gallagher

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Author name code: gallagher
ADS astronomy entries on 2022-09-14
author:"Gallagher, Peter T."

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Title: Searching for stellar flares from low-mass stars using ASKAP
and TESS
Authors: Rigney, Jeremy; Ramsay, Gavin; Carley, Eoin P.; Doyle,
J. Gerry; Gallagher, Peter T.; Wang, Yuanming; Pritchard, Joshua;
Murphy, Tara; Lenc, Emil; Kaplan, David L.
2022MNRAS.516..540R Altcode: 2022MNRAS.tmp.2052R; 2022arXiv220700405R
Solar radio emission at low frequencies (&lt;1 GHz) can provide
valuable information on processes driving flares and coronal mass
ejections (CMEs). Radio emission has been detected from active M dwarf
stars, suggestive of much higher levels of activity than previously
thought. Observations of active M dwarfs at low frequencies can
provide information on the emission mechanism for high energy flares
and possible stellar CMEs. Here, we conducted two observations with
the Australian Square Kilometre Array Pathfinder Telescope totalling
26 h and scheduled to overlap with the Transiting Exoplanet Survey
Satellite Sector 36 field, utilizing the wide fields of view of both
telescopes to search for multiple M dwarfs. We detected variable
radio emission in Stokes I centred at 888 MHz from four known active
M dwarfs. Two of these sources were also detected with Stokes V
circular polarization. When examining the detected radio emission
characteristics, we were not able to distinguish between the models
for either electron cyclotron maser or gyrosynchrotron emission. These
detections add to the growing number of M dwarfs observed with variable
low-frequency emission.

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Title: Excitation of Langmuir waves at shocks and solar type II
radio bursts
Authors: Mann, G.; Vocks, C.; Warmuth, A.; Magdalenic, J.; Bisi, M.;
Carley, E.; Dabrowski, B.; Gallagher, P.; Krankowski, A.; Matyjasiak,
B.; Rotkaehl, H.; Zucca, P.
2022A&A...660A..71M Altcode:
Context. In the solar corona, shocks can be generated due to the
pressure pulse of a flare and/or driven by a rising coronal mass
ejection (CME). Coronal shock waves can be observed as solar type II
radio bursts in the Sun's radio radiation. In dynamic radio spectra,
they appear as stripes of an enhanced radio emission slowly drifting
from high to low frequencies. The radio emission is thought to be
plasma emission, that is to say the emission happens near the electron
plasma frequency and/or its harmonics. Plasma emission means that
energetic electrons excite Langmuir waves, which convert into radio
waves via non-linear plasma processes. Thus, energetic electrons are
necessary for plasma emission. In the case of type II radio bursts,
the energetic electrons are considered to be shock accelerated. 
Aims: Shock drift acceleration (SDA) is regarded as the mechanism for
producing energetic electrons in the foreshock region. SDA delivers
a shifted loss-cone velocity distribution function (VDF) for the
energetic electrons. The aim of the paper is to study in which way and
under which conditions a shifted loss-cone VDF of electrons excites
Langmuir waves in an efficient way in the corona. Methods:
By means of the results of SDA, the shape of the resulted VDF was
derived. It is a shifted loss-cone VDF showing both a loss-cone and a
beam-like component. The growth rates for exciting Langmuir waves were
calculated in the framework of Maxwell-Vlasov equations. The results
are discussed by employing plasma and shock parameters usually found
in the corona at the 25 MHz level. Results: We have found that
moderate coronal shocks with an Alfven-Mach number in the range 1.59
&lt; MA &lt; 2.53 are able to accelerate electrons up to
energies sufficient enough to excite Langmur waves, which convert into
radio waves seen as solar type II radio bursts.

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Title: Tracking a beam of electrons from the low solar corona into
interplanetary space with the Low Frequency Array, Parker Solar
Probe and 1 au spacecraft
Authors: Badman, Samuel T.; Carley, Eoin P.; Cañizares, Luis Alberto;
Dresing, Nina; Jian, Lan K.; Lario, David; Gallagher, Peter T.;
Martínez-Oliveros, Juan C.; Pulupa, Marc; Bale, Stuart D.
2022arXiv220408497B Altcode:
Type III radio bursts are the result of plasma emission from mildly
relativistic electron beams propagating from the low solar corona into
the heliosphere where they can eventually be detected in situ if they
align with the location of a heliospheric spacecraft. Here we observe
a type III radio burst from 0.1-16 MHz using the Parker Solar Probe
(PSP) FIELDS Radio Frequency Spectrometer (RFS), and from 10-80 MHz
using the Low Frequency Array (LOFAR). This event was not associated
with any detectable flare activity but was part of an ongoing noise
storm that occurred during PSP encounter 2. A deprojection of the
LOFAR radio sources into 3D space shows that the type III radio burst
sources were located on open magnetic field from 1.6-3 $R_\odot$ and
originated from a specific active region near the East limb. Combining
PSP/RFS observations with WIND/WAVES and Solar Terrestrial Relations
Observatory (STEREO)/WAVES, we reconstruct the type III radio source
trajectory in the heliosphere interior to PSP's position, assuming
ecliptic confinement. An energetic electron enhancement is subsequently
detected in situ at the STEREO-A spacecraft at compatible times although
the onset and duration suggests the individual burst contributes a
subset of the enhancement. This work shows relatively small-scale flux
emergence in the corona can cause the injection of electron beams from
the low corona into the heliosphere, without needing a strong solar
flare. The complementary nature of combined ground and space-based
radio observations, especially in the era of PSP, is also clearly
highlighted by this study.

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Title: Comparing the Heliospheric Cataloging, Analysis, and Techniques
Service (HELCATS) Manual and Automatic Catalogues of Coronal Mass
Ejections Using Solar Terrestrial Relations Observatory/Heliospheric
Imager (STEREO/HI) Data
Authors: Rodriguez, L.; Barnes, D.; Hosteaux, S.; Davies, J. A.;
Willems, S.; Pant, V.; Harrison, R. A.; Berghmans, D.; Bothmer, V.;
Eastwood, J. P.; Gallagher, P. T.; Kilpua, E. K. J.; Magdalenic, J.;
Mierla, M.; Möstl, C.; Rouillard, A. P.; Odstrčil, D.; Poedts, S.
2022SoPh..297...23R Altcode:
We present the results of a comparative study between automatic
and manually compiled coronal mass ejection (CME) catalogues based
on observations from the Heliospheric Imagers (HIs) onboard NASA's
Solar Terrestrial Relations Observatory (STEREO) spacecraft. Using
the Computer Aided CME Tracking software(CACTus), CMEs are identified
in HI data using an automatic feature-detection algorithm, while
the Heliospheric Imagers Catalogue(HICAT) includes CMEs that are
detected by visual inspection of HI images. Both catalogues were
compiled as part of the EU FP7 Heliospheric Cataloguing, Analysis and
Techniques Service (HELCATS) project (www.helcats-fp7.eu). We compare
observational parameters of the CMEs from CACTus to those listed in
HICAT, such as CME frequency, position angle (PA), and PA-width. We
also compare CACTus-derived speeds to speeds derived from applying
geometric modelling to the majority of the HICAT CMEs, the results
of which are listed in the HELCATS Heliospheric Imagers Geometric
Catalogue(HIGeoCAT). We find that both CACTus and HICAT catalogues
contain a similar number of events when we exclude events narrower than
20∘, which are not included in the HICAT catalogue but are
found to be identified by CACTus. PA-distributions are strongly peaked
around 90∘ and 270∘, with a slightly larger
CME frequency northwards of the equatorial plane (particularly for the
STEREO-A versions of both catalogues). The CME PA-widths in both HICAT
and CACTus catalogues peak at approximately 60∘. Manually
derived speeds from HIGeoCAT and automatically derived speeds by
CACTus correlate well for values lower than 1000 km s−1,
in particular when CMEs are propagating close to the plane of the sky.

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Title: LOFAR4SpaceWeather (LOFAR4SW) Increasing European Space-Weather
Capability with Europes Largest Radio Telescope: Completing the
Critical Design Review (CDR)
Authors: Bisi, Mario; Fallows, Richard; Vermeulen, Rene; Robertson,
Stuart; Ruiter, Mark; Vilmer, Nicole; Rothkaehl, Hanna; Matyjasiak,
Barbara; Verbiest, Joris; Carley, Eoin; Gallagher, Peter; Carozzi,
Tobia; Lindqvist, Michael; Olberg, Michael; Kruger, Paulus; Mevius,
Maaijke; Barnes, David; Chang, Oyuki; Baldovin, Carla
2021AGUFMSH45E2412B Altcode:
Space Weather research, monitoring, and operations are a very important
topics from the scientific, operational, and societal-impacts points of
view. Knowledge of interactions in the Sun-Earth system, the physics
behind observed space-weather phenomena, and its direct impact on
modern technologies are key areas of interest. This involves all
aspects of political, user, forecaster, and scientific engagement with
various stakeholders with the full recognition that space weather is a
worldwide threat with varied local, regional, continent-wide impacts,
and global impacts. The LOFAR For Space Weather (LOFAR4SW) project
(see: http://lofar4sw.eu/) is a Horizon 2020 (H2020) INFRADEV design
study to undertake investigations and perform a design study into
the upgrading of the Low Frequency Array (LOFAR). The project aims to
prepare a novel design pathway which can bring new capabilities into
the space-weather domain. LOFAR is presently the world's largest low
frequency radio telescope consisting of a dense core of 24 stations near
Exloo in The Netherlands, an additional 14 stations spread across the
northeast Netherlands, and a further 14 stations based internationally
across Europe. These international stations are six across Germany,
three in northern Poland, and one each in France, Ireland, Latvia,
Sweden, and the UK. Further sites are being planned across Europe. The
final design of LOFAR4SW will provide a comprehensive conceptual
and technical description of the necessary LOFAR upgrades needed to
enable simultaneous operation as a radio telescope for astronomical
research as well as an infrastructure working for space-weather studies
and monitoring. In this work we present the overview of the LOFAR4SW
project, examples of its capabilities and will summarise the outcomes
of the Critical Design Review (CDR) planned to be held virtually 21-23
September 2021. A fully-envisage longer-term goal of enable a LOFAR4SW
update would make LOFAR one of Europes most-comprehensive space-weather
observing systems capable of shedding new light on several aspects of
the space-weather system, from the Sun to the solar wind to Jupiter
and Earths ionosphere.

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Title: STIX X-ray microflare observations during the Solar Orbiter
commissioning phase
Authors: Battaglia, Andrea Francesco; Saqri, Jonas; Massa, Paolo;
Perracchione, Emma; Dickson, Ewan C. M.; Xiao, Hualin; Veronig,
Astrid M.; Warmuth, Alexander; Battaglia, Marina; Hurford, Gordon J.;
Meuris, Aline; Limousin, Olivier; Etesi, László; Maloney, Shane A.;
Schwartz, Richard A.; Kuhar, Matej; Schuller, Frederic; Senthamizh
Pavai, Valliappan; Musset, Sophie; Ryan, Daniel F.; Kleint, Lucia;
Piana, Michele; Massone, Anna Maria; Benvenuto, Federico; Sylwester,
Janusz; Litwicka, Michalina; Stȩślicki, Marek; Mrozek, Tomasz;
Vilmer, Nicole; Fárník, František; Kašparová, Jana; Mann,
Gottfried; Gallagher, Peter T.; Dennis, Brian R.; Csillaghy, André;
Benz, Arnold O.; Krucker, Säm
2021A&A...656A...4B Altcode: 2021arXiv210610058B
Context. The Spectrometer/Telescope for Imaging X-rays (STIX) is the
hard X-ray instrument onboard Solar Orbiter designed to observe solar
flares over a broad range of flare sizes. Aims: We report
the first STIX observations of solar microflares recorded during
the instrument commissioning phase in order to investigate the STIX
performance at its detection limit. Methods: STIX uses hard
X-ray imaging spectroscopy in the range between 4-150 keV to diagnose
the hottest flare plasma and related nonthermal electrons. This first
result paper focuses on the temporal and spectral evolution of STIX
microflares occuring in the Active Region (AR) AR12765 in June 2020,
and compares the STIX measurements with Earth-orbiting observatories
such as the X-ray Sensor of the Geostationary Operational Environmental
Satellite (GOES/XRS), the Atmospheric Imaging Assembly of the Solar
Dynamics Observatory, and the X-ray Telescope of the Hinode mission. Results: For the observed microflares of the GOES A and B class, the
STIX peak time at lowest energies is located in the impulsive phase of
the flares, well before the GOES peak time. Such a behavior can either
be explained by the higher sensitivity of STIX to higher temperatures
compared to GOES, or due to the existence of a nonthermal component
reaching down to low energies. The interpretation is inconclusive
due to limited counting statistics for all but the largest flare
in our sample. For this largest flare, the low-energy peak time is
clearly due to thermal emission, and the nonthermal component seen at
higher energies occurs even earlier. This suggests that the classic
thermal explanation might also be favored for the majority of the
smaller flares. In combination with EUV and soft X-ray observations,
STIX corroborates earlier findings that an isothermal assumption
is of limited validity. Future diagnostic efforts should focus on
multi-wavelength studies to derive differential emission measure
distributions over a wide range of temperatures to accurately describe
the energetics of solar flares. Conclusions: Commissioning
observations confirm that STIX is working as designed. As a rule of
thumb, STIX detects flares as small as the GOES A class. For flares
above the GOES B class, detailed spectral and imaging analyses can
be performed.

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Title: First results from the REAL-time Transient Acquisition backend
(REALTA) at the Irish LOFAR station
Authors: Murphy, P. C.; Callanan, P.; McCauley, J.; McKenna, D. J.;
Fionnagáin, D. Ó.; Louis, C. K.; Redman, M. P.; Cañizares,
L. A.; Carley, E. P.; Maloney, S. A.; Coghlan, B.; Daly, M.; Scully,
J.; Dooley, J.; Gajjar, V.; Giese, C.; Brennan, A.; Keane, E. F.;
Maguire, C. A.; Quinn, J.; Mooney, S.; Ryan, A. M.; Walsh, J.; Jackman,
C. M.; Golden, A.; Ray, T. P.; Doyle, J. G.; Rigney, J.; Burton, M.;
Gallagher, P. T.
2021A&A...655A..16M Altcode: 2021arXiv210811251M
Modern radio interferometers such as the LOw Frequency ARray (LOFAR)
are capable of producing data at hundreds of gigabits to terabits per
second. This high data rate makes the analysis of radio data cumbersome
and computationally expensive. While high performance computing
facilities exist for large national and international facilities, that
may not be the case for instruments operated by a single institution or
a small consortium. Data rates for next generation radio telescopes are
set to eclipse those currently in operation, hence local processing
of data will become all the more important. Here, we introduce the
REAL-time Transient Acquisition backend (REALTA), a computing backend
at the Irish LOFAR station (I-LOFAR) which facilitates the recording
of data in near real-time and post-processing. We also present first
searches and scientific results of a number of radio phenomena observed
by I-LOFAR and REALTA, including pulsars, fast radio bursts, rotating
radio transients, the search for extraterrestrial intelligence, Jupiter,
and the Sun.

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Title: Observing Jupiter's radio emissions using multiple LOFAR
stations: a first case study of the Io-decametric emission using
the Irish IE613, French FR606 and German DE604 stations
Authors: Louis, Corentin K.; Jackman, Caitriona M.; Griessmeier,
Jean-Mathias; Wucknitz, Olaf; McKenna, David J.; Murphy, Pearse;
Gallagher, Peter T.; Carley, Eoin; Fionnagáin, Dúalta Ó; Golden,
Aaron; McCauley, Joe; Callanan, Paul; Redman, Matt; Vocks, Christian
2021arXiv211109599L Altcode:
The Low Frequency Array (LOFAR) is an international radio telescope
array, consisting of 38 stations in the Netherlands and 14 international
stations spread over Europe. Here we present an observation method
to study the jovian decametric radio emissions from several LOFAR
stations (here DE604, FR606 and IE613), at high temporal and spectral
resolution. This method is based on prediction tools, such as radio
emission simulations and probability maps, and data processing. We
report an observation of Io-induced decametric emission from June 2021,
and a first case study of the substructures that compose the macroscopic
emissions (called millisecond bursts). The study of these bursts make it
possible to determine the electron populations at the origin of these
emissions. We then present several possible future avenues for study
based on these observations. The methodology and study perspectives
described in this paper can be applied to new observations of jovian
radio emissions induced by Io, but also by Ganymede or Europa, or
jovian auroral radio emissions.

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Title: Solar Flare Effects on the Earth's Lower Ionosphere
Authors: Hayes, Laura A.; O'Hara, Oscar S. D.; Murray, Sophie A.;
Gallagher, Peter T.
2021SoPh..296..157H Altcode: 2021arXiv210906558H
Solar flares significantly impact the conditions of the Earth's
ionosphere. In particular, the sudden increase in X-ray flux during
a flare penetrates down to the lowest-lying D-region and dominates
ionization at these altitudes (≈60 - 100 km). Measurements of very
low frequency (VLF: 3 - 30 kHz) radio waves that reflect at D-region
altitudes provide a unique remote-sensing probe to investigate the
D-region response to solar-flare emissions. Here, using a combination of
VLF amplitude measurements at 24 kHz together with X-ray observations
from the Geostationary Operational Environment Satellite (GOES)
X-ray sensor, we present a large-scale statistical study of 334
solar-flare events and their impacts on the D-region over the past solar
cycle. Focusing on both GOES broadband X-ray channels, we investigate
how the flare peak fluxes and position on the solar disk dictate an
ionospheric response and extend this to investigate the characteristic
time delay between incident X-ray flux and the D-region response. We
show that the VLF amplitude linearly correlates with both the 1 - 8
Å and 0.5 - 4 Å channels, with correlation coefficients of 0.80 and
0.79, respectively. For the two X-class flares in our sample, however,
there appears to be a turnover in the linear relationship, similar to
previous works. Unlike higher altitude ionospheric regions for which
the location of the flare on the solar disk affects the ionospheric
response, we find that the D-region response to solar flares does not
depend on the flare location. By comparing the time delays between the
peak X-ray fluxes in both GOES channels and VLF amplitudes, we find that
there is an important difference between the D-region response and the
X-ray spectral band. We also demonstrate for several flare events that
show a negative time delay, the peak VLF amplitude matches with the
impulsive 25 - 50 keV hard X-ray fluxes measured by the Ramaty High
Energy Solar Spectroscopic Imager (RHESSI). These results highlight
the importance of performing full spectral analysis when studying the
ionospheric responses to solar flares.

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Title: Quasi-Periodic Particle Acceleration in a Solar Flare
Authors: Clarke, B. P.; Hayes, L. A.; Gallagher, P. T.; Maloney,
S. A.; Carley, E. P.
2021AAS...23830303C Altcode:
A common feature of electromagnetic emission from solar flares is the
presence of intensity pulsations that vary as a function of time. Known
as quasi-periodic pulsations (QPPs), these variations in flux appear
to include periodic components and characteristic time-scales. Here,
we analyse a GOES M3.7 class flare exhibiting pronounced QPPs across
a broad band of wavelengths using imaging and timeseries analysis. We
identify QPPs in the timeseries of X-ray, low frequency radio and EUV
wavelengths using wavelet analysis, and localise the region of the
flare site from which the QPPs originate via X-ray and EUV imaging. It
was found that the pulsations within the 171 A, 1600 A, soft X-ray
(SXR), and hard X-ray (HXR) light curves yielded similar periods of
~122 s, ~131 s, ~123 s, and ~137 s, respectively, indicating a common
progenitor. The low frequency radio emission at 2.5 MHz contained a
longer period of ∼231 s. Imaging analysis indicates that the location
of the X-ray and EUV pulsations originates from a HXR footpoint
linked to a system of nearby open magnetic field lines. Our results
suggest that intermittent particle acceleration, likely due to 'bursty'
magnetic reconnection, is responsible for the QPPs. The precipitating
electrons accelerated towards the chromosphere produce the X-ray and
EUV pulsations, while the escaping electrons result in low frequency
radio pulses in the form of type III radio bursts. The modulation of
the reconnection process, resulting in episodic particle acceleration,
explains the presence of these QPPs across the entire spatial range
of flaring emission.

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Title: The flare likelihood and region eruption forecasting
(FLARECAST) project: flare forecasting in the big data &amp; machine
learning era
Authors: Georgoulis, Manolis K.; Bloomfield, D. Shaun; Piana,
Michele; Massone, Anna Maria; Soldati, Marco; Gallagher, Peter T.;
Pariat, Etienne; Vilmer, Nicole; Buchlin, Eric; Baudin, Frederic;
Csillaghy, Andre; Sathiapal, Hanna; Jackson, David R.; Alingery,
Pablo; Benvenuto, Federico; Campi, Cristina; Florios, Konstantinos;
Gontikakis, Constantinos; Guennou, Chloe; Guerra, Jordan A.;
Kontogiannis, Ioannis; Latorre, Vittorio; Murray, Sophie A.; Park,
Sung-Hong; von Stachelski, Samuelvon; Torbica, Aleksandar; Vischi,
Dario; Worsfold, Mark
2021JSWSC..11...39G Altcode: 2021arXiv210505993G
The European Union funded the FLARECAST project, that ran from January
2015 until February 2018. FLARECAST had a research-to-operations
(R2O) focus, and accordingly introduced several innovations into the
discipline of solar flare forecasting. FLARECAST innovations were:
first, the treatment of hundreds of physical properties viewed as
promising flare predictors on equal footing, extending multiple
previous works; second, the use of fourteen (14) different machine
learning techniques, also on equal footing, to optimize the immense
Big Data parameter space created by these many predictors; third,
the establishment of a robust, three-pronged communication effort
oriented toward policy makers, space-weather stakeholders and the wider
public. FLARECAST pledged to make all its data, codes and infrastructure
openly available worldwide. The combined use of 170+ properties (a
total of 209 predictors are now available) in multiple machine-learning
algorithms, some of which were designed exclusively for the project,
gave rise to changing sets of best-performing predictors for the
forecasting of different flaring levels, at least for major flares. At
the same time, FLARECAST reaffirmed the importance of rigorous training
and testing practices to avoid overly optimistic pre-operational
prediction performance. In addition, the project has (a) tested new
and revisited physically intuitive flare predictors and (b) provided
meaningful clues toward the transition from flares to eruptive flares,
namely, events associated with coronal mass ejections (CMEs). These
leads, along with the FLARECAST data, algorithms and infrastructure,
could help facilitate integrated space-weather forecasting efforts
that take steps to avoid effort duplication. In spite of being
one of the most intensive and systematic flare forecasting efforts
to-date, FLARECAST has not managed to convincingly lift the barrier of
stochasticity in solar flare occurrence and forecasting: solar flare
prediction thus remains inherently probabilistic.

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Title: Type III solar radio burst detection and classification:
A deep learning approach
Authors: Scully, Jeremiah; Flynn, Ronan; Carley, Eoin; Gallagher,
Peter; Daly, Mark
2021arXiv210513387S Altcode:
Solar Radio Bursts (SRBs) are generally observed in dynamic spectra and
have five major spectral classes, labelled Type I to Type V depending
on their shape and extent in frequency and time. Due to their complex
characterisation, a challenge in solar radio physics is the automatic
detection and classification of such radio bursts. Classification of
SRBs has become fundamental in recent years due to large data rates
generated by advanced radio telescopes such as the LOw-Frequency ARray,
(LOFAR). Current state-of-the-art algorithms implement the Hough or
Radon transform as a means of detecting predefined parametric shapes
in images. These algorithms achieve up to 84% accuracy, depending on
the Type of radio burst being classified. Other techniques include
procedures that rely on Constant-FalseAlarm-Rate detection, which is
essentially detection of radio bursts using a de-noising and adaptive
threshold in dynamic spectra. It works well for a variety of different
Types of radio bursts and achieves an accuracy of up to 70%. In this
research, we are introducing a methodology named You Only Look Once
v2 (YOLOv2) for solar radio burst classification. By using Type III
simulation methods we can train the algorithm to classify real Type
III solar radio bursts in real-time at an accu

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Title: Failure to forecast: A case study in nowcasting and forecasting
the eruption of a coronal mass ejection and its geomagnetic impacts
on Dec 7-10, 2020.
Authors: Gallagher, Peter; Murray, Sophie; Malone-Leigh, John;
Campanyà, Joan; Cañizares, Alberto; Carley, Eoin; Blake, Seán
2021EGUGA..2315520G Altcode:
Forecasting solar flares based on while-light images and
photospheric magnetograms of sunspots is notoriously challenging,
while accurate forecasting of coronal mass ejections (CME) is still in
its infancy. That said, the chances of a CME being launched is more
likely following a flare. CMEs launched from the western hemisphere
and "halo" CMEs are the most likely to be geomagnetically impactful,
but forecasting their arrival and impact at Earth depends on how
well their velocity is known near the Sun, the solar wind conditions
between the Sun and the Earth, the accuracy of theoretical models and
on the orientation of the CME magnetic field. In this presentation,
we describe a well observed active region, flare, CME, radio burst
and sudden geomagnetic impulse that was observed on December 7-10,
2020 by a slew of instruments (SDO, ACE, DSCOVR, PSP, US and European
magnetometers). This was a solar eruption that was not expected, but the
CME and resulting geomagnetic impact should have been straight-forward
to model and forecast. What can we learn from our failure to forecast
this simple event and its impacts at Earth?

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Title: LOFAR observations of a jet-driven piston shock in the low
solar corona
Authors: Maguire, Ciara; Carley, Eoin; Zucca, Pietro; Vilmer, Nicole;
Gallagher, Peter
2021EGUGA..23.7602M Altcode:
The Sun produces highly dynamic and eruptive events that can drive
shocks through the corona. These shocks can accelerate electrons, which
result in plasma emission in the form of a type II radio burst. Despite
a large number of type II radio bursts observations, the precise origin
of coronal shocks is still subject to investigation. Here we present a
well-observed solar eruptive event that occurred on 16 October 2015,
focusing on a jet observed in the extreme ultraviolet by the SDO
Atmospheric Imaging Assembly, a streamer observed in white-light by the
Large Angle and Spectrometric Coronagraph, and a metric type II radio
burst observed by the LOw-Frequency Array (LOFAR) radio telescope. For
the first time, LOFAR has interferometrically imaged the fundamental
and harmonic sources of a type II radio burst and revealed that the
sources did not appear to be co-spatial, as would be expected from
the plasma emission mechanism. We correct for the separation between
the fundamental and harmonic using a model which accounts for the
scattering of radio waves by electron density fluctuations in a
turbulent plasma. This allows us to show the type II radio sources
were located ∼0.5 Rsun above the jet and propagated at a speed of
∼1000 km s-1, which was significantly faster than the jet speed of
∼200 km s-1. This suggests that the type II burst was generated by
a piston shock driven by the jet in the low corona.

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Title: LOFAR4SW - Space Weather Science and Operations with LOFAR
Authors: Rothkaehl, Hanna; Matyjasiak, Barbara; Baldovin, Carla;
Bisi, Mario; Barnes, David; Carley, Eoin; Carozzi, Tobia; Fallows,
Richard A.; Gallagher, Peter T.; Mevius, Maaijke; Robertson, Stuart
C.; Ruiter, Mark; Verbiest, Joris; Vermeulen, Renne; Vilmer, Nicole
2021EGUGA..23.6455R Altcode:
Space Weather (SW) research is a very important topic from the
scientific, operational and civic society point of view. Knowledge
of interactions in the Sun-Earth system, the physics behind observed
SW phenomena, and its direct impact on modern technologies were and
will be key areas of interest. The LOFAR for Space Weather (LOFAR4SW)
project aim is to prepare a novel tool which can bring new capabilities
into this domain. The project is realised in the frame of a Horizon
2020 INFRADEV call. The base for the project is the Low Frequency
Array (LOFAR) - the worlds largest low frequency radio telescope,
with a dense core near Exloo in The Netherlands and many stations
distributed both in the Netherlands and Europe wide with baselines up
to 2000 km. The final design of LOFAR4SW will provide a full conceptual
and technical description of the LOFAR upgrade, to enable simultaneous
operation as a radio telescope for astronomical research as well as
an infrastructure working for Space Weather studies. In this work we
present the current status of the project, including examples of the
capabilities of LOFAR4SW and the project timeline as we plan for the
Critical Design Review later in 2021.

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Title: LOFAR Imaging of the Solar Corona during the 2015 March 20
Solar Eclipse
Authors: Ryan, Aoife Maria; Gallagher, Peter T.; Carley, Eoin P.;
Brentjens, Michiel A.; Murphy, Pearse C.; Vocks, Christian; Morosan,
Diana E.; Reid, Hamish; Magdalenic, Jasmina; Breitling, Frank;
Zucca, Pietro; Fallows, Richard; Mann, Gottfried; Kerdraon, Alain;
Halfwerk, Ronald
2021EGUGA..2311094R Altcode:
The solar corona is a highly-structured plasma which can reach
temperatures of more than 2 MK. At low frequencies (decimetric and
metric wavelengths), scattering and refraction of electromagnetic waves
are thought to considerably increase the imaged radio source sizes
(up to a few arcminutes). However, exactly how source size relates to
scattering due to turbulence is still subject to investigation. The
theoretical predictions relating source broadening to propagation
effects have not been fully confirmed by observations, due to the
rarity of high spatial resolution observations of the solar corona
at low frequencies. Here, the LOw Frequency ARray (LOFAR) was used to
observe the solar corona at 120-180 MHz using baselines of up to 3.5
km (corresponding to a resolution of 1-2") during the partial solar
eclipse of 2015 March 20. A lunar de-occultation technique was used
to achieve higher spatial resolution (0.6") than that attainable
via standard interferometric imaging (2.4"). This provides a means
of studying the contribution of scattering to apparent source size
broadening. This study shows that the de-occultation technique can
reveal a more structured quiet corona that is not resolved from standard
imaging, implying scattering may be overestimated in this region when
using standard imaging techniques. However, an active region source was
measured to be 4" using both de-occultation and standard imaging. This
may be explained by increased scattering of radio waves by turbulent
density fluctuations in active regions, which is more severe than in
the quiet Sun.

---------------------------------------------------------
Title: LOFAR imaging of the solar corona during the 2015 March 20
solar eclipse
Authors: Ryan, A. M.; Gallagher, P. T.; Carley, E. P.; Brentjens,
M. A.; Murphy, P. C.; Vocks, C.; Morosan, D. E.; Reid, H.; Magdalenic,
J.; Breitling, F.; Zucca, P.; Fallows, R.; Mann, G.; Kerdraon, A.;
Halfwerk, R.
2021A&A...648A..43R Altcode: 2021arXiv210205552R
The solar corona is a highly-structured plasma which can reach
temperatures of more than ∼2 MK. At low frequencies (decimetric and
metric wavelengths), scattering and refraction of electromagnetic waves
are thought to considerably increase the imaged radio source sizes
(up to a few arcminutes). However, exactly how source size relates to
scattering due to turbulence is still subject to investigation. The
theoretical predictions relating source broadening to propagation
effects have not been fully confirmed by observations due to the rarity
of high spatial resolution observations of the solar corona at low
frequencies. Here, the LOw Frequency ARray (LOFAR) was used to observe
the solar corona at 120−180 MHz using baselines of up to ∼3.5 km
(corresponding to a resolution of ∼1−2') during the partial solar
eclipse of 2015 March 20. A lunar de-occultation technique was used
to achieve higher spatial resolution (∼0.6') than that attainable
via standard interferometric imaging (∼2.4'). This provides a means
of studying the contribution of scattering to apparent source size
broadening. It was found that the de-occultation technique reveals
a more structured quiet corona that is not resolved from standard
imaging, implying scattering may be overestimated in this region when
using standard imaging techniques. However, an active region source
was measured to be ∼4' using both de-occultation and standard
imaging. This may be explained by the increased scattering of radio
waves by turbulent density fluctuations in active regions, which is
more severe than in the quiet Sun.

---------------------------------------------------------
Title: Quasi-periodic Particle Acceleration in a Solar Flare
Authors: Clarke, Brendan P.; Hayes, Laura A.; Gallagher, Peter T.;
Maloney, Shane A.; Carley, Eoin P.
2021ApJ...910..123C Altcode: 2021arXiv210204267C
A common feature of electromagnetic emission from solar flares is
the presence of intensity pulsations that vary as a function of
time. Known as quasi-periodic pulsations (QPPs), these variations
in flux appear to include periodic components and characteristic
timescales. Here, we analyze a GOES M3.7 class flare exhibiting
pronounced QPPs across a broad band of wavelengths using imaging and
time series analysis. We identify QPPs in the time series of X-ray,
low-frequency radio, and extreme ultraviolet (EUV) wavelengths using
wavelet analysis, and localize the region of the flare site from which
the QPPs originate via X-ray and EUV imaging. It was found that the
pulsations within the 171 Å, 1600 Å, soft X-ray, and hard X-ray light
curves yielded similar periods of ${122}_{-22}^{+26}$ &lt;!-- --&gt;
s, ${131}_{-27}^{+36}$ &lt;!-- --&gt; s, ${123}_{-26}^{+11}$ &lt;!--
--&gt; s, and ${137}_{-56}^{+49}$ &lt;!-- --&gt; s, respectively,
indicating a common progenitor. The low-frequency radio emission at 2.5
MHz contained a longer period of ∼231 s. Imaging analysis indicates
that the location of the X-ray and EUV pulsations originates from a
hard X-ray footpoint linked to a system of nearby open magnetic field
lines. Our results suggest that intermittent particle acceleration,
likely due to "bursty" magnetic reconnection, is responsible for the
QPPs. The precipitating electrons accelerated toward the chromosphere
produce the X-ray and EUV pulsations, while the escaping electrons
result in low-frequency radio pulses in the form of type III radio
bursts. The modulation of the reconnection process, resulting in
episodic particle acceleration, explains the presence of these QPPs
across the entire spatial range of flaring emission.

---------------------------------------------------------
Title: LOFAR Observations of a Jet-driven Piston Shock in the Low
Solar Corona
Authors: Maguire, Ciara A.; Carley, Eoin P.; Zucca, Pietro; Vilmer,
Nicole; Gallagher, Peter T.
2021ApJ...909....2M Altcode: 2021arXiv210105569M
The Sun produces highly dynamic and eruptive events that can drive
shocks through the corona. These shocks can accelerate electrons, which
result in plasma emission in the form of a type II radio burst. Despite
the large number of type II radio burst observations, the precise
origin of coronal shocks is still subject to investigation. Here,
we present a well-observed solar eruptive event that occurred on 2015
October 16, focusing on a jet observed in the extreme ultraviolet by the
Atmospheric Imaging Assembly (SDO/AIA), a streamer observed in white
light by the Large Angle and Spectrometric Coronagraph (SOHO/LASCO),
and a metric type II radio burst observed by the LOw Frequency Array
(LOFAR). LOFAR interferometrically imaged the fundamental and harmonic
sources of a type II radio burst and revealed that the sources did not
appear to be cospatial, as would be expected from the plasma emission
mechanism. We correct for the separation between the fundamental and
harmonic using a model that accounts for scattering of radio waves by
electron density fluctuations in a turbulent plasma. This allows us
to show the type II radio sources were located ∼0.5R⊙
above the jet and propagated at a speed of ∼1000 km s-1,
which was significantly faster than the jet speed of ∼200 km
s-1. This suggests that the type II burst was generated by
a piston shock driven by the jet in the low corona.

---------------------------------------------------------
Title: Nonthermal electrons revealed by LOFAR
Authors: Zucca, Pietro; Pellizzoni, Alberto; Krankowski, Andrzej;
Rothkaehl, Hanna; Mann, Gottfried; Vocks, Christian; Magdalenic,
Jasmina; Marque, Christophe; Jackson, Bernard; Fallows, Richard;
Tomasik, Lukasz; Hamish; Reid, A. S.; Gallagher, Peter; Vourlidas,
Angelos; Bisi, Mario M.; Carley, Eoin; Matyjasiak, Barbara; Kozarev,
Kamen; Dabrowski, Bartosz; Morosan, Diana; Tiburzi, Caterina; Chang,
Peijin
2021cosp...43E1065Z Altcode:
During solar flares and CMEs, the corona is heated, plasma motion,
waves and shocks are ignited, and particles are accelerated. The
accelerated particles propagate through the solar corona causing a
variety of plasma instabilities that lead to enhanced non-thermal
radio emission, known as "radio bursts". By studying radio-bursts'
characteristics we can gain insight into the properties of energetic
particles and the ambient coronal plasma, and the properties of particle
acceleration mechanisms, such as magnetic reconnection and/or shocks
in the solar atmosphere. The Low Frequency aRray (LOFAR) can be used
to study the fundamental plasma physics of solar radio bursts with
unprecedented time resolution in dynamic spectra, as well as with
both interferometric imaging and tied array imaging. In this talk, an
overview of recent results obtained with the LOFAR telescope will be
given, including observations of a different variety of radio bursts
such as type II, III and IV. These observations were performed with
simultaneous beam formed and interferometric imaging, resulting in
unprecedented special resolution with baselines up to ~120 km. Finally,
we will present the plan for future observations and the remaining
challenges of solar-heliospheric low-frequency observations.

---------------------------------------------------------
Title: Results from the LOFAR coordination with PSP
Authors: Zucca, Pietro; Pellizzoni, Alberto; Krankowski, Andrzej;
Rothkaehl, Hanna; Mann, Gottfried; Vocks, Christian; Magdalenic,
Jasmina; Marque, Christophe; Jackson, Bernard; Fallows, Richard;
Tomasik, Lukasz; Miteva, Rositsa; Hamish; Reid, A. S.; Gallagher,
Peter; Vourlidas, Angelos; Bisi, Mario M.; Carley, Eoin; Matyjasiak,
Barbara; Kozarev, Kamen; Dabrowski, Bartosz; Morosan, Diana; Tiburzi,
Caterina; Zhabngm, Peijin
2021cosp...43E.945Z Altcode:
Understanding and modelling the complex state of the Sun-solar
wind-magnetosphere-ionosphere-thermosphere system, requires a
comprehensive set of multiwavelength observations. LOFAR has unique
capabilities in the radio domain. Some examples of these include: a)
the ability to take high-resolution solar dynamic spectra and radio
images of the Sun; b) observing the scintillation (interplanetary
scintillation - IPS) of distant, compact, astronomical radio sources
to determine the density, velocity and turbulence structure of the
solar wind; and c) the use of Faraday rotation as a tool to probe
the interplanetary magnetic-field strength and direction. However, to
better understand and predict how the Sun, its atmosphere, and more
in general the Heliosphere works and impacts Earth, the combination
of in-situ spacecraft measurements and ground-based remote-sensing
observations of coronal and heliospheric plasma parameters is extremely
useful. Ground-based observations can be used to infer a global
picture of the inner heliosphere, providing the essential context into
which in-situ measurements from spacecraft can be placed. Conversely,
remote-sensing observations usually contain information from extended
lines of sight, with some deconvolution and modelling necessary to build
up a three-dimensional (3-D) picture. Precise spacecraft measurements,
when calibrated, can provide ground truth to constrain these models. The
PSP mission is observing the solar corona and near-Sun interplanetary
space. It has a highly-elliptical orbit taking the spacecraft as close
as nearly 36 solar radii from the Sun centre on its first perihelion
passage, and subsequent passages ultimately reaching as close as 9.8
solar radii. Four instruments are on the spacecraft's payload: FIELDS
measuring the radio emission, electric and magnetic fields, Poynting
flux, and plasma waves as well as the electron density and temperature;
ISOIS measuring energetic electrons, protons, and heavy ions in the
energy range 10 keV-100 MeV; SWEAP measuring the density, temperature,
and flow speed of electrons, protons, and alphas in the solar wind;
and finally, WISPR imaging coronal streamers, coronal mass ejections
(CMEs), their associated shocks, and other solar wind structures in the
corona and near-Sun interplanetary space, and provide context for the
other three in-situ instruments. In this talk, several results of the
joint LOFAR/PSP campaign will be presented, including fine structures
of radio bursts, localization and kinematics of propagating radio
sources in the heliosphere, and the challenges and plans for future
observing campaigns including PSP and Solar Orbiter.

---------------------------------------------------------
Title: LOFAR observations of radio burst source sizes and scattering
in the solar corona
Authors: Murphy, Pearse C.; Carley, Eoin P.; Ryan, Aoife Maria; Zucca,
Pietro; Gallagher, Peter T.
2021A&A...645A..11M Altcode: 2020arXiv201113735M
Low frequency radio wave scattering and refraction can have a dramatic
effect on the observed size and position of radio sources in the
solar corona. The scattering and refraction is thought to be due
to fluctuations in electron density caused by turbulence. Hence,
determining the true radio source size can provide information on
the turbulence in coronal plasma. However, the lack of high spatial
resolution radio interferometric observations at low frequencies,
such as with the LOw Frequency ARray (LOFAR), has made it difficult
to determine the true radio source size and level of radio wave
scattering. Here we directly fit the visibilities of a LOFAR observation
of a Type IIIb radio burst with an elliptical Gaussian to determine its
source size and position. This circumvents the need to image the source
and then de-convolve LOFAR's point spread function, which can introduce
spurious effects to the source size and shape. For a burst at 34.76
MHz, we find full width at half maximum (FWHM) heights along the major
and minor axes to be 18.8' ± 0.1' and 10.2' ± 0.1', respectively,
at a plane of sky heliocentric distance of 1.75 R⊙. Our
results suggest that the level of density fluctuations in the solar
corona is the main cause of the scattering of radio waves, resulting
in large source sizes. However, the magnitude of ɛ may be smaller
than what has been previously derived in observations of radio wave
scattering in tied-array images.

---------------------------------------------------------
Title: LOFAR4SpaceWeather (LOFAR4SW) - Increasing European
Space-Weather Capability with Europe's Largest Radio Telescope:
Preparing for the Critical Design Review (CDR)
Authors: Bisi, M. M.; Fallows, R. A.; Vermeulen, R.; Robertson, S. C.;
Ruiter, M.; Vilmer, N.; Rothkaehl, H.; Matyjasiak, B.; Verbiest, J.;
Carley, E.; Gallagher, P.; Carozzi, T.; Lindqvist, M.; Olberg, M.;
Kruger, P.; Mevius, M.; Barnes, D.; Chang, O.; Baldovin, C.
2020AGUFMSH0030021B Altcode:
The Low Frequency Array (LOFAR) consists of a dense core of 24 stations
near Exloo in The Netherlands, an additional 14 stations spread
across the northeast Netherlands, and a further 14 stations based
internationally across Europe. These international stations are six
in Germany, three in northern Poland, and one each in France, Ireland,
Latvia, Sweden, and the UK. LOFAR can observe over a wide bandwidth of
radio frequencies (~10-250 MHz) at high spatial/temporal resolutions. It
has capabilities that enable studies of several aspects of space
weather to be progressed well beyond today's state-of-the-art. However,
with its present governance it can only be used for space-weather
campaign studies. This severely limits LOFAR's ability to contribute to
space-weather monitoring/forecast beyond its core strength of enabling
world-leading scientific research. The LOFAR For Space Weather
(LOFAR4SW) project (see: http://lofar4sw.eu/) is a Horizon 2020 (H2020)
INFRADEV design study to undertake investigations into upgrading LOFAR
to allow for regular space-weather science/monitoring observations
in parallel with normal radio-astronomy/scientific operations. This
involves all aspects of political, user, forecaster, and scientific
engagement with various stakeholders with the full recognition that
space weather is a worldwide threat with varied local, regional,
continent-wide impacts, and global impacts. Here, we summarise
the most-recent key aspects of the LOFAR4SW progress including
outputs/progress following the Detailed Design Review (DDR) and
User Workshop, and particularly our plans for the Critical Design
Review (CDR) which is now delayed due to COVID-19 effects on project
progress. A fully-envisage longer-term goal of enable a LOFAR4SW
update would make LOFAR one of Europe's most-comprehensive space-weather
observing systems capable of shedding new light on several aspects of
the space-weather system, from the Sun to the solar wind to Jupiter
and Earth's ionosphere.

---------------------------------------------------------
Title: CMEs in the Heliosphere: III. A Statistical Analysis of the
Kinematic Properties Derived from Stereoscopic Geometrical Modelling
Techniques Applied to CMEs Detected in the Heliosphere from 2008 to
2014 by STEREO/HI-1
Authors: Barnes, D.; Davies, J. A.; Harrison, R. A.; Byrne, J. P.;
Perry, C. H.; Bothmer, V.; Eastwood, J. P.; Gallagher, P. T.; Kilpua,
E. K. J.; Möstl, C.; Rodriguez, L.; Rouillard, A. P.; Odstrčil, D.
2020SoPh..295..150B Altcode: 2020arXiv200614879B
We present an analysis of coronal mass ejections (CMEs) observed
by the Heliospheric Imagers (HIs) onboard NASA's Solar Terrestrial
Relations Observatory (STEREO) spacecraft. Between August 2008 and
April 2014 we identify 273 CMEs that are observed simultaneously,
by the HIs on both spacecraft. For each CME, we track the observed
leading edge, as a function of time, from both vantage points,
and apply the Stereoscopic Self-Similar Expansion (SSSE) technique
to infer their propagation throughout the inner heliosphere. The
technique is unable to accurately locate CMEs when their observed
leading edge passes between the spacecraft; however, we are able to
successfully apply the technique to 151, most of which occur once the
spacecraft-separation angle exceeds 180∘, during solar
maximum. We find that using a small half-width to fit the CME can
result in inferred acceleration to unphysically high velocities and that
using a larger half-width can fail to accurately locate the CMEs close
to the Sun because the method does not account for CME over-expansion
in this region. Observed velocities from SSSE are found to agree well
with single-spacecraft (SSEF) analysis techniques applied to the same
events. CME propagation directions derived from SSSE and SSEF analysis
agree poorly because of known limitations present in the latter.

---------------------------------------------------------
Title: The Spectrometer/Telescope for Imaging X-rays (STIX)
Authors: Krucker, Säm; Hurford, G. J.; Grimm, O.; Kögl, S.;
Gröbelbauer, H. -P.; Etesi, L.; Casadei, D.; Csillaghy, A.; Benz,
A. O.; Arnold, N. G.; Molendini, F.; Orleanski, P.; Schori, D.; Xiao,
H.; Kuhar, M.; Hochmuth, N.; Felix, S.; Schramka, F.; Marcin, S.;
Kobler, S.; Iseli, L.; Dreier, M.; Wiehl, H. J.; Kleint, L.; Battaglia,
M.; Lastufka, E.; Sathiapal, H.; Lapadula, K.; Bednarzik, M.; Birrer,
G.; Stutz, St.; Wild, Ch.; Marone, F.; Skup, K. R.; Cichocki, A.; Ber,
K.; Rutkowski, K.; Bujwan, W.; Juchnikowski, G.; Winkler, M.; Darmetko,
M.; Michalska, M.; Seweryn, K.; Białek, A.; Osica, P.; Sylwester, J.;
Kowalinski, M.; Ścisłowski, D.; Siarkowski, M.; Stęślicki, M.;
Mrozek, T.; Podgórski, P.; Meuris, A.; Limousin, O.; Gevin, O.; Le
Mer, I.; Brun, S.; Strugarek, A.; Vilmer, N.; Musset, S.; Maksimović,
M.; Fárník, F.; Kozáček, Z.; Kašparová, J.; Mann, G.; Önel,
H.; Warmuth, A.; Rendtel, J.; Anderson, J.; Bauer, S.; Dionies, F.;
Paschke, J.; Plüschke, D.; Woche, M.; Schuller, F.; Veronig, A. M.;
Dickson, E. C. M.; Gallagher, P. T.; Maloney, S. A.; Bloomfield, D. S.;
Piana, M.; Massone, A. M.; Benvenuto, F.; Massa, P.; Schwartz, R. A.;
Dennis, B. R.; van Beek, H. F.; Rodríguez-Pacheco, J.; Lin, R. P.
2020A&A...642A..15K Altcode:
 Aims: The Spectrometer Telescope for Imaging X-rays (STIX)
on Solar Orbiter is a hard X-ray imaging spectrometer, which
covers the energy range from 4 to 150 keV. STIX observes hard X-ray
bremsstrahlung emissions from solar flares and therefore provides
diagnostics of the hottest (⪆10 MK) flare plasma while quantifying
the location, spectrum, and energy content of flare-accelerated
nonthermal electrons. Methods: To accomplish this, STIX applies
an indirect bigrid Fourier imaging technique using a set of tungsten
grids (at pitches from 0.038 to 1 mm) in front of 32 coarsely pixelated
CdTe detectors to provide information on angular scales from 7 to 180
arcsec with 1 keV energy resolution (at 6 keV). The imaging concept of
STIX has intrinsically low telemetry and it is therefore well-suited
to the limited resources available to the Solar Orbiter payload. To
further reduce the downlinked data volume, STIX data are binned on
board into 32 selectable energy bins and dynamically-adjusted time
bins with a typical duration of 1 s during flares. Results:
Through hard X-ray diagnostics, STIX provides critical information
for understanding the acceleration of electrons at the Sun and their
transport into interplanetary space and for determining the magnetic
connection of Solar Orbiter back to the Sun. In this way, STIX serves
to link Solar Orbiter's remote and in-situ measurements.

---------------------------------------------------------
Title: Statistical Study of GOES X-Ray Quasi-periodic Pulsations in
Solar Flares
Authors: Hayes, L.; Inglis, A.; Christe, S.; Dennis, B.; Gallagher, P.
2020SPD....5121114H Altcode:
Small-amplitude quasi-periodic pulsations (QPPs) detected in soft X-ray
emission are commonplace in many flares. To date, the underpinning
processes resulting in the QPPs are unknown. In this paper, we
attempt to constrain the prevalence of stationary QPPs in the largest
statistical study to date, including a study of the relationship of
QPP periods to the properties of the flaring active region, flare
ribbons, and coronal mass ejection (CME) affiliation. We build upon
the work of Inglis et al. and use a model comparison test to search
for significant power in the Fourier spectra of lightcurves of the
GOES 1-8 Å channel. We analyze all X-, M- and C-class flares of the
past solar cycle, a total of 5519 flares, and search for periodicity
in the 6-300 s timescale range. Approximately 46% of X-class, 29%
of M-class, and 7% of C-class flares show evidence of stationary
QPPs, with periods that follow a log-normal distribution peaked at 20
s. The QPP periods were found to be independent of flare magnitude;
however, a positive correlation was found between QPP period and flare
duration. No dependence of the QPP periods on the global active region
properties was identified. A positive correlation was found between QPPs
and ribbon properties, including unsigned magnetic flux, ribbon area,
and ribbon separation distance. We found that both flares with and
without an associated CME can host QPPs. Furthermore, we demonstrate
that for X- and M-class flares, decay-phase QPPs have statistically
longer periods than impulsive-phase QPPs.

---------------------------------------------------------
Title: Ensemble forecasting of major solar flares: methods for
combining models
Authors: Guerra, Jordan A.; Murray, Sophie A.; Shaun Bloomfield, D.;
Gallagher, Peter T.
2020JSWSC..10...38G Altcode: 2020arXiv200800382G
One essential component of operational space weather forecasting is
the prediction of solar flares. With a multitude of flare forecasting
methods now available online it is still unclear which of these
methods performs best, and none are substantially better than
climatological forecasts. Space weather researchers are increasingly
looking towards methods used by the terrestrial weather community
to improve current forecasting techniques. Ensemble forecasting has
been used in numerical weather prediction for many years as a way
to combine different predictions in order to obtain a more accurate
result. Here we construct ensemble forecasts for major solar flares
by linearly combining the full-disk probabilistic forecasts from a
group of operational forecasting methods (ASAP, ASSA, MAG4, MOSWOC,
NOAA, and MCSTAT). Forecasts from each method are weighted by a
factor that accounts for the method's ability to predict previous
events, and several performance metrics (both probabilistic and
categorical) are considered. It is found that most ensembles achieve
a better skill metric (between 5% and 15%) than any of the members
alone. Moreover, over 90% of ensembles perform better (as measured
by forecast attributes) than a simple equal-weights average. Finally,
ensemble uncertainties are highly dependent on the internal metric being
optimized and they are estimated to be less than 20% for probabilities
greater than 0.2. This simple multi-model, linear ensemble technique
can provide operational space weather centres with the basis for
constructing a versatile ensemble forecasting system - an improved
starting point to their forecasts that can be tailored to different
end-user needs.

---------------------------------------------------------
Title: A New Facility for Airborne Solar Astronomy: NASA's WB-57 at
the 2017 Total Solar Eclipse
Authors: Caspi, Amir; Seaton, Daniel B.; Tsang, Constantine C. C.;
DeForest, Craig E.; Bryans, Paul; DeLuca, Edward E.; Tomczyk,
Steven; Burkepile, Joan T.; Casey, Thomas "Tony"; Collier, John;
Darrow, Donald "DD"; Del Rosso, Dominic; Durda, Daniel D.; Gallagher,
Peter T.; Golub, Leon; Jacyna, Matthew; Johnson, David "DJ"; Judge,
Philip G.; Klemm, Cary "Diddle"; Laurent, Glenn T.; Lewis, Johanna;
Mallini, Charles J.; Parent, Thomas "Duster"; Propp, Timothy; Steffl,
Andrew J.; Warner, Jeff; West, Matthew J.; Wiseman, John; Yates,
Mallory; Zhukov, Andrei N.; NASA WB-57 2017 Eclipse Observing Team
2020ApJ...895..131C Altcode: 2020arXiv200409658C
NASA's WB-57 High Altitude Research Program provides a deployable,
mobile, and stratospheric platform for scientific research. Airborne
platforms are of particular value for making coronal observations
during total solar eclipses because of their ability both to follow the
Moon's shadow and to get above most of the atmospheric air mass that
can interfere with astronomical observations. We used the 2017 August
21 eclipse as a pathfinding mission for high-altitude airborne solar
astronomy, using the existing high-speed visible-light and near/midwave
infrared imaging suite mounted in the WB-57 nose cone. In this paper,
we describe the aircraft, the instrument, and the 2017 mission;
operations and data acquisition; and preliminary analysis of data
quality from the existing instrument suite. We describe benefits and
technical limitations of this platform for solar and other astronomical
observations. We present a preliminary analysis of the visible-light
data quality and discuss the limiting factors that must be overcome
with future instrumentation. We conclude with a discussion of lessons
learned from this pathfinding mission and prospects for future research
at upcoming eclipses, as well as an evaluation of the capabilities of
the WB-57 platform for future solar astronomy and general astronomical
observation.

---------------------------------------------------------
Title: Imaging the Solar Corona during the 2015 March 20 Eclipse
using LOFAR
Authors: Ryan, Aoife Maria; Gallagher, Peter T.; Carley, Eoin P.;
Morosan, Diana E.; Brentjens, Michiel A.; Zucca, Pietro; Fallows,
Richard; Vocks, Christian; Mann, Gottfried; Breitling, Frank;
Magdalenic, Jasmina; Kerdraon, Alain; Reid, Hamish
2020EGUGA..2218173R Altcode:
The solar corona is a highly-structured plasma which reaches
temperatures of more than ~2MK. At low radio frequencies (≤ 400 MHz),
scattering and refraction of electromagnetic waves are thought to
broaden sources to several arcminutes. However, exactly how source
size relates to scattering due to turbulence is still subject
to investigation. This is mainly due to the lack of high spatial
resolution observations of the solar corona at low frequencies. Here,
we use the LOw Frequency ARray (LOFAR) to observe the solar corona
at 120-180 MHz using baselines of up to ~3.5 km (~1--2') during a
partial solar eclipse of 2015 March 20. We use a lunar de-occultation
technique to achieve higher spatial resolution than that attainable via
traditional interferometric imaging. This provides a means of studying
source sizes in the corona that are smaller than the angular width of
the interferometric point spread function.

---------------------------------------------------------
Title: Interferometric Observations of the Active Regions in Radio
Domain Before and After the Total Solar Eclipse on 21 August 2017
Authors: Dabrowski, Bartosz; Flisek, Paweł; Vocks, Christian; Morosan,
Diana; Zhang, Peijin; Zucca, Pietro; Magdalenic, Jasmina; Fallows,
Richard; Krankowski, Andrzej; Mann, Gottfried; Blaszkiewicz, Leszek;
Rudawy, Pawel; Hajduk, Marcin; Fron, Adam; Gallagher, Peter; Ryan,
Aoife Maria; Kotulak, Kacper; Matyjasiak, Barbara
2020EGUGA..22.7374D Altcode:
We hereby present the interferometric LOFAR observations made before and
after the total solar eclipse on 21 August 2017, during which the type
III radio bursts have been detected.The LOw-Frequency ARray (LOFAR)
is a large radio interferometer operating in the frequency range
of 10-240 MHz, designed and constructed by ASTRON (the Netherlands
Institute for Radio Astronomy). The LOFAR telescope is an array of
stations distributed throughout the Netherlands and other parts of
Europe. Currently the system consist of 52 LOFAR stations located
in Europe. Apart from the high time and frequency resolution of the
dynamic spectra, LOFAR allows also a 2D imaging of the radio sources
and tracking of their positions through the solar corona.In this work
we present a preliminary analysis of the dynamic spectra of type III
radio bursts with radio images.

---------------------------------------------------------
Title: Type III Radio Bursts and Langmuir Wave Excitation
Authors: Mann, Gottfried; Vocks, Christian; Bisi, Mario; Carley, Eoin;
Dabrowski, Bartosz; Fallows, Richard; Gallagher, Peter; Krankowski,
Andrzej; Magdalenic, Jasmina; Marque, Christophe; Morosan, Diana;
Rothkaehl, Hanna; Zucca, Pietro
2020EGUGA..22.7595M Altcode:
Type III radio bursts are a common phenomenon the Sun's nonthermal
radio radiation. They appear as stripes of enhanced radio emission
with a rapid drift from high to low frequencies in dynamic radio
spectra. They are considered as the radio signatures of beams of
energetic electrons travelling along magnetic field lines from the
solar corona into the interplanetary space. With the ground based
radio interferometer LOFAR and the instrument FIELDS onboard NASA's
"Parker Solar Probe" (PSP), type III radio bursts can be observed
simultaneously from high (10-240 MHz) to low frequencies (0.01-20 MHz)
with LOFAR and PSP's FIELDs, respectively. That allows to track these
electron beams from the corona up to the interplanetary space. Assuming
that a population of energetic electrons is initially injected,
the velocity distribution function of these electrons evolves into a
beam like one. Such distribution function leads to the excitation of
Langmuir waves which convert into radio waves finally observed as type
II radio bursts. Numerical calculations of the electron-beam-plasma
interaction reveal that the Langmuir waves are excited by different
parts of the energetic electrons at different distances in the corona
and interplanetary space. This result is compared with special type
III radio bursts observed with LOFAR and PSP's FIELDS.

---------------------------------------------------------
Title: Evolution of the Alfvén Mach number associated with a coronal
mass ejection shock
Authors: Maguire, Ciara; Carley, Eoin; McCauley, Joseph; Gallagher,
Peter
2020EGUGA..2211425M Altcode:
The Sun regularly produces large-scale eruptive events, such as coronal
mass ejections (CMEs) that can drive shock waves through the solar
corona. Such shocks can result in electron acceleration and subsequent
radio emission in the form of a type II radio burst. However, the
early-phase evolution of shock properties and its relationship to
type II burst evolution is still subject to investigation. Here we
study the evolution of a CME-driven shock by comparing three commonly
used methods of calculating the Alfvén Mach number (MA), namely:
shock geometry, a comparison of CME speed to a model of the coronal
Alfvén speed, and the type II band-splitting method. We applied the
three methods to the 2017 September 2 event, focusing on the shock
wave observed in extreme ultraviolet (EUV) by the Solar Ultraviolet
Imager (SUVI) on board GOES-16, in white-light by the Large Angle
and Spectrometric Coronagraph (LASCO) on board SOHO, and the type II
radio burst observed by the Irish Low Frequency Array (I-LOFAR). We
show that the three different methods of estimating shock MA yield
consistent results and provide a means of relating shock property
evolution to the type II emission duration. The type II radio emission
emerged from near the nose of the CME when MA was in the range 1.4-2.4
at a heliocentric distance of ∼1.6 R⊙. The emission ceased when
the CME nose reached ∼2.4 R⊙, despite an increasing Alfvén Mach
number (up to 4). We suggest the radio emission cessation is due to the
lack of quasi-perpendicular geometry at this altitude, which inhibits
efficient electron acceleration and subsequent radio emission.

---------------------------------------------------------
Title: Statistical Study of GOES X-Ray Quasi-periodic Pulsations in
Solar Flares
Authors: Hayes, Laura A.; Inglis, Andrew R.; Christe, Steven; Dennis,
Brian; Gallagher, Peter T.
2020ApJ...895...50H Altcode: 2020arXiv200411775H
Small-amplitude quasi-periodic pulsations (QPPs) detected in soft X-ray
emission are commonplace in many flares. To date, the underpinning
processes resulting in the QPPs are unknown. In this paper, we
attempt to constrain the prevalence of stationary QPPs in the largest
statistical study to date, including a study of the relationship of
QPP periods to the properties of the flaring active region, flare
ribbons, and coronal mass ejection (CME) affiliation. We build upon
the work of Inglis et al. and use a model comparison test to search
for significant power in the Fourier spectra of lightcurves of the
GOES 1-8 Å channel. We analyze all X-, M- and C-class flares of the
past solar cycle, a total of 5519 flares, and search for periodicity
in the 6-300 s timescale range. Approximately 46% of X-class, 29%
of M-class, and 7% of C-class flares show evidence of stationary
QPPs, with periods that follow a log-normal distribution peaked at 20
s. The QPP periods were found to be independent of flare magnitude;
however, a positive correlation was found between QPP period and flare
duration. No dependence of the QPP periods on the global active region
properties was identified. A positive correlation was found between QPPs
and ribbon properties, including unsigned magnetic flux, ribbon area,
and ribbon separation distance. We found that both flares with and
without an associated CME can host QPPs. Furthermore, we demonstrate
that for X- and M-class flares, decay-phase QPPs have statistically
longer periods than impulsive-phase QPPs.

---------------------------------------------------------
Title: LOFAR4SpaceWeather (LOFAR4SW) - Increasing European
Space-Weather Capability with Europe's Largest Radio Telescope:
Beyond the Detailed Design Review (DDR)
Authors: Bisi, Mario M.; Ruiter, Mark; Fallows, Richard A.; Vermeulen,
René; Robertson, Stuart C.; Vilmer, Nicole; Rothkaehl, Hanna;
Matyjasiak, Barbara; Verbiest, Joris; Gallagher, Peter T.; Olberg,
Michael; Carozzi, Tobia; Lindqvist, Michael; Carley, Eoin; Krüger,
Paulus; Mevius, Maaijke; Baldovin, Carla; Barnes, David
2020EGUGA..2214948B Altcode:
The Low Frequency Array (LOFAR) is an advanced phased-array
radio-telescope system based across Europe. It is capable of observing
over a wide radio bandwidth of ~10-250 MHz at both high spatial and
temporal resolutions. LOFAR has capabilities that enable studies of many
aspects of what we class as space weather (from the Sun to the Earth
and afar) to be progressed beyond today's state-of-the-art. However,
with the present setup and organisation behind the operations
of the telescope, it can only be used for space-weather campaign
studies with limited triggering availability. This severely limits
our ability to effectively use LOFAR to contribute to space-weather
monitoring/forecast beyond its core strength of enabling world-leading
scientific research. LOFAR itself is made up of a dense core of
24 stations near Exloo in The Netherlands with an additional 14
stations spread across the northeast Netherlands. In addition to
those, there are a further 13 stations based internationally across
Europe. These international stations are, currently, six in Germany,
three in northern Poland, and one each in France, Ireland, Latvia,
Sweden, and the UK. Further sites are under preparations (for example,
in Italy). We are undertaking a Horizon 2020 (H2020) INFRADEV design
study to undertake investigations into upgrading LOFAR to allow for
regular space-weather science/monitoring observations in parallel
with normal radio-astronomy/scientific operations. This project
is called the LOFAR For Space Weather (LOFAR4SW) project (see:
http://lofar4sw.eu/). Our work involves all aspects of scientific
and engineering work along with end-user and political engagements
with various stakeholders. This is with the full recognition that
space weather is a worldwide threat with varying local, regional,
continent-wide impacts, and also global impacts - and hence is a global
concern. Here, we summarise the most-recent key aspects of the LOFAR4SW
progress including outputs/progress following the Detailed Design Review
(DDR) that took place at ASTRON, The Netherlands, in March 2020,
as well as the implementation of recommendations from the earlier
Preliminary Design Review (PDR) with an outlook to the LOFAR4SW User
Workshop the week following EGU 2020. We also aim to briefly summarise
a key set of the longer-term goals envisaged for LOFAR to become one
of Europe's most-comprehensive space-weather observing systems capable
of shedding new light on several aspects of the space-weather system,
from the Sun to the solar wind to Jupiter and Earth's ionosphere.

---------------------------------------------------------
Title: A Comparison of Flare Forecasting Methods. IV. Evaluating
Consecutive-day Forecasting Patterns
Authors: Park, Sung-Hong; Leka, K. D.; Kusano, Kanya; Andries, Jesse;
Barnes, Graham; Bingham, Suzy; Bloomfield, D. Shaun; McCloskey,
Aoife E.; Delouille, Veronique; Falconer, David; Gallagher, Peter T.;
Georgoulis, Manolis K.; Kubo, Yuki; Lee, Kangjin; Lee, Sangwoo; Lobzin,
Vasily; Mun, JunChul; Murray, Sophie A.; Hamad Nageem, Tarek A. M.;
Qahwaji, Rami; Sharpe, Michael; Steenburgh, R. A.; Steward, Graham;
Terkildsen, Michael
2020ApJ...890..124P Altcode: 2020arXiv200102808P
A crucial challenge to successful flare prediction is
forecasting periods that transition between "flare-quiet" and
"flare-active." Building on earlier studies in this series in which we
describe the methodology, details, and results of flare forecasting
comparison efforts, we focus here on patterns of forecast outcomes
(success and failure) over multiday periods. A novel analysis is
developed to evaluate forecasting success in the context of catching
the first event of flare-active periods and, conversely, correctly
predicting declining flare activity. We demonstrate these evaluation
methods graphically and quantitatively as they provide both quick
comparative evaluations and options for detailed analysis. For the
testing interval 2016-2017, we determine the relative frequency
distribution of two-day dichotomous forecast outcomes for three
different event histories (I.e., event/event, no-event/event, and
event/no-event) and use it to highlight performance differences between
forecasting methods. A trend is identified across all forecasting
methods that a high/low forecast probability on day 1 remains high/low
on day 2, even though flaring activity is transitioning. For M-class
and larger flares, we find that explicitly including persistence or
prior flare history in computing forecasts helps to improve overall
forecast performance. It is also found that using magnetic/modern
data leads to improvement in catching the first-event/first-no-event
transitions. Finally, 15% of major (I.e., M-class or above) flare
days over the testing interval were effectively missed due to a lack
of observations from instruments away from the Earth-Sun line.

---------------------------------------------------------
Title: The Effect of the 21 August 2017 Total Solar Eclipse on the
Phase of VLF/LF Signals
Authors: Rozhnoi, A.; Solovieva, M.; Shalimov, S.; Ouzounov, D.;
Gallagher, P.; Verth, G.; McCauley, J.; Shelyag, S.; Fedun, V.
2020E&SS....700839R Altcode:
An experimental study of the phase and amplitude observations
of sub-ionospheric very low and low frequency (VLF/LF) signals is
performed to analyze the response of the lower ionosphere during the 21
August 2017 total solar eclipse in the United States of America. Three
different sub-ionospheric wave paths are investigated. The length of
the paths varies from 2,200 to 6,400 km, and the signal frequencies
are 21.4, 25.2, and 40.75 kHz. The two paths cross the region of
the total eclipse, and the third path is in the region of 40-60%
of obscuration. None of the signals reveal any noticeable amplitude
changes during the eclipse, while negative phase anomalies (from
-33° to -95°) are detected for all three paths. It is shown that
the effective reflection height of the ionosphere in low and middle
latitudes is increased by about 3-5 km during the eclipse. Estimation
of the electron density change in the lower ionosphere caused by
the eclipse, using linear recombination law, shows that the average
decrease is by 2.1 to 4.5 times.

---------------------------------------------------------
Title: Evolution of the Alfvén Mach number associated with a coronal
mass ejection shock
Authors: Maguire, Ciara A.; Carley, Eoin P.; McCauley, Joseph;
Gallagher, Peter T.
2020A&A...633A..56M Altcode: 2019arXiv191201863M
The Sun regularly produces large-scale eruptive events, such as coronal
mass ejections (CMEs) that can drive shock waves through the solar
corona. Such shocks can result in electron acceleration and subsequent
radio emission in the form of a type II radio burst. However, the
early-phase evolution of shock properties and its relationship to type
II burst evolution is still subject to investigation. Here we study
the evolution of a CME-driven shock by comparing three commonly used
methods of calculating the Alfvén Mach number (MA), namely:
shock geometry, a comparison of CME speed to a model of the coronal
Alfvén speed, and the type II band-splitting method. We applied the
three methods to the 2017 September 2 event, focusing on the shock
wave observed in extreme ultraviolet by the Solar Ultraviolet Imager
on board GOES-16, in white-light by the Large Angle and Spectrometric
Coronagraph on board SOHO, and the type II radio burst observed by the
Irish Low Frequency Array. We show that the three different methods of
estimating shock MA yield consistent results and provide
a means of relating shock property evolution to the type II emission
duration. The type II radio emission emerged from near the nose of
the CME when MA was in the range 1.4-2.4 at a heliocentric
distance of ∼1.6 R⊙. The emission ceased when the CME
nose reached ∼2.4 R⊙, despite an increasing Alfvén
Mach number (up to 4). We suggest the radio emission cessation is due
to the lack of quasi-perpendicular geometry at this altitude, which
inhibits efficient electron acceleration and subsequent radio emission.

---------------------------------------------------------
Title: Radio observatories and instrumentation used in space weather
science and operations
Authors: Carley, Eoin P.; Baldovin, Carla; Benthem, Pieter; Bisi,
Mario M.; Fallows, Richard A.; Gallagher, Peter T.; Olberg, Michael;
Rothkaehl, Hanna; Vermeulen, Rene; Vilmer, Nicole; Barnes, David
2020JSWSC..10....7C Altcode:
The low frequency array (LOFAR) is a phased array interferometer
currently consisting of 13 international stations across Europe and 38
stations surrounding a central hub in the Netherlands. The instrument
operates in the frequency range of ~10-240 MHz and is used for a variety
of astrophysical science cases. While it is not heliophysics or space
weather dedicated, a new project entitled "LOFAR for Space Weather"
(LOFAR4SW) aims at designing a system upgrade to allow the entire
array to observe the Sun, heliosphere, Earth's ionosphere, and Jupiter
throughout its observing window. This will allow the instrument to
operate as a space weather observing platform, facilitating both space
weather science and operations. Part of this design study aims to survey
the existing space weather infrastructure operating at radio frequencies
and show how LOFAR4SW can advance the current state-of-the-art in this
field. In this paper, we survey radio instrumentation and facilities
that currently operate in space weather science and/or operations,
including instruments involved in solar, heliospheric, and ionospheric
studies. We furthermore include an overview of the major space weather
service providers in operation today and the current state-of-the-art
in the radio data they use and provide routinely. The aim is to compare
LOFAR4SW to the existing radio research infrastructure in space weather
and show how it may advance both space weather science and operations
in the radio domain in the near future.

---------------------------------------------------------
Title: Novel observations of the middle corona during the 2017 total
solar eclipse
Authors: Caspi, A.; Seaton, D. B.; Tsang, C.; DeForest, C.; Bryans,
P.; Samra, J.; DeLuca, E.; Tomczyk, S.; Burkepile, J.; Gallagher,
P.; Golub, L.; Judge, P. G.; Laurent, G. T.; West, M.; Zhukov, A.
2019AGUFMSH13A..10C Altcode:
Total solar eclipses offer rare opportunities to study the middle
corona. This intriguing region contains complex interfaces and
transitions between physical regimes, but has historically been
under-observed due to the challenges of observing its dim emission so
close to the bright inner corona and blinding solar disk. The unique
circumstances of a total solar eclipse coupled with a high-altitude
observing platform provide nearly space-quality observing conditions,
including for wavelengths inaccessible by ground-based observatories,
but with availability of ground-quality resources, including high-speed,
high-resolution, wide-field coronography typically inaccessible
from space. We used the 2017 August 21 "Great American" total solar
eclipse to observe the solar corona from ~1.02 to ~3 RSun
in both visible (533.9 ± 4.75 nm) and medium-wave infrared (3-5
μm) light using stabilized telescopes on two of NASA's WB-57F
high-altitude research aircraft. This pathfinding mission utilized
existing instrumentation to evaluate the platform performance, guide
instrumentation development, and explore new discovery space for
future studies of the middle corona. We present the high-speed
(30 Hz), high-resolution (3 arcsec/pixel) visible and IR observations
obtained during the eclipse, and analysis of these observations
in the context of coronal structure and dynamics. We discuss the
limitations of the prototype data and pathways forward for future
instrumentation and missions optimized for the range of observable
parameters in the middle corona. We also discuss the benefits of
such eclipse studies to an understanding of the corona as a single,
unified system, from its origins at the solar surface to its extension
into the heliosphere, particularly within the context of a developing
multi- and inter-disciplinary research collaboration, COHERENT (the
"Corona as a Holistic Environment" Research Network).

---------------------------------------------------------
Title: The Breakthrough Listen Search for Extraterrestrial
Intelligence
Authors: Gajjar, Vishal; Siemion, Andrew; Croft, Steve; Brzycki, Bryan;
Burgay, Marta; Carozzi, Tobia; Concu, Raimondo; Czech, Daniel; DeBoer,
David; DeMarines, Julia; Drew, Jamie; Enriquez, J. Emilio; Fawcett,
James; Gallagher, Peter; Gerret, Michael; Gizani, Nectaria; Hellbourg,
Greg; Holder, Jamie; Isaacson, Howard; Kudale, Sanjay; Lacki, Brian;
Lebofsky, Matthew; Li, Di; MacMahon, David H. E.; McCauley, Joe;
Melis, Andrea; Molinari, Emilio; Murphy, Pearse; Perrodin, Delphine;
Pilia, Maura; Price, Danny C.; Webb, Claire; Werthimer, Dan; Williams,
David; Worden, Pete; Zarka, Philippe; Zhang, Yunfan Gerry
2019BAAS...51g.223G Altcode: 2019astro2020U.223G; 2019arXiv190705519G
In this white paper, we outline the status of the on-going observing
campaign with our primary and collaborative observing facilities, as
well as planned activities with these instruments over the next few
years with the Breakthrough Listen program for the technosignature
searches.

---------------------------------------------------------
Title: A Comparison of Flare Forecasting Methods. III. Systematic
Behaviors of Operational Solar Flare Forecasting Systems
Authors: Leka, K. D.; Park, Sung-Hong; Kusano, Kanya; Andries, Jesse;
Barnes, Graham; Bingham, Suzy; Bloomfield, D. Shaun; McCloskey,
Aoife E.; Delouille, Veronique; Falconer, David; Gallagher, Peter
T.; Georgoulis, Manolis K.; Kubo, Yuki; Lee, Kangjin; Lee, Sangwoo;
Lobzin, Vasily; Mun, JunChul; Murray, Sophie A.; Hamad Nageem, Tarek
A. M.; Qahwaji, Rami; Sharpe, Michael; Steenburgh, Robert A.; Steward,
Graham; Terkildsen, Michael
2019ApJ...881..101L Altcode: 2019arXiv190702909L
A workshop was recently held at Nagoya University (2017 October
31-November 2), sponsored by the Center for International Collaborative
Research, at the Institute for Space-Earth Environmental Research,
Nagoya University, Japan, to quantitatively compare the performance
of today’s operational solar flare forecasting facilities. Building
upon Paper I of this series, in Paper II we described the participating
methods for this latest comparison effort, the evaluation methodology,
and presented quantitative comparisons. In this paper, we focus on
the behavior and performance of the methods when evaluated in the
context of broad implementation differences. Acknowledging the short
testing interval available and the small number of methods available,
we do find that forecast performance: (1) appears to improve by
including persistence or prior flare activity, region evolution,
and a human “forecaster in the loop” (2) is hurt by restricting
data to disk-center observations; (3) may benefit from long-term
statistics but mostly when then combined with modern data sources
and statistical approaches. These trends are arguably weak and must
be viewed with numerous caveats, as discussed both here and in Paper
II. Following this present work, in Paper IV (Park et al. 2019) we
will present a novel analysis method to evaluate temporal patterns of
forecasting errors of both types (i.e., misses and false alarms). Hence,
most importantly, with this series of papers, we demonstrate the
techniques for facilitating comparisons in the interest of establishing
performance-positive methodologies.

---------------------------------------------------------
Title: A Comparison of Flare Forecasting Methods. II. Benchmarks,
Metrics, and Performance Results for Operational Solar Flare
Forecasting Systems
Authors: Leka, K. D.; Park, Sung-Hong; Kusano, Kanya; Andries, Jesse;
Barnes, Graham; Bingham, Suzy; Bloomfield, D. Shaun; McCloskey,
Aoife E.; Delouille, Veronique; Falconer, David; Gallagher, Peter
T.; Georgoulis, Manolis K.; Kubo, Yuki; Lee, Kangjin; Lee, Sangwoo;
Lobzin, Vasily; Mun, JunChul; Murray, Sophie A.; Hamad Nageem, Tarek
A. M.; Qahwaji, Rami; Sharpe, Michael; Steenburgh, Robert A.; Steward,
Graham; Terkildsen, Michael
2019ApJS..243...36L Altcode: 2019arXiv190702905L
Solar flares are extremely energetic phenomena in our solar
system. Their impulsive and often drastic radiative increases,
particularly at short wavelengths, bring immediate impacts that motivate
solar physics and space weather research to understand solar flares
to the point of being able to forecast them. As data and algorithms
improve dramatically, questions must be asked concerning how well the
forecasting performs; crucially, we must ask how to rigorously measure
performance in order to critically gauge any improvements. Building
upon earlier-developed methodology of Paper I (Barnes et al. 2016),
international representatives of regional warning centers and
research facilities assembled in 2017 at the Institute for Space-Earth
Environmental Research, Nagoya University, Japan to, for the first time,
directly compare the performance of operational solar flare forecasting
methods. Multiple quantitative evaluation metrics are employed, with the
focus and discussion on evaluation methodologies given the restrictions
of operational forecasting. Numerous methods performed consistently
above the “no-skill” level, although which method scored top marks
is decisively a function of flare event definition and the metric
used; there was no single winner. Following in this paper series, we
ask why the performances differ by examining implementation details
(Leka et al. 2019), and then we present a novel analysis method to
evaluate temporal patterns of forecasting errors in Paper IV (Park
et al. 2019). With these works, this team presents a well-defined and
robust methodology for evaluating solar flare forecasting methods in
both research and operational frameworks and today’s performance
benchmarks against which improvements and new methods may be compared.

---------------------------------------------------------
Title: Temporal, Spectral and Spatial Analysis of Flaring
Quasi-Periodic Pulsations
Authors: Hayes, Laura A.; Gallagher, Peter; Christe, Steven; Dennis,
Brian R.
2019AAS...23422505H Altcode:
One of the key observational features in flaring emission associated
with accelerated electrons is the presence of pronounced modulations
and oscillatory signatures known as quasi-periodic pulsations
(QPPs). To date, the underpinning mechanisms resulting in the
emission modulation remains unknown, and detailed multi-wavelength
investigations of flaring QPP events are required to identify the
modulation process. Here we will present a detailed temporal, spectral
and spatially-resolved investigation of the X1.2 solar flare from May
15 2013 that demonstrate large modulations in its emission. During
the impulsive phase, pronounced QPPs with a period of 50s are observed
across multiple wavebands including hard and soft X-rays, microwave,
UV, EUV - essentially across the whole flaring region. We examine the
modulation amplitudes of the different emissions, and in particular
focus on the hard X-ray and microwave spectral indices and on the
modulation of the degree of polarization of the radio emissions. To
further constrain the potential QPP mechanism, we analyse spatially
resolved observations of the non-thermal pulsations using both
RHESSI and Nobeyama RadioHeliograph data to probe the locations of
where the QPP emission is occurring. The results are suggestive of a
trap-plus-precipitation model. We will also discuss the QPP modulation
in relation to the observed CME eruption. The current theories to
explain the presence of QPPs in the context of this event will be
presented, along with a discussion of how this type of analysis can
be further utilized to probe the mechanisms for electron acceleration
and plasma heating.

---------------------------------------------------------
Title: CMEs in the Heliosphere: II. A Statistical Analysis of the
Kinematic Properties Derived from Single-Spacecraft Geometrical
Modelling Techniques Applied to CMEs Detected in the Heliosphere
from 2007 to 2017 by STEREO/HI-1
Authors: Barnes, D.; Davies, J. A.; Harrison, R. A.; Byrne, J. P.;
Perry, C. H.; Bothmer, V.; Eastwood, J. P.; Gallagher, P. T.; Kilpua,
E. K. J.; Möstl, C.; Rodriguez, L.; Rouillard, A. P.; Odstrčil, D.
2019SoPh..294...57B Altcode:
Recent observations with the Heliospheric Imagers (HIs) onboard the twin
NASA Solar Terrestrial Relations Observatory (STEREO) spacecraft have
provided unprecedented observations of a large number of coronal mass
ejections (CMEs) in the inner heliosphere. In this article we discuss
the generation of the HIGeoCAT CME catalogue and perform a statistical
analysis of its events. The catalogue was generated as part of the
EU FP7 HELCATS (Heliospheric Cataloguing, Analysis and Techniques
Service) project (www.helcats-fp7.eu/). It is created by generating
time/elongation maps for CMEs using observations from the inner (HI-1)
and outer (HI-2) cameras along a position angle close to the CME
apex. Next, we apply single-spacecraft geometric-fitting techniques
to determine the kinematic properties of these CMEs, including their
speeds, propagation directions, and launch times. The catalogue contains
a total of 1455 events (801 from STEREO-A and 654 from STEREO-B)
from April 2007 to the end of August 2017. We perform a statistical
analysis of the properties of CMEs in HIGeoCAT and compare the results
with those from the Large Angle Spectrometric Coronagraph (LASCO) CDAW
catalogues (Yashiro et al.J. Geophys. Res. Space Phys.109, A07105,
2004) and the COR-2 catalogue of Vourlidas et al. (Astrophys. J.838,
141, 2004) during the same period. We find that the distributions of
both speeds and latitudes for the HIGeoCAT CMEs correlate with the
sunspot number over the solar cycle. We also find that the HI-derived
CME speed distributions are generally consistent with coronagraph
catalogues over the solar cycle, albeit with greater absolute speeds
due to the differing methods with which each is derived.

---------------------------------------------------------
Title: LOFAR For Space Weather (LOFAR4SW): Increasing European
Space-Weather Capability with Europe's Largest Radio Telescope
Authors: Bisi, Mario M.; Vermeulen, René; Fallows, Richard A.;
Benthem, Pieter; Vilmer, Nicole; Rothkaehl, Hanna; Matyjasiak, Barbara;
Verbiest, Joris; Gallagher, Peter T.; Carley, Eoin; Olberg, Michael;
Mevius, Maaijke; Robertson, Stuart C.; Barnes, David
2019shin.confE.229B Altcode:
The Low Frequency Array (LOFAR) consists of a dense core of 24 stations
within a 4km diameter, 14 stations spread further afield across the
northeast area of The Netherlands, and a further 13 stations spread
internationally (six across Germany, three in northern Poland, and one
each in France, Ireland, Sweden, and the UK). Further international
expansion is under way. LOFAR observes over a wide bandwidth
in radio frequencies (10-250 MHz) with both a high temporal and
spatial resolution. LOFAR is one of the world’s most-flexible radio
instruments with capabilities that enable studies of several aspects of
space weather to be progressed beyond today’s state-of-the-art. However, in its present setup, LOFAR can only be used for
space-weather purposes on a campaign bases of observations. This is
where observing time has to be competed for alongside astronomy and all
other types of radio observations requested. The LOFAR For Space
Weather (LOFAR4SW) project is a Horizon 2020 (H2020) INFRADEV design
study undertaking investigations/design steps into upgrading LOFAR to
allow for regular space-weather monitoring observations in parallel with
normal radio-astronomy and scientific operations. A fully-implemented
LOFAR4SW system would include a wide range of observational capabilities
covering the Sun, corona, inner heliosphere, Earth’s ionosphere,
Jupiter, heliosphere-planetary interactions, and potentially extra-solar
space weather on a routine/regular basis adding to our knowledge,
understanding, and prediction capabilities of space weather - a global
threat. In this presentation, we summarise the LOFAR4SW design
study, progress to date post-Preliminary Design Review and pre-Mid-Term
Review, and some of the longer-term goals envisaged for LOFAR to become
one of Europe’s most-comprehensive space-weather observatories,
shedding new light on several aspects of the space-weather system,
from the Sun to the solar wind to the ionosphere.

---------------------------------------------------------
Title: Loss-cone instability modulation due to a magnetohydrodynamic
sausage mode oscillation in the solar corona
Authors: Carley, Eoin P.; Hayes, Laura A.; Murray, Sophie A.; Morosan,
Diana E.; Shelley, Warren; Vilmer, Nicole; Gallagher, Peter T.
2019NatCo..10.2276C Altcode:
Solar flares often involve the acceleration of particles to
relativistic energies and the generation of high-intensity bursts
of radio emission. In some cases, the radio bursts can show periodic
or quasiperiodic intensity pulsations. However, precisely how these
pulsations are generated is still subject to debate. Prominent
theories employ mechanisms such as periodic magnetic reconnection,
magnetohydrodynamic (MHD) oscillations, or some combination of
both. Here we report on high-cadence (0.25 s) radio imaging of a
228 MHz radio source pulsating with a period of 2.3 s during a solar
flare on 2014-April-18. The pulsating source is due to an MHD sausage
mode oscillation periodically triggering electron acceleration in the
corona. The periodic electron acceleration results in the modulation
of a loss-cone instability, ultimately resulting in pulsating
plasma emission. The results show that a complex combination of MHD
oscillations and plasma instability modulation can lead to pulsating
radio emission in astrophysical environments.

---------------------------------------------------------
Title: Persistent Quasi-periodic Pulsations during a Large X-class
Solar Flare
Authors: Hayes, Laura A.; Gallagher, Peter T.; Dennis, Brian R.;
Ireland, Jack; Inglis, Andrew; Morosan, Diana E.
2019ApJ...875...33H Altcode: 2019arXiv190301328H
Solar flares often display pulsating and oscillatory signatures in the
emission, known as quasi-periodic pulsations (QPP). QPP are typically
identified during the impulsive phase of flares, yet in some cases,
their presence is detected late into the decay phase. Here, we report
extensive fine structure QPP that are detected throughout the large X8.2
flare from 2017 September 10. Following the analysis of the thermal
pulsations observed in the Geostationary Operational Environmental
Satellite/X-ray sensor and the 131 Å channel of Solar Dynamics
Observatory/Atmospheric Imaging Assembly, we find a pulsation period of
∼65 s during the impulsive phase followed by lower amplitude QPP with
a period of ∼150 s in the decay phase, up to three hours after the
peak of the flare. We find that during the time of the impulsive QPP,
the soft X-ray source observed with the Reuven Ramaty High Energy Solar
Spectroscopic Imager rapidly rises at a velocity of approximately 17 km
s-1 following the plasmoid/coronal mass ejection eruption. We
interpret these QPP in terms of a manifestation of the reconnection
dynamics in the eruptive event. During the long-duration decay phase
lasting several hours, extended downward contractions of collapsing
loops/plasmoids that reach the top of the flare arcade are observed
in EUV. We note that the existence of persistent QPP into the decay
phase of this flare are most likely related to these features. The
QPP during this phase are discussed in terms of magnetohydrodynamic
wave modes triggered in the post-flaring loops.

---------------------------------------------------------
Title: LOFAR4SW: New capability for Space Weather science by radio
diagnostic.
Authors: Rothkaehl, Hanna; Vermeulen, Rene; Fallows, Richard; Verbiest,
Joris; Vilmer, Nicole; Olberg, Michael; Bisi, Mario; Gallagher, Peter;
Matyjasiak, Barbara; Carley, Eoin; Carozzi, Tobia; Robertson, Stuart
2019EGUGA..21.7679R Altcode:
The Low Frequency Array (LOFAR) telescope is one of the world's
leading radio astronomical instruments which advantage was already
proven by many key science findings. Its wide application in many
domains, not limited only to astronomy, is used by scientists around
the world. LOFAR covers a wide range of low radio frequencies, between
10 and 250 MHz, and has a spatial resolution better than 1 arcsec. The
construction of the telescope enables both interferometric imaging
as well as observations using the formation of multiple sensitive,
narrow beams. The current LOFAR infrastructure, however, allows only
to monitor and investigate the Space Weather conditions. A step towards
preparing the instrument for full Space weather services and providing
high-quality data for forecasting is the LOFAR for Space Weather
(LOFAR4SW) project. LOFAR4SW is an international Horizon 2020 (H2020)
INFRADEV design study, started December 2017 the aim of which is to
deliver the full conceptual and technical design for creating a new
leading-edge European research facility for space weather science. A
fully-implemented LOFAR4SW system will enable a wide range of solar
and space weather research topics to be tackled and have unique
strengths in several high-impact science areas: tracing the initial
launch of a CME; detailed tracking of the solar wind and CMEs through
interplanetary space; in-depth studies of micro- structure in the
Earth's ionosphere. This facility will uniquely provide the missing link
of measurements of the interplanetary magnetic field on global scales -
a key parameter in forecasting the severity of geomagnetic storm on
Earth. The aim of the presentation is to show the science cases on
which emphasis will be placed in the designed LOFAR4SW facility.

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Title: Multiple regions of shock-accelerated particles during a
solar coronal mass ejection
Authors: Morosan, Diana E.; Carley, Eoin P.; Hayes, Laura A.; Murray,
Sophie A.; Zucca, Pietro; Fallows, Richard A.; McCauley, Joe; Kilpua,
Emilia K. J.; Mann, Gottfried; Vocks, Christian; Gallagher, Peter T.
2019NatAs...3..452M Altcode: 2019NatAs.tmp..210M; 2019arXiv190811743M; 2019NatAs.tmp..252M
The Sun is an active star that can launch large eruptions of
magnetized plasma into the heliosphere, known as coronal mass
ejections (CMEs). These can drive shocks that accelerate particles to
high energies, often resulting in radio emission at low frequencies
(&lt;200 MHz). So far, the relationship between the expansion of CMEs,
shocks and particle acceleration is not well understood, partly due
to the lack of radio imaging at low frequencies during the onset
of shock-producing CMEs. Here, we report multi-instrument radio,
white-light and ultraviolet imaging of the second largest flare in
solar cycle 24 (2008-present) and its associated fast CME (3,038 ±
288 km s-1). We identify the location of a multitude of
radio shock signatures, called herringbones, and find evidence for
shock-accelerated electron beams at multiple locations along the
expanding CME. These observations support theories of non-uniform,
rippled shock fronts driven by an expanding CME in the solar corona.

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Title: Properties and magnetic origins of solar S-bursts
Authors: Clarke, Brendan P.; Morosan, Diana E.; Gallagher, Peter T.;
Dorovskyy, Vladimir V.; Konovalenko, Alexander A.; Carley, Eoin P.
2019A&A...622A.204C Altcode: 2019arXiv190107424C
Context. Solar activity is often accompanied by solar radio emission,
consisting of numerous types of solar radio bursts. At low frequencies
(&lt;100 MHz) radio bursts with short durations of milliseconds, such
as solar S-bursts, have been identified. To date, their origin and
many of their characteristics remain unclear. Aims: We report
observations from the Ukrainian T-shaped Radio telescope, (UTR-2),
and the LOw Frequency ARray (LOFAR) which give us new insight into
their nature. Methods: Over 3000 S-bursts were observed on
9 July 2013 at frequencies of 17.4-83.1 MHz during a period of low
solar activity. Leading models of S-burst generation were tested by
analysing the spectral properties of S-bursts and estimating coronal
magnetic field strengths. Results: S-bursts were found to have
short durations of 0.5-0.9 s. Multiple instruments were used to measure
the dependence of drift rate on frequency which is represented by a
power law with an index of 1.57. For the first time, we show a linear
relation between instantaneous bandwidth and frequency over a wide
frequency band. The flux calibration and high sensitivity of UTR-2
enabled measurements of their fluxes, which yielded 11 ± 3 solar flux
units (1 SFU ≡ 104 Jy). The source particle velocities of
S-bursts were found to be ∼0.07 c. S-burst source heights were found
to range from 1.3 R⊙ to 2 R⊙. Furthermore,
a contemporary theoretical model of S-burst generation was used to
conduct remote sensing of the coronal magnetic field at these heights
which yielded values of 0.9-5.8 G. Within error, these values are
comparable to those predicted by various relations between magnetic
field strength and height in the corona.

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Title: Expansion of High-speed Solar Wind Streams from Coronal Holes
through the Inner Heliosphere
Authors: Garton, Tadhg M.; Murray, Sophie A.; Gallagher, Peter T.
2018ApJ...869L..12G Altcode: 2018arXiv181111605G
Coronal holes (CHs) are regions of open magnetic flux that are the
source of high-speed solar wind (HSSW) streams. To date, it is not clear
which aspects of CHs exert the most influence on the properties of
the solar wind as it expands through the Heliosphere. Here, we study
the relationship between CH properties extracted from Atmospheric
Imaging Assembly images using the Coronal Hole Identification via
Multi-thermal Emission Recognition Algorithm and HSSW measurements from
Advanced Composition Explorer at L1. For CH longitudinal widths Δθ
CH &lt; 67°, the peak solar wind velocity (v max)
is found to scale as v max ≈ 330.8 + 5.7 Δθ CH
km s-1. For larger longitudinal widths (Δθ CH
&gt; 67°), v max is found to tend to a constant value
(∼710 km s-1). Furthermore, we find that the duration
of HSSW streams (Δt) are directly related to the longitudinal width
of CHs (Δt SW ≈ 0.09Δθ CH) and that their
longitudinal expansion factor is f SW ≈ 1.2 ± 0.1. We
also derive an expression for the CH flux-tube expansion factor, f
FT, which varies as f SW ≳ f FT ≳
0.8. These results enable us to estimate the peak speeds and durations
of HSSW streams at L1 using the properties of CHs identified in the
solar corona.

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Title: Sunspot Group Classification using Neural Networks
Authors: Maloney, S. A.; Gallagher, P. T.
2018csc..confE..92M Altcode:
Sunspots are the sources of the most extreme and potentially adverse
solar events such as flares and CMEs. As such many forecasting systems
have been developed to predict these events, a number of which rely
on sunspot group classifications. The classifications are manually
produced so are subject to human errors and biases. Additionally,
as the classifications are only produced on a daily basis this
limits the time resolution of some forecasting methods. Further
with the imaging cadence of SDO HMI, it would be impossible for a
human to produce classifications for every observation. As such the
development of an automated classification system would provide many
benefits. Neural networks (NNs) have proven to be powerful tools
for solving many complex problems such as classification, regression,
and optimisation. In particular, the application of convolutional
neural networks (CNNs) to image classification has greatly improved the
performance of such systems. The first example of this, in the 1990s,
was the identification of handwritten digits from 646 checks an 82%
accuracy was achieved. Since then there have been numerous advances in
both the network architectures and the underlying components. Recently
an accuracy rate of 97.75% was achieved, identifying 1000 classes
in 150,000 images for the ILSVRC2017 challenge. We applied a number
of modern CNN architectures to the problem of classifying sunspots
groups in SDO HMI observations. The input data consisted of SDO HMI
SHARPs magnetograms and the daily McIntosh or Mount Wilson sunspot
classifications provided by the USAF/NOAA. The entire dataset
(2011-2018) was randomly split into three sets, train, test and
validate. The train and test sets were used to optimise the parameters
and hyperparameters of the chosen network architectures to achieve
optimal performance. Once the all the parameters were fixed the accuracy
of the networks were determined using the validation set containing
only unseen data. We present the results of this work together with
some issues encountered and avenues of further research.

---------------------------------------------------------
Title: Three-dimensional magnetic reconnection in a collapsing
coronal loop system
Authors: O'Flannagain, Aidan M.; Maloney, Shane A.; Gallagher, Peter
T.; Browning, Philippa; Refojo, Jose
2018A&A...617A...9O Altcode: 2018arXiv180609365O
Context. Magnetic reconnection is believed to be the primary mechanism
by which non-potential energy stored in coronal magnetic fields is
rapidly released during solar eruptive events. Unfortunately, owing
to the small spatial scales on which reconnection is thought to
occur, it is not directly observable in the solar corona. However,
larger scale processes, such as associated inflow and outflow, and
signatures of accelerated particles have been put forward as evidence
of reconnection. Aims: Using a combination of observations
we explore the origin of a persistent Type I radio source that
accompanies a coronal X-shaped structure during its passage across
the disk. Of particular interest is the time range around a partial
collapse of the structure that is associated with inflow, outflow,
and signatures of particle acceleration. Methods: Imaging radio
observations from the Nançay Radioheliograph were used to localise the
radio source. Solar Dynamics Observatory (SDO) AIA extreme ultraviolet
(EUV) observations from the same time period were analysed, looking for
evidence of inflows and outflows. Further mpole magnetic reconstructions
using SDO HMI observations allowed the magnetic connectivity associated
with the radio source to be determined. Results: The Type I
radio source was well aligned with a magnetic separator identified
in the extrapolations. During the partial collapse, gradual (1 km
s-1) and fast (5 km s-1) inflow phases and fast
(30 km s-1) and rapid (80-100 km s-1) outflow
phases were observed, resulting in an estimated reconnection rate
of ∼0.06. The radio source brightening and dimming was found to be
co-temporal with increased soft X-ray emission observed in both Reuven
Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and Geostationary
Operational Environmental Satellite (GOES). Conclusions:
We interpret the brightening and dimming of the radio emission
as evidence for accelerated electrons in the reconnection region
responding to a gradual fall and rapid rise in electric drift velocity,
in response to the inflowing and outflowing field lines. These results
present a comprehensive example of 3D null-point reconnection. The movies associated to Figs. 2 and 3 are available at <A
href="https://www.aanda.org/10.1051/0004-6361/201732122/olm">https://www.aanda.org/</A>

---------------------------------------------------------
Title: Photospheric Shear Flows in Solar Active Regions and Their
Relation to Flare Occurrence
Authors: Park, Sung-Hong; Guerra, Jordan A.; Gallagher, Peter T.;
Georgoulis, Manolis K.; Bloomfield, D. Shaun
2018SoPh..293..114P Altcode: 2018arXiv180707714P
Solar active regions (ARs) that produce major flares typically exhibit
strong plasma shear flows around photospheric magnetic polarity
inversion lines (MPILs). It is therefore important to quantitatively
measure such photospheric shear flows in ARs for a better understanding
of their relation to flare occurrence. Photospheric flow fields were
determined by applying the Differential Affine Velocity Estimator
for Vector Magnetograms (DAVE4VM) method to a large data set of 2548
coaligned pairs of AR vector magnetograms with 12-min separation over
the period 2012 - 2016. From each AR flow-field map, three shear-flow
parameters were derived corresponding to the mean («S »), maximum
(Smax) and integral (Ssum) shear-flow speeds along
strong-gradient, strong-field MPIL segments. We calculated flaring
rates within 24 h as a function of each shear-flow parameter and we
investigated the relation between the parameters and the waiting
time (τ ) until the next major flare (class M1.0 or above) after
the parameter observation. In general, it is found that the larger
Ssum an AR has, the more likely it is for the AR to produce
flares within 24 h. It is also found that among ARs which produce major
flares, if one has a larger value of Ssum then τ generally
gets shorter. These results suggest that large ARs with widespread
and/or strong shear flows along MPILs tend to not only be more flare
productive, but also produce major flares within 24 h or less.

---------------------------------------------------------
Title: LOFAR4SpaceWeather (LOFAR4SW): Increasing European
Space-Weather Capability with Europe's Largest Radio Telescope
Authors: Bisi, Mario Mark; Vermeulen, René; Fallows, Richard A.;
Vilmer, Nicole; Rothkaehl, Hanna; Verbiest, Joris; Gallagher, Peter
T.; Olberg, Michael; Mevius, Maaijke; Robertson, Stuart C.
2018shin.confE.268B Altcode:
The Low Frequency Array (LOFAR) is one of a relatively-new breed of
radio-astronomy instruments. It covers a wide bandwidth in radio
frequencies (10-250 MHz) with both a high temporal and spatial
resolution using a large number of stations distributed across
Europe. LOFAR consists of a dense core of 24 stations within a 4km
diameter, 14 stations spread further afield across the northeast area
of The Netherlands, and a further 13 stations spread internationally
(six across Germany, three in northern Poland, and one each in France,
Ireland, Sweden, and the UK). Further international sites are under
preparations, which will then expand LOFAR even further across
Europe. LOFAR is one of the world's most-flexible radio instruments
with capabilities that enable studies of several aspects of space
weather to be progressed beyond today's state-of-the-art. However, in
its present setup, it can only be used for space-weather purposes on
a campaign bases. This is where observing time has to be competed for
alongside astronomy and all other types of radio observations requested.

---------------------------------------------------------
Title: Radio observations of energetic electrons in association with
coronal mass ejections in the solar corona
Authors: Carley, Eoin; Vilmer, Nicole; Gallagher, Peter
2018cosp...42E.514C Altcode:
Coronal mass ejections are large eruptions of plasma and magnetic field
from the low solar corona into the heliosphere. These eruptions are
often associated with energetic electrons that produce various kinds
of radio emission. However, there is ongoing investigation into exactly
where, when and how the electron acceleration occurs during flaring and
eruption, and how the radio emission can be exploited as a diagnostic of
the particle acceleration and CME plasma properties. In this talk I will
firstly present recent observations from the Nançay Radioheliograph
(NRH) that show the sites and kinds of electron acceleration that take
place during flaring and eruption, from the destabilisation of a flux
rope to development of a CME. This shows evidence for the tether-cutting
model and numerous sites of electron acceleration both external and
internal to the CME during its development. Secondly, using an analysis
of gyrosynchrotron radiation from NRH and a non-thermal electron
diagnostic using X-ray observations, I show that radio emission can
be produced internal to the CME from non-thermal electrons of energies
&gt;1MeV in a CME core magnetic field strength of 4.4G. Overall, this
reveals how different types of radio observations can be used as a
diagnostic of the locations and kinds of electron acceleration during
an eruptive event, and also how radio may be used to both image CMEs
and give new insight into their dynamics and internal plasma properties.

---------------------------------------------------------
Title: Shock location and CME 3D reconstruction of a solar type II
radio burst with LOFAR
Authors: Zucca, P.; Morosan, D. E.; Rouillard, A. P.; Fallows, R.;
Gallagher, P. T.; Magdalenic, J.; Klein, K. -L.; Mann, G.; Vocks, C.;
Carley, E. P.; Bisi, M. M.; Kontar, E. P.; Rothkaehl, H.; Dabrowski,
B.; Krankowski, A.; Anderson, J.; Asgekar, A.; Bell, M. E.; Bentum,
M. J.; Best, P.; Blaauw, R.; Breitling, F.; Broderick, J. W.; Brouw,
W. N.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; de Geus, E.; Deller,
A.; Duscha, S.; Eislöffel, J.; Garrett, M. A.; Grießmeier, J. M.;
Gunst, A. W.; Heald, G.; Hoeft, M.; Hörandel, J.; Iacobelli, M.;
Juette, E.; Karastergiou, A.; van Leeuwen, J.; McKay-Bukowski, D.;
Mulder, H.; Munk, H.; Nelles, A.; Orru, E.; Paas, H.; Pandey, V. N.;
Pekal, R.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Rowlinson, A.;
Schwarz, D. J.; Shulevski, A.; Sluman, J.; Smirnov, O.; Sobey, C.;
Soida, M.; Thoudam, S.; Toribio, M. C.; Vermeulen, R.; van Weeren,
R. J.; Wucknitz, O.; Zarka, P.
2018A&A...615A..89Z Altcode: 2018arXiv180401025Z
Context. Type II radio bursts are evidence of shocks in the solar
atmosphere and inner heliosphere that emit radio waves ranging from
sub-meter to kilometer lengths. These shocks may be associated with
coronal mass ejections (CMEs) and reach speeds higher than the
local magnetosonic speed. Radio imaging of decameter wavelengths
(20-90 MHz) is now possible with the Low Frequency Array (LOFAR),
opening a new radio window in which to study coronal shocks that
leave the inner solar corona and enter the interplanetary medium and
to understand their association with CMEs. Aims: To this end,
we study a coronal shock associated with a CME and type II radio burst
to determine the locations at which the radio emission is generated,
and we investigate the origin of the band-splitting phenomenon. 
Methods: Thetype II shock source-positions and spectra were obtained
using 91 simultaneous tied-array beams of LOFAR, and the CME was
observed by the Large Angle and Spectrometric Coronagraph (LASCO) on
board the Solar and Heliospheric Observatory (SOHO) and by the COR2A
coronagraph of the SECCHI instruments on board the Solar Terrestrial
Relation Observatory(STEREO). The 3D structure was inferred using
triangulation of the coronographic observations. Coronal magnetic
fields were obtained from a 3D magnetohydrodynamics (MHD) polytropic
model using the photospheric fields measured by the Heliospheric
Imager (HMI) on board the Solar Dynamic Observatory (SDO) as lower
boundary. Results: The type II radio source of the coronal shock
observed between 50 and 70 MHz was found to be located at the expanding
flank of the CME, where the shock geometry is quasi-perpendicular with
θBn 70°. The type II radio burst showed first and second
harmonic emission; the second harmonic source was cospatial with the
first harmonic source to within the observational uncertainty. This
suggests that radio wave propagation does not alter the apparent
location of the harmonic source. The sources of the two split bands
were also found to be cospatial within the observational uncertainty,
in agreement with the interpretation that split bands are simultaneous
radio emission from upstream and downstream of the shock front. The
fast magnetosonic Mach number derived from this interpretation was
found to lie in the range 1.3-1.5. The fast magnetosonic Mach numbers
derived from modelling the CME and the coronal magnetic field around
the type II source were found to lie in the range 1.4-1.6.

---------------------------------------------------------
Title: LOFAR network, new tool for Space Weather Program in the
frame of H2020 action LOFAR4SW
Authors: Rothkaehl, Hanna; Vilmer, Nicole; Fallows, Richard; Gallagher,
Peter; Bisi, Mario M.; Vermeulen, Rene; Verbiest, Joris; Lindqvist,
Michael
2018cosp...42E2892R Altcode:
The LOFAR for Space Weather (LOFAR4SW) is an international project
the aim of which is to deliver the full conceptual and technical
design for creating a new leading-edge European research facility for
space weather science. The project will engage with stakeholders to
prepare a facility which produces unique research data with key impact
on advance predictions of space weather events affecting crucial
technologicalinfrastructures of today's society.The objective of
LOFAR4SW is to prepare for a large scale high-end research facility in
which completely simultaneous, independent observing modes and signal
paths provide continuous access to two research communities: radio
astronomy and space weather research.Space weather science aims, through
observation, monitoring, analysis and modelling, at understanding
and ultimately predicting the complex state of the solar wind -
magnetosphere - ionosphere - thermosphere system, and the potential
impact on biological and technological systems on Earth. Increased
fundamental knowledge, coupled to large-scale monitoring programs,
is needed for much more advanced predictions of the impact of space
weather events on Earth.A fully-implemented LOFAR4SW system will
enable a wide range of solar and space weather research topics to
be tackled and have unique strengths in several high-impact science
areas: tracing the initial launch of a CME; detailed tracking of the
solar wind and CMEs through interplanetary space; in-depth studies of
micro-structure in the Earth's ionosphere. This facility will uniquely
provide the missing link of measurements of the interplanetary magnetic
field on global scales - a key parameter in forecasting the severity
of geomagnetic storm on Earth. The LOFAR4SW will allow scientists to
to answer many important questions with regard to the solar corona,
the heliosphere, and Earth's ionosphere.The action was started on
December 2017 and the aim of this presentation is to show the main
goals of the project and the initiated activities

---------------------------------------------------------
Title: Flare forecasting using the evolution of McIntosh sunspot
classifications
Authors: McCloskey, Aoife E.; Gallagher, Peter T.; Bloomfield, D. Shaun
2018JSWSC...8A..34M Altcode: 2018arXiv180500919M
Most solar flares originate in sunspot groups, where magnetic
field changes lead to energy build-up and release. However, few
flare-forecasting methods use information of sunspot-group evolution,
instead focusing on static point-in-time observations. Here, a new
forecast method is presented based upon the 24-h evolution in McIntosh
classification of sunspot groups. Evolution-dependent ≥C1.0 and
≥M1.0 flaring rates are found from NOAA-numbered sunspot groups over
December 1988-June 1996 (Solar Cycle 22; SC22) before converting to
probabilities assuming Poisson statistics. These flaring probabilities
are used to generate operational forecasts for sunspot groups over July
1996-December 2008 (SC23), with performance studied by verification
metrics. Major findings are: (i) considering Brier skill score (BSS)
for ≥C1.0 flares, the evolution-dependent McIntosh-Poisson method
(BSSevolution = 0.09) performs better than the static
McIntosh-Poisson method (BSSstatic = - 0.09); (ii) low BSS
values arise partly from both methods over-forecasting SC23 flares
from the SC22 rates, symptomatic of ≥C1.0 rates in SC23 being on
average ≈80% of those in SC22 (with ≥M1.0 being ≈50%); (iii)
applying a bias-correction factor to reduce the SC22 rates used in
forecasting SC23 flares yields modest improvement in skill relative
to climatology for both methods (BSSstaticcorr =
0.09 and BSSevolutioncorr = 0.0.20) and improved
forecast reliability diagrams.

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Title: LOFAR observations of the quiet solar corona
Authors: Vocks, C.; Mann, G.; Breitling, F.; Bisi, M. M.; Dąbrowski,
B.; Fallows, R.; Gallagher, P. T.; Krankowski, A.; Magdalenić, J.;
Marqué, C.; Morosan, D.; Rucker, H.
2018A&A...614A..54V Altcode: 2018arXiv180300453V
Context. The quiet solar corona emits meter-wave thermal
bremsstrahlung. Coronal radio emission can only propagate above that
radius, Rω, where the local plasma frequency equals the
observing frequency. The radio interferometer LOw Frequency ARray
(LOFAR) observes in its low band (10-90 MHz) solar radio emission
originating from the middle and upper corona. Aims: We present
the first solar aperture synthesis imaging observations in the low band
of LOFAR in 12 frequencies each separated by 5 MHz. From each of these
radio maps we infer Rω, and a scale height temperature,
T. These results can be combined into coronal density and temperature
profiles. Methods: We derived radial intensity profiles
from the radio images. We focus on polar directions with simpler,
radial magnetic field structure. Intensity profiles were modeled by
ray-tracing simulations, following wave paths through the refractive
solar corona, and including free-free emission and absorption. We
fitted model profiles to observations with Rω and T as
fitting parameters. Results: In the low corona, Rω
&lt; 1.5 solar radii, we find high scale height temperatures up to
2.2 × 106 K, much more than the brightness temperatures
usually found there. But if all Rω values are combined into
a density profile, this profile can be fitted by a hydrostatic model
with the same temperature, thereby confirming this with two independent
methods. The density profile deviates from the hydrostatic model above
1.5 solar radii, indicating the transition into the solar wind. 
Conclusions: These results demonstrate what information can be gleaned
from solar low-frequency radio images. The scale height temperatures
we find are not only higher than brightness temperatures, but also
than temperatures derived from coronograph or extreme ultraviolet
(EUV) data. Future observations will provide continuous frequency
coverage. This continuous coverage eliminates the need for local
hydrostatic density models in the data analysis and enables the
analysis of more complex coronal structures such as those with closed
magnetic fields.

---------------------------------------------------------
Title: Eclipse Science from 50,000 Feet: New Coronal Results from
NASA WB-57F High-Altitude Aircraft Observations of the 2017 Total
Solar Eclipse
Authors: Caspi, Amir; Tsang, Constantine; Seaton, Daniel B.; DeForest,
Craig; Bryans, Paul; DeLuca, Edward; Tomczyk, Steven; Burkepile,
Joan; Casey, Thomas Anthony; Collier, John; Darrow, Donald DD; Del
Rosso, Dominic; Durda, Daniel D.; Gallagher, Peter; Gascar, Jasmine;
Golub, Leon; Jacyna, Matthew; Johnson, David DJ; Judge, Philip G.;
Klemm, Cary; Laurent, Glenn Thomas; Lewis, Johanna; Mallini, Charles;
Parent, Thomas Duster; Propp, Timothy; Steffl, Andrew; Warner, Jeff;
West, Matthew John; Wiseman, John; Yates, Mallory; Zhukov, Andrei
2018tess.conf31302C Altcode:
Total solar eclipses present rare opportunities to study the complex
solar corona, down to altitudes of just a few percent of a solar
radius above the surface. Studying the corona is critical to gaining
a better understanding of the dominant driver of space weather that
affects human assets on Earth and elsewhere. For example, it is still
poorly understood how the corona is heated to temperatures of 1-2 MK
globally and up to 5-10 MK above active regions, while the underlying
chromosphere is 100 times cooler. The stability of large-scale coronal
structures and the extent of their reach to the middle and outer corona
are also not well known, limited in large part by sensitivities and
fields of view of existing observations. Airborne observations
during a total eclipse provide unique advantages. By flying in the
stratosphere at altitudes of 50 kft or higher, they avoid all weather,
the seeing quality is enormously improved, and additional wavelengths
such as near-IR also become available due to significantly reduced
water absorption. An airborne observatory can also follow the Moon's
shadow, increasing the total observing time by 50% or more. We
present current results of solar coronal measurements from airborne
observations of the 2017 Great American Total Solar Eclipse using two
of NASA's WB-57 high-altitude research aircraft, each equipped with
two 8.7-inch telescopes feeding high-sensitivity visible (green line
and nearby continuum) and medium-wave IR (3-5 μm) cameras operating
at high cadence (30 Hz) with ∼3 arcsec/pixel platescale and ±3
Rsun fields of view. The two aircraft flew along the eclipse
path, separated by ∼110 km, to observe a total of ∼7.5 minutes
of totality in both visible and MWIR. These observations enable
groundbreaking studies of high-speed coherent motion - including
possible Alfvén waves and nanojets - in the lower and middle corona
that could shed light on coronal heating processes and the formation
and stability of coronal structures. Our MWIR observations of a cool
prominence and hot coronal active region plasma will be combined with
spectra from the AIR-Spec instrument, flown concurrently on NCAR's
HIAPER GV. We review the WB-57 eclipse mission and the current results
of analysis on the visible and IR coronal measurements, along with an
outlook for future analysis and missions.

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Title: CMEs in the Heliosphere: I. A Statistical Analysis of the
Observational Properties of CMEs Detected in the Heliosphere from
2007 to 2017 by STEREO/HI-1
Authors: Harrison, R. A.; Davies, J. A.; Barnes, D.; Byrne, J. P.;
Perry, C. H.; Bothmer, V.; Eastwood, J. P.; Gallagher, P. T.; Kilpua,
E. K. J.; Möstl, C.; Rodriguez, L.; Rouillard, A. P.; Odstrčil, D.
2018SoPh..293...77H Altcode: 2018arXiv180402320H
We present a statistical analysis of coronal mass ejections (CMEs)
imaged by the Heliospheric Imager (HI) instruments on board NASA's
twin-spacecraft STEREO mission between April 2007 and August 2017 for
STEREO-A and between April 2007 and September 2014 for STEREO-B. The
analysis exploits a catalogue that was generated within the FP7
HELCATS project. Here, we focus on the observational characteristics
of CMEs imaged in the heliosphere by the inner (HI-1) cameras, while
following papers will present analyses of CME propagation through
the entire HI fields of view. More specifically, in this paper we
present distributions of the basic observational parameters - namely
occurrence frequency, central position angle (PA) and PA span - derived
from nearly 2000 detections of CMEs in the heliosphere by HI-1 on
STEREO-A or STEREO-B from the minimum between Solar Cycles 23 and 24
to the maximum of Cycle 24; STEREO-A analysis includes a further 158
CME detections from the descending phase of Cycle 24, by which time
communication with STEREO-B had been lost. We compare heliospheric CME
characteristics with properties of CMEs observed at coronal altitudes,
and with sunspot number. As expected, heliospheric CME rates correlate
with sunspot number, and are not inconsistent with coronal rates
once instrumental factors/differences in cataloguing philosophy are
considered. As well as being more abundant, heliospheric CMEs, like
their coronal counterparts, tend to be wider during solar maximum. Our
results confirm previous coronagraph analyses suggesting that CME launch
sites do not simply migrate to higher latitudes with increasing solar
activity. At solar minimum, CMEs tend to be launched from equatorial
latitudes, while at maximum, CMEs appear to be launched over a much
wider latitude range; this has implications for understanding the
CME/solar source association. Our analysis provides some supporting
evidence for the systematic dragging of CMEs to lower latitude as they
propagate outwards.

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Title: LOFAR for Space Weather (LOFAR4SW) H2020 program
Authors: Rothkaehl, Hanna; Vermeulen, René; Fallows, Richard;
Verbiest, Joris; Vilmer, Nicole; Olberg, Michael; Bisi, Mario;
Gallagher, Peter
2018EGUGA..2018974R Altcode:
The LOFAR for Space Weather (LOFAR4SW) is an international project the
aim of which is to deliver the full conceptual and technical design
for creating a new leading-edge European research facility for space
weather science. The project will engage with stakeholders to prepare a
facility which produces unique research data with key impact on advance
predictions of space weather events affecting crucial technological
infrastructures of today's society. The objective of LOFAR4SW is
to prepare for a large scale high-end research facility in which
completely simultaneous, independent observing modes and signal paths
provide continuous access to two research communities: radio astronomy
and space weather research. Space weather science aims, through
observation, monitoring, analysis and modelling, at understanding
and ultimately predicting the complex state of the solar wind -
magnetosphere - ionosphere - thermosphere system, and the potential
impact on biological and technological systems on Earth. Increased
fundamental knowledge, coupled to large-scale monitoring programs,
is needed for much more advanced predictions of the impact of space
weather events on Earth. A fully-implemented LOFAR4SW system will
enable a wide range of solar and space weather research topics to
be tackled and have unique strengths in several high-impact science
areas: tracing the initial launch of a CME; detailed tracking of the
solar wind and CMEs through interplanetary space; in-depth studies of
micro-structure in the Earth's ionosphere. This facility will uniquely
provide the missing link of measurements of the interplanetary magnetic
field on global scales - a key parameter in forecasting the severity
of geomagnetic storm on Earth. The LOFAR4SW will allow scientists to
to answer many important questions with regard to the solar corona,
the heliosphere, and Earth's ionosphere. The action was started on
December 2017 and the aim of this presentation is to show the main
goals of the project and the initiated activities

---------------------------------------------------------
Title: VizieR Online Data Catalog: Quasi-periodic pulsations in
solar flares (Inglis+, 2016)
Authors: Inglis, A. R.; Ireland, J.; Dennis, B. R.; Hayes, L.;
Gallagher, P.
2018yCat..18330284I Altcode:
We have used data from the Geostationary Operational Environmental
Satellite (GOES) instrument series, and from Fermi/Gamma-ray Burst
Monitor (GBM). For this reason, we choose the interval 2011 February 1
- 2015 December 31, as it not only coincides with the availability of
GOES-15 satellite data, but also includes regular solar observations
by GBM. GOES satellites are equipped with solar X-ray detectors
that record the incident flux in the 0.5-4Å and 1-8Å wavelength
ranges. Solar X-ray data from the most recent satellite, GOES-15,
has been available since 2010 at a nominal 2s cadence. To access the
GOES catalog, we use the Heliophysics Event Knowledgebase (HEK). Fermi/GBM operates in the 8keV-40MeV range and regularly observes
emission from solar flares, with a solar duty cycle of ~60%, similar
to the solar-dedicated Reuven Ramaty High Energy Solar Spectroscopic
Imager (RHESSI). To accumulate the database of Fermi/GBM events,
we use the GBM trigger catalog produced by the instrument team,
selecting all events marked as flares. (2 data files).

---------------------------------------------------------
Title: Connecting Coronal Mass Ejections to Their Solar Active Region
Sources: Combining Results from the HELCATS and FLARECAST Projects
Authors: Murray, Sophie A.; Guerra, Jordan A.; Zucca, Pietro; Park,
Sung-Hong; Carley, Eoin P.; Gallagher, Peter T.; Vilmer, Nicole;
Bothmer, Volker
2018SoPh..293...60M Altcode: 2018arXiv180306529M
Coronal mass ejections (CMEs) and other solar eruptive phenomena can be
physically linked by combining data from a multitude of ground-based
and space-based instruments alongside models; however, this can be
challenging for automated operational systems. The EU Framework Package
7 HELCATS project provides catalogues of CME observations and properties
from the Heliospheric Imagers on board the two NASA/STEREO spacecraft
in order to track the evolution of CMEs in the inner heliosphere. From
the main HICAT catalogue of over 2,000 CME detections, an automated
algorithm has been developed to connect the CMEs observed by STEREO
to any corresponding solar flares and active-region (AR) sources
on the solar surface. CME kinematic properties, such as speed and
angular width, are compared with AR magnetic field properties, such as
magnetic flux, area, and neutral line characteristics. The resulting
LOWCAT catalogue is also compared to the extensive AR property
database created by the EU Horizon 2020 FLARECAST project, which
provides more complex magnetic field parameters derived from vector
magnetograms. Initial statistical analysis has been undertaken on the
new data to provide insight into the link between flare and CME events,
and characteristics of eruptive ARs. Warning thresholds determined
from analysis of the evolution of these parameters is shown to be a
useful output for operational space weather purposes. Parameters of
particular interest for further analysis include total unsigned flux,
vertical current, and current helicity. The automated method developed
to create the LOWCAT catalogue may also be useful for future efforts
to develop operational CME forecasting.

---------------------------------------------------------
Title: Tracking of an electron beam through the solar corona with
LOFAR
Authors: Mann, G.; Breitling, F.; Vocks, C.; Aurass, H.; Steinmetz,
M.; Strassmeier, K. G.; Bisi, M. M.; Fallows, R. A.; Gallagher, P.;
Kerdraon, A.; Mackinnon, A.; Magdalenic, J.; Rucker, H.; Anderson,
J.; Asgekar, A.; Avruch, I. M.; Bell, M. E.; Bentum, M. J.; Bernardi,
G.; Best, P.; Bîrzan, L.; Bonafede, A.; Broderick, J. W.; Brüggen,
M.; Butcher, H. R.; Ciardi, B.; Corstanje, A.; de Gasperin, F.;
de Geus, E.; Deller, A.; Duscha, S.; Eislöffel, J.; Engels, D.;
Falcke, H.; Fender, R.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.;
Grießmeier, J.; Gunst, A. W.; van Haarlem, M.; Hassall, T. E.;
Heald, G.; Hessels, J. W. T.; Hoeft, M.; Hörandel, J.; Horneffer,
A.; Juette, E.; Karastergiou, A.; Klijn, W. F. A.; Kondratiev, V. I.;
Kramer, M.; Kuniyoshi, M.; Kuper, G.; Maat, P.; Markoff, S.; McFadden,
R.; McKay-Bukowski, D.; McKean, J. P.; Mulcahy, D. D.; Munk, H.;
Nelles, A.; Norden, M. J.; Orru, E.; Paas, H.; Pandey-Pommier, M.;
Pandey, V. N.; Pizzo, R.; Polatidis, A. G.; Rafferty, D.; Reich,
W.; Röttgering, H.; Scaife, A. M. M.; Schwarz, D. J.; Serylak,
M.; Sluman, J.; Smirnov, O.; Stappers, B. W.; Tagger, M.; Tang, Y.;
Tasse, C.; ter Veen, S.; Thoudam, S.; Toribio, M. C.; Vermeulen, R.;
van Weeren, R. J.; Wise, M. W.; Wucknitz, O.; Yatawatta, S.; Zarka,
P.; Zensus, J. A.
2018A&A...611A..57M Altcode:
The Sun's activity leads to bursts of radio emission, among other
phenomena. An example is type-III radio bursts. They occur frequently
and appear as short-lived structures rapidly drifting from high to low
frequencies in dynamic radio spectra. They are usually interpreted as
signatures of beams of energetic electrons propagating along coronal
magnetic field lines. Here we present novel interferometric LOFAR (LOw
Frequency ARray) observations of three solar type-III radio bursts
and their reverse bursts with high spectral, spatial, and temporal
resolution. They are consistent with a propagation of the radio sources
along the coronal magnetic field lines with nonuniform speed. Hence,
the type-III radio bursts cannot be generated by a monoenergetic
electron beam, but by an ensemble of energetic electrons with a spread
distribution in velocity and energy. Additionally, the density profile
along the propagation path is derived in the corona. It agrees well
with three-fold coronal density model by (1961, ApJ, 133, 983).

---------------------------------------------------------
Title: Active Region Photospheric Magnetic Properties Derived from
Line-of-Sight and Radial Fields
Authors: Guerra, J. A.; Park, S. -H.; Gallagher, P. T.; Kontogiannis,
I.; Georgoulis, M. K.; Bloomfield, D. S.
2018SoPh..293....9G Altcode: 2017arXiv171206902G
The effect of using two representations of the normal-to-surface
magnetic field to calculate photospheric measures that are related
to the active region (AR) potential for flaring is presented. Several
AR properties were computed using line-of-sight (Blos) and
spherical-radial (Br) magnetograms from the Space-weather HMI
Active Region Patch (SHARP) products of the Solar Dynamics Observatory,
characterizing the presence and features of magnetic polarity inversion
lines, fractality, and magnetic connectivity of the AR photospheric
field. The data analyzed correspond to ≈4 ,000 AR observations,
achieved by randomly selecting 25% of days between September 2012 and
May 2016 for analysis at 6-hr cadence. Results from this statistical
study include: i) the Br component results in a slight
upwards shift of property values in a manner consistent with a
field-strength underestimation by the Blos component;
ii) using the Br component results in significantly lower
inter-property correlation in one-third of the cases, implying more
independent information as regards the state of the AR photospheric
magnetic field; iii) flaring rates for each property vary between
the field components in a manner consistent with the differences
in property-value ranges resulting from the components; iv) flaring
rates generally increase for higher values of properties, except the
Fourier spectral power index that has flare rates peaking around a
value of 5 /3 . These findings indicate that there may be advantages
in using Br rather than Blos in calculating
flare-related AR magnetic properties, especially for regions located
far from central meridian.

---------------------------------------------------------
Title: Automated coronal hole identification via multi-thermal
intensity segmentation
Authors: Garton, Tadhg M.; Gallagher, Peter T.; Murray, Sophie A.
2018JSWSC...8A...2G Altcode: 2017arXiv171111476G; 2018JSWSC...8A..02G
Coronal holes (CH) are regions of open magnetic fields that
appear as dark areas in the solar corona due to their low density
and temperature compared to the surrounding quiet corona. To
date, accurate identification and segmentation of CHs has been a
difficult task due to their comparable intensity to local quiet Sun
regions. Current segmentation methods typically rely on the use of
single Extreme Ultra-Violet passband and magnetogram images to extract
CH information. Here, the coronal hole identification via multi-thermal
emission recognition algorithm (CHIMERA) is described, which analyses
multi-thermal images from the atmospheric image assembly (AIA) onboard
the solar dynamics observatory (SDO) to segment coronal hole boundaries
by their intensity ratio across three passbands (171 Å, 193 Å, and
211 Å). The algorithm allows accurate extraction of CH boundaries
and many of their properties, such as area, position, latitudinal and
longitudinal width, and magnetic polarity of segmented CHs. From these
properties, a clear linear relationship was identified between the
duration of geomagnetic storms and coronal hole areas. CHIMERA can
therefore form the basis of more accurate forecasting of the start
and duration of geomagnetic storms.

---------------------------------------------------------
Title: Chasing the Great American 2017 Total Solar Eclipse: Coronal
Results from NASA's WB-57F High-Altitude Research Aircraft
Authors: Caspi, A.; Tsang, C.; DeForest, C. E.; Seaton, D. B.; Bryans,
P.; Burkepile, J.; Casey, T. A.; Collier, J.; Darrow, D.; DeLuca,
E.; Durda, D. D.; Gallagher, P.; Golub, L.; Judge, P. G.; Laurent,
G. T.; Lewis, J.; Mallini, C.; Parent, T.; Propp, T.; Steffl, A.;
Tomczyk, S.; Warner, J.; West, M. J.; Wiseman, J.; Zhukov, A.
2017AGUFMSH24A..05C Altcode:
Total solar eclipses present rare opportunities to study the complex
solar corona, down to altitudes of just a few percent of a solar
radius above the surface, using ground-based and airborne observatories
that would otherwise be dominated by the intense solar disk and high
sky brightness. Studying the corona is critical to gaining a better
understanding of physical processes that occur on other stars and
astrophysical objects, as well as understanding the dominant driver of
space weather that affects human assets at Earth and elsewhere. For
example, it is still poorly understood how the corona is heated to
temperatures of 1-2 MK globally and up to 5-10 MK above active regions,
while the underlying chromosphere is 100 times cooler; numerous theories
abound, but are difficult to constrain due to the limited sensitivities
and cadences of prior measurements. The origins and stability of coronal
fans, and the extent of their reach to the middle and outer corona,
are also not well known, limited in large part by sensitivities and
fields of view of existing observations. Airborne observations during
the eclipse provide unique advantages; by flying in the stratosphere
at altitudes of 50 kft or higher, they avoid all weather, the seeing
quality is enormously improved, and additional wavelengths such as
near- IR also become available due to significantly reduced water
absorption. For an eclipse, an airborne observatory can also follow the
shadow, increasing the total observing time by 50% or more. We present
results of solar coronal measurements from airborne observations of
the 2017 Great American Total Solar Eclipse using two of NASA's WB-57
high-altitude research aircraft, each equipped with two 8.7" telescopes
feeding high-sensitivity visible (green-line) and medium-wave IR (3-5
μm) cameras operating at high cadence (30 Hz) with 3 arcsec/pixel
platescale and ±3 R_sun fields of view. The aircraft flew along the
eclipse path, separated by 110 km, to observe a summed 7.5 minutes of
totality in both visible and NIR, enabling groundbreaking studies of
high-speed wave motions and nanojets in the lower corona, the structure
and extent of coronal fans, and constraints on a potential primordial
dust ring around the Sun. We review the mission, and the results of
analysis on the visible and IR coronal measurements.

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Title: Quasi-Periodic Pulsations in the Earth's Ionosphere
Synchronized with Solar Flare Emission
Authors: Hayes, L.; Gallagher, P.; McCauley, J.; Dennis, B. R.;
Ireland, J.; Inglis, A. R.
2017AGUFMSH51C2514H Altcode:
Solar flare activity is a powerful factor affecting the geophysical
processes in the Earth's ionosphere. In particular, X-ray photons with
wavelength &lt; 10 A can penetrate down to the D-region ( 60-90 km in
altitude) resulting in a dramatic increase of ionization in this lowest
lying region of the Earth's ionosphere. This manifests as a substantial
enhancement of electron density height profile at these altitudes to
extents large enough to change the propagation conditions for Very
Low Frequency (VLF 3-30 kHz) radio waves that travel in the waveguide
formed by the Earth and the lower ionosphere. Recently, it has become
clear that flares exhibit quasi-periodic pulsations with periods of
seconds to minutes at EUV, X-ray and gamma-ray wavelengths. To date,
it has not been known if the Earth's ionosphere is sensitive to these
dynamic solar pulsations. Here, we report ionospheric pulsations with
periods of 20 minutes that are synchronized with a set of pulsating
flare loops using VLF observations of the ionospheric D-layer together
with X-ray and EUV observations of a solar flare from the NOAA/GOES
and NASA/SDO satellites. Modeling of the ionosphere show that the
D-region electron density varies by up to an order of magnitude over
the timescale of the pulsations. Our results show that the Earth's
ionosphere is more sensitive to small-scale changes in solar activity
than previously thought.

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Title: The Next Level in Automated Solar Flare Forecasting: the EU
FLARECAST Project
Authors: Georgoulis, M. K.; Bloomfield, D.; Piana, M.; Massone,
A. M.; Gallagher, P.; Vilmer, N.; Pariat, E.; Buchlin, E.; Baudin,
F.; Csillaghy, A.; Soldati, M.; Sathiapal, H.; Jackson, D.; Alingery,
P.; Argoudelis, V.; Benvenuto, F.; Campi, C.; Florios, K.; Gontikakis,
C.; Guennou, C.; Guerra, J. A.; Kontogiannis, I.; Latorre, V.; Murray,
S.; Park, S. H.; Perasso, A.; Sciacchitano, F.; von Stachelski, S.;
Torbica, A.; Vischi, D.
2017AGUFMSA21C..07G Altcode:
We attempt an informative description of the Flare Likelihood And
Region Eruption Forecasting (FLARECAST) project, European Commission's
first large-scale investment to explore the limits of reliability
and accuracy achieved for the forecasting of major solar flares. We
outline the consortium, top-level objectives and first results of
the project, highlighting the diversity and fusion of expertise
needed to deliver what was promised. The project's final product,
featuring an openly accessible, fully modular and free to download
flare forecasting facility will be delivered in early 2018. The
project's three objectives, namely, science, research-to-operations and
dissemination / communication, are also discussed: in terms of science,
we encapsulate our close-to-final assessment on how close (or far)
are we from a practically exploitable solar flare forecasting. In
terms of R2O, we briefly describe the architecture of the FLARECAST
infrastructure that includes rigorous validation for each forecasting
step. From the three different communication levers of the project we
finally focus on lessons learned from the two-way interaction with the
community of stakeholders and governmental organizations. The FLARECAST
project has received funding from the European Union's Horizon 2020
research and innovation programme under grant agreement No. 640216.

---------------------------------------------------------
Title: The Heliospheric Cataloguing, Analysis and Techniques Service
(HELCATS) project
Authors: Barnes, D.; Harrison, R. A.; Davies, J. A.; Perry, C. H.;
Moestl, C.; Rouillard, A.; Bothmer, V.; Rodriguez, L.; Eastwood,
J. P.; Kilpua, E.; Gallagher, P.; Odstrcil, D.
2017AGUFMSH31A2713B Altcode:
Understanding solar wind evolution is fundamental to advancing our
knowledge of energy and mass transport in the solar system, whilst
also being crucial to space weather and its prediction. The advent of
truly wide-angle heliospheric imaging has revolutionised the study of
solar wind evolution, by enabling direct and continuous observation
of both transient and background components of the solar wind as they
propagate from the Sun to 1 AU and beyond. The recently completed,
EU-funded FP7 Heliospheric Cataloguing, Analysis and Techniques
Service (HELCATS) project (1st May 2014 - 30th April 2017) combined
European expertise in heliospheric imaging, built up over the last
decade in particular through leadership of the Heliospheric Imager
(HI) instruments aboard NASA's STEREO mission, with expertise in
solar and coronal imaging as well as the interpretation of in-situ
and radio diagnostic measurements of solar wind phenomena. HELCATS
involved: (1) the cataloguing of transient (coronal mass ejections)
and background (stream/corotating interaction regions) solar wind
structures observed by the STEREO/HI instruments, including estimates of
their kinematic properties based on a variety of modelling techniques;
(2) the verification of these kinematic properties through comparison
with solar source observations and in-situ measurements at multiple
points throughout the heliosphere; (3) the assessment of the potential
for initialising numerical models based on the derived kinematic
properties of transient and background solar wind components; and (4)
the assessment of the complementarity of radio observations (Type II
radio bursts and interplanetary scintillation) in the detection and
analysis of heliospheric structure in combination with heliospheric
imaging observations. In this presentation, we provide an overview
of the HELCATS project emphasising, in particular, the principal
achievements and legacy of this unprecedented project.

---------------------------------------------------------
Title: Pulsations in the Earth's Lower Ionosphere Synchronized With
Solar Flare Emission
Authors: Hayes, Laura A.; Gallagher, Peter T.; McCauley, Joseph;
Dennis, Brian R.; Ireland, Jack; Inglis, Andrew
2017JGRA..122.9841H Altcode: 2017arXiv171001725H
Solar flare emission at X-ray and extreme ultraviolet (EUV) energies
can cause substantial enhancements in the electron density in the
Earth's lower ionosphere. It has now become clear that flares exhibit
quasi-periodic pulsations with timescales of minutes at X-ray energies,
but to date, it has not been known if the ionosphere is sensitive to
this variability. Here using a combination of very low frequency (24
kHz) measurement together with space-based X-ray and EUV observations,
we report pulsations of the ionospheric D region, which are synchronized
with a set of pulsating flare loops. Modeling of the ionosphere show
that the D region electron density varies by up to an order of magnitude
over the timescale of the pulsations (∼ 20 min). Our results reveal
that the Earth's ionosphere is more sensitive to small-scale changes
in solar soft X-ray flux than previously thought and implies that
planetary ionospheres are closely coupled to small-scale changes in
solar/stellar activity.

---------------------------------------------------------
Title: The association of a J-burst with a solar jet
Authors: Morosan, D. E.; Gallagher, P. T.; Fallows, R. A.; Reid, H.;
Mann, G.; Bisi, M. M.; Magdalenić, J.; Rucker, H. O.; Thidé, B.;
Vocks, C.; Anderson, J.; Asgekar, A.; Avruch, I. M.; Bell, M. E.;
Bentum, M. J.; Best, P.; Blaauw, R.; Bonafede, A.; Breitling, F.;
Broderick, J. W.; Brüggen, M.; Cerrigone, L.; Ciardi, B.; de Geus, E.;
Duscha, S.; Eislöffel, J.; Falcke, H.; Garrett, M. A.; Grießmeier,
J. M.; Gunst, A. W.; Hoeft, M.; Iacobelli, M.; Juette, E.; Kuper,
G.; McFadden, R.; McKay-Bukowski, D.; McKean, J. P.; Mulcahy, D. D.;
Munk, H.; Nelles, A.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pandey,
V. N.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Schwarz, D. J.; Sluman,
J.; Smirnov, O.; Steinmetz, M.; Tagger, M.; ter Veen, S.; Thoudam,
S.; Toribio, M. C.; Vermeulen, R.; van Weeren, R. J.; Wucknitz, O.;
Zarka, P.
2017A&A...606A..81M Altcode: 2017arXiv170703428M
Context. The Sun is an active star that produces large-scale energetic
events such as solar flares and coronal mass ejections, and numerous
smaller scale events such as solar jets. These events are often
associated with accelerated particles that can cause emission at radio
wavelengths. The reconfiguration of the solar magnetic field in the
corona is believed to be the cause of the majority of solar energetic
events and accelerated particles. Aims: Here, we investigate a
bright J-burst that was associated with a solar jet and the possible
emission mechanism causing these two phenomena. Methods: We used
data from the Solar Dynamics Observatory (SDO) to observe a solar jet
and radio data from the Low Frequency Array (LOFAR) and the Nançay
Radioheliograph (NRH) to observe a J-burst over a broad frequency range
(33-173 MHz) on 9 July 2013 at 11:06 UT. Results: The J-burst
showed fundamental and harmonic components and was associated with a
solar jet observed at extreme ultraviolet wavelengths with SDO. The
solar jet occurred in the northern hemisphere at a time and location
coincident with the radio burst and not inside a group of complex
active regions in the southern hemisphere. The jet occurred in the
negative polarity region of an area of bipolar plage. Newly emerged
positive flux in this region appeared to be the trigger of the jet. Conclusions: Magnetic reconnection between the overlying coronal
field lines and the newly emerged positive field lines is most likely
the cause of the solar jet. Radio imaging provides a clear association
between the jet and the J-burst, which shows the path of the accelerated
electrons. These electrons travelled from a region in the vicinity
of the solar jet along closed magnetic field lines up to the top of a
closed magnetic loop at a height of 360 Mm. Such small-scale complex
eruptive events arising from magnetic reconnection could facilitate
accelerated electrons to produce continuously the large numbers of Type
III bursts observed at low frequencies, in a similar way to the J-burst
analysed here. The movie attached to Fig. 4 is available at <A
href="http://www.aanda.org/10.1051/0004-6361/201629996/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: Searching for evidence of quasi-periodic pulsations in solar
flares using the AFINO code
Authors: Inglis, Andrew; Ireland, Jack; Dennis, Brian R.; Hayes,
Laura Ann; Gallagher, Peter T.
2017SPD....4840005I Altcode:
The AFINO (Automated Flare Inference of Oscillations) code is a new
tool to allow analysis of temporal solar data in search of oscillatory
signatures. Using AFINO, we carry out a large-scale search for evidence
of signals consistent with quasi-periodic pulsations (QPP) in solar
flares, focusing on the 1-300 s timescale. We analyze 675 M- and X-class
flares observed by GOES in 1-8 Å soft X-rays between 2011 February
1 and 2015 December 31. Additionally, over the same era we analyze
Fermi/GBM 15-25 keV X-ray data for each of these flares associated
with a GBM solar flare trigger, a total of 261 events. Using a model
comparison method and the Bayesian Information Criterion statistic,
we determine whether there is evidence for a substantial enhancement
in the Fourier power spectrum that may be consistent with a QPP-like
signature.Quasi-steady periodic signatures appear more prevalently in
thermal soft X-ray data than in the counterpart hard X-ray emission:
according to AFINO ~30% of GOES flares but only ~8% of the same
flares observed by GBM show strong signatures consistent with
classical interpretations of QPP, which include MHD wave processes
and oscillatory reconnection events. For both datasets, preferred
characteristic timescales of ~5-30 s were found in the QPP-like events,
with no clear dependence on flare magnitude. Individual events in the
sample also show similar characteristic timescales in both GBM and GOES
data sets, indicating that the same phenomenon is sometimes observed
simultaneously in soft and hard X-rays. We discuss the implications
of these survey results, and future developments of the analysis
method. AFINO continues to run daily on new flares observed by GOES,
and the full AFINO catalogue is made available online.

---------------------------------------------------------
Title: First results from the NASA WB-57 airborne observations of
the Great American 2017 Total Solar Eclipse
Authors: Caspi, Amir; Tsang, Constantine; DeForest, Craig; Seaton,
Daniel B.; Bryans, Paul; Tomczyk, Steven; Burkepile, Joan; Judge,
Phil; DeLuca, Edward E.; Golub, Leon; Gallagher, Peter T.; Zhukov,
Andrei; West, Matthew; Durda, Daniel D.; Steffl, Andrew J.
2017SPD....4810701C Altcode:
Total solar eclipses present rare opportunities to study the complex
solar corona, down to altitudes of just a few percent of a solar
radius above the surface, using ground-based and airborne observatories
that would otherwise be dominated by the intense solar disk and high
sky brightness. Studying the corona is critical to gaining a better
understanding of physical processes that occur on other stars and
astrophysical objects, as well as understanding the dominant driver of
space weather that affects human assets at Earth and elsewhere. For
example, it is still poorly understood how the corona is heated to
temperatures of 1-2 MK globally and up to 5-10 MK above active regions,
while the underlying chromosphere is 100 times cooler; numerous theories
abound, but are difficult to constrain due to the limited sensitivities
and cadences of prior measurements. The origins and stability of coronal
fans, and the extent of their reach to the middle and outer corona,
are also not well known, limited in large part by sensitivities and
fields of view of existing observations.Airborne observations during
the eclipse provide unique advantages; by flying in the stratosphere
at altitudes of 50 kft or higher, they avoid all weather, the seeing
quality is enormously improved, and additional wavelengths such
as near-IR also become available due to significantly reduced water
absorption. For an eclipse, an airborne observatory can also follow the
shadow, increasing the total observing time by 50% or more.We present
the first results from airborne observations of the 2017 Great American
Total Solar Eclipse using two of NASA's WB-57 research aircraft, each
equipped with two 8.7" telescopes feeding high-sensitivity visible
(green-line) and near-IR (3-5 µm) cameras operating at high cadence
(30 Hz) with ~3 arcsec/pixel platescale and ±3 R_sun fields of
view. The aircraft will fly along the eclipse path, separated by ~90
km, to observe a summed ~8 minutes of totality in both visible and
NIR, enabling groundbreaking studies of high-speed wave motions and
nanojets in the lower corona, the structure and extent of coronal fans,
and constraints on a potential primordial dust ring around the Sun.

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Title: Kinematics and shock locations of a spatial resolved solar
type II radio burst with LOFAR
Authors: Zucca, Pietro; Morosan, Diana; Gallagher, Peter T.; Fallows,
Richard; Rouillard, Alexis; Magdalenic, Jasmina; Vocks, Christian;
Marqué, Christophe; Klein, Karl-Ludwig; Mann, Gottfried
2017shin.confE..14Z Altcode:
Type II radio bursts are evidence of shocks in the solar atmosphere
emitting radio waves ranging from metric to kilometric lengths. These
shocks may be associated with coronal mass ejections (CMEs) reaching
super-Alfvénic speeds. Radio imaging of the decameter wavelengths is
now possible with the Low Frequency Array (LOFAR), opening a new radio
window to study coronal radio shocks leaving the inner solar corona and
entering the interplanetary medium and understand their association with
CMEs. Here, we study a coronal shock associated with a CME and type
II radio burst to determine the location where the shock is triggered
in relation to the propagating CME, the ambient medium Alfvén speed and
the orientation of the coronal magnetic field. The type II shock imaging
and spectra were obtained using 91 simultaneous tied-array beams of
LOFAR while the CME was observed by the Large Angle and Spectrometric
Coronagraph (LASCO) on board the Solar and Heliospheric Observatory
(SOHO). Using the tied array beam observing mode of LOFAR we
were able to locate the type II radio shock position between 45 and
75 MHz and relate it to the expanding flank of a CME leaving the inner
corona. The radio emission associated with the type II shock was found
to be located at the flank of the CME in a region where the mach number
is between 1.5 to 2.0 and the shock geometry is quasi-perpendicular.

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Title: Modeling observations of solar coronal mass ejections with
heliospheric imagers verified with the Heliophysics System Observatory
Authors: Möstl, C.; Isavnin, A.; Boakes, P. D.; Kilpua, E. K. J.;
Davies, J. A.; Harrison, R. A.; Barnes, D.; Krupar, V.; Eastwood,
J. P.; Good, S. W.; Forsyth, R. J.; Bothmer, V.; Reiss, M. A.;
Amerstorfer, T.; Winslow, R. M.; Anderson, B. J.; Philpott, L. C.;
Rodriguez, L.; Rouillard, A. P.; Gallagher, P.; Nieves-Chinchilla,
T.; Zhang, T. L.
2017SpWea..15..955M Altcode: 2017arXiv170300705M
We present an advance toward accurately predicting the arrivals of
coronal mass ejections (CMEs) at the terrestrial planets, including
Earth. For the first time, we are able to assess a CME prediction model
using data over two thirds of a solar cycle of observations with the
Heliophysics System Observatory. We validate modeling results of 1337
CMEs observed with the Solar Terrestrial Relations Observatory (STEREO)
heliospheric imagers (HI) (science data) from 8 years of observations
by five in situ observing spacecraft. We use the self-similar expansion
model for CME fronts assuming 60° longitudinal width, constant speed,
and constant propagation direction. With these assumptions we find that
23%-35% of all CMEs that were predicted to hit a certain spacecraft
lead to clear in situ signatures, so that for one correct prediction,
two to three false alarms would have been issued. In addition, we find
that the prediction accuracy does not degrade with the HI longitudinal
separation from Earth. Predicted arrival times are on average within 2.6
± 16.6 h difference of the in situ arrival time, similar to analytical
and numerical modeling, and a true skill statistic of 0.21. We also
discuss various factors that may improve the accuracy of space weather
forecasting using wide-angle heliospheric imager observations. These
results form a first-order approximated baseline of the prediction
accuracy that is possible with HI and other methods used for data by
an operational space weather mission at the Sun-Earth L5 point.

---------------------------------------------------------
Title: Kinematics and shock locations of a spatial resolved solar
type II radio burst with LOFAR.
Authors: Zucca, Pietro; Morosan, Diana; Gallagher, Peter T.; Fallows,
Richard; Rouillard, Alexis; Magdalenić, Jasmina; Vocks, Christian;
Marqué, Christophe; Klein, Karl-Ludwig; Mann, Gottfried
2017EGUGA..1915801Z Altcode:
Type II radio bursts are evidence of shocks in the solar atmosphere
emitting radio waves ranging from metric to kilometric lengths. These
shocks may be associated with coronal mass ejections (CMEs) reaching
super-Alfvènic speeds. Radio imaging of the decameter wavelengths is
now possible with the Low Frequency Array (LOFAR), opening a new radio
window to study coronal radio shocks leaving the inner solar corona
and entering the interplanetary medium and understand their association
with CMEs. Here, we study a coronal shock associated with a CME and type
II radio burst to determine the location where the shock is triggered
in relation to the propagating CME, the ambient medium Alfvèn speed
and the orientation of the coronal magnetic field. The type II shock
imaging and spectra were obtained using 91 simultaneous tied-array
beams of LOFAR while the CME was observed by the Large Angle and
Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric
Observatory (SOHO). Using the tied array beam observing mode of LOFAR
we were able to locate the type II radio shock position between 45 and
75 MHz and relate it to the expanding flank of a CME leaving the inner
corona. The radio emission associated with the type II shock was found
to be located at the flank of the CME in a region where the mach number
is between 1.5 to 2.0 and the shock geometry is quasi-perpendicular.

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Title: CME properties and solar source region characteristics -
HELCATS results
Authors: Bothmer, Volker; Mrotzek, Niclas; Murray, Sophie; Gallagher,
Peter; Barnes, David; Davies, Jackie; Harrison, Richard
2017EGUGA..19.5107B Altcode:
One objective of the EU FP7 project HELCATS is to derive and
catalogue the characteristics of CMEs observed with the STEREO/COR2
&amp; HI imagers based on geometrical and forward modelling. Here
we present the results of the analysis of a subset of the 122 CME
events that have been dynamically modelled with the GCS-method in
the COR2 field of view and which are compiled in the KINCAT database
at http://www.affects-fp7.eu/helcats-database/database.php. The
CME properties, such as speeds, masses, angular widths, as derived
from modelling, are compared with magnetic field properties of the
corresponding solar source active region, such as magnetic flux,
area, and polarity line characteristics. The results show which solar
parameters define the structure of CMEs at distances around 12 solar
radii and how they can be used for space weather forecast services.

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Title: Connecting Coronal Mass Ejections to their Solar Active
Region Sources
Authors: Murray, Sophie; Gallagher, Peter; Carley, Eoin; Zucca, Pietro
2017EGUGA..19.4923M Altcode:
Severe space weather events have the potential to significantly
impact a range of vital technologies on Earth and in near-Earth
space. Understanding the processes involved in the solar eruptions that
cause these events is imperative to provide accurate space weather
forecasts. Coronal mass ejections (CMEs) and other solar eruptive
phenomena can be physically linked by combining data from a multitude
of ground-based and space-based instruments as well as models, however
this can be challenging for automated operational systems. The EU FP7
HELCATS project provides data from heliospheric imaging onboard the
two NASA/STEREO spacecraft in order to track the evolution of CMEs in
the inner heliosphere. From a catalogue of nearly 2,000 CME events, an
automated algorithm has been developed to connect the CMEs observed by
STEREO to any corresponding solar flares and active region sources on
the solar surface. CME kinematic properties, such as speed and angular
width, are compared with active region magnetic field properties, such
as magnetic flux, area, and polarity line characteristics. This large
database provides insight into the link between CME and flare events,
as well as characteristics of eruptive active regions. The automated
method may prove useful for future operational CME forecasting efforts.

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Title: A Catalogue of Coronal Mass Ejections Observed by the STEREO
Heliospheric Imagers: Results from HELCATS
Authors: Barnes, David; Davies, Jackie; Harrison, Richard; Perry,
Chris; Möstl, Christian; Rouillard, Alexis; Bothmer, Volker;
Rodriguez, Luciano; Eastwood, Jonathan; Kilpua, Emilia; Gallagher,
Peter
2017EGUGA..19.8160B Altcode:
The wide fields of view provided by the STEREO Heliospheric Imagers
(HIs) allow far greater coverage of Coronal Mass Ejections (CMEs) than
are typically available from coronagraph observations. As part of the EU
FP7 HELCATS (Heliospheric Cataloguing, Analysis and Techniques Service)
project we present a comprehensive catalogue of CMEs that are observed
in HI data, throughout the lifetime of the instruments. This spans
the period from April 2007 to September 2014 for both STEREO-A and -B,
with additional STEREO-A observations continuing from October 2015 to
present, covering the majority of solar cycle 24. A subset of these
CMEs are tracked through the HI fields of view, to which we apply both
single-spacecraft and stereoscopic models to determine CME kinematic
properties such as propagation directions, speeds and accelerations. The
statistical properties of these results are discussed and they are
compared with coronagraph observations during the same period.

---------------------------------------------------------
Title: Long-Term Tracking of Corotating Density Structures Using
Heliospheric Imaging (catalogue of CIRs during 2007-2014)
Authors: Plotnikov, Illya; Rouillard, Alexis P.; Davies, Jackie;
Botmer, Volker; Eastwood, Jonathan; Gallagher, Peter; Harrison,
Richard; Kilpua, Emilia; Möstl, Christian C.; Perry, Chris; Rodriguez,
Luciano; Lavraud, Benoit; Genot, Vincent; Pinto, Rui; Sanchez-Diaz,
Eduardo
2017EGUGA..19.4486P Altcode:
The systematic monitoring of the solar wind in high-cadence and
high-resolution heliospheric images taken by the Solar-Terrestrial
Relation Observatory (STEREO) spacecraft permits the study of the
spatial and temporal evolution of variable solar wind flows from
the Sun out to 1 AU, and beyond. As part of the EU Framework 7 (FP7)
Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS)
project, we have generated a catalogue listing the properties of more
than 190 corotating structures well-observed in images taken by the
Heliospheric Imager (HI) instruments on-board STEREO-A (ST-A). Based
on this catalogue, we present here one of very few long-term analyses
of solar wind structures advected by the background solar wind. We
concentrate on the subset of plasma density structures clearly
identified inside corotating structures. This analysis confirms that
most of the corotating density structures detected by the heliospheric
imagers comprises a series of density inhomogeneities advected by the
slow solar wind that eventually become entrained by stream interaction
regions. We have derived the spatial-temporal evolution of each
of these corotating density structures by using a well-established
fitting technique. The mean radial propagation speed of the corotating
structures is found to be 311 ± 31 km s-1. We show that the speeds of
the corotating density structures derived using our fitting technique
track well the long-term variation of the radial speed of the slow
solar wind during solar minimum years (2007-2008). Furthermore, we
demonstrate that these features originate near the coronal neutral
line that eventually becomes the heliospheric current sheet.

---------------------------------------------------------
Title: Overview of the HELCATS project
Authors: Harrison, Richard; Davies, Jackie; Perry, Chris; Moestl,
Christian; Rouillard, Alexis; Bothmer, Volker; Rodriguez, Luciano;
Eastwood, Jonathan; Kilpua, Emilia; Gallagher, Peter; Odstrcil, Dusan
2017EGUGA..19.5296H Altcode:
Understanding solar wind evolution is fundamental to advancing our
knowledge of energy and mass transport in the solar system, whilst
also being crucial to space weather and its prediction. The advent of
truly wide-angle heliospheric imaging has revolutionised the study of
solar wind evolution, by enabling direct and continuous observation
of both transient and background components of the solar wind as
they propagate from the Sun to 1 AU and beyond. The EU-funded FP7
Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS)
project combines European expertise in heliospheric imaging, built up
over the last decade in particular through lead involvement in NASA's
STEREO mission, with expertise in solar and coronal imaging as well
as the interpretation of in-situ and radio diagnostic measurements of
solar wind phenomena. HELCATS involves: (1) cataloguing of transient
(coronal mass ejections) and background (stream/corotating interaction
regions) solar wind structures observed by the STEREO/Heliospheric
Imagers, including estimates of their kinematic properties based on
a variety of modelling techniques; (2) verifying these kinematic
properties through comparison with solar source observations and
in-situ measurements at multiple points throughout the heliosphere;
(3) assessing the potential for initialising numerical models based
on the derived kinematic properties of transient and background
solar wind components; (4) assessing the complementarity of radio
observations (Type II radio bursts and interplanetary scintillation)
in the detection and analysis of heliospheric structure in combination
with heliospheric imaging observations. We provide an overview of the
achievements of the HELCATS project, as it reaches its conclusion, and
present selected results that seek to illustrate the value and legacy of
this unprecedented, coordinated study of structures in the heliosphere.

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Title: Detection and Interpretation of Long-lived X-Ray Quasi-periodic
Pulsations in the X-class Solar Flare on 2013 May 14
Authors: Dennis, Brian R.; Tolbert, Anne K.; Inglis, Andrew; Ireland,
Jack; Wang, Tongjiang; Holman, Gordon D.; Hayes, Laura A.; Gallagher,
Peter T.
2017ApJ...836...84D Altcode: 2017arXiv170603689D
Quasi-periodic pulsations (QPP) seen in the time derivative of the
GOES soft X-ray light curves are analyzed for the X3.2 event on 2013
May 14. The pulsations are apparent for a total of at least two hours
from the impulsive phase to well into the decay phase, with a total
of 163 distinct pulses evident to the naked eye. A wavelet analysis
shows that the characteristic timescale of these pulsations increases
systematically from ∼25 s at 01:10 UT, the time of the GOES peak,
to ∼100 s at 02:00 UT. A second “ridge” in the wavelet power
spectrum, most likely associated with flaring emission from a different
active region, shows an increase from ∼40 s at 01:40 UT to ∼100 s
at 03:10 UT. We assume that the QPP that produced the first ridge result
from vertical kink-mode oscillations of the newly formed loops following
magnetic reconnection in the coronal current sheet. This allows us to
estimate the magnetic field strength as a function of altitude given the
density, loop length, and QPP timescale as functions of time determined
from the GOES light curves and Ramaty High Energy Solar Spectroscopic
Imager (RHESSI) images. The calculated magnetic field strength of the
newly formed loops ranges from ∼500 G at an altitude of 24 Mm to a low
value of ∼10 G at 60 Mm, in general agreement with the expected values
at these altitudes. Fast sausage-mode oscillations are also discussed
and cannot be ruled out as an alternate mechanism for producing the QPP.

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Title: Characteristics of type III radio bursts and solar S bursts
Authors: Morosan, D. E.; Gallagher, P. T.
2017pre8.conf..357M Altcode: 2018arXiv180210460M
The Sun is an active source of radio emission which is often associated
with the acceleration of electrons arising from processes such as solar
flares and coronal mass ejections (CMEs). At low radio frequencies
(&lt;100 MHz), numerous solar S bursts (where S stands for short)
and storms of type III radio bursts have been observed, that are not
directly relates to flares and CMEs. Here, we expand our understanding
on the spectral characteristic of these two different types of radio
bursts based on observations from the Low Frequency Array (LOFAR). On
9 July 2013, over 3000 solar S bursts accompanied by over 800 type
III radio bursts were observed over a time period of 8 hours. The
characteristics of type III radio bursts presented here are consistent
with previous studies. S bursts are shown to be different compared
to type III bursts: they show narrow bandwidths, short durations and
drift rates of about 1/2 the drift rate of type III bursts. Both type
III bursts and solar S bursts occur in a region in the corona where
plasma emission is the dominant emission mechanism as determined by
data constrained density and magnetic field models.

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Title: Understanding the Physical Nature of Coronal "EIT Waves"
Authors: Long, D. M.; Bloomfield, D. S.; Chen, P. F.; Downs, C.;
Gallagher, P. T.; Kwon, R. -Y.; Vanninathan, K.; Veronig, A. M.;
Vourlidas, A.; Vršnak, B.; Warmuth, A.; Žic, T.
2017SoPh..292....7L Altcode: 2016arXiv161105505L
For almost 20 years the physical nature of globally propagating waves in
the solar corona (commonly called "EIT waves") has been controversial
and subject to debate. Additional theories have been proposed over the
years to explain observations that did not agree with the originally
proposed fast-mode wave interpretation. However, the incompatibility
of observations made using the Extreme-ultraviolet Imaging Telescope
(EIT) onboard the Solar and Heliospheric Observatory with the fast-mode
wave interpretation was challenged by differing viewpoints from the twin
Solar Terrestrial Relations Observatory spacecraft and data with higher
spatial and temporal resolution from the Solar Dynamics Observatory. In
this article, we reexamine the theories proposed to explain EIT waves
to identify measurable properties and behaviours that can be compared
to current and future observations. Most of us conclude that the
so-called EIT waves are best described as fast-mode large-amplitude
waves or shocks that are initially driven by the impulsive expansion
of an erupting coronal mass ejection in the low corona.

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Title: Observing the Formation of Flare-driven Coronal Rain
Authors: Scullion, E.; Rouppe van der Voort, L.; Antolin, P.;
Wedemeyer, S.; Vissers, G.; Kontar, E. P.; Gallagher, P. T.
2016ApJ...833..184S Altcode: 2016arXiv161009255S
Flare-driven coronal rain can manifest from rapidly cooled plasma
condensations near coronal loop tops in thermally unstable postflare
arcades. We detect five phases that characterize the postflare decay:
heating, evaporation, conductive cooling dominance for ∼120 s,
radiative/enthalpy cooling dominance for ∼4700 s, and finally
catastrophic cooling occurring within 35-124 s, leading to rain
strands with a periodicity of 55-70 s. We find an excellent agreement
between the observations and model predictions of the dominant
cooling timescales and the onset of catastrophic cooling. At the
rain-formation site, we detect comoving, multithermal rain clumps
that undergo catastrophic cooling from ∼1 MK to ∼22,000 K. During
catastrophic cooling, the plasma cools at a maximum rate of 22,700
K s-1 in multiple loop-top sources. We calculated the
density of the extreme-ultraviolet (EUV) plasma from the differential
emission measure of the multithermal source employing regularized
inversion. Assuming a pressure balance, we estimate the density of
the chromospheric component of rain to be 9.21 × 1011
± 1.76 × 1011 cm-3, which is comparable with
quiescent coronal rain densities. With up to eight parallel strands
in the EUV loop cross section, we calculate the mass loss rate from
the postflare arcade to be as much as 1.98 × 1012 ±
4.95 × 1011 g s-1. Finally, we reveal a close
proximity between the model predictions of {10}5.8 K and the
observed properties between {10}5.9 and {10}6.2
K, which defines the temperature onset of catastrophic cooling. The
close correspondence between the observations and numerical models
suggests that indeed acoustic waves (with a sound travel time of 68 s)
could play an important role in redistributing energy and sustaining
the enthalpy-based radiative cooling.

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Title: A Large-Scale Search for Evidence of Quasi-Periodic Pulsations
in Solar Flare X-ray Emission
Authors: Inglis, A. R.; Ireland, J.; Dennis, B. R.; Hayes, L.;
Gallagher, P.
2016AGUFMSH21E2563I Altcode:
The nature of quasi-periodic pulsations in solar flares is poorly
constrained, and critically the general prevalence of such signals
in solar flares is unknown. We present the results of a large-scale,
statistically robust search for evidence of signals consistent with
quasi-periodic pulsations in solar flares, focusing on the 1 - 300s
timescale. We analyse 675 M- and X-class flares observed by GOES in 1-8A
soft X-rays between 2011 February 1 and 2015 December 31. Additionally,
we analyse 209 events in the same time interval observed by Fermi/GBM
in 15-25 keV X-rays. We use a novel model comparison approach, testing
three models applied to the Fourier power spectra of each flare. From
this we determine whether there is evidence for a substantial
enhancement in the Fourier domain that may be consistent with a QPP
signature. Our findings are that 30% of GOES events and 16% of Fermi/GBM
events show signatures consistent with classical interpretations of
QPP. The remaining events are adequately described by single power-law
or broken power-law Fourier power spectra. For both instruments,
a preferred characteristic timescale of 5-30 s was found, with no
dependence on flare magnitude in GOES, and weak dependence in GBM. We
also show that, for events where a detection occurred in both Fermi/GBM
and GOES datasets, similar characteristic timescales were found with
both instruments. We discuss the implications of these results for
our understanding of solar flares and possible QPP mechanisms.

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Title: Solar Magnetic Data Analysis for the FLARECAST Project
Authors: Guerra, J. A.; Park, S. H.; Kontogiannis, I.; Bloomfield,
D.; Gallagher, P.; Georgoulis, M. K.
2016AGUFMSH11C2234G Altcode:
The Flare Likelihood And Region Eruption foreCASTing (FLARECAST) project
is an EU H2020-funded consortium project aiming to develop an advanced
solar flare forecasting system by implementing state-of-the-art
solar data analysis and flare prediction algorithms. The Solar
Physics Group at Trinity College Dublin is in charge of the analysis
of observational data to extract solar active region properties
that serve as input for the prediction algorithms. The calculated
active region properties correspond to a non-exhaustive list of
parameters that have demonstrated a strong flare association, such as
Schrijver's R-value, the Fourier power spectrum exponent, the effective
connected magnetic field (Beff), the horizontal field decay index,
and the weighted length of strong-gradient polarity inversion lines
(WLSG). Parameters were calculated from Spaceweather HMI Active Region
Patch (SHARP) magnetograms, a data product of the Helioseismic and
Magnetic Imager (HMI) magnetograph on the Solar Dynamics Observatory
(SDO). SHARPs provide photospheric vector-magnetic field (B) images
in near-realtime. For this study, results from a statistical study
performed on a robust subsample of the entire SHARP dataset will be
presented. In the framework of the FLARECAST predictor component,
this study focuses, for the first time, on differences between
parameter values found when the radial magnetic field component, Br,
is used instead of the line-of-sight component, Blos. The effect of
active region longitudinal position is discussed, as well as the flare
association of the properties.

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Title: Radio Diagnostics of Electron Acceleration Sites During the
Eruption of a Flux Rope in the Solar Corona
Authors: Carley, Eoin P.; Vilmer, Nicole; Gallagher, Peter T.
2016ApJ...833...87C Altcode: 2016arXiv160901463C
Electron acceleration in the solar corona is often associated with
flares and the eruption of twisted magnetic structures known as
flux ropes. However, the locations and mechanisms of such particle
acceleration during the flare and eruption are still subject to much
investigation. Observing the exact sites of particle acceleration can
help confirm how the flare and eruption are initiated and how they
evolve. Here we use the Atmospheric Imaging Assembly to analyze a flare
and erupting flux rope on 2014 April 18, while observations from the
Nançay Radio Astronomy Facility allow us to diagnose the sites of
electron acceleration during the eruption. Our analysis shows evidence
of a pre-formed flux rope that slowly rises and becomes destabilized
at the time of a C-class flare, plasma jet, and the escape of ≳75
keV electrons from the rope center into the corona. As the eruption
proceeds, continued acceleration of electrons with energies of ∼5
keV occurs above the flux rope for a period over 5 minutes. At the
flare peak, one site of electron acceleration is located close to
the flare site, while another is driven by the erupting flux rope
into the corona at speeds of up to 400 km s-1. Energetic
electrons then fill the erupting volume, eventually allowing the
flux rope legs to be clearly imaged from radio sources at 150-445
MHz. Following the analysis of Joshi et al. (2015), we conclude
that the sites of energetic electrons are consistent with flux rope
eruption via a tether cutting or flux cancellation scenario inside a
magnetic fan-spine structure. In total, our radio observations allow
us to better understand the evolution of a flux rope eruption and its
associated electron acceleration sites, from eruption initiation to
propagation into the corona.

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Title: Geomagnetically induced currents in the Irish power network
during geomagnetic storms
Authors: Blake, Seán. P.; Gallagher, Peter T.; McCauley, Joe; Jones,
Alan G.; Hogg, Colin; Campanyà, Joan; Beggan, Ciarán. D.; Thomson,
Alan W. P.; Kelly, Gemma S.; Bell, David
2016SpWea..14.1136B Altcode: 2016arXiv161108587B
Geomagnetically induced currents (GICs) are a well-known terrestrial
space weather hazard. They occur in power transmission networks and
are known to have adverse effects in both high-latitude and midlatitude
countries. Here we study GICs in the Irish power transmission network
(geomagnetic latitude 54.7-58.5°N) during five geomagnetic storms
(6-7 March 2016, 20-21 December 2015, 17-18 March 2015, 29-31
October 2003, and 13-14 March 1989). We simulate electric fields
using a plane wave method together with two ground resistivity
models, one of which is derived from magnetotelluric measurements
(magnetotelluric (MT) model). We then calculate GICs in the 220, 275,
and 400 kV transmission network. During the largest of the storm periods
studied, the peak electric field was calculated to be as large as 3.8
V km-1, with associated GICs of up to 23 A using our MT
model. Using our homogenous resistivity model, those peak values were
1.46 V km-1 and 25.8 A. We find that three 400 and 275 kV
substations are the most likely locations for the Irish transformers
to experience large GICs.

---------------------------------------------------------
Title: A Large-scale Search for Evidence of Quasi-periodic Pulsations
in Solar Flares
Authors: Inglis, A. R.; Ireland, J.; Dennis, B. R.; Hayes, L.;
Gallagher, P.
2016ApJ...833..284I Altcode: 2016arXiv161007454I
The nature of quasi-periodic pulsations (QPP) in solar flares is
poorly constrained, and critically the general prevalence of such
signals in solar flares is unknown. Therefore, we perform a large-scale
search for evidence of signals consistent with QPP in solar flares,
focusing on the 1-300 s timescale. We analyze 675 M- and X-class flares
observed by the Geostationary Operational Environmental Satellite (GOES)
series in 1-8 Å soft X-rays between 2011 February 1 and 2015 December
31. Additionally, over the same era we analyze Fermi/Gamma-ray Burst
Monitor (GBM) 15-25 keV X-ray data for each of these flares associated
with a Fermi/GBM solar flare trigger, a total of 261 events. Using
a model comparison method, we determine whether there is evidence
for a substantial enhancement in the Fourier power spectrum that may
be consistent with a QPP signature, based on three tested models;
a power-law plus a constant, a broken power-law plus constant, and a
power-law-plus-constant with an additional QPP signature component. From
this, we determine that ∼30% of GOES events and ∼8% of Fermi/GBM
events show strong signatures consistent with classical interpretations
of QPP. For the remaining events either two or more tested models
cannot be strongly distinguished from each other, or the events are
well-described by single power-law or broken power-law Fourier power
spectra. For both instruments, a preferred characteristic timescale of
∼5-30 s was found in the QPP-like events, with no dependence on flare
magnitude in either GOES or GBM data. We also show that individual
events in the sample show similar characteristic timescales in both
GBM and GOES data sets. We discuss the implications of these results
for our understanding of solar flares and possible QPP mechanisms.

---------------------------------------------------------
Title: A Catalogue of Geometrically-Modelled Coronal Mass Ejections
Observed by the STEREO Heliospheric Imagers
Authors: Barnes, D.; Davies, J. A.; Harrison, R. A.; Perry, C. H.;
Moestl, C.; Rouillard, A.; Bothmer, V.; Rodriguez, L.; Eastwood,
J. P.; Kilpua, E.; Gallagher, P.
2016AGUFMSH31B2588B Altcode:
We present a catalogue of Coronal Mass Ejections (CMEs) observed by the
Heliospheric Imagers (HIs) onboard the two NASA STEREO spacecraft. This
catalogue contains all CMEs observed during the operational phase of the
STEREO mission, April 2007 to September 2014, for both spacecraft and
resumes from November 2015 for STEREO-A. These CMEs are tracked using
time-elongation plots through the HI-1 and HI-2 fields of view and to
them we apply geometric models to determine their kinematic properties,
such as speed, propagation direction and launch time. A subset of
these CMEs, which are observed simultaneously by both spacecraft,
are identified and to which stereoscopic modelling techniques are
applied. The statistical properties of these catalogues are discussed
as are their results compared to existing CME catalogues covering the
same periods. This work is carried out as part of the EU FP7 HELCATS
(Heliospheric Cataloguing, Analysis and Techniques Service) project.

---------------------------------------------------------
Title: A Comparison of Flare Forecasting Methods. I. Results from
the “All-Clear” Workshop
Authors: Barnes, G.; Leka, K. D.; Schrijver, C. J.; Colak, T.;
Qahwaji, R.; Ashamari, O. W.; Yuan, Y.; Zhang, J.; McAteer, R. T. J.;
Bloomfield, D. S.; Higgins, P. A.; Gallagher, P. T.; Falconer, D. A.;
Georgoulis, M. K.; Wheatland, M. S.; Balch, C.; Dunn, T.; Wagner, E. L.
2016ApJ...829...89B Altcode: 2016arXiv160806319B
Solar flares produce radiation that can have an almost immediate effect
on the near-Earth environment, making it crucial to forecast flares
in order to mitigate their negative effects. The number of published
approaches to flare forecasting using photospheric magnetic field
observations has proliferated, with varying claims about how well
each works. Because of the different analysis techniques and data
sets used, it is essentially impossible to compare the results from
the literature. This problem is exacerbated by the low event rates of
large solar flares. The challenges of forecasting rare events have long
been recognized in the meteorology community, but have yet to be fully
acknowledged by the space weather community. During the interagency
workshop on “all clear” forecasts held in Boulder, CO in 2009,
the performance of a number of existing algorithms was compared
on common data sets, specifically line-of-sight magnetic field and
continuum intensity images from the Michelson Doppler Imager, with
consistent definitions of what constitutes an event. We demonstrate
the importance of making such systematic comparisons, and of using
standard verification statistics to determine what constitutes a good
prediction scheme. When a comparison was made in this fashion, no one
method clearly outperformed all others, which may in part be due to the
strong correlations among the parameters used by different methods to
characterize an active region. For M-class flares and above, the set
of methods tends toward a weakly positive skill score (as measured
with several distinct metrics), with no participating method proving
substantially better than climatological forecasts.

---------------------------------------------------------
Title: Understanding the Physical Nature of Coronal "EIT Waves"
Authors: Long, D. M.; Bloomfield, D. S.; Chen, P. -F.; Downs,
C.; Gallagher, P. T.; Kwon, R. -Y.; Vanninathan, K.; Veronig, A.;
Vourlidas, A.; Vrsnak, B.; Warmuth, A.; Zic, T.
2016usc..confE..24L Altcode:
For almost 20 years the physical nature of globally-propagating waves
in the solar corona (commonly called "EIT waves") has been controversial
and subject to debate. Additional theories have been proposed throughout
the years to explain observations that did not fit with the originally
proposed fast-mode wave interpretation. However, the incompatibility
of observations made using the Extreme-ultraviolet Imaging Telescope
(EIT) on the Solar and Heliospheric Observatory with the fast-mode
wave interpretation have been challenged by differing viewpoints
from the Solar Terrestrial Relations Observatory spacecraft and higher
spatial/temporal resolution data from the Solar Dynamics Observatory. In
this paper, we reexamine the theories proposed to explain "EIT waves"
to identify measurable properties and behaviours that can be compared
to current and future observations. Most of us conclude that "EIT
waves" are best described as fast-mode large-amplitude waves/shocks,
which are initially driven by the impulsive expansion of an erupting
coronal mass ejection in the low corona.

---------------------------------------------------------
Title: Flaring Rates and the Evolution of Sunspot Group McIntosh
Classifications
Authors: McCloskey, Aoife E.; Gallagher, Peter T.; Bloomfield, D. Shaun
2016SoPh..291.1711M Altcode: 2016arXiv160700903M; 2016SoPh..tmp..116M
Sunspot groups are the main source of solar flares, with the energy
to power them being supplied by magnetic-field evolution (e.g. flux
emergence or twisting/shearing). To date, few studies have investigated
the statistical relation between sunspot-group evolution and flaring,
with none considering evolution in the McIntosh classification
scheme. Here we present a statistical analysis of sunspot groups from
Solar Cycle 22, focusing on 24-hour changes in the three McIntosh
classification components. Evolution-dependent ≥C 1.0 , ≥M 1.0 ,
and ≥X 1.0 flaring rates are calculated, leading to the following
results: i) flaring rates become increasingly higher for greater
degrees of upward evolution through the McIntosh classes, with the
opposite found for downward evolution; ii) the highest flaring rates
are found for upward evolution from larger, more complex, classes
(e.g. Zurich D- and E-classes evolving upward to F-class produce
≥C 1.0 rates of 2.66 ±0.28 and 2.31 ±0.09 flares per 24 hours,
respectively); iii) increasingly complex classes give higher rates for
all flare magnitudes, even when sunspot groups do not evolve over 24
hours. These results support the hypothesis that injection of magnetic
energy by flux emergence (i.e. increasing in Zurich or compactness
classes) leads to a higher frequency and magnitude of flaring.

---------------------------------------------------------
Title: Quasi-periodic Pulsations during the Impulsive and Decay
phases of an X-class Flare
Authors: Hayes, L. A.; Gallagher, P. T.; Dennis, B. R.; Ireland, J.;
Inglis, A. R.; Ryan, D. F.
2016ApJ...827L..30H Altcode: 2016arXiv160706957H
Quasi-periodic pulsations (QPPs) are often observed in X-ray emission
from solar flares. To date, it is unclear what their physical origins
are. Here, we present a multi-instrument investigation of the nature
of QPP during the impulsive and decay phases of the X1.0 flare of 2013
October 28. We focus on the character of the fine structure pulsations
evident in the soft X-ray (SXR) time derivatives and compare this
variability with structure across multiple wavelengths including hard
X-ray and microwave emission. We find that during the impulsive phase
of the flare, high correlations between pulsations in the thermal and
non-thermal emissions are seen. A characteristic timescale of ∼20 s is
observed in all channels and a second timescale of ∼55 s is observed
in the non-thermal emissions. SXR pulsations are seen to persist into
the decay phase of this flare, up to 20 minutes after the non-thermal
emission has ceased. We find that these decay phase thermal pulsations
have very small amplitude and show an increase in characteristic
timescale from ∼40 s up to ∼70 s. We interpret the bursty nature
of the co-existing multi-wavelength QPPs during the impulsive phase
in terms of episodic particle acceleration and plasma heating. The
persistent thermal decay phase QPPs are most likely connected with
compressive magnetohydrodynamic processes in the post-flare loops such
as the fast sausage mode or the vertical kink mode.

---------------------------------------------------------
Title: Long-Term Tracking of Corotating Density Structures Using
Heliospheric Imaging
Authors: Plotnikov, I.; Rouillard, A. P.; Davies, J. A.; Bothmer,
V.; Eastwood, J. P.; Gallagher, P.; Harrison, R. A.; Kilpua, E.;
Möstl, C.; Perry, C. H.; Rodriguez, L.; Lavraud, B.; Génot, V.;
Pinto, R. F.; Sanchez-Diaz, E.
2016SoPh..291.1853P Altcode: 2016SoPh..tmp..118P; 2016arXiv160601127P
The systematic monitoring of the solar wind in high-cadence and
high-resolution heliospheric images taken by the Solar-Terrestrial
Relation Observatory (STEREO) spacecraft permits the study of the
spatial and temporal evolution of variable solar wind flows from
the Sun out to 1 AU, and beyond. As part of the EU Framework 7 (FP7)
Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS)
project, we have generated a catalog listing the properties of 190
corotating structures well-observed in images taken by the Heliospheric
Imager (HI) instruments onboard STEREO-A (ST-A). Based on this catalog,
we present here one of very few long-term analyses of solar wind
structures advected by the background solar wind. We concentrate on the
subset of plasma density structures clearly identified inside corotating
structures. This analysis confirms that most of the corotating density
structures detected by the heliospheric imagers comprises a series
of density inhomogeneities advected by the slow solar wind that
eventually become entrained by stream interaction regions. We have
derived the spatial-temporal evolution of each of these corotating
density structures by using a well-established fitting technique. The
mean radial propagation speed of the corotating structures is found
to be 311 ±31 kms−1. Such a low mean value corresponds
to the terminal speed of the slow solar wind rather than the speed of
stream interfaces, which is typically intermediate between the slow and
fast solar wind speeds (∼400 kms−1). Using our fitting
technique, we predicted the arrival time of each corotating density
structure at different probes in the inner heliosphere. We find that our
derived speeds are systematically lower by ∼100 kms−1
than those measured in situ at the predicted impact times. Moreover,
for cases when a stream interaction region is clearly detected in situ
at the estimated impact time, we find that our derived speeds are lower
than the speed of the stream interface measured in situ by an average
of 55 kms−1 at ST-A and 84 kms−1 at STEREO-B
(ST-B). We show that the speeds of the corotating density structures
derived using our fitting technique track well the long-term variation
of the radial speed of the slow solar wind during solar minimum years
(2007 - 2008). Furthermore, we demonstrate that these features originate
near the coronal neutral line that eventually becomes the heliospheric
current sheet.

---------------------------------------------------------
Title: Enabling Solar Flare Forecasting at an Unprecedented Level:
the FLARECAST Project
Authors: Georgoulis, Manolis K.; Pariat, Etienne; Massone, Anna
Maria; Vilmer, Nicole; Jackson, David; Buchlin, Eric; Csillaghy,
Andre; Bommier, Veronique; Kontogiannis, Ioannis; Gallagher, Peter;
Gontikakis, Costis; Guennou, Chloé; Murray, Sophie; Bloomfield,
D. Shaun; Alingery, Pablo; Baudin, Frederic; Benvenuto, Federico;
Bruggisser, Florian; Florios, Konstantinos; Guerra, Jordan; Park,
Sung-Hong; Perasso, Annalisa; Piana, Michele; Sathiapal, Hanna;
Soldati, Marco; Von Stachelski, Samuel; Argoudelis, Vangelis;
Caminade, Stephane
2016cosp...41E.657G Altcode:
We attempt a brief but informative description of the Flare
Likelihood And Region Eruption Forecasting (FLARECAST) project,
European Commission's first large-scale investment to explore the
limits of reliability and accuracy for the forecasting of major solar
flares. The consortium, objectives, and first results of the project
- featuring an openly accessible, interactive flare forecasting
facility by the end of 2017 - will be outlined. In addition, we will
refer to the so-called "explorative research" element of project,
aiming to connect solar flares with coronal mass ejections (CMEs)
and possibly pave the way for CME, or eruptive flare, prediction. We
will also emphasize the FLARECAST modus operandi, namely the diversity
of expertise within the consortium that independently aims to science,
infrastructure development and dissemination, both to stakeholders and
to the general public. Concluding, we will underline that the FLARECAST
project responds squarely to the joint COSPAR - ILWS Global Roadmap
to shield society from the adversities of space weather, addressing
its primary goal and, in particular, its Research Recommendations
1, 2 and 4, Teaming Recommendations II and III, and Collaboration
Recommendations A, B, and D. The FLARECAST project has received funding
from the European Union's Horizon 2020 research and innovation programme
under grant agreement No. 640216.

---------------------------------------------------------
Title: Conditions for electron-cyclotron maser emission in the
solar corona
Authors: Morosan, D. E.; Zucca, P.; Bloomfield, D. S.; Gallagher, P. T.
2016A&A...589L...8M Altcode: 2016arXiv160404788M
Context. The Sun is an active source of radio emission ranging from
long duration radio bursts associated with solar flares and coronal
mass ejections to more complex, short duration radio bursts such as
solar S bursts, radio spikes and fibre bursts. While plasma emission is
thought to be the dominant emission mechanism for most radio bursts,
the electron-cyclotron maser (ECM) mechanism may be responsible
for more complex, short-duration bursts as well as fine structures
associated with long-duration bursts. Aims: We investigate the
conditions for ECM in the solar corona by considering the ratio of the
electron plasma frequency ωp to the electron-cyclotron
frequency Ωe. The ECM is theoretically possible when
ωp/ Ωe&lt; 1. Methods: Two-dimensional
electron density, magnetic field, plasma frequency, and electron
cyclotron frequency maps of the off-limb corona were created using
observations from SDO/AIA and SOHO/LASCO, together with potential
field extrapolations of the magnetic field. These maps were then used
to calculate ωp/Ωe and Alfvén velocity maps
of the off-limb corona. Results: We found that the condition
for ECM emission (ωp/ Ωe&lt; 1) is possible at
heights &lt;1.07 R⊙ in an active region near the limb;
that is, where magnetic field strengths are &gt;40 G and electron
densities are &gt;3 × 108 cm-3. In addition, we
found comparatively high Alfvén velocities (&gt;0.02c or &gt;6000 km
s-1) at heights &lt;1.07 R⊙ within the active
region. Conclusions: This demonstrates that the condition for
ECM emission is satisfied within areas of the corona containing large
magnetic fields, such as the core of a large active region. Therefore,
ECM could be a possible emission mechanism for high-frequency radio
and microwave bursts.

---------------------------------------------------------
Title: Quasi-Periodic Pulsations (QPP) in a Long-Duration Flare
Authors: Dennis, Brian R.; Tolbert, Anne K.; Inglis, Andrew R.;
Ireland, Jack; Wang, Tongjiang; Holman, Gordon D.; Hayes, Laura Ann;
Gallagher, Peter T.
2016SPD....47.0605D Altcode:
We have detected 163 distinct peaks in the time derivative of the
GOES light curve of the X-class flare on 2013 May 14. QPP were
detected for the first two hours of this 8-hour event. The thermal
X-ray source revealed in RHESSI 6 - 12 keV images eventually rose
to an altitude of over 60 km at a rate of 1.6 km/s. The mean QPP
time scale increased from ~10 s during the impulsive phase to ~100
s some two hours later. Interpreting the QPP as being produced by
vertical kink mode oscillations has allowed estimates to be made of
the coronal magnetic field strength as a function of altitude. This
uses the measured QPP time scales with the length and densities of
the oscillating loops determined from the emission measure and source
volume given by the RHESSI imaging spectroscopy observations. Applying
this analysis to other events will further test the idea that vertical
kink-mode oscillations are the source of QPP during both the impulsive
and decay phases. If this origin is established, then QPP can be used as
a diagnostic of the conditions in the corona close to the energy release
site. In particular, it should be possible to obtain estimates of the
Alfven speed, density, beta value, and magnetic field strength in the
region of the soft X-ray emitting plasma. During the impulsive phase,
other processes, presumably connected to the energy release process
itself, can dominate to produce the more chaotic impulsive nature of
the emission light curve.

---------------------------------------------------------
Title: HELCATS - Heliospheric Cataloguing, Analysis and Techniques
Service
Authors: Harrison, Richard; Davies, Jackie; Perry, Chris; Moestl,
Christian; Rouillard, Alexis; Bothmer, Volker; Rodriguez, Luciano;
Eastwood, Jonathan; Kilpua, Emilia; Gallagher, Peter
2016EGUGA..1810220H Altcode:
Understanding the evolution of the solar wind is fundamental to
advancing our knowledge of energy and mass transport in the solar
system, rendering it crucial to space weather and its prediction. The
advent of truly wide-angle heliospheric imaging has revolutionised the
study of both transient (CMEs) and background (SIRs/CIRs) solar wind
plasma structures, by enabling their direct and continuous observation
out to 1 AU and beyond. The EU-funded FP7 HELCATS project combines
European expertise in heliospheric imaging, built up in particular
through lead involvement in NASA's STEREO mission, with expertise in
solar and coronal imaging as well as in-situ and radio measurements
of solar wind phenomena, in a programme of work that will enable a
much wider exploitation and understanding of heliospheric imaging
observations. With HELCATS, we are (1.) cataloguing transient and
background solar wind structures imaged in the heliosphere by STEREO/HI,
since launch in late October 2006 to date, including estimates of their
kinematic properties based on a variety of established techniques
and more speculative, approaches; (2.) evaluating these kinematic
properties, and thereby the validity of these techniques, through
comparison with solar source observations and in-situ measurements
made at multiple points throughout the heliosphere; (3.) appraising
the potential for initialising advanced numerical models based on
these kinematic properties; (4.) assessing the complementarity of radio
observations (in particular of Type II radio bursts and interplanetary
scintillation) in combination with heliospheric imagery. We will,
in this presentation, provide an overview of progress from the first
18 months of the HELCATS project.

---------------------------------------------------------
Title: Performance of Major Flare Watches from the Max Millennium
Program (2001 - 2010)
Authors: Bloomfield, D. S.; Gallagher, P. T.; Marquette, W. H.;
Milligan, R. O.; Canfield, R. C.
2016SoPh..291..411B Altcode: 2015arXiv151204518B; 2016SoPh..tmp....1B
The physical processes that trigger solar flares are not well
understood, and significant debate remains around processes governing
particle acceleration, energy partition, and particle and energy
transport. Observations at high resolution in energy, time, and
space are required in multiple energy ranges over the whole course of
many flares to build an understanding of these processes. Obtaining
high-quality, co-temporal data from ground- and space- based instruments
is crucial to achieving this goal and was the primary motivation for
starting the Max Millennium program and Major Flare Watch (MFW) alerts,
aimed at coordinating observations of all flares ≥ X1 GOES X-ray
classification (including those partially occulted by the limb). We
present a review of the performance of MFWs from 1 February 2001 to
31 May 2010, inclusive, which finds that (1) 220 MFWs were issued
in 3407 days considered (6.5 % duty cycle), with these occurring in
32 uninterrupted periods that typically last 2 - 8 days; (2) 56%
of flares ≥ X1 were caught, occurring in 19 % of MFW days; (3)
MFW periods ended at suitable times, but substantial gain could have
been achieved in percentage of flares caught if periods had started
24 h earlier; (4) MFWs successfully forecast X-class flares with a
true skill statistic (TSS) verification metric score of 0.500, that is
comparable to a categorical flare/no-flare interpretation of the NOAA
Space Weather Prediction Centre probabilistic forecasts (TSS = 0.488).

---------------------------------------------------------
Title: Automatic Detection of Magnetic δ in Sunspot Groups
Authors: Padinhatteeri, Sreejith; Higgins, Paul A.; Shaun Bloomfield,
D.; Gallagher, Peter T.
2016SoPh..291...41P Altcode: 2015arXiv151006413P; 2015SoPh..tmp..184P
Large and magnetically complex sunspot groups are known to be
associated with flares. To date, the Mount Wilson scheme has been used
to classify sunspot groups based on their morphological and magnetic
properties. The most flare-prolific class, the δ sunspot group, is
characterised by opposite-polarity umbrae within a common penumbra,
separated by less than 2∘. In this article, we present
a new system, called the Solar Monitor Active Region Tracker-Delta
Finder (SMART-DF), which can be used to automatically detect and
classify magnetic δ s in near-realtime. Using continuum images
and magnetograms from the Helioseismic and Magnetic Imager (HMI)
onboard NASA's Solar Dynamics Observatory (SDO), we first estimate
distances between opposite-polarity umbrae. Opposite-polarity pairs
with distances of less that 2∘ are then identified,
and if these pairs are found to share a common penumbra, they are
identified as a magnetic δ configuration. The algorithm was compared
to manual δ detections reported by the Space Weather Prediction
Center (SWPC), operated by the National Oceanic and Atmospheric
Administration (NOAA). SMART-DF detected 21 out of 23 active regions
(ARs) that were marked as δ spots by NOAA during 2011 - 2012 (within
±60∘ longitude). SMART-DF in addition detected five ARs
that were not announced as δ spots by NOAA. The near-realtime operation
of SMART-DF resulted in many δ s being identified in advance of NOAA's
daily notification. SMART-DF will be integrated into SolarMonitor
(www.solarmonitor.org) and the near-realtime information will be
available to the public.

---------------------------------------------------------
Title: Low Frequency Radio Observations of Bi-directional Electron
Beams in the Solar Corona
Authors: Carley, E.; Reid, H.; Vilmer, N.; Gallagher, P.
2015AGUFMSH22B..01C Altcode:
The radio signature of a shock travelling through the solar corona
is known as a type II solar radio burst. In rare cases, these bursts
can exhibit a fine structure known as 'herringbones' which are a
direct indicator of particle acceleration occurring at the shock
front. However, few studies have been performed on herringbones and
the details of the underlying particle acceleration processes are
unknown. Here, we use an image processing technique known as the Hough
transform to statistically analyse the herringbone fine structure in
a radio burst at 20-90MHz observed from the Rosse Solar-Terrestrial
Observatory on 2011 September 22. We identify 188 individual bursts
which are signatures of bi-directional electron beams continuously
accelerated to speeds of 0.16 c. This occurs at a shock acceleration
site initially at a constant altitude of 0.6 Rsun in the corona,
followed by a shift to 0.5 Rsun. The anti-sunward beams travel a
distance of 170 Mm (and possibly further) away from the acceleration
site, while those travelling toward the sun come to a stop sooner,
reaching a smaller distance of 112 Mm. We show that the stopping
distance for the sunward beams may depend on the total number density
and the velocity of the beam. Our study concludes that a detailed
statistical analysis of herringbone fine structure can provide
information on the physical properties of the corona which lead to
these relatively rare radio bursts.

---------------------------------------------------------
Title: HELCATS - Heliospheric Cataloguing, Analysis and Techniques
Service
Authors: Barnes, D.; Harrison, R. A.; Davies, J. A.; Byrne, J.;
Perry, C. H.; Moestl, C.; Rouillard, A. P.; Bothmer, V.; Rodriguez,
L.; Eastwood, J. P.; Kilpua, E.; Odstrcil, D.; Gallagher, P.
2015AGUFMSH21B2410B Altcode:
Understanding the evolution of the solar wind is fundamental to
advancing our knowledge of energy and mass transport in the Solar
System, making it crucial to space weather and its prediction. The
advent of truly wide-angle heliospheric imaging has revolutionised
the study of both transient (CMEs) and background (IRs) solar wind
plasma structures, by enabling their direct and continuous observation
out to 1 AU and beyond. The EU-funded FP7 HELCATS project combines
European expertise in heliospheric imaging, built up in particular
through lead involvement in NASA's STEREO mission, with expertise in
solar and coronal imaging as well as in-situ and radio measurements
of solar wind phenomena, in a programme of work that will enable
a much wider exploitation and understanding of heliospheric imaging
observations. The HELCATS project endeavors to catalogue transient and
background solar wind structures imaged by STEREO/HI throughout the
duration of the mission. This catalogue will include estimates of their
kinematic properties using a variety of established and more speculative
approaches, which are to be evaluated through comparisons with solar
source and in-situ measurements. The potential for driving numerical
models from these kinematic properties is to be assessed, as is their
complementarity to radio observations, specifically Type II bursts and
interplanetary scintillation. This presentation provides an overview of
the HELCATS project and its progress in first 18 months of operations.

---------------------------------------------------------
Title: Low frequency radio observations of bi-directional electron
beams in the solar corona
Authors: Carley, Eoin P.; Reid, Hamish; Vilmer, Nicole; Gallagher,
Peter T.
2015A&A...581A.100C Altcode: 2015arXiv150801065C
The radio signature of a shock travelling through the solar corona
is known as a type II solar radio burst. In rare cases these bursts
can exhibit a fine structure known as "herringbones", which are a
direct indicator of particle acceleration occurring at the shock
front. However, few studies have been performed on herringbones and
the details of the underlying particle acceleration processes are
unknown. Here, we use an image processing technique known as the Hough
transform to statistically analyse the herringbone fine structure in
a radio burst at ~20-90 MHz observed from the Rosse Solar-Terrestrial
Observatory on 2011 September 22. We identify 188 individual bursts
which are signatures of bi-directional electron beams continuously
accelerated to speeds of 0.16-0.10+0.11
c. This occurs at a shock acceleration site initially at a constant
altitude of ~0.6 R⊙ in the corona, followed by a shift
to ~0.5 R⊙. The anti-sunward beams travel a distance of
170-97+174 Mm (and possibly further) away from the
acceleration site, while those travelling toward the Sun come to a stop
sooner, reaching a smaller distance of 112-76+84
Mm. We show that the stopping distance for the sunward beams may depend
on the total number density and the velocity of the beam. Our study
concludes that a detailed statistical analysis of herringbone fine
structure can provide information on the physical properties of the
corona which lead to these relatively rare radio bursts.

---------------------------------------------------------
Title: LOFAR tied-array imaging and spectroscopy of solar S bursts
Authors: Morosan, D. E.; Gallagher, P. T.; Zucca, P.; O'Flannagain,
A.; Fallows, R.; Reid, H.; Magdalenić, J.; Mann, G.; Bisi, M. M.;
Kerdraon, A.; Konovalenko, A. A.; MacKinnon, A. L.; Rucker, H. O.;
Thidé, B.; Vocks, C.; Alexov, A.; Anderson, J.; Asgekar, A.;
Avruch, I. M.; Bentum, M. J.; Bernardi, G.; Bonafede, A.; Breitling,
F.; Broderick, J. W.; Brouw, W. N.; Butcher, H. R.; Ciardi, B.;
de Geus, E.; Eislöffel, J.; Falcke, H.; Frieswijk, W.; Garrett,
M. A.; Grießmeier, J.; Gunst, A. W.; Hessels, J. W. T.; Hoeft, M.;
Karastergiou, A.; Kondratiev, V. I.; Kuper, G.; van Leeuwen, J.;
McKay-Bukowski, D.; McKean, J. P.; Munk, H.; Orru, E.; Paas, H.;
Pizzo, R.; Polatidis, A. G.; Scaife, A. M. M.; Sluman, J.; Tasse,
C.; Toribio, M. C.; Vermeulen, R.; Zarka, P.
2015A&A...580A..65M Altcode: 2015arXiv150707496M
Context. The Sun is an active source of radio emission that is
often associated with energetic phenomena ranging from nanoflares to
coronal mass ejections (CMEs). At low radio frequencies (&lt;100 MHz),
numerous millisecond duration radio bursts have been reported, such
as radio spikes or solar S bursts (where S stands for short). To date,
these have neither been studied extensively nor imaged because of the
instrumental limitations of previous radio telescopes. Aims:
Here, LOw Frequency ARray (LOFAR) observations were used to study
the spectral and spatial characteristics of a multitude of S bursts,
as well as their origin and possible emission mechanisms. 
Methods: We used 170 simultaneous tied-array beams for spectroscopy
and imaging of S bursts. Since S bursts have short timescales
and fine frequency structures, high cadence (~50 ms) tied-array
images were used instead of standard interferometric imaging, that
is currently limited to one image per second. Results: On 9
July 2013, over 3000 S bursts were observed over a time period of ~8
h. S bursts were found to appear as groups of short-lived (&lt;1 s)
and narrow-bandwidth (~2.5 MHz) features, the majority drifting at
~3.5 MHz s-1 and a wide range of circular polarisation
degrees (2-8 times more polarised than the accompanying Type III
bursts). Extrapolation of the photospheric magnetic field using the
potential field source surface (PFSS) model suggests that S bursts
are associated with a trans-equatorial loop system that connects an
active region in the southern hemisphere to a bipolar region of plage
in the northern hemisphere. Conclusions: We have identified
polarised, short-lived solar radio bursts that have never been imaged
before. They are observed at a height and frequency range where plasma
emission is the dominant emission mechanism, however, they possess
some of the characteristics of electron-cyclotron maser emission. A movie associated to Fig. 3 is available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201526064/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: Ellerman Bombs with Jets: Cause and Effect
Authors: Reid, A.; Mathioudakis, M.; Scullion, E.; Doyle, J. G.;
Shelyag, S.; Gallagher, P.
2015ApJ...805...64R Altcode: 2015arXiv150305359R
Ellerman Bombs (EBs) are thought to arise as a result of photospheric
magnetic reconnection. We use data from the Swedish 1 m Solar
Telescope to study EB events on the solar disk and at the limb. Both
data sets show that EBs are connected to the foot points of forming
chromospheric jets. The limb observations show that a bright structure
in the Hα blue wing connects to the EB initially fueling it, leading
to the ejection of material upwards. The material moves along a loop
structure where a newly formed jet is subsequently observed in the
red wing of Hα. In the disk data set, an EB initiates a jet which
propagates away from the apparent reconnection site within the EB
flame. The EB then splits into two, with associated brightenings in
the inter-granular lanes. Micro-jets are then observed, extending
to 500 km with a lifetime of a few minutes. Observed velocities of
the micro-jets are approximately 5-10 km s-1, while their
chromospheric counterparts range from 50 to 80 km s-1. MURaM
simulations of quiet Sun reconnection show that micro-jets with
properties similar to those of the observations follow the line of
reconnection in the photosphere, with associated Hα brightening at
the location of increased temperature.

---------------------------------------------------------
Title: Solar and Heliospheric Physics with the Square Kilometre Array
Authors: Nakariakov, V.; Bisi, M. M.; Browning, P. K.; Maia,
D.; Kontar, E. P.; Oberoi, D.; Gallagher, P. T.; Cairns, I. H.;
Ratcliffe, H.
2015aska.confE.169N Altcode: 2015PoS...215E.169N; 2015arXiv150700516N
The fields of solar radiophysics and solar system radio physics,
or radio heliophysics, will benefit immensely from an instrument
with the capabilities projected for SKA. Potential applications
include interplanetary scintillation (IPS), radio-burst tracking,
and solar spectral radio imaging with a superior sensitivity. These
will provide breakthrough new insights and results in topics of
fundamental importance, such as the physics of impulsive energy
releases, magnetohydrodynamic oscillations and turbulence, the
dynamics of post-eruptive processes, energetic particle acceleration,
the structure of the solar wind and the development and evolution of
solar wind transients at distances up to and beyond the orbit of the
Earth. The combination of the high spectral, time and spatial resolution
and the unprecedented sensitivity of the SKA will radically advance
our understanding of basic physical processes operating in solar and
heliospheric plasmas and provide a solid foundation for the forecasting
of space weather events.

---------------------------------------------------------
Title: The energetics of a global shock wave in the low solar corona
Authors: Long, David; Baker, Deborah; Williams, David; Carley, Eoin;
Gallagher, Peter; Zucca, Pietro
2015TESS....140706L Altcode:
As the most energetic eruptions in the solar system, coronal mass
ejections (CMEs) can produce shock waves at both their front and flanks
as they erupt from the Sun into the heliosphere. However, the amount of
energy produced in these eruptions, and the proportion of their energy
required to produce the waves, is not well characterised. Here we use
observations of a solar eruption from 2014 February 25 to estimate
the energy budget of an erupting CME and the globally-propagating
"EIT wave" produced by the rapid expansion of the CME flanks in the
low solar corona. The "EIT wave" is shown using a combination of
radio spectra and extreme ultraviolet images to be a shock front
with a Mach number greater than one. Its initial energy is then
calculated using the Sedov-Taylor blast-wave approximation, which
provides an approximation for a shock front propagating through a
region of variable density. This approach provides an initial energy
estimate of ~2.8 x 10^31 ergs to produce the "EIT wave", which is
approximately 10% the kinetic energy of the associated CME (shown to
be ~2.5 x 10^32 ergs). These results indicate that the energy of the
"EIT wave" may be significant and must be considered when estimating
the total energy budget of solar eruptions.

---------------------------------------------------------
Title: Stable umbral chromospheric structures
Authors: Henriques, V. M. J.; Scullion, E.; Mathioudakis, M.; Kiselman,
D.; Gallagher, P. T.; Keenan, F. P.
2015A&A...574A.131H Altcode: 2014arXiv1412.6100H
 Aims: We seek to understand the morphology of the chromosphere in
sunspot umbra. We investigate if the horizontal structures observed
in the spectral core of the Ca II H line are ephemeral visuals
caused by the shock dynamics of more stable structures, and examine
their relationship with observables in the H-alpha line. 
Methods: Filtergrams in the core of the Ca II H and H-alpha lines
as observed with the Swedish 1-m Solar Telescope are employed. We
utilise a technique that creates composite images and tracks the
flash propagation horizontally. Results: We find 0.̋15 wide
horizontal structures, in all of the three target sunspots, for every
flash where the seeing is moderate to good. Discrete dark structures
are identified that are stable for at least two umbral flashes, as well
as systems of structures that live for up to 24 min. We find cases of
extremely extended structures with similar stability, with one such
structure showing an extent of 5”. Some of these structures have a
correspondence in H-alpha, but we were unable to find a one-to-one
correspondence for every occurrence. If the dark streaks are formed at
the same heights as umbral flashes, there are systems of structures
with strong departures from the vertical for all three analysed
sunspots. Conclusions: Long-lived Ca II H filamentary horizontal
structures are a common and likely ever-present feature in the umbra
of sunspots. If the magnetic field in the chromosphere of the umbra
is indeed aligned with the structures, then the present theoretical
understanding of the typical umbra needs to be revisited. Movies
associated to Figs. 3 and 4 are available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201424664/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: The Energetics of a Global Shock Wave in the Low Solar Corona
Authors: Long, David M.; Baker, Deborah; Williams, David R.; Carley,
Eoin P.; Gallagher, Peter T.; Zucca, Pietro
2015ApJ...799..224L Altcode: 2014arXiv1412.2964L
As the most energetic eruptions in the solar system, coronal mass
ejections (CMEs) can produce shock waves at both their front and flanks
as they erupt from the Sun into the heliosphere. However, the amount of
energy produced in these eruptions, and the proportion of their energy
required to produce the waves, is not well characterized. Here we use
observations of a solar eruption from 2014 February 25 to estimate
the energy budget of an erupting CME and the globally propagating
"EIT wave" produced by the rapid expansion of the CME flanks in the
low solar corona. The "EIT wave" is shown using a combination of radio
spectra and extreme ultraviolet images to be a shock front with a
Mach number greater than one. Its initial energy is then calculated
using the Sedov-Taylor blast-wave approximation, which provides an
approximation for a shock front propagating through a region of variable
density. This approach provides an initial energy estimate of ≈2.8 ×
1031 erg to produce the "EIT wave," which is approximately
10% the kinetic energy of the associated CME (shown to be ≈2.5 ×
1032 erg). These results indicate that the energy of the
"EIT wave" may be significant and must be considered when estimating
the total energy budget of solar eruptions.

---------------------------------------------------------
Title: Solar Hard X-Ray Source Sizes in a Beam-heated and Ionized
Chromosphere
Authors: O'Flannagain, Aidan M.; Brown, John C.; Gallagher, Peter T.
2015ApJ...799..127O Altcode:
Solar flare hard X-rays (HXRs) are produced as bremsstrahlung
when an accelerated population of electrons interacts with the
dense chromospheric plasma. HXR observations presented by Kontar et
al. using the Ramaty High-Energy Solar Spectroscopic Imager have shown
that HXR source sizes are three to six times more extended in height
than those predicted by the standard collisional thick target model
(CTTM). Several possible explanations have been put forward including
the multi-threaded nature of flare loops, pitch-angle scattering,
and magnetic mirroring. However, the nonuniform ionization (NUI)
structure along the path of the electron beam has not been fully
explored as a solution to this problem. Ionized plasma is known to
be less effective at producing nonthermal bremsstrahlung HXRs when
compared to neutral plasma. If the peak HXR emission was produced in
a locally ionized region within the chromosphere, the intensity of
emission will be preferentially reduced around this peak, resulting in
a more extended source. Due to this effect, along with the associated
density enhancement in the upper chromosphere, injection of a beam of
electrons into a partially ionized plasma should result in an HXR source
that is substantially more vertically extended relative to that for a
neutral target. Here we present the results of a modification to the
CTTM, which takes into account both a localized form of chromospheric
NUI and an increased target density. We find 50 keV HXR source widths,
with and without the inclusion of a locally ionized region, of ~3 Mm
and ~0.7 Mm, respectively. This helps to provide a theoretical solution
to the currently open question of overly extended HXR sources.

---------------------------------------------------------
Title: Simulating Geomagnetically Induced Currents in the Irish
Power Network
Authors: Jones, A. G.; Blake, S. P.; Gallagher, P.; McCauley, J.;
Hogg, C.; Beggan, C.; Thomson, A. W. P.; Kelly, G.; Walsh, S.
2014AGUFMSM31A4179J Altcode:
Geomagnetic storms are known to cause geomagnetically induced
currents (GICs) which can damage or destroy transformers on power
grids. Previous studies have examined the vulnerability of power
networks in countries such as the UK, New Zealand, Canada and South
Africa. Here we describe the application of a British Geological Survey
(BGS) thin-sheet conductivity model to compute the geo-electric field
from the variation of the magnetic field, in order to better quantify
the risk of space weather to Ireland's power network. This was achieved
using DIAS magnetotelluric data from across Ireland. As part of a
near-real-time warning package for Eirgrid (who oversee Ireland's
transmission network), severe storm events such as the Halloween 2003
storm and the corresponding GIC flows at transformers are simulated.

---------------------------------------------------------
Title: The HELCATS Project: Characterising the Evolution of Coronal
Mass Ejections Observed During Solar Cycle 24
Authors: Bisi, M. M.; Harrison, R. A.; Davies, J. A.; Perry, C. H.;
Moestl, C.; Rouillard, A. P.; Bothmer, V.; Rodriguez, L.; Eastwood,
J. P.; Kilpua, E.; Gallagher, P.; Odstrcil, D.
2014AGUFMSH43B4214B Altcode:
Understanding the evolution of coronal mass ejections (CMEs) is
fundamental to advancing our knowledge of energy and mass transport in
the solar system, thus also rendering it crucial to space weather and
its prediction. The advent of truly wide-angle heliospheric imaging
has revolutionised the study of CMEs, by enabling their direct and
continuous observation as they propagate from the Sun out to 1 AU and
beyond. The recently initiated EU-funded FP7 Heliospheric Cataloguing,
Analysis and Technique Service (HELCATS) project combines European
expertise in the field of heliospheric imaging, built up over the last
decade in particular through lead involvement in NASA's STEREO mission,
with expertise in such areas as solar and coronal imaging as well as
the interpretation of in-situ and radio diagnostic measurements of
solar wind phenomena. The goals of HELCATS include the cataloguing
of CMEs observed in the heliosphere by the Heliospheric Imager
(HI) instruments on the STEREO spacecraft, since their launch in
late October 2006 to date, an interval that covers much of the
historically weak solar cycle 24. Included in the catalogue will be
estimates of the kinematic properties of the imaged CMEs, based on a
variety of established, and some more speculative, modelling approaches
(geometrical, forward, inverse, magneto-hydrodynamic); these kinematic
properties will be verified through comparison with solar disc and
coronal imaging observations, as well as through comparison with radio
diagnostic and in-situ measurements made at multiple points throughout
the heliosphere. We will provide an overview of the HELCATS project,
and present initial results that will seek to illuminate the unusual
nature of solar cycle 24.

---------------------------------------------------------
Title: Solar Hard X-ray Source Sizes in a Beam-Heated and Ionised
Chromosphere
Authors: O'Flannagain, A.; Brown, J. C.; Gallagher, P. T.
2014arXiv1411.5168O Altcode:
Solar flare hard X-rays (HXRs) are produced as bremsstrahlung
when an accelerated population of electrons interacts with the
dense chromospheric plasma. HXR observations presented by using
the Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) have
shown that HXR source sizes are 3-6 times more extended in height
than those predicted by the standard collisional thick target model
(CTTM). Several possible explanations have been put forward including
the multi-threaded nature of flare loops, pitch-angle scattering,
and magnetic mirroring. However, the nonuniform ionisation (NUI)
structure along the path of the electron beam has not been fully
explored as a solution to this problem. Ionised plasma is known to
be less effective at producing nonthermal bremsstrahlung HXRs when
compared to neutral plasma. If the peak HXR emission was produced in
a locally ionised region within the chromosphere, the intensity of
emission will be preferentially reduced around this peak, resulting in
a more extended source. Due to this effect, along with the associated
density enhancement in the upper chromosphere, injection of a beam of
electrons into a partially ionised plasma should result in a HXR source
which is substantially more vertically extended relative to that for a
neutral target. Here we present the results of a modification to the
CTTM which takes into account both a localised form of chromospheric
NUI and an increased target density. We find 50 keV HXR source widths,
with and without the inclusion of a locally ionised region, of ~3 Mm
and ~0.7 Mm, respectively. This helps to provide a theoretical solution
to the currently open question of overly-extended HXR sources.

---------------------------------------------------------
Title: Understanding Coronal Mass Ejections and Associated Shocks
in the Solar Corona by Merging Multiwavelength Observations
Authors: Zucca, P.; Pick, M.; Démoulin, P.; Kerdraon, A.; Lecacheux,
A.; Gallagher, P. T.
2014ApJ...795...68Z Altcode: 2014arXiv1409.3691Z
Using multiwavelength imaging observations, in EUV, white light
and radio, and radio spectral data over a large frequency range,
we analyzed the triggering and development of a complex eruptive
event. This one includes two components, an eruptive jet and a coronal
mass ejection (CME), which interact during more than 30 minutes, and
can be considered as physically linked. This was an unusual event. The
jet is generated above a typical complex magnetic configuration that
has been investigated in many former studies related to the build-up of
eruptive jets; this configuration includes fan-field lines originating
from a corona null point above a parasitic polarity, which is embedded
in one polarity region of a large active region. The initiation and
development of the CME, observed first in EUV, does not show usual
signatures. In this case, the eruptive jet is the main actor of this
event. The CME appears first as a simple loop system that becomes
destabilized by magnetic reconnection between the outer part of the jet
and the ambient medium. The progression of the CME is closely associated
with the occurrence of two successive type II bursts from a distinct
origin. An important part of this study is the first radio type II burst
for which the joint spectral and imaging observations were allowed:
(1) to follow, step by step, the evolution of the spectrum and of the
trajectory of the radio burst, in relationship with the CME evolution
and (2) to obtain, without introducing an electronic density model,
the B field and the Alfvén speed.

---------------------------------------------------------
Title: CorPITA: An Automated Algorithm for the Identification and
Analysis of Coronal "EIT Waves"
Authors: Long, D. M.; Bloomfield, D. S.; Gallagher, P. T.;
Pérez-Suárez, D.
2014SoPh..289.3279L Altcode: 2014arXiv1403.6722L; 2014SoPh..tmp...66L
The continuous stream of data available from the Atmospheric Imaging
Assembly (AIA) telescopes onboard the Solar Dynamics Observatory (SDO)
spacecraft has allowed a deeper understanding of the Sun. However,
the sheer volume of data has necessitated the development of automated
techniques to identify and analyse various phenomena. In this article,
we describe the Coronal Pulse Identification and Tracking Algorithm
(CorPITA) for the identification and analysis of coronal "EIT
waves". CorPITA uses an intensity-profile technique to identify the
propagating pulse, tracking it throughout its evolution before returning
estimates of its kinematics. The algorithm is applied here to a data
set from February 2011, allowing its capabilities to be examined and
critiqued. This algorithm forms part of the SDO Feature Finding Team
initiative and will be implemented as part of the Heliophysics Event
Knowledgebase (HEK). This is the first fully automated algorithm
to identify and track the propagating "EIT wave" rather than any
associated phenomenon and will allow a deeper understanding of this
controversial phenomenon.

---------------------------------------------------------
Title: LOFAR tied-array imaging of Type III solar radio bursts
Authors: Morosan, D. E.; Gallagher, P. T.; Zucca, P.; Fallows, R.;
Carley, E. P.; Mann, G.; Bisi, M. M.; Kerdraon, A.; Konovalenko, A. A.;
MacKinnon, A. L.; Rucker, H. O.; Thidé, B.; Magdalenić, J.; Vocks,
C.; Reid, H.; Anderson, J.; Asgekar, A.; Avruch, I. M.; Bentum, M. J.;
Bernardi, G.; Best, P.; Bonafede, A.; Bregman, J.; Breitling, F.;
Broderick, J.; Brüggen, M.; Butcher, H. R.; Ciardi, B.; Conway, J. E.;
de Gasperin, F.; de Geus, E.; Deller, A.; Duscha, S.; Eislöffel, J.;
Engels, D.; Falcke, H.; Ferrari, C.; Frieswijk, W.; Garrett, M. A.;
Grießmeier, J.; Gunst, A. W.; Hassall, T. E.; Hessels, J. W. T.;
Hoeft, M.; Hörandel, J.; Horneffer, A.; Iacobelli, M.; Juette, E.;
Karastergiou, A.; Kondratiev, V. I.; Kramer, M.; Kuniyoshi, M.; Kuper,
G.; Maat, P.; Markoff, S.; McKean, J. P.; Mulcahy, D. D.; Munk, H.;
Nelles, A.; Norden, M. J.; Orru, E.; Paas, H.; Pandey-Pommier, M.;
Pandey, V. N.; Pietka, G.; Pizzo, R.; Polatidis, A. G.; Reich, W.;
Röttgering, H.; Scaife, A. M. M.; Schwarz, D.; Serylak, M.; Smirnov,
O.; Stappers, B. W.; Stewart, A.; Tagger, M.; Tang, Y.; Tasse, C.;
Thoudam, S.; Toribio, C.; Vermeulen, R.; van Weeren, R. J.; Wucknitz,
O.; Yatawatta, S.; Zarka, P.
2014A&A...568A..67M Altcode: 2014arXiv1407.4385M
Context. The Sun is an active source of radio emission which is often
associated with energetic phenomena such as solar flares and coronal
mass ejections (CMEs). At low radio frequencies (&lt;100 MHz), the Sun
has not been imaged extensively because of the instrumental limitations
of previous radio telescopes. Aims: Here, the combined high
spatial, spectral, and temporal resolution of the LOw Frequency ARray
(LOFAR) was used to study solar Type III radio bursts at 30-90 MHz and
their association with CMEs. Methods: The Sun was imaged with
126 simultaneous tied-array beams within ≤5 R⊙ of the
solar centre. This method offers benefits over standard interferometric
imaging since each beam produces high temporal (~83 ms) and spectral
resolution (12.5 kHz) dynamic spectra at an array of spatial locations
centred on the Sun. LOFAR's standard interferometric output is currently
limited to one image per second. Results: Over a period of 30
min, multiple Type III radio bursts were observed, a number of which
were found to be located at high altitudes (~4 R⊙ from
the solar center at 30 MHz) and to have non-radial trajectories. These
bursts occurred at altitudes in excess of values predicted by 1D radial
electron density models. The non-radial high altitude Type III bursts
were found to be associated with the expanding flank of a CME. Conclusions: The CME may have compressed neighbouring streamer
plasma producing larger electron densities at high altitudes, while
the non-radial burst trajectories can be explained by the deflection
of radial magnetic fields as the CME expanded in the low corona. Movie associated to Fig. 2 is available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201423936/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: The Compatibility of Flare Temperatures Observed with AIA,
GOES, and RHESSI
Authors: Ryan, Daniel F.; O'Flannagain, Aidan M.; Aschwanden, Markus
J.; Gallagher, Peter T.
2014SoPh..289.2547R Altcode: 2014SoPh..tmp...31R; 2014arXiv1401.4098R
We test the compatibility and biases of multi-thermal flare DEM
(differential emission measure) peak temperatures determined with
AIA with those determined by GOES and RHESSI using the isothermal
assumption. In a set of 149 M- and X-class flares observed
during the first two years of the SDO mission, AIA finds DEM peak
temperatures at the time of the peak GOES 1 - 8 Å flux to have
an average of Tp=12.0±2.9 MK and Gaussian DEM widths of
log10(σT)=0.50±0.13. From GOES observations of
the same 149 events, a mean temperature of Tp=15.6±2.4
MK is inferred, which is systematically higher by a factor of
TGOES/TAIA=1.4±0.4. We demonstrate that
this discrepancy results from the isothermal assumption in the
inversion of the GOES filter ratio. From isothermal fits to photon
spectra at energies of ϵ≈6 - 12 keV of 61 of these events,
RHESSI finds the temperature to be higher still by a factor of
TRHESSI/TAIA=1.9±1.0. We find that this is
partly a consequence of the isothermal assumption. However, RHESSI
is not sensitive to the low-temperature range of the DEM peak,
and thus RHESSI samples only the high-temperature tail of the DEM
function. This can also contribute to the discrepancy between AIA and
RHESSI temperatures. The higher flare temperatures found by GOES and
RHESSI imply correspondingly lower emission measures. We conclude that
self-consistent flare DEM temperatures and emission measures require
simultaneous fitting of EUV (AIA) and soft X-ray (GOES and RHESSI)
fluxes.

---------------------------------------------------------
Title: a Workflow-Oriented Approach to Propagation Models in
Heliophysics
Authors: Pierantoni, Gabriele; Carley, Eoin P.; Byrne, Jason P.;
Perez-Suarez, David; Gallagher, Peter T.
2014ComSc..15..271P Altcode:
The Sun is responsible for the eruption of billions of tons of plasma
andthe generation of near light-speed particles that propagate
throughout the solarsystem and beyond. If directed towards Earth,
these events can be damaging toour tecnological infrastructure. Hence
there is an effort to understand the causeof the eruptive events
and how they propagate from Sun to Earth. However, thephysics
governing their propagation is not well understood, so there is a need
todevelop a theoretical description of their propagation, known as a
PropagationModel, in order to predict when they may impact Earth. It
is often difficultto define a single propagation model that correctly
describes the physics ofsolar eruptive events, and even more difficult
to implement models capable ofcatering for all these complexities and
to validate them using real observational data. In this paper, we
envisage that workflows offer both a theoretical andpractical framerwork
for a novel approach to propagation models. We definea mathematical
framework that aims at encompassing the different modalitieswith
which workflows can be used, and provide a set of generic building
blockswritten in the TAVERNA workflow language that users can use to
build theirown propagation models. Finally we test both the theoretical
model and thecomposite building blocks of the workflow with a real
Science Use Case that wasdiscussed during the 4th CDAW (Coordinated
Data Analysis Workshop) eventheld by the HELIO project. We show that
generic workflow building blocks canbe used to construct a propagation
model that succesfully describes the transitof solar eruptive events
toward Earth and predict a correct Earth-impact time

---------------------------------------------------------
Title: A study of sympathetic eruptions using the Heliophysics
Events Knowledgebase
Authors: Higgins, Paul A.; Schrijver, Carolus J.; Title, Alan M.;
Bloomfield, D. Shaun; Gallagher, Peter T
2014AAS...22412316H Altcode:
Over the past few decades there have been a number of papers
investigating the connection between flares occurring in
succession. Statistically, any connection that affects the timing of
successive flares that exists is found to be weak. However, the majority
of previous investigations has been limited by only considering the
causal connection between soft X-ray flares. More recent case studies
have shown convincing evidence that large eruptions cause a global
reorganization of overlying magnetic fields that can result in the
eruption of both flares and filaments at large distances from the
original event. In this work, the connection between GOES X-ray flares
(C-, M-, and X-class) and filament eruptions occurring in succession in
two different active regions is considered statistically. The filament
eruptions are recorded in the Heliophysics Events Knowledgebase
by observers using SDO/AIA data. A significant causal connection is
found between the two event types, such that large flares are followed
by filament eruptions within 24 hours much more often than they are
preceded by filament eruptions. This stipulates that the flares either
cause the filaments to erupt or affect the eruption timing such that
the filament eruptions follow the flares more closely in time.

---------------------------------------------------------
Title: The Compatibility of Flare Temperatures Observed with AIA,
GOES, and RHESSI
Authors: Ryan, Daniel; Aschwanden, Markus J.; O'Flannagain, Aidan M;
Gallagher, Peter T
2014AAS...22412337R Altcode:
In this talk we compare multi-thermal flare DEM peak temperatures
determined with SDO/AIA with those determined by GOES/XRS and RHESSI
using the isothermal assumption. In a set of 149 M- and X-class flares,
AIA finds an average DEM peak temperature at the time of the GOES long
channel peak of 12.0±2.9 MK and Gaussian DEM widths of log10(σT )
= 0.50±0.13. From GOES observations of the same 149 events, a mean
temperature of 15.6±2.4 MK is inferred, which is higher by a factor
of TGOES/TAIA = 1.4±0.4. We demonstrate that this discrepancy results
from the isothermal assumption in the inversion of the GOES filter
ratio. From isothermal fits to photon spectra at energies of 6-12
keV of 61 of these events, RHESSI finds the temperature to be higher
(TRHESSI/TAIA = 1.9±1.0). We find that this is partly a consequence
of the isothermal assumption. However, RHESSI is not sensitive to
the low-temperature range of the DEM peak, and thus only samples the
DEM’s high-temperature tail. This is expected to be the cause of
further discrepancies. We conclude that self-consistent flare DEM
temperatures require simultaneous fitting of EUV and SXR fluxes.

---------------------------------------------------------
Title: Sunspotter: Using Citizen Science to Determine the Complexity
of Sunspots
Authors: Higgins, Paul A.; Perez-Suarez, David; Parrish, Michael;
O'Callaghan, David; Leka, K D.; Barnes, Graham; Roche, Joseph;
Gallagher, Peter T
2014AAS...22411203H Altcode:
It is well known that sunspot groups with large, complex magnetic field
configurations and strong, sheared polarity separation lines produce
the largest flares. While methods for determining certain physical
properties, such as total magnetic flux and polarity-separation-line
length have been successfully developed for characterizing sunspot
groups, a reliable automated method for determining sunspot
complexity has never been developed. Since complexity can only be
measured in a relative sense, we have used crowd-sourcing methods
to allow human observers to compare the complexity of pairs of
sunspot groups. This allows a large dataset to be ranked in terms of
complexity. Sunspotter.org uses the Zooniverse platform and allows
the general public to contribute comparisons using a web-browser
interface. The results of this project will help to establish the true
relationship between sunspot group complexity and flares, which has
been discussed in the solar physics community for many decades.

---------------------------------------------------------
Title: Decay-phase Cooling and Inferred Heating of M- and X-class
Solar Flares
Authors: Ryan, Daniel; Chamberlin, Phillip C.; Milligan, Ryan O.;
Gallagher, Peter T
2014AAS...22412315R Altcode:
Hydrodynamic modelling is a well established and important field in
understanding the evolution of solar flares. However, in order to
be of greatest use the results of such models must be compared to
statistically significant samples of flare observations. In this talk
we observationally investigate the hydrodynamic decay phase evolution
of 72 M- and X-class flares using GOES/XRS, SDO/EVE and Hinode/XRT
and quantify their cooling rates. The results are then compared
to the predictions of an analytical zero-dimensional hydrodynamic
model. We find that the model does not fit the observations well,
but does provide a well-defined lower limit on a flare's total cooling
time. The discrepancy between observations and the model is then assumed
to be primarily due to heating during the decay phase. The decay-phase
heating necessary to account for the discrepancy is quantified and
found be ~50% of the total thermally radiated energy, as calculated
with GOES/XRS. This suggests that the energy released during the decay
phase may be as significant as that released during the rise phase.

---------------------------------------------------------
Title: The formation heights of coronal shocks from 2D density and
Alfvén speed maps
Authors: Zucca, Pietro; Carley, Eoin P.; Bloomfield, D. Shaun;
Gallagher, Peter T.
2014A&A...564A..47Z Altcode: 2014arXiv1402.4051Z
Context. Super-Alfvénic shocks associated with coronal mass ejections
(CMEs) can produce radio emission known as Type II bursts. In the
absence of direct imaging, accurate estimates of coronal electron
densities, magnetic field strengths, and Alfvén speeds are required
to calculate the kinematics of shocks. To date, 1D radial models have
been used, but these are not appropriate for shocks propagating in
non-radial directions. Aims: Here, we study a coronal shock
wave associated with a CME and Type II radio burst using 2D electron
density and Alfvén speed maps to determine the locations that shocks
are excited as the CME expands through the corona. Methods:
Coronal density maps were obtained from emission measures derived
from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic
Observatory (SDO) and polarized brightness measurements from the Large
Angle and Spectrometric Coronagraph (LASCO) on board the Solar and
Heliospheric Observatory (SOHO). Alfvén speed maps were calculated
using these density maps and magnetic field extrapolations from the
Helioseismic and Magnetic Imager (SDO/HMI). The computed density and
Alfvén speed maps were then used to calculate the shock kinematics in
non-radial directions. Results: Using the kinematics of the Type
II burst and associated shock, we find our observations to be consistent
with the formation of a shock located at the CME flanks where the
Alfvén speed has a local minimum. Conclusions: The 1D density
models are not appropriate for shocks that propagate non-radially along
the flanks of a CME. Rather, the 2D density, magnetic field and Alfvén
speed maps described here give a more accurate method for determining
the fundamental properties of shocks and their relation to CMEs.

---------------------------------------------------------
Title: Automated Detection, Characterisation and Tracking of Solar
Coronal Mass Ejections
Authors: Gallagher, Peter; Carley, Eoin; Byrne, Jason; Morgan, Huw;
Refojo, Jose
2014cosp...40E.923G Altcode:
Coronal mass ejections (CMEs) are large eruptions of plasma and
magnetic flux from the Sun through interplanetary space. If they
impact the Earth, they can cause space weather effects that are
detrimental to technological systems upon which society is highly
dependent. It is therefore important to automatically identify and
track CMEs in near-realtime in order to better forecast their possible
arrival at Earth. Due to the diffuse nature and comparatively high
speeds of CMEs, it is computationally challenging to automatically
identify, characterise and track them as they move through the solar
corona and inner heliosphere. Here, we review and discuss current
state-of-the-art image processing techniques, and how they are
being used to automatically generate catalogues of CME properties in
near-realtime and for space weather purposes. Furthermore, we discus
recent advances in the reconstruction and visualisation of CMEs in 3D,
which is crucial to our understanding of their detailed structure and
resulting evolution through space.

---------------------------------------------------------
Title: The Relationship between Coronal Mass Ejections and Low
Frequency Radio Bursts in the Low Corona
Authors: Gallagher, Peter; Carley, Eoin; Byrne, Jason; Long, David;
Zucca, Pietro; Bloomfield, Shaun; McCauley, Joseph
2014cosp...40E.924G Altcode:
Cosmic rays and solar energetic particles may be accelerated to
relativistic energies by shock waves in astrophysical plasmas. On
the Sun, shocks and particle acceleration are often associated with
the eruption of coronal mass ejections (CMEs). However, the physical
relationship between CMEs and shock particle acceleration is not well
understood. Here, we use extreme ultraviolet, radio and white-light
imaging of a solar eruptive event on 22 September 2011 to show that
a CME-induced shock was coincident with a coronal wave and an intense
metric radio burst generated by intermittent acceleration of electrons
to kinetic energies of 2-46 keV (0.1-0.4 c). Our observations show that
plasmoid-driven quasiperpendicular shocks are capable of producing
quasiperiodic acceleration of electrons, an effect consistent with a
turbulent or rippled plasma shock surface.

---------------------------------------------------------
Title: Quasiperiodic acceleration of electrons by a plasmoid-driven
shock in the solar atmosphere
Authors: Carley, Eoin P.; Long, David M.; Byrne, Jason P.; Zucca,
Pietro; Bloomfield, D. Shaun; McCauley, Joseph; Gallagher, Peter T.
2013NatPh...9..811C Altcode: 2014arXiv1406.0743C
Cosmic rays and solar energetic particles may be accelerated to
relativistic energies by shock waves in astrophysical plasmas. On
the Sun, shocks and particle acceleration are often associated with
the eruption of magnetized plasmoids, called coronal mass ejections
(CMEs). However, the physical relationship between CMEs and shock
particle acceleration is not well understood. Here, we use extreme
ultraviolet, radio and white-light imaging of a solar eruptive event
on 22 September 2011 to show that a CME-induced shock (Alfvén Mach
number ) was coincident with a coronal wave and an intense metric
radio burst generated by intermittent acceleration of electrons to
kinetic energies of 2-46keV (0.1-0.4c). Our observations show that
plasmoid-driven quasiperpendicular shocks are capable of producing
quasiperiodic acceleration of electrons, an effect consistent with a
turbulent or rippled plasma shock surface.

---------------------------------------------------------
Title: Decay-phase Cooling and Inferred Heating of M- and X-class
Solar Flares
Authors: Ryan, Daniel F.; Chamberlin, Phillip C.; Milligan, Ryan O.;
Gallagher, Peter T.
2013ApJ...778...68R Altcode: 2014arXiv1401.4079R
In this paper, the cooling of 72 M- and X-class flares is examined using
GOES/XRS and SDO/EVE. The observed cooling rates are quantified and the
observed total cooling times are compared with the predictions of an
analytical zero-dimensional hydrodynamic model. We find that the model
does not fit the observations well, but does provide a well-defined
lower limit on a flare's total cooling time. The discrepancy between
observations and the model is then assumed to be primarily due to
heating during the decay phase. The decay-phase heating necessary to
account for the discrepancy is quantified and found be ~50% of the total
thermally radiated energy, as calculated with GOES. This decay-phase
heating is found to scale with the observed peak thermal energy. It is
predicted that approximating the total thermal energy from the peak is
minimally affected by the decay-phase heating in small flares. However,
in the most energetic flares the decay-phase heating inferred from
the model can be several times greater than the peak thermal energy.

---------------------------------------------------------
Title: Improved methods for determining the kinematics of coronal
mass ejections and coronal waves
Authors: Byrne, J. P.; Long, D. M.; Gallagher, P. T.; Bloomfield,
D. S.; Maloney, S. A.; McAteer, R. T. J.; Morgan, H.; Habbal, S. R.
2013A&A...557A..96B Altcode: 2013arXiv1307.8155B
Context. The study of solar eruptive events and associated phenomena is
of great importance in the context of solar and heliophysics. Coronal
mass ejections (CMEs) and coronal waves are energetic manifestations of
the restructuring of the solar magnetic field and mass motion of the
plasma. Characterising this motion is vital for deriving the dynamics
of these events and thus understanding the physics driving their
initiation and propagation. The development and use of appropriate
methods for measuring event kinematics is therefore imperative. Aims: Traditional approaches to the study of CME and coronal wave
kinematics do not return wholly accurate nor robust estimates of the
true event kinematics and associated uncertainties. We highlight the
drawbacks of these approaches, and demonstrate improved methods for
accurate and reliable determination of the kinematics. Methods:
The Savitzky-Golay filter is demonstrated as a more appropriate fitting
technique for CME and coronal wave studies, and a residual resampling
bootstrap technique is demonstrated as a statistically rigorous method
for the determination of kinematic error estimates and goodness-of-fit
tests. Results: It is shown that the scatter on distance-time
measurements of small sample size can significantly limit the ability
to derive accurate and reliable kinematics. This may be overcome by
(i) increasing measurement precision and sampling cadence; and (ii)
applying robust methods for deriving the kinematics and reliably
determining their associated uncertainties. If a priori knowledge
exists and a pre-determined model form for the kinematics is available
(or indeed any justified fitting-form to be tested against the data),
then its precision can be examined using a bootstrapping technique to
determine the confidence interval associated with the model/fitting
parameters. Conclusions: Improved methods for determining the
kinematics of CMEs and coronal waves are demonstrated to great effect,
overcoming many issues highlighted in traditional numerical differencing
and error propagation techniques.

---------------------------------------------------------
Title: HELIO - Discovering solar effects in all the heliosphere
Authors: Pérez-Suárez, D.; Bentley, R. D.; Aboudarham, J.; Brooke,
J.; Csillaghy, A.; Gallagher, P. T.; Jacquey, C.; Messerotti, M.;
Pierantoni, G.
2013EPSC....8..328P Altcode:
HELIO, the HELiophysics Integrated Observatory, consists of a set of
integrated software tools developed by an international consortium under
the European Commission's Seventh Framework Programme (FP7). HELIO
is designed to help scientists easily search heliophysical data
and discover any possible connections. This is achieved by merging
information from feature and event catalogues and services that know
about the locations and capabilities of instruments to find all the data
available that contain information on a certain event by propagating
it through the whole solar system. There are then tools to access data
archives and processing tools that allow the users to create their own
workflows. HELIO is definitely making the research in heliophysics
more accessible to different scientists [1] but it capabilities goes
further than this. It can be adapted to other fields in science,
where multiple observations in different observatories are used to
study a particular event. The interfaces of the HELIO services are
based onWeb services and, as far as possible, are compliant with IVOA
standards. This simplifies access to the capabilities via different
tools like Web browsers, scripting languages (IDL, Python, etc.), and
workflow tools (Taverna, Kepler, etc.). The overall capabilities of
the system can greatly increased when the services are combined using
workflows or scripting languages. While we try to hide the use of these
tools for most users, those who choose to gain familiarity with such
tools can address more complex problems. A brief introduction to
HELIO services and a use case demonstration will be presented.

---------------------------------------------------------
Title: The SWAP EUV Imaging Telescope Part I: Instrument Overview
and Pre-Flight Testing
Authors: Seaton, D. B.; Berghmans, D.; Nicula, B.; Halain, J. -P.; De
Groof, A.; Thibert, T.; Bloomfield, D. S.; Raftery, C. L.; Gallagher,
P. T.; Auchère, F.; Defise, J. -M.; D'Huys, E.; Lecat, J. -H.; Mazy,
E.; Rochus, P.; Rossi, L.; Schühle, U.; Slemzin, V.; Yalim, M. S.;
Zender, J.
2013SoPh..286...43S Altcode: 2012SoPh..tmp..217S; 2012arXiv1208.4631S
The Sun Watcher with Active Pixels and Image Processing (SWAP) is
an EUV solar telescope onboard ESA's Project for Onboard Autonomy 2
(PROBA2) mission launched on 2 November 2009. SWAP has a spectral
bandpass centered on 17.4 nm and provides images of the low solar
corona over a 54×54 arcmin field-of-view with 3.2 arcsec pixels and
an imaging cadence of about two minutes. SWAP is designed to monitor
all space-weather-relevant events and features in the low solar
corona. Given the limited resources of the PROBA2 microsatellite,
the SWAP telescope is designed with various innovative technologies,
including an off-axis optical design and a CMOS-APS detector. This
article provides reference documentation for users of the SWAP image
data.

---------------------------------------------------------
Title: The Projects for Onboard Autonomy (PROBA2) Science Centre:
Sun Watcher Using APS Detectors and Image Processing (SWAP) and
Large-Yield Radiometer (LYRA) Science Operations and Data Products
Authors: Zender, J.; Berghmans, D.; Bloomfield, D. S.; Cabanas Parada,
C.; Dammasch, I.; De Groof, A.; D'Huys, E.; Dominique, M.; Gallagher,
P.; Giordanengo, B.; Higgins, P. A.; Hochedez, J. -F.; Yalim, M. S.;
Nicula, B.; Pylyser, E.; Sanchez-Duarte, L.; Schwehm, G.; Seaton,
D. B.; Stanger, A.; Stegen, K.; Willems, S.
2013SoPh..286...93Z Altcode: 2012SoPh..tmp..142Z
The PROBA2 Science Centre (P2SC) is a small-scale science operations
centre supporting the Sun observation instruments onboard PROBA2:
the EUV imager Sun Watcher using APS detectors and image Processing
(SWAP) and Large-Yield Radiometer (LYRA). PROBA2 is one of ESA's
small, low-cost Projects for Onboard Autonomy (PROBA) and part of
ESA's In-Orbit Technology Demonstration Programme. The P2SC is hosted
at the Royal Observatory of Belgium, co-located with both Principal
Investigator teams. The P2SC tasks cover science planning, instrument
commanding, instrument monitoring, data processing, support of outreach
activities, and distribution of science data products. PROBA missions
aim for a high degree of autonomy at mission and system level, including
the science operations centre. The autonomy and flexibility of the P2SC
is reached by a set of web-based interfaces allowing the operators as
well as the instrument teams to monitor quasi-continuously the status of
the operations, allowing a quick reaction to solar events. In addition,
several new concepts are implemented at instrument, spacecraft, and
ground-segment levels allowing a high degree of flexibility in the
operations of the instruments. This article explains the key concepts
of the P2SC, emphasising the automation and the flexibility achieved
in the commanding as well as the data-processing chain.

---------------------------------------------------------
Title: Temperature Response of the 171 Å Passband of the SWAP Imager
on PROBA2, with a Comparison to TRACE, SOHO, STEREO, and SDO
Authors: Raftery, Claire L.; Bloomfield, D. Shaun; Gallagher, Peter
T.; Seaton, Daniel B.; Berghmans, David; De Groof, Anik
2013SoPh..286..111R Altcode:
We calculated the temperature response of the 171 Å passbands of
the Sun Watcher using APS detectors and image Processing (SWAP)
instrument onboard the PRoject for OnBoard Autonomy 2 (PROBA2)
satellite. These results were compared to the temperature responses
of the Extreme Ultraviolet Imaging Telescope (EIT) onboard the Solar
and Heliospheric Observatory (SOHO), the Transition Region and Coronal
Explorer (TRACE), the twin Extreme Ultraviolet Imagers (EUVI) onboard
the Solar TErrestrial RElations Observatory (STEREO) A and B spacecraft,
and the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics
Observatory (SDO). Multiplying the wavelength-response functions
for each instrument by a series of isothermal synthetic spectra and
integrating over the range 165 - 195 Å produced temperature-response
functions for the six instruments. Each temperature response was
then multiplied by sample differential emission-measure functions
for four different solar conditions. For any given plasma condition
(e.g. quiet Sun, active region), it was found that the overall variation
with temperature agreed remarkably well across the six instruments,
although the wavelength responses for each instrument have some
distinctly different features. Deviations were observed, however,
when we compared the response of any one instrument to different solar
conditions, particularly for the case of solar flares.

---------------------------------------------------------
Title: Solar flare X-ray source motion as a response to electron
spectral hardening
Authors: O'Flannagain, A. M.; Gallagher, P. T.; Brown, J. C.; Milligan,
R. O.; Holman, G. D.
2013A&A...555A..21O Altcode: 2013arXiv1305.1574O
Context. Solar flare hard X-rays (HXRs) are thought to be produced by
nonthermal coronal electrons stopping in the chromosphere or remaining
trapped in the corona. The collisional thick target model (CTTM)
predicts that more energetic electrons penetrate to greater column
depths along the flare loop. This requires that sources produced by
harder power-law injection spectra should appear further down the
legs or footpoints of a flareloop. Therefore, the frequently observed
hardening of the injected power-law electron spectrum during flare
onset should be concurrent with a descending hard X-ray source. 
Aims: We test this implication of the CTTM by comparing its predicted
HXR source locations with those derived from observations of a solar
flare which exhibits a nonthermally-dominated spectrum before the peak
in HXRs, known as an early impulsive event. Methods: The HXR
images and spectra of an early impulsive C-class flare were obtained
using the Ramaty High-Energy Solar Spectroscopic Imager (RHESSI). Images
were reconstructed to produce HXR source height evolutions for three
energy bands. Spatially integrated spectral analysis was performed to
isolate nonthermal emission and to determine the power-law index of the
electron injection spectrum. The observed height-time evolutions were
then fitted with CTTM-based simulated heights for each energy, using
the electron spectral indices derived from the RHESSI spectra. 
Results: The flare emission was found to be dominantly nonthermal
above ~7 keV, with emission of thermal and nonthermal X-rays likely
to be simultaneously observable below that energy. The density
structure required for a good match between model and observed source
heights agreed with previous studies of flare loop densities. 
Conclusions: The CTTM has been used to produce a descent of model HXR
source heights that compares well with observations of this event. Based
on this interpretation, downward motion of nonthermal sources should
occur in any flare where there is spectral hardening in the electron
distribution during a flare. However, this is often masked by thermal
emission associated with flare plasma preheating. To date, flare models
that predict transfer of energy from the corona to the chromosphere by
means other than a flux of nonthermal electrons do not predict this
observed source descent. Therefore, flares such as this will be key
in explaining this elusive energy transfer process.

---------------------------------------------------------
Title: SHILLELAgh: A data-driven solar wind model for studying solar
energetic particle events
Authors: Higgins, Paul Anthony; Perez-Suarez, David; Nitta, Nariaki;
Gallagher, Peter T.
2013shin.confE.140H Altcode:
A method for estimating the properties of the solar wind in the
equatorial plane is presented. OMNI and STEREO in situ solar wind data
is used as input. The solar wind is assumed to propagate radially at
a constant velocity and the corona is assumed to remain static. An
empirical density model is applied to the ballistically propagated
solar wind. A 2D map of solar wind properties is obtained that is
well suited for use in investigations of heliospheric features (e.g.,
co-rotating interaction regions). In this work, the propagation of solar
energetic particle (SEP) events is investigated using the model. Our
method provides a convenient vehicle for assessing the directionality
and hence, the geo-effectiveness of SEP events.

---------------------------------------------------------
Title: Measuring the Diffusion of Solar Magnetic Flux on Large
Spatio-Temporal Scales
Authors: Higgins, Paul Anthony; Bloomfield, D. Shaun; Gallagher,
Peter T.
2013shin.confE..91H Altcode:
We present an investigation of the large-scale flows that influence
magnetic fields at the solar surface. The aim of this work is to
accurately characterise the supergranular diffusion coefficient,
D, that governs the dispersal rate of magnetic features in the
photosphere. There is a disconnect between the measured rate of magnetic
field dispersal ( 50 - 300 km2/s) and the value of D used in global
simulations of solar magnetic field evolution ( 500 - 600 km2/s). We
track the poleward motion of magnetic features in a latitude-time map
and compare the poleward progression to a data-driven simulation that
includes differential rotation, the meridional flow, and supergranular
diffusion. We find that over a time scale of months, setting D = 100
km2/s matches observations, but over a time scale of years, setting D =
500 km2/s is a better match. This supports the idea that observational
time scale causes the disconnect in D values, which leads us to the
conclusion that the present magnetic surface flux transport model is
not adequate to explain the observed evolution of the solar surface
magnetic field.

---------------------------------------------------------
Title: Advanced Techniques for Studying Coronal Mass Ejections in
Three-Dimensions
Authors: Byrne, Jason P.; Morgan, Huw; Habbal, Shadia; Gallagher, Peter
2013shin.confE.161B Altcode:
As the STEREO mission progresses into 2013, the spacecrafts have moved
into quadrature on the far side of the Sun - a unique perspective in the
context of solar physics. This year also heralds the arrival of solar
maximum, when the solar activity cycle should peak and a multitude
of eruptive events may be observed. Therefore, methods for studying
the dynamical evolution of such phenomena as coronal mass ejections
(CMEs) are crucial for revealing the physics at play in these unique
observations. To this end, we present advanced image processing and
stereoscopic techniques for studying CMEs in an effort to determine
their true 3D nature as they propagate through the solar corona. This
is achieved by first performing a dynamic/quiescent signal separation
to remove the static corona in SECCHI images and applying multiscale
filtering techniques to enhance the observed structures. Then an
elliptical tie-pointing technique is used to generate a 3D surface
characterisation of the observed CME front, in order to reveal its true
morphology as it evolves. A model flux-rope was generated in order to
prove the optimal use of this 3D reconstruction technique, especially
while the spacecraft are in quadrature; and is being used to determine
the uncertainties involved in kinematic and morphological analyses of
candidate events observed during this phase of the STEREO mission.

---------------------------------------------------------
Title: SHEBA - HELIO's propagation model: a walk through its
possibilities
Authors: Pérez-Suárez, David; Pierantoni, Gabriele; Maloney, Shane
A.; Higgins, Paul A.; Gallagher, Peter T.; Bentley, Robert D.
2013EGUGA..1513919P Altcode:
The Heliophysics Integrated Observatory (HELIO) is a software
infrastructure involving a collection of web services, heliospheric data
sources (e.g., solar, planetary, etc.), and event catalogues - all of
which are accessible through a unified front end. HELIO brings to the
scientist the possibility to search an event occurred in the heliosphere
and find out which other events are linked with the one under study. To
get the relation between events HELIO uses SHEBA (Solar-Heliospheric
Event Ballistic Algorithm), a simple propagation model for Coronal
Mass Ejections, Solar Energetic Particle and Co-rotating Interaction
Regions. This poster explains the basics of SHEBA and it walks through
real-case scenarios of its use.

---------------------------------------------------------
Title: Observational Calculation of Flare Filling Factors Using
GOES/XRS, SDO/EVE and SDO/AIA
Authors: Ryan, Daniel F.; Bowen, Trevor A.; Chamberlin, Philip C.;
Milligan, Ryan O.; Gallagher, Peter T.
2013enss.confE.133R Altcode:
A solar flare's filling factor is the fraction of its total volume
which is occupied by high density emitting plasma. This is a completely
unknown factor and a major source of uncertainty in many studies
requiring density calculations. While the filling factor is usually
assumed to be unity, tentative observational evidence suggests it may
be orders of magnitude less than that. This would have significant
consequences on past and future flare density and emission measure
analyses. In this poster we examine several C-class events and present
the first observational calculations of flare filling factors using
GOES/XRS, SDO/EVE and SDO/AIA. We find that filling factors are indeed
orders of magnitude less than unity. The sample in this study ranges
from 10-1 - 10-6, with a mean of 10-2.4 and a median of 10-3.4.

---------------------------------------------------------
Title: An Examination of Flare Cooling Using SDO/EVE
Authors: Ryan, Daniel F.; Chamberlin, Phil C.; Gallagher, Peter T.;
Milligan, Ryan O.
2013enss.confE.144R Altcode:
The processes by which solar flares cool have been modeled many times
using magnetohydrodynamic simulations. However, few studies have tried
to compare the results of such models to observations of large numbers
of flares. A better observational understanding of flare cooling would
help us to better constrain initial flare energy inputs and better
understand how potentially harmful radiation is released into the solar
system. The advent of SDO/EVE allows us to observe flare cooling more
directly than before while making fewer assumptions (e.g. the isothermal
assumption). This is done by charting the temporal evolution from
several temperature sensitive lines within the EVE spectral range. In
this poster we have used SDO/EVE and GOES/XRS to calculate flare cooling
profiles of 72 M- and X-class flares. The observed cooling times have
been compared to those predicted by the simple and highly idealized
Cargill et al. (1995) model. We find that although the model does not
accurately fit the distribution, the agreement is still better than
expected, particularly at shorter cooling times.

---------------------------------------------------------
Title: Solar Flare Prediction Using Advanced Feature Extraction,
Machine Learning, and Feature Selection
Authors: Ahmed, Omar W.; Qahwaji, Rami; Colak, Tufan; Higgins, Paul
A.; Gallagher, Peter T.; Bloomfield, D. Shaun
2013SoPh..283..157A Altcode: 2011SoPh..tmp..404A
Novel machine-learning and feature-selection algorithms have been
developed to study: i) the flare-prediction-capability of magnetic
feature (MF) properties generated by the recently developed Solar
Monitor Active Region Tracker (SMART); ii) SMART's MF properties that
are most significantly related to flare occurrence. Spatiotemporal
association algorithms are developed to associate MFs with flares
from April 1996 to December 2010 in order to differentiate flaring
and non-flaring MFs and enable the application of machine-learning and
feature-selection algorithms. A machine-learning algorithm is applied to
the associated datasets to determine the flare-prediction-capability of
all 21 SMART MF properties. The prediction performance is assessed using
standard forecast-verification measures and compared with the prediction
measures of one of the standard technologies for flare-prediction
that is also based on machine-learning: Automated Solar Activity
Prediction (ASAP). The comparison shows that the combination of SMART
MFs with machine-learning has the potential to achieve more accurate
flare-prediction than ASAP. Feature-selection algorithms are then
applied to determine the MF properties that are most related to flare
occurrence. It is found that a reduced set of six MF properties can
achieve a similar degree of prediction accuracy as the full set of 21
SMART MF properties.

---------------------------------------------------------
Title: TEBBS: A New Automatic Method for Calculating
Background-Subtracted Thermal Flare Properties Using GOES/XRS
Authors: Ryan, Daniel F.; Milligan, Ryan O.; Gallagher, Peter T.;
Dennis, Brian R.; Tolbert, A. Kim; Schwartz, Richard A.; Young, C. Alex
2013enss.confE.143R Altcode:
The GOES/XRS has become a "standard candle" by which flare observations
from other satellites are compared. It is increasingly being used
alongside SDO to help us better understand solar flares. In addition,
the longevity of GOES makes it uniquely suited to the study of large
numbers of flares over multiple solar cycles. However, in order to
use the GOES/XRS to accurately derive flare thermal properties, it is
essential to adequately subtract emission from non-flaring plasma. To
date, the potential of the GOES/XRS has been limited by the lack
of standard background subtraction method, capable of being quickly
and automatically applied to any number of flares. In this poster we
present just such a method, the Temperature and Emission measure-Based
Background Subtraction (TEBBS; Ryan et al. 2012). This method calculates
a flare's thermal properties (temperature, emission measure etc.) by
first automatically determining a suitable background subtraction based
on the physical credibility of the results it produces. This method
increases the GOES/XRS's potential both as a stand-alone instrument
as well as in complimenting observations made by SDO and other solar
observatories.

---------------------------------------------------------
Title: The Coronal Pulse Identification and Tracking Algorithm
(CorPITA)
Authors: Long, David M.; Bloomfield, D. Shaun; Feeney-Barry, R.;
Gallagher, Peter T.; Pérez-Suárez, David
2013enss.confE..68L Altcode:
The Coronal Pulse Identification and Tracking Algorithm (CorPITA) is an
automated technique for detecting and analysing "EIT Waves" in data from
the Solar Dynamics Observatory (SDO) spacecraft. CorPITA will operate as
part of the Heliophysics Event Knowledgebase (HEK), providing unbiased,
near-real-time identification of coronal pulses. When triggered by
the start of a solar flare, the algorithm uses an intensity profile
technique radiating from the source of the flare to examine the entire
solar disk. If a pulse is identified, the kinematics and morphological
variation of the pulse are determined for all directions along the
solar surface. Here, CorPITA is applied to a test data-set encompassing
a series of solar flares of different classes from 13-20 February
2011. This allows the effectiveness of the algorithm in dealing with
the varied morphology of different eruptions to be characterised. The
automated nature of this approach will enable an unbiased examination of
"EIT Waves" and their relationship to coronal mass ejections.

---------------------------------------------------------
Title: Evidence for partial Taylor relaxation from changes in magnetic
geometry and energy during a solar flare
Authors: Murray, S. A.; Bloomfield, D. S.; Gallagher, P. T.
2013A&A...550A.119M Altcode: 2012arXiv1212.5906M
Context. Solar flares are powered by energy stored in the coronal
magnetic field, a portion of which is released when the field
reconfigures into a lower energy state. Investigation of sunspot
magnetic field topology during flare activity is useful to improve our
understanding of flaring processes. Aims: Here we investigate
the deviation of the non-linear field configuration from that of
the linear and potential configurations, and study the free energy
available leading up to and after a flare. Methods: The evolution
of the magnetic field in NOAA region 10953 was examined using data from
Hinode/SOT-SP, over a period of 12 h leading up to and after a GOES B1.0
flare. Previous work on this region found pre- and post-flare changes in
photospheric vector magnetic field parameters of flux elements outside
the primary sunspot. 3D geometry was thus investigated using potential,
linear force-free, and non-linear force-free field extrapolations
in order to fully understand the evolution of the field lines. Results: Traced field line geometrical and footpoint orientation
differences show that the field does not completely relax to a fully
potential or linear force-free state after the flare. Magnetic and free
magnetic energies increase significantly ~6.5-2.5 h before the flare
by ~1031 erg. After the flare, the non-linear force-free
magnetic energy and free magnetic energies decrease but do not return to
pre-flare "quiet" values. Conclusions: The post-flare non-linear
force-free field configuration is closer (but not equal) to that of the
linear force-free field configuration than a potential one. However,
the small degree of similarity suggests that partial Taylor relaxation
has occurred over a time scale of ~3-4 h.

---------------------------------------------------------
Title: Spectrometer Telescope for Imaging X-rays (STIX)
Authors: Benz, A. O.; Gallagher, P.; Veronig, A.; Grimm, O.; Sylwester,
J.; Orleanski, P.; Arnold, N.; Bednarzik, M.; Farnik, F.; Hurford,
G.; Krucker, S.; Limousin, O.; Mann, G.; Vilmer, N.
2012IAUSS...6E.509B Altcode:
The Solar Orbiter Mission has been confirmed within ESA's M-class
Cosmic Vision plan. Launch date is January 2017 into an orbit that
reaches nearly one quarter AU in the perihelion. STIX is one of
the 10 instruments selected for close cooperation. STIX applies
a Fourier-imaging technique using shading tungsten grids. A total
of 32 pixelized CdTe detectors will permit high resolution imaging
spectroscopy. The design has passed ESA's Preliminary Design Review
and will be finalized by the end of 2012. The instrument specification
will be presented and its scientific potential discussed.

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Title: The Thermal Properties of Solar Flares over Three Solar Cycles
Using GOES X-Ray Observations
Authors: Ryan, Daniel F.; Milligan, Ryan O.; Gallagher, Peter T.;
Dennis, Brian R.; Tolbert, A. Kim; Schwartz, Richard A.; Young, C. Alex
2012ApJS..202...11R Altcode: 2012arXiv1206.1005R
Solar flare X-ray emission results from rapidly increasing temperatures
and emission measures in flaring active region loops. To date,
observations from the X-Ray Sensor (XRS) on board the Geostationary
Operational Environmental Satellite (GOES) have been used to derive
these properties, but have been limited by a number of factors,
including the lack of a consistent background subtraction method capable
of being automatically applied to large numbers of flares. In this
paper, we describe an automated Temperature and Emission measure-Based
Background Subtraction method (TEBBS), that builds on the methods of
Bornmann. Our algorithm ensures that the derived temperature is always
greater than the instrumental limit and the pre-flare background
temperature, and that the temperature and emission measure are
increasing during the flare rise phase. Additionally, TEBBS utilizes
the improved estimates of GOES temperatures and emission measures
from White et al. TEBBS was successfully applied to over 50,000 solar
flares occurring over nearly three solar cycles (1980-2007), and used to
create an extensive catalog of the solar flare thermal properties. We
confirm that the peak emission measure and total radiative losses
scale with background subtracted GOES X-ray flux as power laws, while
the peak temperature scales logarithmically. As expected, the peak
emission measure shows an increasing trend with peak temperature,
although the total radiative losses do not. While these results are
comparable to previous studies, we find that flares of a given GOES
class have lower peak temperatures and higher peak emission measures
than previously reported. The TEBBS database of flare thermal plasma
properties is publicly available at http://www.SolarMonitor.org/TEBBS/.

---------------------------------------------------------
Title: LEMUR: Large European module for solar Ultraviolet
Research. European contribution to JAXA's Solar-C mission
Authors: Teriaca, Luca; Andretta, Vincenzo; Auchère, Frédéric;
Brown, Charles M.; Buchlin, Eric; Cauzzi, Gianna; Culhane, J. Len;
Curdt, Werner; Davila, Joseph M.; Del Zanna, Giulio; Doschek, George
A.; Fineschi, Silvano; Fludra, Andrzej; Gallagher, Peter T.; Green,
Lucie; Harra, Louise K.; Imada, Shinsuke; Innes, Davina; Kliem,
Bernhard; Korendyke, Clarence; Mariska, John T.; Martínez-Pillet,
Valentin; Parenti, Susanna; Patsourakos, Spiros; Peter, Hardi; Poletto,
Luca; Rutten, Robert J.; Schühle, Udo; Siemer, Martin; Shimizu,
Toshifumi; Socas-Navarro, Hector; Solanki, Sami K.; Spadaro, Daniele;
Trujillo-Bueno, Javier; Tsuneta, Saku; Dominguez, Santiago Vargas;
Vial, Jean-Claude; Walsh, Robert; Warren, Harry P.; Wiegelmann,
Thomas; Winter, Berend; Young, Peter
2012ExA....34..273T Altcode: 2011ExA...tmp..135T; 2011arXiv1109.4301T
The solar outer atmosphere is an extremely dynamic environment
characterized by the continuous interplay between the plasma and the
magnetic field that generates and permeates it. Such interactions play a
fundamental role in hugely diverse astrophysical systems, but occur at
scales that cannot be studied outside the solar system. Understanding
this complex system requires concerted, simultaneous solar observations
from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at
high spatial resolution (between 0.1” and 0.3”), at high temporal
resolution (on the order of 10 s, i.e., the time scale of chromospheric
dynamics), with a wide temperature coverage (0.01 MK to 20 MK,
from the chromosphere to the flaring corona), and the capability of
measuring magnetic fields through spectropolarimetry at visible and
near-infrared wavelengths. Simultaneous spectroscopic measurements
sampling the entire temperature range are particularly important. These
requirements are fulfilled by the Japanese Solar-C mission (Plan B),
composed of a spacecraft in a geosynchronous orbit with a payload
providing a significant improvement of imaging and spectropolarimetric
capabilities in the UV, visible, and near-infrared with respect to
what is available today and foreseen in the near future. The Large
European Module for solar Ultraviolet Research (LEMUR), described
in this paper, is a large VUV telescope feeding a scientific payload
of high-resolution imaging spectrographs and cameras. LEMUR consists
of two major components: a VUV solar telescope with a 30 cm diameter
mirror and a focal length of 3.6 m, and a focal-plane package composed
of VUV spectrometers covering six carefully chosen wavelength ranges
between 170 Å and 1270 Å. The LEMUR slit covers 280” on the Sun with
0.14” per pixel sampling. In addition, LEMUR is capable of measuring
mass flows velocities (line shifts) down to 2 km s - 1 or
better. LEMUR has been proposed to ESA as the European contribution
to the Solar C mission.

---------------------------------------------------------
Title: Studying Sun-Planet Connections Using the Heliophysics
Integrated Observatory (HELIO)
Authors: Pérez-Suárez, D.; Maloney, S. A.; Higgins, P. A.;
Bloomfield, D. S.; Gallagher, P. T.; Pierantoni, G.; Bonnin, X.;
Cecconi, B.; Alberti, V.; Bocchialini, K.; Dierckxsens, M.; Opitz,
A.; Le Blanc, A.; Aboudarham, J.; Bentley, R. B.; Brooke, J.; Coghlan,
B.; Csillaghy, A.; Jacquey, C.; Lavraud, B.; Messerotti, M.
2012SoPh..280..603P Altcode: 2012SoPh..tmp..215P
The Heliophysics Integrated Observatory (HELIO) is a software
infrastructure involving a collection of web services, heliospheric
data sources (e.g., solar, planetary, etc.), and event catalogues -
all of which are accessible through a unified front end. In this
paper we use the HELIO infrastructure to perform three case studies
based on solar events that propagate through the heliosphere. These
include a coronal mass ejection that intersects both Earth and Mars,
a solar energetic particle event that crosses the orbit of Earth, and
a high-speed solar wind stream, produced by a coronal hole, that is
observed in situ at Earth (L1). A ballistic propagation model is run as
one of the HELIO services and used to model these events, predicting
if they will interact with a spacecraft or planet and determining the
associated time of arrival. The HELIO infrastructure streamlines the
method used to perform these kinds of case study by centralising the
process of searching for and visualising data, indicating interesting
features on the solar disk, and finally connecting remotely observed
solar features with those detected by in situ solar wind and energetic
particle instruments. HELIO represents an important leap forward in
European heliophysics infrastructure by bridging the boundaries of
traditional scientific domains.

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Title: Observations of Low Frequency Solar Radio Bursts from the
Rosse Solar-Terrestrial Observatory
Authors: Zucca, P.; Carley, E. P.; McCauley, J.; Gallagher, P. T.;
Monstein, C.; McAteer, R. T. J.
2012SoPh..280..591Z Altcode: 2012SoPh..tmp...94Z; 2012arXiv1204.0943Z
The Rosse Solar-Terrestrial Observatory (RSTO; www.rosseobservatory.ie)
was established at Birr Castle, Co. Offaly, Ireland (53°05'38.9″,
7°55'12.7″) in 2010 to study solar radio bursts and the response of
the Earth's ionosphere and geomagnetic field. To date, three Compound
Astronomical Low-cost Low-frequency Instrument for Spectroscopy in
Transportable Observatory (CALLISTO) spectrometers have been installed,
with the capability of observing in the frequency range of 10 - 870
MHz. The receivers are fed simultaneously by biconical and log-periodic
antennas. Nominally, frequency spectra in the range of 10 - 400 MHz
are obtained with four sweeps per second over 600 channels. Here, we
describe the RSTO solar radio spectrometer set-up, and present dynamic
spectra of samples of type II, III and IV radio bursts. In particular,
we describe the fine-scale structure observed in type II bursts,
including band splitting and rapidly varying herringbone features.

---------------------------------------------------------
Title: The spectrometer telescope for imaging x-rays on board the
Solar Orbiter mission
Authors: Benz, A. O.; Krucker, S.; Hurford, G. J.; Arnold, N. G.;
Orleanski, P.; Gröbelbauer, H. -P.; Klober, S.; Iseli, L.; Wiehl,
H. J.; Csillaghy, A.; Etesi, L.; Hochmuth, N.; Battaglia, M.;
Bednarzik, M.; Resanovic, R.; Grimm, O.; Viertel, G.; Commichau, V.;
Meuris, A.; Limousin, O.; Brun, S.; Vilmer, N.; Skup, K. R.; Graczyk,
R.; Stolarski, M.; Michalska, M.; Nowosielski, W.; Cichocki, A.;
Mosdorf, M.; Seweryn, K.; Przepiórka, A.; Sylwester, J.; Kowalinski,
M.; Mrozek, T.; Podgorski, P.; Mann, G.; Aurass, H.; Popow, E.;
Onel, H.; Dionies, F.; Bauer, S.; Rendtel, J.; Warmuth, A.; Woche,
M.; Plüschke, D.; Bittner, W.; Paschke, J.; Wolker, D.; Van Beek,
H. F.; Farnik, F.; Kasparova, J.; Veronig, A. M.; Kienreich, I. W.;
Gallagher, P. T.; Bloomfield, D. S.; Piana, M.; Massone, A. M.;
Dennis, B. R.; Schwarz, R. A.; Lin, R. P.
2012SPIE.8443E..3LB Altcode:
The Spectrometer Telescope for Imaging X-rays (STIX) is one of 10
instruments on board Solar Orbiter, a confirmed Mclass mission of the
European Space Agency (ESA) within the Cosmic Vision program scheduled
to be launched in 2017. STIX applies a Fourier-imaging technique
using a set of tungsten grids (at pitches from 0.038 to 1 mm) in
front of 32 pixelized CdTe detectors to provide imaging spectroscopy
of solar thermal and non-thermal hard X-ray emissions from 4 to 150
keV. The status of the instrument reviewed in this paper is based on
the design that passed the Preliminary Design Review (PDR) in early
2012. Particular emphasis is given to the first light of the detector
system called Caliste-SO.

---------------------------------------------------------
Title: Investigating the Driving Mechanisms of Coronal Mass Ejections
Authors: Lin, C.; Gallagher, P. T.; Raftery, C. L.
2012ASPC..454..403L Altcode:
The objective of this investigation was to first examine the kinematics
of coronal mass ejections (CMEs) using EUV and coronagraph images,
and then to make a comparison with theoretical models in the hope to
identify the driving mechanisms of the CMEs. We have studied two CMEs
which occurred on 2006 Dec. 17 (CME06) and 2007 Dec. 31 (CME07). The
models studied in this work were catastrophe, breakout, and toroidal
instability models. We found that after the eruption, the accelerations
of both events exhibited a drop before increasing again. Our comparisons
with the theories suggested that CME06 can be best described by a
hybrid of the catastrophe and breakout models while CME07 is most
consistent with the breakout model. Based on the catastrophe model,
we deduced that the reconnection rate in the current sheet for CME06
was intermediate, the onset of its eruption occurred at a height of
∼200 Mm, and the Alfvén speed and the magnetic field strength at
this height were ∼130-250 km s-1 and 7 Gauss, respectively.

---------------------------------------------------------
Title: CORIMP CME Catalogue: Automatically Detecting &amp; Tracking
CMEs in Coronagraph Data
Authors: Byrne, Jason Phelim; Morgan, Huw; Habbal, Shadia; Gallagher,
Peter
2012shin.confE..91B Altcode:
With the large amounts of CME image data available from the SOHO and
STEREO coronagraphs, manual cataloguing of events can be tedious and
subject to user bias. Therefore automated catalogues, such as CACTus
and SEEDS, have been developed in an effort to produce a robust method
of detection and analysis of events. Here we present the development
of a new CORIMP (coronal image processing) CME detection and tracking
technique that overcomes many of the drawbacks of previous methods. It
works by first employing a dynamic CME separation technique to remove
the static background, and then characterizing CMEs via a multiscale
edge-detection algorithm. This allows the inherent structure of
the CMEs to be revealed in each image, which is usually prone to
spatiotemporal crosstalk as a result of traditional image-differencing
techniques. Thus the kinematic and morphological information on
each event is resolved with higher accuracy than previous catalogues,
revealing CME acceleration and expansion profiles otherwise undetected,
and enabling a determination of the varying speeds attained across
the span of the CME. The potential for a 3D characterization of the
internal structure of CMEs is also demonstrated.

---------------------------------------------------------
Title: Automatic Detection and Tracking of Coronal Mass
Ejections. II. Multiscale Filtering of Coronagraph Images
Authors: Byrne, Jason P.; Morgan, Huw; Habbal, Shadia R.; Gallagher,
Peter T.
2012ApJ...752..145B Altcode: 2012arXiv1207.6125B
Studying coronal mass ejections (CMEs) in coronagraph data can be
challenging due to their diffuse structure and transient nature,
and user-specific biases may be introduced through visual inspection
of the images. The large amount of data available from the Solar and
Heliospheric Observatory (SOHO), Solar TErrestrial RElations Observatory
(STEREO), and future coronagraph missions also makes manual cataloging
of CMEs tedious, and so a robust method of detection and analysis is
required. This has led to the development of automated CME detection
and cataloging packages such as CACTus, SEEDS, and ARTEMIS. Here, we
present the development of a new CORIMP (coronal image processing)
CME detection and tracking technique that overcomes many of the
drawbacks of current catalogs. It works by first employing the
dynamic CME separation technique outlined in a companion paper, and
then characterizing CME structure via a multiscale edge-detection
algorithm. The detections are chained through time to determine the
CME kinematics and morphological changes as it propagates across the
plane of sky. The effectiveness of the method is demonstrated by its
application to a selection of SOHO/LASCO and STEREO/SECCHI images,
as well as to synthetic coronagraph images created from a model corona
with a variety of CMEs. The algorithms described in this article are
being applied to the whole LASCO and SECCHI data sets, and a catalog
of results will soon be available to the public.

---------------------------------------------------------
Title: Coronal Mass Ejection Mass, Energy, and Force Estimates
Using STEREO
Authors: Carley, Eoin P.; McAteer, R. T. James; Gallagher, Peter T.
2012ApJ...752...36C Altcode: 2012arXiv1204.4601C
Understanding coronal mass ejection (CME) energetics and dynamics has
been a long-standing problem, and although previous observational
estimates have been made, such studies have been hindered by large
uncertainties in CME mass. Here, the two vantage points of the Solar
Terrestrial Relations Observatory (STEREO) COR1 and COR2 coronagraphs
were used to accurately estimate the mass of the 2008 December 12
CME. Acceleration estimates derived from the position of the CME front
in three dimensions were combined with the mass estimates to calculate
the magnitude of the kinetic energy and driving force at different
stages of the CME evolution. The CME asymptotically approaches a mass of
3.4 ± 1.0 × 1015 g beyond ~10 R ⊙. The kinetic
energy shows an initial rise toward 6.3 ± 3.7 × 1029
erg at ~3 R ⊙, beyond which it rises steadily to 4.2 ±
2.5 × 1030 erg at ~18 R ⊙. The dynamics are
described by an early phase of strong acceleration, dominated by a
force of peak magnitude of 3.4 ± 2.2 × 1014 N at ~3 R
⊙, after which a force of 3.8 ± 5.4 × 1013
N takes effect between ~7 and 18 R ⊙. These results are
consistent with magnetic (Lorentz) forces acting at heliocentric
distances of lsim7 R ⊙, while solar wind drag forces
dominate at larger distances (gsim7 R ⊙).

---------------------------------------------------------
Title: HELIO - A Research Environment for Heliophysics
Authors: Bentley, R. D.; Abourdarham, J.; Csillaghy, A.; Messerotti,
M.; Gallagher, P.; Bocchialini, K.; Jacquey, C.; Hapgood, M.
2012EGUGA..1411634B Altcode:
HELIO, the Heliophysics Integrated Observatory, is a research
infrastructure funded under Capacities programme of the EC's 7th
Framework Programme (FP7). It provides a collaborative environment where
scientists can discover, understand and model the connection between
solar phenomena, interplanetary disturbances and their effects on the
planets. The project is designed around a service-oriented architecture
with needed capabilities that support metadata curation and search,
data location and retrieval, and data processing and storage being
established as independent services. HELIO provides integrated access
to the data and metadata from the domains that constitute heliophysics
- solar, heliospheric, geophysics and planetary. More than 50 event
catalogues can be used in the search, together with just under 10
feature catalogues; data from more than 150 instruments from nearly
50 observatories can be accessed. A comprehensive user interface
is available and the serves can also be accessed through IDL; a
workflow tool provides the ability to combine services together and
it is possible to execute programmes on demand including propagation
models. We will report on the status of HELIO and the services that are
available and demonstrate how these resources can be used to address
use cases involving multiple spacecraft and modelling. We will also
describe how we hope to combine the tools developed by HELIO into a
Collaborative Research Environment for Heliophysics. We have been
holding a series of Coordinated Data Analysis Workshops (CDAW) in
which we demonstrate the capabilities of the project and participants
are able to use them to address science use cases. Two CDAWs have been
held so far, in Dublin and Trieste; a third will be held in February
2012 in Orsay, and a fourth is planned in May/June 2012. Typical use
cases relate to phenomena propagating from the Sun and being observed
by at least two observatories in different parts of the inner Solar
System. The HELIO Consortium includes thirteen groups from the UK,
France, Ireland, Italy, Switzerland, Spain and the US; the project
started in June 2009 and has a duration of 36 months

---------------------------------------------------------
Title: Toward Reliable Benchmarking of Solar Flare Forecasting Methods
Authors: Bloomfield, D. Shaun; Higgins, Paul A.; McAteer, R. T. James;
Gallagher, Peter T.
2012ApJ...747L..41B Altcode: 2012arXiv1202.5995B
Solar flares occur in complex sunspot groups, but it remains unclear
how the probability of producing a flare of a given magnitude relates
to the characteristics of the sunspot group. Here, we use Geostationary
Operational Environmental Satellite X-ray flares and McIntosh group
classifications from solar cycles 21 and 22 to calculate average
flare rates for each McIntosh class and use these to determine Poisson
probabilities for different flare magnitudes. Forecast verification
measures are studied to find optimum thresholds to convert Poisson
flare probabilities into yes/no predictions of cycle 23 flares. A case
is presented to adopt the true skill statistic (TSS) as a standard
for forecast comparison over the commonly used Heidke skill score
(HSS). In predicting flares over 24 hr, the maximum values of TSS
achieved are 0.44 (C-class), 0.53 (M-class), 0.74 (X-class), 0.54
(&gt;=M1.0), and 0.46 (&gt;=C1.0). The maximum values of HSS are 0.38
(C-class), 0.27 (M-class), 0.14 (X-class), 0.28 (&gt;=M1.0), and 0.41
(&gt;=C1.0). These show that Poisson probabilities perform comparably
to some more complex prediction systems, but the overall inaccuracy
highlights the problem with using average values to represent flaring
rate distributions.

---------------------------------------------------------
Title: The Evolution of Sunspot Magnetic Fields Associated with a
Solar Flare
Authors: Murray, Sophie A.; Bloomfield, D. Shaun; Gallagher, Peter T.
2012SoPh..277...45M Altcode: 2011arXiv1105.1978M; 2011SoPh..tmp..129M; 2011SoPh..tmp..185M;
2011SoPh..tmp..254M
Solar flares occur due to the sudden release of energy stored in
active-region magnetic fields. To date, the precursors to flaring are
still not fully understood, although there is evidence that flaring is
related to changes in the topology or complexity of an active-region's
magnetic field. Here, the evolution of the magnetic field in active
region NOAA 10953 was examined using Hinode/SOT-SP data over a period
of 12 hours leading up to and after a GOES B1.0 flare. A number of
magnetic-field properties and low-order aspects of magnetic-field
topology were extracted from two flux regions that exhibited increased
Ca II H emission during the flare. Pre-flare increases in vertical
field strength, vertical current density, and inclination angle of
≈ 8° toward the vertical were observed in flux elements surrounding
the primary sunspot. The vertical field strength and current density
subsequently decreased in the post-flare state, with the inclination
becoming more horizontal by ≈ 7°. This behavior of the field vector
may provide a physical basis for future flare-forecasting efforts.

---------------------------------------------------------
Title: Automated detection and tracking of solar and heliospheric
features in the frame of the European project HELIO
Authors: Bonnin, X.; Aboudarham, J.; Fuller, N.; Renie, C.;
Perez-Suarez, D.; Gallagher, P.; Higgins, P.; Krista, L.; Csillaghy,
A.; Bentley, R.
2011sf2a.conf..373B Altcode:
In the frame of the European project HELIO, the Observatoire de
Paris-Meudon is in charge of the Heliophysics Feature Catalogue (HFC),
a service which provides access to existing solar and heliospheric
feature data. In order to create a catalogue as exhaustive as possible,
recognition codes are developed to automatically detect and track
features. At the time, HFC contains data of filaments, active regions,
coronal holes, sunspots and type III radio bursts for a full solar
cycle. The insertion of prominences and type II radio bursts should
be done in the short term. We present here an overview of some of
the algorithms used to populate HFC. The development of such fast
and robust techniques also addresses the needs of the Space Weather
community in terms of near real-time monitoring capabilities.

---------------------------------------------------------
Title: Active Regions and the Global Magnetic Field of the Sun
Authors: Higgins, P. A.; Bloomfield, D. S.; Gallagher, P. T.
2011AGUFMSH43B1940H Altcode:
The Sun follows an 11 year activity cycle, over which the global
magnetic field begins highly dipolar, and becomes more complex at
cycle maximum, until reverting back to a dipole state, but with
reversed polarity. Many magnetic structures of varying complexity
(active regions) are observed to emerge, evolve, and decay over
the cycle. Beyond location and orientation, the dependence of active
region magnetic properties on the phase of the solar cycle is not well
known. Here, we use automated feature detection methods to detect and
characterize thousands of active region detections and statistically
investigate their physical properties. We find that the mean size and
flux of magnetic features on the solar disk is dependent on the phase
of the cycle. We establish a direct connection between the spatial
distribution of active regions on the solar disk and the configuration
of the global solar magnetic field by investigating the polarity
imbalance of feature magnetic flux. Using a global potential field
source surface model, we find that the shape of the global field is
strongly dependent on the large scale distribution of imbalanced flux.

---------------------------------------------------------
Title: Propagation of Coronal Mass Ejections in 3D and the Structure
of the Inner Heliosphere
Authors: Gallagher, P. T.; Byrne, J. P.; Maloney, S. A.; McAteer, J.
2011AGUFMSH34C..02G Altcode:
Solar coronal mass ejections (CMEs) are the most significant drivers
of adverse space weather on Earth, but the physics governing their
propagation through the heliosphere is not well understood. Although
stereoscopic imaging of CMEs with NASA's Solar Terrestrial
Relations Observatory (STEREO) has provided some insight into their
three-dimensional (3D) propagation, the mechanisms governing their
evolution remain unclear because of difficulties in reconstructing
their true 3D structure. In this talk I will describe the use of an
elliptical tie-pointing technique to reconstruct a CME front in 3D,
enabling us to quantify its deflected trajectory from high latitudes
along the ecliptic, and measure its increasing angular width and
propagation. At large distances from the Sun (&gt;7 R_sun), I will
describe how its motion is determined by drag effects in the solar
wind, using ENLIL simulations of the inner heliosphere. By combining
a 3D reconstruction with modelling of the solar wind, we predict an
arrival time within 30 mins of the in-situ detection of the CME at ACE

---------------------------------------------------------
Title: The Wave Properties of Coronal Bright Fronts Observed Using
SDO/AIA
Authors: Long, David M.; DeLuca, Edward E.; Gallagher, Peter T.
2011ApJ...741L..21L Altcode: 2011arXiv1109.5897L
Coronal bright fronts (CBFs) are large-scale wavefronts that propagate
through the solar corona at hundreds of kilometers per second. While
their kinematics have been studied in detail, many questions
remain regarding the temporal evolution of their amplitude and pulse
width. Here, contemporaneous high cadence, multi-thermal observations
of the solar corona from the Solar Dynamic Observatory (SDO) and
Solar TErrestrial RElations Observatory (STEREO) spacecraft are used
to determine the kinematics and expansion rate of a CBF wavefront
observed on 2010 August 14. The CBF was found to have a lower initial
velocity with weaker deceleration in STEREO observations compared
to SDO observations (~340 km s-1 and -72 m s-2
as opposed to ~410 km s-1 and -279 m s-2). The
CBF kinematics from SDO were found to be highly passband-dependent,
with an initial velocity ranging from 379 ± 12 km s-1
to 460 ± 28 km s-1 and acceleration ranging from -128 ±
28 m s-2 to -431 ± 86 m s-2 in the 335 Å and
304 Å passbands, respectively. These kinematics were used to estimate
a quiet coronal magnetic field strength range of ~1-2 G. Significant
pulse broadening was also observed, with expansion rates of ~130 km
s-1 (STEREO) and ~220 km s-1 (SDO). By treating
the CBF as a linear superposition of sinusoidal waves within a Gaussian
envelope, the resulting dispersion rate of the pulse was found to be
~8-13 Mm2 s-1. These results are indicative
of a fast-mode magnetoacoustic wave pulse propagating through an
inhomogeneous medium.

---------------------------------------------------------
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: STEREO Direct Imaging of a Coronal Mass Ejection-driven Shock
to 0.5 AU
Authors: Maloney, Shane A.; Gallagher, Peter T.
2011ApJ...736L...5M Altcode: 2011arXiv1106.1593M
Fast coronal mass ejections (CMEs) generate standing or bow shocks as
they propagate through the corona and solar wind. Although CME shocks
have previously been detected indirectly via their emission at radio
frequencies, direct imaging has remained elusive due to their low
contrast at optical wavelengths. Here we report the first images of a
CME-driven shock as it propagates through interplanetary space from 8 R
sun to 120 R sun (0.5 AU), using observations from
the STEREO Heliospheric Imager. The CME was measured to have a velocity
of ~1000 km s-1 and a Mach number of 4.1 ± 1.2, while
the shock front standoff distance (Δ) was found to increase linearly
to ~20 R sun at 0.5 AU. The normalized standoff distance
(Δ/DO ) showed reasonable agreement with semi-empirical
relations, where DO is the CME radius. However, when
normalized using the radius of curvature, Δ/RO did not
agree well with theory, implying that RO was underestimated
by a factor of ≈3-8. This is most likely due to the difficulty in
estimating the larger radius of curvature along the CME axis from the
observations, which provide only a cross-sectional view of the CME.

---------------------------------------------------------
Title: Deceleration and dispersion of large-scale coronal bright
fronts
Authors: Long, D. M.; Gallagher, P. T.; McAteer, R. T. J.; Bloomfield,
D. S.
2011A&A...531A..42L Altcode: 2011arXiv1104.4334L
Context. One of the most dramatic manifestations of solar activity
are large-scale coronal bright fronts (CBFs) observed in extreme
ultraviolet (EUV) images of the solar atmosphere. To date, the
energetics and kinematics of CBFs remain poorly understood, due to
the low image cadence and sensitivity of previous EUV imagers and the
limited methods used to extract the features. Aims: In this
paper, the trajectory and morphology of CBFs was determined in order
to investigate the varying properties of a sample of CBFs, including
their kinematics and pulse shape, dispersion, and dissipation. Methods: We have developed a semi-automatic intensity profiling
technique to extract the morphology and accurate positions of CBFs
in 2.5-10 min cadence images from STEREO/EUVI. The technique was
applied to sequences of 171 Å and 195 Å images from STEREO/EUVI
in order to measure the wave properties of four separate CBF
events. Results: Following launch at velocities of ~240-450
km s-1 each of the four events studied showed significant
negative acceleration ranging from ~-290 to -60 m s-2. The
CBF spatial and temporal widths were found to increase from ~50 Mm
to ~200 Mm and ~100 s to ~1500 s respectively, suggesting that they
are dispersive in nature. The variation in position-angle averaged
pulse-integrated intensity with propagation shows no clear trend
across the four events studied. These results are most consistent
with CBFs being dispersive magnetoacoustic waves. Figures 3-8,
10, 11, 13-15, 17, 18 and the movie are available in electronic form
at <A href="http://www.aanda.org">http://www.aanda.org</A>

---------------------------------------------------------
Title: Large-scale Bright Fronts in the Solar Corona: A Review of
"EIT waves"
Authors: Gallagher, Peter T.; Long, David M.
2011SSRv..158..365G Altcode: 2010SSRv..tmp..184G; 2010arXiv1006.0140G
"EIT waves" are large-scale coronal bright fronts (CBFs)
that were first observed in 195 Å images obtained using the
Extreme-ultraviolet Imaging Telescope (EIT) onboard the Solar and
Heliospheric Observatory ( SOHO). Commonly called "EIT waves", CBFs
typically appear as diffuse fronts that propagate pseudo-radially
across the solar disk at velocities of 100-700 km s-1
with front widths of 50-100 Mm. As their speed is greater than the
quiet coronal sound speed ( c s ≤200 km s-1)
and comparable to the local Alfvén speed ( v A ≤1000
km s-1), they were initially interpreted as fast-mode
magnetoacoustic waves (vf=(cs2 +
vA2)^{1/2}). Their propagation is now known
to be modified by regions where the magnetosonic sound speed varies,
such as active regions and coronal holes, but there is also evidence
for stationary CBFs at coronal hole boundaries. The latter has led to
the suggestion that they may be a manifestation of a processes such
as Joule heating or magnetic reconnection, rather than a wave-related
phenomena. While the general morphological and kinematic properties of
CBFs and their association with coronal mass ejections have now been
well described, there are many questions regarding their excitation
and propagation. In particular, the theoretical interpretation of
these enigmatic events as magnetohydrodynamic waves or due to changes
in magnetic topology remains the topic of much debate.

---------------------------------------------------------
Title: The Evolution and Space Weather Effects of Solar Coronal Holes
Authors: Krista, Larisza Diana; Gallagher, Peter T.
2011shin.confE.163K Altcode:
As solar activity is the foremost important aspect of space weather,
the forecasting of flare and CME related transient geomagnetic storms
has become a primary initiative. Minor magnetic storms caused by
coronal holes (CHs) have also proven to be important due to their
long-lasting and recurrent geomagnetic effects. In order to forecast
CH related geomagnetic storms, the author developed the Coronal Hole
Automated Recognition and Monitoring (CHARM) algorithm to replace
the user-dependent CH detection methods commonly used. CHARM uses an
intensity thresholding method to identify low intensity regions in
EUV or X-ray images. Since CHs are regions of 'open' magnetic field
and predominant polarity, magnetograms were used to differentiate CHs
from other low intensity regions. The Coronal Hole Evolution (CHEVOL)
algorithm was developed and used in conjunction with CHARM to study the
boundary evolution of CHs. It is widely accepted that the short-term
changes in CH boundaries are due to the interchange reconnection between
the CH open field lines and small loops. We determined the magnetic
reconnection rate and the diffusion coefficient at CH boundaries in
order to test the interchange reconnection model. The author also
developed the Minor Storm (MIST) package to link CHs to high-speed
solar wind (HSSW) periods detected at Earth. Using the algorithm
the relationship between CHs, the corresponding HSSW properties,
and geomagnetic indices were studied between 2000-2009. The results
showed a strong correlation between the velocity and HSSW proton plasma
temperature, which indicates that the heating and acceleration of the
solar wind plasma in CHs are closely related, and perhaps caused by
the same mechanism. The research presented here includes analysis of
CHs on small and large spatial/temporal scales, allowing us to further
our understanding of CHs as a whole.

---------------------------------------------------------
Title: Solar magnetic feature detection and tracking for space
weather monitoring
Authors: Higgins, P. A.; Gallagher, P. T.; McAteer, R. T. J.;
Bloomfield, D. S.
2011AdSpR..47.2105H Altcode: 2010arXiv1006.5898H
We present an automated system for detecting, tracking, and cataloging
emerging active regions throughout their evolution and decay using SOHO
Michelson Doppler Interferometer (MDI) magnetograms. The SolarMonitor
Active Region Tracking (SMART) algorithm relies on consecutive
image differencing to remove both quiet-Sun and transient magnetic
features, and region-growing techniques to group flux concentrations
into classifiable features. We determine magnetic properties such
as region size, total flux, flux imbalance, flux emergence rate,
Schrijver’s R-value, R∗ (a modified version of R),
and Falconer’s measurement of non-potentiality. A persistence
algorithm is used to associate developed active regions with emerging
flux regions in previous measurements, and to track regions beyond
the limb through multiple solar rotations. We find that the total
number and area of magnetic regions on disk vary with the sunspot
cycle. While sunspot numbers are a proxy to the solar magnetic field,
SMART offers a direct diagnostic of the surface magnetic field and
its variation over timescale of hours to years. SMART will form the
basis of the active region extraction and tracking algorithm for the
Heliophysics Integrated Observatory (HELIO).

---------------------------------------------------------
Title: HELIO: The Heliophysics Integrated Observatory
Authors: Bentley, R. D.; Csillaghy, A.; Aboudarham, J.; Jacquey, C.;
Hapgood, M. A.; Bocchialini, K.; Messerotti, M.; Brooke, J.; Gallagher,
P.; Fox, P.; Hurlburt, N.; Roberts, D. A.; Duarte, L. Sanchez
2011AdSpR..47.2235B Altcode:
Heliophysics is a new research field that explores the Sun-Solar System
Connection; it requires the joint exploitation of solar, heliospheric,
magnetospheric and ionospheric observations.HELIO, the Heliophysics
Integrated Observatory, will facilitate this study by creating an
integrated e-Infrastructure that has no equivalent anywhere else. It
will be a key component of a worldwide effort to integrate heliophysics
data and will coordinate closely with international organizations to
exploit synergies with complementary domains.HELIO was proposed under a
Research Infrastructure call in the Capacities Programme of the European
Commission’s 7th Framework Programme (FP7). The project was selected
for negotiation in January 2009; following a successful conclusion to
these, the project started on 1 June 2009 and will last for 36 months.

---------------------------------------------------------
Title: Coronal mass ejection detection using wavelets, curvelets
and ridgelets: Applications for space weather monitoring
Authors: Gallagher, P. T.; Young, C. A.; Byrne, J. P.; McAteer,
R. T. J.
2011AdSpR..47.2118G Altcode: 2010arXiv1012.1901G
Coronal mass ejections (CMEs) are large-scale eruptions of plasma and
magnetic field that can produce adverse space weather at Earth and
other locations in the Heliosphere. Due to the intrinsic multiscale
nature of features in coronagraph images, wavelet and multiscale image
processing techniques are well suited to enhancing the visibility of
CMEs and suppressing noise. However, wavelets are better suited to
identifying point-like features, such as noise or background stars,
than to enhancing the visibility of the curved form of a typical CME
front. Higher order multiscale techniques, such as ridgelets and
curvelets, were therefore explored to characterise the morphology
(width, curvature) and kinematics (position, velocity, acceleration)
of CMEs. Curvelets in particular were found to be well suited to
characterising CME properties in a self-consistent manner. Curvelets
are thus likely to be of benefit to autonomous monitoring of CME
properties for space weather applications.

---------------------------------------------------------
Title: The Evolution and Space Weather Effects of Solar Coronal Holes
Authors: Krista, Larisza; Gallagher, P.
2011SPD....42.0705K Altcode: 2011BAAS..43S.0705K
As solar activity is the foremost important aspect of space weather,
the forecasting of flare and CME related transient geomagnetic storms
has become a primary initiative. Minor magnetic storms caused by
coronal holes (CHs) have also proven to be important due to their
long-lasting and recurrent geomagnetic effects. In order to forecast
CH related geomagnetic storms, the author developed the Coronal Hole
Automated Recognition and Monitoring (CHARM) algorithm to replace
the user-dependent CH detection methods commonly used. CHARM uses an
intensity thresholding method to identify low intensity regions in
EUV or X-ray images. Since CHs are regions of "open” magnetic field
and predominant polarity, magnetograms were used to differentiate CHs
from other low intensity regions. The Coronal Hole Evolution (CHEVOL)
algorithm was developed and used in conjunction with CHARM to study the
boundary evolution of CHs. It is widely accepted that the short-term
changes in CH boundaries are due to the interchange reconnection between
the CH open field lines and small loops. We determined the magnetic
reconnection rate and the diffusion coefficient at CH boundaries in
order to test the interchange reconnection model. The author also
developed the Minor Storm (MIST) package to link CHs to high-speed
solar wind (HSSW) periods detected at Earth. Using the algorithm
the relationship between CHs, the corresponding HSSW properties,
and geomagnetic indices were studied between 2000-2009. The results
showed a strong correlation between the velocity and HSSW proton plasma
temperature, which indicates that the heating and acceleration of the
solar wind plasma in CHs are closely related, and perhaps caused by
the same mechanism. The research presented here includes analysis of
CHs on small and large spatial/temporal scales, allowing us to further
our understanding of CHs as a whole.

---------------------------------------------------------
Title: Wavefront Expansion and Dispersion of Coronal Bright Fronts
Authors: Long, David; DeLuca, E.; Gallagher, P.
2011SPD....42.0505L Altcode: 2011BAAS..43S.0505L
The true nature of Coronal Bright Fronts (CBFs; commonly called "EIT
Waves") remains enigmatic despite more than ten years of research. High
cadence contemporaneous observations from the Solar Dynamic
Observatory (SDO) and Solar TErrestrial RElations Observatory (STEREO)
spacecraft are used here to determine the kinematics and dispersion
of a CBF pulse observed on 2010 August 14. The CBF exhibited clear
deceleration with propagation, with lower initial velocity and weaker
deceleration in STEREO observations compared to SDO. The kinematics
of the CBF were found to be highly passband dependent, with the pulse
exhibiting higher initial velocity and stronger deceleration in cooler
passbands. Significant pulse broadening was also measured using both
STEREO ( 55 km/s) andSDO ( 65 km/s) observations. The dispersion rate
of the pulse was derived by modeling the CBF as a linear superposition
of sinusoidal waves within a Gaussian envelope. These results imply
that the observed CBF is a fast-mode magnetoacoustic wave, and allowed
the quiet coronal magnetic field strength to be estimated at 1-2 G.

---------------------------------------------------------
Title: Short-term Evolution of Coronal Hole Boundaries
Authors: Krista, Larisza D.; Gallagher, Peter T.; Bloomfield, D. Shaun
2011ApJ...731L..26K Altcode: 2011arXiv1103.2660K
The interaction of open and closed field lines at coronal hole (CH)
boundaries is widely accepted to be due to interchange magnetic
reconnection. To date, it is unclear how the boundaries vary on short
timescales and at what velocity this occurs. Here, we describe an
automated boundary tracking method used to determine CH boundary
displacements on short timescales. The boundary displacements were
found to be isotropic and to have typical expansion/contraction speeds
of &lt;=2 km s-1, which indicate magnetic reconnection rates
of &lt;=3 × 10-3. The observed displacements were used in
conjunction with the interchange reconnection model to derive typical
diffusion coefficients of &lt;=3 × 1013 cm2
s-1. These results are consistent with an interchange
reconnection process in the low corona driven by the random granular
motions of open and closed fields in the photosphere.

---------------------------------------------------------
Title: Automated Solar Feature Detection for Space Weather
Applications
Authors: Pérez-Suárez, David; Higgins, Paul A.; Bloomfield, D. Shaun;
McAteer, R. T. James; Krista, Larisza D.; Byrne, Jason P.; Gallagher,
Peter. T.
2011asip.book..207P Altcode: 2011arXiv1109.6922P
The solar surface and atmosphere are highly dynamic plasma
environments, which evolve over a wide range of temporal and spatial
scales. Large-scale eruptions, such as coronal mass ejections,
can be accelerated to millions of kilometres per hour in a matter
of minutes, making their automated detection and characterisation
challenging. Additionally, there are numerous faint solar features,
such as coronal holes and coronal dimmings, which are important for
space weather monitoring and forecasting, but their low intensity and
sometimes transient nature makes them problematic to detect using
traditional image processing techniques. These difficulties are
compounded by advances in ground- and space- based instrumentation,
which have increased the volume of data that solar physicists are
confronted with on a minute-by-minute basis; NASA's Solar Dynamics
Observatory for example is returning many thousands of images per hour
(~1.5 TB/day). This chapter reviews recent advances in the application
of images processing techniques to the automated detection of active
regions, coronal holes, filaments, CMEs, and coronal dimmings for the
purposes of space weather monitoring and prediction.

---------------------------------------------------------
Title: A Bayesian approach to comparing theoretic models to
observational data: A case study from solar flare physics
Authors: Adamakis, S.; Raftery, C. L.; Walsh, R. W.; Gallagher, P. T.
2011arXiv1102.0242A Altcode:
Solar flares are large-scale releases of energy in the solar atmosphere,
which are characterised by rapid changes in the hydrodynamic properties
of plasma from the photosphere to the corona. Solar physicists
have typically attempted to understand these complex events using
a combination of theoretical models and observational data. From a
statistical perspective, there are many challenges associated with
making accurate and statistically significant comparisons between
theory and observations, due primarily to the large number of free
parameters associated with physical models. This class of ill-posed
statistical problem is ideally suited to Bayesian methods. In this
paper, the solar flare studied by Raftery et al. (2009) is reanalysed
using a Bayesian framework. This enables us to study the evolution
of the flare's temperature, emission measure and energy loss in a
statistically self-consistent manner. The Bayesian-based model selection
techniques imply that no decision can be made regarding which of the
conductive or non-thermal beam heating play the most important role
in heating the flare plasma during the impulsive phase of this event.

---------------------------------------------------------
Title: The Solar Cycle Dependence of Active Region Properties
Authors: Higgins, P.; Gallagher, P. T.; Bloomfield, D.
2010AGUFMSH53B..01H Altcode:
The solar cycle dependence of global active region (AR) emergence and
dynamics is analysed using the SolarMonitor Active Region Tracker
(SMART), which automatically detects and characterises magnetic
flux concentrations using full-disk magnetograms. SMART is run on
a magnetogram data set ranging from 1997 to 2009, resulting in
measurements of each AR on disk each day. AR properties such as
heliographic location, orientation, magnetic flux, flux imbalance,
Schrijver's R value, Falconer's WLSG proxy for non-potentiality,
and flare productivity are compared over cycle 23. We find several
solar cycle modulations in the globally summed AR flux which may
help to characterize the subsurface solar dynamo as well as global
magnetic flux transport. The global flare index is better correlated
to the global R value than WLSG or magnetic flux. Also, the emergence
of highly non-potential, flare-productive ARs is found to be more
confined in latitude than ARs in general, with little dependence on
the phase of the solar cycle.

---------------------------------------------------------
Title: Solar Wind Drag and the Kinematics of Interplanetary Coronal
Mass Ejections
Authors: Maloney, Shane A.; Gallagher, Peter T.
2010ApJ...724L.127M Altcode: 2010arXiv1010.0192M
Coronal mass ejections (CMEs) are large-scale ejections of
plasma and magnetic field from the solar corona, which propagate
through interplanetary space at velocities of ~100-2500 km
s-1. Although plane-of-sky coronagraph measurements have
provided some insight into their kinematics near the Sun (&lt;32 R
sun), it is still unclear what forces govern their evolution
during both their early acceleration and later propagation. Here,
we use the dual perspectives of the STEREO spacecraft to derive the
three-dimensional kinematics of CMEs over a range of heliocentric
distances (~2-250 R sun). We find evidence for solar wind
(SW) drag forces acting in interplanetary space, with a fast CME
decelerated and a slow CME accelerated toward typical SW velocities. We
also find that the fast CME showed linear (δ = 1) dependence on the
velocity difference between the CME and the SW, while the slow CME
showed a quadratic (δ = 2) dependence. The differing forms of drag
for the two CMEs indicate the forces responsible for their acceleration
may be different.

---------------------------------------------------------
Title: Observations of Coronal Bright Fronts using SDO/AIA
Authors: Long, D.; Deluca, E. E.; Gallagher, P. T.
2010AGUFMSH23A1825L Altcode:
Coronal bright fronts (CBFs; commonly called “EIT waves”) have
been studied in detail for over ten years but remain a source of much
debate. We present the first observations of a CBF using the Atmospheric
Imaging Assembly (AIA) onboard the Solar Dynamic Observatory (SDO). An
intensity profiling technique is used to automatically identify
the position of the CBF. The resulting kinematics of the pulse
are studied in detail, with the CBF exhibiting clear deceleration
with propagation. The multi-wavelength capabilities of SDO/AIA are
also used to examine the CBF across multiple passbands. The CBF is
evident in both the 193 and 211~Å passbands, with the 171~Å passband
showing no clear CBF signal in contrast to previous observations from
other space-based instruments. Comparing these results with similar
observations from STEREO/EUVI, we suggest that CBFs may best be
approximated as freely-propagating magneto-acoustic waves.

---------------------------------------------------------
Title: Quantifying the Evolving Magnetic Structure of Active Regions
Authors: Conlon, Paul A.; McAteer, R. T. James; Gallagher, Peter T.;
Fennell, Linda
2010ApJ...722..577C Altcode:
The topical and controversial issue of parameterizing the magnetic
structure of solar active regions has vital implications in the
understanding of how these structures form, evolve, produce solar
flares, and decay. This interdisciplinary and ill-constrained problem of
quantifying complexity is addressed by using a two-dimensional wavelet
transform modulus maxima (WTMM) method to study the multifractal
properties of active region photospheric magnetic fields. The
WTMM method provides an adaptive space-scale partition of a fractal
distribution, from which one can extract the multifractal spectra. The
use of a novel segmentation procedure allows us to remove the quiet Sun
component and reliably study the evolution of active region multifractal
parameters. It is shown that prior to the onset of solar flares, the
magnetic field undergoes restructuring as Dirac-like features (with a
Hölder exponent, h = -1) coalesce to form step functions (where h =
0). The resulting configuration has a higher concentration of gradients
along neutral line features. We propose that when sufficient flux is
present in an active region for a period of time, it must be structured
with a fractal dimension greater than 1.2, and a Hölder exponent
greater than -0.7, in order to produce M- and X-class flares. This
result has immediate applications in the study of the underlying
physics of active region evolution and space weather forecasting.

---------------------------------------------------------
Title: Evidence for Internal Tether-cutting in a Flare/Coronal Mass
Ejection Observed by MESSENGER, RHESSI, and STEREO
Authors: Raftery, Claire L.; Gallagher, Peter T.; McAteer, R. T. James;
Lin, Chia-Hsien; Delahunt, Gareth
2010ApJ...721.1579R Altcode:
The relationship between eruptive flares and coronal mass ejections
(CMEs) is a topic of ongoing debate, especially regarding the
possibility of a common initiation mechanism. We studied the kinematic
and hydrodynamic properties of a well-observed event that occurred
on 2007 December 31 using data from MESSENGER, RHESSI, and STEREO
in order to gain new physical insight into the evolution of the
flare and CME. The initiation mechanism was determined by comparing
observations to the internal tether-cutting, breakout, and ideal
magnetohydrodynamic (MHD) models. Evidence of pre-eruption reconnection
immediately eliminated the ideal MHD model. The timing and location of
the soft and hard X-ray sources led to the conclusion that the event
was initiated by the internal tether-cutting mechanism. In addition,
a thermal source was observed to move in a downward direction during
the impulsive phase of the event, followed by upward motion during the
decay phase, providing evidence for X- to Y-type magnetic reconnection.

---------------------------------------------------------
Title: Propagation of an Earth-directed coronal mass ejection in
three dimensions
Authors: Byrne, Jason P.; Maloney, Shane A.; McAteer, R. T. James;
Refojo, Jose M.; Gallagher, Peter T.
2010NatCo...1...74B Altcode: 2010NatCo...1E..74B; 2010arXiv1010.0643B
Solar coronal mass ejections (CMEs) are the most significant drivers
of adverse space weather on Earth, but the physics governing their
propagation through the heliosphere is not well understood. Although
stereoscopic imaging of CMEs with NASA's Solar Terrestrial
Relations Observatory (STEREO) has provided some insight into their
three-dimensional (3D) propagation, the mechanisms governing their
evolution remain unclear because of difficulties in reconstructing their
true 3D structure. In this paper, we use a new elliptical tie-pointing
technique to reconstruct a full CME front in 3D, enabling us to quantify
its deflected trajectory from high latitudes along the ecliptic, and
measure its increasing angular width and propagation from 2 to 46
(~0.2 AU). Beyond 7 , we show that its motion is determined by an
aerodynamic drag in the solar wind and, using our reconstruction as
input for a 3D magnetohydrodynamic simulation, we determine an accurate
arrival time at the Lagrangian L1 point near Earth.

---------------------------------------------------------
Title: Characterizing complexity in solar magnetogram data using a
wavelet-based segmentation method
Authors: Kestener, Pierre; Khalil, André; Arneodo, Alain; Conlon,
P.; McAteer, J.; Gallagher, P.
2010ada..confE..24K Altcode: 2010arXiv1005.1536K
The multifractal nature of solar photospheric magnetic structures
are studied using the 2D wavelet transform modulus maxima (WTMM)
method. This relies on computing partition functions from the wavelet
transform skeleton defined by the WTMM method. This skeleton provides
an adaptive space-scale partition of the fractal distribution under
study, from which one can extract the multifractal singularity
spectrum. We describe the implementation of a multiscale image
processing segmentation procedure based on the partitioning of the WT
skeleton which allows the disentangling of the information concerning
the multifractal properties of active regions from the surrounding
quiet-Sun field. The quiet Sun exhibits a average Hölder exponent $\sim
-0.75$, with observed multifractal properties due to the supergranular
structure. On the other hand, active region multifractal spectra exhibit
an average Hölder exponent $\sim 0.38$ similar to those found when
studying experimental data from turbulent flows.

---------------------------------------------------------
Title: Characterizing Complexity in Solar Magnetogram Data Using a
Wavelet-based Segmentation Method
Authors: Kestener, P.; Conlon, P. A.; Khalil, A.; Fennell, L.; McAteer,
R. T. J.; Gallagher, P. T.; Arneodo, A.
2010ApJ...717..995K Altcode:
The multifractal nature of solar photospheric magnetic structures is
studied using the two-dimensional wavelet transform modulus maxima
(WTMM) method. This relies on computing partition functions from
the wavelet transform skeleton defined by the WTMM method. This
skeleton provides an adaptive space-scale partition of the fractal
distribution under study, from which one can extract the multifractal
singularity spectrum. We describe the implementation of a multiscale
image processing segmentation procedure based on the partitioning of
the WT skeleton, which allows the disentangling of the information
concerning the multifractal properties of active regions from the
surrounding quiet-Sun field. The quiet Sun exhibits an average Hölder
exponent ~-0.75, with observed multifractal properties due to the
supergranular structure. On the other hand, active region multifractal
spectra exhibit an average Hölder exponent ~0.38, similar to those
found when studying experimental data from turbulent flows.

---------------------------------------------------------
Title: Investigating the driving mechanisms of coronal mass ejections
Authors: Lin, C. -H.; Gallagher, P. T.; Raftery, C. L.
2010A&A...516A..44L Altcode: 2010arXiv1003.5035L
 Aims: The objective of this study was to examine the kinematics
of coronal mass ejections (CMEs) using EUV and coronagraph images,
and to make a quantitative comparison with a number of theoretical
models. One particular aim was to investigate the acceleration
profile of CMEs in the low corona. Methods: We selected two
CME events for this study, which occurred on 2006 December 17 (CME06)
and 2007 December 31 (CME07). CME06 was observed using the EIT and
LASCO instruments on-board SOHO, while CME07 was observed using the
SECCHI imaging suite on STEREO. The first step of the analysis was
to track the motion of each CME front and derive its velocity and
acceleration. We then compared the observational kinematics, along
with the information of the associated X-ray emissions from GOES and
RHESSI, with the kinematics proposed by three CME models (catastrophe,
breakout and toroidal instability). Results: We found that CME06
lasted over eight hours while CME07 released its energy in less than
three hours. After the eruption, both CMEs were briefly slowed down
before being accelerated again. The peak accelerations during the
re-acceleration phase coincided with the peak soft X-ray emissions
for both CMEs. Their values were ~60 m s-2 for CME06 and
~600 m s-2 for CME07. CME07 reached a maximum speed of over
1000 km s-1 before being slowed down to propagate away at
a constant, final speed of ~700 km s-1. CME06 did not reach
a constant speed but was moving at a small acceleration by the end of
the observation. Our comparison with the theories suggested that CME06
can be best described by a hybrid of the catastrophe model and breakout
model while the characteristics of CME07 were most consistent with the
breakout model. Based on the catastrophe model, we deduced that the
reconnection rate in the current sheet for CME06 was intermediate,
the onset of its eruption occurred at a height of ~200 Mm, and the
Alfvén speed and the magnetic field strength at this height were
approximately 130-250 km s-1 and 7 Gauss, respectively.

---------------------------------------------------------
Title: Propagation of an Earth-Directed Coronal Mass Ejection in 3D
Authors: Byrne, Jason; Gallagher, P. T.; Maloney, S. A.; McAteer, J.
2010AAS...21631405B Altcode: 2010BAAS...41..894B
We have developed a new method to reconstruct the 3D evolution of a
CME front using the Sun Earth Connection Coronal and Heliospheric
Investigation (SECCHI) onboard the Solar Terrestrial Relations
Observatory (STEREO). On 12 December 2008 an Earth-directed CME was
observed by STEREO while the spacecraft were in near quadrature at
86.7 degrees separation. This positioning presents an ideal case
for observing its propagation through the combined SECCHI instrument
fields-of-view and applying our technique to reconstruct the CME front
in 3D. The reconstruction allows us to determine the true CME front
kinematics and morphology, and we measure three important dynamic
effects at play: deflection from a high latitude source region; an
increasing angular width; and interplanetary drag.

---------------------------------------------------------
Title: Turbulence, complexity, and solar flares
Authors: McAteer, R. T. James; Gallagher, Peter T.; Conlon, Paul A.
2010AdSpR..45.1067M Altcode: 2009arXiv0909.5636M
The issue of predicting solar flares is one of the most fundamental in
physics, addressing issues of plasma physics, high-energy physics, and
modelling of complex systems. It also poses societal consequences, with
our ever-increasing need for accurate space weather forecasts. Solar
flares arise naturally as a competition between an input (flux emergence
and rearrangement) in the photosphere and an output (electrical
current build up and resistive dissipation) in the corona. Although
initially localised, this redistribution affects neighbouring regions
and an avalanche occurs resulting in large scale eruptions of plasma,
particles, and magnetic field. As flares are powered from the stressed
field rooted in the photosphere, a study of the photospheric magnetic
complexity can be used to both predict activity and understand the
physics of the magnetic field. The magnetic energy spectrum and
multifractal spectrum are highlighted as two possible approaches
to this.

---------------------------------------------------------
Title: Evidence For Internal Tether-cutting in a Flare/CME Event.
Authors: Raftery, Claire; Gallagher, P. T.; McAteer, R. T. J.; Lin,
C. H.; Delahunt, G.
2010AAS...21631403R Altcode: 2010BAAS...41..894R
The relationship between eruptive flares and CMEs is a topic of ongoing
debate, especially regarding the possibility of a common initiation
mechanism. In order to gain new physical insight into this problem,
the kinematic and hydrodynamic properties of a well-observed event were
studied using data from MESSENGER, RHESSI and STEREO/Secchi. These data
were compared to three theoretical models to determine the event's
initiation mechanism. The timing and positioning of EUV and X-ray
sources along with evidence for pre-eruption particle acceleration
led to the conclusion that the event was initiated by the internal
tether-cutting mechanism and was followed by breakout reconnection
some 10 minutes after launch.

---------------------------------------------------------
Title: A Method to Calculate Background-Subtracted Flare Plasma
Parameters Using GOES Over Three Solar Cycles
Authors: Ryan, Daniel; Gallagher, P. T.; Milligan, R. O.; Young, C. A.
2010AAS...21640436R Altcode:
The GOES solar flare catalogue is the largest, self-consistent listing
currently available covering three solar cycles - #21, 22, and 23 -
from 1974 to the present. Solar X-ray flux integrated over the full
solar disk is recorded every 3s in each of the two GOES channels (long;
1-8Å and short; 0.5-4Å). By taking the ratio of the flux in the two
passbands, parameters of the SXR-emitting plasma (e.g. temperature,
emission measure, radiative loss rate etc.) can be derived, as well
as the timescales over which they change. In doing so, it is vital to
perform a suitable background subtraction to remove the influence of
flux not associated with the flaring plasma. Using the method outlined
in Bornmann 1990, we have developed a technique to systematically
derive the flare parameters for all GOES flares from 1980 to present
after accounting for background emission. This then allows us to make
statistically meaningful comparisons between events observed over the
course of the past three solar cycles. This research is generously
funded by the Irish Research Council for Science, Engineering and
Technology (IRCSET).

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Title: Constraining Three-Dimensional Magnetic Field Extrapolations
Using the Twin Perspectives of STEREO
Authors: Conlon, Paul A.; Gallagher, Peter T.
2010ApJ...715...59C Altcode: 2010arXiv1004.1330C
The three-dimensional magnetic topology of a solar active region (NOAA
10956) was reconstructed using a linear force-free field extrapolation
constrained using the twin perspectives of STEREO. A set of coronal
field configurations was initially generated from extrapolations of the
photospheric magnetic field observed by the Michelson Doppler Imager
on SOHO. Using an EUV intensity-based cost function, the extrapolated
field lines that were most consistent with 171 Å passband images
from the Extreme UltraViolet Imager on STEREO were identified. This
facilitated quantitative constraints to be placed on the twist (α)
of the extrapolated field lines, where ∇ × B = αB. Using the
constrained values of α, the evolution in time of twist, connectivity,
and magnetic energy were then studied. A flux emergence event was
found to result in significant changes in the magnetic topology and
total magnetic energy of the region.

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Title: CME Kinematics and Dynamics
Authors: Lin, C. -H.; Gallagher, P. T.
2010ASSP...19..530L Altcode: 2010mcia.conf..530L
The goal of this study is to investigate the driving mechanisms
of CMEs and to infer the magnetic field properties at the onset
of the instability. We use EIT 195 Å images and LASCO white-light
coronagraph data of a CME event that occurred on 17 December 2006. It
was a long-duration event, and was associated with an occulted C2.1
class flare. To determine the driving mechanism, we quantitatively
and qualitatively compared the observationally obtained kinematic
evolution with that predicted by three CME models: the breakout model
(BO, see Antiochos et al. 1999; Lynch et al. 2008; DeVore and Antiochos
2008), the catastrophe model (CM, see Priest and Forbes 2000), and
the toroidal instability model (TI, see Chen 1989; Kliem and Török
2006). Our results indicate that this CME is best represented by the
CM model. We infer that, at the onset of the instability, the Alfvén
speed is approximately 120 km s-1 and the height of the
flux rope is roughly 100-200Mm. These parameter values are related
to the magnetic environment and the loop geometry and can be used to
infer the magnetic condition at the onset of the eruption.We intend
to submit the full analysis to A&amp;A.

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Title: The propagation of a CME front in 3D
Authors: Maloney, Shane; Byrne, Jason; Gallagher, Peter T.; McAteer,
R. T. James
2010cosp...38.1867M Altcode: 2010cosp.meet.1867M
We present a new three-dimensional (3D) reconstruction of an
Earth-directed coronal mass ejec-tion (CME), providing new insight into
the processes that control its evolution and propagation. Previously
limited fields-of-view and single vantage point observations made it
impossible to confidently describe CMEs in 3D. This uncertainty in a
CME's position and geometry made comparison to theory difficult and
hindered progress. Our 3D reconstruction unambiguously shows three
effects at play on the CME: deflection from a high latitude source
region, angular width expansion, and interplanetary drag. The CME
undergoes a deflection of ∼20° degrees below 10 RSun and slowly tends
towards the ecliptic throughout its subsequent propagation. We interpret
this deflection as a direct result of the interplay between the CME and
the drawn-out dipolar topology of the (solar minimum) coronal magnetic
field. The increasing angular width is in excess of that due to simple
spherical expansion in the diverging solar wind so an additional source
of expansion must be present. The additional source is inferred to be
a pressure gradient between the internal pressure (magnetic and gas)
of the flux rope relative to the ambient solar wind pressure. Low in the
corona there is rapid expansion due to a large pressure difference, but
further out the CME approaches equilibrium with the solar wind, and the
angular width tends to a constant. The 3D reconstruction allows us to
accurately determine the CME kinematics, and we show unambiguously that
the interplanetary acceleration is due to aerodynamic drag. Furthermore
we derive parameters from our reconstruction that act as inputs to an
ENLIL model of the CME's propagation to Earth. The results show the
CME undergoes a significant degrease in velocity where it encounters
a slow-speed solar wind stream ahead of it (&gt;50 RSun ). This lower
velocity agrees with the derived velocity from in-situ data at the
L1 point and predicts the correct arrival time, to within minutes. In
our ever-increasingly technological society, the accurate prediction
of adverse space weather is of paramount impor-tance and to achieve
this we must understand the basic processes that govern CMEs. Our
3D reconstruction has allowed us to gain some novel insights into
these processes, and emphasises the dynamic interplay between CMEs
and solar wind.

---------------------------------------------------------
Title: Using HELIO to study cross-disiplinary science problems using
data from multiple spacecraft
Authors: Bentley, Robert; Aboudarham, Jean; Messerotti, Mauro; Jacquey,
Christian; Gallagher, Peter T.; Hapgood, Mike; Bocchialini, Karine
2010cosp...38.1917B Altcode: 2010cosp.meet.1917B
The Heliophysics Integrated Observatory, HELIO, is creating a
collaborative environment where scientists can discover, understand
and model the connection between solar phenomena, inter-planetary
disturbances and their effects on the planets. HELIO will provide
integrated access to data from the solar, heliospheric, geophysics
and plan-etary domains and allow the user to undertake a search for
interesting events and phenomena based solely on metadata and data
products. The HELIO infrastructure will provide services to support
the search that can either be used independently or as part of a work
flow. The services include event and feature catalogues derived from
data from all the domains and a processing capability that will use
models to relate observations made in different part of the solar
system. We will describe how HELIO can be used to address science
problems that span the domains by allowing the user to track phenomena
as they propagate through the solar system and report on progress
to date. HELIO is a research infrastructure funded under Capacities
programme of the EC's 7th Frame-work Programme (FP7); the project
started in June 2009 and has a duration of 36 months. The HELIO
Consortium includes thirteen groups from the UK, France, Ireland,
Italy, Switzerland, Spain and the US.

---------------------------------------------------------
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: Addressing Science Use Cases with HELIO
Authors: Bentley, R. D.; Aboudarham, J.; Csillaghy, A.; Jacquey,
C.; Hapgood, M. A.; Messerotti, M.; Gallagher, P.; Bocchialini, K.;
Hurlburt, N. E.; Roberts, D.; Sanchez Duarte, L.
2009AGUFMSH54A..06B Altcode:
The Heliophysics Integrated Observatory (HELIO) is a new VO project
funded under the EC's Seventh Framework Programme (FP7). It includes
thirteen partners scattered over six countries and is led by University
College London. HELIO is designed to support the heliophysics community
and is based on a Service Oriented Architecture. The services developed
by and integrated into HELIO can be used to address a wide range
of science problems; they can be used individually or as part of a
work-flow driven search engine that can use a propagation (or other)
model to help locate obervations that describe interesting phenomena. We
will describe and discuss how the components of HELIO could be used
to address science use cases, particularly how a user can adapt the
work flow to their own science interests. Networking is one of the
three Activities of the HELIO Integrated Infrastructure Initiatives
(I3) project. Within this activity we plan to involve the community in
all aspects of the design and testing of the HELIO system, including
determining which data and metadata should be included, how the quality
and content of metadata can be included, etc. We are investigating ways
of making HELIO "domain-aware" so that researchers who are specialists
in one of the communities that constitute heliophysics can easily
identify, access and use data they need from the other communities. We
will discuss how the community can help us develop this capability.

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Title: The SolarMonitor Active Region Tracking (SMART) Algorithm:
Variation of magnetic feature properties through solar cycle 23
Authors: Higgins, P.; Gallagher, P.; McAteer, R.; Bloomfield, D.
2009AGUFMSH51B1278H Altcode:
The SolarMonitor Active Region Tracking (SMART) algorithm is an
automated system for detecting, tracking, and cataloging magnetic
features throughout their evolution and decay. The SMART method will
form the basis of active region extraction and tracking within the
Heliophysics Integrated Observatory (HELIO). Magnetic properties
such as total flux, flux imbalance, flux emergence rate, Schrijver's
R-value, R* (a modified version of R), and Falconer's measurement of
non-potentiality are determined for individual features throughout solar
cycle 23. The variation of these feature property distributions with
progression through the solar cycle is presented. Feature detections
using the SMART algorithm for line-of-sight level 1.8 SOHO/MDI
magnetogram taken 22 October 2003 at 12:47. Active region candidates
are denoted "AR", emerging flux concentrations are denoted "EF", plage
regions are denoted "PL" and other flux concentrations are labeled "NF".

---------------------------------------------------------
Title: Automated Coronal Hole Detection Using Local Intensity
Thresholding Techniques
Authors: Krista, Larisza D.; Gallagher, Peter T.
2009SoPh..256...87K Altcode: 2009arXiv0905.1814K
We identify coronal holes using a histogram-based intensity thresholding
technique and compare their properties to fast solar wind streams at
three different points in the heliosphere. The thresholding technique
was tested on EUV and X-ray images obtained using instruments onboard
STEREO, SOHO and Hinode. The full-disk images were transformed into
Lambert equal-area projection maps and partitioned into a series of
overlapping sub-images from which local histograms were extracted. The
histograms were used to determine the threshold for the low intensity
regions, which were then classified as coronal holes or filaments
using magnetograms from the SOHO/MDI. For all three instruments,
the local thresholding algorithm was found to successfully determine
coronal hole boundaries in a consistent manner. Coronal hole properties
extracted using the segmentation algorithm were then compared with
in situ measurements of the solar wind at ∼ 1 AU from ACE and
STEREO. Our results indicate that flux tubes rooted in coronal holes
expand super-radially within 1 AU and that larger (smaller) coronal
holes result in longer (shorter) duration high-speed solar wind streams.

---------------------------------------------------------
Title: Reconstructing the 3-D Trajectories of CMEs in the Inner
Heliosphere
Authors: Maloney, Shane A.; Gallagher, Peter T.; McAteer, R. T. James
2009SoPh..256..149M Altcode: 2009arXiv0905.2153M
A method for the full three-dimensional (3-D) reconstruction of the
trajectories of coronal mass ejections (CMEs) using Solar TErrestrial
RElations Observatory (STEREO) data is presented. Four CMEs that were
simultaneously observed by the inner and outer coronagraphs (COR1
and 2) of the Ahead and Behind STEREO satellites were analysed. These
observations were used to derive CME trajectories in 3-D out to ∼
15 R⊙. The reconstructions using COR1/2 data support a
radial propagation model. Assuming pseudo-radial propagation at large
distances from the Sun (15 - 240 R⊙), the CME positions
were extrapolated into the Heliospheric Imager (HI) field-of-view. We
estimated the CME velocities in the different fields-of-view. It was
found that CMEs slower than the solar wind were accelerated, while
CMEs faster than the solar wind were decelerated, with both tending
to the solar wind velocity.

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Title: The Flare-CME Connection
Authors: Raftery, Claire; Gallagher, P. T.; Lin, C.
2009SPD....40.3701R Altcode:
The connection between flares and CMEs has long been hypothesized
and modelled. However, a full understanding of the processes at work
remains ambiguous. A detailed study of the kinematical evolution of a
CME was conducted using instruments on STEREO. Flare parameters, such
as the motion of soft X-ray sources, imaged using RHESSI, and emission
measure and plasma temperature measured from Mercury MESSENGER are
presented in conjunction with the CME data to explain the evolution
of the entire system. These results are then compared to a number of
theoretical models to determine which of the many hypotheses are most
probable for this event. CLR is supported by an SPD studentship and
the ESA/Prodex grant administered by Enterprise Ireland.

---------------------------------------------------------
Title: Magnetic Fields, Flares &amp; Forecasts
Authors: Conlon, Paul A.; Kestener, P.; McAteer, R.; Gallagher, P.
2009SPD....40.1602C Altcode:
A 2D wavelet transform modulus maxima (WTMM) method is used to
characterise the complexity of the distribution of the photospheric
magnetic field of active regions. The WTMM method offers increased
accuracy and reliability over previous fractal and multifractal
methods. The multifractal spectrum of both quiet Sun and active region
magnetic features are presented. It is shown that the multifractal
nature of the quiet Sun is significantly different from that of
an active region. As such, a method is proposed to seperate the
information corresponding to the multifractal spectrum of an active
region from the surrounding quite Sun texture. The WTMM method and
segmentation procedure are shown to detect the internal restructuring
of active region magnetic features prior to flaring. We detect two
thresholds (Haussdorf dimension &gt; 1.2 and Holder Exponent &gt;
-0.7) as possible indicators for conditions favourable to flaring.

---------------------------------------------------------
Title: The Temperature Response of EUV Imagers
Authors: Raftery, Claire; Bloomfield, D. Shaun; Gallagher, P.
2009SPD....40.1213R Altcode:
The temperature response of an EUV imager provides the user with
the temperature range over which the instrument or passband is
sensitive. These response curves appear to be highly peaked, implying
a narrow range of temperature sensitivity. However, in the past,
these response functions have been calculated using quiet sun spectra
or constant density, assumptions which are relevant only in specific
circumstances. The multithermal response of the EUV imagers - TRACE,
SOHO/EIT, STEREO/EUVI, PROBA2/SWAP and SDO/AIA were investigated. It
was found that a highly peaked response curve is only appropriate
when looking at cooler material. However, studying higher temperature
emission from e.g. active regions and flares produces a very broad,
almost flat response between 105 and 107 K
for all instruments. CLR is supported by an SPD studentship and the
ESA/Prodex grant administered by Enterprise Ireland.

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Title: The kinematics of coronal mass ejections using multiscale
methods
Authors: Byrne, J. P.; Gallagher, P. T.; McAteer, R. T. J.; Young,
C. A.
2009A&A...495..325B Altcode: 2009arXiv0901.3392B
Aims: The diffuse morphology and transient nature of coronal mass
ejections (CMEs) make them difficult to identify and track using
traditional image processing techniques. We apply multiscale methods
to enhance the visibility of the faint CME front. This enables
an ellipse characterisation to objectively study the changing
morphology and kinematics of a sample of events imaged by the
Large Angle Spectrometric Coronagraph (LASCO) onboard the Solar
and Heliospheric Observatory (SOHO) and the Sun Earth Connection
Coronal and Heliospheric Investigation (SECCHI) onboard the Solar
Terrestrial Relations Observatory (STEREO). The accuracy of these
methods allows us to test the CMEs for non-constant acceleration and
expansion. Methods: We exploit the multiscale nature of CMEs
to extract structure with a multiscale decomposition, akin to a Canny
edge detector. Spatio-temporal filtering highlights the CME front as
it propagates in time. We apply an ellipse parameterisation of the
front to extract the kinematics (height, velocity, acceleration)
and changing morphology (width, orientation). Results: The
kinematic evolution of the CMEs discussed in this paper have been
shown to differ from existing catalogues. These catalogues are based
upon running-difference techniques that can lead to over-estimating
CME heights. Our resulting kinematic curves are not well-fitted with
the constant acceleration model. It is shown that some events have
high acceleration below ~5 R⊙. Furthermore, we find that
the CME angular widths measured by these catalogues are over-estimated,
and indeed for some events our analysis shows non-constant CME expansion
across the plane-of-sky.

---------------------------------------------------------
Title: Multi-wavelength observations and modelling of a canonical
solar flare
Authors: Raftery, C. L.; Gallagher, P. T.; Milligan, R. O.; Klimchuk,
J. A.
2009A&A...494.1127R Altcode: 2008arXiv0812.0311R
Aims: We investigate the temporal evolution of temperature, emission
measure, energy loss, and velocity in a C-class solar flare from
both observational and theoretical perspectives. Methods:
The properties of the flare were derived by following the systematic
cooling of the plasma through the response functions of a number of
instruments - the Reuven Ramaty High Energy Solar Spectroscopic Imager
(RHESSI; &gt;5 MK), GOES-12 (5-30 MK), the Transition Region and
Coronal Explorer (TRACE 171 Å; 1 MK), and the Coronal Diagnostic
Spectrometer (CDS; ~0.03-8 MK). These measurements were studied in
combination with simulations from the 0-D enthalpy based thermal
evolution of loops (EBTEL) model. Results: At the flare
onset, upflows of ~90 km s-1 and low-level emission were
observed in Fe XIX, consistent with pre-flare heating and gentle
chromospheric evaporation. During the impulsive phase, upflows of
~80 km s-1 in Fe XIX and simultaneous downflows of ~20 km
s-1 in He I and O V were observed, indicating explosive
chromospheric evaporation. The plasma was subsequently found to reach
a peak temperature of ⪆13 MK in approximately 10 min. Using EBTEL,
conduction was found to be the dominant loss mechanism during the
initial ~300 s of the decay phase. It was also found to be responsible
for driving gentle chromospheric evaporation during this period. As
the temperature fell below ~8 MK, and for the next ~4000 s, radiative
losses were determined to dominate over conductive losses. The
radiative loss phase was accompanied by significant downflows of
≤40 km s-1 in O V. Conclusions: This is the first
extensive study of the evolution of a canonical solar flare using
both spectroscopic and broad-band instruments in conjunction with a
0-D hydrodynamic model. While our results are in broad agreement with
the standard flare model, the simulations suggest that both conductive
and non-thermal beam heating play important roles in heating the flare
plasma during the impulsive phase of at least this event.

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Title: Multiresolution Analysis of Active Region Magnetic Structure
and its Correlation with the Mount Wilson Classification and Flaring
Activity
Authors: Ireland, J.; Young, C. A.; McAteer, R. T. J.; Whelan, C.;
Hewett, R. J.; Gallagher, P. T.
2008SoPh..252..121I Altcode: 2008arXiv0805.0101I; 2008SoPh..tmp..134I
Two different multiresolution analyses are used to decompose the
structure of active-region magnetic flux into concentrations of
different size scales. Lines separating these opposite polarity
regions of flux at each size scale are found. These lines are used as
a mask on a map of the magnetic field gradient to sample the local
gradient between opposite polarity regions of given scale sizes. It
is shown that the maximum, average, and standard deviation of the
magnetic flux gradient for α,β,βγ, and βγδ active-regions
increase in the order listed, and that the order is maintained over
all length scales. Since magnetic flux gradient is strongly linked
to active-region activity, such as flares, this study demonstrates
that, on average, the Mt. Wilson classification encodes the notion
of activity over all length scales in the active-region, and not
just those length scales at which the strongest flux gradients are
found. Further, it is also shown that the average gradients in the
field, and the average length-scale at which they occur, also increase
in the same order. Finally, there are significant differences in the
gradient distribution, between flaring and non-flaring active regions,
which are maintained over all length scales. It is also shown that the
average gradient content of active-regions that have large flares (GOES
class "M" and above) is larger than that for active regions containing
flares of all flare sizes; this difference is also maintained at all
length scales. All of the reported results are independent of the
multiresolution transform used. The implications for the Mt. Wilson
classification of active-regions in relation to the multiresolution
gradient content and flaring activity are discussed.

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Title: IDL Object Oriented Software for Hinode/XRT Image Analysis
Authors: Higgins, P. A.; Gallagher, P. T.
2008ASPC..397..171H Altcode:
We have developed a set of object oriented IDL routines that enable
users to search, download and analyse images from the X-Ray Telescope
(XRT) on-board Hinode. In this paper, we give specific examples of
how the object can be used and how multi-instrument data analysis can
be performed. The XRT object is a highly versatile and powerful IDL
object, which will prove to be a useful tool for solar researchers. This
software utilizes the generic Framework object available within the
GEN branch of SolarSoft.

---------------------------------------------------------
Title: Flare Cooling and Implications for Hinode/EIS
Authors: Raftery, C. L.; Gallagher, P. T.; Milligan, R. O.
2008ASPC..397..184R Altcode:
The cooling of a post-flare loop system as observed by TRACE and
SOHO/CDS, SOHO/EIT, GOES and RHESSI is studied and compared to
the predictions of recent solar flare models. The observed C-class
flare cools from ≥ 10 MK to ∼ 0.25 MK in approximately 45 mins
via conduction and radiation. Using theoretical modelling, conduction
was found to dominate during the first 3 min of the decay phase, after
which radiation became the dominant loss mechanism (∼ 30 min). We aim
to study the flare cooling process using high resolution observations
from Hinode/EIS.

---------------------------------------------------------
Title: Coronal Hole Identification and Characterisation Using
Automated Image Processing Techniques
Authors: Krista, L. D.; Gallagher, P. T.
2008ASPC..397..176K Altcode:
We investigate the properties of coronal holes using a histogram-based
intensity thresholding technique. The area and the coordinates of the
centroid were determined for a coronal hole observed by SOHO/EIT and
Hinode/XRT on 20-26 May 2007. This hole was also associated with a
significant increase in the mean solar wind speed measured by ACE at L1.

---------------------------------------------------------
Title: Multiscale Characterization of Eruptive Events
Authors: Byrne, J. P.; Young, C. A.; Gallagher, P. T.; McAteer,
R. T. J.
2008ASPC..397..162B Altcode:
Image processing plays an important role in the analysis of data
from space-based instruments. With the large volumes of information
currently available from missions such as Hinode and STEREO, our aim
is to produce computationally fast methods for extracting features of
interest (e.g. loops, filaments, waves and eruptions). Multiscale image
processing methods enable us to study these features as a function
of scale. Here we describe these methods, and use them to study the
multiscale properties of a coronal mass ejection (CME) observed by
SOHO/LASCO, and briefly discuss the implications for Hinode.

---------------------------------------------------------
Title: The Kinematics of a Globally Propagating Disturbance in the
Solar Corona
Authors: Long, David M.; Gallagher, Peter T.; McAteer, R. T. James;
Bloomfield, D. Shaun
2008ApJ...680L..81L Altcode: 2008arXiv0805.2023L
The kinematics of a globally propagating disturbance (also known as
an "EIT wave") is discussed using Extreme UltraViolet Imager (EUVI)
data from the Solar Terrestrial Relations Observatory (STEREO). We
show for the first time that an impulsively generated propagating
disturbance has similar kinematics in all four EUVI passbands (304,
171, 195, and 284 Å). In the 304 Å passband the disturbance shows a
velocity peak of 238 ± 20 km s-1 within ~28 minutes of its
launch, varying in acceleration from 76 to -102 m s-2. This
passband contains a strong contribution from a Si XI line (303.32 Å)
with a peak formation temperature of ~1.6 MK. The 304 Å emission may
therefore be coronal rather than chromospheric in origin. Comparable
velocities and accelerations are found in the coronal 195 Å passband,
while lower values are found in the lower cadence 284 Å passband. In
the higher cadence 171 Å passband the velocity varies significantly,
peaking at 475 ± 47 km s-1 within ~20 minutes of launch,
with a variation in acceleration from 816 to -413 m s-2. The
high image cadence of the 171 Å passband (2.5 minutes compared to 10
minutes for the similar temperature response 195 Å passband) is found
to have a major effect on the measured velocity and acceleration of
the pulse, which increase by factors of ~2 and ~10, respectively. This
implies that previously measured values (e.g., using EIT) may have
been underestimated. We also note that the disturbance shows strong
reflection from a coronal hole in both the 171 and 195 Å passbands. The
observations are consistent with an impulsively generated fast-mode
magnetoacoustic wave.

---------------------------------------------------------
Title: Automated Detection and Characterisation of Coronal Holes
Authors: Krista, L. D.; Gallagher, P. T.
2008AGUSMSP51A..13K Altcode:
We investigate the physical properties of coronal holes using a
histogram-based intensity thresholding technique. The method was
tested on coronal holes observed by the SOHO/EIT and the Hinode/XRT
instruments. The full-disk images were first transformed using the
Carrington projection, which has the effect of removing off-limb pixels
and preserving coronal hole areas at high latitudes. The maps were
then decomposed into a series of overlapping sub-images from which
histograms were extracted. The sub-images containing only quiet-sun
regions showed a unimodal distribution, while those containing part
of a coronal hole as well as quite Sun regions had bimodal intensity
distributions. The latter distributions were modelled as the sum of
two frequency distributions, representing contributions from quiet-sun
and coronal hole pixels. The local minimum between the two intensity
distributions was then used to identify the boundary between coronal
hole and quiet-sun regions. This model was tested on a large number of
EIT (19.5nm) and Hinode/XRT images obtained in Jan-Feb 2008. For both
instruments, the local thresholding algorithm was found to successfully
determine coronal hole boundaries in a consistent manner. This therefore
enabled us to investigate the relationship between coronal holes and
the solar wind at 1AU during this sample period.

---------------------------------------------------------
Title: Multi-scale structure of active region magnetic fields
correlated with flaring activity
Authors: Ireland, J.; Young, C. A.; McAteer, R. J.; Whelan, C. M.;
Hewett, R.; Gallagher, P. T.
2008AGUSMSH43B..03I Altcode:
Two multi-scale analyses are used to decompose active region magnetic
fields into objects of different size scales, allowing one to examine
the structure of the active region field at different size scales. Lines
separating opposite polarity groupings of flux at different size scales
are found. It is shown that the magnetic field gradients for α,
β, βγ, and βγδ active regions increases in the order listed,
and that the order is maintained over all object size scales. Hence
for a given Mt. Wilson classification, essentially the same field
gradient information is present at all size scales, when compared to
any other Mt. Wilson classification. It is also shown that on average,
flaring and non-flaring active regions have a different field gradient
content, and that the difference between the flaring and non-flaring
active regions is size scale dependent. This suggests that the gradient
distribution on smaller size scales is a better indicator of flaring
activity when compared to larger size scales.

---------------------------------------------------------
Title: Hydrodynamics of Cooling Solar Flare Plasmas
Authors: Raftery, C. L.; Gallagher, P. T.; Milligan, R. O.
2008AGUSMSP51C..17R Altcode:
The temperature and emission measure evolution of a cooling post-flare
arcade are investigated using images and spectra from the Reuven Ramaty
High Energy Solar Spectroscopic Imager (RHESSI). This C-class flare,
observed on 2006 December 17, occurred on the west limb and lasted
approximately 8-hours. It is therefore ideally suited for studying how
the temperature and emission measure change during a flare. Observable
parameters such as temperature and emission measure are compared to
theoretical hydrodynamic models to constrain parameters such as the
direct and non-thermal heating. Comparing these results to those of a
flare with decay time of approximately 1-hour highlights the energies
required to sustain such a long duration event. The high time resolution
of RHESSI combined with the long duration of the observations are
ideal for making a detailed comparison with the predictions of theory.

---------------------------------------------------------
Title: Multiscale Analysis of Active Region Evolution
Authors: Hewett, R. J.; Gallagher, P. T.; McAteer, R. T. J.; Young,
C. A.; Ireland, J.; Conlon, P. A.; Maguire, K.
2008SoPh..248..311H Altcode:
Flows in the photosphere of solar active regions are turbulent in
nature. Because magnetic fields are frozen into the plasma on the
solar surface, magnetograms can be used to investigate the processes
responsible for structuring active regions. Here, a continuous wavelet
technique is developed, analyzed, and used to investigate the multiscale
structure of an evolving active region using magnetograms obtained by
the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric
Observatory (SOHO). The multiscale structure was measured using a 2D
continuous wavelet technique to extract the energy spectrum of the
region over the time scale of 13 days. Preliminary evidence of an
inverse cascade in active region NOAA 10488 is presented as well as
a potential relationship between energy scaling and flare productivity.

---------------------------------------------------------
Title: Multiscale Edge Detection in the Corona
Authors: Young, C. Alex; Gallagher, Peter T.
2008SoPh..248..457Y Altcode: 2008SoPh..tmp...76Y; 2008arXiv0804.1964Y
Coronal Mass Ejections (CMEs) are challenging objects to detect using
automated techniques, due to their high velocity and diffuse, irregular
morphology. A necessary step to automating the detection process is
to first remove the subjectivity introduced by the observer used in
the current, standard, CME detection and tracking method. Here we
describe and demonstrate a multiscale edge detection technique that
addresses this step and could serve as one part of an automated CME
detection system. This method provides a way to objectively define a
CME front with associated error estimates. These fronts can then be
used to extract CME morphology and kinematics. We apply this technique
to a CME observed on 18 April 2000 by the Large Angle Solar COronagraph
experiment (LASCO) C2/C3 and a CME observed on 21 April 2002 by LASCO
C2/C3 and the Transition Region and Coronal Explorer (TRACE). For the
two examples in this work, the heights determined by the standard
manual method are larger than those determined with the multiscale
method by ≈10% using LASCO data and ≈20% using TRACE data.

---------------------------------------------------------
Title: Multifractal Properties of Evolving Active Regions
Authors: Conlon, P. A.; Gallagher, P. T.; McAteer, R. T. J.; Ireland,
J.; Young, C. A.; Kestener, P.; Hewett, R. J.; Maguire, K.
2008SoPh..248..297C Altcode:
Magnetohydrodynamic turbulence is thought to be responsible for
producing complex, multiscale magnetic field distributions in solar
active regions. Here we explore the multiscale properties of a number of
evolving active regions using magnetograms from the Michelson Doppler
Imager (MDI) on the Solar and Heliospheric Observatory (SOHO). The
multifractal spectrum was obtained by using a modified box-counting
method to study the relationship between magnetic-field multifractality
and region evolution and activity. The initial emergence of each
active region was found to be accompanied by characteristic changes
in the multifractal spectrum. Specifically, the range of multifractal
structures (Ddiv) was found to increase during emergence,
as was their significance or support (Cdiv). Following this,
a decrease in the range in multifractal structures occurred as the
regions evolved to become large-scale, coherent structures. From the
small sample considered, evidence was found for a direct relationship
between the multifractal properties of the flaring regions and their
flaring rate.

---------------------------------------------------------
Title: Correlation of multi-resolution analyses of active region
magnetic field structure with flare activity
Authors: Ireland, J.; Young, A.; McAteer, J.; Whelan, C.; Hewett,
R. J.; Gallagher, P. T.
2007AGUFMSH13A1094I Altcode:
Two multi-resolution analyses are used to decompose active region
magnetic fields into objects of different lengthscales, allowing
one to examine the structure of the active region field at different
lengthscales. Lines separating opposite polarity groupings of flux
at different lengthscales are found (a generalization of the notion
of a magnetic neutral line). It is shown that the average magnetic
field gradient for alpha, beta, beta-gamma, and beta-gamma-delta
active regions increases in the order listed, and that the order is
maintained over all length-scales. Since magnetic field gradient is
strongly linked to active region activity, such as flares, this study
demonstrates that, on average, the Mt. Wilson classification encodes
the notion of activity over all lengthscales in the active region, and
not just those lengthscales at which the strongest field gradients are
found. Properties of these generalized neutral lines are also correlated
with GOES flare activity in a search for an indicator of flare activity.

---------------------------------------------------------
Title: Multi-scale Tools for Solar Image Processing
Authors: Young, C.; Ireland, J.; McAteer, R.; Gallagher, P. T.;
Byrne, J.
2007AGUFMSH13A1093Y Altcode:
The important information contained in solar image data exists on many
different time and spatial scales. This makes multi-scale transforms
such as wavelets and curvelets very appropriate tools. These and other
multi- scale transforms are used in several different types of image
processing including image enhancement, feature detection, deconvolution
and noise reduction. We present an overview of multi-scale transforms
and show some of their applications to solar image data.

---------------------------------------------------------
Title: The Bursty Nature of Solar Flare X-Ray Emission
Authors: McAteer, R. T. James; Young, C. Alex; Ireland, Jack;
Gallagher, Peter T.
2007ApJ...662..691M Altcode:
The complex and highly varying temporal nature of emission from an X4.8
flare is studied across seven X-ray energy bands. A wavelet transform
modulus maxima method is used to obtain the multifractal spectra of
the temporal variation of the X-ray emission. As expected from the
Neupert effect, the time series of the emission at low energies (3-6,
6-12 keV; thermal) is smooth. The peak Hölder exponent, around 1.2,
for this low-energy emission is indicative of a signal with a high
degree of memory and suggestive of a smooth chromospheric evaporation
process. The more bursty emission at higher energies (100-300, 300-800
keV; nonthermal) is described by a multifractal spectrum that peaks at a
smaller Hölder exponent (less than 0.5 for the largest singularities),
indicative of a signal with a low degree of memory. This describes an
antipersistent walk and indicates an impulsive, incoherent driving
source. We suggest that this may arise from bursty reconnection,
with each reconnection event producing a different and uncorrelated
nonthermal particle source. The existence of a power-law scaling
of wavelet coefficients across timescales is in agreement with the
creation of a fractal current sheet diffusion region.

---------------------------------------------------------
Title: Wavelet Analysis of Active Region Magnetic Structure
Authors: Ireland, Jack; Young, C. A.; Gallagher, P. T.; McAteer,
R. T. James; Whelan, C.; Hewett, R. J.
2007AAS...210.9322I Altcode: 2007BAAS...39..214I
A wavelet analysis is used to decompose active region magnetic
fields into regions of different lengthscales, allowing one to
examine the structure of the active region field at different
lengthscales. Linesseparating opposite polarity groupings of flux
at different lengthscales are found; these lines can be seen as a
generalization of the notion of a magnetic neutral line. It is shown
that the average magnetic field gradient for alpha, beta, beta-gamma,
and beta-gamma-delta active regions increases in the order listed,
and that the order is maintained over all length-scales. Further,
the standard deviation and maximum of the magnetic field gradient,
as well as the length of these generalized neutral lines, all share
the same property. Since magnetic field gradient is strongly linked
to active region activity, such as flares, this study demonstrates
that, on average, the Mt. Wilson classification encodes the notion
of activity over all lengthscales in the active region, and not
just those lengthscales at which the strongest field gradients are
found. This study uses the multiscale analysis toolkit Mkit developed
by C. A. Young and presented elsewhere at this meeting.

---------------------------------------------------------
Title: Solar Activity Monitoring
Authors: Gallagher, Peter T.; McAteer, R. T. James; Young, C. Alex;
Ireland, Jack; Hewett, Russell J.; Conlon, Paul
2007ASSL..344...15G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Multiscale Solar Image Processing
Authors: Young, C. B.; Byrne, J.; Ireland, J.; Gallagher, P. T.;
McAteer, R. J.
2006AGUFMSH23B0369Y Altcode:
Wavelets have been very successfully used as a tool for noise reduction
and general processing of images. Despite this, wavelets have inherent
limitations with 2-D data. Wavelets are well suited for describing
point singularities but much of the interesting information in images
is described by edges, lines or curves. Newly developed multiscale
transforms address some of these issues. The ridgelet transform takes
the multiscale concept of wavelets but applies it to 1-D objects (lines)
instead of 0-D objects (points). The curvelet transform likewise
applies to multiscale curves. We present a preliminary study of the
use of these new multiscale transforms with solar image data. These
data include TRACE EUV images and LASCO coronagraph images.

---------------------------------------------------------
Title: The Complex Sun: Turbulence and Complexity of the Solar
atmosphere
Authors: McAteer, R. T. James; Gallagher, Peter T.; Ireland, J.;
Young, C Alex; Hewett, Russell J.; Conlon, P.
2006ESASP.617E.137M Altcode: 2006soho...17E.137M
No abstract at ADS

---------------------------------------------------------
Title: Observational Evidence of Gentle and Explosive Chromospheric
Evaporation
Authors: Milligan, R. O.; Gallagher, P. T.; Mathioudakis, M.; Keenan,
F. P.
2006ESASP.617E.138M Altcode: 2006soho...17E.138M
No abstract at ADS

---------------------------------------------------------
Title: Observational Evidence of Chromospheric Evaporation
Authors: Milligan, Ryan O.; Gallagher, P. T.; Mathioudakis, M.;
Keenan, F. P.
2006SPD....37.0828M Altcode: 2006BAAS...38R.662M
Observational evidence for chromospheric evaporation during the
impulsive phase of two solar flares is presented using data from the
Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and the
Coronal Diagnostic Spectrometer (CDS) on board SOHO. For the first
time, co-spatial imaging and spectroscopy have been used to observe
both gentle and explosive evaporation processes within HXR emitting
regions. For a GOES C9.1 flare, a low flux of non-thermal electrons
was found to produce low-velocity upflows in the cool He I and O V
emission lines and moderate upflows in the 8 MK Fe XIX line indicative
of gentle evaporation. An M2.2 flare, on the other hand, showed
low-velocity downflows in the He I and O V lines and high-velocity
upflows in the Fe XIX line, for an electron flux value which was an
order of magnitude higher, indicative of an explosive process. These
findings confirm that the dynamic response of the solar atmosphere is
sensitively dependent on the flux of incident electrons as predicted
by current hydrodynamical simulations.

---------------------------------------------------------
Title: How Complex Are Solar Flare Hrx Lightcurves? A Multiscalar
Multifractal Approach.
Authors: McAteer, R. T. J.; Young, C.; Ireland, J.; Gallagher, P. T.
2006SPD....37.0824M Altcode: 2006BAAS...38..235M
A wavelet transform modulus maxima approach to the calculation of
the singularity spectrum is applied to hard X-ray (7 energy bands
from 3--800keV) lightcurves from an X4.8 flare on 23 July 2002. The
multifractality of each lightcurve is discussed in terms of the
Hausdorff dimension, D, of the Holder exponent, h, of each detected
singularity. In addition to a general discussion of the technique, we
show results showing a general increase in complexity of lightcurves
at higher energies

---------------------------------------------------------
Title: Multiscale Structure of Active Region Magnetic Fields
Authors: Hewett, Russell J.; Gallagher, P. T.; McAteer, R.; Young,
C.; Ireland, J.
2006SPD....37.0301H Altcode: 2006BAAS...38..222H
Flows in the photosphere of solar active regions are in a state ofhighly
developed turbulence. As magnetic fields are frozen into theplasma in
the solar surface, magnetograms can therefore be used toinvestigate
the processes responsible for structuring active regions.Here, the
multiscale structure of a large sample of active regionmagnetograms from
the Michelson Doppler Imager (MDI) onboard theSolar and Heliospheric
Observatory (SOHO) are investigated. Initialresults regarding the
relationship between multiscale structuring andactive region evolution
and flaring activity is discussed.

---------------------------------------------------------
Title: Multifractal Analysis of Solar Magnetograms
Authors: Conlon, Paul; McAteer, R. T.; Gallagher, P. T.; Ireland,
J.; Young, C. A.; Young, C. A.
2006SPD....37.0303C Altcode: 2006BAAS...38Q.222C
Magnetohydrodynamic turbulence is thought to be responsible for
structuring sunspot magnetic fields. Here we explore the selfsimilar
and multi-scaling properties of this turbulence using multi-fractal
methods. The multi-fractal spectrum was obtained from full disk
Michelos Doppler Imager magnetograms, to study the relationship
between magnetic field multifractality and flaring and non-flaring
regions. In particular, box counting and wavelet based techniques
where investigated. The discrete box counting method was found to
be inadequate for these purposes, primarily due to discretization
errors. Wavelet based methods, on the other hand, where found to be
more stable for diagnosing turbulence in active region magnetic fields.

---------------------------------------------------------
Title: Observational Evidence of Gentle Chromospheric Evaporation
during the Impulsive Phase of a Solar Flare
Authors: Milligan, Ryan O.; Gallagher, Peter T.; Mathioudakis, Mihalis;
Keenan, Francis P.
2006ApJ...642L.169M Altcode: 2006astro.ph..3652M
Observational evidence of gentle chromospheric evaporation during
the impulsive phase of a C9.1 solar flare is presented using data
from the Reuven Ramaty High-Energy Solar Spectroscopic Imager and the
Coronal Diagnostic Spectrometer on board the Solar and Heliospheric
Observatory. Until now, evidence of gentle evaporation has often
been reported during the decay phase of solar flares, where thermal
conduction is thought to be the driving mechanism. Here we show that
the chromospheric response to a low flux of nonthermal electrons
(&gt;=5×109 ergs cm-2 s-1) results
in plasma upflows of 13+/-16, 16+/-18, and 110+/-58 km s-1
in the cool He I and O V emission lines and the 8 MK Fe XIX line,
respectively. These findings, in conjunction with other recently
reported work, now confirm that the dynamic response of the solar
atmosphere is sensitively dependent on the flux of incident electrons.

---------------------------------------------------------
Title: RHESSI and SOHO CDS Observations of Explosive Chromospheric
Evaporation
Authors: Milligan, Ryan O.; Gallagher, Peter T.; Mathioudakis, Mihalis;
Bloomfield, D. Shaun; Keenan, Francis P.; Schwartz, Richard A.
2006ApJ...638L.117M Altcode: 2005astro.ph..9664M
Simultaneous observations of explosive chromospheric evaporation
are presented using data from the Reuven Ramaty High-Energy Solar
Spectroscopic Imager (RHESSI) and the Coronal Diagnostic Spectrometer
(CDS) on board the Solar and Heliospheric Observatory. For the first
time, cospatial imaging and spectroscopy have been used to observe
explosive evaporation within a hard X-ray emitting region. RHESSI
X-ray images and spectra were used to determine the flux of nonthermal
electrons accelerated during the impulsive phase of an M2.2 flare. When
we assumed a thick-target model, the injected electron spectrum was
found to have a spectral index of ~7.3, a low-energy cutoff of ~20 keV,
and a resulting flux of &gt;=4×1010 ergs cm-2
s-1. The dynamic response of the atmosphere was determined
using CDS spectra; we found a mean upflow velocity of 230+/-38 km
s-1 in Fe XIX (592.23 Å) and associated downflows of
36+/-16 and 43+/-22 km s-1 at chromospheric and transition
region temperatures, respectively, relative to an averaged quiet-Sun
spectra. The errors represent a 1 σ dispersion. The properties of
the accelerated electron spectrum and the corresponding evaporative
velocities were found to be consistent with the predictions of theory.

---------------------------------------------------------
Title: Wavelet analysis of Active Region structure
Authors: Ireland, J.; Young, C. A.; Whelan, C.; Gallagher, P. T.;
McAteer, R. T. J.; Hewett, R. J.
2006cosp...36.2595I Altcode: 2006cosp.meet.2595I
Active regions are known to consist of complex magnetic fields as
evinced by both fractal and multifractal studies In contrast the Mt
Wilson classification of active regions is relatively simple yet is
useful in predicting the likelihood of flaring events since it considers
the overall geometrical structure of the active region In particular
neutral lines are especially important in evaluating the likelihood
of flare events occurring Wavelet analysis techniques in conjunction
with edge detection methods are applied to the problem of diagnosing
the gross geometrical structure of active region magnetic field Active
region fields are decomposed into their constituent parts using wavelet
techniques and edge detection methods are used to characterize the
neutral lines present A statistical analysis is presented outlining
the utility of this approach in automatically generating a Mt Wilson
classification for a given active region

---------------------------------------------------------
Title: Plasma diagnostics of active-region evolution and implications
for coronal heating
Authors: Milligan, R. O.; Gallagher, P. T.; Mathioudakis, M.; Keenan,
F. P.; Bloomfield, D. S.
2005MNRAS.363..259M Altcode: 2005MNRAS.tmp..764M; 2005astro.ph..9219M
A detailed study is presented of the decaying solar-active region NOAA
10103 observed with the Coronal Diagnostic Spectrometer (CDS), the
Michelson Doppler Imager (MDI) and the Extreme-ultraviolet Imaging
Telescope (EIT) onboard the Solar and Heliospheric Observatory
(SOHO). Electron-density maps formed using SiX (356.03 Å/347.41 Å)
show that the density varies from ~1010cm-3
in the active-region core to ~7 × 108cm-3
at the region boundaries. Over the 5d of observations, the average
electron density fell by ~30 per cent. Temperature maps formed using
FeXVI (335.41 Å)/FeXIV (334.18 Å) show electron temperatures of
~2.34 × 106 K in the active-region core and ~2.10 ×
106 K at the region boundaries. Similarly to the electron
density, there was a small decrease in the average electron temperature
over the 5-d period. The radiative, conductive and mass-flow losses
were calculated and used to determine the resultant heating rate
(PH). Radiative losses were found to dominate the
active-region cooling process. As the region decayed, the heating
rate decreased by almost a factor of 5 between the first and last
day of observations. The heating rate was then compared to the
total unsigned magnetic flux , yielding a power law of the form
PH~Φ0.81+/-0.32tot. This result
suggests that waves rather than nanoflares may be the dominant heating
mechanism in this active region.

---------------------------------------------------------
Title: Statistics of Active Region Complexity: A Large-Scale Fractal
Dimension Survey
Authors: McAteer, R. T. James; Gallagher, Peter T.; Ireland, Jack
2005ApJ...631..628M Altcode:
A quantification of the magnetic complexity of active regions using a
fractal dimension measure is presented. This fully automated approach
uses full-disk MDI magnetograms of active regions from a large data set
(2742 days of the SOHO mission, 9342 active region images) to compare
the calculated fractal dimension of each region to both its Mount
Wilson classification and flare rate. Each Mount Wilson class exhibits
a similar fractal dimension frequency distribution, possibly suggesting
a self-similar nature of all active regions. Solar flare productivity
exhibits an increase in both the frequency and GOES X-ray magnitude
of flares from regions with higher fractal dimension. Specifically, a
lower threshold fractal dimension of 1.2 and 1.25 exists as a necessary,
but not sufficient, requirement for an active region to produce M-
and X-class flares, respectively, within 24 hr of the observation.

---------------------------------------------------------
Title: Foreword
Authors: Gallagher, Peter; Berghmans, David; Aschwanden, Markus
2005SoPh..228....1G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Automated Boundary-extraction And Region-growing Techniques
Applied To Solar Magnetograms
Authors: McAteer, R. T. James; Gallagher, Peter T.; Ireland, Jack;
Young, C. Alex
2005SoPh..228...55M Altcode:
We present an automated approach to active region extraction from
full-disc MDI longitudinal magnetograms. This uses a region-growing
technique in conjunction with boundary-extraction to define a number
of enclosed contours as belonging to separate regions of magnetic
significance on the solar disc. This provides an objective definition
of active regions and areas of plage on the Sun. A number of parameters
relating to the flare potential of each region are discussed.

---------------------------------------------------------
Title: Chromospheric Response to Non-Thermal Electrons During Flares
Using RHESSI and SOHO/CDS
Authors: Milligan, R. O.; Gallagher, P. T.; Mathioudakis, M.; Keenan,
F. P.
2005AGUSMSP52A..04M Altcode:
Many current solar flare models predict a relationship between the
amount of energy deposited in the chromospheric and transition region
layers of the solar atmosphere by non-thermal electrons, and the
velocity at which this superheated material rises. For the first time,
we present findings from simultaneous observations of loop footpoints
using RHESSI and SOHO/CDS. RHESSI HXR images and spectra are used to
determine the flux of non-thermal electrons using the thick-target
bremsstrahlung model, while upflow velocities in the Fe XIX emission
line are observed using CDS.

---------------------------------------------------------
Title: From Raw Data to Flare Predictions: A Fully Automated Technique
Authors: McAteer, R. T.; Gallagher, P. T.; Ireland, J.; Young, A.
2005AGUSMSP42A..06M Altcode:
With the large volume of solar data which already exists, and expected
in the near future with SDO, automated techniques are becoming
increasingly vital. We present a fully automated active region
extraction routine based on boundary extraction and region growing
techniques applied to full disc MDI longitudinal magnetograms. Once
extracted, any number of image processing techniques can be applied to
the data leading to the possibility of automated classification. We
discuss a large scale (9 years of MDI data, ~10,000 active region
images) fractal survey of this data. This quantifies the meaning of
magnetic complexity, relating lower threshold fractal dimension to
the onset of large flares.

---------------------------------------------------------
Title: Representation of Sun Spots with Shapelets
Authors: Young, C.; Gallagher, P. T.; Ireland, J.; McAteer, R.
2005AGUSMSP11A..07Y Altcode:
Shapelets are complete set of orthonormal functions that can be used to
represent most images. These functions are Gauss-Hermite polynomials and
are the eigenfunctions of the 2D harmonic oscillator. They were first
used in image processing to study the shape of galaxies. Shapelets have
properties that allow one to compute quantities such as chirality,
shear and asymmetry in images. We use these functions to represent
magnetograms of sunspots, allowing us to calculate a large set of
descriptive quantities including those previously mentioned. These
quantities are then correlated with the current classification schemes
used to type sunspots.

---------------------------------------------------------
Title: Observations of Hα Intensity Oscillations in a Flare Ribbon
Authors: McAteer, R. T. James; Gallagher, Peter T.; Brown, Daniel S.;
Bloomfield, D. Shaun; Moore, Ruth; Williams, David R.; Mathioudakis,
Mihalis; Katsiyannis, A.; Keenan, Francis P.
2005ApJ...620.1101M Altcode:
High-cadence Hα blue wing observations of a C9.6 solar flare
obtained at Big Bear Solar Observatory using the Rapid Dual Imager
are presented. Wavelet and time-distance methods were used to study
oscillatory power along the ribbon, finding periods of 40-80 s during
the impulsive phase of the flare. A parametric study found statistically
significant intensity oscillations with amplitudes of 3% of the peak
flare amplitude, periods of 69 s (14.5 mHz) and oscillation decay times
of 500 s. These measured properties are consistent with the existence
of flare-induced acoustic waves within the overlying loops.

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

---------------------------------------------------------
Title: Active Region Evolution and Activity During the Storms of
Halloween 2003
Authors: Gallagher, P. T.
2004AAS...204.4702G Altcode: 2004BAAS...36..737G
The three week period around Halloween 2003 was characterized by some of
the largest and most energetic flares and CMEs observed in recent years
(e.g., see http://beauty.nascom.nasa.gov/ ptg/oct-nov-2003-xflares.html
for details of the 12 X-class flares). This increased activity resulted
from the almost simultaneous formation of three complex beta-gamma-delta
regions: NOAA 0484, 0486, and 0488. In this talk, the distinctive
characteristics, rapid evolution, and extreme activity of the these
regions will be reviewed in light of the multitude of observations
from SOHO, RHESSI, TRACE, BBSO, and other ground- and space-based
observatories. Our current understanding of the mechanisms involved
in forming such regions, and the processes involved in storing and
releasing such numerous and energetic events will also be discussed.

---------------------------------------------------------
Title: Optical Observations of Flare-Induced Oscillations
Authors: McATeer, R. T. J.; Gallagher, P. T.; Brown, D. S.
2004AAS...204.9806M Altcode: 2004BAAS...36..985M
We present high-cadence H alpha blue wing observations of a C9.6
solar flare. Oscillations (period 40-80s) are shown to be present
in the post-flare section of lightcurves from a short-lived flare
ribbon. Wavelet analysis is used to show the excellent agreement of
oscillatory power at 52.4s with a distance-time plot along one half of
the ribbon. A best-fit of an oscillation to the curve shows oscillatory
amplitude ∼ 0.03% flare ampltiude, period ∼ 69s and decay time
∼ 500s. These parameters are in good agreement with the formation
of a second harmonic acoustic wave. A study of loop lengths along the
ribbon also agrees with the presence of a ∼ 50s period JMA is
funded by a NRC Research Associateship. Observations were carried out
via a Leverhulme Trust Fellowship.

---------------------------------------------------------
Title: Plasma Diagnostics of Active Region Evolution and Implications
for Coronal Heating
Authors: Milligan, R. O.; Gallagher, P. T.; Mathioudakis, M.;
Bloomfield, D. S.; Keenan, F. P.
2004AAS...204.9803M Altcode: 2004BAAS...36..984M
The decaying solar active region NOAA 10103 was observed during 2002
September 10--14 using the Coronal Diagnostic Spectrometer (CDS) onboard
the Solar and Heliospheric Observatory (SOHO). Electron density maps
were created using the Si X (356Å/347Å) ratio, which show densities
of ∼1010cm-3 in the active region core, and
∼7x108cm-3 in the region boundaries. Over
the five days of observations, the average electron density fell by
approximately a factor of two. Temperature maps were created using
the Fe XVI (335.4Å)/Fe XIV (334.2Å) ratio, which show electron
temperatures of ∼2.2x106K in the active region core,
and ∼2.0x106K in the region boundaries. Similarly to the
electron density, the average electron temperature decreased over the
five days, but by only ∼3%. The radiative and conductive losses, and
resultant heating rate, were then calculated and compared to the total
unsigned magnetic flux (Φ tot = ∫ dA |Bz|)
from Michelson Doppler Interferometer (MDI) magnetograms. Losses due to
radiation were found to exceed conductive losses by a factor of ten. As
the region decayed, the heating rate decreased by close to an order of
magnitiude between the first and last day of observations. In line with
several coronal heating theories, a power-law relationship of the form
Ptot} ∼Φ {tot0.95±0.07 was found
between the heating rate and the unsigned magnetic flux. This result
provides further observational evidence for wave rather than nanoflare
heating of solar active regions. Ryan Milligan would like to
thank the Solar Physics Division for being awarded an SPD Studentship.

---------------------------------------------------------
Title: Search for 1-10 Hz modulations in coronal emission with SECIS
during the August 11, 1999 eclipse
Authors: Rudawy, P.; Phillips, K. J. H.; Gallagher, P. T.; Williams,
D. R.; Rompolt, B.; Keenan, F. P.
2004A&A...416.1179R Altcode:
Results of the search of the periodic changes of the 530.3 nm line
intensity emitted by selected structures of the solar corona in the
frequency range 1-10 Hz are presented. A set of 12 728 images of the
section of the solar corona extending from near the north pole to
the south-west were taken simultaneously in the 530.3 nm (“green”)
line and white-light with the Solar Eclipse Coronal Imaging System
(SECIS) during the 143-seconds-long totality of the 1999 August
11 solar eclipse observed in Shabla, Bulgaria. The time resolution
of the collected data is better than 0.05 s and the pixel size is
approximately 4 arcsec. Using classical Fourier spectral analysis tools,
we investigated temporal changes of the local 530.3 nm coronal line
brightness in the frequency range 1-10 Hz of thousands of points within
the field of view. The various photometric and instrumental effects
have been extensively considered. We did not find any indisputable,
statistically significant evidence of periodicities in any of the
investigated points (at significance level α=0.05).

---------------------------------------------------------
Title: Ultraviolet Oscillations in the Chromosphere of the Quiet Sun
Authors: McAteer, R. T. James; Gallagher, Peter T.; Bloomfield,
D. Shaun; Williams, David R.; Mathioudakis, Mihalis; Keenan, Francis P.
2004ApJ...602..436M Altcode:
Quiet-Sun oscillations in the four Transition Region and Coronal
Explorer (TRACE) ultraviolet passbands centered on 1700, 1600,
1216, and 1550 Å are studied using a wavelet-based technique. Both
network and internetwork regions show oscillations with a variety of
periods and lifetimes in all passbands. The most frequent network
oscillation has a period of 283 s, with a lifetime of 2-3 cycles
in all passbands. These oscillations are discussed in terms of
upwardly propagating magnetohydrodynamic wave models. The most
frequent internetwork oscillation has a period of 252 s, again with
a lifetime of 2-3 cycles, in all passbands. The tendency for these
oscillations to recur in the same position is discussed in terms of
“persistent flashers.” The network contains greater oscillatory
power than the internetwork at periods longer than 300 s in the
low chromosphere. This value is shown to decrease to 250 s in the
high chromosphere. The internetwork also displays a larger number of
short-lifetime, long-period oscillations than the network, especially
in the low chromosphere. Both network and internetwork regions contain
a small number of nonrecurring long-lifetime oscillations.

---------------------------------------------------------
Title: An Automated Wavelet Analysis Approach to TRACE Quiet Sun
Oscillations
Authors: McAteer, R. T. J.; Gallagher, P. T.; Williams, D. R. Williams
D. R.; Bloomfield, D. S.; Mathioudakis, M.; Keenan, F. P.
2004ESASP.547..139M Altcode: 2004soho...13..139M
An automated wavelet analysis approach to TRACE UV quiet Sun datasets
is discussed. Periodicity and lifetime of oscillations present in the
network and internetwork are compared and contrasted. This provides
a means of extending previous Fourier results into the time-localised
domain. The longest lifetime oscillations occur around the acoustic band
and the network tends to dominate over the internetwork at periods 4
mins. However, it is shown that the internetwork can dominate over the
network at long periods (7 - 20 mins), but only for short lifetimes
( 3 complete oscillations). These results are discussed in terms of
chromospheric heating theories.

---------------------------------------------------------
Title: Physics of superfast coronal mass ejections observed during
cycle 23
Authors: Lawrence, G.; Gallagher, P.; Leamon, R.; Stenborg, G.
2004cosp...35.2882L Altcode: 2004cosp.meet.2882L
Between January 1996 and the present time the Large Angle Spectrometric
Coronagraphs (LASCO) onboard the Solar and Heliospheric Observatory
(SOHO) have observed over 6000 coronal mass ejections (CMEs). The
typical speed of these CMEs has been found to vary between 400-500 km/s
during the present solar cycle, and the vast majority of all CMEs are
found to have speeds below 1,000 km/s. However, a high-speed tail to
the distribution is clearly present, and a small fraction of all CMEs,
20 events in total, are found to have speeds in the range 2,000 - 2,500
km/s. This category of 'superfast CMEs' is doubly significant because
they appear to correspond the extreme limits of physics involved in the
initiation and acceleration processes, and because such events when
directed earthwards have characteristically short transit times and
hence leave little reaction/assessment time for potentially sensitive
systems. The superfast CMEs are all associated with significant solar
flares, and the large flare/very fast CME paradigm is studied. Of
particular interest is the acceleration of such very fast CMEs and
the nature, magnitude and timing of the acceleration process is
characterised within the limits of the observations.

---------------------------------------------------------
Title: Initial Results from SECIS Observations of the 2001 Eclipse
Authors: Katsiyannis, A. C.; McAteer, R. T. J.; Williams, D. R.;
Gallagher, P. T.; Keenan, F. P.
2004ESASP.547..459K Altcode: 2004astro.ph.11722K; 2004soho...13..459K
SECIS observations of the June 2001 total solar eclipse were taken
using an Fe XIV 5303 Å filter. Existing software was modified and new
code was developed for the reduction and analysis of these data. The
observations, data reduction, study of the atmospheric and instrumental
effects, together with some preliminary results are discussed. Emphasis
is given to the techniques used for the automated alignment of the 8000
images, the application of the `a Trous algorithm for noise filtering
and the software developed for the automated detection of intensity
oscillations using wavelet analysis. In line with findings from the
1999 SECIS total eclipse observations, intensity oscillations with
periods in the range of 20-30 s, both inside and just outside coronal
loops are also presented.

---------------------------------------------------------
Title: The Relationship Between Large Solar Flares and Very Fast
Coronal Mass Ejections - Physics and Causality
Authors: Lawrence, G.; Gallagher, P.; Dennis, B.
2003AGUFMSH21C..07L Altcode:
The fastest coronal mass ejection observed to date by the LASCO
coronagrph onboard SOHO was also the best observed thanks to the Max
Millenium co-ordinated observation campaign running at the time. Data
from RHESSI, TRACE and SOHO from April 21 2002 are presented which
yield a clear timeline of the physical processes involved and their
relationships to each other. The causality of the solar flare-CME
system is discussed and implications for theory and modelling are
presented. Other large flare/very fast CME events are analysed and
agreement with the paradigm is studied. Particular attention is paid
to the acceleration of such very fast CMEs and the nature, magnitude
and timing of the acceleration process is characterised within the
limits of the observations.

---------------------------------------------------------
Title: The Polar Crown Filament Eruption and Associated CME of 2003
February 18
Authors: Hill, S. M.; Christopher, B. C.; Burkepile, J.; Gallagher,
P. T.; Detoma, G.
2003AGUFMSH21C..04H Altcode:
On 2003 February 18, a polar crown filament dramatically erupted,
becoming the core of a classic three part Coronal Mass Ejection
(CME). The event was well observed from the disk to 30 solar radii in
multiple bands, some of which were at high cadence. Phenomena observed
include: high-latitude filament eruption, the formation of two bright
ribbons, soft X-ray coronal dimmings, post-eruption arcade evolution,
and a classical three-part CME. Specifically, the filament eruption was
seen on the disk and out to ~1.3 solar radii in soft X-rays, extreme
ultraviolet, H-alpha, and He I 1083 nm. The CME was visible in white
light coronagraph images from 1.08 to 30 solar radii. Though post CME
reconnection arcades reached only the B5 level in GOES XRS measurements,
they were observed in hard X-rays (at energies less than 12 keV),
soft X-rays, extreme ultraviolet, and a two-ribbon flare structure was
seen in H-alpha and in He I 1083 nm. The observations were conducted
using GOES SXI, SOHO EIT and LASCO, RHESSI, and the MLSO ACOS suite. We
present the results of our initial timing, height vs. time, and light
curve analyses of this event. The timing results address issues of
the simultaneity and sequence of filament motion, coronal dimming,
CME 'launch', and arcade formation. The height versus time results are
presented for both the filament/CME core and the CME front to provide
observational constraints for CME acceleration models. Finally,
the arcade light curve results support estimation of the magnetic
reconnection rate for further discrimination between model predictions.

---------------------------------------------------------
Title: Multiscale Feature Identification in the Solar Atmosphere
Authors: Young, C.; Gallagher, P. T.; Myers, D. C.
2003AGUFMSH42B0543Y Altcode:
Multiscale methods offer a powerful approach to solar image processing
and analysis. In this paper, wavelet-based methods are applied to
a sequence of TRACE 195 passband images and LASCO C2/C3 white-light
images to unambiguously identify faint features associated with the
2002 April 21 X-class flare and CME. Morphological properties, such as
feature width, height, velocity and acceleration are then extracted, and
compared to recent results from traditional image processing techniques.

---------------------------------------------------------
Title: Eclipse observations of high-frequency oscillations in active
region coronal loops
Authors: Katsiyannis, A. C.; Williams, D. R.; McAteer, R. T. J.;
Gallagher, P. T.; Keenan, F. P.; Murtagh, F.
2003A&A...406..709K Altcode: 2003astro.ph..5225K
One of the mechanisms proposed for heating the corona above solar active
regions is the damping of magnetohydrodynamic (MHD) waves. Continuing
on previous work, we provide observational evidence for the existence
of high-frequency MHD waves in coronal loops observed during the
August 1999 total solar eclipse. A wavelet analysis is used to identify
twenty 4x4 arcsec2 areas showing intensity oscillations. All
detections lie in the frequency range 0.15-0.25 Hz (7-4 s), last for
at least 3 periods at a confidence level of more than 99% and arise
just outside known coronal loops. This leads us to suggest that they
occur in low emission-measure or different temperature loops associated
with the active region.

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

---------------------------------------------------------
Title: Multiscale Feature Identification in Solar Flares and CMEs
Authors: Myers, D. C.; Gallagher, P. T.; Young, C. A.
2003SPD....34.0307M Altcode: 2003BAAS...35Q.809M
Multiscale methods offer a powerful approach to solar image processing
and analysis. In this paper, wavelet-based methods are applied to a
sequence of TRACE 195 Å passband images to unambiguously identify
faint features associated with the 2002 April 21 X-class flare and
CME. Morphological properties, such as feature width, height, velocity
and acceleration are then extracted, and compared to recent results
from traditional image processing techniques.

---------------------------------------------------------
Title: Rapid Acceleration of a Coronal Mass Ejection in the Low
Corona and Implications for Propagation
Authors: Gallagher, Peter T.; Lawrence, Gareth R.; Dennis, Brian R.
2003ApJ...588L..53G Altcode:
A high-velocity coronal mass ejection (CME) associated with the 2002
April 21 X1.5 flare is studied using a unique set of observations from
the Transition Region and Coronal Explorer (TRACE), the Ultraviolet
Coronagraph Spectrometer (UVCS), and the Large Angle and Spectroscopic
Coronagraph (LASCO). The event is first observed as a rapid rise in
GOES X-rays, followed by two simultaneous brightenings that appear
to be connected by an ascending looplike feature. While expanding,
the appearance of the feature remains remarkably constant as it passes
through the TRACE 195 Å passband and LASCO fields of view, allowing
its height-time behavior to be accurately determined. The acceleration
is consistent with an exponential rise with an e-folding time of ~138
s and peaks at ~1500 m s-2 when the leading edge is at ~1.7
Rsolar from Sun center. The acceleration subsequently falls
off with an e-folding time of over 1000 s. At distances beyond ~3.4
Rsolar, the height-time profile is approximately linear
with a constant velocity of ~2500 km s-1. These results
are briefly discussed in light of recent kinematic models of CMEs.

---------------------------------------------------------
Title: RHESSI, TRACE, and the Spatial Neupert Effect
Authors: Zarro, D. M.; Dennis, B. R.; Gallagher, P.; Tolbert, A. K.;
Myers, D. C.
2003SPD....34.1804Z Altcode: 2003BAAS...35..840Z
We combine RHESSI and TRACE observations to investigate the spatial and
temporal associations between hard X-ray (HXR) and extreme ultraviolet
(EUV) emissions in impulsive bursts observed during the GOES X flare
of April 21, 2002. The RHESSI HXR (above 25 keV) time profile for this
event is in general agreement with the time derivative of the GOES
soft X-ray (1 to 8-A) flux. This temporal correlation - the Neupert
Effect - is consistent with nonthermal thick-target electrons being the
primary source of heating of the soft X-ray emitting thermal plasma
during the flare impulsive phase. To further investigate the
link between nonthermal electrons and thermal soft X-ray emission,
we examine the spatial and temporal behavior of HXR emission in
high-resolution (2-3 arcsecs) RHESSI images. Specifically, we identify
regions of enhanced HXR emission and compare their lightcurves
with corresponding lightcurves observed simultaneously with the
TRACE 195-A filter at 1-arcsec spatial resolution. The TRACE 195-A
bandpass contains contributions from Fe XII and Fe XXIV lines which
are sensitive to plasmas at temperatures of near 1.5 MK and 15-20 MK,
respectively. Consequently, when used in conjunction with GOES, the
TRACE 195-A flux provides a useful proxy for investigating the spatial
properties of flare-heated thermal plasma.

---------------------------------------------------------
Title: Rapid Acceleration of a Coronal Mass Ejection in the Low
Corona and Implications for Propagation
Authors: Gallagher, P.; Lawrence, G.; Dennis, B.
2003SPD....34.0515G Altcode: 2003BAAS...35..816G
A high-velocity Coronal Mass Ejection (CME) associated with the 2002
April 21 X1.5 flare is studied using a unique set of observations from
the Transition Region and Coronal Explorer (TRACE), the Ultraviolet
Coronagraph Spectrometer (UVCS), and the Large-Angle Spectrometric
Coronagraph (LASCO). The event is first observed as a rapid rise in
GOES X-rays, followed by two simultaneous brightenings which appear
to be connected by an ascending loop-like feature. While expanding,
the appearance of the feature remains remarkably constant as it passes
through the TRACE 195 Å passband and LASCO fields-of-view, allowing its
height-time behaviour to be acurately determined. The acceleration is
consistent with an exponential rise with an e-folding time of ∼138 s
and peaks at ∼1500 m s-2 when the leading-edge is at ∼1.7
R⊙ from Sun center. The acceleration subsequently falls
off with an e-folding time of over 1000 s. At distances beyond ∼3.4
R⊙ , the height-time profile is approximately linear with
a constant velocity of ∼2500 km s-1. These results are
briefly discussed in light of recent kinematic models of CMEs.

---------------------------------------------------------
Title: Hα , EUV, and Microwave Observations of a Large Flare as
Evidence for Spontaneous Magnetic Reconnection
Authors: Lee, J.; Gallagher, P. T.; Gary, D. E.; Nita, G. M.; Choe,
G. S.
2003SPD....34.1604L Altcode: 2003BAAS...35Q.833L
The large solar flare with GOES class X1.1 occurred on 2000 March 22
is observed with the Owens Valley Solar Array (OVSA), Hα filtergram
of Big Bear Solar observatory (bbso), the Transition region and Coronal
Explorer (trace), and the Michelson Doppler Imager (mdi) onboard Solar
and Heliospheric Observatory (SOHO). During the impulsive phase a set of
EUV loops are visible in a small volume confined to the center of the
large β γ δ -type active region. Radio emission at 5 GHz appears as
a single source encompassing multiple Hα ribbons, and radio emissions
at other frequencies also appear within the central core region. We
interpret these observations under the idea of the confined flare in
contrast with the more commonly cited, eruptive flare, using a schematic
magnetic reconnection geometry based on the mdi magnetogram. It is
suggested that the EUV loops represent a separatrix in part, and that
the radio and Hα sources coincide with the whole part of the separatrix
and its footpoints, respectively. In addition, a Coronal Mass Ejection
(CME) as detected in the LASCO coronagraph after this flare is briefly
discussed in relation to the above idea of magnetic reconnection. This work has been supported by NASA grants NAG 5-10891 and NAG-11875.

---------------------------------------------------------
Title: Observational Evidence for Mode Coupling in the Chromospheric
Network
Authors: McAteer, R. T. James; Gallagher, Peter T.; Williams, David R.;
Mathioudakis, Mihalis; Bloomfield, D. Shaun; Phillips, Kenneth J. H.;
Keenan, Francis P.
2003ApJ...587..806M Altcode:
Oscillations in network bright points (NBPs) are studied at a variety
of chromospheric heights. In particular, the three-dimensional
variation of NBP oscillations is studied using image segmentation
and cross-correlation analysis between images taken in light of Ca II
K3, Hα core, Mg I b2, and Mg I b1-0.4
Å. Wavelet analysis is used to isolate wave packets in time and
to search for height-dependent time delays that result from upward-
or downward-directed traveling waves. In each NBP studied, we find
evidence for kink-mode waves (1.3, 1.9 mHz), traveling up through the
chromosphere and coupling with sausage-mode waves (2.6, 3.8 mHz). This
provides a means for depositing energy in the upper chromosphere. We
also find evidence for other upward- and downward-propagating waves in
the 1.3-4.6 mHz range. Some oscillations do not correspond to traveling
waves, and we attribute these to waves generated in neighboring regions.

---------------------------------------------------------
Title: Hα, Extreme-Ultraviolet, and Microwave Observations of the
2000 March 22 Solar Flare and Spontaneous Magnetic Reconnection
Authors: Lee, Jeongwoo; Gallagher, Peter T.; Gary, Dale E.; Nita,
Gelu M.; Choe, G. S.; Bong, Su-Chan; Yun, Hong Sik
2003ApJ...585..524L Altcode:
The evolution of a GOES class X1.1 solar flare, which occurred
in NOAA Active Region 8910 on 2000 March 22, is discussed using
observations from the Owens Valley Solar Array (OVSA), Big Bear Solar
observatory (BBSO), Transition Region and Coronal Explorer (TRACE),
and the Michelson Doppler Imager (MDI) on board Solar and Heliospheric
Observatory (SOHO). During the impulsive phase, a set of coronal loops
are visible in the TRACE 171 Å (~1×106 K) wavelength
band, which is confined to a small volume in the center of the large
βγδ-type active region. This is rapidly followed by the emergence of
bright Hα ribbons that coincide with the EUV emission. Radio images
show a single source encompassing the Hα ribbons at 5 GHz, but at
higher frequencies a double source is seen within the area bounded by
the compact Hα and EUV emissions. We interpret the observation under
the idea of the confined flare in contrast with the more commonly cited,
eruptive flare. We use a schematic magnetic reconnection geometry based
on the MDI magnetogram to suggest that the EUV loops show some parts
of a separatrix, and that the radio and Hα sources coincide with the
whole part of the separatrix and its footpoints, respectively. First
of all, it explains why this flare lacks the separating motion of
Hα ribbons, a signature for eruptive flares. Second, the very short
duration of microwave bursts in spite of the large amount of soft
X-ray flux is explicable under this scenario, since energy release
via spontaneous reconnection in a confined magnetic structure can be
very rapid. Third, the confined magnetic geometry is also considered
favorable for preserving chromospheric evaporation and plasma turbulence
as inferred from the OVSA microwave spectrum. In addition, a coronal
mass ejection as detected in the LASCO coronagraph after this flare
is briefly discussed in relation to the above flare model.

---------------------------------------------------------
Title: Search for short period coronal plasma oscillations. SECIS
results from 1999 and 2001 total eclipses
Authors: Rudawy, P.; Phillips, K. J. H.; Read, P.; Gallagher, P. T.;
Rompolt, B.; Berlicki, A.; Williams, D.; Keenan, F. P.; Buczylko, A.
2002ESASP.506..967R Altcode: 2002ESPM...10..967R; 2002svco.conf..967R
Results of the analysis of the high-cadence observations of the solar
corona, taken with the Solar Eclipse Coronal Imaging System instrument
during joint British-Polish expeditions during the total solar eclipses
of 1999 August 11 in Bulgaria (12768 images) and 2001 June 21 in Zambia
(16000 images) are presented. Using data collected during the both solar
eclipses we searched for possible periodic changes of the 530.3 nm line
intensity emitted by the selected points of the solar corona in the
frequency range up to 10 Hz. The time resolution of the collected data
is close to 0.05 sec and the pixel size is approximately 4 seconds of
arc. The standard photometric processing and correction of the image
motions caused by temporal drifts of the instrument pointing were
made. Using classical Fourier spectral analysis and wavelet analysis
tools we investigated temporal changes of the 530.3 nm coronal line
brightness of many thousands of points at various heights and position
angles above the solar limb. We did not find any statistically important
evidence of periodicity in the frequency range from 1 to 10 Hz in any
of the investigated points.

---------------------------------------------------------
Title: RHESSI Observations of Flares During the Storms Period from
14 to 24 April 2002
Authors: Dennis, B. R.; Gallagher, P. T.
2002AGUFMSA12A..01D Altcode:
The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)
observes X-rays and gamma rays from solar flares in the energy range
from 3 keV to 17 MeV with a duty cycle of about 50%. The RHESSI
observations of the flares during the Storms Workshop period from 14
to 24 April, 2002, will be reviewed. Many GOES C- and M-class flares
were observed including the M2.6 flare on 17 April that was followed by
a CME. The X1.5 flare on 21 April was particularly well observed with
RHESSI in X-rays from its start at 00:40 UT until 01:33 UT on the first
orbit, just before the soft X-ray peak. Footpoint emission was detected
to energies as high as 200 keV, and a spatially-separated coronal
source was identified at energies below about 30 keV. The coronal X-ray
source was followed for over 12 more hours on subsequent orbits as it
gradually rose to over 130,000 km above the limb. The X-ray images and
spectra of this flare will be presented in relation to the TRACE images
in the 195-angstrom band and the LASCO images of the associated CME.

---------------------------------------------------------
Title: An observational study of a magneto-acoustic wave in the
solar corona
Authors: Williams, D. R.; Mathioudakis, M.; Gallagher, P. T.; Phillips,
K. J. H.; McAteer, R. T. J.; Keenan, F. P.; Rudawy, P.; Katsiyannis,
A. C.
2002MNRAS.336..747W Altcode:
The Solar Eclipse Corona Imaging System (SECIS) observed a strong 6-s
oscillation in an active region coronal loop, during the 1999 August 11
total solar eclipse. In the present paper we show that this oscillation
is associated with a fast-mode magneto-acoustic wave that travels
through the loop apex with a velocity of 2100 km s-1. We use
near-simultaneous SOHO observations to calculate the parameters of the
loop and its surroundings such as density, temperature and their spatial
variation. We find that the temporal evolution of the intensity is in
agreement with the model of an impulsively generated, fast-mode wave.

---------------------------------------------------------
Title: Rhessi and Trace Observations of the 21 April 2002 x1.5 Flare
Authors: Gallagher, Peter T.; Dennis, Brian R.; Krucker, Säm;
Schwartz, Richard A.; Tolbert, A. Kimberley
2002SoPh..210..341G Altcode:
Observations of the X1.5 flare on 21 April 2002 are reviewed using the
Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and the
Transition Region and Coronal Explorer (TRACE). The major findings are
as follows: (1) The 3-25 keV X-rays started &lt; 4 min before the EUV
(195 Å) emission suggesting that the initial energy release heated
plasma directly to ≳20 MK, well above the 1.6 MK needed to produce the
Fe xii (195 Å) line. (2) Using coaligned 12-25 keV RHESSI and TRACE
images, further evidence is found for the existence of hot (15-20 MK)
plasma in the 195 Å passband. This hot, diffuse emission is attributed
to the presence of the Fe xxiv (192 Å) line within the TRACE 195 Å
passband. (3) The 12-25 keV source centroid moves away from the limb
with an apparent velocity of ∼ 9.9 km s−1, slowing to ∼
1.7 km s−1 after 3 hours, its final altitude being ∼ 140
Mm after ∼ 12 hours. This suggests that the energy release site moves
to higher altitudes in agreement with classical flare models. (4) The
50-100 keV emission correlates well with EUV flare ribbons, suggesting
thick-target interactions at the footpoints of the magnetic arcade. The
50-100 keV time profile matches the time derivative of the GOES light
curve (Neupert effect), which suggests that the same electrons that
produced the thick-target hard X-ray emission also heat the plasma seen
in soft X-rays. (5) X-ray footpoint emission has an E−3
spectrum down to ∼ 10 keV suggesting a lower electron cutoff energy
than previously thought. (6) The hard X-ray (25-200 keV) peaks have
FWHM durations of ∼ 1 min suggesting a more gradual energy release
process than expected. (7) The TRACE images reveal a bright symmetric
front propagating away from the main flare site at speeds of ≥ 120
km s−1. This may be associated with the fast CME observed
several minutes later by LASCO. (8) Dark sinuous lanes are observed in
the TRACE images that extend almost radially from the post-flare loop
system. This `fan of spines' becomes visible well into the decay phase
of the flare and shows evidence for both lateral and downward motions.

---------------------------------------------------------
Title: Detections of high-frequency oscillations in solar active
region coronal loops
Authors: Katsiyannis, Athanassios C.; Williams, David R.; McAteer,
R. T. James; Gallagher, Peter T.; Mathioudakis, Mihalis; Keenan,
Francis P.
2002ESASP.505..441K Altcode: 2002IAUCo.188..441K; 2002solm.conf..441K
One of the mechanisms proposed as a possible solution to the
Sun's coronal heating problem is the damping of energy carried by
magnetohydrodynamic (MHD) waves that are expected to be present
in active regions. Continuing previous work on total solar eclipse
data, we provide further obervational evidence for the existence of
high-frequency MHD waves in coronal loops. Wavelet analysis is used to
identify 21 areas of 4×4 arcsec2 with periodic intensity
oscillations. The frequency range of these detections was 0.2-0.3 Hz
and all last for at least 3 periods at a confidence level of more than
99%. All of the above detections are made just outside known coronal
loops, leading us to suggest a possible, unconventional mechanism.

---------------------------------------------------------
Title: Detection of propagating waves throughout the chromosphere
in network bright points
Authors: McAteer, R. T. James; Gallagher, Peter T.; Williams, David
R.; Mathioudakis, Mihalis; Phillips, Kenneth J. H.; Keenan, Francis P.
2002ESASP.505..305M Altcode: 2002IAUCo.188..305M; 2002solm.conf..305M
We analysed oscillations in individual Network Bright Points (NBPs)
in Ca II K3, Hα core, Mg I b2, and Mg I
b1-0.4 Å giving us a range of heights from the upper
to the lower chromosphere. Lightcurves, and hence power spectra,
were created by isolating distinct regions of the NBP via a simple
intensity thresholding technique. Using this technique, it was
possible to identify peaks in the power spectra with particular spatial
positions within the NBPs. This was extended into the time domain by
means of wavelet analysis. We track the temporal evolution of power
in particular frequency bands by creating power curves. These are
then cross-correlated across all observed wavelengths to search for
propagating waves. In particular, long-period waves with periods of
4-15 minutes (1-4 mHz) were found in the central portion of each NBP,
indicating that these waves are certainly not acoustic, but possibly
due to magneto-acoustic or magneto-gravity wave modes. We note the
possible existence of fast-mode MHD waves in the lower chromosphere,
coupling and transferring power top higher-frequency slow-mode MHD
waves in the upper chromosphere.

---------------------------------------------------------
Title: Observations of a high-frequency, fast-mode wave in a
coronal loop
Authors: Williams, David R.; Mathioudakis, Mihalis; Gallagher, Peter
T.; Phillips, Kenneth J. H.; McAteer, R. T. James; Keenan, Francis P.;
Katsiyannis, Athanassios C.
2002ESASP.505..615W Altcode: 2002IAUCo.188..615W; 2002solm.conf..615W
The high-cadence Solar Eclipse Corona Imaging System (SECIS) observed
a strong 6-second oscillation in an active region coronal loop, during
the 1999 August 11 total solar eclipse. In the present paper we show
that this oscillation is associated with a fast-mode wave that travels
through the loop apex with a velocity of ~2000 km s-1. We
use near-simultaneous SoHO/CDS obervations to calculate the parameters
of the loop and its surroundings such as density, temperature and their
spatial variation. We also calculate radiative losses from the loop in
the temperature range 105.8 - 106.4K, and compare
these losses with the wave energy density. Although the wave travels a
distance greater than λ/4π and therefore meets a necessary criterion
for slow dissipation, the dissipation length is well in excess of the
loop length. The temporal evolution of the intensity is found to be
in agreement with the model of an impulsively generated, fast-mode wave.

---------------------------------------------------------
Title: Active-Region Monitoring and Flare Forecasting I. Data
Processing and First Results
Authors: Gallagher, Peter T.; Moon, Y. -J.; Wang, Haimin
2002SoPh..209..171G Altcode:
This paper discusses a near real-time approach to solar active-region
monitoring and flare prediction using the Big Bear Solar Observatory
Active Region Monitor (ARM). Every hour, ARM reads, calibrates,
and analyses a variety of data including: full-disk Hα images from
the Global Hα Network; EUV, continuum, and magnetogram data from the
Solar and Heliospheric Observatory (SOHO); and full-disk magnetograms
from the Global Oscillation Network Group (GONG). For the first time,
magnetic gradient maps derived from GONG longitudinal magnetograms are
now available on-line and are found to be a useful diagnostic of flare
activity. ARM also includes a variety of active-region properties
from the National Oceanic and Atmospheric Administration's Space
Environment Center, such as up-to-date active-region positions, GOES
5-min X-ray data, and flare-to-region identifications. Furthermore,
we have developed a Flare Prediction System which estimates the
probability for each region to produce C-, M-, or X-class flares based
on nearly eight years of NOAA data from cycle 22. This, in addition
to BBSO's daily solar activity reports, has proven a useful resource
for activity forecasting.

---------------------------------------------------------
Title: Solar Submillimeter and Gamma-Ray Burst Emission
Authors: Kaufmann, P.; Raulin, J. -P.; Melo, A. M.; Correia, E.; Costa,
J. E. R.; de Castro, C. G. Giménez; Silva, A. V. R.; Yoshimori, M.;
Hudson, H. S.; Gan, W. Q.; Gary, D. E.; Gallagher, P. T.; Levato,
H.; Marun, A.; Rovira, M.
2002ApJ...574.1059K Altcode:
Solar flare emission was measured at 212 GHz in the submillimeter
range by the Submillimeter Solar Telescope in the 1.2-18 GHz microwave
range by the Owens Valley Solar Array and in the gamma-ray energy
range (continuum) by experiments on board the Yohkoh (&gt;1.2 MeV)
and Shenzhou 2 (&gt;0.2 MeV) satellites. At the burst onset, the
submillimeter and microwave time profiles were well correlated with
gamma rays to the limit of the temporal resolution (&lt;=10 s). At 212
GHz, fast pulses (&lt;1 s), defined as time structures in excess of the
bulk emission, were identified as the flux increased. Their spatial
positions were scattered by tens of arcseconds with respect to the
main burst emission position. Correlation of submillimeter emission
with gamma-ray fast time structures shorter than 500 ms is suggested
at the gamma-ray maximum. The time variation of the rate of occurrence
of the submillimeter rapid pulses was remarkably well correlated with
gamma-ray intensities in the energy range (&gt;1.2 MeV), attaining
nearly 50 pulses per minute at the maximum. These results suggest that
gamma rays might be the response to multiple rapid pulses at 212 GHz
and might be produced at different sites within the flaring region.

---------------------------------------------------------
Title: Statistical Evidence for Sympathetic Flares
Authors: Moon, Y. -J.; Choe, G. S.; Park, Y. D.; Wang, Haimin;
Gallagher, Peter T.; Chae, Jongchul; Yun, H. S.; Goode, Philip R.
2002ApJ...574..434M Altcode:
Sympathetic flares are a pair of flares that occur almost simultaneously
in different active regions, not by chance, but because of some
physical connection. In this paper statistical evidence for the
existence of sympathetic flares is presented. From GOES X-ray flare
data, we have collected 48 pairs of near simultaneous flares whose
positional information and Yohkoh soft X-ray telescope images
are available. To select the active regions that probably have
sympathetic flares, we have estimated the ratio R of actual flaring
overlap time to random-coincidence overlap time for 38 active region
pairs. We have then compared the waiting-time distributions for the
two different groups of active region pairs (R&gt;1 and R&lt;1) with
corresponding nonstationary Poisson distributions. As a result, we
find a remarkable overabundance of short waiting times for the group
with R&gt;1. This is the first time such strong statistical evidence
has been found for the existence of sympathetic flares. To examine
the role of interconnecting coronal loops, we have also conducted
the same analysis for two subgroups of the R&gt;1 group: one with
interconnecting X-ray loops and the other without. We do not find any
statistical evidence that the subgroup with interconnecting coronal
loops is more likely to produce sympathetic flares than the subgroup
without. For the subgroup with loops, we find that sympathetic flares
favor active region pairs with transequatorial loops.

---------------------------------------------------------
Title: Solar activity monitoring and forecasting capabilities at
Big Bear Solar Observatory
Authors: Gallagher, P. T.; Denker, C.; Yurchyshyn, V.; Spirock, T.;
Qiu, J.; Wang, H.; Goode, P. R.
2002AnGeo..20.1105G Altcode:
The availability of full-disk, high-resolution Ha

---------------------------------------------------------
Title: Electron Transport during the 1999 August 20 Flare Inferred
from Microwave and Hard X-Ray Observations
Authors: Lee, Jeongwoo; Gary, Dale E.; Qiu, Jiong; Gallagher, Peter T.
2002ApJ...572..609L Altcode:
We discuss injection and transport of high-energy electrons during
a GOES X-ray class M9.8 flare observed in microwaves with the Owens
Valley Solar Array (OVSA) and in hard X-rays (HXRs) with the hard
X-ray telescope (HXT) on board Yohkoh. Observed at 1 s timescales
or better in both wavelength regimes, the event shows (1) a large
difference in scale between the microwave source and the HXR source;
(2) an unusually hard HXR spectrum (maximum spectral index ~-1.6),
followed by rapid spectral softening; and (3) a microwave light curve
containing both impulsive peaks (3 s rise time) simultaneous with
those of the HXRs and a long, extended tail with a uniform decay rate
(2.3 minutes). We analyze the observations within the framework of
the electron trap-and-precipitation model, allowing a time-dependent
injection energy spectrum. Assuming thick-target bremsstrahlung
for the HXRs, we infer the electron injection function in the form
Q(E,t)~(E/E0)-δ(t), where the timescale for
δ(t) to change by unity is ~7 s. This injection function can account
for the characteristics of the impulsive part of the microwave burst
by considering the bulk of the electrons to be directly precipitating
without trapping. The same injection function also accounts for the
gradual part of the microwave emission by convolving the injection
function with a kernel representing the trapping process, which at late
times gives N(E,t)~e-νt(E/E0)-b. We
require b~1.4 and ν~6×10-3β s-1, where β
is the electron speed divided by the speed of light. Therefore, the
derived form of the precipitation rate ν itself indicates strong
pitch-angle diffusion, but the slow decay of the microwave radiation
requires a small loss cone (~4°) and a low ambient density in the
coronal trap. Also, the numbers of electrons needed to account for
the two components of the microwave emission differ by an order of
magnitude. We estimate that the &gt;=100 keV number of the directly
precipitating electrons is ~1033, while the trapped
population requires ~1032 electrons. This leads us to
a model of two interacting loops, the larger of which serves as an
efficient trap while the smaller provides the impulsive source. These
characteristics are consistent with the spatially resolved observations.

---------------------------------------------------------
Title: Solar Flare Spectroscopy and Imaging with CDS and TRACE
Authors: Gallagher, P. T.
2002AAS...200.6807G Altcode: 2002BAAS...34..756G
In this poster we discuss recent CDS and TRACE observations of a number
of small and intermediate magnitude solar flares. In particular,
we focus on a C3.0 flare which occurred on 26 March 2002 peaking at
15:21 UT. The event is first observed as two simultaneous foot-point
brightenings in He I (584.33 A), followed by distinct loop-top emission
visible in Fe XIX (592.16 A), which has a formation temperature of
close to 10,000,000 K. As this high-temperature emission begins to
cool, a cusp-shaped feature then becomes visible in Mg X (624.94 A)
and Fe XVI (360.76 A). In addition to the morphology of the event
seen in CDS and TRACE (171 A) images, a detailed analysis of CDS line
parameters such as line position, width, and intensity is discussed
in light of current solar flare models.

---------------------------------------------------------
Title: Core and Large-Scale Structure of the 2000 November 24 X-Class
Flare and Coronal Mass Ejection
Authors: Wang, Haimin; Gallagher, Peter; Yurchyshyn, Vasyl; Yang,
Guo; Goode, Philip R.
2002ApJ...569.1026W Altcode:
In this paper, we present three important aspects of the X1.8 flare
and the associated coronal mass ejection (CME) that occurred on 2000
November 24: (1) The source of the flare is clearly associated with
a magnetic channel structure, as was noted in a study by Zirin &amp;
Wang , which is due to a combination of flux emergence inside the
leading edge of the penumbra of the major leading sunspot and proper
motion of the sunspot group. The channel structure provides evidence for
twisted flux ropes that can erupt, forming the core of a CME, and may
be a common property of several superactive regions that have produced
multiple X-class flares in the past. (2) There are actually three flare
ribbons visible. The first can be seen moving away from the flare site,
while the second and third make up a stationary ribbon near the leader
spot. The moving ribbons could be due to a shock associated with the
erupting flux rope or due to the interaction of erupting rope and the
surrounding magnetic fields. In either case, the ribbon motion does
not fit the classical Kopp-Pneuman model, in which the separation
of ribbons is due to magnetic reconnection at successively higher
and higher coronal altitudes. (3) From the coronal dimming observed
with the EUV Imaging Telescope (EIT), the CME involved a much larger
region than the initial X-class flare. By comparing high-resolution
full-disk Hα and EIT observations, we found that a remote dimming
area is cospatial with the enhanced Hα emission. This result is
consistent with the recent model of Yokoyama &amp; Shibata that some
dimming areas near footpoints may be due to chromospheric evaporation.

---------------------------------------------------------
Title: Long-Period Chromospheric Oscillations in Network Bright Points
Authors: McAteer, R. T. James; Gallagher, Peter T.; Williams, David
R.; Mathioudakis, Mihalis; Phillips, Kenneth J. H.; Keenan, Francis P.
2002ApJ...567L.165M Altcode:
The spatial variation of chromospheric oscillations in network bright
points (NBPs) is studied using high-resolution observations in Ca II
K3. Light curves and hence power spectra were created by isolating
distinct regions of the NBP via a simple intensity thresholding
technique. Using this technique, it was possible to identify peaks in
the power spectra with particular spatial positions within the NBPs. In
particular, long-period waves with periods of 4-15 minutes (1-4 mHz)
were found in the central portions of each NBP, indicating that these
waves are certainly not acoustic but possibly due to magnetoacoustic
or magnetogravity wave modes. We also show that spatially averaged
or low spatial resolution power spectra can lead to an inability to
detect such long-period waves.

---------------------------------------------------------
Title: RHESSI and TRACE Observations of an X-class Flare
Authors: Hudson, H.; Dennis, B.; Gallagher, P.; Krucker, S.; Reeves,
K.; Warren, H.
2002cosp...34E3101H Altcode: 2002cosp.meetE3101H
RHESSI and TRACE both obtained excellent observations of an X1.5 flare
on April 21, 2002. In this paper we provide an overview of the flare
and discuss the high- energy imaging and spectra in detail. The TRACE
images in the 195A passband (Fe XII and FeXXIV) reveal this flare to
have a spiky arcade with post-flare flow field in the "supra-arcade
downflow" pattern discovered by Yohkoh. Below the spikes, but above
the FeXII loops, TRACE observes a region with complex motions and fine
structure. We confirm with RHESSI that this region has an elevated
temperature and discuss the transition between thermal and non-thermal
sources. RHESSI also observes footpoint emission distributed along
the flare ribbons.

---------------------------------------------------------
Title: Space Weather: The Scientific Forecast
Authors: Wang, H.; Gallagher, P. T.; Yurchyshyn, V.
2002stma.conf..375W Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Impulsive Events and Coronal Loop Cooling Observed with TRACE
Authors: Seaton, D. B.; DeLuca, E. E.; Golub, L.; Reeves, K. K.;
Winebarger, A. R.; Gallagher, P. T.
2001AGUFMSH11A0705S Altcode:
Nearly every active region imaged by TRACE contains sporadic
brightenings in coronal loops. Many of these ubiquitous, short-lived
events appear nearly simultaneously in the Fe IX/X (log T
e≈ 6.0) and the C IV channel (log T≈ 5.0); hence, we interpret
them as the rapid cooling of a multifilament loops. A particularly good
example of such an event was observed on 21, June 2001, as part of an
hour long active region observation; a total of 52 of the TRACE 171
Å and 68 TRACE 1600 Å images have been analyzed from that sequence,
as well as 35 images provided by the MDI aboard SOHO. In this poster,
we will discuss the analysis of the events and the implications of
our cooling model.

---------------------------------------------------------
Title: Active Region Transient Events Observed with TRACE
Authors: Seaton, Daniel B.; Winebarger, Amy R.; DeLuca, Edward E.;
Golub, Leon; Reeves, Katharine K.; Gallagher, Peter T.
2001ApJ...563L.173S Altcode:
Nearly all active region observations made by the Transition Region
and Coronal Explorer (TRACE) contain seemingly spontaneous, short-lived
brightenings in small-scale loops. In this paper, we present an analysis
of these brightenings using high-cadence TRACE observations of Active
Region 9506 on 2001 June 21 from 15:17:00 to 15:46:00 UT. During this
time frame, several brightenings were observed over a neutral line in
a region of emerging flux that had intensity signatures in both the
171 Å (logTe~6.0) and 1600 Å (logTe~4.0-5.0)
channels. The events had a cross-sectional diameter of approximately
2" and a length of 25". We interpret these as reconnection events
associated with flux emergence, possible EUV counterparts to active
region transient brightenings.

---------------------------------------------------------
Title: Electron Densities in the Coronae of the Sun and Procyon from
Extreme-Ultraviolet Emission Line Ratios in Fe XI
Authors: Pinfield, D. J.; Keenan, F. P.; Mathioudakis, M.; Widing,
K. G.; Gallagher, P. T.; Gupta, G. P.; Tayal, S. S.; Thomas, R. J.;
Brosius, J. W.
2001ApJ...562..566P Altcode:
New R-matrix calculations of electron impact excitation rates for Fe
XI are used to determine theoretical emission line ratios applicable
to solar and stellar coronal observations. These are subsequently
compared to solar spectra of the quiet Sun and an active region made
by the Solar EUV Rocket Telescope and Spectrograph (SERTS-95), as well
as Skylab observations of two flares. Line blending is identified,
and electron densities of 109.3, 109.7,
&gt;=1010.8, and &gt;=1011.3 cm-3
are found for the quiet Sun, active region, and the two flares,
respectively. Observations of the F5 IV-V star Procyon, made with
the Extreme Ultraviolet Explorer (EUVE) satellite, are compared and
contrasted with the solar observations. It is confirmed that Procyon's
average coronal conditions are very similar to those seen in the quiet
Sun, with Ne=109.4 cm-3. In addition,
although the quiet Sun is the closest solar analog to Procyon, we
conclude that Procyon's coronal temperatures are slightly hotter than
solar. A filling factor of 25+38-12% was derived
for the corona of Procyon.

---------------------------------------------------------
Title: High-frequency oscillations in a solar active region coronal
loop
Authors: Williams, D. R.; Phillips, K. J. H.; Rudawy, P.; Mathioudakis,
M.; Gallagher, P. T.; O'Shea, E.; Keenan, F. P.; Read, P.; Rompolt, B.
2001MNRAS.326..428W Altcode:
The Solar Eclipse Corona Imaging System (SECIS) was used to record
high-cadence observations of the solar corona during the total solar
eclipse of 1999 August 11. During the 2min 23.5s of totality, 6364
images were recorded simultaneously in each of the two channels:
a white light channel, and the Fexiv (5303Å) `green line' channel
(T~2MK). Here we report initial results from the SECIS experiment,
including the discovery of a 6-s intensity oscillation in an active
region coronal loop.

---------------------------------------------------------
Title: The Extreme-Ultraviolet Structure and Properties of a Newly
Emerged Active Region
Authors: Gallagher, Peter T.; Phillips, Kenneth J. H.; Lee, Jeongwoo;
Keenan, Francis P.; Pinfield, David J.
2001ApJ...558..411G Altcode:
The structure and properties of a newly emerged solar active
region (NOAA Active Region 7985) are discussed using the Coronal
Diagnostic Spectrometer (CDS) and the Extreme-Ultraviolet Imaging
Telescope (EIT) on board the Solar and Heliospheric Observatory. CDS
obtained high-resolution EUV spectra in the 308-381 Å and 513-633
Å wavelength ranges, while EIT recorded full-disk EUV images in
the He II (304 Å), Fe IX/X (171 Å), Fe XII (195 Å), and Fe XV
(284 Å) bandpasses. Electron density measurements from Si IX,
Si X, Fe XII, Fe XIII, and Fe XIV line ratios indicate that the
region consists of a central high-density core with peak densities
of the order of 1.2×1010 cm-3, which
decrease monotonically to ~5.0×108 cm-3
at the active region boundary. The derived electron densities
also vary systematically with temperature. Electron pressures as
a function of both active region position and temperature were
estimated using the derived electron densities and ion formation
temperatures, and the constant pressure assumption was found to be
an unrealistic simplification. Indeed, the active region is found
to have a high-pressure core (1.3×1016 cm-3
K) that falls to 6.0×1014 cm-3 K just outside
the region. CDS line ratios from different ionization stages of iron,
specifically Fe XVI (335.4 Å) and Fe XIV (334.4 Å), were used to
diagnose plasma temperatures within the active region. Using this
method, peak temperatures of 2.1×106 K were identified. This
is in good agreement with electron temperatures derived using EIT
filter ratios and the two-temperature model of Zhang et al. The
high-temperature emission is confined to the active region core,
while emission from cooler (1-1.6)×106 K lines originates
in a system of loops visible in EIT 171 and 195 Å images. Finally,
the three-dimensional geometry of the active region is investigated
using potential field extrapolations from a Kitt Peak magnetogram. The
combination of EUV and magnetic field extrapolations extends the
“core-halo” picture of active region structure to one in which the
core is composed of a number of compact coronal loops that confine the
hot, dense, high-pressure core plasma while the halo emission emerges
from a system of cooler and more extended loops.

---------------------------------------------------------
Title: Asymmetric Behavior of Hα Footpoint Emission during the
Early Phase of an Impulsive Flare
Authors: Qiu, Jiong; Ding, Ming D.; Wang, Haimin; Gallagher, Peter T.;
Sato, Jun; Denker, Carsten; Goode, Philip R.
2001ApJ...554..445Q Altcode:
We study the impulsive phase of a C9.0 solar flare using high temporal
and spatial resolution Hα images from Big Bear Solar Observatory (BBSO)
in conjunction with high-cadence hard X-ray (HXR) observations from
Yohkoh. During the early impulsive phase, HXR emission emerged from
two kernels K1 and K2 which were connected by coronal loops observed
in soft X-ray (SXR) images from Yohkoh. In Hα, the initial rise was
observed in one flare kernel K2, which was followed within 10 s by
enhanced emission in the associated kernel K1. Such a significant
asymmetry was not observed at HXR wavelengths. Our analysis shows
that the asymmetric Hα footpoint emission cannot be explained by the
magnetic mirroring effect in which strong field footpoints show lower
precipitation rates. Instead, we study this phenomenon by investigating
the atmospheric response of the lower chromosphere to nonthermal
beam heating. From numerical simulations, it is suggested that a cool
atmosphere does not respond rapidly to beam impact, which may explain
the missing Hα emission at K1 during the early impulsive phase. At K2,
the early-phase atmosphere may be preferentially heated resulting in
the Hα emission rapidly following the HXR emission. This is due to
the fact that K2 is a compact source which received persistent energy
deposition and consequent heating in a confined area during the early
phase. K1, on the other hand, is a diffused source which therefore
experienced a lower heating rate per unity area. We propose a scenario
in which the flare loop consists of multiple magnetic “threads”
connecting the compact footpoint K2 with the diffuse footpoint K1.

---------------------------------------------------------
Title: Optical, EUV, and Microwave Observations of the March 22,
2000 X-class Flare.
Authors: Gallagher, P. T.; Gary, D. E.; Lee, J.
2001AGUSM..SP42A08G Altcode:
The evolution of an X-class flare which occured in NOAA 8910 on March
22, 2000 is discussed using observations from the Owens Valley Solar
Array (ovsa), Big Bear Solar Observatory (bbso), the Transition
Region and Coronal Explorer (trace), and the Michelson Doppler
Imager (mdi). The main energy release occurs in a set of coronal
loops visible in the trace 171 Å (1 x 106~K) wavelength
band, which is rapidly followed by the emergence of two bright Hα
ribbons. High-cadence radio images at around 5 GHz obtained using the
ovsa appears in the middle of two Hα ribbons, which thus indicates
presence of energetic electrons flowing across the two ribbons. During
the impulsive phase, short-lived (τ &lt;= 30 s), narrow-band (BW
&lt;= 500 MHz), and highly polarized microwave emission is observed in
radio images in the 1-2 GHz frequency range, which is possibly due to
plasma radiation. At optically-thin, high frequencies ovsa total power
spectra also show a typical soft-hard-soft evolution indicative of
highly efficient nonthermal electron acceleration during the impulsive
phase. The microwave emission from this flare is surprisingly short
considering that active region is large (&gt; 200 arc sec in diameter)
and the flare is energetic (GOES X class). We consider that the compact
magnetic field geometry in the flaring region and subsequent strong
chromospheric evaporation into it may have limited life of high energy
electrons trapped in the loops to such a short duration.

---------------------------------------------------------
Title: Radio and X ray Observations of a Limb Flare during the Max
Millennium Campaign
Authors: Lee, J.; Gallagher, P. T.; Gary, D. E.; Harra, L. K.
2001AGUSM..SP51A03L Altcode:
A powerful (GOES Class M9.8), limb flare was observed on 1999 August
20 above AR 8673 during the second Max Millennium campaign. Due to its
location on the limb as well as its strength, the flare observation
provides an ideal case of studying vertical structure of electron
acceleration and its transport. The hard X ray images from Yohkoh/HXT
along with EUV images from SoHO/EIT show an impulsive, compact double
brightening in the lower atmosphere and a hypothesis of footpoint
emission from a compact loop seems likely. In contrast, microwave
visibilities obtained using the Owens Valley Solar Array (OVSA) suggest
a region of high energy electrons high in the corona (2x 105
km), requiring large loops that can act as a good trap of electrons. The
duration of radio emission is also much extended compared with the
hard X ray emission. We present this set of observations as a good
example of the trap-plus-precipitation hypothesis, and derive numbers
of electrons emitting the microwaves and hard X rays, respectively, as
a measure for the trap vs. precipitation. The derived time evolution
of electron numbers in energy space is not compatible with a simple
hypothesis of energy-independent acceleration solely under Coulomb
collisions, but instead requires an acceleration or transport process
that is highly energy-dependent.

---------------------------------------------------------
Title: Results from the Big Bear Solar Observatory's New Digital
Vector Magnetograph
Authors: Spirock, T. J.; Denker, C.; Varsik, J.; Shumko, S.; Qiu,
J.; Gallagher, P.; Chae, J.; Goode, P.; Wang, H.
2001AGUSM..SP51B06S Altcode:
During the past several years the Big Bear Solar Observatory has
been involved in an aggressive program to modernize the observatory's
instrumentation. At the forefront of this effort has been the upgrade
of the observatory's digital vector magnetograph (DVMG), which has been
recently integrated into the observatory's daily observing program. The
DVMG, which is mounted on the observatory's 25 cm vacuum refractor,
is a highly sensitive, high cadence magnetograph which studies the
FeI line at 630.1 nm. An easy to use GUI observing tool has been
written to aid instrument development and data acquisition. This
tool automatically calibrates the data and generates near real-time
vector magnetograms which will aid space weather forecasting and the
support of space weather missions. Also, our plan is to integrate the
DVMG data into the HESSI Synoptic Archive. The very sensitive quiet
Sun magnetograms, produced by the DVMG, will aid the study of small
scale magnetic reconnection at the intranetwork level and its possible
contribution to the coronal heating problem. Quiet sun longitudinal and
active region vector magnetograms will be presented. Image quality,
such as bias, cross-talk, noise levels and sensitivity, will be
discussed in addition to the improvements gained in post processing
such as image selection and image alignment.

---------------------------------------------------------
Title: Cornoal Heating by MHD Waves: Results from the SECIS Instrument
during the 1999 Eclipse
Authors: Phillip, K. J. H.; Gallagher, P. T.; Williams, D. R.; Keenan,
F. P.; Rudawy, P.; Rompolt, B.; Berlicki, A.
2001IAUS..203..467P Altcode:
We report on observational evidence for the rôles that small flare-like
events and short-period MHD waves play in the heating of the solar
corona. In several studies of SOHO and Yohkoh data, we examine the
numbers and energies of small events in the EUV and in soft X-rays
can account for the necessary energetics of the quiet-Sun corona,
finding that EUV events at least might be sufficient to provide the
heating, at least in closed-field regions. Results will be summarized
in this paper. However, MHD waves may still play an important part,
and in a separate investigation we have used fast-cadence imaging of
the white-light and green-line corona during the total eclipse of 1999
August 11 to search for short-period modulations. The imaging system
is the Solar Eclipse Coronal Imaging System (SECIS), and consists of a
pair of CCD cameras and an adapted PC to form images of the corona at
a frame rate of 44 s-1. Preliminary analysis of the data
suggests the presence of fast changes over the 2-minute-long period
of eclipse totality. This paper will also report on the SECIS data.

---------------------------------------------------------
Title: Characteristics of quiet Sun cell and network brightenings
Authors: Harra, L. K.; Gallagher, P. T.; Phillips, K. J. H.
2000A&A...362..371H Altcode:
Extreme ultraviolet observations of the quiet Sun are made with
the Coronal Diagnostic Spectrometer (cds) on board the Solar and
Heliospheric Observatory (soho). It has been previously noted that
frequent transition region brightenings occur in both the bright
network and dark cell regions. Analysing 1125 events, we determined
the characteristics of the brightenings in the cell and network
regions which include the duration, energy, and intensity increase
above the background. Network brightenings are found to be larger than
cell events occurring with a mean duration of 150 s and releasing an
average of 1026.9 ergs per event. Cell brightenings, on the
other hand, last for an average of 96 s and release 1025.8
ergs per event. It has also been found that the distribution of
energy is a power-law which is different in the cell (gamma =2.5)
and network (gamma =1.5) regions. When the entire quiet Sun region
is analysed the value of gamma is 1.7. The number of events per cds
pixel is approximately the same, and a histogram of the ratio ([peak
value - background]/background) shows similar values for both the
cell and network. It is important to analyse the cell and network
regions separately in the context of coronal heating by such small
flare-like events.

---------------------------------------------------------
Title: The Radial and Angular Variation of Electron Density in the
Solar Corona.
Authors: Gallagher, P. T.; Mathioudakis, M.; Phillips, K. J. H.;
Tsinganos, K.; Keenan, F. P.
2000SPD....31.0234G Altcode: 2000BAAS...32.1290G
We derive, for the first time, electron densities as a function of
both radius (R) and position angle (θ ) for the south-west quadrant of
the off-limb corona, using the density-sensitive Si ix (349.9 Å/341.9
Å) and Si x (356.0 Å/347.7 Å) extreme ultraviolet line ratios. The
observations were made with the Coronal Diagnostic Spectrometer (cds)
on board the Solar and Heliospheric Observatory (soho), over the range
1.00R⊙ &lt; R &lt; 1.20R⊙ and 180° &lt;
θ &lt; 270° . Within the south polar coronal hole, the density varies
from 2.3 x 108 cm-3 at 1.0R⊙ to 8.3x
107 cm-3 at 1.20R⊙ , while at the
equator the density varies from 6.3 x 108 cm-3
at 1.0R⊙ to 1.6x 108 cm-3 at
1.20R⊙ . The density falloff with height is therefore
faster in the equatorial region. We also find that electron densities
are, on average, a factor of 2.7 larger in the equatorial regions than
in the polar coronal hole at a given radial distance. Finally, we find
remarkable agreement between our measured densities as a function of
radius and position angle and those predicted by a recent analytic
MHD model of the solar wind, strongly supporting its basic premises.

---------------------------------------------------------
Title: Multi-wavelength observations of the 1998 September 27
flare spray
Authors: Gallagher, Peter T.; Williams, David R.; Phillips, Kenneth
J. H.; Mathioudakis, Mihalis; Smartt, Raymond N.; Keenan, Francis P.
2000SoPh..195..367G Altcode:
We report on observations of a large eruptive event associated with a
flare that occurred on 27 September 1998 made with the Richard B. Dunn
Solar Telescope at Sacramento Peak Observatory (several wave bands
including off-line-center Hα), in soft and hard X-rays (GOES and
BATSE), and in several TRACE wave bands (including Fe ix/x 171 Å,
Fe xii 195 Å, and C iv 1550 Å). The flare initiation is signaled by
two Hα foot-point brightenings which are closely followed by a hard
X-ray burst and a subsequent gradual increase in other wavelengths. The
flare light curves show a complicated, three-component structure which
includes two minor maxima before the main GOES class C5.2 peak after
which there is a characteristic exponential decline. During the initial
stages, a large spray event is observed within seconds of the hard
X-ray burst which can be directly associated with a two-ribbon flare
in Hα. The emission returns to pre-flare levels after about 35 min,
by which time a set of bright post-flare loops have begun to form at
temperatures of about 1.0-1.5 MK. Part of the flare plasma also intrudes
into the penumbra of a large sunspot, generally a characteristic of
very powerful flares, but the flare importance in GOES soft X-rays is in
fact relatively modest. Much of the energy appears to be in the form of
a second ejection which is observed in optical and ultraviolet bands,
traveling out via several magnetic flux tubes from the main flare site
(about 60° from Sun center) to beyond the limb.

---------------------------------------------------------
Title: Transition region and coronal structuring
Authors: O'Shea, E.; Gallagher, P. T.; Mathioudakis, M.; Phillips,
K. J. H.; Keenan, F. P.; Katsiyannis, A. C.
2000A&A...358..741O Altcode:
In this paper we examine regions of internetwork, network and bright
network emission, observed in the quiet Sun with the Coronal Diagnostic
Spectrometer (cds) onboard SoHO. The slopes of the emission measure
distributions, between 5.4 &lt;= log Te &lt;= 6.0, are
found to differ in each region, suggesting the presence of different
atmospheric structures. From an analysis of emission area the network
is shown to have two populations of structures, a low transition region
group and a coronal group. Using mdi magnetograms the bright network
emission is shown to originate from regions of strong magnetic field
composed of bipolar loops and unipolar funnels, that extend from the
low transition region up to the corona. Up to 30% of all radiative
losses between 5.7 &lt;= log Te &lt;= 6.3 are found to come
from these continuous bright network structures. Cross-sectional areas
calculated from redshift values suggest that the area expansion seen
in the bright network emission is the result of flux tube expansion
into the corona, accompanied by either a downflow or upflow of material.

---------------------------------------------------------
Title: First results from the upgraded Owens Valley Solar Array.
Authors: Gary, D. E.; Hurford, G. J.; Lee, J.; Gallagher, P. T.
2000BAAS...32..818G Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Magnetic Reconnection and Energetics of the 2000 March 22
Solar Flare
Authors: Gallagher, P. T.; Gary, D. E.; Lee, J.
2000SPD....31.0260G Altcode: 2000BAAS...32..821G
The evolution and properties of the 2000 March 22 X--class flare from
the β δ active region NOAA 8910 are discussed using high resolution
radio observations from the Owen's Valley Solar Array, TRACE UV and
EUV filtergrams, GOES soft X-rays, and magnetograms from MDI on board
SOHO. The episodic flare evolution is found to be extremely complicated
at all observed wavelengths and releases a large amount of both thermal
and non--thermal energy. From the UV and EUV observations, the flare is
shown to be consistent with the model in which the release of energy
is caused by several, successive loop interactions while the radio
observations identify multiple non--thermal electron acceleration
sites. The final stage of the flare is then characterised by the
emergence of a set of post--flare loops parallel to the magnetic
neutral line as the system relaxes.

---------------------------------------------------------
Title: Electron Acceleration During the 1999 August 20 Flare
Authors: Lee, J.; Gary, D. E.; Gallagher, P. T.
2000SPD....31.0250L Altcode: 2000BAAS...32..820L
A powerful flare (GOES SX class of M9.8) occurred on 1999 August 20 at
23:06 UT near the eastern limb during a Max Millennium campaign. The
Owens Valley Solar Array (OVSA) at the time was operating in a high
time resolution (1 s) mode to observe an impulsive microwave burst
rising very rapidly (within 3 s) at all observing frequencies in the
range of 1.4 to 18 GHz. As a main characteristic of the burst, the
microwave spectrum decays in a remarkably well-defined exponential
profile with a timescale varying in the range of ~ 30 s to ~ 4 min,
in proportion to the wavelength. The accompanying hard X ray emission
from the BATSE DISCLA data is confined to a short time interval ( ~ 30
s), and its light curve is very similar to that of the high-frequency
(15--18 GHz) microwaves. Our analysis is therefore focused on whether
these observartions are consistent with theoretical predictions
for the microwave emission from trapped electrons in the corona and
thick target X-ray emission from the electrons precipitating into
the chromosphere. In addition, we infer the magnetic reconnection
geometry from EUV images obtained from SoHO/EIT which is used as
another constraint to study the property of the acceleration. The OVSA
is supported by NSF grants ATM-9796213 and AST-9796238 and NASA grant
NAG5-6381 to New Jersey Institute of Technology.

---------------------------------------------------------
Title: First Results from the Upgraded Owens Valley Solar Array
Authors: Gary, D. E.; Hurford, G. J.; Lee, Jeongwoo; Gallagher, P. T.
2000SPD....31.0244G Altcode:
The Owens Valley Solar Array (OVSA) has undergone extensive hardware
and software upgrades in preparation for the current solar maximum
and the launch of HESSI. We present an overview of the now completed
upgrade from 5 to 6 antennas, and show first results from the newly
expanded instrument. We show results from several recent flares,
as well as multi-frequency maps of active region coronal structure,
to demonstrate the improvements now possible with the instrument. The
data and analysis software are freely available on the web, and we
invite all who are interested in working with these data to contact
the associated website.

---------------------------------------------------------
Title: SECIS: The Solar Eclipse Coronal Eclipse Imaging System
Authors: Phillips, K. J. H.; Read, P. D.; Gallagher, P. T.; Keenan,
F. P.; Rudawy, P.; Rompolt, B.; Berlicki, A.; Buczylko, A.; Diego,
F.; Barnsley, R.; Smartt, R. N.; Pasachoff, J. M.; Babcock, B. A.
2000SoPh..193..259P Altcode:
The Solar Eclipse Coronal Imaging System (SECIS) is an instrument
designed to search for short-period modulations in the solar corona
seen either during a total eclipse or with a coronagraph. The CCD
cameras used in SECIS have the capability of imaging the corona at a
rate of up to 70 frames a second, with the intensities in each pixel
digitised in 12-bit levels. The data are captured and stored on a
modified PC. With suitable optics it is thus possible to search for
fast changes or short-period wave motions in the corona that will
have important implications for the coronal heating mechanism. The
equipment has been successfully tested using the Evans Solar Facility
coronagraph at National Solar Observatory/Sacramento Peak and during
the 11 August 1999 eclipse at a site in north-eastern Bulgaria. The
instrument is described and preliminary results are outlined.

---------------------------------------------------------
Title: Optical and EUV Observations of the Solar Atmosphere
Authors: Gallagher, P. T.
2000PhDT.........2G Altcode:
This thesis presents the results of optical and EUV observations of
the solar atmosphere ranging in height from the photosphere to the
corona. In the first sections, the morphology and dynamics of the
photosphere, chromosphere, transition region and corona are studied
with the Coronal Diagnostic Spectrometer (CDS) and the Michelson
Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory
(SOHO). These results are compared to, and found to be consistent with,
current solar atmospheric models. We also use the density sensitive
Si IX (349.9 A/341.9 A) and Si X (356.0 A/347.7 A) line ratios,
observed with CDS, to study the radial and angular variation of
electron density in the corona. These observations are found to agree
extremely well with recent magnetohydrodynamical models of the corona
and solar wind. The design and testing of the Solar Eclipse Coronal
Imaging System (SECIS) is also described in the final section. This
instrument was designed to search for short-period modulations in the
Fe XIV (5303 A) solar corona seen either during a total eclipse or
with a coronagraph. Initial results from SECIS observing programs at
the John W. Evans Solar Facility coronagraph in New Mexico, and from
the 1999 August 11 total solar eclipse are also discussed.

---------------------------------------------------------
Title: OVRO Solar Array Analysis Software in Support of HESSI
Authors: Gallagher, P. T.; Gary, D. E.; Lee, J.
2000ASPC..206..363G Altcode: 2000hesp.conf..363G
No abstract at ADS

---------------------------------------------------------
Title: The Quiet Sun Atmosphere as Seen by Soho
Authors: Phillips, K. J. H.; Gallagher, P. T.; Harra-Murnion, L. K.;
Keenan, F. P.; Pres, P.
2000AdSpR..25.1747P Altcode:
The recent solar minimum has allowed studies to be made of quiet-Sun
structures with SOHO instruments with better resolution than
before. This paper reports on the morphology and dynamics of the EUV
emission, including the chromospheric and transition-region network
and coronal features, and how the photospheric magnetic field and
coronal bright points are related

---------------------------------------------------------
Title: A New Study of the Quiet Sun
Authors: O'Shea, E.; Gallagher, P. T.; Mathioudakis, M.; Phillips,
K. J. H.; Keenan, F. P.
1999ESASP.446..519O Altcode: 1999soho....8..519O
In this paper we present results of an emission measure analysis
performed on regions of cell, network and bright network emission
which were observed in the quiet Sun at Sun centre with the Coronal
Diagnostic Spectrometer (CDS) on board SOHO. Seperate emission from
the three regions was obtained by a method of image segmentation
using a histogram modification technique. From the averaged emission
it was possible to produce emission measures over a broad temperature
range. These emission measures were then used to produce estimates of
radiative and conductive losses in the three regions considered. Using
a magnetogram obtained from the MDI instrument on SOHO we show that
the bright network emission originates from bipolar magnetic loops
and from what appear to be monopole regions, which could be the
remains of footpoints of larger loops. The bright network emission
shows significantly higher mean magnetic field strength as well as
significantly larger radiative energy losses than either of the other
two regions. We find some evidence suggesting the presence of cool
loops. The process of image segmentation also enabled us to obtain
the relative areas of the cell, network and bright network emission
as a function of temperature. We found that only the bright network
emission showed an expansion in area with temperature and therefore
height. Fitting this area curve with the functional form suggested
by Rabin (1991),i.e A(T)/A(Th) = [1 + (Gamma2
- 1)(T/Th)nu]1/2/Gamma , for the
cross-sectional area of a flux tube, we obtain a value of Gamma=7.1
and nu=2.5 for the constriction and shape factors respectively.

---------------------------------------------------------
Title: The Radial and Angular Variation of the Electron Density in
the Solar Corona
Authors: Gallagher, P. T.; Mathioudakis, M.; Keenan, F. P.; Phillips,
K. J. H.; Tsinganos, K.
1999ApJ...524L.133G Altcode:
We derive, for the first time, electron densities as a function
of both radius (R) and position angle (θ) for the southwest
quadrant of the off-limb corona, using the density-sensitive Si IX
λ349.9/λ341.9 and Si X λ356.0/λ347.7 extreme-ultraviolet line
ratios. The observations were made with the coronal diagnostic
spectrometer on board the Solar and Heliospheric Observatory over
the ranges of 1.00 Rsolar&lt;R&lt;1.20 Rsolar
and 180deg&lt;θ&lt;270deg. Within the south
polar coronal hole, the density varies from 2.3×108
cm-3 at 1.0 Rsolar to 8.3×107
cm-3 at 1.20 Rsolar, while at the equator,
the density varies from 6.3×108 cm-3 at 1.0
Rsolar to 1.6×108 cm-3 at 1.20
Rsolar. The density falloff with height is therefore faster
in the equatorial region. We also find that electron densities are,
on average, a factor of 2.7 larger in the equatorial regions than in
the polar coronal hole at a given radial distance. Finally, we find
remarkable agreement between our measured densities as a function of
radius and position angle and those predicted by a recent analytic
MHD model of the solar wind, strongly supporting its basic premises.

---------------------------------------------------------
Title: Transient events in the EUV transition region and chromosphere
Authors: Gallagher, P. T.; Phillips, K. J. H.; Harra-Murnion, L. K.;
Baudin, F.; Keenan, F. P.
1999A&A...348..251G Altcode:
Rapid time cadence observations of the quiet Sun extreme
ultraviolet emission, observed by the cds instrument on soho, are
discussed. Numerous transient brightenings are observed in network
features in both a transition region line (O V 629.73 Ä) and a
chromospheric line (He I 584.33 Ä), indicating a dynamic coupling
between the chromospheric and transition region network. Their
durations are between 80 and 200 s and dimensions 6 000-10 000 km. A
wavelet analysis reveals a tendency for semi-periodic behaviour,
with excess power at a frequency of about 4 mHz. The variations are
much less evident in the internetwork or cell regions, although they
are again semi-periodic. Relative line-of-sight velocities have also
been derived from the data, the cds spectral resolution allowing a
precision of between 4.7 and 6 km s(-1) . There is a clear association
of brightenings in the network with downflows of ~ 13 km s(-1) at 250
000 K with some events having velocities of up to ~ 20 km s(-1) , these
being measured relative to the average quiet Sun emission. Within the
internetwork, we also find a weak correlation between events seen in
the He I (584.33 Ä) and the O V (629.73 Ä) lines. In this case, the
events have a smaller size (&lt;= 2 000 km), amplitude (both in terms of
their intensity and velocity), and also show a higher frequency of about
6 mHz. The apparent differing properties of network and internetwork
events implies that both these regions are heated by two distinct
mechanisms. In the case of the internetwork, these results further
confirm that acoustic waves propagating up from the photosphere and
forming shocks in the overlying atmosphere are the most likely heating
mechanism. For the network, it is apparent that the heating required
must be in excess of that supplied by acoustic shocks. Our view is that
the network events are produced by nanoflare-like magnetic reconnections
in the corona, or possibly excitation due to a spicule-type event in
which there is a repeated rebound.

---------------------------------------------------------
Title: Book Review: The sun in eclipse / Springer, 1997 &amp; 1998
Authors: Gallagher, P. T.; Keenan, F. P.; Phillips, K. J. H.; Read,
P. D.; Rudawy, P.; Mpolt, B. Ro
1999IrAJ...26..115G Altcode:
The Solar Eclipse Coronal Imaging System (SECIS) is an instrument
designed to search for short-period modulations in the solar corona seen
either during a total eclipse or with a coronagraph. The CCD cameras
used in SECIS have the capability of imaging a selected portion of the
corona at a rate of 50 frames per second, with the intensities in each
pixel digitised in 12-bit levels. The data are captured and stored on
a modified PC. It will thus be possible to search for fast changes
or short-period wave motions in the corona that will have important
implications for the coronal heating mechanism. Tests have been
carried out during the 1998 total solar eclipse visible in Guadeloupe
(French West Indies) and with the Evans Solar Facility coronagraph at
the National Solar Observatory, Sacramento Peak, with scientifically
useful results obtained from the latter.

---------------------------------------------------------
Title: Quiet Sun Bright Point Dynamics and Energetics as seen by
SOHO and Yohkoh
Authors: Gallagher, P.; Keenan, F.; Phillips, K.; Prés, P.;
Harra-Murnion, L.
1999ASPC..183..405G Altcode: 1999hrsp.conf..405G
No abstract at ADS

---------------------------------------------------------
Title: Properties of the quiet Sun EUV network
Authors: Gallagher, P. T.; Phillips, K. J. H.; Harra-Murnion, L. K.;
Keenan, F. P.
1998A&A...335..733G Altcode:
Observations of the quiet Sun network in a small region at Sun
centre taken with the Coronal Diagnostic Spectrometer (CDS) on board
SOHO are reported for EUV lines with T_e between ~ 10(4) and 10(6)
K. The changing structure of the network in the upper chromosphere,
transition region, up to the corona was examined using intensity
distributions which were decomposed into two normal components using
a mixture-modelling technique. This enabled areas of high and low
intensities to be separated, and hence averaged network properties
including area, intensity, contrast, and fractal dimension to
be derived as a function of ion temperature. The network area and
emission were found to be more concentrated in the transition region
than in the chromosphere and in the corona, although the results
for the chromospheric He lines appear to be affected by resonance
scattering. At ~ 10(6) K, the area and emission of bright structures
dramatically increase, partly due to the appearance of small coronal
loops. There is also a discrete change in the fractal dimension at
coronal temperatures, signifying a change from network to simpler
coronal structures. Furthermore, the contrast of bright to dark regions
is at a maximum for T_e ~ 2.5x 10(5) K and falls to its lowest values
for coronal temperatures. The properties of several individual network
structures were found to follow the same general behaviour as in
the statistical analysis. Our results including physical dimensions
are broadly consistent with the transition region model of Gabriel,
although we cannot exclude the existence of low-lying loops as in the
model of Dowdy et al.

---------------------------------------------------------
Title: CDS observations of the quiet Sun EUV network
Authors: Gallagher, P. T.; Phillips, K. J. H.; Harra-Murnion, L. K.;
Keenan, F. P.
1998ESASP.421..365G Altcode: 1998sjcp.conf..365G
No abstract at ADS

---------------------------------------------------------
Title: The Structural Variability of the Solar EUV Network
Authors: Gallagher, P. T.; Phillips, K. J. H.; Harra-Murnion, L. K.;
Keenan, F. P.
1998ASPC..154..612G Altcode: 1998csss...10..612G
Observations of the quiet Sun with the Coronal Diagnostic Spectrometer
(CDS) on board the Solar and Heliospheric Observatory (SOHO) are
reported for the upper chromosphere, transition region, and corona. The
changing structure of the EUV network is examined over a temperature
range of 1.5 x 10^4 K to 1.2 x 10^6 K using a variety of properties
of the characteristic intensity distributions. The distribution of
intensity in small (4 x 4 arcmins^2) areas of the quiet Sun at Sun
centre has been examined. These distributions were found to consist of
both a low intensity core distribution combined with an extended tail
associated with the transition region EUV network. Network properties
such as relative area, emission, contrast, and fractal dimension
have been derived by fitting two Gaussians (one representing the cell
distribution, the other the network) to each frequency histogram and
then using the cross-over point of the two Gaussians as a boundary
point between the two components. The integrity of the network displays
a well defined relationship with temperature showing a noticeable
structural enhancement in the temperature range 1.1 x 10^5 K to 2.5 x
10^5 K together with a dramatic change in integrity at coronal (&gt;=
10^6 K) temperatures.

---------------------------------------------------------
Title: CDS Observations of the Quiet Sun EUV Network
Authors: Gallagher, P. T.; Phillips, K. J. H.; Harra-Murnion, L. K.;
Keenan, F. P.
1997ESASP.404..395G Altcode: 1997cswn.conf..395G
No abstract at ADS