---------------------------------------------------------
Title: 70 Years of Sunspot Observations at Kanzelhoehe Observatory
Authors: Pötzi, W.; Veronig, A.; Temmer, M.; Baumgartner, D. J.;
   Freislich, H.; Strutzmann, H.
2016CEAB...40..143P    Altcode:
  During World War II the German Airforce established a network of
  observatories, among them the Kanzelhöhe Observatory (KSO), which
  would provide information on solar activity in order to investigate
  the conditions of the Earth's ionosphere in terms of radio-wave
  propagation. Solar observations began already in 1943 with photographs
  of the photosphere and drawings of sunspots, plage regions and faculae,
  as well as patrol observations of the solar corona. Since 1944 relative
  sunspot numbers were derived, these relative numbers agree with the new
  International Sunspot Number tep[ISN,][]{SIDC,Clette2014} within ≈
  10%. However, revisiting the historical data, we also find periods with
  larger deviations. There were two main reasons for these deviations. On
  the one hand major instrumental changes took place and the instrument
  was relocated to another observation tower. On the other hand there
  were periods of frequent replacements of personnel. In the long term,
  the instrumental improvements led to better image quality, and a trend
  towards better seeing conditions since the year 2000 was found.

---------------------------------------------------------
Title: Formation of Coronal Large-Amplitude Waves and the
    Chromospheric Response
Authors: Vršnak, B.; Žic, T.; Lulić, S.; Temmer, M.; Veronig, A. M.
2016SoPh..291...89V    Altcode: 2015SoPh..tmp..175V
  An in-depth analysis of numerical simulations is performed to obtain
  a deeper insight into the nature of various phenomena occurring in the
  solar atmosphere as a consequence of the eruption of unstable coronal
  structures. Although the simulations take into account only the most
  basic characteristics of a flux-rope eruption, the simulation analysis
  reveals important information on various eruption-related effects. It
  quantifies the relation between the eruption dynamics and the evolution
  of the large-amplitude coronal magnetohydrodynamic wave and the
  associated chromospheric downward-propagating perturbation. We show that
  the downward propagation of the chromospheric Moreton-wave disturbance
  can be approximated by a constant-amplitude switch-on shock that moves
  through a medium of rapidly decreasing Alfvén velocity. The presented
  analysis reveals the nature of secondary effects that are observed
  as coronal upflows, secondary shocks, various forms of wave-trains,
  delayed large-amplitude slow disturbances, transient coronal depletions,
  etc. We also show that the eruption can cause an observable Moreton
  wave and a secondary coronal front only if it is powerful enough and
  is preferably characterized by significant lateral expansion. In weaker
  eruptions, only the coronal and transition-region signatures of primary
  waves are expected to be observed. In powerful events, the primary
  wave moves at an Alfvén Mach number significantly larger than 1 and
  steepens into a shock that is due to the nonlinear evolution of the
  wavefront. After the eruption-driven phase, the perturbation evolves
  as a freely propagating simple wave, characterized by a significant
  deceleration, amplitude decrease, and wave-profile broadening. In weak
  events the coronal wave does not develop into a shock and propagates
  at a speed close to the ambient magnetosonic speed.

---------------------------------------------------------
Title: ALMA Observations of the Sun in Cycle 4 and Beyond
Authors: Wedemeyer, S.; Fleck, B.; Battaglia, M.; Labrosse, N.;
   Fleishman, G.; Hudson, H.; Antolin, P.; Alissandrakis, C.; Ayres, T.;
   Ballester, J.; Bastian, T.; Black, J.; Benz, A.; Brajsa, R.; Carlsson,
   M.; Costa, J.; DePontieu, B.; Doyle, G.; Gimenez de Castro, G.;
   Gunár, S.; Harper, G.; Jafarzadeh, S.; Loukitcheva, M.; Nakariakov,
   V.; Oliver, R.; Schmieder, B.; Selhorst, C.; Shimojo, M.; Simões,
   P.; Soler, R.; Temmer, M.; Tiwari, S.; Van Doorsselaere, T.; Veronig,
   A.; White, S.; Yagoubov, P.; Zaqarashvili, T.
2016arXiv160100587W    Altcode:
  This document was created by the Solar Simulations for the Atacama
  Large Millimeter Observatory Network (SSALMON) in preparation of
  the first regular observations of the Sun with the Atacama Large
  Millimeter/submillimeter Array (ALMA), which are anticipated to start
  in ALMA Cycle 4 in October 2016. The science cases presented here
  demonstrate that a large number of scientifically highly interesting
  observations could be made already with the still limited solar
  observing modes foreseen for Cycle 4 and that ALMA has the potential
  to make important contributions to answering long-standing scientific
  questions in solar physics. With the proposal deadline for ALMA Cycle
  4 in April 2016 and the Commissioning and Science Verification campaign
  in December 2015 in sight, several of the SSALMON Expert Teams composed
  strategic documents in which they outlined potential solar observations
  that could be feasible given the anticipated technical capabilities
  in Cycle 4. These documents have been combined and supplemented
  with an analysis, resulting in recommendations for solar observing
  with ALMA in Cycle 4. In addition, the detailed science cases also
  demonstrate the scientific priorities of the solar physics community
  and which capabilities are wanted for the next observing cycles. The
  work on this White Paper effort was coordinated in close cooperation
  with the two international solar ALMA development studies led by
  T. Bastian (NRAO, USA) and R. Brajsa, (ESO). This document will be
  further updated until the beginning of Cycle 4 in October 2016. In
  particular, we plan to adjust the technical capabilities of the solar
  observing modes once finally decided and to further demonstrate the
  feasibility and scientific potential of the included science cases by
  means of numerical simulations of the solar atmosphere and corresponding
  simulated ALMA observations.

---------------------------------------------------------
Title: The exceptional aspects of the confined X-class flares of
    solar active region 2192
Authors: Thalmann, Julia K.; Su, Yang; Temmer, Manuela; Veronig,
   Astrid M.
2016IAUS..320...60T    Altcode: 2016arXiv160503712T
  During late October 2014, active region NOAA 2192 caused an unusual high
  level of solar activity, within an otherwise weak solar cycle. While
  crossing the solar disk, during a period of 11 days, it was the source
  of 114 flares of GOES class C1.0 and larger, including 29 M- and 6
  X-flares. Surprisingly, none of the major flares (GOES class M5.0
  and larger) was accompanied by a coronal mass ejection, contrary to
  statistical tendencies found in the past. From modeling the coronal
  magnetic field of NOAA 2192 and its surrounding, we suspect that the
  cause of the confined character of the flares is the strong surrounding
  and overlying large-scale magnetic field. Furthermore, we find evidence
  for multiple magnetic reconnection processes within a single flare,
  during which electrons were accelerated to unusual high energies.

---------------------------------------------------------
Title: STEREO Observations of an SEP Event Injected Into Both Loop
    Legs of a Magnetic Cloud
Authors: Dresing, N.; Gomez-Herrero, R.; Heber, B.; Hidalgo, M. A. U.;
   Klassen, A.; Temmer, M.; Veronig, A.
2015AGUFMSH42A..06D    Altcode:
  On 7 Nov 2013 STEREO B was embedded in a magnetic-cloud (MC)
  like structure when an SEP event occurred reaching both STEREO
  spacecraft. The bi-drectional near relativistic electron distribution
  observed by STEREO B reveals such timing and relative intensity
  characteristics suggesting that the SEPs were injected separately into
  both loop legs of the MC. Observations by the Nancay Radioheliograph
  (NRH) of two distinct radio sources at the same time further support
  the above scenario. In order to derive the 3D morphology and average
  speed of the CME close to the Sun, we use the graduated cylindrical
  shell model (GCS) which is applied to the white-light coronagraph
  observations by the STEREO spacecraft and SOHO. Furthermore, a global
  magnetic topology model for magnetic clouds is applied to the in-situ
  measurements of the magnetic field. Both models suggest that the MC is
  strongly inclined with respect to the ecliptic yielding a north/south
  orientation. The energetic electron observations are used to probe the
  structure of the magnetic cloud: We determine the electron path lengths
  along both loop legs of the structure to infer the amount of field
  line twist inside the MC. The resulting path lengths are around 50%
  longer than the estimated lengths of the loop legs of the MC itself
  suggesting that the amount of field line winding is moderate.

---------------------------------------------------------
Title: Low Solar Wind Density Causing the Fast Coronal Mass Ejection
    from 23 July 2012
Authors: Nitta, N.; Temmer, M.
2015AGUFMSH53A2458N    Altcode:
  The fast coronal mass ejection (CME) from July 23, 2012 raised special
  attention due to its short propagation time of less than 21hrs from
  Sun to 1 AU. In-situ data from STEREO-A revealed the arrival of a
  fast forward shock having a velocity of more than 2200 km/s followed
  by a magnetic structure with a speed of almost 1900 km/s. We study the
  evolution of the CME in interplanetary (IP) space using the drag based
  model to reproduce the short propagation time and high impact speed
  as derived from in-situ data. We find that the ambient density must
  have been exceptionally low due to which the drag force is reduced
  such that the CME experienced almost no deceleration. The density is
  found to be rather low due to the weak solar activity and was lowered
  even more by a previous CME event.

---------------------------------------------------------
Title: Propagation of the 7 January 2014 CME and Resulting Geomagnetic
    Non-event
Authors: Mays, M. L.; Thompson, B. J.; Jian, L. K.; Colaninno, R. C.;
   Odstrcil, D.; Möstl, C.; Temmer, M.; Savani, N. P.; Collinson, G.;
   Taktakishvili, A.; MacNeice, P. J.; Zheng, Y.
2015ApJ...812..145M    Altcode: 2015arXiv150906477M
  On 2014 January 7 an X1.2 flare and coronal mass ejection (CME) with a
  radial speed ≈2500 km s<SUP>-1</SUP> was observed from near an active
  region close to disk center. This led many forecasters to estimate a
  rapid arrival at Earth (≈36 hr) and predict a strong geomagnetic
  storm. However, only a glancing CME arrival was observed at Earth
  with a transit time of ≈49 hr and a K <SUB>P</SUB> geomagnetic
  index of only 3-. We study the interplanetary propagation of this
  CME using the ensemble Wang-Sheeley-Arge (WSA)-ENLIL+Cone model,
  that allows a sampling of CME parameter uncertainties. We explore a
  series of simulations to isolate the effects of the background solar
  wind solution, CME shape, tilt, location, size, and speed, and the
  results are compared with observed in situ arrivals at Venus, Earth,
  and Mars. Our results show that a tilted ellipsoid CME shape improves
  the initial real-time prediction to better reflect the observed in situ
  signatures and the geomagnetic storm strength. CME parameters from the
  Graduated Cylindrical Shell model used as input to WSA-ENLIL+Cone, along
  with a tilted ellipsoid cloud shape, improve the arrival-time error
  by 14.5, 18.7, 23.4 hr for Venus, Earth, and Mars respectively. These
  results highlight that CME orientation and directionality with respect
  to observatories play an important role in understanding the propagation
  of this CME, and for forecasting other glancing CME arrivals. This study
  also demonstrates the importance of three-dimensional CME fitting made
  possible by multiple viewpoint imaging.

---------------------------------------------------------
Title: Thermospheric and geomagnetic responses to interplanetary
coronal mass ejections observed by ACE and GRACE: Statistical results
Authors: Krauss, S.; Temmer, M.; Veronig, A.; Baur, O.; Lammer, H.
2015JGRA..120.8848K    Altcode: 2015arXiv151003549K
  For the period July 2003 to August 2010, the interplanetary coronal mass
  ejection (ICME) catalogue maintained by Richardson and Cane lists 106
  Earth-directed events, which have been measured in situ by plasma and
  field instruments on board the ACE satellite. We present a statistical
  investigation of the Earth's thermospheric neutral density response by
  means of accelerometer measurements collected by the Gravity Recovery
  And Climate Experiment (GRACE) satellites, which are available for
  104 ICMEs in the data set, and its relation to various geomagnetic
  indices and characteristic ICME parameters such as the impact speed
  (vmax), southward magnetic field strength (B<SUB>z</SUB>). The majority
  of ICMEs causes a distinct density enhancement in the thermosphere,
  with up to a factor of 8 compared to the preevent level. We find high
  correlations between ICME B<SUB>z</SUB> and thermospheric density
  enhancements (≈0.9), while the correlation with the ICME impact speed
  is somewhat smaller (≈0.7). The geomagnetic indices revealing the
  highest correlations are Dst and SYM-H(≈0.9); the lowest correlations
  are obtained for Kp and AE (≈0.7), which show a nonlinear relation
  with the thermospheric density enhancements. Separating the response for
  the shock-sheath region and the magnetic structure of the ICME, we find
  that the Dst and SYM-H reveal a tighter relation to the B<SUB>z</SUB>
  minimum in the magnetic structure of the ICME, whereas the polar cap
  indices show higher correlations with the B<SUB>z</SUB> minimum in
  the shock-sheath region. Since the strength of the B<SUB>z</SUB>
  component—either in the sheath or in the magnetic structure of
  the ICME—is highly correlated (≈0.9) with the neutral density
  enhancement, we discuss the possibility of satellite orbital decay
  estimates based on magnetic field measurements at L1, i.e., before
  the ICME hits the Earth magnetosphere. These results are expected
  to further stimulate progress in space weather understanding and
  applications regarding satellite operations.

---------------------------------------------------------
Title: The exceptional aspects of the confined X-Flares of Solar
    Active Region 2192
Authors: Thalmann, Julia K.; Su, Yang; Temmer, Manuela; Veronig, Astrid
2015IAUGA..2215645T    Altcode:
  Active region NOAA 2192 showed an outstanding productivity
  of major (GOES class M5 and larger) two-ribbon flares lacking
  eruptive events. None of the X-flares was associated to a coronal
  mass ejection. The major confined flares on 2014 October 22 and 24
  originated from the active-region core and were prohibited to develop
  an associated mass ejection due to the confinement of the overlying
  strong magnetic field. In contrast, the single eruptive M-flare on
  October 24 originated from the outer parts of the active region, in the
  neighborhood of open large-scale fields, which allowed for the observed
  mass ejection. Analysis of the spacial and temporal characteristics
  of the major confined flares revealed exceptional aspects, including a
  large initial separation of the confined flares' ribbons and an almost
  absent growth in ribbon separation, suggesting a reconnection site
  high up in the corona. Furthermore, detailed analysis of a confined
  X-flare on October 22 provides evidence that magnetic field structures
  were repeatedly involved in magnetic reconnection, that a large number
  of electrons was accelerated to non-thermal energies but that only a
  small fraction out of these accelerated electrons was accelerated to
  high energies. We conclude the latter due to the unusual steepness
  of the associated power law spectrum. Finally, we demonstrate that
  a considerable portion of the magnetic energy released during the
  X-flare was consumed by the non-thermal flare energy.

---------------------------------------------------------
Title: Improvements on coronal hole detection in SDO/AIA images
    using supervised classification
Authors: Reiss, Martin A.; Hofmeister, Stefan J.; De Visscher, Ruben;
   Temmer, Manuela; Veronig, Astrid M.; Delouille, Véronique; Mampaey,
   Benjamin; Ahammer, Helmut
2015JSWSC...5A..23R    Altcode: 2015arXiv150606623R
  We demonstrate the use of machine learning algorithms in combination
  with segmentation techniques in order to distinguish coronal holes
  and filaments in SDO/AIA EUV images of the Sun. Based on two coronal
  hole detection techniques (intensity-based thresholding, SPoCA), we
  prepared datasets of manually labeled coronal hole and filament channel
  regions present on the Sun during the time range 2011-2013. By mapping
  the extracted regions from EUV observations onto HMI line-of-sight
  magnetograms we also include their magnetic characteristics. We computed
  shape measures from the segmented binary maps as well as first order
  and second order texture statistics from the segmented regions in
  the EUV images and magnetograms. These attributes were used for
  data mining investigations to identify the most performant rule to
  differentiate between coronal holes and filament channels. We applied
  several classifiers, namely Support Vector Machine (SVM), Linear Support
  Vector Machine, Decision Tree, and Random Forest, and found that all
  classification rules achieve good results in general, with linear SVM
  providing the best performances (with a true skill statistic of ≈
  0.90). Additional information from magnetic field data systematically
  improves the performance across all four classifiers for the SPoCA
  detection. Since the calculation is inexpensive in computing time,
  this approach is well suited for applications on real-time data. This
  study demonstrates how a machine learning approach may help improve
  upon an unsupervised feature extraction method.

---------------------------------------------------------
Title: Heliospheric Propagation of Coronal Mass Ejections: Drag-based
    Model Fitting
Authors: Žic, T.; Vršnak, B.; Temmer, M.
2015ApJS..218...32Z    Altcode: 2015arXiv150608582Z
  The so-called drag-based model (DBM) simulates analytically the
  propagation of coronal mass ejections (CMEs) in interplanetary space
  and allows the prediction of their arrival times and impact speeds at
  any point in the heliosphere (“target”). The DBM is based on the
  assumption that beyond a distance of about 20 solar radii from the
  Sun, the dominant force acting on CMEs is the “aerodynamic” drag
  force. In the standard form of DBM, the user provisionally chooses
  values for the model input parameters, by which the kinematics of the
  CME over the entire Sun-“target” distance range is defined. The
  choice of model input parameters is usually based on several previously
  undertaken statistical studies. In other words, the model is used
  by ad hoc implementation of statistics-based values of the input
  parameters, which are not necessarily appropriate for the CME under
  study. Furthermore, such a procedure lacks quantitative information
  on how well the simulation reproduces the coronagraphically observed
  kinematics of the CME, and thus does not provide an estimate of the
  reliability of the arrival prediction. In this paper we advance the DBM
  by adopting it in a form that employs the CME observations over a given
  distance range to evaluate the most suitable model input parameters
  for a given CME by means of least-squares fitting. Furthermore, the
  new version of the model automatically responds to any significant
  change of the conditions in the ambient medium (solar wind speed,
  density, CME-CME interactions, etc.) by changing the model input
  parameters according to changes in the CME kinematics. The advanced
  DBM is shaped in a form that can be readily employed in an operational
  system for real-time space-weather forecasting by promptly adjusting
  to a successively expanding observational data set, thus providing a
  successively improving prediction of the CME arrival.

---------------------------------------------------------
Title: Strong coronal channelling and interplanetary evolution of
    a solar storm up to Earth and Mars
Authors: Möstl, Christian; Rollett, Tanja; Frahm, Rudy A.; Liu,
   Ying D.; Long, David M.; Colaninno, Robin C.; Reiss, Martin A.;
   Temmer, Manuela; Farrugia, Charles J.; Posner, Arik; Dumbović,
   Mateja; Janvier, Miho; Démoulin, Pascal; Boakes, Peter; Devos, Andy;
   Kraaikamp, Emil; Mays, Mona L.; Vršnak, Bojan
2015NatCo...6.7135M    Altcode: 2015arXiv150602842M; 2015NatCo...6E7135M
  The severe geomagnetic effects of solar storms or coronal mass
  ejections (CMEs) are to a large degree determined by their propagation
  direction with respect to Earth. There is a lack of understanding of
  the processes that determine their non-radial propagation. Here we
  present a synthesis of data from seven different space missions of a
  fast CME, which originated in an active region near the disk centre
  and, hence, a significant geomagnetic impact was forecasted. However,
  the CME is demonstrated to be channelled during eruption into a
  direction +37+/-10° (longitude) away from its source region, leading
  only to minimal geomagnetic effects. In situ observations near Earth
  and Mars confirm the channelled CME motion, and are consistent with
  an ellipse shape of the CME-driven shock provided by the new Ellipse
  Evolution model, presented here. The results enhance our understanding
  of CME propagation and shape, which can help to improve space weather
  forecasts.

---------------------------------------------------------
Title: Real-Time Solar Wind Prediction Based on SDO/AIA Coronal
    Hole Data
Authors: Rotter, T.; Veronig, A. M.; Temmer, M.; Vršnak, B.
2015SoPh..290.1355R    Altcode: 2015arXiv150106697R; 2015SoPh..tmp...37R
  We present an empirical model based on the visible area covered by
  coronal holes close to the central meridian with the aim to predict
  the solar wind speed at 1 AU with a lead time of up to four days in
  advance with a time resolution of one hour. Linear prediction functions
  are used to relate coronal hole areas to solar wind speed. The function
  parameters are automatically adapted by using the information from the
  previous three Carrington Rotations. Thus the algorithm automatically
  reacts to the changes of the solar wind speed during different phases
  of the solar cycle. The adaptive algorithm was applied to and tested
  on SDO/AIA-193 Å observations and ACE measurements during the years
  2011 - 2013, covering 41 Carrington Rotations. The solar wind needs
  on average 4.02±0.5 days to reach Earth. The algorithm produces good
  predictions for the 156 solar wind high-speed streams peak amplitudes
  with correlation coefficients of cc≈0.60. For 80 % of the peaks,
  the predicted arrival matches the ACE in situ measurements within a
  time window of 0.5 days. The same algorithm, using linear predictions,
  was also applied to predict the magnetic field strength in wind streams
  originating from coronal hole areas, but it did not give reliable
  predictions (cc≈0.15).

---------------------------------------------------------
Title: Strong coronal deflection of a CME and its interplanetary
    evolution to Earth and Mars
Authors: Möstl, Christian; Rollett, Tanja; Frahm, Rudy A.; Liu, Ying
   D.; Long, David M.; Colaninno, Robin C.; Reiss, Martin A.; Temmer,
   Manuela; Farrugia, Charles J.; Posner, Arik; Dumbovic, Mateja; Janvier,
   Miho; Demoulin, Pascal; Boakes, Peter; Devos, Andy; Kraaikamp, Emil;
   Mays, Mona L.; Vrsnak, Bojan
2015EGUGA..17.1366M    Altcode:
  We discuss multipoint imaging and in situ observations of the coronal
  mass ejection (CME) on January 7 2014 which resulted in a major false
  alarm. While the source region was almost at disk center facing Earth,
  the eruption was strongly deflected in the corona, and in conjunction
  with its particular orientation this CME missed Earth almost entirely,
  leading to no significant geomagnetic effects. We demonstrate this
  by a synthesis of data from 7 different heliospheric and planetary
  space missions (STEREO-A/B, SOHO, SDO, Wind, Mars Express, Mars
  Science Laboratory). The CMEs ecliptic part was deflected by 37
  ± 10° in heliospheric longitude, a value larger than previously
  thought. Multipoint in situ observations at Earth and Mars confirm
  the deflection, and are consistent with an elliptical interplanetary
  shock shape of aspect ratio 1.4 ± 0.4. We also discuss our new method,
  the Ellipse Evolution (ElEvo) model, which allows us to optimize the
  global shape of the CME shock with multipoint in situ observations of
  the interplanetary CME arrival. ElEvo, which is an extension to the
  Drag-Based-Model by Vrsnak et al., may also be used for real time space
  weather forecasting. The presented results enhance our understanding
  of CME deflection and shape, which are fundamental ingredients for
  improving space weather forecasts.

---------------------------------------------------------
Title: The Confined X-class Flares of Solar Active Region 2192
Authors: Thalmann, J. K.; Su, Y.; Temmer, M.; Veronig, A. M.
2015ApJ...801L..23T    Altcode: 2015arXiv150205157T
  The unusually large active region (AR) NOAA 2192, observed in 2014
  October, was outstanding in its productivity of major two-ribbon flares
  without coronal mass ejections. On a large scale, a predominantly
  north-south oriented magnetic system of arcade fields served as a strong
  top and lateral confinement for a series of large two-ribbon flares
  originating from the core of the AR. The large initial separation of
  the flare ribbons, together with an almost absent growth in ribbon
  separation, suggests a confined reconnection site high up in the
  corona. Based on a detailed analysis of the confined X1.6 flare on
  October 22, we show how exceptional the flaring of this AR was. We
  provide evidence for repeated energy release, indicating that the
  same magnetic field structures were repeatedly involved in magnetic
  reconnection. We find that a large number of electrons was accelerated
  to non-thermal energies, revealing a steep power-law spectrum, but
  that only a small fraction was accelerated to high energies. The total
  non-thermal energy in electrons derived (on the order of 10<SUP>25</SUP>
  J) is considerably higher than that in eruptive flares of class X1,
  and corresponds to about 10% of the excess magnetic energy present in
  the active-region corona.

---------------------------------------------------------
Title: Interplanetary Propagation Behavior of the Fast Coronal Mass
    Ejection on 23 July 2012
Authors: Temmer, M.; Nitta, N. V.
2015SoPh..290..919T    Altcode: 2015SoPh..tmp....2T; 2014arXiv1411.6559T
  The fast coronal mass ejection (CME) on 23 July 2012 caused attention
  because of its extremely short transit time from the Sun to 1 AU,
  which was shorter than 21 h. In situ data from STEREO-A revealed the
  arrival of a fast forward shock with a speed of more than 2200 km
  s<SUP>−1</SUP> followed by a magnetic structure moving with almost
  1900 km s<SUP>−1</SUP>. We investigate the propagation behavior of the
  CME shock and magnetic structure with the aim to reproduce the short
  transit time and high impact speed as derived from in situ data. We
  carefully measured the 3D kinematics of the CME using the graduated
  cylindrical shell model and obtained a maximum speed of 2580±280 km
  s<SUP>−1</SUP> for the CME shock and 2270±420 km s<SUP>−1</SUP>
  for its magnetic structure. Based on the 3D kinematics, the drag-based
  model (DBM) reproduces the observational data reasonably well. To
  successfully simulate the CME shock, the ambient flow speed needs
  to have an average value close to the slow solar wind speed (450
  km s<SUP>−1</SUP>), and the initial shock speed at a distance of
  30 R<SUB>⊙</SUB> should not exceed ≈ 2300 km s<SUP>−1</SUP>,
  otherwise it would arrive much too early at STEREO-A. The model results
  indicate that an extremely small aerodynamic drag force is exerted
  on the shock, smaller by one order of magnitude than average. As
  a consequence, the CME hardly decelerates in interplanetary space
  and maintains its high initial speed. The low aerodynamic drag can
  only be reproduced when the density of the ambient solar wind flow,
  in which the fast CME propagates, is decreased to ρ<SUB>sw</SUB>=1 -
  2 cm<SUP>−3</SUP> at the distance of 1 AU. This result is consistent
  with the preconditioning of interplanetary space by a previous CME.

---------------------------------------------------------
Title: Real-time Flare Detection in Ground-Based Hα Imaging at
    Kanzelhöhe Observatory
Authors: Pötzi, W.; Veronig, A. M.; Riegler, G.; Amerstorfer, U.;
   Pock, T.; Temmer, M.; Polanec, W.; Baumgartner, D. J.
2015SoPh..290..951P    Altcode: 2014arXiv1411.3896P; 2014SoPh..tmp..193P
  Kanzelhöhe Observatory (KSO) regularly performs high-cadence full-disk
  imaging of the solar chromosphere in the Hα and Ca II K spectral
  lines as well as in the solar photosphere in white light. In the frame
  of ESA's (European Space Agency) Space Situational Awareness (SSA)
  program, a new system for real-time Hα data provision and automatic
  flare detection was developed at KSO. The data and events detected
  are published in near real-time at ESA's SSA Space Weather portal
  (http://swe.ssa.esa.int/web/guest/kso-federated). In this article,
  we describe the Hα instrument, the image-recognition algorithms we
  developed, and the implementation into the KSO Hα observing system. We
  also present the evaluation results of the real-time data provision
  and flare detection for a period of five months. The Hα data provision
  worked in 99.96 % of the images, with a mean time lag of four seconds
  between image recording and online provision. Within the given criteria
  for the automatic image-recognition system (at least three Hα images
  are needed for a positive detection), all flares with an area ≥ 50
  micro-hemispheres that were located within 60° of the solar center
  and occurred during the KSO observing times were detected, a number of
  87 events in total. The automatically determined flare importance and
  brightness classes were correct in ∼ 85 %. The mean flare positions in
  heliographic longitude and latitude were correct to within ∼ 1°. The
  median of the absolute differences for the flare start and peak times
  from the automatic detections in comparison with the official NOAA
  (and KSO) visual flare reports were 3 min (1 min).

---------------------------------------------------------
Title: Initiation and Evolution of Global Coronal Waves
Authors: Vršnak, B.; Muhr, N.; Žic, T.; Lulić, S.; Kienreich,
   I. W.; Temmer, M.; Veronig, A. M.
2015CEAB...39...65V    Altcode:
  Some essential outcomes of a detailed analysis of the formation and
  evolution of the coronal EUV wave of 15 February 2011 are presented,
  focused on the relationship between the source region expansion, wave
  kinematics, and the evolution of the wave amplitude. The observations
  are explained in terms of the results of the numerical MHD simulations,
  providing new insights into the physical background of coronal waves,
  especially considering the nature of the relationship of the wave
  amplitude and propagation velocity in different phases of the wave
  evolution.

---------------------------------------------------------
Title: The real-time flare detection system at Kanzelhöhe Observatory
Authors: Pötzi, W.; Veronig, A.; Riegler, G.; Amerstorfer, U.; Pock,
   TH.; Temmer, M.; Polanec, W.; Baumgartner, D. J.
2015CEAB...39..125P    Altcode:
  Kanzelhöhe Observatory performs regular high-cadence full-disk
  observations of the solar chromosphere in the Hα and Ca II K spectral
  lines as well as the solar photosphere in white-light. In the frame
  of ESA's Space Situational Awareness (SSA) activities, a system for
  near real-time H-alpha image provision through the SSA Space Weather
  (SWE) portal (swe.ssa.esa.int) and for automatic alerting of flares
  and erupting filaments was developed. Image segmentation algorithms,
  for the automatic detection of solar filaments in real time H-alpha
  images have been developed and implemented at the Kanzelhöhe observing
  system. We present results of this system with respect to the automatic
  recognition and segmentation of flares on the Sun.

---------------------------------------------------------
Title: Forbush decreases associated to Stealth Coronal Mass Ejections
Authors: Heber, B.; Wallmann, C.; Galsdorf, D.; Herbst K.; Kühl,
   P.; Dumbovic, M.; Vršnak, B.; Veronig, A.; Temmer, M.; Möstl, C.;
   Dalla, S.
2015CEAB...39...75H    Altcode:
  Interplanetary coronal mass ejections (ICMEs) are structures in the
  solar wind that are the counterparts of coronal mass ejections (CMEs)
  at the Sun. It is commonly believed that enhanced magnetic fields
  in interplanetary shocks and solar ejecta as well as the increased
  turbulence in the solar wind sheath region are the cause of Forbush
  decreases (FDs) representing decreases of galactic cosmic ray (GCR)
  intensities. Recently, stealth CMEs i.e.~CMEs with no apparent solar
  surface association have become a subject in recent studies of solar
  activity. Whether all of such stealth CMEs can drive a FD is difficult
  to investigate on the basis of neutron monitor NM measurements because
  these measurements not only reflect the GCR intensity variation in
  interplanetary space but also the variation of the geomagnetic field as
  well as the conditions in the Earth atmosphere. Single detector counter
  from spacecraft instrumentation, here SOHO and Chandra EPHIN, exceed
  counting statistic of NMs allowing to determine intensity variation of
  less than 1 permil in interplanetary space on the basis of 30 minute
  count rate averages. Here we present the ongoing analysis of eleven
  stealth CMEs.

---------------------------------------------------------
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).

---------------------------------------------------------
Title: Statistical Analysis of Large-Scale EUV Waves Observed by
    STEREO/EUVI
Authors: Muhr, N.; Veronig, A. M.; Kienreich, I. W.; Vršnak, B.;
   Temmer, M.; Bein, B. M.
2014SoPh..289.4563M    Altcode: 2014arXiv1408.2513M; 2014SoPh..tmp..126M
  We statistically analyzed the kinematical evolution and wave pulse
  characteristics of 60 strong large-scale EUV wave events that
  occurred during January 2007 to February 2011 with the STEREO
  twin spacecraft. For the start velocity, the arithmetic mean
  is 312±115 km s<SUP>−1</SUP> (within a range of 100 - 630 km
  s<SUP>−1</SUP>). For the mean (linear) velocity, the arithmetic
  mean is 254±76 km s<SUP>−1</SUP> (within a range of 130 - 470
  km s<SUP>−1</SUP>). 52 % of all waves under study show a distinct
  deceleration during their propagation (a≤−50 m s<SUP>−2</SUP>),
  the other 48 % are consistent with a constant speed within the
  uncertainties (−50≤a≤50 m s<SUP>−2</SUP>). The start velocity
  and the acceleration are strongly anticorrelated with c≈−0.8,
  i.e. initially faster events undergo stronger deceleration than
  slower events. The (smooth) transition between constant propagation
  for slow events and deceleration in faster events occurs at an EUV wave
  start-velocity of v≈230 km s<SUP>−1</SUP>, which corresponds well to
  the fast-mode speed in the quiet corona. These findings provide strong
  evidence that the EUV waves under study are indeed large-amplitude
  fast-mode MHD waves. This interpretation is also supported by the
  correlations obtained between the peak velocity and the peak amplitude,
  impulsiveness, and build-up time of the disturbance. We obtained
  the following association rates of EUV wave events with other solar
  phenomena: 95 % are associated with a coronal mass ejection (CME),
  74 % to a solar flare, 15 % to interplanetary type II bursts, and 22
  % to coronal type II bursts. These findings are consistent with the
  interpretation that the associated CMEs are the driving agents of the
  EUV waves.

---------------------------------------------------------
Title: Heliospheric Propagation of Coronal Mass Ejections: Comparison
    of Numerical WSA-ENLIL+Cone Model and Analytical Drag-based Model
Authors: Vršnak, B.; Temmer, M.; Žic, T.; Taktakishvili, A.;
   Dumbović, M.; Möstl, C.; Veronig, A. M.; Mays, M. L.; Odstrčil, D.
2014ApJS..213...21V    Altcode:
  Real-time forecasting of the arrival of coronal mass ejections (CMEs) at
  Earth, based on remote solar observations, is one of the central issues
  of space-weather research. In this paper, we compare arrival-time
  predictions calculated applying the numerical "WSA-ENLIL+Cone
  model" and the analytical "drag-based model" (DBM). Both models use
  coronagraphic observations of CMEs as input data, thus providing an
  early space-weather forecast two to four days before the arrival of
  the disturbance at the Earth, depending on the CME speed. It is shown
  that both methods give very similar results if the drag parameter Γ =
  0.1 is used in DBM in combination with a background solar-wind speed
  of w = 400 km s<SUP>-1</SUP>. For this combination, the mean value
  of the difference between arrival times calculated by ENLIL and DBM
  is \overline{Δ }=0.09+/- 9.0 hr with an average of the absolute-value
  differences of \overline{\vert Δ \vert }=7.1 hr. Comparing the observed
  arrivals (O) with the calculated ones (C) for ENLIL gives O - C = -0.3
  ± 16.9 hr and, analogously, O - C = +1.1 ± 19.1 hr for DBM. Applying
  Γ = 0.2 with w = 450 km s<SUP>-1</SUP> in DBM, one finds O - C =
  -1.7 ± 18.3 hr, with an average of the absolute-value differences
  of 14.8 hr, which is similar to that for ENLIL, 14.1 hr. Finally,
  we demonstrate that the prediction accuracy significantly degrades
  with increasing solar activity.

---------------------------------------------------------
Title: Combined Multipoint Remote and in situ Observations of the
    Asymmetric Evolution of a Fast Solar Coronal Mass Ejection
Authors: Rollett, T.; Möstl, C.; Temmer, M.; Frahm, R. A.; Davies,
   J. A.; Veronig, A. M.; Vršnak, B.; Amerstorfer, U. V.; Farrugia,
   C. J.; Žic, T.; Zhang, T. L.
2014ApJ...790L...6R    Altcode: 2014arXiv1407.4687R
  We present an analysis of the fast coronal mass ejection (CME) of 2012
  March 7, which was imaged by both STEREO spacecraft and observed in
  situ by MESSENGER, Venus Express, Wind, and Mars Express. Based on
  detected arrivals at four different positions in interplanetary space,
  it was possible to strongly constrain the kinematics and the shape of
  the ejection. Using the white-light heliospheric imagery from STEREO-A
  and B, we derived two different kinematical profiles for the CME
  by applying the novel constrained self-similar expansion method. In
  addition, we used a drag-based model to investigate the influence of
  the ambient solar wind on the CME's propagation. We found that two
  preceding CMEs heading in different directions disturbed the overall
  shape of the CME and influenced its propagation behavior. While the
  Venus-directed segment underwent a gradual deceleration (from ~2700 km
  s<SUP>-1</SUP> at 15 R <SUB>⊙</SUB> to ~1500 km s<SUP>-1</SUP> at 154
  R <SUB>⊙</SUB>), the Earth-directed part showed an abrupt retardation
  below 35 R <SUB>⊙</SUB> (from ~1700 to ~900 km s<SUP>-1</SUP>). After
  that, it was propagating with a quasi-constant speed in the wake of
  a preceding event. Our results highlight the importance of studies
  concerning the unequal evolution of CMEs. Forecasting can only be
  improved if conditions in the solar wind are properly taken into
  account and if attention is also paid to large events preceding the
  one being studied.

---------------------------------------------------------
Title: Solar Energetic Particles and Associated EIT Disturbances in
    Solar Cycle 23
Authors: Miteva, R.; Klein, K. -L.; Kienreich, I.; Temmer, M.; Veronig,
   A.; Malandraki, O. E.
2014SoPh..289.2601M    Altcode: 2014arXiv1402.1676M; 2014SoPh..tmp...37M
  We explore the link between solar energetic particles (SEPs) observed
  at 1 AU and large-scale disturbances propagating in the solar corona,
  named after the Extreme ultraviolet Imaging Telescope (EIT) as EIT
  waves, which trace the lateral expansion of a coronal mass ejection
  (CME). A comprehensive search for SOHO/EIT waves was carried out for
  179 SEP events during Solar Cycle 23 (1997 - 2006). 87 % of the SEP
  events were found to be accompanied by EIT waves. In order to test if
  the EIT waves play a role in the SEP acceleration, we compared their
  extrapolated arrival time at the footpoint of the Parker spiral with
  the particle onset in the 26 eastern SEP events that had no direct
  magnetic connection to the Earth. We find that the onset of proton
  events was generally consistent with this scenario. However, in a
  number of cases the first near-relativistic electrons were detected too
  early. Furthermore, the electrons had in general only weakly anisotropic
  pitch-angle distributions. This poses a problem for the idea that the
  SEPs were accelerated by the EIT wave or in any other spatially confined
  region in the low corona. The presence of weak electron anisotropies in
  SEP events from the eastern hemisphere suggests that transport processes
  in interplanetary space, including cross-field diffusion, play a role
  in giving the SEPs access to a broad range of helio-longitudes.

---------------------------------------------------------
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: Future mmVLBI Research with ALMA: A European vision
Authors: Tilanus, R. P. J.; Krichbaum, T. P.; Zensus, J. A.; Baudry,
   A.; Bremer, M.; Falcke, H.; Giovannini, G.; Laing, R.; van Langevelde,
   H. J.; Vlemmings, W.; Abraham, Z.; Afonso, J.; Agudo, I.; Alberdi,
   A.; Alcolea, J.; Altamirano, D.; Asadi, S.; Assaf, K.; Augusto, P.;
   Baczko, A-K.; Boeck, M.; Boller, T.; Bondi, M.; Boone, F.; Bourda,
   G.; Brajsa, R.; Brand, J.; Britzen, S.; Bujarrabal, V.; Cales, S.;
   Casadio, C.; Casasola, V.; Castangia, P.; Cernicharo, J.; Charlot,
   P.; Chemin, L.; Clenet, Y.; Colomer, F.; Combes, F.; Cordes, J.;
   Coriat, M.; Cross, N.; D'Ammando, F.; Dallacasa, D.; Desmurs, J-F.;
   Eatough, R.; Eckart, A.; Eisenacher, D.; Etoka, S.; Felix, M.; Fender,
   R.; Ferreira, M.; Freeland, E.; Frey, S.; Fromm, C.; Fuhrmann, L.;
   Gabanyi, K.; Galvan-Madrid, R.; Giroletti, M.; Goddi, C.; Gomez, J.;
   Gourgoulhon, E.; Gray, M.; di Gregorio, I.; Greimel, R.; Grosso, N.;
   Guirado, J.; Hada, K.; Hanslmeier, A.; Henkel, C.; Herpin, F.; Hess,
   P.; Hodgson, J.; Horns, D.; Humphreys, E.; Hutawarakorn Kramer, B.;
   Ilyushin, V.; Impellizzeri, V.; Ivanov, V.; Julião, M.; Kadler, M.;
   Kerins, E.; Klaassen, P.; van 't Klooster, K.; Kording, E.; Kozlov,
   M.; Kramer, M.; Kreikenbohm, A.; Kurtanidze, O.; Lazio, J.; Leite,
   A.; Leitzinger, M.; Lepine, J.; Levshakov, S.; Lico, R.; Lindqvist,
   M.; Liuzzo, E.; Lobanov, A.; Lucas, P.; Mannheim, K.; Marcaide, J.;
   Markoff, S.; Martí-Vidal, I.; Martins, C.; Masetti, N.; Massardi,
   M.; Menten, K.; Messias, H.; Migliari, S.; Mignano, A.; Miller-Jones,
   J.; Minniti, D.; Molaro, P.; Molina, S.; Monteiro, A.; Moscadelli,
   L.; Mueller, C.; Müller, A.; Muller, S.; Niederhofer, F.; Odert,
   P.; Olofsson, H.; Orienti, M.; Paladino, R.; Panessa, F.; Paragi,
   Z.; Paumard, T.; Pedrosa, P.; Pérez-Torres, M.; Perrin, G.; Perucho,
   M.; Porquet, D.; Prandoni, I.; Ransom, S.; Reimers, D.; Rejkuba, M.;
   Rezzolla, L.; Richards, A.; Ros, E.; Roy, A.; Rushton, A.; Savolainen,
   T.; Schulz, R.; Silva, M.; Sivakoff, G.; Soria-Ruiz, R.; Soria, R.;
   Spaans, M.; Spencer, R.; Stappers, B.; Surcis, G.; Tarchi, A.; Temmer,
   M.; Thompson, M.; Torrelles, J.; Truestedt, J.; Tudose, V.; Venturi,
   T.; Verbiest, J.; Vieira, J.; Vielzeuf, P.; Vincent, F.; Wex, N.;
   Wiik, K.; Wiklind, T.; Wilms, J.; Zackrisson, E.; Zechlin, H.
2014arXiv1406.4650T    Altcode:
  Very long baseline interferometry at millimetre/submillimetre
  wavelengths (mmVLBI) offers the highest achievable spatial
  resolution at any wavelength in astronomy. The anticipated inclusion
  of ALMA as a phased array into a global VLBI network will bring
  unprecedented sensitivity and a transformational leap in capabilities
  for mmVLBI. Building on years of pioneering efforts in the US and
  Europe the ongoing ALMA Phasing Project (APP), a US-led international
  collaboration with MPIfR-led European contributions, is expected to
  deliver a beamformer and VLBI capability to ALMA by the end of 2014
  (APP: Fish et al. 2013, arXiv:1309.3519). This report focuses on
  the future use of mmVLBI by the international users community from
  a European viewpoint. Firstly, it highlights the intense science
  interest in Europe in future mmVLBI observations as compiled from
  the responses to a general call to the European community for future
  research projects. A wide range of research is presented that includes,
  amongst others: - Imaging the event horizon of the black hole at the
  centre of the Galaxy - Testing the theory of General Relativity an/or
  searching for alternative theories - Studying the origin of AGN jets
  and jet formation - Cosmological evolution of galaxies and BHs, AGN
  feedback - Masers in the Milky Way (in stars and star-forming regions) -
  Extragalactic emission lines and astro-chemistry - Redshifted absorption
  lines in distant galaxies and study of the ISM and circumnuclear gas -
  Pulsars, neutron stars, X-ray binaries - Testing cosmology - Testing
  fundamental physical constants

---------------------------------------------------------
Title: Connecting Speeds, Directions and Arrival Times of 22 Coronal
    Mass Ejections from the Sun to 1 AU
Authors: Möstl, C.; Amla, K.; Hall, J. R.; Liewer, P. C.; De Jong,
   E. M.; Colaninno, R. C.; Veronig, A. M.; Rollett, T.; Temmer, M.;
   Peinhart, V.; Davies, J. A.; Lugaz, N.; Liu, Y. D.; Farrugia, C. J.;
   Luhmann, J. G.; Vršnak, B.; Harrison, R. A.; Galvin, A. B.
2014ApJ...787..119M    Altcode: 2014arXiv1404.3579M
  Forecasting the in situ properties of coronal mass ejections (CMEs)
  from remote images is expected to strongly enhance predictions of
  space weather and is of general interest for studying the interaction
  of CMEs with planetary environments. We study the feasibility of using
  a single heliospheric imager (HI) instrument, imaging the solar wind
  density from the Sun to 1 AU, for connecting remote images to in situ
  observations of CMEs. We compare the predictions of speed and arrival
  time for 22 CMEs (in 2008-2012) to the corresponding interplanetary
  coronal mass ejection (ICME) parameters at in situ observatories
  (STEREO PLASTIC/IMPACT, Wind SWE/MFI). The list consists of front-
  and backsided, slow and fast CMEs (up to 2700 km s<SUP>-1</SUP>). We
  track the CMEs to 34.9 ± 7.1 deg elongation from the Sun with J maps
  constructed using the SATPLOT tool, resulting in prediction lead times
  of -26.4 ± 15.3 hr. The geometrical models we use assume different
  CME front shapes (fixed-Φ, harmonic mean, self-similar expansion) and
  constant CME speed and direction. We find no significant superiority
  in the predictive capability of any of the three methods. The absolute
  difference between predicted and observed ICME arrival times is 8.1 ±
  6.3 hr (rms value of 10.9 hr). Speeds are consistent to within 284 ±
  288 km s<SUP>-1</SUP>. Empirical corrections to the predictions enhance
  their performance for the arrival times to 6.1 ± 5.0 hr (rms value
  of 7.9 hr), and for the speeds to 53 ± 50 km s<SUP>-1</SUP>. These
  results are important for Solar Orbiter and a space weather mission
  positioned away from the Sun-Earth line.

---------------------------------------------------------
Title: Morphology of an ICME-event derived by Multi-point in Situ
    and Heliospheric Imaging Data
Authors: Rollett, Tanja; Möstl, Christian; Temmer, Manuela; Veronig,
   Astrid M.; Frahm, Rudy A.; Davies, Jackie A.; Vrsnak, Bojan; Farrugia,
   Charles J.; Amerstorfer, Ute V.
2014EGUGA..1610892R    Altcode:
  We show the analysis of an outstanding fast interplanetary coronal
  mass ejection (ICME) of 07 March 2012, which has been observed
  stereoscopically from both STEREO spacecraft. Assuming self-similar
  expansion and constant direction of motion we derive the kinematical
  profiles for the eastern and the western part of the roughly
  Earth-directed ICME. As additional constraints we use the huge
  advantage of in situ measurements at various locations during the
  ICME's propagation, namely from Venus Express, Messenger, Wind and
  Mars Express. We found that the eastern part of the ICME had a much
  higher propagation speed than its western part. Using the drag-based
  model, a model for the propagation of ICMEs in the inner heliosphere,
  we analyzed the influence of the drag on both sides of the ICME due
  to the surrounding solar wind conditions. These different solar wind
  conditions could have been the reason for the differing velocities
  and therefore for a distortion of the ICME front. These studies are
  fundamental in order to deepen the understanding of ICME evolution
  and to enhance existing forecasting methods.

---------------------------------------------------------
Title: Connecting speeds, directions and arrival times of 22 coronal
    mass ejections from the Sun to 1 AU
Authors: Möstl, Christian; Amla, Keshav; Hall, Jeff R.; Liewer,
   Paulett C.; DeJong, Eric M.; Colaninno, Robin C.; Veronig, Astrid M.;
   Rollett, Tanja; Temmer, Manuela; Peinhart, Vanessa; Davies, Jackie
   A.; Lugaz, Noé; Liu, Ying; Farrugia, Charles J.; Luhmann, Janet G.;
   Vrsnak, Bojan; Harrison, Richard A.; Galvin, Antoinette B.
2014EGUGA..16.1755M    Altcode:
  Forecasting in situ properties of coronal mass ejections (CMEs) from
  remote images is expected to strongly enhance predictions of space
  weather, and is of general interest for studying the interaction of
  the solar wind with planetary environments. We study the feasibility of
  using a heliospheric imager (HI) instrument, which is able to image the
  solar wind density along the full Sun to 1 AU distance, for connecting
  remote images to in situ observations of CMEs. Such an instrument
  is currently in operation on each of the two STEREO spacecraft. We
  compare the predictions for speed and arrival time for 22 different
  CME events (between 2008-2012), each observed remotely by one STEREO
  spacecraft, to the interplanetary coronal mass ejection (ICME) speed and
  arrival time observed at in situ observatories (STEREO PLASTIC/IMPACT,
  Wind SWE/MFI). We use croissant modeling for STEREO/COR2, and with a
  single-spacecraft STEREO/HI instrument, we track each CME to 34.9 ± 7.1
  degree elongation from the Sun with J-maps constructed with the SATPLOT
  tool. We then fit geometrical models to each track, assuming different
  CME front shapes (Fixed-Φ, Harmonic Mean, Self-Similar Expansion),
  and constant CME speed and direction. We find no significant preference
  in the predictive capability for any of the three geometrical modeling
  methods used on the full event list, consisting of front- and backsided,
  slow and fast CMEs (up to 2700 km s-1). The absolute difference between
  predicted and observed ICME arrival times is 8.1 ± 6.4 hours (rms
  value of 10.9h), and speeds are consistent within 284 ± 291 km s-1,
  including the geometric effects of CME apex or flank encounters. We
  derive new empirical corrections to the imaging results, enhancing
  the performance of the arrival time predictions to 6.1 ± 5.0 hours
  (rms value of 7.9h), and the speed predictions to 53 ± 50 km s-1,
  for this particular set of events. The prediction lead time is around
  1 day (-26.4 ± 15.3h). CME directions given by the HI methods differ
  considerably, and biases are found on the order of 30-50 degree in
  heliospheric longitude, consistent with theoretical expectations. These
  results are of interest concerning future missions such as Solar Orbiter
  or a dedicated space weather mission positioned remotely from the Earth.

---------------------------------------------------------
Title: Comparative Study of MHD Modeling of the Background Solar Wind
Authors: Gressl, C.; Veronig, A. M.; Temmer, M.; Odstrčil, D.;
   Linker, J. A.; Mikić, Z.; Riley, P.
2014SoPh..289.1783G    Altcode: 2013arXiv1312.1220G
  Knowledge about the background solar wind plays a crucial role in
  the framework of space-weather forecasting. In-situ measurements
  of the background solar wind are only available for a few points in
  the heliosphere where spacecraft are located, therefore we have to
  rely on heliospheric models to derive the distribution of solar-wind
  parameters in interplanetary space. We test the performance of different
  solar-wind models, namely Magnetohydrodynamic Algorithm outside
  a Sphere/ENLIL (MAS/ENLIL), Wang-Sheeley-Arge/ENLIL (WSA/ENLIL),
  and MAS/MAS, by comparing model results with in-situ measurements
  from spacecraft located at 1 AU distance to the Sun (ACE, Wind). To
  exclude the influence of interplanetary coronal mass ejections
  (ICMEs), we chose the year 2007 as a time period with low solar
  activity for our comparison. We found that the general structure of the
  background solar wind is well reproduced by all models. The best model
  results were obtained for the parameter solar-wind speed. However,
  the predicted arrival times of high-speed solar-wind streams have
  typical uncertainties of the order of about one day. Comparison of
  model runs with synoptic magnetic maps from different observatories
  revealed that the choice of the synoptic map significantly affects
  the model performance.

---------------------------------------------------------
Title: Response of the Earth's thermosphere to interplanetary coronal
    mass ejections
Authors: Krauss, S.; Temmer, M.; Lammer, H.; Veronig, A.; Baur, O.;
   Pfleger, M.; Boudjada, M. Y.; Leitzinger, M.; Besser, B. P.
2014EPSC....9..724K    Altcode:
  In this contribution we address the Earth's thermospheric response to
  interplanetary coronal mass ejections. We investigate several ICME
  events by means of neutral density measurements from the low-Earth
  orbiting satellites GRACE. Furthermore we correlate these observations
  with data from the ACE satellite located at L1 upstream of the Earth. By
  analyzing the data, high correlations between the neutral density and
  various combinations of ICME parameters can be found.

---------------------------------------------------------
Title: Asymmetry in the CME-CME Interaction Process for the Events
    from 2011 February 14-15
Authors: Temmer, M.; Veronig, A. M.; Peinhart, V.; Vršnak, B.
2014ApJ...785...85T    Altcode: 2014arXiv1402.6891T
  We present a detailed study of the interaction process of two coronal
  mass ejections (CMEs) successively launched on 2011 February 14 (CME1)
  and 2011 February 15 (CME2). Reconstructing the three-dimensional
  shape and evolution of the flux ropes, we verify that the two CMEs
  interact. The frontal structure of both CMEs, measured along different
  position angles (PAs) over the entire latitudinal extent, reveals
  differences in the kinematics for the interacting flanks and the
  apexes. The interaction process is strongly PA-dependent in terms of
  timing as well as kinematical evolution. The central interaction occurs
  along PA-100°, which shows the strongest changes in kinematics. During
  interaction, CME1 accelerates from ~400 km s<SUP>-1</SUP> to ~700 km
  s<SUP>-1</SUP> and CME2 decelerates from ~1300 km s<SUP>-1</SUP> to ~600
  km s<SUP>-1</SUP>. Our results indicate that a simplified scenario such
  as inelastic collision may not be sufficient to describe the CME-CME
  interaction. The magnetic field structures of the intertwining flux
  ropes and the momentum transfer due to shocks each play an important
  role in the interaction process.

---------------------------------------------------------
Title: Solar Magnetized Tornadoes: Rotational Motion in a Tornado-like
    Prominence
Authors: Su, Yang; Gömöry, Peter; Veronig, Astrid; Temmer, Manuela;
   Wang, Tongjiang; Vanninathan, Kamalam; Gan, Weiqun; Li, YouPing
2014ApJ...785L...2S    Altcode: 2013arXiv1312.5226S
  Su et al. proposed a new explanation for filament formation and
  eruption, where filament barbs are rotating magnetic structures driven
  by underlying vortices on the surface. Such structures have been noticed
  as tornado-like prominences when they appear above the limb. They may
  play a key role as the source of plasma and twist in filaments. However,
  no observations have successfully distinguished rotational motion of
  the magnetic structures in tornado-like prominences from other motions
  such as oscillation and counter-streaming plasma flows. Here we report
  evidence of rotational motions in a tornado-like prominence. The
  spectroscopic observations in two coronal lines were obtained from a
  specifically designed Hinode/EIS observing program. The data revealed
  the existence of both cold and million-degree-hot plasma in the
  prominence leg, supporting the so-called prominence-corona transition
  region. The opposite velocities at the two sides of the prominence and
  their persistent time evolution, together with the periodic motions
  evident in SDO/AIA dark structures, indicate a rotational motion of
  both cold and hot plasma with a speed of ~5 km s<SUP>-1</SUP>.

---------------------------------------------------------
Title: A Challenging Solar Eruptive Event of 18 November 2003 and
    the Causes of the 20 November Geomagnetic Superstorm. II. CMEs,
    Shock Waves, and Drifting Radio Bursts
Authors: Grechnev, V. V.; Uralov, A. M.; Chertok, I. M.; Slemzin,
   V. A.; Filippov, B. P.; Egorov, Y. I.; Fainshtein, V. G.; Afanasyev,
   A. N.; Prestage, N. P.; Temmer, M.
2014SoPh..289.1279G    Altcode: 2013arXiv1308.3010G
  We continue our study (Grechnev et al., 2013,
  doi:10.1007/s11207-013-0316-6; Paper I) on the 18 November 2003
  geoffective event. To understand possible impact on geospace of coronal
  transients observed on that day, we investigated their properties
  from solar near-surface manifestations in extreme ultraviolet, LASCO
  white-light images, and dynamic radio spectra. We reconcile near-surface
  activity with the expansion of coronal mass ejections (CMEs) and
  determine their orientation relative to the earthward direction. The
  kinematic measurements, dynamic radio spectra, and microwave and X-ray
  light curves all contribute to the overall picture of the complex event
  and confirm an additional eruption at 08:07 - 08:20 UT close to the
  solar disk center presumed in Paper I. Unusual characteristics of the
  ejection appear to match those expected for a source of the 20 November
  superstorm but make its detection in LASCO images hopeless. On the
  other hand, none of the CMEs observed by LASCO seem to be a promising
  candidate for a source of the superstorm being able to produce, at most,
  a glancing blow on the Earth's magnetosphere. Our analysis confirms free
  propagation of shock waves revealed in the event and reconciles their
  kinematics with "EUV waves" and dynamic radio spectra up to decameters.

---------------------------------------------------------
Title: A Challenging Solar Eruptive Event of 18 November 2003 and
    the Causes of the 20 November Geomagnetic Superstorm. I. Unusual
    History of an Eruptive Filament
Authors: Grechnev, V. V.; Uralov, A. M.; Slemzin, V. A.; Chertok,
   I. M.; Filippov, B. P.; Rudenko, G. V.; Temmer, M.
2014SoPh..289..289G    Altcode: 2013arXiv1304.7950G
  This is the first of four companion papers, which comprehensively
  analyze a complex eruptive event of 18 November 2003 in active region
  (AR) 10501 and the causes of the largest Solar Cycle 23 geomagnetic
  storm on 20 November 2003. Analysis of a complete data set, not
  considered before, reveals a chain of eruptions to which hard X-ray and
  microwave bursts responded. A filament in AR 10501 was not a passive
  part of a larger flux rope, as usually considered. The filament erupted
  and gave origin to a coronal mass ejection (CME). The chain of events
  was as follows: i) a presumable eruption at 07:29 UT accompanied by
  a not reported M1.2 class flare probably associated with the onset of
  a first southeastern CME (CME1), which most likely is not responsible
  for the superstorm; ii) a confined eruption (without a CME) at 07:41 UT
  (M3.2 flare) that destabilized the large filament; iii) the filament
  acceleration around 07:56 UT; iv) the bifurcation of the eruptive
  filament that transformed into a large "cloud"; v) an M3.9 flare in
  AR 10501 associated to this transformation. The transformation of the
  filament could be due to the interaction of the eruptive filament with
  the magnetic field in the neighborhood of a null point, located at a
  height of about 100 Mm above the complex formed by ARs 10501, 10503,
  and their environment. The CORONAS-F/SPIRIT telescope observed the
  cloud in 304 Å as a large Y-shaped darkening, which moved from the
  bifurcation region across the solar disk to the limb. The masses and
  kinematics of the cloud and the filament were similar. Remnants of
  the filament were not clearly observed in the second southwestern CME
  (CME2), previously regarded as a source of the 20 November geomagnetic
  storm. These facts do not support a simple scenario, in which the
  interplanetary magnetic cloud is considered as a flux rope formed from
  a structure initially associated with the pre-eruption filament in AR
  10501. Observations suggest a possible additional eruption above the
  bifurcation region close to solar disk center between 08:07 and 08:17
  UT, which could be the source of the 20 November superstorm.

---------------------------------------------------------
Title: Kinematics of Interacting ICMEs and Related Forbush Decrease:
    Case Study
Authors: Maričić, D.; Vršnak, B.; Dumbović, M.; Žic, T.; Roša,
   D.; Hržina, D.; Lulić, S.; Romštajn, I.; Bušić, I.; Salamon, K.;
   Temmer, M.; Rollett, T.; Veronig, A.; Bostanjyan, N.; Chilingarian,
   A.; Mailyan, B.; Arakelyan, K.; Hovhannisyan, A.; Mujić, N.
2014SoPh..289..351M    Altcode:
  We study heliospheric propagation and some space weather aspects of
  three Earth-directed interplanetary coronal mass ejections (ICMEs),
  successively launched from the active region AR 11158 in the period
  13 - 15 February 2011. From the analysis of the ICME kinematics,
  morphological evolution, and in situ observations, we infer that the
  three ICMEs interacted on their way to Earth, arriving together at 1
  AU as a single interplanetary disturbance. Detailed analysis of the
  in situ data reveals complex internal structure of the disturbance,
  where signatures of the three initially independent ICMEs could be
  recognized. The analysis also reveals compression and heating of the
  middle ICME, as well as ongoing magnetic reconnection between the
  leading and the middle ICME. We present evidence showing that the
  propagation of these two, initially slower ICMEs, was boosted by the
  fastest, third ICME. Finally, we employ the ground-based cosmic ray
  observations, to show that this complex disturbance produced a single
  cosmic ray event, i.e., a simple Forbush decrease (FD). The results
  presented provide a better understanding of the ICME interactions and
  reveal effects that should be taken into account in forecasting of
  the arrival of such compound structures.

---------------------------------------------------------
Title: Identification of coronal holes and filament channels in
    SDO/AIA 193Å images via geometrical classification methods
Authors: Reiss, M.; Temmer, M.; Rotter, T.; Hofmeister, S. J.; Veronig,
   A. M.
2014CEAB...38...95R    Altcode: 2014arXiv1408.2777R
  In this study, we describe and evaluate shape measures for
  distinguishing between coronal holes and filament channels as
  observed in Extreme Ultraviolet (EUV) images of the Sun. For a set
  of well-observed coronal hole and filament channel regions extracted
  from SDO/AIA 193Å images we analyze their intrinsic morphology during
  the period 2011 to 2013, by using well known shape measures from the
  literature and newly developed geometrical classification methods. The
  results suggest an asymmetry in the morphology of filament channels
  giving support for the sheared arcade or weakly twisted flux rope model
  for filaments. We find that the proposed shape descriptors have the
  potential to reduce coronal hole classification errors and are eligible
  for screening techniques in order to improve the forecasting of solar
  wind high-speed streams from CH observations in solar EUV images.

---------------------------------------------------------
Title: Initiation of Coronal Mass Ejections by Sunspot Rotation
Authors: Valori, G.; Török, T.; Temmer, M.; Veronig, A. M.; van
   Driel-Gesztelyi, L.; Vršnak, B.
2014IAUS..300..201V    Altcode:
  We report observations of a filament eruption, two-ribbon flare, and
  coronal mass ejection (CME) that occurred in Active Region NOAA 10898
  on 6 July 2006. The filament was located South of a strong sunspot that
  dominated the region. In the evolution leading up to the eruption, and
  for some time after it, a counter-clockwise rotation of the sunspot of
  about 30 degrees was observed. We suggest that the rotation triggered
  the eruption by progressively expanding the magnetic field above the
  filament. To test this scenario, we study the effect of twisting
  the initially potential field overlying a pre-existing flux rope,
  using three-dimensional zero-β MHD simulations. We consider a magnetic
  configuration whose photospheric flux distribution and coronal structure
  is guided by the observations and a potential field extrapolation. We
  find that the twisting leads to the expansion of the overlying field. As
  a consequence of the progressively reduced magnetic tension, the flux
  rope quasi-statically adapts to the changed environmental field, rising
  slowly. Once the tension is sufficiently reduced, a distinct second
  phase of evolution occurs where the flux rope enters an unstable regime
  characterized by a strong acceleration. Our simulation thus suggests
  a new mechanism for the triggering of eruptions in the vicinity of
  rotating sunspots.

---------------------------------------------------------
Title: The Wave-Driver System of the Off-Disk Coronal Wave of 17
    January 2010
Authors: Temmer, M.; Vrsnak, B.; Veronig, A. M.
2013SoPh..287..441T    Altcode: 2012arXiv1207.2857T; 2012SoPh..tmp..194T
  We study the 17 January 2010 flare-CME-wave event by using
  STEREO/SECCHI-EUVI and -COR1 data. The observational study is combined
  with an analytic model that simulates the evolution of the coronal wave
  phenomenon associated with the event. From EUV observations, the wave
  signature appears to be dome shaped having a component propagating
  on the solar surface (\overline{v}≈280~km s^{-1}) as well as one
  off-disk (\overline{v}≈ 600~km s^{-1}) away from the Sun. The off-disk
  dome of the wave consists of two enhancements in intensity, which
  conjointly develop and can be followed up to white-light coronagraph
  images. Applying an analytic model, we derive that these intensity
  variations belong to a wave-driver system with a weakly shocked wave,
  initially driven by expanding loops, which are indicative of the early
  evolution phase of the accompanying CME. We obtain the shock standoff
  distance between wave and driver from observations as well as from
  model results. The shock standoff distance close to the Sun (&lt; 0.3
  R<SUB>⊙</SUB> above the solar surface) is found to rapidly increase
  with values of ≈ 0.03 - 0.09 R<SUB>⊙</SUB>, which gives evidence
  of an initial lateral (over)expansion of the CME. The kinematical
  evolution of the on-disk wave could be modeled using input parameters
  that require a more impulsive driver (duration t=90 s, acceleration
  a=1.7 km s<SUP>−2</SUP>) compared to the off-disk component (duration
  t=340 s, acceleration a=1.5 km s<SUP>−2</SUP>).

---------------------------------------------------------
Title: Initiation of Coronal Mass Ejections by Sunspot Rotation
Authors: Török, T.; Temmer, M.; Valori, G.; Veronig, A. M.; van
   Driel-Gesztelyi, L.; Vršnak, B.
2013SoPh..286..453T    Altcode: 2014arXiv1401.2922T
  We study a filament eruption, two-ribbon flare, and coronal mass
  ejection (CME) that occurred in NOAA Active Region 10898 on 6 July
  2006. The filament was located South of a strong sunspot that dominated
  the region. In the evolution leading up to the eruption, and for some
  time after it, a counter-clockwise rotation of the sunspot of about
  30 degrees was observed. We suggest that the rotation triggered the
  eruption by progressively expanding the magnetic field above the
  filament. To test this scenario, we study the effect of twisting
  the initially potential field overlying a pre-existing flux-rope,
  using three-dimensional zero-β MHD simulations. We first consider
  a relatively simple and symmetric system, and then study a more
  complex and asymmetric magnetic configuration, whose photospheric-flux
  distribution and coronal structure are guided by the observations and a
  potential field extrapolation. In both cases, we find that the twisting
  leads to the expansion of the overlying field. As a consequence of the
  progressively reduced magnetic tension, the flux-rope quasi-statically
  adapts to the changed environmental field, rising slowly. Once the
  tension is sufficiently reduced, a distinct second phase of evolution
  occurs where the flux-rope enters an unstable regime characterised by
  a strong acceleration. Our simulations thus suggest a new mechanism
  for the triggering of eruptions in the vicinity of rotating sunspots.

---------------------------------------------------------
Title: Formation of Coronal Shock Waves
Authors: Lulić, S.; Vršnak, B.; Žic, T.; Kienreich, I. W.; Muhr,
   N.; Temmer, M.; Veronig, A. M.
2013SoPh..286..509L    Altcode: 2013arXiv1303.2786L
  Magnetosonic wave formation driven by an expanding cylindrical
  piston is numerically simulated to obtain better physical insight
  into the initiation and evolution of large-scale coronal waves caused
  by coronal eruptions. Several very basic initial configurations are
  employed to analyze intrinsic characteristics of MHD wave formation
  that do not depend on specific properties of the environment. It turns
  out that these simple initial configurations result in piston/wave
  morphologies and kinematics that reproduce common characteristics of
  coronal waves. In the initial stage, the wave and the expanding source
  region cannot be clearly resolved; i.e. a certain time is needed before
  the wave detaches from the piston. Thereafter, it continues to travel
  as what is called a "simple wave." During the acceleration stage of the
  source region inflation, the wave is driven by the piston expansion, so
  its amplitude and phase-speed increase, whereas the wavefront profile
  steepens. At a given point, a discontinuity forms in the wavefront
  profile; i.e. the leading edge of the wave becomes shocked. The
  time/distance required for the shock formation is shorter for a more
  impulsive source-region expansion. After the piston stops, the wave
  amplitude and phase speed start to decrease. During the expansion,
  most of the source region becomes strongly rarefied, which reproduces
  the coronal dimming left behind the eruption. However, the density
  increases at the source-region boundary, and stays enhanced even after
  the expansion stops, which might explain stationary brightenings
  that are sometimes observed at the edges of the erupted coronal
  structure. Also, in the rear of the wave a weak density depletion
  develops, trailing the wave, which is sometimes observed as weak
  transient coronal dimming. Finally, we find a well-defined relationship
  between the impulsiveness of the source-region expansion and the wave
  amplitude and phase speed. The results for the cylindrical piston are
  also compared with the outcome for a planar wave that is formed by a
  one-dimensional piston, to find out how different geometries affect
  the evolution of the wave.

---------------------------------------------------------
Title: Imaging coronal magnetic-field reconnection in a solar flare
Authors: Su, Yang; Veronig, Astrid M.; Holman, Gordon D.; Dennis,
   Brian R.; Wang, Tongjiang; Temmer, Manuela; Gan, Weiqun
2013NatPh...9..489S    Altcode: 2013arXiv1307.4527S
  Magnetic-field reconnection is believed to play a fundamental role
  in magnetized plasma systems throughout the Universe, including
  planetary magnetospheres, magnetars and accretion disks around black
  holes. This letter presents extreme ultraviolet and X-ray observations
  of a solar flare showing magnetic reconnection with a level of clarity
  not previously achieved. The multi-wavelength extreme ultraviolet
  observations from SDO/AIA show inflowing cool loops and newly formed,
  outflowing hot loops, as predicted. RHESSI X-ray spectra and images
  simultaneously show the appearance of plasma heated to &gt;10MK at
  the expected locations. These two data sets provide solid visual
  evidence of magnetic reconnection producing a solar flare, validating
  the basic physical mechanism of popular flare models. However, new
  features are also observed that need to be included in reconnection
  and flare studies, such as three-dimensional non-uniform, non-steady
  and asymmetric evolution.

---------------------------------------------------------
Title: Solar TErrestrial Relations Observatory-A (STEREO-A) and
    PRoject for On-Board Autonomy 2 (PROBA2) Quadrature Observations of
    Reflections of Three EUV Waves from a Coronal Hole
Authors: Kienreich, I. W.; Muhr, N.; Veronig, A. M.; Berghmans, D.;
   De Groof, A.; Temmer, M.; Vršnak, B.; Seaton, D. B.
2013SoPh..286..201K    Altcode: 2012SoPh..tmp..138K
  We investigate the interaction of three consecutive large-scale coronal
  waves with a polar coronal hole, simultaneously observed on-disk by the
  Solar TErrestrial Relations Observatory (STEREO)-A spacecraft and on
  the limb by the PRoject for On-Board Autonomy 2 (PROBA2) spacecraft on
  27 January 2011. All three extreme ultraviolet (EUV) waves originate
  from the same active region, NOAA 11149, positioned at N30E15 in the
  STEREO-A field of view and on the limb in PROBA2. For the three primary
  EUV waves, we derive starting velocities in the range of ≈ 310 km
  s<SUP>−1</SUP> for the weakest up to ≈ 500 km s<SUP>−1</SUP>
  for the strongest event. Each large-scale wave is reflected at the
  border of the extended coronal hole at the southern polar region. The
  average velocities of the reflected waves are found to be smaller than
  the mean velocities of their associated direct waves. However, the
  kinematical study also reveals that in each case the ending velocity
  of the primary wave matches the initial velocity of the reflected
  wave. In all three events, the primary and reflected waves obey the
  Huygens-Fresnel principle, as the incident angle with ≈ 10° to
  the normal is of the same magnitude as the angle of reflection. The
  correlation between the speed and the strength of the primary EUV waves,
  the homologous appearance of both the primary and the reflected waves,
  and in particular the EUV wave reflections themselves suggest that the
  observed EUV transients are indeed nonlinear large-amplitude MHD waves.

---------------------------------------------------------
Title: Propagation of Interplanetary Coronal Mass Ejections: The
    Drag-Based Model
Authors: Vršnak, B.; Žic, T.; Vrbanec, D.; Temmer, M.; Rollett, T.;
   Möstl, C.; Veronig, A.; Čalogović, J.; Dumbović, M.; Lulić, S.;
   Moon, Y. -J.; Shanmugaraju, A.
2013SoPh..285..295V    Altcode: 2012SoPh..tmp..124V
  We present the "Drag-Based Model" (DBM) of heliospheric propagation
  of interplanetary coronal mass ejections (ICMEs). The DBM is based on
  the hypothesis that the driving Lorentz force, which launches a CME,
  ceases in the upper corona and that beyond a certain distance the
  dynamics becomes governed solely by the interaction of the ICME and
  the ambient solar wind. In particular, we consider the option where
  the drag acceleration has a quadratic dependence on the ICME relative
  speed, which is expected in a collisionless environment, where the
  drag is caused primarily by emission of magnetohydrodynamic (MHD)
  waves. In this paper we present the simplest version of DBM, where
  the equation of motion can be solved analytically, providing explicit
  solutions for the Sun-Earth ICME transit time and impact speed. This
  offers easy handling and straightforward application to real-time
  space-weather forecasting. Beside presenting the model itself, we
  perform an analysis of DBM performances, applying a statistical and
  case-study approach, which provides insight into the advantages and
  drawbacks of DBM. Finally, we present a public, DBM-based, online
  forecast tool.

---------------------------------------------------------
Title: Heliospheric Imaging of 3D Density Structures During the
    Multiple Coronal Mass Ejections of Late July to Early August 2010
Authors: Webb, D. F.; Möstl, C.; Jackson, B. V.; Bisi, M. M.; Howard,
   T. A.; Mulligan, T.; Jensen, E. A.; Jian, L. K.; Davies, J. A.; de
   Koning, C. A.; Liu, Y.; Temmer, M.; Clover, J. M.; Farrugia, C. J.;
   Harrison, R. A.; Nitta, N.; Odstrcil, D.; Tappin, S. J.; Yu, H. -S.
2013SoPh..285..317W    Altcode:
  It is usually difficult to gain a consistent global understanding
  of a coronal mass ejection (CME) eruption and its propagation
  when only near-Sun imagery and the local measurements derived from
  single-spacecraft observations are available. Three-dimensional (3D)
  density reconstructions based on heliospheric imaging allow us to
  "fill in" the temporal and spatial gaps between the near-Sun and in
  situ data to provide a truly global picture of the propagation and
  interactions of the CME as it moves through the inner heliosphere. In
  recent years the heliospheric propagation of dense structures has been
  observed and measured by the heliospheric imagers of the Solar Mass
  Ejection Imager (SMEI) and on the twin Solar TErrestrial RElations
  Observatory (STEREO) spacecraft. We describe the use of several 3D
  reconstruction techniques based on these heliospheric imaging data sets
  to distinguish and track the propagation of multiple CMEs in the inner
  heliosphere during the very active period of solar activity in late July
  - early August 2010. We employ 3D reconstruction techniques used at the
  University of California, San Diego (UCSD) based on a kinematic solar
  wind model, and also the empirical Tappin-Howard model. We compare
  our results with those from other studies of this active period,
  in particular the heliospheric simulations made with the ENLIL model
  by Odstrcil et al. (J. Geophys. Res., 2013) and the in situ results
  from multiple spacecraft provided by Möstl et al. (Astrophys. J.758,
  10 - 28, 2012). We find that the SMEI results in particular provide
  an overall context for the multiple-density flows associated with
  these CMEs. For the first time we are able to intercompare the 3D
  reconstructed densities with the timing and magnitude of in situ
  density structures at five spacecraft spread over 150° in ecliptic
  longitude and from 0.4 to 1 AU in radial distance. We also model the
  magnetic flux-rope structures at three spacecraft using both force-free
  and non-force-free modelling, and compare their timing and spatial
  structure with the reconstructed density flows.

---------------------------------------------------------
Title: The Height Evolution of the "True" Coronal Mass Ejection Mass
    derived from STEREO COR1 and COR2 Observations
Authors: Bein, B. M.; Temmer, M.; Vourlidas, A.; Veronig, A. M.;
   Utz, D.
2013ApJ...768...31B    Altcode: 2013arXiv1303.3372B
  Using combined STEREO-A and STEREO-B EUVI, COR1, and COR2 data, we
  derive deprojected coronal mass ejection (CME) kinematics and CME "true"
  mass evolutions for a sample of 25 events that occurred during 2007
  December to 2011 April. We develop a fitting function to describe the
  CME mass evolution with height. The function considers both the effect
  of the coronagraph occulter, at the beginning of the CME evolution,
  and an actual mass increase. The latter becomes important at about
  10-15 R <SUB>⊙</SUB> and is assumed to mostly contribute up to
  20 R <SUB>⊙</SUB>. The mass increase ranges from 2% to 6% per R
  <SUB>⊙</SUB> and is positively correlated to the total CME mass. Due
  to the combination of COR1 and COR2 mass measurements, we are able to
  estimate the "true" mass value for very low coronal heights (&lt;3 R
  <SUB>⊙</SUB>). Based on the deprojected CME kinematics and initial
  ejected masses, we derive the kinetic energies and propelling forces
  acting on the CME in the low corona (&lt;3 R <SUB>⊙</SUB>). The
  derived CME kinetic energies range between 1.0-66 × 10<SUP>23</SUP>
  J, and the forces range between 2.2-510 × 10<SUP>14</SUP> N.

---------------------------------------------------------
Title: 2.5D MHD Simulations of the Kelvin-Helmholtz Instability at
    CME-Boundaries in the Solar Corona
Authors: Möstl, Ute; Temmer, Manuela; Veronig, Astrid
2013EGUGA..15.4171M    Altcode:
  We discuss the observation of a coronal mass ejection (CME) by the
  Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory from
  2011 February 24. This CME with an embedded filament shows periodic
  vortex-like structures at the northern side of the filament boundary
  with a wavelength of approximately 14.4 Mm and a propagation speed of
  about 310 ± 20 km/s. The morphological analysis hints at structures
  produced by the Kelvin-Helmholtz (KH) instability on the boundary of the
  filament. We conduct 2.5D numerical simulations of the KH instability,
  whose results yield qualitative as well as quantitative agreements with
  the observations. Furthermore, we study the absence of KH vortex-like
  structures on the southern side of the filament boundary and find that
  a magnetic field component parallel to the boundary with a strength
  of about 20% of the total magnetic field has stabilizing effects
  resulting in an asymmetric development of the instability. This work
  receives funding from the Austrian Science Fund (FWF): P21051-N16,
  V195-N16 and P24092-N16.

---------------------------------------------------------
Title: The Kanzelhöhe Observatory
Authors: Pötzi, Werner; Temmer, Manuela; Veronig, Astrid;
   Hirtenfellner-Polanec, Wolfgang; Baumgartner, Dietmar
2013EGUGA..15.1459P    Altcode:
  Kanzelhöhe Observatory (KSO; kso.ac.at) located in the South of
  Austria is part of the Institute of Physics of the University of
  Graz. Since the early 1940s, the Sun has been observed in various
  layers and wavelengths. Currently, KSO provides high-cadence full-disk
  observations of the solar disk in three wavelengths: H-alpha line,
  Ca II K line, white light. Real-time images are published online. For
  scientific use, the data is processed, and immediately available to
  the scientific community after each observing day via the Kanzelhöhe
  Online Data Archive archive (KODA; kanzelhohe.uni-graz.at). KSO is part
  of the Global H-Alpha Network and is also one of the contributing
  stations for the international sunspot number. In the frame of
  ESA's Space Situational Awareness program, methods are currently
  under development for near-real image recognition with respect to
  solar flares and filaments. These data products will give valuable
  complementary information for the solar sources of space weather.

---------------------------------------------------------
Title: Assessing the Constrained Harmonic Mean Method for Deriving
    the Kinematics of ICMEs with a Numerical Simulation
Authors: Rollett, T.; Temmer, M.; Möstl, C.; Lugaz, N.; Veronig,
   A. M.; Möstl, U. V.
2013SoPh..283..541R    Altcode: 2013arXiv1301.6945R
  In this study we use a numerical simulation of an artificial coronal
  mass ejection (CME) to validate a method for calculating propagation
  directions and kinematical profiles of interplanetary CMEs (ICMEs). In
  this method observations from heliospheric images are constrained
  with in-situ plasma and field data at 1 AU. These data are used
  to convert measured ICME elongations into distance by applying the
  harmonic mean approach, which assumes a spherical shape of the ICME
  front. We used synthetic white-light images, similar to those observed
  by STEREO-A/HI, for three different separation angles between remote
  and in-situ spacecraft of 30<SUP>∘</SUP>, 60<SUP>∘</SUP>, and
  90<SUP>∘</SUP>. To validate the results of the method, the images were
  compared to the apex speed profile of the modeled ICME, as obtained
  from a top view. This profile reflects the "true" apex kinematics
  because it is not affected by scattering or projection effects. In
  this way it is possible to determine the accuracy of the method for
  revealing ICME propagation directions and kinematics. We found that
  the direction obtained by the constrained harmonic mean method is not
  very sensitive to the separation angle (30<SUP>∘</SUP> sep: ϕ=W7;
  60<SUP>∘</SUP> sep: ϕ=W12; 90<SUP>∘</SUP> sep: ϕ=W15; true dir.:
  E0/W0). For all three cases the derived kinematics agree relatively
  well with the real kinematics. The best consistency is obtained for the
  30<SUP>∘</SUP> case, while with growing separation angle the ICME
  speed at 1 AU is increasingly overestimated (30<SUP>∘</SUP> sep:
  ΔV<SUB>arr</SUB>≈− 50 km s<SUP>−1</SUP>, 60<SUP>∘</SUP> sep:
  ΔV<SUB>arr</SUB>≈+ 75 km s<SUP>−1</SUP>, 90<SUP>∘</SUP> sep:
  ΔV<SUB>arr</SUB>≈+ 125 km s<SUP>−1</SUP>). Especially for future
  L<SUB>4</SUB>/L<SUB>5</SUB> missions, the 60<SUP>∘</SUP> separation
  case is highly interesting in order to improve space-weather forecasts.

---------------------------------------------------------
Title: Evolution of CMEs in the inner heliosphere - observations
    versus models
Authors: Temmer, Manuela; Vrsnak, Bojan; Möstl, Christian; Veronig,
   Astrid; Rollett, Tanja; Bein, Bianca
2013EGUGA..15.1328T    Altcode:
  With the SECCHI instrument suite aboard STEREO, coronal mass ejections
  (CMEs) can be observed from multiple vantage points during their entire
  propagation all the way from the Sun to 1 AU. The propagation behavior
  of CMEs in the interplanetary space is mainly influenced by the ambient
  solar wind flow. CMEs that are faster than the ambient solar wind get
  decelerated, whereas slower ones are accelerated until the CME speed
  is finally adjusted to the solar wind speed. On a statistical basis,
  empirical models taking into account the drag force acting on CMEs,
  are able to describe the observed kinematical behaviors. For several
  well observed events, we will present a comparative study showing
  the kinematical evolution of CMEs derived from remote sensing and
  in situ data, as well as from empirical models using 2D and 3D input
  parameters. From this we aim to obtain the distance regime at which
  the solar wind drag force is dominating the CME propagation.

---------------------------------------------------------
Title: Forecasting coronal mass ejections at 1 AU using Heliospheric
    Imagers
Authors: Möstl, Christian; Amla, Keshav; Hall, Jeffrey R.; Liewer,
   Paulett C.; De Jong, Eric; Temmer, Manuela; Davies, Jackie A.; Lugaz,
   Noé; Rollett, Tanja; Veronig, Astrid M.; Farrugia, Charles J.; Liu,
   Ying; Luhmann, Janet G.; Galvin, Antoinette B.; Zhang, Tielong
2013EGUGA..15.1311M    Altcode:
  We study the feasibility of using a Heliospheric Imager (HI) instrument,
  such as STEREO/HI, for operational space weather forecasting of
  interplanetary coronal mass ejections (ICMEs) at 1 AU. We compare the
  predictions for speed and arrival time for about 20 ICME events, each
  observed remotely by one STEREO spacecraft, to the speed and arrival
  time observed at various in situ observatories. We use geometrical
  modeling, which means we approximate the ICME fronts with various shapes
  (Fixed-Phi, Harmonic Mean, Self-Similar Expansion). These models are
  applied to the time-elongation functions extracted from STEREO/SECCHI
  images with the SolarSoft SATPLOT package. We use these techniques for
  a single-spacecraft HI observer, and consequently assume constant ICME
  speed and direction. Partly, the configuration mimics the situation of
  a single HI observatory parked at the L4 or L5 point in the Sun-Earth
  system. For assessing the accuracy of these predictions we look at
  plasma and magnetic field in situ data by Wind (MFI, SWE instruments)
  and STEREO-A/B (IMPACT, PLASTIC) around 1 AU. Wherever possible we
  include ICME arrivals in the inner heliosphere (&lt; 1 AU), from the
  magnetic field data by Venus Express and MESSENGER. We also look at
  the ratio of prediction lead time to its accuracy, and see if there
  is a preferred value for the ICME width.

---------------------------------------------------------
Title: Radial evolution of magnetic cloud properties
Authors: Rollett, Tanja; Veronig, Astrid M.; Leitner, Martin; Vrsnak,
   Bojan; Möstl, Christian; Farrugia, Charles J.; Temmer, Manuela
2013EGUGA..15.2710R    Altcode:
  Magnetic clouds (MCs) are characterized as intervals of enhanced,
  smoothly rotating interplanetary magnetic field, low plasma beta and
  temperature in spacecraft in situ data and can be part of ICMEs. In
  this study we analyze the radial evolution of MCs using a sample of
  events detected by radial aligned spacecrafts at different heliocentric
  distances. The data-sets are fitted with a force-free, constant-alpha
  flux rope model. Using the outcome of this fitting model we calculate
  the estimated cross section diameter (assuming a cylindrical flux tube),
  the poloidal and the axial magnetic field, the current, the magnetic
  flux and the inductance. All these parameter are further studied as a
  function of heliocentric distance. Strong variations of the current or
  the magnetic flux could be a hint for magnetic reconnection between
  the MC and the solar wind. This work has received funding from the
  European Commission FP7 Project COMESEP (263252).

---------------------------------------------------------
Title: The Kelvin-Helmholtz Instability at Coronal Mass Ejection
Boundaries in the Solar Corona: Observations and 2.5D MHD Simulations
Authors: Möstl, U. V.; Temmer, M.; Veronig, A. M.
2013ApJ...766L..12M    Altcode: 2013arXiv1304.5884M
  The Atmospheric Imaging Assembly on board the Solar Dynamics Observatory
  observed a coronal mass ejection with an embedded filament on 2011
  February 24, revealing quasi-periodic vortex-like structures at
  the northern side of the filament boundary with a wavelength of
  approximately 14.4 Mm and a propagation speed of about 310 ± 20 km
  s<SUP>-1</SUP>. These structures could result from the Kelvin-Helmholtz
  instability occurring on the boundary. We perform 2.5D numerical
  simulations of the Kelvin-Helmholtz instability and compare the
  simulated characteristic properties of the instability with the
  observations, where we obtain qualitative as well as quantitative
  accordance. We study the absence of Kelvin-Helmholtz vortex-like
  structures on the southern side of the filament boundary and find that
  a magnetic field component parallel to the boundary with a strength of
  about 20% of the total magnetic field has stabilizing effects resulting
  in an asymmetric development of the instability.

---------------------------------------------------------
Title: The role of solar "tornadoes" and vortices in filament
    fromation and eruption
Authors: Su, Yang; Wang, Tongjiang; Veronig, Astrid; Temmer, Manuela;
   Gan, Weiqun
2013enss.confE..51S    Altcode:
  Solar magnetized "tornadoes" are rotating vertical magnetic
  structures in the corona probably driven by underlying vortex flows
  in the photosphere. They usually exist as a group and are related
  to filaments/prominences. Detailed case studies show that these
  tornadoes may play a distinct role in the supply of mass and twists
  to filaments. The findings could lead to a new explanation of filament
  formation and eruption.

---------------------------------------------------------
Title: Direct Observations of Coronal Magnetic Reconnection
Authors: Su, Yang; Veronig, Astrid; Dennis, Brian R.; Holman, Gordon
   D.; Wang, Tongjiang; Temmer, Manuela; Gan, Weiqun
2013enss.confE..53S    Altcode:
  Magnetic field reconnection is believed to play a fundamental role in
  magnetized plasma systems throughout the universe, but never before
  has it been so clearly demonstrated as in the EUV and X-ray movies
  of a GOES-C-class solar flare presented here. The multiwavelength EUV
  observations from SDO/AIA show the predicted inflowing cool loops and
  newly formed outflowing hot loops while simultaneous RHESSI X-ray
  spectra and images show the appearance of plasma heated to &gt;10
  MK at the expected locations. These two data sets provide solid
  visual evidence of magnetic reconnection producing a solar flare. The
  non-uniform, nonsteady, and asymmetric nature of the observed process,
  together with the measured reconnection rates, supports the so called
  flux-pile-up reconnection. These new features of plasma inflows should
  be included in reconnection and flare studies.

---------------------------------------------------------
Title: The Kanzelhöhe Online Data Archive
Authors: Pötzi, W.; Hirtenfellner-Polanec, W.; Temmer, M.
2013CEAB...37..655P    Altcode:
  The Kanzelhöhe Observatory provides high-cadence full-disk observations
  of solar activity phenomena like sunspots, flares and prominence
  eruptions on a regular basis. The data are available for download
  from the KODA (Kanzelhöhe Observatory Data Archive) which is freely
  accessible. The archive offers sunspot drawings back to 1950 and
  high cadence H-α data back to 1973. Images from other instruments,
  like white-light and CaIIK, are available since 2007 and 2010,
  respectively. In the following we describe how to access the archive
  and the format of the data.

---------------------------------------------------------
Title: Relation Between Coronal Hole Areas on the Sun and the Solar
    Wind Parameters at 1 AU
Authors: Rotter, T.; Veronig, A. M.; Temmer, M.; Vršnak, B.
2012SoPh..281..793R    Altcode: 2012SoPh..tmp..202R
  We analyze the relationship between the coronal hole (CH)
  characteristics on the Sun (area, position, and intensity levels)
  and the corresponding solar wind parameters (solar wind speed v,
  proton temperature T, proton density n, and magnetic field strength B)
  measured in situ at 1 AU with a 6-h time resolution. We developed a
  histogram-based intensity thresholding method to obtain fractional CH
  areas from SOHO/EIT 195 Å images. The algorithm was applied to 6-h
  cadence EIT 195 Å images for the year 2005, which were characterized
  by a low solar activity. In calculating well-defined peaks of the solar
  wind parameters corresponding to the peaks in CH area, we found that the
  solar wind speed v shows a high correlation with correlation coefficient
  cc=0.78, medium correlation for T and B with cc=0.41 and cc=0.41. No
  significant correlation was found with the proton density n. Applying
  an intensity-weighted CH area did not improve the relations, since
  the size and the mean intensity of the CH areas are not independent
  parameters but strongly correlated (cc=− 0.72). Comparison of the
  fractional CH areas derived from GOES/SXI and SOHO/EIT and the related
  solar wind predictions shows no systematic differences (cc=0.79).

---------------------------------------------------------
Title: Forecasting coronal mass ejections at 1 AU using Heliospheric
    Imagers
Authors: Moestl, C.; Amla, K.; Temmer, M.; Hall, J. R.; Liewer, P. C.;
   De Jong, E. M.; Davies, J.; Lugaz, N.; Rollett, T.; Veronig, A.; Liu,
   Y.; Farrugia, C. J.; Luhmann, J. G.; Galvin, A. B.; Zhang, T.
2012AGUFMSH31A2208M    Altcode:
  We study the feasibility of using a Heliospheric Imager (HI) instrument,
  such as STEREO/HI, for space weather forecasting of interplanetary
  coronal mass ejections (ICMEs) at 1 AU. We compare the predictions for
  speed and arrival time for ~15 ICME events, each observed remotely by
  one STEREO spacecraft, to the speed and arrival time observed at in
  situ observatories. We use three different models with varying ICME
  geometry, from point-like (Fixed-Phi) to a circle with a given width
  (Self-Similar-Expansion) to a very wide circle (Harmonic Mean). The
  models are fitted to density tracks on HI Jmaps with the SolarSoft
  SATPLOT tool. All these techniques assume constant ICME speed and
  direction. Partly, the configuration mimics the situation of a
  single HI observatory parked at the L4 or L5 point in the Sun-Earth
  system. We discuss problems associated with this study, such as CME-CME
  interactions leading to complicated Jmaps. For assessing the accuracy
  of these predictions we look at in situ data by Wind/ACE, STEREO-A/B,
  and Venus Express and MESSENGER. We also look at the ratio of prediction
  lead time to its accuracy, and see if there is a preferred value for
  the ICME width.

---------------------------------------------------------
Title: CMEs - interaction with the background solar wind and
    other CMEs
Authors: Temmer, M.
2012AGUFMSH21C..01T    Altcode:
  The propagation behavior of coronal mass ejections (CMEs) in the
  interplanetary space is mainly influenced by the ambient solar
  wind flow and can be expressed as drag force. CMEs that are faster
  than the ambient solar wind get decelerated, whereas slower ones are
  accelerated until the CME speed is finally adjusted to the solar wind
  speed. As solar activity is rising, active regions will emerge hosting
  enough energy to erupt in quick succession. CMEs heading into similar
  directions are expected to interact, which means (dramatic) changes in
  their kinematical behavior. With the SECCHI instrument suite aboard
  STEREO, CMEs can be observed during their entire propagation all
  the way from the Sun to 1 AU. Various 3D reconstruction techniques,
  developed over the recent years, are used to derive the propagation
  direction of CMEs which is essential to interpret the interaction/drag
  processes. The talk will summarize observations in EUV and white light,
  from the corona to the heliosphere, concerning the interaction of CMEs
  with the background solar wind and other CMEs.

---------------------------------------------------------
Title: Relation between the impulsive CME acceleration and the
    nonthermal flare characteristics
Authors: Veronig, A. M.; Berkebile-Stoiser, S.; Bein, B. M.; Temmer, M.
2012AGUFMSH54A..03V    Altcode:
  We investigate the relationship between the main acceleration phase of
  CMEs and the particle acceleration in the associated flares observed
  by RHESSI for a set of 37 impulsive flare-CME events. Both the CME peak
  velocity and peak acceleration yield distinct correlations with various
  parameters characterizing the flare-accelerated electron spectra. The
  highest correlation coefficient is obtained for the relation of the
  CME peak velocity and the total energy in accelerated electrons (c =
  0.85), supporting the idea that the acceleration of the CME and the
  particle acceleration in the associated flare draw their energy from
  a common source, probably magnetic reconnection in the current sheet
  behind the erupting structure. In general, the CME peak velocity shows
  somewhat higher correlations with the non-thermal flare parameters
  than the CME peak acceleration, except for the spectral index of the
  accelerated electron spectrum, which yields a higher correlation with
  the CME peak acceleration (c = -0.6), indicating that the hardness
  of the flare-accelerated electron spectrum is tightly coupled to
  the impulsive acceleration process of the rising CME structure. We
  also obtained high correlations between the CME initiation height h0
  and the non-thermal flare parameters, with the highest correlation
  of h0 to the spectral index δ of flare-accelerated electrons (c =
  0.8). This means that CMEs erupting at low coronal heights, i.e., in
  regions of stronger magnetic fields, are accompanied by flares that are
  more efficient at accelerating electrons to high energies. In 80% of the
  events, the non-thermal flare emission starts after the CME acceleration
  (on average 6 min), which corresponds to a mean current sheet length
  at the onset of magnetic reconnection of 21 ± 7 Mm. The flare hard
  X-ray peaks are well synchronized with the peak of the CME acceleration
  profile, and in 75% of the cases they occur within ±5 minutes. Our
  findings provide strong evidence for the tight coupling between the
  CME dynamics and the particle acceleration in the associated flare
  in impulsive events, with the total energy in accelerated electrons
  being closely correlated with the peak velocity (and thus the kinetic
  energy) of the CME, whereas the number of electrons accelerated to
  high energies is decisively related to the CME peak acceleration and
  the height of the pre-eruptive structure.

---------------------------------------------------------
Title: Deep Solar Activity Minimum 2007-2009: Solar Wind Properties
    and Major Effects on the Terrestrial Magnetosphere
Authors: Farrugia, C. J.; Harris, B. S.; Leitner, M.; Moestl, C.;
   Galvin, A. B.; Simunac, K.; Torbert, R. B.; Temmer, M.; Veronig, A.;
   Erkaev, N.; Szabo, A.; Ogilvie, K. W.; Luhmann, J. G.; Osherovich, V.
2012AGUFMSM41C2226F    Altcode:
  We discuss the temporal variations and frequency distributions of
  solar wind and IMF parameters during the solar minimum of 2007-2009
  from measurements returned by the IMPACT and PLASTIC instruments on
  STEREO-A. We find that the density and total field strength were
  significantly weaker than in the previous minimum. The Alfvén
  Mach number was higher than typical.This reflects the weakness of
  magnetohydrodynamic (MHD) forces, and has a direct effect on the
  solar wind-magnetosphere interactions. We then discuss two major
  aspects that this weak solar activity had on the magnetosphere,
  using data from textit{Wind} and ground-based observations: (a) the
  dayside contribution to the cross-polar cap potential (CPCP), and (b)
  the shapes of the magnetopause and bow shock. For (a) we find a low
  interplanetary electric field of 1.3 ± 0.9 mV m<SUP>-1</SUP> and a
  CPCP of 37.3 ± 20.2 kV. The auroral activity is closely correlated to
  the prevalent stream-stream interactions. We suggest that the Alfvén
  wave trains in the fast streams and Kelvin-Helmholtz instability were
  the predominant agents mediating the transfer of solar wind momentum
  and energy to the magnetosphere during this three-year period. For
  (b) we determine 328 magnetopause and 271 bow shock crossings made by
  textit{Geotail, Cluster 1}, and the THEMIS B and C spacecraft during
  a three-month interval when the daily averages of the magnetic and
  kinetic energy densities attained their lowest value during the three
  years under survey. We use the same numerical approach as in Fairfield's
  (textit{J. Geophys. Res.} 76, 7600, 1971) empirical model and compare
  our findings with three magnetopause models. The stand-off distance
  of the subsolar magnetopause and bow shock were 11.8 R<SUB>E</SUB>
  and 14.35 R<SUB>E</SUB>, respectively. When comparing with Fairfield's
  (1971) classic result, we find that the subsolar magnetosheath is
  thinner by ∼1 R<SUB>E</SUB>. This is mainly due to the low dynamic
  pressure which results in a sunward shift of the magnetopause The
  magnetopause is more flared than in Fairfield's model. By contrast
  the bow shock is less flared, and the latter is the result of weaker
  MHD forces.

---------------------------------------------------------
Title: Validating a new method for deriving the kinematics of ICMEs
    with a numerical simulation
Authors: Rollett, T.; Temmer, M.; Moestl, C.; Lugaz, N.; Veronig,
   A.; Moestl, U. V.
2012AGUFMSH31A2209R    Altcode:
  Using a numerical simulation of a very wide coronal mass ejection
  (CME) we validate a method for calculating propagation directions
  and kinematical profiles of interplanetary CMEs (ICMEs). In this
  method observations from heliospheric images are constrained with the
  in-situ arrival time at 1 AU. This additional boundary condition is
  used to calculate the propagation direction and to convert measured
  ICME elongations into distance by applying the Harmonic Mean approach
  that assumes a spherical shape of the ICME front. We use synthetic
  white light images, similar as observed by STEREO-A/HI, for three
  different separation angles between remote and in-situ spacecraft,
  of 30°, 60° and 90°. For validation, the results of the method are
  compared to the "true" speed profile of the modeled ICME, as obtained
  from top view density images, for every separation case. In this way
  it is possible to determine the accuracy of the method for revealing
  ICME propagation directions and kinematics. We found that the direction
  yield by the constrained Harmonic Mean method is not very sensitive
  on the separation angle. For all three cases the derived kinematics
  are in a relatively good agreement with the real kinematics. The best
  consistency is obtained for the 30° case, while with growing separation
  the ICME speed at 1 AU is increasingly overestimated. Especially for
  future L4/L5 missions the 60° separation case is highly interesting
  in order to improve space weather forecasts.

---------------------------------------------------------
Title: The Deflection of CMEs During Instances of CME-CME Interactions
Authors: Lugaz, N.; Farrugia, C. J.; Davies, J.; Moestl, C.; Temmer,
   M.; Davis, C. J.; Roussev, I. I.
2012AGUFMSH31A2211L    Altcode:
  The interaction of successive coronal mass ejections (CMEs) can
  be directly imaged by remote-sensing instruments such as the HIs
  onboard STEREO and the resulting transients can be measured in situ by
  spacecraft such as STEREO-A, STEREO-B, ACE and Wind. Here, we present
  the analysis of two successive CMEs from May 2010, observed to interact
  within HI1 field-of-view. During the interaction, the second CME
  (CME2) is found to decelerate and the first CME (CME1) is found to get
  compressed. At 1 AU, Wind observed a single, typical magnetic cloud-like
  ejecta. By combining the different observations, we determine that this
  event shows a clear instance of the deflection of two CMEs due to their
  collision in the heliosphere, and we estimate the deflection of CME1
  to be about 10 degrees in the longitudinal direction. The resulting
  ejecta at 1 AU has a duration in agreement with the previously proposed
  hypothesis that compressed CMEs may over-expand after the end of the
  interaction. We also discuss additional events of CME-CME interaction
  and relate the findings to previous simulation efforts.

---------------------------------------------------------
Title: The Deflection of the Two Interacting Coronal Mass Ejections
    of 2010 May 23-24 as Revealed by Combined in Situ Measurements and
    Heliospheric Imaging
Authors: Lugaz, N.; Farrugia, C. J.; Davies, J. A.; Möstl, C.; Davis,
   C. J.; Roussev, I. I.; Temmer, M.
2012ApJ...759...68L    Altcode: 2012arXiv1209.2359L
  In 2010 May 23-24, Solar Dynamics Observatory (SDO) observed the launch
  of two successive coronal mass ejections (CMEs), which were subsequently
  tracked by the SECCHI suite on board STEREO. Using the COR2 coronagraphs
  and the heliospheric imagers (HIs), the initial direction of both CMEs
  is determined to be slightly west of the Sun-Earth line. We derive the
  CME kinematics, including the evolution of the CME expansion until 0.4
  AU. We find that, during the interaction, the second CME decelerates
  from a speed above 500 km s<SUP>-1</SUP> to 380 km s<SUP>-1</SUP>, the
  speed of the leading edge of the first CME. STEREO observes a complex
  structure composed of two different bright tracks in HI2-A but only one
  bright track in HI2-B. In situ measurements from Wind show an "isolated"
  interplanetary CME, with the geometry of a flux rope preceded by a
  shock. Measurements in the sheath are consistent with draping around
  the transient. By combining remote-sensing and in situ measurements,
  we determine that this event shows a clear instance of deflection of
  two CMEs after their collision, and we estimate the deflection of the
  first CME to be about 10° toward the Sun-Earth line. The arrival time,
  arrival speed, and radius at Earth of the first CME are best predicted
  from remote-sensing observations taken before the collision of the
  CMEs. Due to the over-expansion of the CME after the collision, there
  are few, if any, signs of interaction in in situ measurements. This
  study illustrates that complex interactions during the Sun-to-Earth
  propagation may not be revealed by in situ measurements alone.

---------------------------------------------------------
Title: Deep Solar Activity Minimum 2007 - 2009: Solar Wind Properties
    and Major Effects on the Terrestrial Magnetosphere
Authors: Farrugia, C. J.; Harris, B.; Leitner, M.; Möstl, C.; Galvin,
   A. B.; Simunac, K. D. C.; Torbert, R. B.; Temmer, M. B.; Veronig,
   A. M.; Erkaev, N. V.; Szabo, A.; Ogilvie, K. W.; Luhmann, J. G.;
   Osherovich, V. A.
2012SoPh..281..461F    Altcode: 2012SoPh..tmp..222F
  We discuss the temporal variations and frequency distributions of
  solar wind and interplanetary magnetic field parameters during the
  solar minimum of 2007 - 2009 from measurements returned by the IMPACT
  and PLASTIC instruments on STEREO-A. We find that the density and
  total field strength were significantly weaker than in the previous
  minimum. The Alfvén Mach number was higher than typical. This
  reflects the weakness of magnetohydrodynamic (MHD) forces, and has a
  direct effect on the solar wind-magnetosphere interactions. We then
  discuss two major aspects that this weak solar activity had on the
  magnetosphere, using data from Wind and ground-based observations:
  i) the dayside contribution to the cross-polar cap potential (CPCP),
  and ii) the shapes of the magnetopause and bow shock. For i) we find a
  low interplanetary electric field of 1.3±0.9 mV m<SUP>−1</SUP> and
  a CPCP of 37.3±20.2 kV. The auroral activity is closely correlated to
  the prevalent stream-stream interactions. We suggest that the Alfvén
  wave trains in the fast streams and Kelvin-Helmholtz instability were
  the predominant agents mediating the transfer of solar wind momentum
  and energy to the magnetosphere during this three-year period. For
  ii) we determine 328 magnetopause and 271 bow shock crossings made
  by Geotail, Cluster 1, and the THEMIS B and C spacecraft during a
  three-month interval when the daily averages of the magnetic and kinetic
  energy densities attained their lowest value during the three years
  under survey. We use the same numerical approach as in Fairfield's
  (J. Geophys. Res.76, 7600, 1971) empirical model and compare our
  findings with three magnetopause models. The stand-off distance of the
  subsolar magnetopause and bow shock were 11.8 R<SUB>E</SUB> and 14.35
  R<SUB>E</SUB>, respectively. When comparing with Fairfield's (1971)
  classic result, we find that the subsolar magnetosheath is thinner
  by ∼1 R<SUB>E</SUB>. This is mainly due to the low dynamic pressure
  which results in a sunward shift of the magnetopause. The magnetopause
  is more flared than in Fairfield's model. By contrast the bow shock
  is less flared, and the latter is the result of weaker MHD forces.

---------------------------------------------------------
Title: Multi-point Shock and Flux Rope Analysis of Multiple
    Interplanetary Coronal Mass Ejections around 2010 August 1 in the
    Inner Heliosphere
Authors: Möstl, C.; Farrugia, C. J.; Kilpua, E. K. J.; Jian, L. K.;
   Liu, Y.; Eastwood, J. P.; Harrison, R. A.; Webb, D. F.; Temmer, M.;
   Odstrcil, D.; Davies, J. A.; Rollett, T.; Luhmann, J. G.; Nitta, N.;
   Mulligan, T.; Jensen, E. A.; Forsyth, R.; Lavraud, B.; de Koning,
   C. A.; Veronig, A. M.; Galvin, A. B.; Zhang, T. L.; Anderson, B. J.
2012ApJ...758...10M    Altcode: 2012arXiv1209.2866M
  We present multi-point in situ observations of a complex
  sequence of coronal mass ejections (CMEs) which may serve as
  a benchmark event for numerical and empirical space weather
  prediction models. On 2010 August 1, instruments on various
  space missions, Solar Dynamics Observatory/Solar and Heliospheric
  Observatory/Solar-TErrestrial-RElations-Observatory (SDO/SOHO/STEREO),
  monitored several CMEs originating within tens of degrees from the
  solar disk center. We compare their imprints on four widely separated
  locations, spanning 120° in heliospheric longitude, with radial
  distances from the Sun ranging from MESSENGER (0.38 AU) to Venus
  Express (VEX, at 0.72 AU) to Wind, ACE, and ARTEMIS near Earth and
  STEREO-B close to 1 AU. Calculating shock and flux rope parameters at
  each location points to a non-spherical shape of the shock, and shows
  the global configuration of the interplanetary coronal mass ejections
  (ICMEs), which have interacted, but do not seem to have merged. VEX
  and STEREO-B observed similar magnetic flux ropes (MFRs), in contrast
  to structures at Wind. The geomagnetic storm was intense, reaching
  two minima in the Dst index (≈ - 100 nT), and was caused by the
  sheath region behind the shock and one of two observed MFRs. MESSENGER
  received a glancing blow of the ICMEs, and the events missed STEREO-A
  entirely. The observations demonstrate how sympathetic solar eruptions
  may immerse at least 1/3 of the heliosphere in the ecliptic with their
  distinct plasma and magnetic field signatures. We also emphasize the
  difficulties in linking the local views derived from single-spacecraft
  observations to a consistent global picture, pointing to possible
  alterations from the classical picture of ICMEs.

---------------------------------------------------------
Title: Solar Magnetized "Tornadoes:" Relation to Filaments
Authors: Su, Yang; Wang, Tongjiang; Veronig, Astrid; Temmer, Manuela;
   Gan, Weiqun
2012ApJ...756L..41S    Altcode: 2012arXiv1208.0138S
  Solar magnetized "tornadoes," a phenomenon discovered in the solar
  atmosphere, appear as tornado-like structures in the corona but are
  rooted in the photosphere. Like other solar phenomena, solar tornadoes
  are a feature of magnetized plasma and therefore differ distinctly
  from terrestrial tornadoes. Here we report the first analysis of solar
  "tornadoes" (two papers which focused on different aspects of solar
  tornadoes were published in the Astrophysical Journal Letters and
  Nature, respectively, during the revision of this Letter). A detailed
  case study of two events indicates that they are rotating vertical
  magnetic structures probably driven by underlying vortex flows
  in the photosphere. They usually exist as a group and are related
  to filaments/prominences, another important solar phenomenon whose
  formation and eruption are still mysteries. Solar tornadoes may play
  a distinct role in the supply of mass and twists to filaments. These
  findings could lead to a new explanation of filament formation and
  eruption.

---------------------------------------------------------
Title: Impulsive Acceleration of Coronal Mass Ejections. II. Relation
    to Soft X-Ray Flares and Filament Eruptions
Authors: Bein, B. M.; Berkebile-Stoiser, S.; Veronig, A. M.; Temmer,
   M.; Vršnak, B.
2012ApJ...755...44B    Altcode: 2012arXiv1206.2144B
  Using high time cadence images from the STEREO EUVI, COR1, and COR2
  instruments, we derived detailed kinematics of the main acceleration
  stage for a sample of 95 coronal mass ejections (CMEs) in comparison
  with associated flares and filament eruptions. We found that CMEs
  associated with flares reveal on average significantly higher peak
  accelerations and lower acceleration phase durations, initiation
  heights, and heights, at which they reach their peak velocities and peak
  accelerations. This means that CMEs that are associated with flares are
  characterized by higher and more impulsive accelerations and originate
  from lower in the corona where the magnetic field is stronger. For CMEs
  that are associated with filament eruptions we found only for the CME
  peak acceleration significantly lower values than for events that were
  not associated with filament eruptions. The flare rise time was found
  to be positively correlated with the CME acceleration duration and
  negatively correlated with the CME peak acceleration. For the majority
  of the events the CME acceleration starts before the flare onset (for
  75% of the events) and the CME acceleration ends after the soft X-ray
  (SXR) peak time (for 77% of the events). In ~60% of the events, the
  time difference between the peak time of the flare SXR flux derivative
  and the peak time of the CME acceleration is smaller than ±5 minutes,
  which hints at a feedback relationship between the CME acceleration and
  the energy release in the associated flare due to magnetic reconnection.

---------------------------------------------------------
Title: Relation between the Coronal Mass Ejection Acceleration and
    the Non-thermal Flare Characteristics
Authors: Berkebile-Stoiser, S.; Veronig, A. M.; Bein, B. M.; Temmer, M.
2012ApJ...753...88B    Altcode:
  We investigate the relationship between the main acceleration phase
  of coronal mass ejections (CMEs) and the particle acceleration in
  the associated flares as evidenced in Reuven Ramaty High Energy
  Solar Spectroscopic Imager non-thermal X-rays for a set of 37
  impulsive flare-CME events. Both the CME peak velocity and peak
  acceleration yield distinct correlations with various parameters
  characterizing the flare-accelerated electron spectra. The highest
  correlation coefficient is obtained for the relation of the CME peak
  velocity and the total energy in accelerated electrons (c = 0.85),
  supporting the idea that the acceleration of the CME and the particle
  acceleration in the associated flare draw their energy from a common
  source, probably magnetic reconnection in the current sheet behind the
  erupting structure. In general, the CME peak velocity shows somewhat
  higher correlations with the non-thermal flare parameters than the CME
  peak acceleration, except for the spectral index of the accelerated
  electron spectrum, which yields a higher correlation with the CME
  peak acceleration (c ≈ -0.6), indicating that the hardness of the
  flare-accelerated electron spectrum is tightly coupled to the impulsive
  acceleration process of the rising CME structure. We also obtained
  high correlations between the CME initiation height h <SUB>0</SUB>
  and the non-thermal flare parameters, with the highest correlation of
  h <SUB>0</SUB> to the spectral index δ of flare-accelerated electrons
  (c ≈ 0.8). This means that CMEs erupting at low coronal heights,
  i.e., in regions of stronger magnetic fields, are accompanied by flares
  that are more efficient at accelerating electrons to high energies. In
  the majority of events (~80%), the non-thermal flare emission starts
  after the CME acceleration, on average delayed by ≈6 minutes, in line
  with the standard flare model where the rising flux rope stretches the
  field lines underneath until magnetic reconnection sets in. We find
  that the current sheet length at the onset of magnetic reconnection
  is 21 ± 7 Mm. The flare hard X-ray peaks are well synchronized with
  the peak of the CME acceleration profile, and in 75% of the cases they
  occur within ±5 minutes. Our findings provide strong evidence for the
  tight coupling between the CME dynamics and the particle acceleration
  in the associated flare in impulsive events, with the total energy in
  accelerated electrons being closely correlated with the peak velocity
  (and thus the kinetic energy) of the CME, whereas the number of
  electrons accelerated to high energies is decisively related to the
  CME peak acceleration and the height of the pre-eruptive structure.

---------------------------------------------------------
Title: The Kelvin-Helmholtz Instability at CME-Boundaries in the
Solar Corona: Observations and Preliminary 2.5D MHD Simulations
Authors: Moestl, Ute Verena; Temmer, M.; Veronig, A. M.
2012shin.confE..85M    Altcode:
  Just recently, the Solar Dynamics Observatory (SDO) observedfor the
  first time Kelvin-Helmholtz vortices at the boundary of acoronal mass
  ejection (CME). The importance of the Kelvin-Helmholtz instability might
  lie in its effect on the CME kinematics due to exerting a drag force
  via anomalous viscosity.We discuss the observation of a CME by SDO from
  February 24th2011. This event shows periodic vortex-like structures
  on the boundary to the filament. First analysis of these structures
  reveals a periodic appearance with a wavelength of approximately 14 Mm
  and a height of 3-4 Mm.Another striking feature of this observation
  is an apparent asymmetric evolution of the periodic structures on
  only one side of the boundary layer. This asymmetry is also seen in
  other observations. Such observed asymmetry could be due to different
  magnetic field directions, for example. We test this hypothesis and
  present results of preliminary 2.5D magnetohydrodynamic simulations
  of the February 24th 2011event using different input parameters for
  the plasma background. Our aim is to check if the observed structures
  can be produced by the Kelvin-Helmholtz instability and to investigate
  the effect of different magnetic field directions on the evolution of
  the instability.

---------------------------------------------------------
Title: Kinematics of Coronal Mass Ejections in the Inner Heliosphere
    Constrained with In Situ Signatures
Authors: Rollett, Tanja; Möstl, Christian; Temmer, Manuela; Veronig,
   Astrid; Farrugia, Charles J.
2012shin.confE..80R    Altcode:
  On the basis of the Harmonic Mean and Fixed-Phi methods we developed
  a new approach to derive kinematics and propagation directions of
  interplanetary coronal mass ejections (ICMEs). By combining remote
  observations performed by STEREO/HI with in situ measurements of the
  Wind and STEREO-B spacecraft at 1 AU, we make the derived kinematical
  ICME profiles as consistent as possible with in situ data. Within the
  limitations of the geometrical assumptions that are used for the shape
  of the ICME, the improved methods aim to isolate the kinematics from
  that part of the CME which is most probably directed towards the in
  situ spacecraft. The methods are applied and tested on observational
  data from well observed ICME events (1-6 June 2008, 13-18 February
  2009). This work has received funding from the European Commission
  FP7 Project COMESEP (263252).

---------------------------------------------------------
Title: Multi-point shock and flux rope analysis of multiple ICMEs
    around 2010 August 1 in the inner heliosphere
Authors: Moestl, Christian; Farrugia, C. J.; Kilpua, E. K. J.; Jian,
   L.; Liu, Y.; Jensen, L.; Mulligan, T.; Eastwood, J.; Rollett, T.;
   Temmer, M.; Luhmann, J. G.; Harrison, R.; Davies, J. A.; Webb, D.;
   Forsyth, R.; Lavraud, B.; Odstrcil, D.; de Koning, C. A.; Nitta, N.;
   Veronig, A. M.; Galvin, A. B.; Zhang, T. L.
2012shin.confE..77M    Altcode:
  We present multi-point in situ observations of a complex sequence
  of coronal mass ejections which may serve as a benchmark event for
  numerical and empirical space weather prediction models. On 2010 August
  1, instruments on various space missions (SDO/SOHO/STEREO) monitored
  repeated coronal mass ejections originating within tens of degrees from
  solar disk center. We compare their imprints on four widely separated
  locations, covering 120 degree in heliospheric longitude, with radial
  distances from the Sun ranging from MESSENGER (0.38 AU) to Venus Express
  (VEX, at 0.72 AU) to Wind, ACE and ARTEMIS near Earth and STEREO-B close
  to 1 AU. Calculating shock and flux rope parameters at each location
  points to a non-spherical shape of the shock, and shows the global
  configuration of the interplanetary coronal mass ejections (ICMEs),
  which have interacted but not merged, making individual identifications
  still possible. VEX and STEREO-B observed similar magnetic flux ropes,
  in contrast to the structures at Wind. The geomagnetic storm was
  moderate to major, reaching two minima in the Dst index, caused by the
  sheath region behind the shock and one of two observed magnetic flux
  ropes. MESSENGER received a glancing blow of the ICMEs, and the events
  missed STEREO-A entirely. The observations demonstrate how sympathetic
  solar eruptions may immerse at least 1/3 of the heliosphere in the
  ecliptic with their distinct plasma and magnetic field signatures
  and emphasize the difficulties in linking the local views derived
  from single-spacecraft observations to a consistent global picture,
  pointing to possible alterations from the classical picture of ICMEs.

---------------------------------------------------------
Title: Comparison of MHD Simulations of the Solar Wind with In-Situ
    Measurements
Authors: Gressl, Corinna; Veronig, A. M.; Temmer, M.; Odstrcil, D.
2012shin.confE..31G    Altcode:
  ENLIL is a time-dependent 3D MHD model to simulate the structure
  and evolution of the solar wind parameters in the inner and
  mid heliosphere. ENLIL can be coupled to the coronal models
  "Magnetohydrodynamics Around Sphere" (MAS) and "Wang-Sheeley-Arge"
  (WSA) which use synoptic magnetograms of the solar photosphere as input
  parameter. We tested the performance of the coupled models ENLIL/MAS and
  ENLIL/WSA by comparing the modeled solar wind speed, proton density,
  temperature, and radial and total magnetic field strength to in-situ
  measurements from Wind and ACE at 1 AU. For the comparison we chose the
  year 2005 as a time period with low solar activity. We requested model
  runs with the aim to produce a stationary solution of the background
  solar wind. All simulations were carried out by CCMC/NASA. For the
  analysis of the model results we extracted the data at the exact
  position of the spacecraft. We calculated correlation coefficients to
  quantify the agreement between model predictions and measurements. The
  accuracy of the predicted arrival times of solar wind structures was
  quantified by carrying out cross-correlations. The results show that
  ENLIL/MAS and ENLIL/WSA are able to simulate the general features of
  the background solar wind and to reproduce recurring structures in the
  heliosphere. The best results were obtained for the parameter solar
  wind speed. However, the predicted arrival times of high speed solar
  wind streams have typical uncertainties of the order of 1 - 1.5 days,
  and the absolute values of the magnetic field were systematically too
  low. The sector structure of the interplanetary magnetic field was
  well reproduced by both models.

---------------------------------------------------------
Title: CME acceleration and non-thermal flare characteristics
Authors: Berkebile-Stoiser, S.; Veronig, A. M.; Bein, B. M.; Temmer, M.
2012arXiv1205.2539B    Altcode:
  We investigate the relationship between the main acceleration phase
  of coronal mass ejections (CMEs) and the particle acceleration in
  the associated flares as evidenced in RHESSI non-thermal X-rays for
  a set of 37 impulsive flare-CME events. CME peak velocity and peak
  acceleration yield distinct correlations with various parameters
  characterizing the flare-accelerated electron spectra. The highest
  correlation coefficient is obtained for the relation of the CME peak
  velocity and the total energy in accelerated electrons (c = 0.85),
  supporting the idea that the acceleration of the CME and the particle
  acceleration in the associated flare draw their energy from a common
  source, probably magnetic reconnection in the current sheet behind
  the erupting structure. In general, the CME peak velocity shows
  somewhat higher correlations with the non-thermal flare parameters
  than the CME peak acceleration, except for the spectral index of the
  accelerated electron spectrum which yields a higher correlation with
  the CME peak acceleration (c = -0.6), indicating that the hardness
  of the flare-accelerated electron spectrum is tightly coupled to the
  impulsive acceleration process of the rising CME structure. We also
  obtained high correlations between the CME initiation height $h_0$
  and the non-thermal flare parameters, with the highest correlation
  of $h_0$ to the spectral index of flare-accelerated electrons (c =
  0.8). This means that CMEs erupting at low coronal heights, i.e.\
  in regions of stronger magnetic fields, are accompanied with flares
  which are more efficient to accelerate electrons to high energies. In
  the majority of events (80%), the non-thermal flare emission starts
  after the CME acceleration (6 min), giving a current sheet length at
  the onset of magnetic reconnection of 21 \pm 7 Mm. The flare HXR peaks
  are well synchronized with the peak of the CME acceleration profile.

---------------------------------------------------------
Title: An Analysis of the Origin and Propagation of the Multiple
    Coronal Mass Ejections of 2010 August 1
Authors: Harrison, R. A.; Davies, J. A.; Möstl, C.; Liu, Y.; Temmer,
   M.; Bisi, M. M.; Eastwood, J. P.; de Koning, C. A.; Nitta, N.; Rollett,
   T.; Farrugia, C. J.; Forsyth, R. J.; Jackson, B. V.; Jensen, E. A.;
   Kilpua, E. K. J.; Odstrcil, D.; Webb, D. F.
2012ApJ...750...45H    Altcode:
  On 2010 August 1, the northern solar hemisphere underwent significant
  activity that involved a complex set of active regions near central
  meridian with, nearby, two large prominences and other more distant
  active regions. This activity culminated in the eruption of four major
  coronal mass ejections (CMEs), effects of which were detected at Earth
  and other solar system bodies. Recognizing the unprecedented wealth of
  data from the wide range of spacecraft that were available—providing
  the potential for us to explore methods for CME identification and
  tracking, and to assess issues regarding onset and planetary impact—we
  present a comprehensive analysis of this sequence of CMEs. We show that,
  for three of the four major CMEs, onset is associated with prominence
  eruption, while the remaining CME appears to be closely associated
  with a flare. Using instrumentation on board the Solar Terrestrial
  Relations Observatory spacecraft, three of the CMEs could be tracked
  out to elongations beyond 50° their directions and speeds have been
  determined by various methods, not least to assess their potential for
  Earth impact. The analysis techniques that can be applied to the other
  CME, the first to erupt, are more limited since that CME was obscured
  by the subsequent, much faster event before it had propagated far from
  the Sun; we discuss the speculation that these two CMEs interact. The
  consistency of the results, derived from the wide variety of methods
  applied to such an extraordinarily complete data set, has allowed
  us to converge on robust interpretations of the CME onsets and their
  arrivals at 1 AU.

---------------------------------------------------------
Title: A Self-similar Expansion Model for Use in Solar Wind Transient
    Propagation Studies
Authors: Davies, J. A.; Harrison, R. A.; Perry, C. H.; Möstl, C.;
   Lugaz, N.; Rollett, T.; Davis, C. J.; Crothers, S. R.; Temmer, M.;
   Eyles, C. J.; Savani, N. P.
2012ApJ...750...23D    Altcode:
  Since the advent of wide-angle imaging of the inner heliosphere,
  a plethora of techniques have been developed to investigate the
  three-dimensional structure and kinematics of solar wind transients,
  such as coronal mass ejections, from their signatures in single-
  and multi-spacecraft imaging observations. These techniques, which
  range from the highly complex and computationally intensive to methods
  based on simple curve fitting, all have their inherent advantages and
  limitations. In the analysis of single-spacecraft imaging observations,
  much use has been made of the fixed phi fitting (FPF) and harmonic
  mean fitting (HMF) techniques, in which the solar wind transient is
  considered to be a radially propagating point source (fixed phi,
  FP, model) and a radially expanding circle anchored at Sun centre
  (harmonic mean, HM, model), respectively. Initially, we compare the
  radial speeds and propagation directions derived from application of
  the FPF and HMF techniques to a large set of STEREO/Heliospheric Imager
  (HI) observations. As the geometries on which these two techniques
  are founded constitute extreme descriptions of solar wind transients
  in terms of their extent along the line of sight, we describe a
  single-spacecraft fitting technique based on a more generalized model
  for which the FP and HM geometries form the limiting cases. In addition
  to providing estimates of a transient's speed and propagation direction,
  the self-similar expansion fitting (SSEF) technique provides, in theory,
  the capability to estimate the transient's angular extent in the plane
  orthogonal to the field of view. Using the HI observations, and also
  by performing a Monte Carlo simulation, we assess the potential of
  the SSEF technique.

---------------------------------------------------------
Title: STEREO-A and PROBA2 Quadrature Observations of Reflections
    of three EUV Waves from a Coronal Hole
Authors: Kienreich, Ines Waltraud; Muhr, Nicole; Veronig, Astrid;
   Berghmans, David; de Groof, Anik; Temmer, Manuela; Vršnak, Bojan;
   Seaton, Dan
2012arXiv1204.6472K    Altcode: 2012arXiv1204.6472W
  We investigate the interaction of three consecutive large-scale coronal
  waves with a polar coronal hole, simultaneously observed on-disk by the
  Solar TErrestrial Relations Observatory (STEREO)-A spacecraft and on
  the limb by the PRoject for On-Board Autonomy 2 (PROBA2) spacecraft on
  January 27, 2011. All three extreme-ultraviolet(EUV) waves originate
  from the same active region NOAA 11149 positioned at N30E15 in the
  STEREO-A field-of-view and on the limb in PROBA2. We derive for the
  three primary EUV waves start velocities in the range of ~310 km/s for
  the weakest up to ~500 km/s for the strongest event. Each large-scale
  wave is reflected at the border of the extended coronal hole at the
  southern polar region. The average velocities of the reflected waves
  are found to be smaller than the mean velocities of their associated
  direct waves. However, the kinematical study also reveals that in each
  case the end velocity of the primary wave matches the initial velocity
  of the reflected wave. In all three events the primary and reflected
  waves obey the Huygens-Fresnel principle, as the incident angle with
  ~10° to the normal is of the same size as the angle of reflection. The
  correlation between the speed and the strength of the primary EUV waves,
  the homologous appearance of both the primary and the reflected waves,
  and in particular the EUV wave reflections themselves implicate that the
  observed EUV transients are indeed nonlinear large-amplitude MHD waves.

---------------------------------------------------------
Title: The first STEREO multi-event: Numerical simulation of coronal
    mass ejections (CMEs) launched on August 1, 2010
Authors: Odstrcil, D.; de Koning, C. A.; Xie, H.; Moestl, C.;
   Temmer, M.; Jian, L.; Rouillard, A. P.; Davies, J. A.; Davis, C. J.;
   Harrison, R.
2012EGUGA..1414429O    Altcode:
  On 2010-08-01 at least four coronal mass ejections (CMEs) were observed
  by the Heliospheric Imagers (HIs) onboard STEREO spacecraft. These
  events originated at different parts of the solar corona and generated
  complex scenario of four mutually interacting CMEs. Real-time
  prediction of the arrival times to Earth failed and it is difficult
  to associate features observed by HIs with their solar sources and
  impacts at spacecraft. We use the heliospheric code ENLIL to show the
  global solution for various scenarios using fitted CME parameters
  from coronagraph observations by different techniques. We present
  the temporal profiles and synthetic white-light images that enables
  direct comparison with in-situ and remote observations. These results
  show that in addition to multi-perspective coronagraph observations,
  heliospheric imagers and numerical simulations are needed to understand
  and predict the impact of complex heliospheric disturbances.

---------------------------------------------------------
Title: CME-CME interaction during the 2010 August 1 events
Authors: Temmer, M.; Vrsnak, B.; Rollett, T.; Bein, B.; deKoning,
   C. A.; Liu, Y.; Bosman, E.; Davies, J. A.; Möstl, C.; Zic, T.;
   Veronig, A. M.; Bothmer, V.; Harrison, R.; Nitta, N.; Bisi, M.; Flor,
   O.; Eastwood, J.; Odstrcil, D.; Forsyth, R.
2012EGUGA..14.1677T    Altcode:
  We study a CME-CME interaction that occurred during the 2010 August 1
  events using STEREO/SECCHI data (COR and HI). The CMEs were Earth
  directed where clear signatures of magnetic flux ropes could be
  measured from in situ Wind data. To give evidence of the actual
  interaction we derive the direction of motion for both CMEs applying
  several independent methods. From this we obtain that both CMEs head
  into similar directions enabling us to actually observe the merging
  in the HI1 field-of-view (and rule out the possibility that this is
  just a line of sight effect). The full de-projected kinematics of the
  faster CME from Sun to Earth is derived when combining data points from
  remote observations with in situ parameters of the ICME measured at
  1 AU. We study the evolution of the kinematical profile of the faster
  CME by applying a drag based model.

---------------------------------------------------------
Title: CME mass evolution derived from stereoscopic observations of
    STEREO/SECCHI instruments COR1 and COR2
Authors: Bein, B.; Temmer, M.; Vourlidas, A.; Veronig, A.
2012EGUGA..14.7174B    Altcode:
  The STEREO mission consists of two nearly identical spacecraft STEREO-A
  and STEREO-B, which observe simultaneously the Sun from two different
  vantage points. We use observations from both coronagraphs, COR1 and
  COR2 of the SECCHI instrument suite aboard STEREO-A and STEREO-B,
  to derive the CME mass evolution for a height range from 1.4 to 15
  RSun. Due to the fact that we have observations from two different
  vantage points, we measure not only the projected mass but can
  estimate the 'true' CME mass evolution with height. We developed a
  fit function, which considers the mass increase based on the geometry
  of the instrument (mass hidden behind the occulter) and a possible
  'real' mass increase with height. The fit parameters are compared with
  characteristic CME quantities.

---------------------------------------------------------
Title: Deep Solar Activity Minimum 2007-2009: Solar Wind Properties
    and Major Effects on the Terrestrial Magnetosphere
Authors: Farrugia, C. J.; Harris, B.; Leitner, M.; Möstl, C.; Galvin,
   A. B.; Simunac, K. D. C.; Torbert, R. B.; Temmer, M. B.; Veronig,
   A. M.; Erkaev, N. V.; Szabo, A.; Ogilvie, K. W.; Luhmann, J. G.;
   Osherovich, V. A.
2012EGUGA..14.6381F    Altcode:
  We discuss the temporal variations and frequency distributions of
  solar wind and interplanetary magnetic field parameters during the
  solar minimum of 2007- 2009 from measurements returned by the IMPACT
  and PLASTIC instruments on STEREO-A. We find that the density and
  total field strength were considerably weaker than in the previous
  minimum. The Alfvén Mach number was higher than typical. This reflects
  the weakness of magnetohydrodynamic (MHD) forces, and has a direct
  effect on the solar wind-magnetosphere interactions. We then discuss two
  major aspects that this weak solar activity had on the magnetosphere
  using data from Wind and ground-based observations: (a) the level
  of solar wind driving and the associated dayside contribution to the
  crosspolar cap potential (CPCP), and (b) the shapes of the magnetopause
  and bow shock. For (a) we find very weak interplanetary electric
  field (V xBz = -0.05 ± 0.83 mV/m) and a CPCP of 36.6 ± 18.2 kV. The
  auroral activity is closely correlated to the prevalent stream-stream
  interactions.We argue that the Alfvén waves in the fast streams and
  Kelvin-Helmholtz instability were the predominant agents mediating the
  transfer of solar wind momentum and energy to the magnetosphere during
  this 3-year period. For (b) we determine 328 magnetopause and 271 bow
  shock crossings made by the Cluster 1, Themis B and C spacecraft during
  a 3-month interval when the daily averages of the magnetic and kinetic
  energy densities attained their lowest value during the 3 years under
  survey. We use the same numerical approach as in Fairfield's (1971)
  empirical model and compare our findings with his classic result. The
  stand-off distance of the subsolar magnetopause and bow shock were
  11.8 RE and 14.35 RE, respectively, making the subsolar magnetosheath
  thinner by ≈ 1RE. This is mainly due to the low dynamic pressure
  which result in a sunward shift of the magnetopause The magnetopause
  is more flared than Fairfield's result. By contrast the bow shock is
  less flared, and the latter is the result of weaker MHD forces.

---------------------------------------------------------
Title: Characteristics of Kinematics of a Coronal Mass Ejection
    during the 2010 August 1 CME-CME Interaction Event
Authors: Temmer, Manuela; Vršnak, Bojan; Rollett, Tanja; Bein, Bianca;
   de Koning, Curt A.; Liu, Ying; Bosman, Eckhard; Davies, Jackie A.;
   Möstl, Christian; Žic, Tomislav; Veronig, Astrid M.; Bothmer, Volker;
   Harrison, Richard; Nitta, Nariaki; Bisi, Mario; Flor, Olga; Eastwood,
   Jonathan; Odstrcil, Dusan; Forsyth, Robert
2012ApJ...749...57T    Altcode: 2012arXiv1202.0629T
  We study the interaction of two successive coronal mass ejections (CMEs)
  during the 2010 August 1 events using STEREO/SECCHI COR and heliospheric
  imager (HI) data. We obtain the direction of motion for both CMEs by
  applying several independent reconstruction methods and find that the
  CMEs head in similar directions. This provides evidence that a full
  interaction takes place between the two CMEs that can be observed in the
  HI1 field of view. The full de-projected kinematics of the faster CME
  from Sun to Earth is derived by combining remote observations with in
  situ measurements of the CME at 1 AU. The speed profile of the faster
  CME (CME2; ~1200 km s<SUP>-1</SUP>) shows a strong deceleration over
  the distance range at which it reaches the slower, preceding CME (CME1;
  ~700 km s<SUP>-1</SUP>). By applying a drag-based model we are able
  to reproduce the kinematical profile of CME2, suggesting that CME1
  represents a magnetohydrodynamic obstacle for CME2 and that, after
  the interaction, the merged entity propagates as a single structure
  in an ambient flow of speed and density typical for quiet solar wind
  conditions. Observational facts show that magnetic forces may contribute
  to the enhanced deceleration of CME2. We speculate that the increase
  in magnetic tension and pressure, when CME2 bends and compresses the
  magnetic field lines of CME1, increases the efficiency of drag.

---------------------------------------------------------
Title: Calculation of CME kinematics and propagation directions by
    constraining STEREO HI-images with in situ signatures at 1 AU
Authors: Rollett, T.; Möstl, C.; Temmer, M.; Veronig, A. M.; Farrugia,
   C. J.; Biernat, H. K.
2012EGUGA..14.4778R    Altcode:
  We present a new approach to combine remote observations and in
  situ measurements by STEREO/HI and Wind, respectively, to derive the
  kinematics and propagation directions of interplanetary coronal mass
  ejections (ICMEs). We use two methods, Fixed-Phi and Harmonic Mean,
  to convert ICME elongations into distance. The ICME direction is
  constrained such that the ICME distance-time and speed-time profiles
  are most consistent with in situ measurements of the arrival time and
  speed at 1 AU. These methods are applied to two ICME events of 02 - 06
  June 2008 and 13 - 18 February 2009. Due to the geometrical assumptions
  HM delivers the propagation direction further away from the observing
  spacecraft with a mean difference of 25°. This work has received
  funding from the European Commission FP7 Project COMESEP (263252).

---------------------------------------------------------
Title: Constraining the Kinematics of Coronal Mass Ejections in the
    Inner Heliosphere with In-Situ Signatures
Authors: Rollett, T.; Möstl, C.; Temmer, M.; Veronig, A. M.; Farrugia,
   C. J.; Biernat, H. K.
2012SoPh..276..293R    Altcode: 2011SoPh..tmp..414R; 2011SoPh..tmp..412R; 2011arXiv1110.0300R
  We present a new approach to combine remote observations and in-situ
  data by STEREO/HI and Wind, respectively, to derive the kinematics
  and propagation directions of interplanetary coronal mass ejections
  (ICMEs). We use two methods, Fixed-ϕ (Fϕ) and Harmonic Mean (HM),
  to convert ICME elongations into distance, and constrain the ICME
  direction such that the ICME distance-time and velocity-time profiles
  are most consistent with in-situ measurements of the arrival time and
  velocity. The derived velocity-time functions from the Sun to 1 AU for
  the three events under study (1 - 6 June 2008, 13 - 18 February 2009,
  3 - 5 April 2010) do not show strong differences for the two extreme
  geometrical assumptions of a wide ICME with a circular front (HM)
  or an ICME of small spatial extent in the ecliptic (Fϕ). Due to the
  geometrical assumptions, HM delivers the propagation direction further
  away from the observing spacecraft with a mean difference of ≈ 25°.

---------------------------------------------------------
Title: Interactions between Coronal Mass Ejections Viewed in
    Coordinated Imaging and in situ Observations
Authors: Liu, Ying D.; Luhmann, Janet G.; Möstl, Christian;
   Martinez-Oliveros, Juan C.; Bale, Stuart D.; Lin, Robert P.; Harrison,
   Richard A.; Temmer, Manuela; Webb, David F.; Odstrcil, Dusan
2012ApJ...746L..15L    Altcode: 2012arXiv1201.2968L
  The successive coronal mass ejections (CMEs) from 2010 July 30 to
  August 1 present us the first opportunity to study CME-CME interactions
  with unprecedented heliospheric imaging and in situ observations from
  multiple vantage points. We describe two cases of CME interactions:
  merging of two CMEs launched close in time and overtaking of a preceding
  CME by a shock wave. The first two CMEs on August 1 interact close to
  the Sun and form a merged front, which then overtakes the July 30 CME
  near 1 AU, as revealed by wide-angle imaging observations. Connections
  between imaging observations and in situ signatures at 1 AU suggest
  that the merged front is a shock wave, followed by two ejecta observed
  at Wind which seem to have already merged. In situ measurements show
  that the CME from July 30 is being overtaken by the shock at 1 AU and
  is significantly compressed, accelerated, and heated. The interaction
  between the preceding ejecta and shock also results in variations
  in the shock strength and structure on a global scale, as shown by
  widely separated in situ measurements from Wind and STEREO B. These
  results indicate important implications of CME-CME interactions for
  shock propagation, particle acceleration, and space weather forecasting.

---------------------------------------------------------
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: Plasma Diagnostics of an EIT Wave Observed by Hinode/EIS
    and SDO/AIA
Authors: Veronig, A. M.; Gömöry, P.; Kienreich, I. W.; Muhr, N.;
   Vršnak, B.; Temmer, M.; Warren, H. P.
2011ApJ...743L..10V    Altcode: 2011arXiv1111.3505V
  We present plasma diagnostics of an Extreme-Ultraviolet
  Imaging Telescope (EIT) wave observed with high cadence in
  Hinode/Extreme-Ultraviolet Imaging Spectrometer (EIS) sit-and-stare
  spectroscopy and Solar Dynamics Observatory/Atmospheric Imaging
  Assembly imagery obtained during the HOP-180 observing campaign on 2011
  February 16. At the propagating EIT wave front, we observe downward
  plasma flows in the EIS Fe XII, Fe XIII, and Fe XVI spectral lines
  (log T ≈ 6.1-6.4) with line-of-sight (LOS) velocities up to 20
  km s<SUP>-1</SUP>. These redshifts are followed by blueshifts with
  upward velocities up to -5 km s<SUP>-1</SUP> indicating relaxation
  of the plasma behind the wave front. During the wave evolution, the
  downward velocity pulse steepens from a few km s<SUP>-1</SUP> up to 20
  km s<SUP>-1</SUP> and subsequently decays, correlated with the relative
  changes of the line intensities. The expected increase of the plasma
  densities at the EIT wave front estimated from the observed intensity
  increase lies within the noise level of our density diagnostics from
  EIS Fe XIII 202/203 Å line ratios. No significant LOS plasma motions
  are observed in the He II line, suggesting that the wave pulse was not
  strong enough to perturb the underlying chromosphere. This is consistent
  with the finding that no Hα Moreton wave was associated with the
  event. The EIT wave propagating along the EIS slit reveals a strong
  deceleration of a ≈ -540 m s<SUP>-2</SUP> and a start velocity of v
  <SUB>0</SUB> ≈ 590 km s<SUP>-1</SUP>. These findings are consistent
  with the passage of a coronal fast-mode MHD wave, pushing the plasma
  downward and compressing it at the coronal base.

---------------------------------------------------------
Title: Influence of the Ambient Solar Wind Flow on the Propagation
    Behavior of Interplanetary Coronal Mass Ejections
Authors: Temmer, Manuela; Rollett, Tanja; Möstl, Christian; Veronig,
   Astrid M.; Vršnak, Bojan; Odstrčil, Dusan
2011ApJ...743..101T    Altcode: 2011arXiv1110.0827T
  We study three coronal mass ejection (CME)/interplanetary coronal mass
  ejection (ICME) events (2008 June 1-6, 2009 February 13-18, and 2010
  April 3-5) tracked from Sun to 1 AU in remote-sensing observations
  of Solar Terrestrial Relations Observatory Heliospheric Imagers and
  in situ plasma and magnetic field measurements. We focus on the ICME
  propagation in interplanetary (IP) space that is governed by two
  forces: the propelling Lorentz force and the drag force. We address
  the question: which heliospheric distance range does the drag become
  dominant and the CME adjust to the solar wind flow. To this end,
  we analyze speed differences between ICMEs and the ambient solar
  wind flow as a function of distance. The evolution of the ambient
  solar wind flow is derived from ENLIL three-dimensional MHD model
  runs using different solar wind models, namely, Wang-Sheeley-Arge and
  MHD-Around-A-Sphere. Comparing the measured CME kinematics with the
  solar wind models, we find that the CME speed becomes adjusted to the
  solar wind speed at very different heliospheric distances in the three
  events under study: from below 30 R <SUB>⊙</SUB>, to beyond 1 AU,
  depending on the CME and ambient solar wind characteristics. ENLIL can
  be used to derive important information about the overall structure of
  the background solar wind, providing more reliable results during times
  of low solar activity than during times of high solar activity. The
  results from this study enable us to obtain greater insight into the
  forces acting on CMEs over the IP space distance range, which is an
  important prerequisite for predicting their 1 AU transit times.

---------------------------------------------------------
Title: Elliptical approximation for the fronts of ICMEs and
    application to STEREO events in August 2010 and February 2011
Authors: Moestl, C.; Davies, J. A.; Rollett, T.; Temmer, M.; Lugaz,
   N.; Farrugia, C. J.; Liu, Y.; Veronig, A. M.
2011AGUFMSH23C1971M    Altcode:
  Geo-effective solar eruptions can now be followed continuously
  from the Sun to 1 AU from a viewpoint far away from the Sun-Earth
  line (with STEREO/SECCHI), thus making it possible to link solar,
  heliospheric and in situ observations unambiguously. A very basic
  problem is that only the elongation of the interplanetary coronal mass
  ejection's (ICME) density enhancements, and not the radial distances,
  are measured by an observer when the ICME is propagating at large
  angles to the Sun. Additionally, this is complicated by the effects
  of Thomson scattering. Nevertheless, the community has worked so far
  with increasingly realistic geometrical approximations to convert the
  observed elongations to radial distance, such as Point-P (a circle
  around the Sun), Fixed-Phi (a point), Harmonic Mean (a circle always
  attached to the Sun at one end), and Self-Similar Expansion (a circle
  with a given angular width). We add to this an analytical formula
  which is based on an elliptical geometry (abbreviated EL), with the
  assumption, similar to HM and SSE, that the observer looks along the
  tangent of the ellipse which approximates the ICME front. In this way
  we still ignore Thomson-scattering, but otherwise the free parameters
  direction, angular width and aspect ratio allow more freedom to derive
  ICME radial distances and speeds from heliospheric imager observations,
  which should improve the consistency with in situ ICME observations
  and the CME directions and speeds in coronagraphs. An application to
  combined STEREO heliospheric imager and multi-point in situ observations
  of the multiple ICME events on 1-4 August 2010 and 15-17 February 2011
  is presented, and the possibility of using EL for real-time forecasts
  by means of inverse fitting and triangulation is discussed.

---------------------------------------------------------
Title: Propagation behavior of interplanetary CMEs: driving versus
    drag force
Authors: Temmer, M.; Rollett, T.; Moestl, C.; Veronig, A. M.;
   Vrsnak, B.
2011AGUFMSH23C1968T    Altcode:
  The evolution of coronal mass ejections (CMEs) is governed by the
  Lorentz and the drag force. Initially, the CME is launched and driven
  by the Lorentz force, whereas the drag force owing to the ambient solar
  wind controls the CME kinematics as it propagates into interplanetary
  (IP) space. The subject of the current study is to infer a heliospheric
  distance at which the drag force starts to prevail over the driving
  force. With the SECCHI instrument suite aboard STEREO, CMEs can be
  observed during their entire propagation all the way from Sun to 1
  AU. In combination with in-situ measurements at 1 AU we are able to
  derive the direction and speed of a CME. This information is used as
  input to derive the kinematical behavior of well observed CME events
  in the IP distance regime, which is subsequently compared to the output
  from ENLIL (NASA/CCMC) MHD model runs for the ambient solar wind flow.

---------------------------------------------------------
Title: Interaction between Coronal Mass Ejections Viewed in
    Coordinated Imaging and In Situ Observations
Authors: Liu, Y.; Luhmann, J. G.; Moestl, C.; Martinez Oliveros,
   J. C.; Harrison, R.; Temmer, M.; Bale, S.; Lin, R. P.
2011AGUFMSH23C1973L    Altcode:
  Interaction between coronal mass ejections (CMEs), which is expected
  to be a frequent phenomenon, has important implications for both
  space weather and basic plasma physics. First, the interaction alters
  the global heliospheric configuration, which may lead to favorable
  conditions for geomagnetic storm generation. Second, the interaction
  implies significant energy and momentum transfer between the interacting
  CMEs where magnetic reconnection may take place. Third, in case a
  shock is driven by the trailing CME, interesting physical processes
  may occur when the shock is propagating through the preceding one,
  such as modifications in the shock strength, particle intensity and
  transport. There are successive CMEs on July 30 - August 1, 2011,
  which presents us the first opportunity to study CME-CME interaction
  with unprecedented heliospheric imaging and in situ observations from
  a fleet of spacecraft. The first two CMEs on August 1 interact close
  to the Sun and form a merged front, which then overtakes the July
  30 CME near 1 AU, as revealed by wide-angle imaging observations. In
  situ measurements indicate that the first two CMEs on August 1 seem
  to have already merged at 0.7 and 1 AU, and at 1 AU their shock is
  propagating into the CME from July 30. We will report and discuss the
  CME-CME interaction signatures from the coordinated imaging and in
  situ observations in this presentation.

---------------------------------------------------------
Title: Validation of a New Method to Derive Sun-to-1 AU Kinematics
    of ICMEs with a Numerical Simulation
Authors: Rollett, T.; Moestl, C.; Lugaz, N.; Temmer, M.; Veronig, A. M.
2011AGUFMSH23C1970R    Altcode:
  The Heliospheric Imagers (HI) aboard the NASA STEREO mission offer the
  possibility to follow coronal mass ejections (CMEs) continuously on
  their way from close to the Sun up to ~ 1 AU. The interpretation of
  these images is challenging because line-of-sight as well as Thomson
  scattering effects influence the white-light signal. There are different
  methods to derive the velocity profiles and propagation directions of
  CMEs in the interplanetary space, e.g. Fixed-Φ (Kahler and Webb, 2007)
  and Harmonic Mean (Lugaz, Vourlidas and Roussev, 2009), which make the
  assumptions of a point like structure and a circle shaped front of the
  CME, respectively. These two approaches can be constrained using in situ
  measurements at 1 AU as shown in Rollett et al. (2011). To validate the
  applied methods, we perform the same procedures for a simulated CME as
  modeled in the space weather modeling framework (SWMF, Toth, et al.,
  2005). The measurements are outlined for synthetic HI images (Lugaz et
  al., 2005) at different observing points. The research leading to these
  results has received funding from the European Union Seventh Framework
  Programme (FP7/2007-2013) under grant agreement no. 263252 [COMESEP].

---------------------------------------------------------
Title: The first STEREO multi-event: Numerical simulation of coronal
    mass ejections (CMEs) launched on August 1, 2010
Authors: Odstrcil, D.; de Koning, C. A.; Xie, H.; Moestl, C.;
   Temmer, M.; Jian, L.; Rouillard, A. P.; Davies, J. A.; Davis, C. J.;
   Harrison, R.
2011AGUFMSH32A..03O    Altcode:
  On 2010-08-01 at least four coronal mass ejections (CMEs) were observed
  by the Heliospheric Imagers (HIs) onboard STEREO spacecraft. These
  events originated at different parts of the solar corona and generated
  complex scenario of four mutually interacting CMEs. Real-time
  prediction of the arrival times to Earth failed and it is difficult
  to associate features observed by HIs with their solar sources and
  impacts at spacecraft. We use the heliospheric code ENLIL to show
  the global solution for two scenarios using fitted CME parameters
  from coronagraph observations by two different techniques. We present
  the temporal profiles and synthetic white-light images that enables
  direct comparison with in-situ and remote observations. These results
  show that in addition to multi-perspective coronagraph observations,
  heliospheric imagers and numerical simulations are needed to understand
  and predict the impact of complex heliospheric disturbances.

---------------------------------------------------------
Title: Comparison between MHD modeled and in situ measured solar
    wind parameters
Authors: Gressl, C.; Veronig, A. M.; Temmer, M.; Moestl, C.
2011AGUFMSH23C1977G    Altcode:
  The numerical MHD model ENLIL enables us to simulate the solar wind
  conditions from Sun to 1 AU based on synoptic magnetograms over an
  entire Carrington rotation (runs are performed at the NASA/CCMC and
  are available on request under http://ccmc.gsfc.nasa.gov/). We use
  ENLIL for the inner-heliosphere coupled with the coronal model MAS
  (MHD-Around-A-Sphere) and the combined empirical and physics-based
  model WSA (Wang-Sheeley-Arge), respectively, to extract solar wind
  parameters at the distance of 1AU. The results from the simulation are
  compared to measured solar wind parameters at 1AU from ACE and Wind
  spacecraft. The study aims to test the accuracy and reliability for
  forecasting solar wind parameters like density, speed, temperature, and
  magnetic field from numerical models on time scales smaller than 1 day.

---------------------------------------------------------
Title: Arrival Time Calculation for Interplanetary Coronal Mass
    Ejections with Circular Fronts and Application to STEREO Observations
    of the 2009 February 13 Eruption
Authors: Möstl, C.; Rollett, T.; Lugaz, N.; Farrugia, C. J.; Davies,
   J. A.; Temmer, M.; Veronig, A. M.; Harrison, R. A.; Crothers, S.;
   Luhmann, J. G.; Galvin, A. B.; Zhang, T. L.; Baumjohann, W.; Biernat,
   H. K.
2011ApJ...741...34M    Altcode: 2011arXiv1108.0515M
  One of the goals of the NASA Solar TErestrial RElations Observatory
  (STEREO) mission is to study the feasibility of forecasting the
  direction, arrival time, and internal structure of solar coronal
  mass ejections (CMEs) from a vantage point outside the Sun-Earth
  line. Through a case study, we discuss the arrival time calculation
  of interplanetary CMEs (ICMEs) in the ecliptic plane using data from
  STEREO/SECCHI at large elongations from the Sun in combination with
  different geometric assumptions about the ICME front shape [fixed-Φ
  (FP): a point and harmonic mean (HM): a circle]. These forecasting
  techniques use single-spacecraft imaging data and are based on the
  assumption of constant velocity and direction. We show that for the
  slow (350 km s<SUP>-1</SUP>) ICME on 2009 February 13-18, observed at
  quadrature by the two STEREO spacecraft, the results for the arrival
  time given by the HM approximation are more accurate by 12 hr than
  those for FP in comparison to in situ observations of solar wind
  plasma and magnetic field parameters by STEREO/IMPACT/PLASTIC, and by
  6 hr for the arrival time at Venus Express (MAG). We propose that the
  improvement is directly related to the ICME front shape being more
  accurately described by HM for an ICME with a low inclination of its
  symmetry axis to the ecliptic. In this case, the ICME has to be tracked
  to &gt;30° elongation to obtain arrival time errors &lt; ± 5 hr. A
  newly derived formula for calculating arrival times with the HM method
  is also useful for a triangulation technique assuming the same geometry.

---------------------------------------------------------
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: Coronal Dimmings and the Early Phase of a CME Observed with
    STEREO and Hinode/EIS
Authors: Miklenic, C.; Veronig, A. M.; Temmer, M.; Möstl, C.; Biernat,
   H. K.
2011SoPh..273..125M    Altcode: 2011arXiv1110.0362M; 2011SoPh..tmp..350M
  We investigate the early phase of the 13 February 2009 coronal
  mass ejection (CME). Observations with the twin STEREO spacecraft
  in quadrature allow us to compare for the first time in one and the
  same event the temporal evolution of coronal EUV dimmings, observed
  simultaneously on-disk and above-the-limb. We find that these dimmings
  are synchronized and appear during the impulsive acceleration phase of
  the CME, with the highest EUV intensity drop occurring a few minutes
  after the maximum CME acceleration. During the propagation phase two
  confined, bipolar dimming regions, appearing near the footpoints of a
  pre-flare sigmoid structure, show an apparent migration away from the
  site of the CME-associated flare. Additionally, they rotate around the
  `center' of the flare site, i.e., the configuration of the dimmings
  exhibits the same `sheared-to-potential' evolution as the postflare
  loops. We conclude that the motion pattern of the twin dimmings reflects
  not only the eruption of the flux rope, but also the ensuing stretching
  of the overlying arcade. Finally, we find that: i) the global-scale
  dimmings, expanding from the source region of the eruption, propagate
  with a speed similar to that of the leaving CME front; ii) the mass
  loss occurs mainly during the period of strongest CME acceleration. Two
  hours after the eruption Hinode/EIS observations show no substantial
  plasma outflow, originating from the `open' field twin dimming regions.

---------------------------------------------------------
Title: The LSO/KSO Hα prominence catalogue: cross-calibration of data
Authors: Rybák, J.; Gömöry, P.; Mačura, R.; Kučera, A.; Rušin,
   V.; Pötzi, W.; Baumgartner, D.; Hanslmeier, A.; Veronig, A.;
   Temmer, M.
2011CoSka..41..133R    Altcode:
  We present work on the extension of the homogeneous prominence
  catalogue created for the epoch 1967 — 2009 at the Lomnicky Peak
  Observatory (LSO) by incorporating new data acquired at the Kanzelhöhe
  Observatory for Solar and Environmental Research (KSO). We use data of
  20 Hα prominences observed almost simultaneously at both observatories
  during four days in August/September 2009 to analyze the significance
  of differences of the determined parameters used in the Hα prominence
  catalogue. A reduction of the data from KSO and adaptation of the
  resulting parameters to fit the parameters of the LSO catalogue confirm
  that no special homogenization is needed to create a common catalogue
  data set. Thus, we justified that the LSO catalogue could be extended
  onward in the future using a more comprehensive database of observations
  from KSO.

---------------------------------------------------------
Title: Analysis of Characteristic Parameters of Large-scale Coronal
    Waves Observed by the Solar-Terrestrial Relations Observatory/Extreme
    Ultraviolet Imager
Authors: Muhr, N.; Veronig, A. M.; Kienreich, I. W.; Temmer, M.;
   Vršnak, B.
2011ApJ...739...89M    Altcode:
  The kinematical evolution of four extreme ultraviolet waves,
  well observed by the Extreme Ultraviolet Imager on board the
  Solar-Terrestrial Relations Observatory (STEREO), is studied by visually
  tracking wave fronts as well as by a semi-automatized perturbation
  profile method, which leads to results matching each other within
  the error limits. The derived mean velocities of the events under
  study lie in the range of 220-350 km s<SUP>-1</SUP>. The fastest of
  the events (2007 May 19) reveals a significant deceleration of ≈ -
  190 m s<SUP>-2</SUP>, while the others are consistent with a constant
  velocity during wave propagation. The evolution of maximum-intensity
  values reveals initial intensification of 20%-70% and decays to original
  levels within 40-60 minutes, while the widths at half-maximum and
  full-maximum of the perturbation profiles broaden by a factor of two
  to four. The integral below the perturbation profile remains basically
  constant in two cases, while it shows a decrease by a factor of three
  to four in the other two cases. From the peak perturbation amplitudes,
  we estimate the corresponding magnetosonic Mach numbers M <SUB>ms</SUB>,
  which range from 1.08-1.21. The perturbation profiles reveal three
  distinct features behind the propagating wave fronts: coronal dimmings,
  stationary brightenings, and rarefaction regions. All features appear
  after the wave passage and only slowly fade away. Our findings indicate
  that the events under study are weak-shock fast-mode magnetohydrodynamic
  waves initiated by the CME lateral expansion.

---------------------------------------------------------
Title: Propagation and impact of multiple coronal mass ejections
    events on August 1 2010 in the heliosphere
Authors: Möstl, Christian; Farrugia, Charles J.; Harrison, Richard
   A.; Davies, J. A.; Kilpua, Emilia K. J.; Odstrcil, Dusan; Rollett,
   Tanja; Temmer, Manuela; Veronig, Astrid; Jian, Lan; Liu, Ying;
   Eastwood, Jonathan; Forsyth, Robert; Webb, David; Bisi, Mario M.;
   Jackson, Bernard V.; Mulligan, Tamitha; Jensen, Liz; Lavraud, Benoit;
   de Koning, Curt A.; Nitta, Nariaki; Luhmann, Janet; Galvin, Antoinette
   B.; Zhang, Tielong
2011sdmi.confE..69M    Altcode:
  On August 1 2010 a large region of the solar northern hemisphere
  displayed major activity involving a complex set of central meridian and
  remote active regions, and two large prominence channels (Schrijver
  and Title, JGR, 2011). We witnessed the eruption of four coronal
  mass ejections (CMEs) which partly impacted Earth and lead to one
  of the first geomagnetic storms of the new solar cycle. We present an
  overview of the results of several analyses exploiting the extraordinary
  completeness of the imaging data (SDO/STEREO/SOHO) in combination with
  numerical simulations (ENLIL) and in situ observations. The imprints of
  the CMEs, including a prior event on July 30, were observed in situ in
  an almost laboratory-like configuration at 4 widely separated locations
  spanning over 120 degrees of heliospheric longitude (STEREO-B, Venus
  Express, ACE/Wind, ARTEMIS, and MESSENGER). The CME density enhancements
  could be followed with the STEREO-A/HI and Coriolis/SMEI instruments
  continuously from the Sun to 1 AU. Evidences of CME-CME interactions
  and resulting overlapping tracks in Jmaps make the analysis complex,
  but nevertheless we find robust interpretations for linking two magnetic
  flux ropes at Earth, one of them geo-effective and including elevated
  alpha particles related to possible filament material, to their solar
  counterparts. Additionally, we discuss the relationship between the
  in situ observations and the global picture given by the ENLIL model.

---------------------------------------------------------
Title: Solar wind high-speed streams and related geomagnetic activity
    in the declining phase of solar cycle 23
Authors: Verbanac, G.; Vršnak, B.; Živković, S.; Hojsak, T.;
   Veronig, A. M.; Temmer, M.
2011A&A...533A..49V    Altcode:
  Context. Coronal holes (CHs) are the source of high-speed streams
  (HSSs) in the solar wind, whose interaction with the slow solar wind
  creates corotating interaction regions (CIRs) in the heliosphere. <BR
  /> Aims: We investigate the magnetospheric activity caused by CIR/HSS
  structures, focusing on the declining phase of the solar cycle 23
  (years 2005 and 2006), when the occurrence rate of coronal mass
  ejections (CMEs) was low. We aim to (i) perform a systematic analysis
  of the relationship between the CH characteristics, basic parameters of
  HSS/CIRs, and the geomagnetic indices Dst, Ap and AE; (ii) study how the
  magnetospheric/ionospheric current systems behave when influenced by
  HSS/CIR; (iii) investigate if and how the evolution of the background
  solar wind from 2005 to 2006 affected the correlations between CH,
  CIR, and geomagnetic parameters. <BR /> Methods: The cross-correlation
  analysis was applied to the fractional CH area (CH) measured in the
  central meridian distance interval ± 10°, the solar wind velocity (V),
  the interplanetary magnetic field (B), and the geomagnetic indices Dst,
  Ap, and AE. <BR /> Results: The performed analysis shows that Ap and
  AE are better correlated with CH and solar wind parameters than Dst,
  and quantitatively demonstrates that the combination of solar wind
  parameters BV<SUP>2</SUP> and BV plays the central role in the process
  of energy transfer from the solar wind to the magnetosphere. <BR />
  Conclusions: We provide reliable relationships between CH properties,
  HSS/CIR parameters, and geomagnetic indices, which can be used in
  forecasting the geomagnetic activity in periods of low CME activity.

---------------------------------------------------------
Title: An Observational Overview of Solar Flares
Authors: Fletcher, L.; Dennis, B. R.; Hudson, H. S.; Krucker, S.;
   Phillips, K.; Veronig, A.; Battaglia, M.; Bone, L.; Caspi, A.; Chen,
   Q.; Gallagher, P.; Grigis, P. T.; Ji, H.; Liu, W.; Milligan, R. O.;
   Temmer, M.
2011SSRv..159...19F    Altcode: 2011SSRv..tmp..261F; 2011arXiv1109.5932F
  We present an overview of solar flares and associated phenomena,
  drawing upon a wide range of observational data primarily from the
  RHESSI era. Following an introductory discussion and overview of
  the status of observational capabilities, the article is split into
  topical sections which deal with different areas of flare phenomena
  (footpoints and ribbons, coronal sources, relationship to coronal mass
  ejections) and their interconnections. We also discuss flare soft X-ray
  spectroscopy and the energetics of the process. The emphasis is to
  describe the observations from multiple points of view, while bearing
  in mind the models that link them to each other and to theory. The
  present theoretical and observational understanding of solar flares is
  far from complete, so we conclude with a brief discussion of models,
  and a list of missing but important observations.

---------------------------------------------------------
Title: Impulsive Acceleration of Coronal Mass Ejections. I. Statistics
    and Coronal Mass Ejection Source Region Characteristics
Authors: Bein, B. M.; Berkebile-Stoiser, S.; Veronig, A. M.; Temmer,
   M.; Muhr, N.; Kienreich, I.; Utz, D.; Vršnak, B.
2011ApJ...738..191B    Altcode: 2011arXiv1108.0561B
  We use high time cadence images acquired by the STEREO EUVI and
  COR instruments to study the evolution of coronal mass ejections
  (CMEs) from their initiation through impulsive acceleration to the
  propagation phase. For a set of 95 CMEs we derived detailed height,
  velocity, and acceleration profiles and statistically analyzed
  characteristic CME parameters: peak acceleration, peak velocity,
  acceleration duration, initiation height, height at peak velocity,
  height at peak acceleration, and size of the CME source region. The CME
  peak accelerations we derived range from 20 to 6800 m s<SUP>-2</SUP>
  and are inversely correlated with the acceleration duration and the
  height at peak acceleration. Seventy-four percent of the events reach
  their peak acceleration at heights below 0.5 R <SUB>sun</SUB>. CMEs that
  originate from compact sources low in the corona are more impulsive and
  reach higher peak accelerations at smaller heights. These findings can
  be explained by the Lorentz force, which drives the CME accelerations
  and decreases with height and CME size.

---------------------------------------------------------
Title: Analysis of characteristic parameters of large-scale coronal
    waves observed by STEREO/EUVI
Authors: Muhr, N.; Veronig, A. M.; Kienreich, I. W.; Temmer, M.;
   Vrsnak, B.
2011arXiv1107.0921M    Altcode:
  The kinematical evolution of four EUV waves, well observed by the
  Extreme UltraViolet Imager (EUVI) onboard the Solar-Terrestrial
  Relations Observatory (STEREO), is studied by visually tracking the
  wave fronts as well as by a semiautomatized perturbation profile
  method leading to results matching each other within the error
  limits. The derived mean velocities of the events under study lie
  in the range of 220-350 km/s. The fastest of the events (May 19,
  2007) reveals a significant deceleration of \approx -190 m s-2 while
  the others are consistent with a constant velocity during the wave
  propagation. The evolution of the maximum intensity values reveals
  initial intensification by 20 up to 70%, and decays to original
  levels within 40-60 min, while the width at half maximum and full
  maximum of the perturbation profiles are broadening by a factor of
  2 - 4. The integral below the perturbation profile remains basically
  constant in two cases, while it shows a decrease by a factor of 3 -
  4 in the other two cases. From the peak perturbation amplitudes we
  estimate the corresponding magnetosonic Mach numbers Mms which are
  in the range of 1.08-1.21. The perturbation profiles reveal three
  distinct features behind the propagating wave fronts: coronal dimmings,
  stationary brightenings and rarefaction regions. All of them appear
  after the wave passage and are only slowly fading away. Our findings
  indicate that the events under study are weak shock fast-mode MHD
  waves initiated by the CME lateral expansion.

---------------------------------------------------------
Title: The Drag Based Model of ICME Propagation
Authors: Dumbović, M.; Vršnak, B.; Žic, T.; Vrbanec, D.; Veronig,
   A.; Temmer, M.; Rollett, T.; Moestl, C.; Moon, Y. -J.
2011simi.confR...2D    Altcode:
  One of central issues of space weather is the propagation of
  interplanetary coronal mass ejections (ICMEs). At the heliospheric
  distances beyond R=20 solar radii the "aerodynamic" drag is presumably
  the dominant force governing ICME propagation; therefore, a drag based
  model (DBM) was established, which can be used to forecast the ICME
  arrival at the Earth. <P />First, the model was tested on a sample
  of CMEs by combining remote observations of the CME take-off gained
  by the LASCO onboard SOHO, and in situ measurements from ACE and Wind
  satellites. The results of the DBM were compared to observational data
  and a fairly good agreement of the two was found. The model was then
  tested against STEREO observations. The ICME kinematics was inferred
  from STEREO observations by applying the Harmonic Mean method and
  compared to the DBM results. In this way we were able to reproduce
  the propagation of both slow and fast ICMEs, as well as to identify
  ICME-ICME interactions and a transition from fast-to-slow solar wind
  regimes. Finally, a statistical study was performed, where parameters
  were varied within a model in order to obtain optimal values, for
  which the average difference in the observed and calculated TT is zero
  (O-C=0) and the O-C scatter gets minimum. The source of the scatter
  in O–C values was investigated. <P />The research leading to the
  results presented in this paper has received funding from European
  Community's Seventh Framework Programme (FP7/2007-2013) under grant
  agreement No. 218816.

---------------------------------------------------------
Title: Multiple, distant (40°) in situ observations of a magnetic
    cloud and a corotating interaction region complex
Authors: Farrugia, C. J.; Berdichevsky, D. B.; Möstl, C.; Galvin,
   A. B.; Leitner, M.; Popecki, M. A.; Simunac, K. D. C.; Opitz, A.;
   Lavraud, B.; Ogilvie, K. W.; Veronig, A. M.; Temmer, M.; Luhmann,
   J. G.; Sauvaud, J. A.
2011JASTP..73.1254F    Altcode:
  We report a comprehensive analysis of in situ observations made
  by Wind and the STEREO probes (STA, STB) of a complex interaction
  between a magnetic cloud (MC) and a corotating interaction region (CIR)
  occurring near the heliospheric current sheet (HCS) on November 19-21,
  2007. The probes were separated by 0.7 AU (∼40<SUP>∘</SUP>) with
  a spread in heliographic latitudes (4.8,° 2.2,° and -0.4,° for STB,
  Wind and STA, respectively). We employ data from the MFI, SWE and 3DP
  instruments on Wind, and the PLASTIC and IMPACT suites on STEREO. STB,
  located east of Earth, observed a forward shock followed by signatures
  of a MC. The MC took the role of the HCS in that the polarity of the
  interplanetary magnetic field (IMF) on exit was the reverse of that
  on entry. A passage through a plasma sheet was observed. Along the
  Sun-Earth line Wind observed a stream interface (SI) between a forward
  and a reverse shock. A MC, compressed by the CIR, was entrained in
  this. STA, located 20° to the west of Earth, saw a MC which was not
  preceded by a shock. A SI trailed the transient. The shocks are examined
  using various methods and from this it is concluded that the forward
  shock at Wind—but not at STB—was driven by the MC. Examining the MC
  by Grad-Shafranov reconstruction, we find evidence of a double-flux rope
  structure at Wind and STA and possibly also at STB. The orientations are
  at variance with the notion of a large-scale flux tube being observed at
  the three spacecraft. We find consistency of this with the directional
  properties of the solar wind "strahl" electrons. We examine aspects of
  the geomagnetic response and find a double-dip storm corresponding to
  the two interplanetary triggers. The minimum Dst phase was prolonged
  and the geoeffects were intensified due to the interaction. We conclude
  that while the formation of compound streams is a common feature of
  interplanetary space, understanding their components when CIRs are
  involved is a complicated matter needing numerical simulations and/or
  more in situ observations for its complete elucidation.

---------------------------------------------------------
Title: Equatorial coronal holes, solar wind high-speed streams,
    and their geoeffectiveness
Authors: Verbanac, G.; Vršnak, B.; Veronig, A.; Temmer, M.
2011A&A...526A..20V    Altcode:
  Context. Solar wind high-speed streams (HSSs), originating in equatorial
  coronal holes (CHs), are the main driver of the geomagnetic activity in
  the late-declining phase of the solar cycle. <BR /> Aims: We analyze
  correlations between CH characteristics, HSSs parameters, and the
  geomagnetic activity indices, to establish empirical relationships
  that would provide forecasting of the solar wind characteristics,
  as well as the effect of HSSs on the geomagnetic activity in periods
  when the effect of coronal mass ejections is low. <BR /> Methods:
  We apply the cross-correlation analysis to the fractional CH area
  (CH) measured between central meridian distances ±10°, solar wind
  parameters (flow velocity V, proton density n, temperature T, and
  the magnetic field B), and the geomagnetic indices Dst and Ap. <BR
  /> Results: The cross-correlation analysis reveals a high degree
  of correlation between all studied parameters. In particular, we
  show that the Ap index is considerably more sensitive to HSS and CH
  characteristics than Dst. The Ap and Dst indices are most tightly
  correlated with the solar wind parameter BV<SUP>2</SUP>. <BR />
  Conclusions: From the point of view of space weather, the most
  important result is that the established empirical relationships
  provide a few-days-in-advance forecasting of the HSS characteristics
  and the related geomagnetic activity at the six-hour resolution. <P
  />Appendices, Figs. 9-14, and table 4 are only available in electronic
  form at <A href="http://www.aanda.org">http://www.aanda.org</A>

---------------------------------------------------------
Title: Case Study of Four Homologous Large-scale Coronal Waves
    Observed on 2010 April 28 and 29
Authors: Kienreich, I. W.; Veronig, A. M.; Muhr, N.; Temmer, M.;
   Vršnak, B.; Nitta, N.
2011ApJ...727L..43K    Altcode: 2011arXiv1101.5232K
  On 2010 April 28 and 29, the Solar TErrestrial Relations Observatory
  B/Extreme Ultraviolet Imager observed four homologous large-scale
  coronal waves, the so-called EIT-waves, within 8 hr. All waves emerged
  from the same source active region, were accompanied by weak flares and
  faint coronal mass ejections, and propagated into the same direction
  at constant velocities in the range of ~220-340 km s<SUP>-1</SUP>. The
  last of these four coronal wave events was the strongest and fastest,
  with a velocity of 337 ± 31 km s<SUP>-1</SUP> and a peak perturbation
  amplitude of ~1.24, corresponding to a magnetosonic Mach number of M
  <SUB>ms</SUB> ~ 1.09. The magnetosonic Mach numbers and velocities of
  the four waves are distinctly correlated, suggestive of the nonlinear
  fast-mode magnetosonic wave nature of the events. We also found a
  correlation between the magnetic energy buildup times and the velocity
  and magnetosonic Mach number.

---------------------------------------------------------
Title: Implementation of a Calcium telescope at Kanzelhöhe
    Observatory (KSO)
Authors: Hirtenfellner-Polanec, W.; Temmer, M.; Pötzi, W.; Freislich,
   H.; Veronig, A. M.; Hanslmeier, A.
2011CEAB...35..205H    Altcode:
  A new telescope is implemented at Kanzelhöhe Observatory in order to
  observe the chromosphere in the Ca II K line at 393.4 nm (FWHM 0.3
  nm). The design of the new Ca camera system is very similar to the
  well established Kanzelhöhe Photosphere Digital Camera and the Hα
  system and allows obtaining automatically full disc Ca~II~K 2k×2k
  images time series with a cadence of a few seconds. The main purpose
  of this new instrument is a high precision full disc imaging of the
  chromosphere in order to observe flares, plages and the chromospheric
  network. The Ca emission is also an indicator for magnetic activity
  on the sun. Therefore the Ca data will be taken for analysing the
  variations in the structures of the magnetic field.

---------------------------------------------------------
Title: STEREO and Wind observations of a fast ICME flank triggering
    a prolonged geomagnetic storm on 5-7 April 2010
Authors: Möstl, C.; Temmer, M.; Rollett, T.; Farrugia, C. J.; Liu,
   Y.; Veronig, A. M.; Leitner, M.; Galvin, A. B.; Biernat, H. K.
2010GeoRL..3724103M    Altcode: 2010arXiv1010.4150M
  On 5 April 2010 an interplanetary (IP) shock was detected by the
  Wind spacecraft ahead of Earth, followed by a fast (average speed
  650 km/s) IP coronal mass ejection (ICME). During the subsequent
  moderate geomagnetic storm (minimum D<SUB>st</SUB> = -72 nT,
  maximum K<SUB>p</SUB> = 8<SUP>-</SUP>), communication with the
  Galaxy 15 satellite was lost. We link images from STEREO/ SECCHI to
  the near-Earth in situ observations and show that the ICME did not
  decelerate much between Sun and Earth. The ICME flank was responsible
  for a long storm growth phase. This type of glancing collision was
  for the first time directly observed with the STEREO Heliospheric
  Imagers. The magnetic cloud (MC) inside the ICME cannot be modeled with
  approaches assuming an invariant direction. These observations confirm
  the hypotheses that parts of ICMEs classified as (1) long-duration
  MCs or (2) magnetic-cloud-like (MCL) structures can be a consequence
  of a spacecraft trajectory through the ICME flank.

---------------------------------------------------------
Title: Application of data assimilation to solar wind forecasting
    models
Authors: Innocenti, M.; Lapenta, G.; Vrsnak, B.; Temmer, M.; Veronig,
   A.; Bettarini, L.; Lee, E.; Markidis, S.; Skender, M.; Crespon, F.;
   Skandrani, C.; Soteria Space-Weather Forecast; Data Assimilation Team
2010AGUFMSM54A..08I    Altcode:
  Data Assimilation through Kalman filtering [1,2] is a powerful
  statistical tool which allows to combine modeling and observations
  to increase the degree of knowledge of a given system. We apply this
  technique to the forecast of solar wind parameters (proton speed, proton
  temperature, absolute value of the magnetic field and proton density) at
  1 AU, using the model described in [3] and ACE data as observations. The
  model, which relies on GOES 12 observations of the percentage of the
  meridional slice of the sun covered by coronal holes, grants 1-day and
  6-hours in advance forecasts of the aforementioned quantities in quiet
  times (CMEs are not taken into account) during the declining phase
  of the solar cycle and is tailored for specific time intervals. We
  show that the application of data assimilation generally improves
  the quality of the forecasts during quiet times and, more notably,
  extends the periods of applicability of the model, which can now provide
  reliable forecasts also in presence of CMEs and for periods other than
  the ones it was designed for. Acknowledgement: The research leading
  to these results has received funding from the European Commission’s
  Seventh Framework Programme (FP7/2007-2013) under the grant agreement
  N. 218816 (SOTERIA project: http://www.soteria-space.eu). References:
  [1] R. Kalman, J. Basic Eng. 82, 35 (1960); [2] G. Welch and G. Bishop,
  Technical Report TR 95-041, University of North Carolina, Department
  of Computer Science (2001); [3] B. Vrsnak, M. Temmer, and A. Veronig,
  Solar Phys. 240, 315 (2007).

---------------------------------------------------------
Title: Multiple, Distant (40 deg) in situ Observations of a Magnetic
    Cloud and a Corotating Interaction Region Complex
Authors: Farrugia, C. J.; Berdichevsky, D. B.; Moestl, C.; Galvin,
   A. B.; Leitner, M.; Popecki, M.; Simunac, K. D.; Opitz, A.; Lavraud,
   B.; Ogilvie, K.; Veronig, A.; Temmer, M.; Luhmann, J. G.; Sauvaud, J.
2010AGUFMSH51C1689F    Altcode:
  We report a comprehensive analysis of in situ observations made
  by Wind and the STEREO probes (STA, STB) of a complex interaction
  between a magnetic cloud (MC) and a corotating interaction region (CIR)
  occurring near the heliospheric current sheet (HCS) on November 19-21,
  2007. The probes were separated by 0.7 AU (~40 deg) with a spread in
  heliographic latitudes (4.8, 2.2, and -0.4 deg for STB, Wind and STA,
  respectively). We employ data from the MFI, SWE and 3DP instruments
  on Wind, and the PLASTIC and IMPACT suites on STEREO. STB, located
  east of Earth, observed a forward shock followed by signatures of
  a MC. The MC took the role of the HCS in that the polarity of the
  interplanetary magnetic field (IMF) on exit was the reverse of that on
  entry. A passage through a plasma sheet is observed. Along the Sun-Earth
  line Wind observed a stream interface (SI) between a forward and a
  reverse shock. A MC, compressed by the CIR, was entrained in this. STA,
  located 20 deg to the west of Earth, saw a MC which was not preceded
  by a shock. A SI trailed the transient. The shocks are examined using
  various methods and from this it is concluded that the forward shock
  at Wind - but not at STB - was driven by the MC. Examining the MC by
  Grad-Shafranov reconstruction, we find evidence of a double-flux rope
  structure at Wind and STA and possibly also at STB. The orientations are
  at variance with the notion of a large-scale flux tube being observed at
  the three spacecraft. We find consistency of this with the directional
  properties of the solar wind "strahl" electrons. We examine aspects of
  the geomagnetic response and find a double-dip storm corresponding to
  the two interplanetary triggers. The minimum Dst phase was prolonged
  and the geoffects were intensified due to the interaction. We conclude
  that while the formation of compound streams is a common feature of
  interplanetary space, understanding their components when CIRs are
  involved is a complicated matter needing numerical simulations and/or
  morein situ observations for its complete elucidation.

---------------------------------------------------------
Title: Propagation Directions and Kinematics of STEREO CME/ICMEs
    Events
Authors: Rollett, T.; Moestl, C.; Temmer, M.; Veronig, A.; Lugaz,
   N.; Biernat, H. K.
2010AGUFMSH41A1775R    Altcode:
  The Heliospheric Imagers on board the two STEREO twin satellites give
  us the possibilities to track Coronal Mass Ejections up to a distance
  of 1 AU. For events of our interest, remote sensing data as well as
  in situ measurements from the other STEREO spacecraft or Wind are
  available. The combination of both allows us to calculate a constant
  propagation direction in the ecliptic plane by using different methods
  (Fixed-Phi and the Harmonic Mean). These methods convert the measured
  elongation into distance by making different assumptions on the
  shape of the CME. With the combined data sets we can also derive the
  kinematics (distance-velocity plots) and try to crosscheck the results
  by taking care of the ambient solar wind. Moreover, we use inverse
  fitting methods for both the Fixed-Phi and Harmonic Mean approaches
  (which assume constant velocity) to fit our measurements and compare
  it to the results calculated by our combined method.

---------------------------------------------------------
Title: The CME/ICME relationship for the 3-5 April 2010 and Aug 1-4
    2010 events
Authors: Moestl, C.; Temmer, M.; Rollett, T.; Kilpua, E. K.; Farrugia,
   C. J.; Veronig, A.; Galvin, A. B.; Biernat, H. K.
2010AGUFMSH43C..07M    Altcode:
  For two coronal mass ejections (CMEs) associated with interplanetary
  CMEs (ICMEs) causing moderate geomagnetic storms in 2010, we discuss
  properties such as interplanetary propagation, orientation and
  arrival time calculation. We study heliospheric images of the CMEs
  provided by STEREO / HI in combination with in situ observations by
  the Wind spacecraft near Earth. The 3-5 April 2010 event was the
  first fast (800 km/s) ICME including a magnetic cloud observed by
  both the STEREO/HI instruments and a near Earth spacecraft. During
  the subsequent geomagnetic storm (minimum Dst = -72 nT, maximum Kp =
  8-), communication with the Galaxy 15 satellite was lost. Using forward
  modeling in combination with HI techniques and the in situ velocity, we
  show that the ICME did not decelerate much between Sun and Earth. Earth
  was not hit directly, but the ICME flank was responsible for a long
  storm growth phase. The magnetic cloud (MC) inside the ICME cannot
  be modeled with approaches assuming an invariant direction. These
  observations confirm the hypotheses that parts of ICMEs classified as
  (1) long-duration MCs or (2) magnetic-cloud-like (MCL) structures
  can be a consequence of a spacecraft trajectory through the ICME
  flank. The 1-4 Aug 2010 events consisted of several CMEs accompanied
  by multiple ICME signatures near Earth, responsible for a two-step
  geomagnetic storm. We discuss which of the ICMEs correspond to the
  flare/filaments/CMEs observed by STEREO/COR/HI and SDO HMI/AIA observed
  closer to the Sun. We apply reconstruction methods to estimate the
  local flux rope orientation and other properties. The ICME signatures
  are linked to HI observations of the CME fronts, which yields full
  CME kinematics between the Sun and Earth. STEREO Ahead HI1/2 images
  of the 3-5 April 2010 Earth-directed coronal mass ejection.

---------------------------------------------------------
Title: On the Origin of the Solar Moreton Wave of 2006 December 6
Authors: Balasubramaniam, K. S.; Cliver, E. W.; Pevtsov, A.; Temmer,
   M.; Henry, T. W.; Hudson, H. S.; Imada, S.; Ling, A. G.; Moore, R. L.;
   Muhr, N.; Neidig, D. F.; Petrie, G. J. D.; Veronig, A. M.; Vršnak,
   B.; White, S. M.
2010ApJ...723..587B    Altcode:
  We analyzed ground- and space-based observations of the eruptive flare
  (3B/X6.5) and associated Moreton wave (~850 km s<SUP>-1</SUP> ~270°
  azimuthal span) of 2006 December 6 to determine the wave driver—either
  flare pressure pulse (blast) or coronal mass ejection (CME). Kinematic
  analysis favors a CME driver of the wave, despite key gaps in coronal
  data. The CME scenario has a less constrained/smoother velocity versus
  time profile than is the case for the flare hypothesis and requires an
  acceleration rate more in accord with observations. The CME picture is
  based, in part, on the assumption that a strong and impulsive magnetic
  field change observed by a GONG magnetograph during the rapid rise phase
  of the flare corresponds to the main acceleration phase of the CME. The
  Moreton wave evolution tracks the inferred eruption of an extended
  coronal arcade, overlying a region of weak magnetic field to the west
  of the principal flare in NOAA active region 10930. Observations of
  Hα foot point brightenings, disturbance contours in off-band Hα
  images, and He I 10830 Å flare ribbons trace the eruption from 18:42
  to 18:44 UT as it progressed southwest along the arcade. Hinode EIS
  observations show strong blueshifts at foot points of this arcade
  during the post-eruption phase, indicating mass outflow. At 18:45
  UT, the Moreton wave exhibited two separate arcs (one off each flank
  of the tip of the arcade) that merged and coalesced by 18:47 UT to
  form a single smooth wave front, having its maximum amplitude in
  the southwest direction. We suggest that the erupting arcade (i.e.,
  CME) expanded laterally to drive a coronal shock responsible for the
  Moreton wave. We attribute a darkening in Hα from a region underlying
  the arcade to absorption by faint unresolved post-eruption loops.

---------------------------------------------------------
Title: Multiwavelength Imaging and Spectroscopy of Chromospheric
    Evaporation in an M-class Solar Flare
Authors: Veronig, A. M.; Rybák, J.; Gömöry, P.; Berkebile-Stoiser,
   S.; Temmer, M.; Otruba, W.; Vršnak, B.; Pötzi, W.; Baumgartner, D.
2010ApJ...719..655V    Altcode: 2010arXiv1007.0930V
  We study spectroscopic observations of chromospheric evaporation mass
  flows in comparison with the energy input by electron beams derived
  from hard X-ray (HXR) data for the white-light M2.5 flare of 2006 July
  6. The event was captured in high-cadence spectroscopic observing mode
  by SOHO/CDS combined with high-cadence imaging at various wavelengths
  in the visible, extreme ultraviolet, and X-ray domain during the joint
  observing campaign JOP171. During the flare peak, we observe downflows
  in the He I and O V lines formed in the chromosphere and transition
  region, respectively, and simultaneous upflows in the hot coronal
  Si XII line. The energy deposition rate by electron beams derived
  from RHESSI HXR observations is suggestive of explosive chromospheric
  evaporation, consistent with the observed plasma motions. However, for
  a later distinct X-ray burst, where the site of the strongest energy
  deposition is exactly located on the Coronal Diagnostics Spectrometer
  (CDS) slit, the situation is intriguing. The O V transition region
  line spectra show the evolution of double components, indicative of
  the superposition of a stationary plasma volume and upflowing plasma
  elements with high velocities (up to 280 km s<SUP>-1</SUP>) in single
  CDS pixels on the flare ribbon. However, the energy input by electrons
  during this period is too small to drive explosive chromospheric
  evaporation. These unexpected findings indicate that the flaring
  transition region is much more dynamic, complex, and fine structured
  than is captured in single-loop hydrodynamic simulations.

---------------------------------------------------------
Title: Statistical Properties of Flares and Sunspots over the
    Solar Cycle
Authors: Temmer, M.
2010ASPC..428..161T    Altcode: 2010arXiv1002.0413T
  The present paper reviews results derived from statistical studies of
  solar activity indices. The prolonged minimum phase of cycle 23 raised
  the question of peculiarities inherent in cycle 23. The most important
  solar activity index is the relative sunspot number and though most
  of the other indices are closely related, shifts are obtained between
  their peak activities of the order of 1-2 years. These shifts reveal
  a 22-year pattern which can be attributed to solar interior or dynamo
  related processes. The minimum phase of cycle 23 is not found to be
  exceptional. Investigating the relative sunspot numbers over the past
  150 years, solar cycles of more prolonged minima are observed. Since
  1920, solar activity has been quite high ("modern maximum") and cycle
  23 might be the herald of the end of this phase.

---------------------------------------------------------
Title: First Observations of a Dome-shaped Large-scale Coronal
    Extreme-ultraviolet Wave
Authors: Veronig, A. M.; Muhr, N.; Kienreich, I. W.; Temmer, M.;
   Vršnak, B.
2010ApJ...716L..57V    Altcode: 2010arXiv1005.2060V
  We present first observations of a dome-shaped large-scale
  extreme-ultraviolet coronal wave, recorded by the Extreme Ultraviolet
  Imager instrument on board STEREO-B on 2010 January 17. The main
  arguments that the observed structure is the wave dome (and not the
  coronal mass ejection, CME) are (1) the spherical form and sharpness of
  the dome's outer edge and the erupting CME loops observed inside the
  dome; (2) the low-coronal wave signatures above the limb perfectly
  connecting to the on-disk signatures of the wave; (3) the lateral
  extent of the expanding dome which is much larger than that of the
  coronal dimming; and (4) the associated high-frequency type II burst
  indicating shock formation low in the corona. The velocity of the upward
  expansion of the wave dome (v ~ 650 km s<SUP>-1</SUP>) is larger than
  that of the lateral expansion of the wave (v ~ 280 km s<SUP>-1</SUP>),
  indicating that the upward dome expansion is driven all the time,
  and thus depends on the CME speed, whereas in the lateral direction it
  is freely propagating after the CME lateral expansion stops. We also
  examine the evolution of the perturbation characteristics: first the
  perturbation profile steepens and the amplitude increases. Thereafter,
  the amplitude decreases with r <SUP>-2.5 ± 0.3</SUP>, the width
  broadens, and the integral below the perturbation remains constant. Our
  findings are consistent with the spherical expansion and decay of a
  weakly shocked fast-mode MHD wave.

---------------------------------------------------------
Title: Four decades of geomagnetic and solar activity: 1960-2001
Authors: Verbanac, Giuli; Vršnak, Bojan; Temmer, Manuela; Mandea,
   Mioara; Korte, Monika
2010JASTP..72..607V    Altcode:
  We analyze the relationship between some space weather indices (Dst,
  Ap, F10.7) and geomagnetic effects on the regional (European) scale,
  over the period 1960-2001. The remaining external field signal (RES)
  detected in the Northward magnetic component of the European observatory
  annual means are used as an indicator of the regional geomagnetic
  activity. Relationship RES-F10.7 suggests correction factors for getting
  the geomagnetic annual means of the Northern component less affected by
  the external sources. We have found some time lags among investigated
  parameters. These delays may suggest that the Ap responds to the solar
  activity in a differently than Dst and RES, Ap being more sensitive
  to the high-speed streams (HSS) and the Alfvenic waves present in HSS,
  while Dst and RES being more influenced by the coronal mass ejections
  activity (CME).

---------------------------------------------------------
Title: Calculating the propagation direction of coronal mass ejections
    by connecting in situ observations with heliospheric images
Authors: Rollett, Tanja; Möstl, Christian; Temmer, Manuela; Veronig,
   Astrid; Biernat, Helfried K.
2010EGUGA..12.3468R    Altcode:
  We determined the propagation direction of two coronal mass ejections
  by using data provided by the Heliospheric Imagers (HI) and the PLASTIC
  and IMPACT instruments onboard the two STEREO satellites. To facilitate
  the tracking of the CME's leading edge we made time-elongation plots
  (J-plots) for the investigated events and tracked the apparent leading
  edge therein several times in order to estimate the measurement
  error. For converting elongation to distance we compared several
  methods (Point-P, Fixed-Phi and their harmonic mean). To determine the
  direction of the CME's propagation in the ecliptic we connected the
  CME-track derived from HI J-plots with the measured in situ arrival
  time by modifying the propagation direction within the used model
  equations. The resulting directions and their errors are discussed
  with respect to the different assumptions used for each technique.

---------------------------------------------------------
Title: Combined STEREO/RHESSI Study of Coronal Mass Ejection
    Acceleration and Particle Acceleration in Solar Flares
Authors: Temmer, M.; Veronig, A. M.; Kontar, E. P.; Krucker, S.;
   Vršnak, B.
2010ApJ...712.1410T    Altcode: 2010arXiv1002.3080T
  Using the potential of two unprecedented missions, Solar Terrestrial
  Relations Observatory (STEREO) and Reuven Ramaty High-Energy Solar
  Spectroscopic Imager (RHESSI), we study three well-observed fast coronal
  mass ejections (CMEs) that occurred close to the limb together with
  their associated high-energy flare emissions in terms of RHESSI hard
  X-ray (HXR) spectra and flux evolution. From STEREO/EUVI and STEREO/COR1
  data, the full CME kinematics of the impulsive acceleration phase up to
  ~4 R <SUB>sun</SUB> is measured with a high time cadence of &lt;=2.5
  minutes. For deriving CME velocity and acceleration, we apply and
  test a new algorithm based on regularization methods. The CME maximum
  acceleration is achieved at heights h &lt;= 0.4 R <SUB>sun</SUB>,
  and the peak velocity at h &lt;= 2.1 R <SUB>sun</SUB> (in one case,
  as small as 0.5 R <SUB>sun</SUB>). We find that the CME acceleration
  profile and the flare energy release as evidenced in the RHESSI HXR flux
  evolve in a synchronized manner. These results support the "standard"
  flare/CME model which is characterized by a feedback relationship
  between the large-scale CME acceleration process and the energy release
  in the associated flare.

---------------------------------------------------------
Title: STEREO quadrature observations of the large-scale EUV wave
    of Feb 13th, 2009
Authors: Ines Kienreich, Mag.; Veronig, Astrid; Temmer, Manuela
2010cosp...38.1841I    Altcode: 2010cosp.meet.1841I
  The event on Feb 13th, 2009 was the first case of a global coronal
  wave observed by the STEREO twin satellites in quadrature. The wave's
  initiation site was at the disk center in EUVI STEREO-B and precisely at
  the limb in STEREO-A. Therefore it was possible to determine the wave's
  on-disk as well as edge-on kinematics and to study its three-dimensional
  structure. From the two STEREO observations we derive the height of
  propagation of the wave, which was found to be in the range between
  80-100 Mm above the photosphere. Comparison of the early phases of
  the contemporaneous CME and the wave's kinematics suggest that the
  wave is set off by the CME lateral expansion. The wave propagates
  globally over the whole hemisphere with a constant velocity 263 16 km
  s-1, which is close to the fast magnetosonic speed in the quiet solar
  corona. Thus we conclude that the observed EUV wave is consistent with
  a MHD fast-mode wave.

---------------------------------------------------------
Title: Analysis of a Global Moreton Wave Observed on 2003 October 28
Authors: Muhr, N.; Vršnak, B.; Temmer, M.; Veronig, A. M.;
   Magdalenić, J.
2010ApJ...708.1639M    Altcode: 2009arXiv0911.4405M
  We study the well-pronounced Moreton wave that occurred in association
  with the X17.2 flare/CME event of 2003 October 28. This Moreton wave is
  striking for its global propagation and two separate wave centers, which
  implies that two waves were launched simultaneously. The mean velocity
  of the Moreton wave, tracked within different sectors of propagation
  direction, lies in the range of v ≈ 900-1100 km s<SUP>-1</SUP> with
  two sectors showing wave deceleration. The perturbation profile analysis
  of the wave indicates amplitude growth followed by amplitude weakening
  and broadening of the perturbation profile, which is consistent with
  a disturbance first driven and then evolving into a freely propagating
  wave. The Extreme-Ultraviolet Imaging Telescope wave front is found to
  lie on the same kinematical curve as the Moreton wave fronts indicating
  that both are different signatures of the same physical process. Bipolar
  coronal dimmings are observed on the same opposite east-west edges of
  the active region as the Moreton wave ignition centers. The radio type
  II source, which is cospatially located with the first wave front,
  indicates that the wave was launched from an extended source region
  (gsim60 Mm). These findings suggest that the Moreton wave is initiated
  by the coronal mass ejection expanding flanks.

---------------------------------------------------------
Title: Automated detection of coronal hole areas
Authors: Rotter, Mag. Thomas; Veronig, Astrid; Temmer, Manuela
2010cosp...38.1890R    Altcode: 2010cosp.meet.1890R
  Coronal holes, as regions of low-density plasma on the sun, have
  magnetic fields that open freely into interplanetary space and thus
  shape our heliosphere. Along these open magnetic fields, charged
  particles leave the Sun to form the high speed component of the solar
  wind. SOHO EIT (Extreme ultraviolet Imaging Telescope) provides for the
  first time continuous observations of coronal holes over a full solar
  cycle (no.23). These data enable us to study the solar cycle evolution
  of coronal holes and their relation to in-situ solar wind magnetic
  field and plasma parameters at 1 AU. In the poster we will present
  first results of an automated coronal hole detection algorithm that
  is currently under development. The algorithm uses a histogram-based
  intensity treshholding technique to determine coronal hole areas and
  their positions.

---------------------------------------------------------
Title: Calculation of CME kinematics and propagation directions by
    connecting STEREO HI-images with in situ data
Authors: Rollett, Tanja; Moestl, Christian; Temmer, Manuela; Veronig,
   Astrid; Biernat, Helfried K.
2010cosp...38.1894R    Altcode: 2010cosp.meet.1894R
  On a sample of selected events we determined the propagation directions
  and the kinematics of several coronal mass ejections by using data
  provided by the Heliospheric Imagers (HI) and the PLASTIC and IMPACT
  instruments onboard the two STEREO satellites and the Wind spacecraft
  near Earth. We tracked for each CME the leading edge and core within
  time-elongation plots (Jplots) and converted the measured elongation
  angle into distance by using different methods (Point-P, Fixed-Phi
  and their harmonic mean). Furthermore, we used the Sheeley-method to
  fit our measurements and calculate the propagation angles and arrival
  times at the other spacecraft assuming that the CMEs propagate with
  constant velocity. Finally we discuss our results by comparing the
  kinematics derived from the different techniques.

---------------------------------------------------------
Title: Evolution of solar wind energy densities during solar minimum
    2007-2009, and features of its effects on the Earth's magnetopause
    and magnetosheath
Authors: Farrugia, Charles; Harris, B.; Leitner, Mag. Martin; Moestl,
   Christian; Simunac, Kristin; Galvin, Antoinette; Veronig, Astrid;
   Temmer, Manuela; Luhmann, Janet G.; Szabo, Adam; Biernat, Helfried K.;
   Lucek, Elizabeth A.
2010cosp...38.1898F    Altcode: 2010cosp.meet.1898F
  We quantify the distribution of magnetic and kinetic energies densities
  of the solar wind at 1 AU as the deep solar activity minimum 2007-2009
  progressed. For this we use near -Earth spacecraft Wind and the STEREO-A
  and B probes, the latter giving us a more comprehensive description
  by extending the longitudinal coverage. We relate general trends in
  interplanetary data to observations on the Sun. We then pick out a
  4-month period, characterized by minima in both the kinetic and magnetic
  energy densities, and examine the profiles of the plasma and magnetic
  field parameters. They show slow-slower solar wind interactions with
  pronounced compressions, and low field strengths in slow solar wind
  streams. These are compared with the general plasma and field properties
  of the slow solar wind and differences are noted. Using Cluster data,
  we determine the average shapes of the bow shock and magnetopause for
  this period. We compare these with gas dynamic and MHD predictions for
  the average Alfven Mach number realized. Major features of observations
  in the Earth's magnetosheath are discussed. This work is meant as a
  contribution to Sun-Earth connection studies.

---------------------------------------------------------
Title: Relation between the dynamics of coronal mass ejections and
    solar flare energetics derived from STEREO and RHESSI observations
Authors: Bein, Bianca; Veronig, Astrid; Berkebile-Stoiser, Sigrid;
   Temmer, Manuela
2010cosp...38.3019B    Altcode: 2010cosp.meet.3019B
  We aim to explore the relation of the energy release in solar flares
  to the dynamical evolution of their associated coronal mass ejections
  for a statistically representative sample of events. For our study,
  we use EUV (171˚, 195˚) and white light coronographic observations
  from A A the STEREO (Solar Terrestial Relations Observatory) SECCHI
  instrument suite. Due to the high time cadence of the STEREO EUVI
  and COR images, the detailed CME kinematics from the initiation
  through the impulsive acceleration to the propagation phase can
  be derived. Information on the energy release in the flares under
  study comes from hard X-ray observations of the RHESSI instrument
  (Ramaty High Energy Solar Spectroscopic Imager). RHESSI non-thermal
  lightcurves as well as the derivative of the GOES soft X-ray flux are
  compared with the acceleration curve of the associated CME.

---------------------------------------------------------
Title: Coronal mass ejections in the STEREO era
Authors: Temmer, Manuela
2010cosp...38.2967T    Altcode: 2010cosp.meet.2967T
  The present paper reviews recent results derived from studies of
  coronal mass ejections (CMEs) and associated flares. CMEs are the most
  violent activity signatures from our Sun. Discov-ered in the 70's,
  extensive studies were carried out particularly in the SOHO era, but
  still, our understanding of the physical characteristics of CMEs is
  limited. Mainly this is due to single coronagraph observations, which
  image CMEs in projection against the plane of sky, hence, missing their
  3D structure and evolution. The Solar Terrestrial Relations Observatory
  -STEREO, launched on October 25th, 2006, is composed of two nearly
  identical spacecrafts, one ahead of Earth in its orbit (STEREO-A), the
  other trailing behind (STEREO-B). This unprecedented mission observes
  CMEs simultaneously from two different vantage points, from which new
  insights into the 3D aspects of CMEs are derived. In addition, with the
  Heliospheric Imager instruments aboard STEREO, events can be tracked
  seamlessly from Sun to Earth where they can be related to in-situ plasma
  and magnetic field measurements. High spatial and temporal resolution
  images of the low corona in EUV and from coronagraphs in white light
  give information on CME initiation and its early propagation phase. In
  com-bination with observations of the associated flare, those enable us
  to examine in detail the CME-flare relationship, from both observational
  and theoretical points of view. Recent studies give evidence that the
  energy release process in flares (HXR emission) and the acceleration of
  CMEs are closely related. Complementary multi-wavelength observations
  of eruptive events are therefore needed to understand the "big picture"
  including both phenomena CMEs and flares.

---------------------------------------------------------
Title: Study of the kinematics and driver of the global Moreton wave
    observed on 2003 October 28
Authors: Muhr, Mmag. Nicole; Vrsnak, Bojan; Temmer, Manuela; Veronig,
   Astrid; Magdalenic, Jasmina
2010cosp...38.1844M    Altcode: 2010cosp.meet.1844M
  We analyze the evolution and kinematics of the fast, globally
  propagating Moreton wave of 2003 October 28 associated with the extreme
  X17.2 solar flare/CME event. This Moreton wave is distinct due to its
  strengths and azimuthal span of span 360. We study the wave kinematics
  in different propagation directions, and compare it with the following
  associated phenomena: EIT wave, coronal dimmings, fast halo CME, flare,
  and type II burst. The sectoral analysis yield mean velocity values
  in the range 900-1000 km/s; two sectors show wave deceleration. The
  perturbation profile evolution indicates an amplitude growth followed
  by amplitude weakening and broadening, which is consistent with a
  disturbance first driven and then evolving into a freely propagating
  wave. We find two `'radiant points" for the Moreton wave fronts on
  opposite east-west edges of the source region, roughly co-spatial with
  the bipolar coronal dimming. The co-spatiality of the associated radio
  type II burst source and the first Moreton wave fronts indicate that
  the wave was launched from an extended region. These findings indicate
  that the wave is initiated by the CME expanding flanks.

---------------------------------------------------------
Title: Direction and orientation of CME/ICME events observed by STEREO
Authors: Moestl, Christian; Rollett, Tanja; Temmer, Manuela; Farrugia,
   Charles; Veronig, Astrid; Galvin, Antoinette; Biernat, Helfried K.
2010cosp...38.1881M    Altcode: 2010cosp.meet.1881M
  The two NASA STEREO spacecraft are now approaching a quadrature
  configuration with respect to the Earth. In conjunction with the rising
  solar activity this represents a great opportunity to study coronal
  mass ejections (CMEs) during their journey from the Sun to 1 AU. We
  are in particular concerned with those events which were observed by
  the STEREO/SECCHI imaging instrument in the inner heliosphere and which
  were also detected in situ at 1 AU with STEREO (IMPACT/PLASTIC) or WIND
  (SWE/MFI). This allows for example to check (1) if the direction of
  propagation given by various direction-finding techniques is indeed
  correlated with the signatures which are later observed in situ and (2)
  if the orientation of the magnetic flux rope inside the ICME, which we
  model using the Grad-Shafranov technique, is reflected in properties of
  the CME. Also, the classic three-part structure of CMEs can be related
  to the in situ data. The results are discussed regarding the possibility
  to forecast ICME properties from observations closer to the Sun.

---------------------------------------------------------
Title: On the 3-D reconstruction of Coronal Mass Ejections using
    coronagraph data
Authors: Mierla, M.; Inhester, B.; Antunes, A.; Boursier, Y.; Byrne,
   J. P.; Colaninno, R.; Davila, J.; de Koning, C. A.; Gallagher, P. T.;
   Gissot, S.; Howard, R. A.; Howard, T. A.; Kramar, M.; Lamy, P.;
   Liewer, P. C.; Maloney, S.; Marqué, C.; McAteer, R. T. J.; Moran, T.;
   Rodriguez, L.; Srivastava, N.; St. Cyr, O. C.; Stenborg, G.; Temmer,
   M.; Thernisien, A.; Vourlidas, A.; West, M. J.; Wood, B. E.; Zhukov,
   A. N.
2010AnGeo..28..203M    Altcode:
  Coronal Mass ejections (CMEs) are enormous eruptions of magnetized
  plasma expelled from the Sun into the interplanetary space, over the
  course of hours to days. They can create major disturbances in the
  interplanetary medium and trigger severe magnetic storms when they
  collide with the Earth's magnetosphere. It is important to know their
  real speed, propagation direction and 3-D configuration in order to
  accurately predict their arrival time at the Earth. Using data from
  the SECCHI coronagraphs onboard the STEREO mission, which was launched
  in October 2006, we can infer the propagation direction and the 3-D
  structure of such events. In this review, we first describe different
  techniques that were used to model the 3-D configuration of CMEs in
  the coronagraph field of view (up to 15 R⊙). Then, we apply these
  techniques to different CMEs observed by various coronagraphs. A
  comparison of results obtained from the application of different
  reconstruction algorithms is presented and discussed.

---------------------------------------------------------
Title: Linking remote imagery of two coronal mass ejections to their
    in situ signatures at 1 AU
Authors: Moestl, C.; Farrugia, C. J.; Temmer, M.; Miklenic, C.;
   Veronig, A.; Galvin, A. B.; Leitner, M.; Biernat, H. K.
2009AGUFMSH41A1629M    Altcode:
  We report on how the internal structure of two coronal mass ejections
  at 1 AU might be deduced from white-light images of the heliosphere
  taken from a remote observation point. On June 6-7 2008 the STEREO-B
  spacecraft encountered typical signatures of a magnetic flux rope inside
  an interplanetary coronal mass ejection (ICME). Its axis was inclined
  at 45° to the solar equatorial plane, crossing it at approximately
  30° east of Earth. This direction matches well with various CME
  direction-finding techniques to within 15°, and a possible westward
  deflection of 10° took place between the Sun and 1 AU. Further, we use
  remote images from STEREO-A to show that (1) the CME is unambiguously
  connected to the ICME which swept over STEREO B and can be tracked all
  the way to the 1 AU event, (2) the particular arc-like morphology of the
  CME pointing to an inclined axis, and (3) the three-part structure of
  the CME may be plausibly related to the in situ data with clear density
  variations. The CME event on Feb 13 2009 followed by a magnetic cloud
  on Feb 18 2009 is discussed from the same viewpoint, though the in-situ
  signatures are more complex than for the simple event discussed above.

---------------------------------------------------------
Title: Linking Remote Imagery of a Coronal Mass Ejection to Its In
    Situ Signatures at 1 AU
Authors: Möstl, C.; Farrugia, C. J.; Temmer, M.; Miklenic, C.;
   Veronig, A. M.; Galvin, A. B.; Leitner, M.; Biernat, H. K.
2009ApJ...705L.180M    Altcode: 2009arXiv0910.1188M
  In a case study (2008 June 6-7) we report on how the internal structure
  of a coronal mass ejection (CME) at 1 AU can be anticipated from
  remote observations of white-light images of the heliosphere. Favorable
  circumstances are the absence of fast equatorial solar wind streams and
  a low CME velocity which allow us to relate the imaging and in situ
  data in a straightforward way. The STEREO-B spacecraft encountered
  typical signatures of a magnetic flux rope inside an interplanetary
  CME (ICME) whose axis was inclined at 45° to the solar equatorial
  plane. Various CME direction-finding techniques yield consistent
  results to within 15°. Further, remote images from STEREO-A show that
  (1) the CME is unambiguously connected to the ICME and can be tracked
  all the way to 1 AU, (2) the particular arc-like morphology of the CME
  points to an inclined axis, and (3) the three-part structure of the CME
  may be plausibly related to the in situ data. This is a first step in
  predicting both the direction of travel and the internal structure of
  CMEs from complete remote observations between the Sun and 1 AU, which
  is one of the main requirements for forecasting the geo-effectiveness
  of CMEs.

---------------------------------------------------------
Title: STEREO Quadrature Observations of the Three-Dimensional
    Structure and Driver of a Global Coronal Wave
Authors: Kienreich, I. W.; Temmer, M.; Veronig, A. M.
2009ApJ...703L.118K    Altcode: 2009arXiv0908.3571K
  We present the first observations of a global coronal wave ("EIT wave")
  from the two STEREO satellites in quadrature. The wave's initiation
  site was at the disk center in STEREO-B and precisely on the limb in
  STEREO-A. These unprecedented observations from the STEREO Extreme
  Ultraviolet Imaging (EUVI) instruments enable us to gain insight into
  the wave's kinematics, initiation, and three-dimensional structure. The
  wave propagates globally over the whole solar hemisphere visible to
  STEREO-B with a constant velocity of ~263 ± 16 km s<SUP>-1</SUP>. From
  the two STEREO observations, we derive a height of the wave in the
  range of ~80-100 Mm. Comparison of the wave kinematics with the early
  phase of the erupting coronal mass ejection (CME) structure indicates
  that the wave is initiated by the CME lateral expansion, and then
  propagates freely with a velocity close to the fast magnetosonic speed
  in the quiet solar corona.

---------------------------------------------------------
Title: Analytic Modeling of the Moreton Wave Kinematics
Authors: Temmer, M.; Vršnak, B.; Žic, T.; Veronig, A. M.
2009ApJ...702.1343T    Altcode: 2009arXiv0908.3746T
  The issue whether Moreton waves are flare-ignited or coronal mass
  ejection (CME)-driven, or a combination of both, is still a matter of
  debate. We develop an analytical model describing the evolution of a
  large-amplitude coronal wave emitted by the expansion of a circular
  source surface in order to mimic the evolution of a Moreton wave. The
  model results are confronted with observations of a strong Moreton
  wave observed in association with the X3.8/3B flare/CME event from
  2005 January 17. Using different input parameters for the expansion
  of the source region, either derived from the real CME observations
  (assuming that the upward moving CME drives the wave), or synthetically
  generated scenarios (expanding flare region, lateral expansion of the
  CME flanks), we calculate the kinematics of the associated Moreton
  wave signature. Those model input parameters are determined which
  fit the observed Moreton wave kinematics best. Using the measured
  kinematics of the upward moving CME as the model input, we are not able
  to reproduce the observed Moreton wave kinematics. The observations
  of the Moreton wave can be reproduced only by applying a strong and
  impulsive acceleration for the source region expansion acting in a
  piston mechanism scenario. Based on these results we propose that the
  expansion of the flaring region or the lateral expansion of the CME
  flanks is more likely the driver of the Moreton wave than the upward
  moving CME front.

---------------------------------------------------------
Title: CME Projection Effects Studied with STEREO/COR and SOHO/LASCO
Authors: Temmer, M.; Preiss, S.; Veronig, A. M.
2009SoPh..256..183T    Altcode:
  Based on a set of 11 CME events we study the impact of projection
  effects by tracking CME leading edge features in the plane of sky
  (traditional CME tracking) from combined STEREO-SECCHI and SOHO-LASCO
  observations up to 20R<SUB>⊙</SUB>. By using CME observations from two
  vantage points and applying triangulation techniques, the source region
  location of the CME on the solar surface was determined (heliospheric
  longitude and latitude) to correct for projection effects. With
  this information, the directivity and "true" speed of a CME can be
  estimated in a simple way. The comparison of the results obtained from
  the spacecraft pairs SOHO-LASCO/STEREO-A and SOHO-LASCO/STEREO-B allows
  us to study the reliability of the method. The determined CME source
  region is generally coincident within ≲10°.

---------------------------------------------------------
Title: Multispacecraft recovery of a magnetic cloud and its origin
    from magnetic reconnection on the Sun
Authors: Möstl, C.; Farrugia, C. J.; Miklenic, C.; Temmer, M.;
   Galvin, A. B.; Luhmann, J. G.; Kilpua, E. K. J.; Leitner, M.;
   Nieves-Chinchilla, T.; Veronig, A.; Biernat, H. K.
2009JGRA..114.4102M    Altcode: 2009JGRA..11404102M
  Multipoint spacecraft observations of a magnetic cloud on 22 May 2007
  have given us the opportunity to apply a multispacecraft technique
  to infer the structure of this large-scale magnetic flux rope in
  the solar wind. Combining WIND and STEREO-B magnetic field and
  plasma measurements, we construct a combined magnetic field map by
  integrating the Grad-Shafranov equation, this being one of the very
  first applications of this technique in the interplanetary context. From
  this we obtain robust results on the shape of the cross section,
  the orientation and magnetic fluxes of the cloud. The only slightly
  “flattened” shape is discussed with respect to its heliospheric
  environment and theoretical expectations. We also relate these results
  to observations of the solar source region and its associated two-ribbon
  flare on 19 May 2007, using Hα images from the Kanzelhöhe observatory,
  SOHO/MDI magnetograms and SECCHI/EUVI 171 Å images. We find a close
  correspondence between the magnetic flux reconnected in the flare and
  the poloidal flux of the magnetic cloud. The axial flux of the cloud
  agrees with the prediction of a recent 3-D finite sheared arcade
  model to within a factor of 2, which is evidence for formation of
  at least half of the magnetic flux of the ejected flux rope during
  the eruption. We outline the relevance of this result to models of
  coronal mass ejection initiation, and find that to explain the solar
  and interplanetary observations elements from sheared arcade as well
  as erupting-flux-rope models are needed.

---------------------------------------------------------
Title: Multi-spacecraft STEREO observations of magnetic clouds
Authors: Möstl, C.; Farrugia, C. J.; Miklenic, C.; Temmer, M.;
   Veronig, A.; Biernat, H. K.; Kilpua, E. K. J.; Galvin, A. B.; Luhmann,
   J. G.; Ogilvie, K. W.
2009EGUGA..11.4987M    Altcode:
  In addition to 3D imaging capabilities, the two STEREO spacecraft
  also provide unprecedented in-situ observations of the local solar
  wind plasma and magnetic field at 1 AU at increasing longitudinal
  separation from Earth. This presents a very good opportunity to
  model interplanetary coronal mass ejections with a clearly rotating
  magnetic field (magnetic clouds) using more than one spacecraft
  to probe their full spatial extent and flux content. This is
  important not only for space weather prediction purposes but also
  for understanding CME initiation processes. To this end, we employ
  the Grad-Shafranov reconstruction technique suitably extended for
  the use of multi-spacecraft data. We present a summary of results on
  some magnetic clouds seen by STEREO and WIND where this approach was
  feasible. Furthermore, we search for the solar sources of these events
  and, wherever possible, also discuss comparisons with CME triangulation
  techniques.

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Title: Cosmic ray modulation by corotating interaction regions
Authors: Čalogović, Jaša; Vršnak, Bojan; Temmer, Manuela; Veronig,
   Astrid M.
2009IAUS..257..425C    Altcode:
  We analyzed the relationship between the ground-based modulation of
  cosmic rays (CR) and corotating interaction regions (CIRs). Daily
  averaged data from 8 different neutron monitor (NM) stations were
  used, covering rigidities from R<SUB>c</SUB> = 0 - 12.91 GeV. The in
  situ solar wind data were taken from the Advanced Composition Explorer
  (ACE) database, whereas the coronal hole (CH) areas were derived from
  the Solar X-Ray Imager onboard GOES-12. For the analysis we have
  chosen a period in the declining phase of solar cycle 23, covering
  the period 25 January-5 May 2005. During the CIR periods CR decreased
  typically from 0.5% to 2%. A cross-correlation analysis showed a
  distinct anti-correlation between the magnetic field and CR, with the
  correlation coefficient (r) ranging from -0.31 to -0.38 (mean: -0.36)
  and with the CR time delay of 2 to 3 days. Similar anti-correlations
  were found for the solar wind density and velocity characterized by
  the CR time lag of 4 and 1 day, respectively. The relationship was also
  established between the CR modulation and the area of the CIR-related CH
  with the CR time lag of 5 days after the central-meridian passage of CH.

---------------------------------------------------------
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.

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Title: Solar Differential Rotation Determined by Tracing Low and
    High Brightness Temperature Regions at 8 mm
Authors: Romštajn, I.; Brajša, R.; Wöhl, H.; Benz, A. O.; Temmer,
   M.; Roša, D.; Ruždjak, V.
2009CEAB...33...79R    Altcode:
  At the wavelength of 8 mm absorption features (Low brightness
  Temperature Regions, LTRs) and emission features (High brightness
  Temperature Regions, HTRs) can be traced for determination of solar
  rotation. From earlier studies it is known that about two thirds of LTRs
  are associated with Hα filaments. The goal of the present analysis is
  to determine the heights of these solar structures and their rotational
  velocities. We used the method for the simultaneous determination of
  the solar synodic rotation velocity and the height of tracers. The
  rotation velocities were determined by the linear least-square fit of
  their central meridian distances as a function of time. The mean value
  of the low brightness temperature regions' heights is about 45 600
  km. The results of solar rotation determined by tracing LTRs and HTRs
  are mutually compared and also compared with the results using other
  tracers and methods. The method for the simultaneous determination
  of the solar synodic rotation velocity and the height of the tracers
  could be applied properly only on LTRs, since a wide distribution
  over latitudes and central meridian distances of a large data set is
  necessary, which was not available for HTRs. Observational findings that
  HTRs rotate systematically faster than LTRs and the possibility that
  they can be observed at and outside the solar limb are consistent with
  relatively high altitudes of HTRs. It was concluded that the radiation
  mechanism of HTRs is thermal bremsstrahlung, probably associated with
  flaring active regions.

---------------------------------------------------------
Title: Triangulation of CME Source Region Locations on the Sun and
    Dependence on Spacecraft Observation Angles
Authors: Preiss, S.; Temmer, M.; Hanslmeier, A.
2009CEAB...33..125P    Altcode:
  STEREO-A, STEREO-B, and LASCO/SOHO observe coronal mass ejections
  (CMEs) from three different vantage points. On the basis of the radial
  plane-of-sky (POS) measurements of a CME in these three projection
  planes, the CME source region (SR) location was determined using the
  triangulation method of Temmeretal2009. As this triangulation method
  needs distance-time measurements in one POS as reference input, the
  determined SR varies with the change of the reference system. In the
  present study we vary the reference system, which shows the dependence
  of the resulting SR location of a CME on the spacecraft observation
  angles, and also reveals the limitation of the radial POS measurements.

---------------------------------------------------------
Title: Heights of solar tracers observed at 8 mm and an interpretation
    of their radiation
Authors: Brajša, R.; Romštajn, I.; Wöhl, H.; Benz, A. O.; Temmer,
   M.; Roša, D.
2009A&A...493..613B    Altcode:
  Context: At the wavelength of 8 mm, emissive features (high
  brightness-temperatrue regions, HTRs) and absorptive features
  (low brightness-temperature regions, LTRs) can be traced for the
  determining the solar rotation. From earlier studies it is known
  that about two thirds of LTRs are associated with Hα filaments. <BR
  />Aims: Thermal bremsstrahlung and gyromagnetic (cyclotron) radiation
  mechanism can be important for explaining the observed phenomena,
  so we determine the heights of solar structures and interpret their
  radiation mechanism(s). <BR />Methods: We use the method of simultaneous
  determination of the solar synodic rotation velocity and the height
  of tracers. The rotation velocities were determined by the linear
  least-square fit of their central meridian distance as a function of
  time. We used a procedure for calculating the brightness temperature for
  a given wavelength and model atmosphere, which integrates the radiative
  transfer equation for the thermal bremsstrahlung. <BR />Results:
  The mean value of the low brightness-temperature regions' heights
  is about 45 600 km. This height was used as input for constructing
  prominence and coronal condensation models, which, when assuming thermal
  bremsstrahlung as the radiation mechanism, yield a decrease in the
  brightness temperature of 2-14%, in agreement with observations. If the
  same radiation mechanism is considered, the models of the solar corona
  above active regions give an increase in the brightness temperature of
  5-19%, also in agreement with observations. In this case an indirect
  indication (from the rotational analysis) that the HTRs are located
  higher in the solar atmosphere than the LTRs was taken into account. <BR
  />Conclusions: The method for simultaneously determining the solar
  synodic rotation velocity and the height of tracers could have only
  been properly applied on LTRs, since a homogeneous distribution over
  latitudes and central meridian distances of a large enough data set is
  necessary. Thermal bremsstrahlung can explain both the LTR (prominences
  and coronal condensations) and HTR (ordinary active regions) phenomena
  observed at 8 mm. At this wavelength, thermal gyromagnetic emission
  is almost surely excluded as a possible radiation mechanism.

---------------------------------------------------------
Title: Cylindrical and Spherical Pistons as Drivers of MHD Shocks
Authors: Žic, Tomislav; Vršnak, Bojan; Temmer, Manuela; Jacobs, Carla
2008SoPh..253..237Z    Altcode: 2008SoPh..tmp..153Z
  We consider an expanding three-dimensional (3-D) piston as a driver
  of an MHD shock wave. It is assumed that the source-region surface
  accelerates over a certain time interval to achieve a particular maximum
  velocity. Such an expansion creates a large-amplitude wave in the
  ambient plasma. Owing to the nonlinear evolution of the wavefront, its
  profile steepens and after a certain time and distance a discontinuity
  forms, marking the onset of the shock formation. We investigate
  how the formation time and distance depend on the acceleration phase
  duration, the maximum expansion velocity (defining also acceleration),
  the Alfvén velocity (defining also Mach number), and the initial size
  of the piston. The model differs from the 1-D case, since in the 3-D
  evolution, a decrease of the wave amplitude with distance must be taken
  into account. We present basic results, focusing on the timing of the
  shock formation in the low- and high-plasma-beta environment. We find
  that the shock-formation time and the shock-formation distance are
  (1) approximately proportional to the acceleration phase duration;
  (2) shorter for a higher expansion velocity; (3) larger in a higher
  Alfvén speed environment; (4) only weakly dependent on the initial
  source size; (5) shorter for a stronger acceleration; and (6) shorter
  for a larger Alfvén Mach number of the source surface expansion. To
  create a shock causing a high-frequency type II burst and the Moreton
  wave, the source region expansion should, according to our results,
  achieve a velocity on the order of 1000 km s<SUP>−1</SUP> within a
  few minutes, in a low Alfvén velocity environment.

---------------------------------------------------------
Title: Multi-spacecraft Recovery of a Magnetic Cloud and its Origin
    From Magnetic Reconnection on the Sun
Authors: Möstl, C.; Farrugia, C. J.; Miklenic, C.; Temmer, M.; Galvin,
   A. B.; Luhmann, J. G.; Biernat, H. K.; Huttunen, K. E.; Leitner, M.;
   Nieves-Chinchilla, T.; Veronig, A.
2008AGUFMSH23B1634M    Altcode:
  Multi-point spacecraft observations of a magnetic cloud on May 22, 2007
  has given us the opportunity to apply a multi-spacecraft technique
  to infer the structure of this large-scale magnetic flux rope in
  the solar wind. Combining WIND and STEREO-B magnetic field and plasma
  measurements, since these spacecraft entered the ejecta, we construct a
  combined magnetic field map by integrating the Grad-Shafranov equation,
  this being one of the very first applications of this technique in
  the interplanetary context. From this we obtain robust results on the
  shape of the cross-section, the orientation and magnetic fluxes of the
  cloud. The only slightly "flattened" shape is discussed with respect
  to its heliospheric environment and theoretical expectations. We also
  relate these results to observations of the Solar source region and
  its associated two- ribbon flare on May 19, 2007 using Hα images from
  the Kanzelhöhe observatory, SOHO/MDI magnetograms and SECCHI/EUVI
  171~Å~images. We find a close correspondence between the magnetic
  flux reconnected in the flare and the poloidal flux of the magnetic
  cloud. The axial flux of the cloud agrees with the prediction of a
  recent 3D finite sheared arcade model to within a factor of 2, which
  is evidence for formation of at least half of the magnetic flux of the
  ejected flux rope during the eruption. We outline the relevance of
  this result to models of coronal mass ejection initiation, and find
  that to explain the solar and interplanetary observations elements
  from sheared-arcade as well as erupting-flux-rope models are needed.

---------------------------------------------------------
Title: A Flare-Generated Shock during a Coronal Mass Ejection on 24
    December 1996
Authors: Magdalenić, J.; Vršnak, B.; Pohjolainen, S.; Temmer, M.;
   Aurass, H.; Lehtinen, N. J.
2008SoPh..253..305M    Altcode: 2008SoPh..tmp..120M
  We present a multiwavelength study of the large-scale coronal
  disturbances associated with the CME - flare event recorded on 24
  December 1996. The kinematics of the shock wave signature, the type
  II radio burst, is analyzed and compared with the flare evolution
  and the CME kinematics. We employ radio dynamic spectra, position
  of the Nançay Radioheliograph sources, and LASCO-C1 observations,
  providing detailed study of this limb event. The obtained velocity of
  the shock wave is significantly higher than the contemporaneous CME
  velocity (1000 and 235 km s<SUP>−1</SUP>, respectively). Moreover,
  since the main acceleration phase of the CME took place 10 - 20 min
  after the shock wave was launched, we conclude that the shock wave
  on 24 December 1996 was probably not driven by the CME. However,
  the shock wave was closely associated with the flare impulsive phase,
  indicating that it was ignited by the energy release in the flare.

---------------------------------------------------------
Title: Investigation of geomagnetic and solar activity over time
    span 1960-2001
Authors: Verbanac, G.; Vrsnak, B.; Korte, M.; Mandea, M.; Temmer, M.
2008AGUFMSH13A1502V    Altcode:
  The solar-terrestrial relationship has been widely studied by means
  of space weather indices and various solar wind parameters. In this
  study we perform such an investigation over four decades (1960--2001)
  on the global scale, and for the first time on the regional scale as
  well. The variations regarded as the remaining external field signal
  (thereafter RES) and present in the European observatory annual means
  of the Northward, X, magnetic component is used as an indicator of
  the regional geomagnetic activity and are investigated regarding
  different processes occurring on the Sun. In order to understand how
  various geomagnetic activity indices respond to the interplanetary
  disturbances during different periods of the solar cycle, the annual
  means of the solar activity index, F10.7, and geomagnetic Ap and Dst
  indices, are studied. The indices are inherently complex since they
  include contributions from different solar phenomena. By studying
  the cross-correlations we aim to distinguish between different
  generation mechanisms. The relationships between the solar parameter
  F10.7 and RES, Dst, Ap, characterized by high cross-correlation
  coefficients, suggest the possibility to evaluate the behaviour of
  these geomagnetic parameters on short timescale. We found finite
  time lags among the investigated parameters. Our study suggests a
  one year delay of both RES and Dst after F10.7. The Ap is clearly
  delayed for about two years with respect to F10.7 and about one year
  with respect to Dst and RES. This indicate that the Ap responds to
  the solar activity in a different manner than Dst and RES, which are
  dominated by the coronal mass ejections activity. On the other hand,
  it seems that Ap is more sensitive to the high--speed streams (HSS)
  and Alfvenic waves present in HSS. The existence of time lags gives
  us the possibility to forecast different parameters. Importantly, the
  proposed forecasting procedure offers the possibility to reconstruct
  the F10.7 from the inferred geomagnetic activity for the epochs prior
  to solar activity monitoring. This study contributes to understanding
  some physical processes on the Sun that cause the perturbations in the
  near-Earth interplanetary space and consequently in the Earth's magnetic
  field. Moreover such investigations may provide a better insight into
  the time evolution of the open and closed solar magnetic field, and into
  long term changes in the solar activity with related physical processes.

---------------------------------------------------------
Title: Global thermospheric density variations caused by high-speed
    solar wind streams during the declining phase of solar cycle 23
Authors: Lei, Jiuhou; Thayer, Jeffrey P.; Forbes, Jeffrey M.; Sutton,
   Eric K.; Nerem, R. Steven; Temmer, Manuela; Veronig, Astrid M.
2008JGRA..11311303L    Altcode:
  Thermosphere densities at 400 km altitude from accelerometer
  measurements on the CHAMP satellite are used to investigate oscillations
  at periods of less than 13 days during the declining phase of solar
  cycle 23 (2002-2007). The periodic oscillations around 7 and 9 days in
  neutral density tend to occur during the latter part of the declining
  solar cycle when periodically recurrent fast streams in the solar
  wind modulate the level of geomagnetic activity in the geospace
  environment. It is interesting that the periodic oscillations in
  neutral density are felt globally and are proportional to the periodic
  Kp perturbations at the same frequency. Moreover, the periods of 7
  and 9 days apparently reflect subharmonics of the 27-day rotation
  and may be related to the longitudinal distribution of coronal holes;
  however the comparison of the temporal evolution of the periodicities
  between the coronal holes area and solar wind in 2005 indicates that
  their relationships are rather complex.

---------------------------------------------------------
Title: Two-spacecraft reconstruction of a magnetic cloud and
    comparison to its solar source
Authors: Möstl, C.; Miklenic, C.; Farrugia, C. J.; Temmer, M.;
   Veronig, A.; Galvin, A. B.; Vršnak, B.; Biernat, H. K.
2008AnGeo..26.3139M    Altcode:
  This paper compares properties of the source region with those inferred
  from satellite observations near Earth of the magnetic cloud which
  reached 1 AU on 20 November 2003. We use observations from space
  missions SOHO and TRACE together with ground-based data to study
  the magnetic structure of the active region NOAA 10501 containing
  a highly curved filament, and determine the reconnection rates and
  fluxes in an M4 flare on 18 November 2003 which is associated with
  a fast halo CME. This event has been linked before to the magnetic
  cloud on 20 November 2003. We model the near-Earth observations with
  the Grad-Shafranov reconstruction technique using a novel approach in
  which we optimize the results with two-spacecraft measurements of the
  solar wind plasma and magnetic field made by ACE and WIND. The two
  probes were separated by hundreds of Earth radii. They pass through
  the axis of the cloud which is inclined -50 degree to the ecliptic. The
  magnetic cloud orientation at 1 AU is consistent with an encounter with
  the heliospheric current sheet. We estimate that 50% of its poloidal
  flux has been lost through reconnection in interplanetary space. By
  comparing the flare ribbon flux with the original cloud fluxes we infer
  a flux rope formation during the eruption, though uncertainties are
  still significant. The multi-spacecraft Grad-Shafranov method opens
  new vistas in probing of the spatial structure of magnetic clouds in
  STEREO-WIND/ACE coordinated studies.

---------------------------------------------------------
Title: Large-scale Coronal Waves Observed with EUVI/STEREO
Authors: Veronig, A.; Temmer, M.; Vrsnak, B.
2008ESPM...12.2.97V    Altcode:
  We report first observations and analysis of flare/CME associated
  large-scale coronal waves (so-called "EIT waves") observed with
  high time cadence by the EUVI instruments onboard the recent STEREO
  mission. The EIT instrument onboard SOHO for the first time directly
  imaged global disturbances in the solar corona, but the observations
  are severely hampered by the low cadence of EIT (12-15 min). Thus,
  the nature and origin of these large-scale disturbances are still
  not sufficiently constraint by observations, and it is an intense
  matter of debate whether EIT waves: a) are the coronal counterparts of
  Moreton waves observed in the chromosphere; b) are caused by the flare
  explosive energy release or by the erupting CME; c) are waves at all or
  rather propagating disturbances related to magnetic field line opening
  and restructuring associated with the CME lift-off. The high cadence
  full-disk coronal imaging by the EUVI instruments on the twin STEREO
  spacecraft provide us with the unprecedented opportunity to study the
  dynamics and origin of flare/CME associated coronal waves. We present
  first studies of global coronal waves observed with EUVI finding wave
  deceleration, indicative of an MHD blast wave (Veronig et al. 2008,
  ApJ Lett., in press).

---------------------------------------------------------
Title: Relation between CME SchmiederAcceleration Profile and Flare
    Energy Release derived from Combined STEREO and RHESSI Observations
Authors: Temmer, M.; Veronig, A. M.; Vrsnak, B.
2008ESPM...12.2.96T    Altcode:
  In the standard flare/CME picture magnetic reconnection occurs in
  a current sheet formed behind the CME, which may provide a feedback
  relationship between both phenomena. To study the relationship of the
  large-scale CME acceleration and the energy release in the associated
  flare we analyze three well observed events. The observations cover
  the early (low corona) evolution of the CMEs with the EUVI instruments
  aboard the twin STEREO spacecraft and the RHESSI hard X-ray emission
  of the associated flare. Since the flare hard X-rays are due to fast
  electrons, they provide the most direct indicator of the evolution of
  the flare energy release in the flare. The results are compared to case
  studies for halo-CMEs where a close synchronization between the CME
  acceleration and the flare energy release was found (Temmer et al.,
  ApJ, 2008, 673, L95).

---------------------------------------------------------
Title: High-Cadence Observations of a Global Coronal Wave by
    STEREO EUVI
Authors: Veronig, Astrid M.; Temmer, Manuela; Vršnak, Bojan
2008ApJ...681L.113V    Altcode: 2008arXiv0806.0710V
  We report a large-scale coronal wave (so-called EIT wave) observed
  with high cadence by EUVI on board STEREO in association with the GOES
  B9.5 flare and double CME event on 2007 May 19. The EUVI instruments
  provide us with the unprecedented opportunity to study the dynamics of
  flare/CME associated coronal waves. The coronal wave under study reveals
  deceleration, indicative of a freely propagating MHD wave. Complementary
  analysis of the associated flare and erupting filament/CME hint at wave
  initiation by the CME expanding flanks, which drive the wave only over
  a limited distance. The associated flare is very weak and occurs too
  late to account for the wave initiation.

---------------------------------------------------------
Title: Analysis of a Moreton Wave Associated with the X17.2/4B
    Flare/CME of 28-10-2003
Authors: Muhr, M.; Temmer, M.; Veronig, A.; Vršnak, B.; Hanslmeier, A.
2008CEAB...32...79M    Altcode:
  The fast Moreton wave of 28-Oct-2003 associated with the extreme X17.2
  solar flare/CME event is studied. It can be followed in four sectors,
  spanning almost over 360° on the visible solar disc. The mean wave
  velocity lies in the range of v∼900-1000 km s^{-1}. We find two
  wave ignition centres on opposite edges of the source region, which
  may indicate that the wave is driven by the CME expanding flanks.

---------------------------------------------------------
Title: Acceleration in Fast Halo CMEs and Synchronized Flare HXR
    Bursts
Authors: Temmer, M.; Veronig, A. M.; Vršnak, B.; Rybák, J.; Gömöry,
   P.; Stoiser, S.; Maričić, D.
2008ApJ...673L..95T    Altcode:
  We study two well-observed, fast halo CMEs, covering the full CME
  kinematics including the initiation and impulsive acceleration phase,
  and their associated flares. We find a close synchronization between the
  CME acceleration profile and the flare energy release as indicated by
  the RHESSI hard X-ray flux onsets, as well as peaks occur simultaneously
  within 5 minutes. These findings indicate a close physical connection
  between both phenomena and are interpreted in terms of a feedback
  relationship between the CME dynamics and the reconnection process in
  the current sheet beneath the CME.

---------------------------------------------------------
Title: Large-scale coronal waves observed with STEREO/EUVI
Authors: Veronig, Astrid; Temmer, Manuela; Vrsnak, Bojan
2008cosp...37.3328V    Altcode: 2008cosp.meet.3328V
  The EUVI instruments onboard the twin STEREO spacecraft provide
  high-cadence full-disk imaging of the solar atmosphere with four
  different filters at EUV wavelengths. These observations are highly
  suitable to study the kinematics and dynamics of flare/CME associated
  coronal waves, so-called "EIT waves". We present a detailed analysis
  of one coronal wave captured by the EUVI instruments, with particular
  emphasis on the wave dynamics and its connection to the associated
  flare (RHESSI hard X-rays) and CME (STEREO COR1) in terms of blast
  wave versus driven wave scenario.

---------------------------------------------------------
Title: Synchronization between the CME acceleration and the energy
    release in the associated flare
Authors: Temmer, Manuela; Veronig, Astrid; Vrsnak, Bojan
2008cosp...37.3167T    Altcode: 2008cosp.meet.3167T
  In the standard flare/CME picture magnetic reconnection occurs in a
  current sheet formed behind the CME, which is indicative of a feedback
  relationship between both phenomena. We analyze two X-class flare/CME
  events which were well covered by RHESSI hard X-ray observations,
  and the early evolution of the CMEs could be observed in TRACE and
  GOES/SXI images. Since the flare hard X-rays are due to fast electrons,
  they provide the most direct indicator of the evolution of the energy
  release in the flare. This data set enables us to study in detail
  the relationship of the large-scale CME acceleration and the energy
  release in the associated flare.

---------------------------------------------------------
Title: On the relation between in situ observations of a magnetic
    cloud and its solar source
Authors: Christiane, Miklenic; Möstl, Christian; Temmer, Manuela;
   Veronig, Astrid; Farrugia, Charles; Biernat, Helfried K.
2008cosp...37..543C    Altcode: 2008cosp.meet..543C
  During flare/CME events, fast plasma clouds and shocks may be generated,
  which propagate through interplanetary space. Interplanetary coronal
  mass ejections, which contain a magnetic cloud, can induce, if
  Earth-directed, geomagnetic storms, which can cause deleterious effects
  on space-borne and ground-based installations. Since our dependency
  on space-borne technical equipment is increasing, the importance of
  reliable space weather forecasts is indisputable. To achieve better
  space weather forecasts, it is essential to understand the relation
  between solar source observations and in situ observations of the
  magnetic cloud. For the CME/flare event on July 6, 2006, we present
  a detailed analysis of the magnetic field configuration of the solar
  source and the reconnection flux of the flare, which is related to the
  associated magnetic cloud properties observed at the Earth. The event is
  well covered by multi-wavelength observations from SoHO, TRACE, RHESSI,
  as well as ground-based Hα observations. The magnetic field geometry
  of the magnetic cloud at 1 AU is modeled with the Grad-Shafranov
  reconstruction technique, applying observations from two satellites,
  namely WIND and ACE.

---------------------------------------------------------
Title: Projection effects in coronal mass ejections studied with
    STEREO and SoHO
Authors: Temmer, Manuela; Preiss, Stefanie; Veronig, Astrid; Vrsnak,
   Bojan
2008cosp...37.3168T    Altcode: 2008cosp.meet.3168T
  The STEREO mission consists of two identical satellites, positioned
  ahead (A) and behind (B) the Earth, which observe the Sun from viewing
  angles different from that of LASCO aboard SoHO (positioned at L1). The
  kinematics (speed) and width of a coronal mass ejection (CME) is derived
  by measuring distinct CME features observed in projection against the
  plane of sky. As STEREO-A, STEREO-B, and LASCO/SoHO, observe a CME
  from three different viewing angles, the resulting CME kinematics and
  widths differ. By combining the observations from the three satellites
  we study for several well observed CMEs the importance of projection
  effects for the CME kinematics and expansion.

---------------------------------------------------------
Title: Two-spacecraft Reconstruction of a Magnetic Cloud and
    Comparison to its Solar Source
Authors: Moestl, C.; Miklenic, C.; Farrugia, C.; Temmer, M.; Veronig,
   A.; Galvin, A.; Biernat, H.
2007AGUFMSH32A0781M    Altcode:
  Relating observations of coronal mass ejections (CMEs) and their
  interplanetary counterpart (ICMEs) is a centerpoint of Sun-Earth
  connection studies and our ability to forecast space weather. Here we
  focus on the ICME containing a magnetic cloud which reached Earth on
  November 20, 2003 and gave rise to the strongest storm of solar cycle
  23, with a minimum Dst of -472 nT. Its strong geoeffective impact
  came about two weeks after the massive eruptions known as "Halloween"
  events resulted in comparable geo-effects. The aims of this study
  are threefold. We first apply an advanced methodology to analyze with
  diverse observations the event on the solar disk, which occurred on
  Nov 18, 2003, and was associated with an M4 flare and a halo CME. We
  then employ a Grad-Shafranov reconstruction technique to model the
  magnetic field geometry at 1 AU. To this end, we use measurements
  acquired by spacecraft WIND and ACE, ~400 RE apart. We show how these
  twin-spacecraft observations allow us to optimize the reconstructed
  map. Finally, we relate the solar to the interplanetary observations,
  paying special attention to the orientations and the magnetic fluxes
  involved at the two locales. By comparing the flare with the original
  cloud fluxes we infer a possible in-situ flux rope formation during
  the eruption, though uncertainties are still significant. The error
  margins in the comparisons are also carefully assessed.

---------------------------------------------------------
Title: An Interpretation of the Coronal Holes' Visibility in the
    Millimeter Wavelength Range
Authors: Brajša, R.; Benz, A. O.; Temmer, M.; Jurdana-Šepić, R.;
   Šaina, B.; Wöhl, H.
2007SoPh..245..167B    Altcode:
  Various observations indicate that coronal holes generally appear as low
  brightness temperature regions (LTRs) in the centimeter and millimeter
  wavelength ranges. However, within their borders local enhancements of
  radiation, that is, high brightness temperature regions (HTRs), often
  occur. The theory behind the described behavior is not fully understood
  and therefore we analyze full-disk solar images obtained at a wavelength
  of 8 mm at Metsähovi Radio Observatory and compare them with data
  simultaneously taken in other wavelength ranges. The observational
  finding that the average brightness temperature of coronal holes is
  not much different from the quiet-Sun level (with localized deviations
  toward higher and lower intensities on the order of a few percent)
  is compared with theoretical models of the thermal bremsstrahlung
  radiation originating in the solar chromosphere, transition region,
  and corona. Special attention is devoted to the interpretation of the
  localized enhancements of radiation observed inside coronal holes at
  millimeter wavelengths. The main conclusion is that the most important
  contribution to the brightness temperature comes from an increased
  density in the transition region and low corona (i.e., at the heights
  where the temperature is below 10<SUP>6</SUP> K). This can explain
  both the LTRs and HTRs associated with coronal holes.

---------------------------------------------------------
Title: Periodic Appearance of Coronal Holes and the Related Variation
    of Solar Wind Parameters
Authors: Temmer, Manuela; Vršnak, Bojan; Veronig, Astrid M.
2007SoPh..241..371T    Altcode:
  We compared the variability of coronal hole (CH) areas (determined
  from daily GOES/SXI images) with solar wind (daily ACE data) and
  geomagnetic parameters for the time span 25 January 2005 until 11
  September 2005 (late declining phase of solar cycle 23). Applying
  wavelet spectral analysis, a clear 9-day period is found in the
  CH time series. The GOES/SXI image sequence suggests that this
  periodic variation is caused by a mutual triangular distribution of
  CHs ∼120° apart in longitude. From solar wind parameters a 9-day
  periodicity was obtained as well, simultaneously with the 9-day period
  in the CH area time series. These findings provide strong evidence
  that the 9-day period in solar wind parameters, showing up as higher
  harmonic of the solar rotation frequency, is caused by the "periodic"
  longitudinal distribution of CHs on the Sun recurring for several
  solar rotations. The shape of the wavelet spectrum from the Dst index
  matches only weakly with that from the CH areas and is more similar to
  the wavelet spectrum of the solar wind magnetic field magnitude. The
  distinct 9-day period does not show up in sunspot group areas which
  gives further evidence that the solar wind modulation is strongly
  related to CH areas but not to active region complexes. The wavelet
  power spectra for the whole ACE data range (∼1998 - 2006) suggest that
  the 9-day period is not a singular phenomenon occurring only during
  a specific time range close to solar minimum but is occasionally also
  present during the maximum and decay phase of solar cycle 23. The main
  periods correspond to the solar rotation (27<SUP>d</SUP>) as well as
  to the second (13.5<SUP>d</SUP>) and third (9<SUP>d</SUP>) harmonic.

---------------------------------------------------------
Title: Acceleration Phase of Coronal Mass Ejections: I. Temporal
    and Spatial Scales
Authors: Vršnak, Bojan; Maričić, Darije; Stanger, Andrew L.;
   Veronig, Astrid M.; Temmer, Manuela; Roša, Dragan
2007SoPh..241...85V    Altcode:
  We study kinematics of 22 coronal mass ejections (CMEs) whose
  motion was traced from the gradual pre-acceleration phase up to
  the post-acceleration stage. The peak accelerations in the studied
  sample range from 40, up to 7000 m s<SUP>−2</SUP>, and are inversely
  proportional to the acceleration phase duration and the height range
  involved. Accelerations and velocities are, on average, larger in CMEs
  launched from a compact source region. The acceleration phase duration
  is proportional to the source region dimensions; i.e., compact CMEs
  are accelerated more impulsively. Such behavior is interpreted as
  a consequence of stronger Lorentz force and shorter Alfvén time
  scales involved in compact CMEs (with stronger magnetic field and
  larger Alfvén speed being involved at lower heights). CMEs with
  larger accelerations and velocities are on average wider, whereas the
  widths are not related to the source region dimensions. Such behavior is
  explained in terms of the field pile-up ahead of the erupting structure,
  which is more effective in the case of a strongly accelerated structure.

---------------------------------------------------------
Title: Acceleration Phase of Coronal Mass Ejections:
    II. Synchronization of the Energy Release in the Associated Flare
Authors: Maričić, Darije; Vršnak, Bojan; Stanger, Andrew L.;
   Veronig, Astrid M.; Temmer, Manuela; Roša, Dragan
2007SoPh..241...99M    Altcode:
  We analyze the relationship between the acceleration of coronal mass
  ejections (CMEs) and the energy release in associated flares, employing
  a sample of 22 events in which the CME kinematics were measured from
  the pre-eruption stage up to the post-acceleration phase. The data
  show a distinct correlation between the duration of the acceleration
  phase and the duration of the associated soft X-ray (SXR) burst rise,
  whereas the CME peak acceleration and velocity are related to the
  SXR peak flux. In the majority of events the acceleration started
  earlier than the SXR burst, and it is usually prolonged after the
  SXR burst maximum. In about one half of the events the acceleration
  phase is very closely synchronized with the fastest growth of the SXR
  burst. An additional one quarter of the events may be still considered
  as relatively well-synchronized, whereas in the remaining quarter of the
  events there is a considerable mismatch. The results are interpreted
  in terms of the feedback relationship between the CME dynamics and
  the reconnection process in the wake of the CME.

---------------------------------------------------------
Title: Coronal Holes and Solar Wind High-Speed Streams:
    II. Forecasting the Geomagnetic Effects
Authors: Vršnak, Bojan; Temmer, Manuela; Veronig, Astrid M.
2007SoPh..240..331V    Altcode:
  We present a simple method of forecasting the geomagnetic storms caused
  by high-speed streams (HSSs) in the solar wind. The method is based
  on the empirical correlation between the coronal hole area/position
  and the value of the Dst index, which is established in a period of
  low interplanetary coronal mass ejection (ICME) activity. On average,
  the highest geomagnetic activity, i.e., the minimum in Dst, occurs
  four days after a low-latitude coronal hole (CH) crosses the central
  meridian. The amplitude of the Dst dip is correlated with the CH area
  and depends on the magnetic polarity of the CH due to the Russell -
  McPherron effect. The Dst variation may be predicted by employing the
  expression Dst(t)=(−65±25×cos λ)[A(t<SUP>*</SUP>)]<SUP>0.5</SUP>,
  where A(t<SUP>*</SUP>) is the fractional CH area measured in the
  central-meridian slice [−10°,10°] of the solar disc, λ is the
  ecliptic longitude of the Earth, ± stands for positive/negative CH
  polarity, and t−t<SUP>*</SUP>=4 days. In periods of low ICME activity,
  the proposed expression provides forecasting of the amplitude of the
  HSS-associated Dst dip to an accuracy of ≈30%. However, the time of
  occurrence of the Dst minimum cannot be predicted to better than ±2
  days, and consequently, the overall mean relative difference between
  the observed and calculated daily values of Dst ranges around 50%.

---------------------------------------------------------
Title: Coronal Holes and Solar Wind High-Speed Streams: I. Forecasting
    the Solar Wind Parameters
Authors: Vršnak, Bojan; Temmer, Manuela; Veronig, Astrid M.
2007SoPh..240..315V    Altcode:
  We analyze the relationship between the coronal hole (CH) area/position
  and physical characteristics of the associated corotating high-speed
  stream (HSS) in the solar wind at 1 AU. For the analysis we utilize the
  data in the period DOY 25 - 125 of 2005, characterized by a very low
  coronal mass ejection (CME) activity. Distinct correlations between
  the daily averaged CH parameters and the solar wind characteristics
  are found, which allows us to forecast the solar wind velocity v,
  proton temperature T, proton density n, and magnetic field strength B,
  several days in advance in periods of low CME activity. The forecast
  is based on monitoring fractional areas A, covered by CHs in the
  meridional slices embracing the central meridian distance ranges
  [−40°,−20°], [−10°,10°], and [20°,40°]. On average, the
  peaks in the daily values of n, B, T, and v appear delayed by 1, 2,
  3, and 4 days, respectively, after the area A attains its maximum
  in the central-meridian slice. The peak values of the solar wind
  parameters are correlated to the peak values of A, which provides
  also forecasting of the peak values of n, B, T, and v. The most
  accurate prediction can be obtained for the solar wind velocity, for
  which the average relative difference between the calculated and the
  observed peak values amounts to \overline{\vertδ\vert}≈10 %. The
  forecast reliability is somewhat lower in the case of T, B, and n (
  \overline{\vertδ\vert}≈20 , 30, and 40%, respectively). The space
  weather implications are discussed, including the perspectives for
  advancing the real-time calculation of the Sun - Earth transit times
  of coronal mass ejections and interplanetary shocks, by including more
  realistic real-time estimates of the solar wind characteristics.

---------------------------------------------------------
Title: Analysis of the Flare Wave Associated with the 3B/X3.8 Flare
    of January 17, 2005
Authors: Thalmann, J. K.; Veronig, A. M.; Temmer, M.; Vršnak, B.;
   Hanslmeier, A.
2007CEAB...31..187T    Altcode:
  The flare wave associated with the 3B/X3.8 flare and coronal mass
  ejection (CME) of January 17, 2005 are studied using imaging data
  in the Hα and EUV spectral channels. Due to the high-cadence Hα
  observations from Kanzelhöhe Solar Observatory (KSO), a distinct
  Moreton wave can be identified in ∼40 Hα frames over a period
  of ∼7 minutes. The associated coronal EIT wave is identifiable in
  only one EUV frame and appears close to the simultaneously observed
  Moreton wave front, indicating that they are closely associated
  phenomena. Beside the morphology of the wave across the solar disc
  (covering an angular extend of ∼130°), the evolution in different
  directions is studied to analyse the influence of a coronal hole (CH)
  on the wave propagation. The Moreton wave shows a decelerating character
  which can be interpreted in terms of a freely propagating fast-mode MHD
  shock. The parts of the wave front moving towards the CH show a lower
  initial and mean speed, and a greater amount of deceleration than the
  segments moving into the undisturbed direction. This is interpreted
  as the tendency of high Alfvén velocity regions to influence the
  propagation of wave packets.

---------------------------------------------------------
Title: On the Visibility of Coronal Holes in Microwaves
Authors: Brajša, R.; Benz, A. O.; Temmer, M.; Jurdana-Šepić, R.;
   Šaina, B.; Wöhl, H.; Ruždjak, V.
2007CEAB...31..219B    Altcode:
  Previous observations indicate that coronal holes generally appear as
  low brightness temperature regions in microwaves. However, within their
  borders local enhancements of radiation often occur. This is confirmed
  by comparing a full-disc solar image obtained at 37 GHz on 27 May 1993
  with full-disc solar images obtained at various wavelengths. Microwave
  brightness temperatures of three coronal holes are determined and
  interpreted.

---------------------------------------------------------
Title: Spatial Restriction to HXR Footpoint Locations by Reconnection
    Site Geometries
Authors: Temmer, M.; Vršnak, B.; Veronig, A.; Miklenic, M.
2007CEAB...31...49T    Altcode: 2007astro.ph..1203T
  It is assumed that HXR sources map to the primary energy release site in
  flares where particle acceleration occurs. Strong HXR sources are mostly
  observed at confined regions along the reconnecting magnetic arcade. We
  make a general approach on how the geometry of the reconnecting current
  sheet (CS) may influence the strength and localization of observed HXR
  sources. For this we use results from an analysis on the 3B/X3.8 flare
  on January 17, 2005 (Temmer et al., 2007), as well as measurements from
  the associated CME. Due to the close match of the CME acceleration
  profile and the flare HXR flux, we suppose that the CME might play a
  certain role in modifying the geometry of the CS (“symmetric” versus
  “asymmetric” vertically stretched CS). This could be the driver for
  “guiding” the accelerated particles to confined areas along the
  flaring arcade and might explain the spatially limited occurrence of
  strong HXR sources in comparison to elongated ribbons as seen in Hα
  and UV.

---------------------------------------------------------
Title: Energy Release Rates along Hα Flare Ribbons and the Location
    of Hard X-Ray Sources
Authors: Temmer, M.; Veronig, A. M.; Vršnak, B.; Miklenic, C.
2007ApJ...654..665T    Altcode:
  Local reconnection and energy release rates for an X3.8 flare that
  occurred on 2005 January 17 are derived. In particular, we distinguish
  between Hα flare ribbon segments that were accompanied by RHESSI
  hard X-ray (HXR) footpoints and those without HXRs. We find that the
  reconnection and energy release rates are not uniform along the flare
  ribbons but much larger at the locations where the HXR footpoints are
  observed. The difference is about 2 orders of magnitude in the case of
  the energy release rates and 1 order of magnitude for the reconnection
  rates (with peak values up to 8 kV m<SUP>-1</SUP>). These differences
  are enough to explain the different flare morphologies typically
  observed in HXRs (compact footpoints) and Hα/UV (extended ribbons)
  by the limited dynamic range of present HXR instruments. Our results
  are consistent with a scenario in which the electrons are accelerated
  primarily along a certain subsystem of magnetic loops as outlined by
  the HXR footpoints, and only a minor fraction (for the 2005 January
  17 flare estimated to be about 1/15) go into the large flare arcade
  outlined by the Hα ribbons and EUV postflare loops.

---------------------------------------------------------
Title: Interaction of a Moreton/EIT Wave and a Coronal Hole
Authors: Veronig, Astrid M.; Temmer, Manuela; Vršnak, Bojan; Thalmann,
   Julia K.
2006ApJ...647.1466V    Altcode: 2006astro.ph..4613V
  We report high-cadence Hα observations of a distinct Moreton wave
  observed at Kanzelhöhe Solar Observatory associated with the 3B/X3.8
  flare and coronal mass ejection (CME) event of 2005 January 17. The
  Moreton wave can be identified in about 40 Hα frames over a period of
  7 minutes. The EIT wave is observed in only one frame, but the derived
  propagation distance is close to that of the simultaneously measured
  Moreton wave fronts, indicating that they are closely associated
  phenomena. The large angular extent of the Moreton wave allows us to
  study the wave kinematics in different propagation directions with
  respect to the location of a polar coronal hole (CH). In particular, we
  find that the wave segment whose propagation direction is perpendicular
  to the CH boundary (“frontal encounter”) is stopped by the CH, which
  is in accordance with observations reported from EIT waves. However,
  we also find that at a tongue-shaped edge of the coronal hole, where
  the front orientation is perpendicular to the CH boundary (the wave
  “slides along” the boundary), the wave signatures can be found up
  to 100 Mm inside the CH. These findings are briefly discussed in the
  frame of recent modeling results.

---------------------------------------------------------
Title: Shrinking and Cooling of Flare Loops in a Two-Ribbon Flare
Authors: Vršnak, Bojan; Temmer, Manuela; Veronig, Astrid; Karlický,
   Marian; Lin, Jun
2006SoPh..234..273V    Altcode:
  We analyze the evolution of the flare/postflare-loop system in the
  two-ribbon flare of November 3, 2003, utilizing multi-wavelength
  observations that cover the temperature range from several tens of
  MK down to 10<SUP>4</SUP> K. A non-uniform growth of the loop system
  enables us to identify analogous patterns in the height-time, h(t),
  curves measured at different temperatures. The "knees," "plateaus,"
  and "bends" in a higher-temperature curve appear after a certain time
  delay at lower heights in a lower-temperature curve. We interpret such
  a shifted replication as a track of a given set of loops (reconnected
  field lines) while shrinking and cooling after being released from the
  reconnection site. Measurements of the height/time shifts between h(t)
  curves of different temperatures provide a simultaneous estimate of
  the shrinkage speed and cooling rate in a given temperature domain,
  for a period of almost ten hours after the flare impulsive phase. From
  the analysis we find the following: (a) Loop shrinkage is faster at
  higher temperatures - in the first hour of the loop-system growth,
  the shrinkage velocity at 5 MK is 20 - 30 km s<SUP>−1</SUP>, whereas
  at 1 MK it amounts to 5 km s<SUP>−1</SUP>; (b) Shrinking becomes
  slower as the flare decays - ten hours after the impulsive phase,
  the shrinkage velocity at 5 MK becomes 5 km s<SUP>−1</SUP>; (c) The
  cooling rate decreases as the flare decays - in the 5 MK range it is
  1 MK min<SUP>−1</SUP> in the first hour of the loop-system growth,
  whereas ten hours later it decreases to 0.2 MK min<SUP>−1</SUP>;
  (d) During the initial phase of the loop-system growth, the cooling
  rate is larger at higher temperatures, whereas in the late phases
  the cooling rate apparently does not depend on the temperature; (e)
  A more detailed analysis of shrinking/cooling around one hour after
  the impulsive phase reveals a deceleration of the loop shrinkage,
  amounting to ā ≈ 10 m s<SUP>−2</SUP> in the T &lt; 5 MK range;
  (f) In the same interval, conductive cooling dominates down to T ≈
  3 MK, whereas radiation becomes dominant below T ≈ 2 MK; (g) A few
  hours after the impulsive phase, radiation becomes dominant across the
  whole T &lt; 5 MK range. These findings are compared with results of
  previous studies and discussed in the framework of relevant models.

---------------------------------------------------------
Title: Multi-wavelength study of coronal waves associated with the
    CME-flare event of 3 November 2003
Authors: Vršnak, B.; Warmuth, A.; Temmer, M.; Veronig, A.;
   Magdalenić, J.; Hillaris, A.; Karlický, M.
2006A&A...448..739V    Altcode:
  The large flare/CME event that occurred close to the west solar limb on
  3 November 2003 launched a large-amplitude large-scale coronal wave that
  was observed in Hα and Fe xii 195 Å spectral lines, as well as in the
  soft X-ray and radio wavelength ranges. The wave also excited a complex
  decimeter-to-hectometer type II radio burst, revealing the formation of
  coronal shock(s). The back-extrapolation of the motion of coronal wave
  signatures and the type II burst sources distinctly marks the impulsive
  phase of the flare (the hard X-ray peak, drifting microwave burst,
  and the highest type III burst activity), favoring a flare-ignited
  wave scenario. On the other hand, comparison of the kinematics of
  the CME expansion with the propagation of the optical wave signatures
  and type II burst sources shows a severe discrepancy in the CME-driven
  scenario. However, the CME is quite likely associated with the formation
  of an upper-coronal shock revealed by the decameter-hectometer type II
  burst. Finally, some six minutes after the launch of the first coronal
  wave, another coronal disturbance was launched, exciting an independent
  (weak) decimeter-meter range type II burst. The back-extrapolation
  of this radio emission marks the revival of the hard X-ray burst,
  and since there was no CME counterpart, it was clearly ignited by the
  new energy release in the flare.

---------------------------------------------------------
Title: Hemispheric sunspot numbers {R<SUB>n</SUB>} and {R<SUB>s</SUB>}
from 1945-2004: catalogue and N-S asymmetry analysis for solar
    cycles 18-23
Authors: Temmer, M.; Rybák, J.; Bendík, P.; Veronig, A.; Vogler,
   F.; Otruba, W.; Pötzi, W.; Hanslmeier, A.
2006A&A...447..735T    Altcode:
  From sunspot drawings provided by the Kanzelhöhe Solar Observatory,
  Austria, and the Skalnaté Pleso Observatory, Slovak Republic, we
  extracted a data catalogue of hemispheric Sunspot Numbers covering
  the time span 1945-2004. The validated catalogue includes daily,
  monthly-mean, and smoothed-monthly relative sunspot numbers
  for the northern and southern hemispheres separately and is
  available for scientific use. These data we then investigated with
  respect to north-south asymmetries for almost 6 entire solar cycles
  (Nos. 18-23). For all the cycles studied, we found that the asymmetry
  based on the absolute asymmetry index is enhanced near the cycle
  maximum, which contradicts to previous results that are based on the
  normalized asymmetry index. Moreover, the weak magnetic interdependence
  between the two solar hemispheres is confirmed by their self-contained
  evolution during a cycle. For the time span 1945-2004, we found that
  the cycle maxima and also the declining and increasing phases are
  clearly shifted, whereas the minima seem to be in phase for both
  hemispheres. The asymmetric behavior reveals no obvious connection
  to either the sunspot cycle period of ~11- or the magnetic cycle of
  ~22-years. The most striking excess of activity is observed for the
  northern hemisphere in cycles 19 and 20.

---------------------------------------------------------
Title: X-ray sources and magnetic reconnection in the X3.9 flare of
    2003 November 3
Authors: Veronig, A. M.; Karlický, M.; Vršnak, B.; Temmer, M.;
   Magdalenić, J.; Dennis, B. R.; Otruba, W.; Pötzi, W.
2006A&A...446..675V    Altcode:
  Context: .Recent RHESSI observations indicate an apparent altitude
  decrease of flare X-ray loop-top (LT) sources before changing to the
  commonly observed upward growth of the flare loop system.<BR /> Aims:
  .We performed a detailed study of the LT altitude decrease for one well
  observed flare in order to find further hints on the physics of this
  phenomenon and how it is related to the magnetic reconnection process in
  solar flares.<BR /> Methods: .RHESSI X-ray source motions in the 2003
  November 3, X3.9 flare are studied together with complementary data
  from SXI, EIT, and Kanzelhöhe Hα. We particularly concentrate on the
  apparent altitude decrease of the RHESSI X-ray LT source early in the
  flare and combine kinematical and X-ray spectral analysis. Furthermore,
  we present simulations from a magnetic collapsing trap model embedded
  in a standard 2-D magnetic reconnection model of solar flares.<BR />
  Results: .We find that at higher photon energies the LT source is
  located at higher altitudes and shows higher downward velocities
  than at lower energies. The mean downward velocities range from
  14 km s<SUP>-1</SUP> in the RHESSI 10-15 keV energy band to 45 km
  s<SUP>-1</SUP> in the 25-30 keV band. For this flare, the LT altitude
  decrease was also observed by the SXI instrument with a mean speed of
  12 km s<SUP>-1</SUP>. RHESSI spectra indicate that during the time
  of LT altitude decrease the emission of the LT source is thermal
  bremsstrahlung from a "superhot" plasma with temperatures increasing
  from 35 MK to 45 MK and densities of the order of 10<SUP>10</SUP>
  cm<SUP>-3</SUP>. The temperature does not significantly increase
  after this early (pre-impulsive superhot LT) phase, whereas the
  LT densities increase to a peak value of (3-4) × 10<SUP>11</SUP>
  cm<SUP>-3</SUP>.<BR /> Conclusions: .Modeling of a collapsing magnetic
  trap embedded in a standard 2D magnetic reconnection model can reproduce
  the key observational findings in case that the observed emission is
  thermal bremsstrahlung from the hot LT plasma. This agrees with the
  evaluated RHESSI spectra for this flare.

---------------------------------------------------------
Title: Hemispheric Sunspot Numbers 1945--2004: data merging from
    two observatories
Authors: Temmer, M.; Rybák, J.; Bendík, P.; Veronig, A.; Vogler,
   F.; Pötzi, W.; Otruba, W.; Hanslmeier, A.
2006CEAB...30...65T    Altcode:
  For the time span 1945--2004 from daily sunspot drawings northern
  and southern relative sunspot numbers are extracted using drawings
  provided by Kanzelhöhe Solar Observatory, Austria, and Skalnaté Pleso
  Observatory, Slovak Republic. The derived data will be used to improve
  and extend an already existing catalogue of hemispheric sunspot numbers
  (Temmer et al., 2002). Since northern and southern solar hemispheres
  do not evolve in phase during the cycle, hemispheric data are very
  important for activity studies. In the present paper the compilation
  of the data for the period 1945--2004 is described. Furthermore as a
  quality check of the derived hemispheric data a regression analysis and
  the comparison to the international hemispheric sunspot numbers from
  the Sunspot Index Data Center for the time span 1992--2004 is presented.

---------------------------------------------------------
Title: Periodical patterns in major flare occurrence and their
    relation to magnetically complex active regions
Authors: Temmer, M.; Veronig, A.; Rybák, J.; Brajša, R.; Hanslmeier,
   A.
2006AdSpR..38..886T    Altcode:
  A periodical occurrence rate of major solar flares (observed in hard
  X-rays) of ∼24 days (synodic) was first reported by Bai (1987)
  [Bai, T. Distribution of flares on the sun superactive regions and
  active zones of 1980 1985. ApJ 314, 795 807, 1987] for the years 1980
  1985. Here, we report a significant relation between the appearance of
  the 24-day period in major Hα flares and magnetically complex sunspot
  groups (i.e., including a γ and/or δ configuration). From synoptic
  maps of magnetograms (NSO/KP) patterns in the magnetic flux evolution
  are traced which might be the cause of the 24-day period observed in
  flare activity.

---------------------------------------------------------
Title: X-Ray Sources and Magnetic Reconnection in AN X-Class Flare
Authors: Veronig, A. M.; Vršnak, B.; Karlický, M.; Temmer, M.;
   Magdalenić, J.; Dennis, B. R.; Otruba, W.; Pötzi, W.
2005ESASP.600E..32V    Altcode: 2005ESPM...11...32V; 2005dysu.confE..32V
  No abstract at ADS

---------------------------------------------------------
Title: Hemispheric Sunspot Numbers RN and RS from 1945-2004: Extended
    and Improved Catalogue
Authors: Temmer, M.; Rybák, J.; Veronig, A.; Bendík, P.; Vogler,
   F.; Pötzi, W.; Otruba, W.; Hanslmeier, A.
2005ESASP.600E..52T    Altcode: 2005ESPM...11...52T; 2005dysu.confE..52T
  No abstract at ADS

---------------------------------------------------------
Title: Wave Phenomena Associated with the X3.8 Flare/cme of
    17-JAN-2005
Authors: Temmer, M.; Veronig, A.; Vršnak, B.; Thalmann, J.;
   Hanslmeier, A.
2005ESASP.600E.144T    Altcode: 2005ESPM...11..144T; 2005dysu.confE.144T
  No abstract at ADS

---------------------------------------------------------
Title: VizieR Online Data Catalog: Hemispheric Sunspot Numbers
    1945-2004 (Temmer+, 2006)
Authors: Temmer, M.; Rybak, J.; Bendik, P.; Veronig, A.; Vogler, F.;
   Otruba, W.; Poetzi, W.; Hanslmeier, A.
2005yCat..34470735T    Altcode:
  From sunspot drawings provided by the Kanzelhoehe Solar Observatory,
  Austria, and the Skalnate Pleso Observatory, Slovak Republic,
  a data catalogue of hemispheric Sunspot Numbers covering the time
  span 1945-2004 is extracted. The validated catalogue includes daily,
  monthly-mean and smoothed-monthly relative sunspot numbers for the
  northern and southern hemispheres separately and is available for
  scientific use. Based on this data set an analysis concerning the
  North-South asymmetry is made within this paper. <P />(2 data files).

---------------------------------------------------------
Title: Spatial Distribution and North-South Asymmetry of Coronal
    Bright Points from Mid-1998 to Mid-1999
Authors: Brajša, R.; Wöhl, H.; Vršnak, B.; Rušdjak, V.; Clette,
   F.; Hochedez, J. -F.; Verbanac, G.; Temmer, M.
2005SoPh..231...29B    Altcode:
  Full-disc full-resolution (FDFR) solar images obtained with the Extreme
  Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric
  Observatory (SOHO) were used to analyse the centre-to-limb function and
  latitudinal distribution of coronal bright points. The results obtained
  with the interactive and the automatic method, as well as for three
  subtypes of coronal bright points for the time period 4 June 1998 to 22
  May 1999 are presented and compared. An indication of a two-component
  latitudinal distribution of coronal bright points was found. The
  central latitude of coronal bright points traced with the interactive
  method lies between 10<SUP>∘</SUP> and 20<SUP>∘</SUP>. This is
  closer to the equator than the average latitude of sunspots in the
  same period. Possible implications for the interpretation of the
  solar differential rotation are discussed. In the appendix, possible
  differences between the two solar hemispheres are analysed. More coronal
  bright points were present in the southern solar hemisphere than in
  the northern one. This asymmetry is statistically significant for the
  interactive method and not for the automatic method. The visibility
  function is symmetrical around the central meridian.

---------------------------------------------------------
Title: Broadband Metric-Range Radio Emission Associated with a
    Moreton/EIT Wave
Authors: Vršnak, B.; Magdalenić, J.; Temmer, M.; Veronig, A.;
   Warmuth, A.; Mann, G.; Aurass, H.; Otruba, W.
2005ApJ...625L..67V    Altcode:
  We present the evolution and kinematics of a broadband radio source
  that propagated collaterally with an Hα/EIT wave, linking it with the
  type II burst that was excited higher up in the corona. The NRH wave
  emission extended from the frequency f~327 to f&lt;151 MHz and was
  considerably weaker than the flare-related type IV burst. The emission
  centroid propagated at a height of 0-200 Mm above the solar limb and
  was intensified when the disturbance passed over enhanced coronal
  structures. We put forward the ad hoc hypothesis that the NRH wave
  signature is optically thin gyrosynchrotron emission excited by the
  passage of the coronal MHD fast-mode shock. The identification of radio
  emission associated with the coronal wave front is important since it
  offers us new diagnostic information that could provide us with better
  insight into the physical conditions in the disturbance itself.

---------------------------------------------------------
Title: What causes the 24-day period observed in solar flares?
Authors: Temmer, M.; Rybák, J.; Veronig, A.; Hanslmeier, A.
2005A&A...433..707T    Altcode:
  Previous studies report a 24-day (synodic) period in the occurrence
  rate of solar flares for each of the solar cycles studied, Nos. 19-22
  (Bai 1987, ApJ, 314, 795; Temmer et al. 2004, Sol. Phys. 221,
  325). Here we study the 24-day period in the solar flare occurrence
  for solar cycles 21 and 22 by means of wavelet power spectra together
  with the solar flare locations in synoptic magnetic maps. We find
  that the 24-day peak revealed in the power spectra is just the
  result of a particular statistical clumping of data points, most
  probably caused by a characteristic longitudinal separation of about
  +40<SUP>circ</SUP> to +50<SUP>circ</SUP> of activity complexes in
  successive Carrington rotations. These complexes appear as parallel,
  diverging or converging branches in the synoptic magnetic maps and
  are particularly flare-productive.

---------------------------------------------------------
Title: The Two Complexes of Activity Observed in the Northern
    Hemisphere during 1982 and the 24-Day Periodicity of Flare Occurrence
Authors: Ruždjak, V.; Ruždjak, D.; Brajša, R.; Temmer, M.;
   Hanslmeier, A.
2005HvaOB..29..117R    Altcode:
  Daily numbers of solar Hα flares of importance classes ≥ 1 for
  the northern solar hemisphere in 1982 are studied applying wavelet
  power spectra (WPS). Special attention is paid to the occurrence of a
  24-day period in the WPS. The wavelet power spectra method is combined
  with synoptic maps of the magnetic fields. Separately, flare indices
  of two activity complexes mainly contributing to flare occrrence in
  this period are examined. It is found that the detected 24-day signal
  in the WPS is mainly a consequence of the presence of the two flare
  activity complexes separated by about 45° in longitude during several
  succesive Carrington rotations.

---------------------------------------------------------
Title: Properties of Type IV Radio Bursts with Periodical Fine
    Structures
Authors: Magdalenić, J.; Vršnak, B.; Zlobec, P.; Messerotti, M.;
   Temmer, M.
2005ASSL..320..259M    Altcode: 2005smp..conf..259M
  No abstract at ADS

---------------------------------------------------------
Title: On the Relation Between the Coronal Free Energy and Solar
    Flare Occurrence
Authors: Temmer, M.; Veronig, A.; Hanslmeier, A.
2005HvaOB..29..109T    Altcode:
  A significant delay with a 22-year modulation in solar flare occurrence
  was found by te{temmer03solph} with respect to the solar cycle defined
  on the basis of the relative sunspot number. These observational results
  were modelled by te{litvi03} through a time-dependent balance of the
  magnetic free energy in the solar corona. The free magnetic energy is
  assumed to be depleted mainly by flares and lags behind the variation
  of the energy supply (emerging magnetic flux - proxy: relative sunspot
  numbers) to this system. For solar cycles 21 and 23, in accordance with
  the delay obtained for flare rates, the rate of sunspot group numbers
  lags behind the solar cycle maximum. Theses findings suggest that
  the energy supply itself is delayed, most prominent in odd numbered
  solar cycles which subsequently causes the delay observed for flare
  and sunspot group occurrences.

---------------------------------------------------------
Title: Loop-Top Altitude Decrease in an X-Class Flare
Authors: Veronig, A.; Vršnak, B.; Karlický, M.; Temmer, M.;
   Magdalenić, J.; Dennis, B. R.; Otruba, W.; Pötzi, W.
2005HvaOB..29..127V    Altcode:
  We study RHESSI X-ray source motions in the X3.9 flare of 2003 November
  3. Particular attention is drawn to the apparent altitude decrease
  of a distinct loop-top (LT) source at the early flare phase before
  then changing to the commonly observed upward expansion of the flare
  loop system. We obtain that the downward motion is more pronounced
  at higher X-ray energies (peak values up to 50 km s^{-1}) consistent
  with recent findings by Sui et al. (2004). RHESSI spectra indicate
  that the emission process in the LT source is thermal bremsstrahlung
  from a super hot plasma (∼40 MK) with high densities increasing from
  ∼10^{10} cm^{-3} early in the flare to several times 10^{11} cm^{-3}
  at the end of RHESSI observations.

---------------------------------------------------------
Title: On the 24- and 155-Day Periodicity Observed in Solar Hα Flares
Authors: Temmer, M.; Veronig, A.; Hanslmeier, A.
2005ASSL..320..211T    Altcode: 2005smp..conf..211T
  No abstract at ADS

---------------------------------------------------------
Title: On the 24-day period observed in solar flare occurrence
Authors: Temmer, M.; Veronig, A.; Rybák, J.; Brajša, R.; Hanslmeier,
   A.
2004SoPh..221..325T    Altcode:
  Time series of daily numbers of solar Hα flares from 1955 to
  1997 are studied by means of wavelet power spectra with regard to
  predominant periods in the range of ∼ 24 days (synodic). A 24-day
  period was first reported by Bai (1987) for the occurrence rate of
  hard X-ray flares during 1980-1985. Considering the northern and
  southern hemisphere separately, we find that the 24-day period is not
  an isolated phenomenon but occurs in each of the four solar cycles
  investigated (No. 19-22). The 24-day period can be established also
  in the occurrence rate of subflares but occurs more prominently in
  major flares (importance classes ≥ 1). A comparative analysis of
  magnetically classified active regions subdivided into magnetically
  complex (i.e., including a γ and/or δ configuration) and non-complex
  (α, β) reveals a significant relation between the appearance of
  the 24-day period in Hα flares and magnetically complex sunspot
  groups, whereas it cannot be established for non-complex groups. It is
  suggested that the 24-day period in solar flare occurrence is related
  to a periodic emergence of new magnetic flux rather than to the surface
  rotation of sunspots.

---------------------------------------------------------
Title: Merging two data sets of hemispheric Sunspot Numbers
Authors: Rybák, J.; Bendík, P.; Temmer, M.; Veronig, A.; Hanslmeier,
   A.
2004HvaOB..28...63R    Altcode:
  First results on merging two data sets of hemispheric sunspot numbers
  -- from the Kanzelhöhe Solar Observatory and the Skalnaté Pleso
  Observatory -- for the time span 1977 -- 1978 are presented. A total
  coverage of 86% was reached for the merged data set. In order to have
  a homogeneous time series, the daily sunspot numbers for the full disk
  from both observing stations were normalized to the international
  relative sunspot number of the day. The derived hemispheric sunspot
  numbers from Kanzelhöhe and Skalnaté Pleso Observatory %compared
  for 290 common observing show very high correlations (r ≳ 0.95), and
  the estimated data noise yields significant differences only for small
  values of sunspot numbers. These outcomes demonstrate the high potential
  of the applied merging procedure, and are the basis for an ongoing
  project to derive hemispheric sunspot numbers back to the year 1945
  using sunspot drawings from Kanzelhöhe and Skalnaté Pleso Observatory.

---------------------------------------------------------
Title: Importance of magnetically complex active regions on solar
    flare occurrence
Authors: Temmer, M.; Veronig, A.; Rybák, J.; Brajša, R.; Hanslmeier,
   A.
2004HvaOB..28...95T    Altcode:
  Daily numbers of solar Hα flares from 1955 to 1997 and daily numbers
  of magnetically classified active regions for the time span 1964--1997
  are studied applying wavelet power spectra. The occurrence of dominant
  periods in the range of ∼24 days (synodic) is investigated considering
  the northern and southern hemisphere separately. From the flare events
  it is revealed that the 24-day period occurs in each of the four solar
  cycles investigated (no. 19--22). The 24-day period can be established
  also in the occurrence rate of subflares but occurs more prominently
  in major flares (importance classes ≥1). Magnetically complex active
  regions, i.e. including a γ and/or δ configuration, show the 24-day
  period closely related to those found for major Hα flares, whereas
  it cannot be established for non-complex α, β groups.

---------------------------------------------------------
Title: Periodical patterns in major flare occurrence and their
    relation to magnetically complex active regions
Authors: Temmer, M.; Veronig, A.; Rybak, J.; Brajsa, R.; Hanslmeier, A.
2004cosp...35.1395T    Altcode: 2004cosp.meet.1395T
  A periodical occurrence rate of solar major flares (observed in
  hard X-rays) of about 24 days (synodic) was first reported by Bai
  (1987) for the years 1980--1985. Its origin is still far from being
  understood. Applying wavelet analyses for daily numbers of Hα flare
  events covering almost four entire solar cycles (no. 19--22) reveals a
  24-day period in each of the cycles studied. This can be established
  primarily in the occurrence rate of major flares but is also seen
  in subflares. Since large flares occur preferentially in association
  with active regions of complex magnetic configuration a comparative
  study of magnetically classified active regions, subdivided into
  magnetically complex (i.e. including a γ and/or δ configuration)
  and non-complex (α, β) was performed. A significant relation
  between the appearance of the 24-day period in major Hα flares and
  magnetically complex sunspot groups is found, whereas it cannot be
  established for non-complex groups. From solar rotation studies based
  on tracing sunspots practically no siderial rotation velocities as high
  as 16 deg/day (which corresponds to a synodic period of ∼24 days)
  are reported. Thus the cause of the 24-day period is very likely not
  related to solar surface rotation. Alternatively it might be due to
  periodical patterns in magnetic flux emergence which is an important
  driver of flare eruptions. We test this hypothesis by investigating
  synoptic maps of magnetograms (National Solar Observatory/Kitt Peak)
  for selected time ranges in which the 24-day period is revealed for
  both flares and magnetically complex active regions.

---------------------------------------------------------
Title: The solar soft X-ray background flux and its relation to
    flare occurrence
Authors: Veronig, Astrid M.; Temmer, Manuela; Hanslmeier, Arnold
2004SoPh..219..125V    Altcode:
  The soft X-ray background flux (XBF) based on GOES 1-8 Å measurements
  for the period 1975-2003 is studied. There is strong evidence that
  in the XBF the flare contribution is not eliminated but the XBF is
  dominated by flare and post-flare emission of intense events. The
  significant delay (∼ 2 years) of the peak of the X-ray background
  flux with regard to sunspot numbers reported for cycle 21 recurs in
  the present cycle 23. The relation between monthly XBF and sunspot
  numbers can be well represented by a power law. For cycles 21 and 23
  the derived fit values are the same within the uncertainties, whereas
  the values for cycle 22 are significantly different. It is suggested
  that the lag of the XBF in cycles 21 and 23 is a secondary effect
  related to the substantial contribution of energetic flares which is
  not fully subtracted out by the actual XBF definition.

---------------------------------------------------------
Title: On rotational patterns of the solar magnetic field
Authors: Temmer, M.; Veronig, A.; Rybák, J.; Hanslmeier, A.
2003ESASP.535..157T    Altcode: 2003iscs.symp..157T
  Solar magnetic field variations (NSO/Kitt Peak data) through solar cycle
  23 with respect to rotational modulations are analyzed. A comparative
  study to solar cycles 21 and 22 is performed. The results are compared
  to the rotational behavior of activity tracers like sunspots and solar
  Hα flares. Periodical occurrences of flares often match the 27-day
  solar rotation due to recurrent stable sunspot groups and complexes
  of activity which likely produce more flare events than short-living
  small sunspots. However, periods with strong deviations from the 27-day
  period are obtained for higher energetic flares. The solar magnetic
  field is found to vary on similar time scales, which suggests a close
  relation to the occurrence of strong flare events.

---------------------------------------------------------
Title: Solar cycle variations of the soft X-ray background flux and
    its relation to flare occurrence
Authors: Veronig, A.; Temmer, M.; Hanslmeier, A.
2003ESASP.535..259V    Altcode: 2003iscs.symp..259V
  The X-ray background flux (XBF) based on GOES 1-8 Å measurements for
  the period 1975-2000 is studied. We come to the conclusion that in the
  XBF the flare contribution is not eliminated but the XBF is dominated
  by flare and post-flare emission of intense events. Furthermore, we
  suggest that the characteristic lag of the X-ray background flux with
  regard to Sunspot Numbers reported for cycle 21 is a secondary effect
  related to the substantial contribution of large flares to the XBF.

---------------------------------------------------------
Title: Radio signatures of fast oscillatory phenomena in the solar
    corona
Authors: Magdalenic, Jasmina; Zlobec, P.; Vršnak, B.; Messerotti,
   M.; Aurass, H.; Temmer, M.
2003ESASP.535..619M    Altcode: 2003iscs.symp..619M
  During type IV solar radio bursts different types of periodic fine
  structures (PFSs) are frequently observed, which can be interpreted
  as radio signatures of fast oscillatory phenomena in the coronal
  plasma. We analyze a large set of type IV bursts containing PFSs,
  recorded with high time resolution at single frequencies in the
  metric and decimetric bands. Focusing on the association with flares
  and flare-like phenomena we found: PFSs can be found in about 50% of
  type IV bursts characterized by fine structures; 10% of PFS-containing
  events are weak/short type IV-like radio bursts that occur in absence
  of any flare-like activity. In the weakest events the whole radio
  burst was in fact just one short PFS-episode recorded at only one
  observing frequency; In flare associated events we found two distinct
  classes of PFSs - impulsive phase and decay phase related PFSs; yet,
  no statistically significant difference in the characteristic periods
  and amplitudes is found between the two classes; PFS-rich radio events
  are characterized by large SXR and radio peak fluxes - neither one
  of the weak type IV bursts was PFS-rich. The opposite is not true:
  mainly powerful bursts are PFS-poor.

---------------------------------------------------------
Title: Does solar flare activity lag behind sunspot activity?
Authors: Temmer, M.; Veronig, A.; Hanslmeier, A.
2003SoPh..215..111T    Altcode:
  Recently, Wheatland and Litvinenko (2001) have suggested that over the
  solar cycle both the flaring rate and the magnetic free energy in the
  corona lag behind the energy supply to the system. To test this model
  result, we analyzed the evolution of solar flare occurrence with regard
  to sunspot numbers (as well as sunspot areas), using Hα flare data
  available for the period 1955-2002, and soft X-ray flare data (GOES
  1-8 Å) for the period 1976-2002. For solar cycles 19, 21, and 23,
  we find a characteristic time lag between flare activity and sunspot
  activity in the range 10≲τ≲15 months, consistent with the model
  predictions by Wheatland and Litvinenko (2001). The phenomenon turns
  out to be more prominent for highly energetic flares. The investigation
  of solar activity separately for the northern and southern hemisphere
  allows us to exclude any bias due to overlapping effects from the
  activity of both hemispheres and confirms the dynamic relevance of the
  delay phenomenon. Yet, no characteristic time lag τ&gt;0 is found for
  solar cycles 20 and 22. The finding that in odd-numbered cycles flare
  activity is statistically delayed with respect to sunspot activity,
  while in even-numbered cycles it is not, suggests a connection to the
  22-year magnetic cycle of the Sun. Further insight into the connection
  to the 22-year magnetic cycle could possibly be gained when a 22-year
  variation in the energy supply rate is taken into account in the
  Wheatland and Litvinenko (2001) model. The existence of a 22-year
  modulation in the energy supply rate is suggested by the empirical
  Gnevyshev - Ohl rule, and might be caused by a relic solar field.

---------------------------------------------------------
Title: Rotational modulation of northern and southern activity tracers
Authors: Temmer, M.; Veronig, A.; Rybák, J.; Hanslmeier, A.
2003HvaOB..27...59T    Altcode:
  We study solar activity phenomena, Hα flares and sunspots, with respect
  to their periodical occurrence related to the solar rotation. The
  analysis is carried out separately for the northern and the southern
  hemisphere. Furthermore, flare occurrences are studied with respect
  to different importance classes, and the results are compared to
  the predominant periods derived from Sunspot Numbers. Significant
  asymmetries are obtained between the northern and southern activity for
  both Sunspot Numbers and flare occurrences. Differences between Sunspot
  Numbers and flares result particularly when only higher energetic
  flares are considered. A 24-day period is found for large flare events
  in both hemispheres which is not detected in Sunspot Numbers.

---------------------------------------------------------
Title: Catalogue of hemispheric sunspot numbers R<SUB>N</SUB> and
R<SUB>S</SUB>: 1975 - 2000
Authors: Temmer, M.; Veronig, A.; Hanslmeier, A.
2002ESASP.506..855T    Altcode: 2002svco.conf..855T; 2002ESPM...10..855T
  Sunspot drawings are provided on a regular basis at the Kanzelhöhe
  Solar Obseratory, Austria, and the derived relative sunspot numbers
  are reported to the Sunspot Index Data Center in Brussels. From the
  daily sunspot drawings, we derived the northern, R<SUB>n</SUB>,
  and southern, R<SUB>s</SUB>, relative sunspot numbers for the
  time span 1975-2000. In order to accord with the International
  Sunspot Numbers R<SUB>i</SUB>, the R<SUB>n</SUB> and R<SUB>s</SUB>
  have been normalized to the R<SUB>i</SUB>, which ensures that the
  relation R<SUB>n</SUB>+R<SUB>s</SUB> = R<SUB>i</SUB> is complied. For
  validation, the derived R<SUB>n</SUB> and R<SUB>s</SUB> are compared
  to the international northern and southern relative sunspot numbers,
  which are available since 1992. The regression analysis performed for
  the period 1992-2000 reveals good agreement with the International
  hemispheric Sunspot Numbers. The monthly mean and the smoothed monthly
  mean hemispheric Sunspot Numbers are compiled to a catalogue. In
  addition, the daily hemispheric Sunspot Numbers are made available
  via Internet.

---------------------------------------------------------
Title: Cycle dependence of hemispheric activity
Authors: Temmer, M.; Veronig, A.; Rybák, J.; Hanslmeier, A.
2002ESASP.506..859T    Altcode: 2002ESPM...10..859T; 2002svco.conf..859T
  Data of daily hemispheric Sunspot Numbers are analyzed including the
  time span 1975-2001. The study of north-south asymmetries concerning
  solar activity and rotational behaviors is in particular relevant,
  as it is related to the solar dynamo and the generation of magnetic
  fields. As diagnostic tools we use wavelets and autocorrelation
  functions in combination with statistical significance tests that are
  applied separately to the northern and southern hemisphere. Pronounced
  differences between the northern and southern rotational periods
  are obtained. The northern hemisphere shows a rigid rotation of ~27
  days which can be followed up to ~15 periods in the autocorrelation
  function. The signal of the southern hemisphere is strongly attenuated
  after 3 recurrences showing variable periods in the range ~26-28.5
  days. The presence of these periods is not permanent during a cycle
  suggesting activity pulses in each hemisphere. For the northern
  hemisphere strong relations to the motions of deeper lying convective
  structures building up long-living 'active zones' are suggested.

---------------------------------------------------------
Title: The Neupert effect and the electron-beam-driven evaporation
    model
Authors: Veronig, A.; Vršnak, B.; Dennis, B. R.; Temmer, M.;
   Hanslmeier, A.; Magdalenić, J.
2002ESASP.506..367V    Altcode: 2002svco.conf..367V; 2002ESPM...10..367V
  Based on a sample of ~1100 solar flares observed simultaneously in
  hard and soft X-rays, we performed a statistical analysis of the
  Neupert effect. For a subset of ~500 events, supplementary Hα flare
  data were considered. The timing behavior of &gt;50% of the events
  is consistent with the Neupert effect. A high correlation between
  the soft X-ray peak flux and the hard X-ray fluence is obtained,
  being indicative of electron-beam-driven evaporation. However, about
  one fourth of the events (predominantly weak flares) reveal strong
  deviations from the predicted timing, with a prolonged increase of
  the thermal emission beyond the end of the hard X-rays. These findings
  suggest that electron-beam-driven evaporation plays an important role
  in solar flares. Yet, in a significant fraction of events there is also
  evidence for an additional energy transport mechanism from the energy
  release site other than electron beams, presumably thermal conduction.

---------------------------------------------------------
Title: The Neupert effect in solar flares and implications for
    coronal heating
Authors: Veronig, A.; Vrsnak, B.; Dennis, B. R.; Temmer, M.;
   Hanslmeier, A.; Magdalenić, J.
2002ESASP.505..599V    Altcode: 2002solm.conf..599V; 2002IAUCo.188..599V; 2002astro.ph..8089V
  Based on simultaneous observations of solar flares in hard and soft
  X-rays we studied several aspects of the Neupert effect. About half of
  1114 analyzed events show a timing behavior consistent with the Neupert
  effect. For these events, a high correlation between the soft X-ray
  peak flux and the hard X-ray fluence is obtained, being indicative of
  electron-beam-driven evaporation. However, for about one fourth of the
  events there is strong evidence for an additional heating agent other
  than electron beams. We discuss the relevance of these findings with
  respect to Parker's idea of coronal heating by nanoflares.

---------------------------------------------------------
Title: Hemispheric asymmetry of solar activity phenomena: north-south
    excesses rotational periods and their links to the magnetic field
Authors: Temmer, M.; Veronig, A.; Hanslmeier, A.
2002ESASP.505..587T    Altcode: 2002solm.conf..587T; 2002IAUCo.188..587T
  We present a cycle dependent analysis of various solar activity
  phenomena, namely Sunspot Numbers and Hα flares, including the
  time range 1975-2000. The data are studied on a statistical basis
  with relation to their spatial distribution, significance of the
  north-south asymmetry and rotational periods. For the considered time
  span we obtain significant values of north-south asymmetries. For the
  northern hemisphere the significant excesses are revealed during the
  increasing and maximum phase of a solar cycle whereas a southern excess
  dominates near the end of a cycle. Furthermore, we obtain differences
  in rotational periods and activity gaps between both hemispheres that
  suggest an independent evolution in hemispheric activity for these
  indices. Hence, a weak interdependence of the magnetic field system
  originating in the two hemispheres is suggested. Additionally we find
  differences in the dominant rotational periods of photospheric and
  chromospheric tracers.

---------------------------------------------------------
Title: Investigation of the Neupert effect in solar
    flares. I. Statistical properties and the evaporation model
Authors: Veronig, A.; Vršnak, B.; Dennis, B. R.; Temmer, M.;
   Hanslmeier, A.; Magdalenić, J.
2002A&A...392..699V    Altcode: 2002astro.ph..7217V
  Based on a sample of 1114 flares observed simultaneously in hard X-rays
  (HXR) by the BATSE instrument and in soft X-rays (SXR) by GOES, we
  studied several aspects of the Neupert effect and its interpretation
  in the frame of the electron-beam-driven evaporation model. In
  particular, we investigated the time differences (Delta t) between
  the maximum of the SXR emission and the end of the HXR emission,
  which are expected to occur at almost the same time. Furthermore,
  we performed a detailed analysis of the SXR peak flux - HXR fluence
  relationship for the complete set of events, as well as separately for
  subsets of events which are likely compatible/incompatible with the
  timing expectations of the Neupert effect. The distribution of the time
  differences reveals a pronounced peak at Delta t = 0. About half of the
  events show a timing behavior which can be considered to be consistent
  with the expectations from the Neupert effect. For these events, a high
  correlation between the SXR peak flux and the HXR fluence is obtained,
  indicative of electron-beam-driven evaporation. However, there is also
  a significant fraction of flares (about one fourth), which show strong
  deviations from Delta t = 0, with a prolonged increase of the SXR
  emission distinctly beyond the end of the HXR emission. These results
  suggest that electron-beam-driven evaporation plays an important role
  in solar flares. Yet, in a significant fraction of events, there is
  also clear evidence for the presence of an additional energy transport
  mechanism other than nonthermal electron beams, where the relative
  contribution is found to vary with the flare importance.

---------------------------------------------------------
Title: Hemispheric Sunspot Numbers R<SUB>n</SUB> and R<SUB>s</SUB>:
    Catalogue and N-S asymmetry analysis
Authors: Temmer, M.; Veronig, A.; Hanslmeier, A.
2002A&A...390..707T    Altcode: 2002astro.ph..8436T
  Sunspot drawings are provided on a regular basis at the Kanzelhöhe
  Solar Observatory, Austria, and the derived relative sunspot numbers
  are reported to the Sunspot Index Data Center in Brussels. From the
  daily sunspot drawings, we derived the northern, R<SUB>n</SUB>,
  and southern, R<SUB>s</SUB>, relative sunspot numbers for the
  time span 1975-2000. In order to accord with the International
  Sunspot Numbers R<SUB>i</SUB>, the R<SUB>n</SUB> and R<SUB>s</SUB>
  have been normalized to the R<SUB>i</SUB>, which ensures that the
  relation R<SUB>n</SUB>+R<SUB>s</SUB>=R<SUB>i</SUB> is fulfilled. For
  validation, the derived R<SUB>n</SUB> and R<SUB>s</SUB> are compared
  to the international northern and southern relative sunspot numbers,
  which are available from 1992. The regression analysis performed for
  the period 1992-2000 reveals good agreement with the International
  hemispheric Sunspot Numbers. The monthly mean and the smoothed
  monthly mean hemispheric Sunspot Numbers are compiled into a
  catalogue. Based on the derived hemispheric Sunspot Numbers,
  we study the significance of N-S asymmetries and the rotational
  behavior separately for both hemispheres. We obtain that ~ 60% of the
  monthly N-S asymmetries are significant at a 95% level, whereas the
  relative contributions of the northern and southern hemisphere are
  different for different cycles. From the analysis of power spectra
  and autocorrelation functions, we derive a rigid rotation with ~
  27 days for the northern hemisphere, which can be followed for up
  to 15 periods. Contrary to that, the southern hemisphere reveals a
  dominant period of ~ 28 days, whereas the autocorrelation is strongly
  attenuated after 3 periods. These findings suggest that the activity
  of the northern hemisphere is dominated by an active zone, whereas
  the southern activity is mainly dominated by individual long-lived
  sunspot groups. The catalogue is available in electronic form at the
  CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
  http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/390/707

---------------------------------------------------------
Title: Relative timing of solar flares observed at different
    wavelengths
Authors: Veronig, A.; Vršnak, B.; Temmer, M.; Hanslmeier, A.
2002SoPh..208..297V    Altcode: 2002astro.ph..8088V
  The timing of 503 solar flares observed simultaneously in hard X-rays,
  soft X-rays and Hα is analyzed. We investigated the start and the peak
  time differences in different wavelengths, as well as the differences
  between the end of the hard X-ray emission and the maximum of the
  soft X-ray and Hα emission. In more than 90% of the analyzed events,
  a thermal pre-heating seen in soft X-rays is present prior to the
  impulsive flare phase. On average, the soft X-ray emission starts 3 min
  before the hard X-ray and the Hα emission. No correlation between the
  duration of the pre-heating phase and the importance of the subsequent
  flare is found. Furthermore, the duration of the pre-heating phase
  does not differ for impulsive and gradual flares. For at least half of
  the events, the end of the non-thermal emission coincides well with
  the maximum of the thermal emission, consistent with the beam-driven
  evaporation model. On the other hand, for ∼ 25% of the events there
  is strong evidence for prolonged evaporation beyond the end of the
  hard X-rays. For these events, the presence of an additional energy
  transport mechanism, most probably thermal conduction, seems to play
  an important role.

---------------------------------------------------------
Title: VizieR Online Data Catalog: Hemispheric Sunspot Numbers
    1975-2000 (Temmer+, 2002)
Authors: Temmer, M.; Veronig, A.; Hanslmeier, A.
2002yCat..33900707T    Altcode:
  Hemispheric sunspot numbers including the time span from 1975-2000 are
  presented. The Sunspot Numbers are calculated from sunspot drawings
  made at the Kanzelhoehe Solar Observatory (KSO), Austria. The counted
  northern and southern Sunspot Numbers are normalized and multiplied
  with the International Sunspot Numbers taken from SIDC for matching
  days in order to provide the data within an international usage. Days
  without observation by KSO (about 27 percent) were reconstructed
  applying a linear interpolation method. As validation of the data,
  regression methods and a cross-correlation analysis are made with
  hemispheric Sunspot Numbers from SIDC for the available time span
  1992-2000 obtaining very good agreements. The results are given in
  monthly mean and smoothed monthly mean Sunspot Numbers. Based on this
  data set an analysis concerning the North-South asymmetry is made in
  the paper. (1 data file).

---------------------------------------------------------
Title: Soft X-ray flares for the period 1975-2000
Authors: Temmer, M.; Veronig, A.; Hanslmeier, A.; Otruba, W.;
   Messerotti, M.
2002ESASP.477..175T    Altcode: 2002scsw.conf..175T
  Statistical aspects of solar soft X-ray (SXR) flares for the period
  September 1975 to December 2000 are investigated. In particular,
  we analyzed the spatial distribution of SXR flares with regard to
  the solar hemispheres, i.e. N-S and E-W asymmetries, as well as the
  occurrence of SXR flares in the course of the solar cycle. We obtain
  that the occurrence rate of SXR flares is delayed in relation to the
  Sunspot Numbers which can be interpreted as an interaction between
  the northern and southern hemisphere activity.

---------------------------------------------------------
Title: Temporal characteristics of solar soft X-ray and Hα flares
Authors: Veronig, A.; Temmer, M.; Hanslmeier, A.; Messerotti, M.;
   Otruba, W.; Moretti, P. F.
2002ESASP.477..187V    Altcode: 2002scsw.conf..187V
  Temporal aspects of solar soft X-ray and Hα flares for the period
  1997-2000 are investigated. For the considered time span about 8400
  SXR and 11400 Hα flares are reported in the SGD. Related flares
  observed in Hα as well as in SXR are identified amounting to about
  2100 events. Correlations among corresponding SXR and Hα events are
  analyzed and their relative timing is investigated. From the timing
  analysis we infer that for most of the events (84%) the start of the
  Hα emission is delayed with respect to the SXR emission. On average,
  the Hα flare starts 3 minutes after the SXR flare. The peaks occur
  preferentially simultaneously with a slight tendency that the Hα peak
  precedes the SXR peak.

---------------------------------------------------------
Title: Temporal aspects and frequency distributions of solar soft
    X-ray flares
Authors: Veronig, A.; Temmer, M.; Hanslmeier, A.; Otruba, W.;
   Messerotti, M.
2002A&A...382.1070V    Altcode: 2002astro.ph..7234V
  A statistical analysis of almost 50 000 soft X-ray (SXR) flares observed
  by GOES during the period 1976-2000 is presented. On the basis of
  this extensive data set, statistics on temporal properties of soft
  X-ray flares, such as duration, rise and decay times with regard to
  the SXR flare classes is presented. Correlations among distinct flare
  parameters, i.e. SXR peak flux, fluence and characteristic times,
  and frequency distributions of flare occurrence as function of the
  peak flux, the fluence and the duration are derived. We discuss the
  results of the analysis with respect to statistical flare models, the
  idea of coronal heating by nanoflares, and elaborate on implications
  of the obtained results on the Neupert effect in solar flares.

---------------------------------------------------------
Title: Frequency Distributions of solar Flares
Authors: Veronig, A.; Temmer, M.; Hanslmeier, A.
2002HvaOB..26....7V    Altcode:
  Flare frequency distributions as function of the soft X-ray peak flux
  and fluence are investigated. We analyse GOES 1--8 Å data for the
  period 1986--2000. The results are discussed with respect to avalanche
  flare models and the hypothesis of coronal heating by nanoflares.

---------------------------------------------------------
Title: Statistical analysis of solar Hα flares
Authors: Temmer, M.; Veronig, A.; Hanslmeier, A.; Otruba, W.;
   Messerotti, M.
2001A&A...375.1049T    Altcode: 2002astro.ph..7239T
  A statistical analysis of a large data set of Hα flares comprising
  almost 100 000 single events that occurred during the period
  January 1975 to December 1999 is presented. We analyzed the flares
  evolution steps, i.e. duration, rise times, decay times and event
  asymmetries. Moreover, these parameters characterizing the temporal
  behavior of flares, as well as the spatial distribution on the solar
  disk, i.e. N-S and E-W asymmetries, are analyzed in terms of their
  dependency on the solar cycle. The main results are: 1) The duration,
  rise and decay times increase with increasing importance class. The
  increase is more pronounced for the decay times than for the rise
  times. The same relation is valid with regard to the brightness
  classes but in a weaker manner. 2) The event asymmetry indices,
  which characterize the proportion of the decay to the rise time of
  an event, are predominantly positive (~90%). For about 50% of the
  events the decay time is even more than 4 times as long as the rise
  time. 3) The event asymmetries increase with the importance class. 4)
  The flare duration and decay times vary in phase with the solar cycle;
  the rise times do not. 5) The event asymmetries do not reveal a distinct
  correlation with the solar cycle. However, they drop during times of
  solar minima, which can be explained by the shorter decay times found
  during minimum activity. 6) There exists a significant N-S asymmetry
  over longer periods, and the dominance of one hemisphere over the
  other can persist for more than one cycle. 7) For certain cycles there
  may be evidence that the N-S asymmetry evolves with the solar cycle,
  but in general this is not the case. 8) There exists a slight but
  significant E-W asymmetry with a prolonged eastern excess.

---------------------------------------------------------
Title: Statistical Study of Solar Flares Observed in Soft X-Ray,
    Hard X-Ray and Hα Emission
Authors: Veronig, A.; Vršnak, B.; Temmer, M.; Magdalenić, J.;
   Hanslmeier, A.
2001HvaOB..25...39V    Altcode:
  Correlations among statistical properties of solar flares observed
  in soft X-rays, hard X-rays and Hα are studied. We investigate
  corresponding HXR flares measured by BATSE, SXR flares observed by GOES
  and Hα flares reported in the SGD for the period 1997--2000. Distinct
  correlations are found among the SXR peak flux and Hα area, as well
  as between the SXR peak flux and HXR fluence. This can be comprehended
  in the frame of the chromospheric evaporation model of flares.

---------------------------------------------------------
Title: Automatic Image Processing in the Frame of a Solar Flare
    Alerting System
Authors: Veronig, A.; Steinegger, M.; Otruba, W.; Hanslmeier, A.;
   Messerotti, M.; Temmer, M.; Gonzi, S.; Brunner, G.
2000HvaOB..24..195V    Altcode:
  In the present paper we describe image processing techniques applied
  to solar H-alpha full-disk images, with the objective of automatic
  and quasi real-time detection of the onset of H-alpha flares and
  describing their evolution. For this purpose we utilize a combination
  of region-based and edge-based image segmentation methods.

---------------------------------------------------------
Title: Automatic Image Segmentation and Feature Detection in Solar
    Full-Disk Images
Authors: Veronig, A.; Steinegger, M.; Otruba, W.; Hanslmeier, A.;
   Messerotti, M.; Temmer, M.; Brunner, G.; Gonzi, S.
2000ESASP.463..455V    Altcode: 2000sctc.proc..455V
  At Kanzelhoehe Solar Observatory, Austria, a solar activity monitoring
  and flare alerting system is under development, which will be based
  on the parametrization of solar flare activity using photometric and
  magnetic full-disk images of the Sun obtained simultaneously with high
  time cadence. An important step in this project is the automatic image
  segmentation and feature detection of solar activity phenomena related
  to the occurrence of solar flares. In a first step we have developed
  a procedure for automatically detecting the onset and describing the
  evolution of flares in H-alpha full-disk images.

---------------------------------------------------------
Title: Statistical Properties Relevant to Solar Flare Prediction
Authors: Temmer, M.; Veronig, A.; Hanslmeier, A.; Steinegger, M.;
   Brunner, G.; Gonzi, S.; Otruba, W.; Messerotti, M.
2000HvaOB..24..185T    Altcode:
  We statistically analyzed the characteristic temporal properties of
  H-alpha flares, such as duration, rising and setting times, with the aim
  to determine a proper acquisition rate for H-alpha patrol observations,
  which will be the basis for the automatic flare alerting and prediction
  system at the Kanzelhoehe Solar Observatory, Austria. Furthermore,
  the comparison of absolute and normalized values reveals interesting
  aspects on how flares of different importance classes behave with
  respect to the rising and decay phase.

---------------------------------------------------------
Title: Solar Activity Monitoring - a New Approach Using Combined
    Datasets, Pattern Recognition and Neural Networks
Authors: Hanslmeier, A.; Veronig, M.; Steinegger, M.; Brunner, G.;
   Gonzi, S.; Temmer, M.; Otruba, W.; Messerotti, M.
1999HvaOB..23...31H    Altcode:
  In this paper we give an overview of the activities of the recently
  established solar activity monitoring and flare alerting working group
  at the University of Graz and its planned activities. Solar flares
  can trigger events at the earth environment that can be dangerous to
  technological systems as well as to human life. Therefore, it is an
  important target in solar physics to predict such events, providing
  an essential contribution to space weather forecasts.