Author name code: thompson-barbara
ADS astronomy entries on 2022-09-14
author:"Thompson, Barbara J."
------------------------------------------------------------------------
Title: Defining the Middle Corona
Authors: West, Matthew J.; Seaton, Daniel B.; Wexler, David B.;
Raymond, John C.; Del Zanna, Giulio; Rivera, Yeimy J.; Kobelski,
Adam R.; DeForest, Craig; Golub, Leon; Caspi, Amir; Gilly, Chris R.;
Kooi, Jason E.; Alterman, Benjamin L.; Alzate, Nathalia; Banerjee,
Dipankar; Berghmans, David; Chen, Bin; Chitta, Lakshmi Pradeep; Downs,
Cooper; Giordano, Silvio; Higginson, Aleida; Howard, Russel A.; Mason,
Emily; Mason, James P.; Meyer, Karen A.; Nykyri, Katariina; Rachmeler,
Laurel; Reardon, Kevin P.; Reeves, Katharine K.; Savage, Sabrina;
Thompson, Barbara J.; Van Kooten, Samuel J.; Viall, Nicholeen M.;
Vourlidas, Angelos
Bibcode: 2022arXiv220804485W
Altcode:
The middle corona, the region roughly spanning heliocentric altitudes
from $1.5$ to $6\,R_\odot$, encompasses almost all of the influential
physical transitions and processes that govern the behavior of
coronal outflow into the heliosphere. Eruptions that could disrupt
the near-Earth environment propagate through it. Importantly, it
modulates inflow from above that can drive dynamic changes at lower
heights in the inner corona. Consequently, this region is essential
for comprehensively connecting the corona to the heliosphere and for
developing corresponding global models. Nonetheless, because it is
challenging to observe, the middle corona has been poorly studied by
major solar remote sensing missions and instruments, extending back to
the Solar and Heliospheric Observatory (SoHO) era. Thanks to recent
advances in instrumentation, observational processing techniques,
and a realization of the importance of the region, interest in the
middle corona has increased. Although the region cannot be intrinsically
separated from other regions of the solar atmosphere, there has emerged
a need to define the region in terms of its location and extension
in the solar atmosphere, its composition, the physical transitions
it covers, and the underlying physics believed to be encapsulated by
the region. This paper aims to define the middle corona and give an
overview of the processes that occur there.
Title: Remote Sensing of Coronal Forces during a Solar Prominence
Eruption
Authors: Uritsky, V. M.; Thompson, B. J.; DeVore, C. R.
Bibcode: 2022ApJ...935...47U
Altcode: 2022arXiv220502344U
We present a new methodology-the Keplerian Optical Dynamics Analysis
(KODA)-for quantifying the dynamics of erupting magnetic structures
in the solar corona. The technique involves adaptive spatiotemporal
tracking of propagating intensity gradients and their characterization
in terms of time-evolving Keplerian areas swept out by the position
vectors of moving plasma blobs. Whereas gravity induces purely ballistic
motions consistent with Kepler's second law, noncentral forces such as
the Lorentz force introduce nonzero torques resulting in more complex
motions. KODA algorithms enable direct evaluation of the line-of-sight
component of the net torque density from the image-plane projection
of the areal acceleration. The method is applied to the prominence
eruption of 2011 June 7, observed by the Solar Dynamics Observatory's
Atmospheric Imaging Assembly. Results obtained include quantitative
estimates of the magnetic forces, field intensities, and blob masses
and energies across a vast region impacted by the postreconnection
redistribution of the prominence material. The magnetic pressure
and energy are strongly dominant during the early, rising phase of
the eruption, while the dynamic pressure and kinetic energy become
significant contributors during the subsequent falling phases. Measured
intensive properties of the prominence blobs are consistent with those
of typical active-region prominences; measured extensive properties
are compared with those of the whole pre-eruption prominence and the
post-eruption coronal mass ejection of 2011 June 7, all derived by
other investigators and techniques. We show that KODA provides valuable
information on spatially and temporally dependent characteristics of
coronal eruptions that is not readily available via alternative means,
thereby shedding new light on the environment and evolution of these
solar events.
Title: Science Autonomy for Ocean Worlds Astrobiology: A Perspective
Authors: Theiling, Bethany P.; Chou, Luoth; Da Poian, Victoria;
Battler, Melissa; Raimalwala, Kaizad; Arevalo, Ricardo, Jr.; Neveu,
Marc; Ni, Ziqin; Graham, Heather; Elsila, Jamie; Thompson, Barbara
Bibcode: 2022AsBio..22..901T
Altcode:
No abstract at ADS
Title: The Solaris Solar Polar MIDEX-Class Mission Concept: Revealing
the Mysteries of the Sun's Poles
Authors: Hassler, Donald M.; Harra, Louise K.; Gibson, Sarah; Thompson,
Barbara; Gusain, Sanjay; Berghmans, David; Linker, Jon; Basu, Sarbani;
Featherstone, Nicholas; Hoeksema, J. Todd; Viall, Nicholeen; Newmark,
Jeffrey; Munoz-Jaramillo, Andres; Upton, Lisa A.
Bibcode: 2022cosp...44.1528H
Altcode:
Solaris is an exciting, innovative & bold mission of discovery to
reveal the mysteries of the Sun's poles. Solaris was selected for Phase
A development as part of NASA's MIDEX program. Solaris builds upon
the legacy of Ulysses, which flew over the solar poles, but Solaris
provides an entirely new feature remote sensing, or IMAGING. Solaris
will be the first mission to image the poles of the Sun from ~75
degrees latitude and provide new insight into the workings of the
solar dynamo and the solar cycle, which are at the foundation of our
understanding of space weather and space climate. Solaris will also
provide enabling observations for improved space weather research,
modeling and prediction with time series of polar magnetograms and
views of the ecliptic from above, providing a unique view of the
corona, coronal dynamics, and CME eruption. To reach the Sun's poles,
Solaris will first travel to Jupiter, and use Jupiter's gravity to
slingshot out of the ecliptic plane, and fly over the Sun's poles
at ~75 degrees latitude. Just as our understanding of Jupiter &
Saturn were revolutionized by polar observations from Juno and Cassini,
our understanding of the Sun will be revolutionized by Solaris.
Title: Developing a vision for maturing the Heliophysics
infrastructure towards open science: The LIKED online resource and
the DIARieS analysis ecosystem.
Authors: Ringuette, Rebecca; Thompson, Barbara; Mcgranaghan, Ryan;
Engell, Alexander; Gerland, Oliver
Bibcode: 2022cosp...44.3521R
Altcode:
The Heliophysics infrastructure is filled with a plethora of useful
resources such as data archives, software packages, analysis tutorials,
educational resources, related publications, and the people involved
in developing these resources. However, these resources are not
interlinked or interoperable, presenting a problematic barrier for
progress towards open science in Heliophysics. We summarize a vision
to address these barriers using currently available modern technology
and techniques resulting in two new infrastructure components: LIKED,
a LIbrary KnowledgE and Discovery (LIKED) online resource for finding
and accessing knowledge and infrastructure resources; and DIARieS, an
analysis ecosystem to simplify Discovery, Implementation, Analysis,
Reproducibility, and Sharing (DIARieS) of scientific results and
environments. LIKED addresses the findability and accessibility
barriers for Heliophysics resources by building upon the successes
of Wikipedia and the technologies supporting internet search engines
(e.g. Google). DIARieS builds upon the new capabilities that will be
possible through LIKED and various modern technologies (e.g. Kubernetes
clusters and containerization) combined with innovative ideas to
offer a viable solution for open science, including interoperability,
reproducibility, and interactive dissemination. The creation of these
new infrastructure elements requires coordination between various
members and groups in the Heliophysics and related communities. We thus
request feedback from the extended COSPAR community on this vision,
and point those interested to the two related papers submitted to the
2022 COSPAR Space Weather Roadmap.
Title: Exploring Structures and Flows with NASA's under-construction
PUNCH mission
Authors: DeForest, Craig; Gibson, Sarah; Thompson, Barbara;
Malanushenko, Anna; Desai, Mihir; Elliott, Heather; Viall, Nicholeen;
Cranmer, Steven; de Koning, Curt
Bibcode: 2022cosp...44.1077D
Altcode:
The Polarimeter to UNify the Corona and Heliosphere is a NASA Small
Explorer to image the corona and heliosphere as parts of a single
system. PUNCH comprises four ~50kg smallsats, each carrying one imaging
instrument, that work together to form a single "virtual coronagraph"
with a 90° field of view, centered on the Sun. Scheduled for joint
launch with NASA's SPHEREx mission, PUNCH starts its two-year prime
science phase in 2025. PUNCH will generate full polarized image
sequences of Thomson-scattered light from free electrons in the corona
and young solar wind, once every four minutes continuously. This
enables tracking the young solar wind and turbulent structures within
it as they disconnect from the Sun itself, as well as large transients
such as CMEs, CIRs, and other shocks within the young solar wind. A
student-contributed X-ray spectrometer (STEAM) will address questions
of coronal heating and flare physics. We present motivating science,
expected advances, mission status, and how to get involved with PUNCH
science now.
Title: Connecting the Sun/Corona/Heliosphere Through the Combination
of Remote Sensing Data Products and PSP Observations
Authors: Alzate, Nathalia; Nieves-Chinchilla, Teresa; Thompson,
Barbara; Di Matteo, Simone; Morgan, Huw; Seaton, Daniel
Bibcode: 2022cosp...44.1349A
Altcode:
Understanding the Sun/Corona/Heliosphere system requires effectively
establishing a link between in situ measurements and remote observations
by characterizing structure and plasma properties of the inner
corona. Additionally, we need to resolve the line-of-sight (LOS)
limitations of coronagraph and EUV observations to properly identify
the location of structures and their temporal density changes. Our
advanced image processing techniques can reveal structures (on various
timescales) in both EUV and visible-light data providing continuous
tracking of brightness enhancements from the coronal base out to the
radial extended corona. Our most recent work using STEREO/COR1 and
GOES-R/SUVI has proven crucial in linking the low to high corona and has
facilitated the interpretation of PSP data. Further, our time-dependent
rotational tomography of coronal data yields empirically derived
coronal density distribution directly comparable to PSP measurements
at perihelion. We present our current work that combines PSP data
with RS EUV/WL observations of the corona, via the use of coronal
rotational tomography from SOHO/LASCO and STEREO/COR2 observations,
which provides the capabilities to reconstruct features in the solar
wind and subsequently study the evolution between EUV/WL and in situ
of the plasma flows that give rise to them.
Title: Solar Energetic Particle (SEP) events forecasting in the
framework of SPRINTS
Authors: Engell, Alexander; Thompson, Barbara; Richardson, Ian G.;
Dayeh, Maher; Falconer, David
Bibcode: 2022cosp...44.1147E
Altcode:
We present the Space Radiation Intelligence System (SPRINTS) and its
current capabilities to forecast solar energetic particles (SEP) using
streamlined data-driven and machine-learning processes. SPRINTS is
designed as a community ecosystem to ensure scientific transparency and
can be deployed to any infrastructure environment. Its current data is
comprised of GOES X-ray and proton data from 1986-present and ACE/DSCOVR
from 1997-present in a Timescale database with APIs. The time-series
database is supported by flare, SEP, and CME event catalogs as well as
event associated catalogs such as flares associated with SEPs, CMEs and
radio bursts. Within the framework of SPRINTS, these catalogs can be
improved through scientific crowd-sourcing methods (e.g., versioning)
thereby allowing critical alignment of both underlying data and event
relationships. This forms a ML-ready dataset process for the community
interested in establishing consistent train, test and validation and
verification processes when building models to predict flares, SEPs,
and CMEs. SPRINTS is coupled to the MagPy (i.e., MAG4) forecasting
capability whereby it takes probabilistic forecast parameters of
interest based on free-energy proxies for flare parameters including
flare flux, fluence and peak ratio of the long and short X-ray channels
required by the post-eruptive machine-learned models developed. This
gives a continuous pre- and post-eruptive forecasting capability as new
information (e.g., flare eruptions and CME kinematic) becomes available
to the system. We will present initial models results for the Air
Force Research Laboratory SEP forecast requirements (10 MeV @ 10 pfu,
10 MeV @40 pfu, 30 MeV @10 pfu, 50 MeV @10 pfu, 100 MeV @ 1 pfu) at 12
hour and 24 hour cadences. SPRINTS is currently providing forecasts in
real-time through a REST API and has supporting dashboards near-real
time forecasts, historical analysis, and event relationship analysis.
Title: Expected results for the cradle of the Solar Wind with the
Polarimeter to UNify the Corona and Heliosphere (PUNCH)
Authors: DeForest, Craig; Gibson, Sarah; De Koning, Curt A.; Thompson,
Barbara; Malanushenko, Anna; Desai, Mihir; Elliott, Heather; Viall,
Nicholeen; Cranmer, Steven
Bibcode: 2022cosp...44.1324D
Altcode:
The Polarimeter to UNify the Corona and Heliosphere is a NASA Small
Explorer to image the corona and heliosphere as parts of a single
system. Imaging the corona and heliosphere together from a constellation
of four synchronized smallsats, PUNCH will — starting in 2025 —
provide a unique window on global structure and cross-scale processes
in the outer corona and young solar wind. PUNCH science is informed
by, and complements, the results of PSP and Solar Orbiter; and will
synergize with PROBA3/ASPIICS. We present early prototype results from
STEREO/SECCHI and current preparation work to enable PUNCH science
when data arrive, discuss anticipated results from the deeper-field,
higher time resolution imaging that PUNCH will provide, and describe
how to get involved with PUNCH science now.
Title: Facilitating Heliophysics Data Discovery with Cloud
Collaboration: Development for the HSO Connect Program
Authors: Alshatnawi, Amr; Thompson, Barbara; Ireland, Jack; Roberts,
D. Aaron; Damas, M. Chantale
Bibcode: 2021AGUFMSA15B1930A
Altcode:
The HSO (Heliophysics System Observatory) Connect programs goal is to
link the Heliophysics community together, and establish a connection for
collaboration and data sharing. It is often difficult for researchers to
share data and also find new resources, which leads many of them to use
a specific data set or resource for most of their research. Since there
are numerous data sources, developing an environment for data sharing
is very beneficial as it will allow scientists to reach different data
more easily and efficiently. The focus of this project was to develop
and test different cloud collaboration environments. To achieve this
the NASA Amazon Web Services cloud was used by the HelioAnalytics
team for collaboration on code development. This cloud allowed the
development of the Heliophysics JupyterHub, which was used to create
Jupyter notebooks that researched multiple instances of data and model
products from different missions. JupyterHub also allows users to
configure their environment, so they can access and request different
data. In order to share these notebooks and data, a GitHub site was
created for the HSO Connect project. The objective of the GitHub site
is to facilitate data resources and code sharing. This site will also
contain different data models, tools, and services that will support
the goal of the program. Developing and using these different cloud
collaboration tools will provide a more efficient and simple way to
access and share data, it will also improve code development as it will
allow participants to share along with work on each others code. The
outcome achieved from using these cloud collaboration tools will help
connect observations from HSO missions with other observations from
different Science Mission Directorate missions.
Title: Report on a Workshop to Understand Heliophysics Research
Infrastructure
Authors: Thomas, Brian; Candey, Robert; Fung, Shing; Ireland, Jack;
Jian, Lan; Kirk, Michael; Kuznetsova, Maria; McGranaghan, Ryan;
Roberts, D. Aaron; Thompson, Barbara
Bibcode: 2021AGUFMSH44C..01T
Altcode:
We report observations and findings from a three-day virtual workshop
on heliophysics research infrastructure. The workshop, held on May
17-19, 2021, was organized by the NASA Goddard Space Flight Center
to examine the current NASA heliophysics research infrastructure
and determine which elements were most utilized, what gaps exist in
these elements between current utility and desired capability and,
from a user standpoint, what a future state for the infrastructure
might look like. Approximately 40 subject matter experts (SMEs)
with backgrounds in heliophysics research, computer science and
research infrastructure were gathered to consider these topics. Key
gaps identified include enhancements to science data products,
improved support for collaboration and open science, and a need for
more sophisticated information discovery. We will discuss these gaps
and how they connect to the participants imagined future state which
emphasizes a faster ability to get to the good stuff by improved
service delivery and infrastructure support.
Title: Towards a Coherent View of the Sun/Corona/Heliosphere:
Combining Remote Sensing Data Products with PSP In Situ Measurements
Authors: Alzate, Nathalia; Morgan, Huw; Seaton, Daniel; Thompson,
Barbara; Nieves-Chinchilla, Teresa; Di Matteo, Simone; Viall, Nicholeen
Bibcode: 2021AGUFMSH24C..02A
Altcode:
In situ (IS) heliospheric measurements and remote sensing
observations contribute crucial information to our understanding of
the Sun/Corona/Heliosphere as a single system. In Situ measurements by,
e.g., Parker Solar Probe (PSP), are detailed and precise measurements of
physical observables (e.g., magnetic field components), which cannot
be gained from remote observations. Remote sensing observations,
in turn, provide the large-scale context, which is absent from
the in situ data taken at one point in space. Therefore, to
understand the Sun/Corona/Heliosphere system, we need to effectively
establish a link between in situ measurements and remote sensing
observations by characterizing structure and plasma properties of
the inner corona. Additionally, we need to resolve the line-of-sight
limitations of white-light (WL) coronagraph and Extreme Ultraviolet
(EUV) observations to properly identify the location of structures and
their temporal density changes. Previous studies have identified outward
propagating density variations in the solar wind (on timescales of hours
up to ~3 days) that have a plasma composition of coronal origin and that
can be traced down through the field of view of STEREO/COR2 (~2.5-15
Rs). Our advanced image processing techniques can reveal structures
(on various timescales) in both EUV and WL data providing continuous
tracking of brightness enhancements from the coronal base out to the
radial extended corona. Our most recent work using STEREO/COR1 and
GOES-R/SUVI observations has proven crucial in linking the low to high
corona and has facilitated the interpretation of PSP data. Further, our
time-dependent rotational tomography of coronal data yields empirically
derived coronal density distribution directly comparable to PSP
measurements at perihelion. We present our current work that combines
PSP data with remote sensing EUV/WL observations of the corona, via the
use of coronal rotational tomography from SOHO/LASCO and STEREO/COR2
observations, which provides the capabilities to reconstruct features
in the solar wind and subsequently study the evolution between EUV/WL
and in situ of the plasma flows that give rise to them.
Title: Heliophysics: A small field with big data science
Authors: Thompson, Barbara; Bard, Christopher; Dorelli, John;
McGranaghan, Ryan; Kirk, Michael; Narock, Ayris
Bibcode: 2021AGUFM.U51B..01T
Altcode:
Heliophysics is a relatively small community, compared to other NASA
Science Divisions (Astrophysics, Planetary, and Earth Science). However,
Heliophysics has cross-cutting cross-disciplinary relationships that
easily connect to, and are applied to, all of other science domains. To
start, the Sun is a typical astrophysical object. It is a rotating
sphere with an extended atmosphere, it exhibits seasons and islands
of activity, and there are local processes that strongly couple to
global dynamics; this connects well to many problems in the Earth
Sciences. Also, the Suns atmosphere extends to form the heliosphere,
drives processes and interacts with all of the planetary environments,
and reaches to the heliopause and interstellar medium. Additionally,
Heliophysics relies on a wide variety of instrumentation: In
situ, remote sensing, spectroscopy, as well as constellation &
multi-viewpoint observatories. The field is faced with common data
science challenges, such as: (1) Multi-domain, multi-variate processes
(2) Wide range of scales: temporal, spatial, energetic, spectral,
etc. (3) Forecasting, data assimilation, operational modeling. Though
relatively new, Heliophysics is a well-developed community with strong
roots that can support strong branches. Our ability to connect means
that we can benefit from other areas, and vice versa. By emphasizing
cross-disciplinary collaboration and resource development, we can form
a foundation for Open Science across multiple research domains.
Title: Early Results from Whole Heliosphere Planetary Interactions
(WHPI) Campaigns
Authors: Thompson, Barbara; Allen, Robert; de Toma, Giuliana; Gibson,
Sarah; Qian, Liying
Bibcode: 2021AGUFMSH11A..03T
Altcode:
The Whole Heliosphere and Planetary Interactions (WHPI) is an
international initiative focused around the solar minimum period that
aims to understand the interconnected sun-heliospheric-planetary system,
by facilitating and encouraging interdisciplinary activities. Particular
WHPI science foci include the global connected structure of the
heliosphere and planetary space environments/atmospheres, the
origins and impacts of high-speed solar wind streams, CMEs from
sun-to-heliopause, and comparative solar minima. This is achieved
through a series of coordinated observing campaigns, including Parker
Solar Probe perihelia, and virtual interactions including a dedicated
workshop where observers and modelers get together to discuss, compare,
and combine research results. We present a summary of the outcomes and
activities of the WHPI science workshop held September 13-17, 2021,
and an update on the repository of data (observations and models,
Sun to solar wind to planets) that have been gathered.
Title: SynCOM: Synthetic Corona Outflow Model for the Heliophysics
community
Authors: Moraes Filho, Valmir; Uritsky, Vadim; Thompson, Barbara;
DeForest, Craig
Bibcode: 2021AGUFMSH24C..06M
Altcode:
Numerous methods for measuring coronal flow velocities have been
developed over the years. These measurements are central to our
understanding of the origin of the solar wind and serving to upcoming
missions that address this problem, such as the Polarimeter to Unify the
Corona and Heliosphere (PUNCH) mission. However, many of the existing
flow tracking methods provide qualitatively reasonable outcomes, their
quantitative validation across the wide range of coronal altitudes
remains a problem. The lack of precise knowledge about the targeted
velocity field is the primary obstacle, making it impossible to compare
algorithms attempting to estimate flow parameters for the same coronal
structure. To address this problem, we are designing the Synthetic
Corona Outflow Model (SynCOM) an empirical data-driven model of a
dynamic solar corona based on previous high-resolution observations. The
SynCOM model mimics the transient and quasi-periodical behavior present
in the actual solar corona, such as the one observed by STEREO-A/COR
2. The SynCOM outputs exhibit a true-to-life radial decay of the
polarized brightness and include stochastic components accounting for
physical fluctuations of plasma outflows and instrumental noise. Since
the model has a predefined distribution of flow velocity and an
adjustable signal-to-noise ratio, it can be used for testing a variety
of data analysis methods used to measure coronal flows. Adjusting SynCOM
settings for specific coronal conditions and instrumental parameters
enables a straightforward comparison of accuracy and performance of
different data analysis methods and measurement techniques designed
to quantify velocity and acceleration in the corona. In this work,
we will present examples of the application of SynCOM for verifying
observational requirements for detecting coronal flows beyond the
range of altitudes covered by previously operated coronagraphs; and
benchmarking popular flow tracking codes used by the coronal physics
community, and cross-validating their outputs.
Title: Acceleration in the Low Corona of CMEs Associated with Solar
Energetic Particle Events
Authors: St Cyr, O.; Richardson, Ian; Thompson, Barbara; Burkepile,
Joan; Balmaceda, Laura; Fry, Dan; Parker, Linda
Bibcode: 2021AGUFMSH55F1914S
Altcode:
We report here on the initial accelerations of coronal mass ejections
(CMEs) associated with 25 MeV solar energetic proton events (SEPs)
during the period 1980-2017. Primary CME observations in the low corona
were obtained at Mauna Loa Solar Observatory (MLSO) and, where possible,
they were combined with spacebased observations from the SMM C/P,
P78-1 Solwind, and SOHO LASCO coronagraphs. We identified >100
SEPs with associated MLSO observations of CMEs, and we were able to
combine many of those with the spacebased coronagraphs to reveal the
initial and middle-coronal acceleration of the SEP-associated CMEs. We
were able to determine both an instantaneous maximum acceleration as
well as an average acceleration in the low corona. We compare these
measured values with proxy determinations of acceleration and with
their use in predicting SEP properties.
Title: Solar Energetic Particle Events Associated With Coronal Mass
Ejections Observed by the Mauna Loa Solar Observatory
Authors: Richardson, Ian; St Cyr, O.; Burkepile, Joan; Thompson,
Barbara
Bibcode: 2021AGUFMSH55F1910R
Altcode:
Over 100 solar energetic particle (SEP) events including ~25 MeV
protons associated with coronal mass ejections (CMEs) observed by the
Mauna Loa Solar Observatory (MLSO) coronagraphs have been identified
in 1980-2017. These SEP events were detected by instrumentation
on spacecraft such as SOHO, Wind, ACE, IMP 8, ISEE 3, Helios and
Ulysses. They range from three Ground Level Enhancements, also
observed at high energies by neutron monitors, to small events that
are barely evident above the instrumental background, as well as Fe-
or electron-rich or poor events. We summarize the properties of these
SEP events and the associated solar phenomena (e.g., CMEs observed
by MLSO and, if available, spacecraft coronagraphs, flares, radio
emissions) and discuss several examples. We demonstrate how ground-based
coronagraphs can provide an early assessment of the CME parameters prior
to the arrival of particles at Earth. We also discuss whether these CME
parameters are related to the properties of the associated SEP events.
Title: Magnetic Field Curvature In A Filament Channel Derived From
Oscillation Measurements And MHD Modeling
Authors: Kucera, T. A.; Luna, M.; Torok, T.; Muglach, K.; Downs, C.;
Sun, X.; Thompson, B.; Karpen, J.; Gilbert, H.
Bibcode: 2021AAS...23811306K
Altcode:
We have used measurements of repeated large amplitude longitudinal
oscillations (LALOs) in an active region filament to diagnose the
curvature of the magnetic field in the filament channel and compared the
results with predictions of an MHD flux-rope model based on magnetograms
of the region. In May and June of 2014 Active Region 12076 exhibited a
complex of filaments undergoing repeated oscillations over the course
of twelve days. The central filament channel exhibited emerging and then
canceling magnetic flux that resulted in multiple activations, filament
eruptions, and eight oscillation events, which we analyzed using GONG
H-alpha data. Luna and Karpen (2012) model LALOs as oscillations of
magnetized filament plasma moving along dipped magnetic field lines
with gravity as a restoring force. Under this model the period of these
oscillations can be used to estimate the curvature of the magnetic
field in the location of the filament threads. Utilizing this, we find
that the measured periods in the central filament ranging from 34-74
minutes should correspond to magnetic field curvatures of about 30-136
Mm. We also derive radii of curvature for the central filament channel
using a flux-rope model that is based on an SDO/HMI magnetogram of the
region. The rope is constructed using the analytic expressions by Titov
et al. (2018) and then numerically relaxed towards a force-free state in
the zero-beta MHD approximation, where gravity and thermal pressure are
neglected. For comparison, we also employ a nonlinear force-free field
(NLFFF) extrapolation of the active region. We compare the results
of these different ways of attempting to determine the field in the
filament channel.
Title: Non-Robotic Science Autonomy Development
Authors: Theiling, Bethany; Brinckerhoff, William; Castillo-Rogez,
Julie; Chou, Luoth; Da Poian, Victoria; Graham, Heather; Hosseini,
Sona S.; Lyness, Eric; MacKinnon, James; Neveu, Marc; Raimalwala,
Kaizad; Thompson, Barbara
Bibcode: 2021BAAS...53d.048T
Altcode: 2021psad.rept..048T
Non-robotic science autonomy is the ability of an instrument
to analyze its own data for calibration, optimization, and
real-time decision-making, and processing software for rapid data
interpretation. Advancing science autonomy will enhance science return
and enable missions with prohibitive data link rates / time and in
extreme environments.
Title: Solar Flares and Coronal Mass Ejections
Authors: Thompson, Barbara J.; Qiu, Jiong; Lugaz, Noe; Webb, David F.
Bibcode: 2021GMS...258..179T
Altcode:
No abstract at ADS
Title: Information Architecture and Data Utilization: Two Overarching
Clusters Supporting the COSPAR International Space Weather Action Team
(ISWAT) Initiative
Authors: Fung, Shing; Thompson, Barbara; Masson, Arnaud
Bibcode: 2021cosp...43E2394F
Altcode:
Space weather research and forecasting require the availability and
accessibility of pertinent datasets. Depending on the applications:
research analysis, modeling, or space weather forecast operations,
the requirements of data types, data volume, and data sources (e.g.,
real-time data sources, data repositories, or modeling centers), can
be quite different. Different data products, ranging from space-based
and ground-based measurements, to model results, and to event lists or
catalogs, can have diverse organizations and formats. Complexity in
data resources, data types, and measurement or parameter types could
lead to proliferation of services and tools required to search, access,
and analyze the data. The recently inaugurated COSPAR ISWAT initiative
(https://www.iswat-cospar.org/iswat-cospar) aspires to provide a
global hub for collaborations addressing challenges across the field
of space weather, and more generally heliophysics. Among the various
topical clusters, Information Architecture and Data Utilization are two
overarching clusters designed to address effective and efficient data
access and analysis across all ISWAT activities. While Information
Architecture aims to facilitate the development of a global network
of distributed resources for space weather research, analysis,
forecasting and capabilities assessment, Data Utilization focuses
on issues regarding preparation of observational data sets ready for
data assimilation, model validation and utilization as input to data
science algorithms. This presentation describes the various tasks being
pursued by these overarching clusters. With the newest developments in
data science and advancements of machine learning and deep learning, we
will try to identify ways to help make heliophysics and space weather
data more readily and directly usable in data science analysis and
machine learning algorithms.
Title: ISWAT information architecture and data utilization overarching
clusters, a natural follow up of IHDEA
Authors: Masson, Arnaud; De Zeeuw, Darren; Thompson, Barbara; Roberts,
D. Aaron; Arviset, Christophe; De Marchi, Guido; Fung, Shing
Bibcode: 2021cosp...43E2422M
Altcode:
The International Heliophysics Data Environment Alliance (IHDEA) emerged
as a result of the first International Heliophysics Data Environment
(IHDE) meeting held at the European Space and Astronomy Centre (ESAC),
Madrid, Spain, late 2018. Meeting attendees representing NASA, ESA,
JAXA, and CNES have all agreed that increasing collaboration and
coordination through the use of standard formats (for both data and
metadata) and community-based data tools are critical for enabling
interoperability of data systems and services while improving sharing
of space-based, ground-based, and model-based heliophysics data
sets. IHDEA was officially created late 2019 based on a charter and
bylaws agreed by all agencies mentioned above and Nagoya university-ISEE
(https://ihdea.net). It is a collaborative organization whose goal is to
guide the development of a data environment in which the international
heliophysics and space weather research community can seamlessly find,
access, and use all electronically accessible, heliophysics relevant
data sets. The specific mission of the IHDEA is to facilitate global
access to, and exchange of, high quality scientific data products
managed across international boundaries. This will be achieved by
adhering to, and promote the use of, a set of governing metadata
and data standards, data exchange protocols, visualization and data
analysis tools. The role of the IHDEA is to serve as the focal point
to engage the heliophysics data centres and the scientific community,
foster communication, and identify and develop the standards and
services that will best serve the heliophysics and space weather
science needs. As a natural follow up, IHDEA representatives are
actively participating to the information architecture and data analysis
overarching groups/clusters of the International Space Weather Action
Teams (ISWAT). Four action teams have emerged within these clusters
including: use of metadata to facilitate data science, data preparation
to advance machine Learning, on Digital Object Identifiers (DOI) to
support space weather and develop the use of Kamodo to enhance the
visualization in Python of the output of models. Thanks to the first
ISWAT conference held in February, each of these teams has defined a
list of actions. This presentation will be the opportunity to present
IHDEA, review the list of actions from these teams and invite the
heliophysics community at large to get involved in this endeavor.
Title: WHPI: A New Initiative on Solar Minimum
Authors: De Toma, Giuliana; Gibson, Sarah; Qian, Liying; Thompson,
Barbara
Bibcode: 2021cosp...43E.916D
Altcode:
The Whole Heliosphere and Planetary Interactions (WHPI) is an
international initiative focused around the solar minimum period
that aims to understand the interconnected Sun-heliospheric-planetary
system. The simpler magnetic configuration and infrequency of solar
eruptions makes solar minimum an ideal time to determine how the Sun's
radiative output, magnetic field and outflowing solar wind plasma
interact with the background heliosphere, the Earth and the other
planets. WHPI follows two similar initiatives during the previous solar
minima in 1996 and 2008-2009. The success of these efforts relies on a
broad participation of scientists worldwide and across disciplines. In
2019-2020 WHPI coordinated 3 different observing campaigns, each a
solar rotation long: The first was on Mar 12 - Apr 8, 2019 and targeted
two large, recurrent coronal holes and the associated high-speed solar
wind streams, the second one on Jun 29 - Jul 26 2019 was centered on
the total solar eclipse, and the third one on Jan 15 - Feb 11 2020
corresponded to the 4th Parker Solar Probe (PSP) encounter when the
Earth and many space observatories were near-radially aligned with
PSP. We describe the WHPI effort as an example of interdisciplinary
collaboration and report on the preliminary science results obtained
during the WHPI campaigns.
Title: SunCET: The Sun Coronal Ejection Tracker Concept
Authors: Mason, James Paul; Chamberlin, Phillip C.; Seaton, Daniel;
Burkepile, Joan; Colaninno, Robin; Dissauer, Karin; Eparvier, Francis
G.; Fan, Yuhong; Gibson, Sarah; Jones, Andrew R.; Kay, Christina; Kirk,
Michael; Kohnert, Richard; Pesnell, W. Dean; Thompson, Barbara J.;
Veronig, Astrid M.; West, Matthew J.; Windt, David; Woods, Thomas N.
Bibcode: 2021JSWSC..11...20M
Altcode: 2021arXiv210109215M
The Sun Coronal Ejection Tracker (SunCET) is an extreme ultraviolet
imager and spectrograph instrument concept for tracking coronal mass
ejections through the region where they experience the majority
of their acceleration: the difficult-to-observe middle corona. It
contains a wide field of view (0-4 R⊙) imager and a 1 Å
spectral-resolution-irradiance spectrograph spanning 170-340 Å. It
leverages new detector technology to read out different areas of the
detector with different integration times, resulting in what we call
"simultaneous high dynamic range", as opposed to the traditional high
dynamic range camera technique of subsequent full-frame images that
are then combined in post-processing. This allows us to image the
bright solar disk with short integration time, the middle corona
with a long integration time, and the spectra with their own,
independent integration time. Thus, SunCET does not require the use
of an opaque or filtered occulter. SunCET is also compact - ~15 × 15
× 10 cm in volume - making it an ideal instrument for a CubeSat or a
small, complementary addition to a larger mission. Indeed, SunCET is
presently in a NASA-funded, competitive Phase A as a CubeSat and has
also been proposed to NASA as an instrument onboard a 184 kg Mission
of Opportunity.
Title: Tracking CME substructure evolution through the solar wind
Authors: Gibson, S. E.; DeForest, C.; de Koning, C. A.; Fan, Y.;
Malanushenko, A. V.; Merkin, V. G.; Provornikova, E.; Thompson, B. J.;
Webb, D. F.
Bibcode: 2020AGUFMSH0280005G
Altcode:
Future coronagraphs and heliospheric imagers, in particular those
to be launched on the PUNCH mission, will have the capability to
track the evolution of CME substructures as the CME moves through and
interacts with the solar wind. We present analysis using polarization
data obtained from forward modeling simulations of CMEs in the corona
and inner heliosphere. We use these data to track the evolution
of substructures in three dimensions, and consider the diagnostic
potential of internal substructure vs structure at the front of the
CME. In particular, we develop methods for extracting information
about chirality of CME magnetic flux ropes from polarization data.
Title: Contemporary Analysis Methods for Coronagraph and Heliospheric
Imager Data
Authors: Thompson, B. J.; Attie, R.; Chhiber, R.; Cranmer, S. R.;
DeForest, C.; Gallardo-Lacourt, B.; Gibson, S. E.; Jones, S. I.;
Moraes Filho, V.; Reginald, N. L.; Uritsky, V. M.; Viall, N. M.
Bibcode: 2020AGUFMSH031..05T
Altcode:
Coronagraphs, polarimeters, and heliospheric imagers are providing
new insight into how structures in the solar wind form and develop as
they flow from the inner corona into the heliosphere. With this comes
a whole new frontier of physical observables in 3D, including kinetic
(velocity and acceleration), thermodynamic (density, temperature, and
shock boundary), and magnetic field properties. These measurements
inform and challenge models of global solar wind flow, turbulence,
and CME propagation. We will discuss recent advances in quantifying
physical properties of the corona and solar wind using coronagraph
and heliospheric imager data, and make predictions of what new models
and instrumentation (including the in-development PUNCH mission)
will bring us in the future.
Title: Snapshots of Solar Minimum: Data and Model Results From the
Past Two Solar Minima
Authors: Thompson, B. J.; Gibson, S. E.
Bibcode: 2020AGUFMSH0180002T
Altcode:
We present an overview of the data and models collected for the
Whole Sun Month (WSM; 1996) Whole Heliosphere Interval (WHI;
2008), two international campaigns to study the three-dimensional
solar-heliospheric-planetary connected system near solar minimum. The
data and models from WSM, which occurred during the solar minimum
between Cycles 22 and 23, provided new insight into how solar magnetic
structure forms the corona and inner heliosphere. WSM inspired the
Whole Heliosphere Interval campaign during the next solar minimum, and
the scientific goals expanded to study how solar minimum structures
affect processes in geospace. The data from WHI extended from below
the solar photosphere, through interplanetary space, and down to
Earth's mesosphere. Nearly 200 people participated in aspects of WHI
studies, analyzing and interpreting data from nearly 100 instruments and
models in order to elucidate the physics of fundamental heliophysical
processes. WSM and WHI studies traced the solar activity and structure
into the heliosphere and geospace, and provided new insight into
the nature of the interconnected heliophysical system near solar
minimum. This presentation gives insight into the motivation for the
Whole Heliosphere and Planetary Interactions campaigns.
Title: SunCET: A CubeSat Mission Dedicated to the Middle Corona
Authors: Mason, J. P.; Seaton, D. B.; Chamberlin, P. C.; Burkepile,
J.; Colaninno, R. C.; Dissauer, K.; Eparvier, F. G.; Fan, Y.; Gibson,
S. E.; Jones, A. R.; Kay, C.; Kirk, M. S.; Kohnert, R.; Thompson,
B. J.; Veronig, A.; West, M. J.; Woods, T. N.
Bibcode: 2020AGUFMSH0300006M
Altcode:
No abstract at ADS
Title: Velocity Flow Fields Derived from Coronagraph Data
Authors: Moraes Filho, V.; DeForest, C.; Thompson, B. J.; Uritsky,
V. M.
Bibcode: 2020AGUFMSH0280004M
Altcode:
In anticipation of the PUNCH mission, we examine deep exposure data
from the special campaign of the STEREO SECCHI COR2 instrument. Data
collected over April 14-16, 2014, representing altitudes of 4-15 solar
radii, show clear flow structures throughout the field of view. We
examine the variations in the derived flow as a function of altitude
and polar angle, to present a picture of the solar wind velocities
and acceleration through the corona and inner heliosphere.
Title: Understanding Solar Energetic Particle Events and CME Dynamics
in the Low Corona using MLSO and Spacebased Coronagraph Observations -
Progress Report
Authors: St Cyr, O. C.; Richardson, I. G.; Thompson, B. J.; Burkepile,
J.; Balmaceda, L.; Fry, D. J.
Bibcode: 2020AGUFMSH0090006S
Altcode:
We report here on the initial accelerations of coronal mass ejections
(CMEs) associated with 25 MeV solar energetic proton events (SEPs)
during the period 1980-1996. Primary CME observations in the low
corona were obtained at Mauna Loa Solar Observatory (MLSO) and,
where possible, they were combined with spacebased observations from
the SMM C/P and P78-1 Solwind coronagraphs. We identified 21 SEPs
with associated MLSO observations, and we were able to combine 12
of those with the spacebased coronagraphs to reveal the initial and
mid-coronal acceleration of the SEP-associated CMEs. We compared them
with 13 fast CMEs detected by MLSO during the same period with no
SEPs. The low-to-middle coronal accelerations of the SEP-associated
CMEs was significantly larger than for those without SEPs. We will
show examples of these statistics, and we will describe our progress
extending this work into the SOHO-LASCO era (1996-present).
Title: HSO Connect: Creating User-driven Infrastructure for Space
Science
Authors: Kirk, M. S.; Fung, S. F.; Ireland, J.; Jian, L.; Kuznetsova,
M. M.; MacNeice, P. J.; DiBraccio, G. A.; McGranaghan, R. M.; Roberts,
D. A.; Thomas, B. A.; Thompson, B. J.; Weigand, C.; Zheng, Y.
Bibcode: 2020AGUFMSH0180008K
Altcode:
The NASA Heliophysics System Observatory (HSO Connect) project is an
initiative to gain the most utility from data available for space
physics. The HSO Connect community comprises GSFC/NASA, NCAR's
Whole Heliosphere and Planetary Interactions (WHPI) program and
the Parker Solar Probe (PSP) project team at APL (Applied Physics
Lab). The purpose of HSO Connect is to unify the community and
provide observations coordinated around the PSP mission and other high
profile Heliophysics projects requiring unique integration. We share
the HSO Connect approach to curating and providing resources critical
to discovery, including observational data, related data products,
and basic tools to analyze the observations as well as providing the
same access to models and simulations which explain the data. To
support an interoperable and reusable data system to last beyond the
HSO Connect lifetime, we have worked with the community of end users to
identify, from their perspective, the most impactful "questions" which
they want HSO Connect to answer for them (for example, "Where the data
associated with phenomenon "X" might be stored and accessible?"). We
have utilized this feedback to prioritize how to better combine existing
capabilities and to identify which infrastructure capabilities need
to be augmented or created. We will show how we have utilized the
community feedback to determine both impact and ease of implementation,
used this information to derive critical requirements for HSO Connect
and used this information to align existing capabilities and create
missing infrastructure within resourcing limits.
Title: Filament Oscillations in Active Region 12076
Authors: Kucera, T. A.; Muglach, K.; Luna Bennasar, M.; Karpen, J.;
Thompson, B.; Gilbert, H.
Bibcode: 2020AAS...23633004K
Altcode:
We present an analysis of repeated large amplitude longitudinal
oscillations (LALO) in filaments in Active Region 12076 in May
and June of 2014. Most of the oscillations were associated with a
region of emerging and then canceling magnetic flux that resulted
in multiple activations and filament eruptions. We analyze twelve
separate oscillations that occur in a complex of filaments in the
active region over twelve days. Luna and Karpen (2012) model LALO
in filaments oscillations of magnetized filament plasma moving along
dipped magnetic field lines with gravity as a restoring force. Under
this model the period of these oscillations can be used to estimate
the curvature of the magnetic field in the location of the filament,
providing observationally derived values to compare with models of the
magnetic field in the active region corona. Periods ranged from 26-74
minutes, corresponding to magnetic field curvatures of about 20-130 Mm.
Title: VizieR Online Data Catalog: APOGEE-2 data from DR16 (Majewski+,
2017)
Authors: Majewski, S. R.; Schiavon, R. P.; Frinchaboy, P. M.;
Allende Prieto, C.; Barkhouser, R.; Bizyaev, D.; Blank, B.; Brunner,
S.; Burton, A.; Carrera, R.; Chojnowski, S. D.; Cunha, K.; Epstein,
C.; Fitzgerald, G.; Garcia Perez, A. E.; Hearty, F. R.; Henderson,
C.; Holtzman, J. A.; Johnson, J. A.; Lam, C. R.; Lawler, J. E.;
Maseman, P.; Meszaros, S.; Nelson, M.; Nguyen, D. C.; Nidever, D. L.;
Pinsonneault, M.; Shetrone, M.; Smee, S.; Smith, V. V.; Stolberg, T.;
Skrutskie, M. F.; Walker, E.; Wilson, J. C.; Zasowski, G.; Anders,
F.; Basu, S.; Beland, S.; Blanton, M. R.; Bovy, J.; Brownstein, J. R.;
Carlberg, J.; Chaplin, W.; Chiappini, C.; Eisenstein, D. J.; Elsworth,
Y.; Feuillet, D.; Fleming, S. W.; Galbraith-Frew, J.; Garcia, R. A.;
Garcia-Hernandez, D. A.; Gillespie, B. A.; Girardi, L.; Gunn, J. E.;
Hasselquist, S.; Hayden, M. R.; Hekker, S.; Ivans, I.; Kinemuchi,
K.; Klaene, M.; Mahadevan, S.; Mathur, S.; Mosser, B.; Muna, D.;
Munn, J. A.; Nichol, R. C.; O'Connell, R. W.; Parejko, J. K.; Robin,
A. C.; Rocha-Pinto, H.; Schultheis, M.; Serenelli, A. M.; Shane, N.;
Silva Aguirre, E. V.; Sob Eck, J. S.; Thompson, B.; Troup, N. W.;
Weinberg, D. H.; Zamora, O.
Bibcode: 2020yCat..51540094M
Altcode:
The second generation of the Apache Point Observatory Galactic Evolution
Experiment (APOGEE-2) observes the "archaeological" record embedded
in hundreds of thousands of stars to explore the assembly history and
evolution of the Milky Way Galaxy. APOGEE-2 maps the dynamical
and chemical patterns of Milky Way stars with data from the 1-meter
NMSU Telescope and the 2.5-meter Sloan Foundation Telescope at the
Apache Point Observatory in New Mexico (APOGEE-2N), and the 2.5-meter
du Pont Telescope at Las Campanas Observatory in Chile (APOGEE-2S). (2 data files).
Title: VizieR Online Data Catalog: APOGEE-2 data from DR16 (Majewski+,
2017)
Authors: Majewski, S. R.; Schiavon, R. P.; Frinchaboy, P. M.;
Allende Prieto, C.; Barkhouser, R.; Bizyaev, D.; Blank, B.; Brunner,
S.; Burton, A.; Carrera, R.; Chojnowski, S. D.; Cunha, K.; Epstein,
C.; Fitzgerald, G.; Garcia Perez, A. E.; Hearty, F. R.; Henderson,
C.; Holtzman, J. A.; Johnson, J. A.; Lam, C. R.; Lawler, J. E.;
Maseman, P.; Meszaros, S.; Nelson, M.; Nguyen, D. C.; Nidever, D. L.;
Pinsonneault, M.; Shetrone, M.; Smee, S.; Smith, V. V.; Stolberg, T.;
Skrutskie, M. F.; Walker, E.; Wilson, J. C.; Zasowski, G.; Anders,
F.; Basu, S.; Beland, S.; Blanton, M. R.; Bovy, J.; Brownstein, J. R.;
Carlberg, J.; Chaplin, W.; Chiappini, C.; Eisenstein, D. J.; Elsworth,
Y.; Feuillet, D.; Fleming, S. W.; Galbraith-Frew, J.; Garcia, R. A.;
Garcia-Hernandez, D. A.; Gillespie, B. A.; Girardi, L.; Gunn, J. E.;
Hasselquist, S.; Hayden, M. R.; Hekker, S.; Ivans, I.; Kinemuchi,
K.; Klaene, M.; Mahadevan, S.; Mathur, S.; Mosser, B.; Muna, D.;
Munn, J. A.; Nichol, R. C.; O'Connell, R. W.; Parejko, J. K.; Robin,
A. C.; Rocha-Pinto, H.; Schultheis, M.; Serenelli, A. M.; Shane, N.;
Silva Aguirre, E. V.; Sob Eck, J. S.; Thompson, B.; Troup, N. W.;
Weinberg, D. H.; Zamora, O.
Bibcode: 2020yCat.3284....0M
Altcode:
The second generation of the Apache Point Observatory Galactic Evolution
Experiment (APOGEE-2) observes the "archaeological" record embedded
in hundreds of thousands of stars to explore the assembly history and
evolution of the Milky Way Galaxy. APOGEE-2 maps the dynamical
and chemical patterns of Milky Way stars with data from the 1-meter
NMSU Telescope and the 2.5-meter Sloan Foundation Telescope at the
Apache Point Observatory in New Mexico (APOGEE-2N), and the 2.5-meter
du Pont Telescope at Las Campanas Observatory in Chile (APOGEE-2S). (2 data files).
Title: Fast and Wide CMEs without Observed >20 MeV Protons
Authors: Lario, D.; Kwon, R. Y.; Balmaceda, L.; Richardson, I. G.;
Krupar, V.; Thompson, B. J.; Cyr, O. C. St; Zhao, L.; Zhang, M.
Bibcode: 2020ApJ...889...92L
Altcode:
Statistical studies have found a close association between large solar
energetic particle (SEP) events and fast and wide coronal mass ejections
(CMEs). However, not all fast and wide CMEs have an associated SEP
event. From the Coordinated Data Analysis Web catalog of CMEs observed
by the Solar and Heliospheric Observatory (SOHO) between 2009 January
1 and 2014 September 30, we select fast (plane-of-sky speed >1000
km s-1) and wide (plane-of-sky angular width >120°)
CMEs and determine whether >20 MeV protons were detected by either
SOHO or the Solar TErrestrial RElations Observatory (STEREO-A or
STEREO-B). Among the 123 selected CMEs, only 11 did not produce a >20
MeV proton intensity increase at any of the three spacecraft. We use
multispacecraft coronagraph observations to reevaluate the speeds
and widths of the CMEs. The 11 CMEs without observed >20 MeV
protons tend to be in the narrow and slow end of the distribution
of the selected CMEs. We consider several factors that might play a
role in the nonobservation of high-energy particles in these events,
including (1) the ambiguous determination of the CME parameters,
(2) the inefficiency of the particle sources to produce >20 MeV
protons, (3) the lack of magnetic connection between particle sources
and any spacecraft, and (4) the lack of particles accelerated and
released during the parent solar eruptions. Whereas the extent of
the high Mach number regions formed in front of the CME is limited,
the characteristic that seems to distinguish those fast and wide CMEs
that lack observed >20 MeV protons is a deficit in the release of
particles during the solar eruptions.
Title: A New Expansive Catalog of Irradiance Coronal Dimming
Authors: Mason, J.; Attie, R.; Arge, C.; Thompson, B.; Woods, T.
Bibcode: 2020AAS...23535906M
Altcode:
When coronal mass ejections (CMEs) depart the corona, they leave behind
a transient void. Such a region evacuated of plasma is known as coronal
dimming and it contains information about the kinematics of the CME that
produced it. The dimming can be so great that it reduces the overall
energy output of the star in particular emission lines, i.e., dimming
is observable in spectral irradiance. This should be generally true for
magnetically active stars.We use the Solar Dynamics Observatory (SDO)
EUV Variability Experiment (EVE) data to search for and parameterize
dimming. We search these light curves for dimming around >8,500
≥C1 solar flares. In prior work, we have found that it is important
to remove the gradual flare phase from dimming light curves in order
to obtain slopes and magnitudes that are consistent with what can
be obtained by spatially isolating flaring loops in spectral image
data. Applying that method, we come to a total of ~13 million light
curves in which to search for dimming. We parameterize each light curve
in terms of magnitude, slope, and duration. Again in prior work, we've
found that irradiance dimming magnitude and slope are indicators of
CME mass and speed, respectively. Here, we briefly describe the feature
detection and characterization algorithms developed and applied to the
irradiance light curves. Machine learning techniques have been used for
some of the backend processing pipeline. We also present statistics on
the catalog itself. All of the code is open source python available
on GitHub (github.com/jmason86/James-s-EVE-Dimming-Index-JEDI). This
method may be capable of not only detecting CMEs from other stars,
but estimating their kinetic energy and frequency of occurrence;
information needed for assessing exoplanet habitability.
Title: Why do fast and wide CMEs not always produce observable solar
energetic particles?
Authors: Lario, D.; Kwon, R. Y.; Balmaceda, L.; Richardson, I. G.;
Zhang, M.; Zhao, L.; Krupar, V.; Thompson, B. J.
Bibcode: 2019AGUFMSH21B..02L
Altcode:
Statistical studies have found a close association between large
solar energetic particle (SEP) events and fast and wide coronal
mass ejections (CMEs). However, not all fast and wide CMEs have an
associated SEP event. The lack of an intense solar flare during the
parent solar eruption (Marque et al., 2006) or the slow evolution
of the CME speed at the origin of the solar eruption (Gopalswamy et
al., 2017) have been pointed out as possible factors that play a role
in the absence of high-energy particles. The observation by a given
spacecraft of the putative SEPs accelerated during these fast CMEs may
also depend on whether the spacecraft establishes magnetic connection
with the source of the SEPs and/or on how these SEPs propagate through
the interplanetary medium. From the list of CMEs in the CDAW LASCO
catalog during January 2009 - September 2014, we have selected fast
(plane-of-sky speeds >1000 km/s) and wide (angular width >120
deg) CMEs and determined whether >25 MeV protons were detected by
STEREO-A, STEREO-B or SOHO. Among the 123 selected CMEs, only eleven
CMEs did not produce a >25 MeV proton intensity increase at any
of the three spacecraft. By characterizing the shocks driven by these
CMEs, the magnetic connection established between the traveling shock
and each one of the three spacecraft, and the radio emission observed
during these events, we analyze the factors responsible for the absence
of observed >25 MeV proton increases in these events.
Title: Tracking supergranulation near the poles with SDO/HMI
Authors: Attié, R.; Kirk, M. S.; Tremblay, B.; Muglach, K.; Hess
Webber, S. A.; Pesnell, W. D.; Thompson, B. J.
Bibcode: 2019AGUFMSH13B..01A
Altcode:
Due to the spherical curvature of the Sun, solar observers suffer
from an increasing loss of resolution as we move away from the solar
equator. Thus knowledge of the photospheric flows near the poles
has eluded the scope of traditional flow tracking algorithms that
are using granules as tracers of the underlying flows. Using the new
"Balltracking" framework which we adapted to the observations from
SDO/HMI, we present an unprecedented analysis of the horizontal flow
fields at latitudes beyond +/- 60 degrees. The flow fields are derived
every 4 hours at a spatial resolution of 4 Mm. Using flow segmentation
techniques, we extract geometric and spectral information on the
supergranular cells and compare them with those of the supergranulation
at lower latitude. The correlation with the dynamics of moving magnetic
features is also investigated.
Title: Antidisciplinary: Tackling the technical and social challenges
to data science-driven discovery
Authors: McGranaghan, R. M.; Crichton, D. J.; Thompson, B. J.;
Guhathakurta, M.; Camporeale, E.; Doyle, R. J.
Bibcode: 2019AGUFMSA11C3227M
Altcode:
Data science refers to the set of tools, technologies, and teams that
alter the paradigm by which data are collected, managed and analyzed
. Data science is, therefore, decidedly broader than 'machine learning,'
and includes instead the full data lifecycle . Never has the need for
effective data science innovation been greater than now when at every
turn data-driven discovery is both burdened and invigorated by the
growth of data volumes, varieties, veracities, and velocities. This
growing scale of science requires dramatic shifts in collaborative
research, requiring projects to climb the gradations of collaboration
from unidisciplinary, to multi-, inter-, and transdisciplinary (Figure
1, [Hall et al., 2014; NRC, 2015]), and perhaps even to an entirely new
level that defies any traditional boundary, or anti disciplinary ( https://joi.ito.com/weblog/2014/10/02/antidisciplinar.html).
We will discuss the cutting-edge efforts advancing collaborative
research in Space Physics and Aeronomy, highlight progress, and
synthesize the lessons to provide a vision for future innovation
in data science for Heliophysics. We will specifically focus on
three trail-blazing initiatives: 1) the NASA Frontier Development
Laboratory; 2) the HelioAnalytics group at the Goddard Space Flight
Center in cooperation with the NASA Jet Propulsion Laboratory's Data
Science Working Group; and 3) an International Space Sciences Institute
project. References: Hall, K.L., Stipelman, B., Vogel, A.L., Huang,
G., and Dathe, M. (2014). Enhancing the Ef- fectiveness of Team-based
Research: A Dynamic Multi-level Systems Map of Integral Factors in
Team Science. Presented at the Fifth Annual Science of Team Science
Confer- ence, August, Austin, TX. NRC (National Research Council)
(2015). Enhancing the Effectiveness of Team Science. Washington, DC:
The National Academies Press. https://doi.org/10.17226/19007.
Title: Coronal Mass Ejections Observed by the Mauna Loa Solar
Observatory Coronagraphs and Their Association with Solar Energetic
Particle Events - A Progress Report
Authors: Richardson, I. G.; St Cyr, O. C.; Thompson, B. J.; Burkepile,
J.; Cane, H. V.
Bibcode: 2019AGUFMSH21B..05R
Altcode:
Studies using spacebased coronagraph measurements of the middle corona
indicate that coronal mass ejection (CME) dynamics provide information
about the characteristics of the resulting solar energetic particle
(SEP) event. For example, the peak SEP intensity at a given location in
space is dependent on the CME speed and direction and is also correlated
with the CME brightness. Furthermore, the SEP spectral hardness appears
to be related to the initial CME acceleration but this conclusion
is based on proxies for the acceleration below the field of view of
spacebased coronagraphs. Combining spacebased coronagraph observations
with groundbased observations of the low corona would eliminate the need
for such proxies and allow CME formation and the initial acceleration
to be observed directly. This paper is a report of progress on a study
of SEPs associated with CMEs detected since 1980 by coronameters at
the Mauna Loa Solar Observatory (MLSO) that can measure directly the
formation and initial accelerations of CMEs low in the corona (i.e.,
< 2 Rs) that occur during a nominal observing window of 17 - 02
UT. The MLSO observations of the initial CME signatures are combined
with observations from spacebased coronagraphs. We then compare the CME
characteristics with the properties of the related SEPs observed by
spacecraft near Earth and elsewhere in the heliosphere. The ultimate
goal is to assess whether there are certain characteristics of MLSO
CMEs that may indicate a likely association with SEP events, and if
so, whether a network of groundbased coronagraphs might be used for
SEP forecasting and for improving understanding of SEP acceleration
low in the corona.
Title: The PUNCH Bowl: Data System and Data Products for NASA's
PUNCH Mission
Authors: Thompson, B. J.; DeForest, C.; Gibson, S. E.
Bibcode: 2019AGUFMSA11C3231T
Altcode:
The Polarimeter to UNify the Corona and Heliosphere (PUNCH) mission
requires a flexible data system because the anticipated user base will
be using the data to tackle a wide range of science problems. Some will
be using PUNCH data in the classic "imager" context, while others will
be accessing the data to study solar wind dynamics. The PUNCH Bowl
provide PUNCH data, metadata, analysis tools, and higher-level PUNCH
data products, which are derived from heliospheric images to provide
additional information about structure and motion. Additionally, the
PUNCH Bowl is your access point for PUNCH Recipes: all of the tools,
code and routines that optimize the use of PUNCH data and streamline
your access. By running the "recipes" users can easily trace and
reproduce the steps used by others with minimal effort. The PUNCH Bowl
is maintained and supported by the PUNCH science team, but welcomes
contributions from users to ensure that everyone is able to easily
access all available tools and methods.
Title: AWARE: An Algorithm for the Automated Characterization of
EUV Waves in the Solar Atmosphere
Authors: Ireland, Jack; Inglis, Andrew R.; Shih, Albert Y.; Christe,
Steven; Mumford, Stuart; Hayes, Laura A.; Thompson, Barbara J.;
Hughitt, V. Keith
Bibcode: 2019SoPh..294..158I
Altcode: 2018arXiv180407325I
Extreme ultraviolet (EUV) waves are large-scale propagating
disturbances observed in the solar corona, frequently associated with
coronal mass ejections and flares. They appear as faint, extended
structures propagating from a source region across the structured
solar corona. Since their discovery, over 200 papers discussing their
properties, causes, and physical nature have been published. However,
despite this their fundamental properties and the physics of their
interactions with other solar phenomena are still not understood. To
further the understanding of EUV waves, we have constructed the
Automated Wave Analysis and Reduction (AWARE) algorithm for the
measurement of EUV waves. AWARE is implemented in two stages. In the
first stage, we use a new type of running difference image, the running
difference persistence image, which enables the efficient isolation of
propagating, bright wavefronts as they travel across the corona. In the
second stage, AWARE detects the presence of a wavefront, and measures
the distance, velocity, and acceleration of that wavefront across the
Sun. The fit of propagation models to the wave progress isolated in
the first stage is achieved using the Random Sample Consensus (RANSAC)
algorithm. AWARE is tested against simulations of EUV wave propagation,
and is applied to measure EUV waves in observational data from the
Atmospheric Imaging Assembly (AIA). We also comment on unavoidable
systematic errors that bias the estimation of wavefront velocity and
acceleration. In addition, the full AWARE software suite comes with a
package that creates simulations of waves propagating across the disk
from arbitrary starting points.
Title: The SDO/EVE Solar Irradiance Coronal Dimming Index
Catalog. I. Methods and Algorithms
Authors: Mason, James Paul; Attie, Raphael; Arge, Charles N.; Thompson,
Barbara; Woods, Thomas N.
Bibcode: 2019ApJS..244...13M
Altcode:
When a coronal mass ejection departs, it leaves behind a temporary
void. That void is known as coronal dimming, and it contains
information about the mass ejection that caused it. Other physical
processes can cause parts of the corona to have transient dimmings,
but mass ejections are particularly interesting because of their
influence in space weather. Prior work has established that dimmings
are detectable even in disk-integrated irradiance observations, i.e.,
Sun-as-a-star measurements. The present work evaluates four years of
continuous Solar Dynamics Observatory Extreme Ultraviolet Experiment
(EVE) observations to greatly expand the number of dimmings we may
detect and characterize, and collects that information into James’s
EVE Dimming Index catalog. This paper details the algorithms used
to produce the catalog, provides statistics on it, and compares it
with prior work. The catalog contains 5051 potential events (rows),
which correspond to all robustly detected solar eruptive events in this
time period as defined by >C1 flares. Each row has a corresponding
27,349 elements of metadata and parameterizations (columns). In total,
this catalog is the result of analyzing 7.6 million solar ultraviolet
light curves.
Title: Application usability levels: a framework for tracking project
product progress
Authors: Halford, Alexa J.; Kellerman, Adam C.; Garcia-Sage, Katherine;
Klenzing, Jeffrey; Carter, Brett A.; McGranaghan, Ryan M.; Guild,
Timothy; Cid, Consuelo; Henney, Carl J.; Ganushkina, Natalia Yu.;
Burrell, Angeline G.; Terkildsen, Mike; Welling, Daniel T.; Murray,
Sophie A.; Leka, K. D.; McCollough, James P.; Thompson, Barbara J.;
Pulkkinen, Antti; Fung, Shing F.; Bingham, Suzy; Bisi, Mario M.;
Liemohn, Michael W.; Walsh, Brian M.; Morley, Steven K.
Bibcode: 2019JSWSC...9A..34H
Altcode: 2019arXiv190708663H
The space physics community continues to grow and become both more
interdisciplinary and more intertwined with commercial and government
operations. This has created a need for a framework to easily identify
what projects can be used for specific applications and how close
the tool is to routine autonomous or on-demand implementation and
operation. We propose the Application Usability Level (AUL) framework
and publicizing AULs to help the community quantify the progress
of successful applications, metrics, and validation efforts. This
framework will also aid the scientific community by supplying the
type of information needed to build off of previously published work
and publicizing the applications and requirements needed by the user
communities. In this paper, we define the AUL framework, outline the
milestones required for progression to higher AULs, and provide example
projects utilizing the AUL framework. This work has been completed
as part of the activities of the Assessment of Understanding and
Quantifying Progress working group which is part of the International
Forum for Space Weather Capabilities Assessment.
Title: AWARE: An algorithm for the automated characterization of
EUV waves in the solar atmosphere
Authors: Ireland, Jack; Inglis, Andrew; Shih, Albert Y.; Christe,
Steven; Mumford, Stuart; Hayes, Laura A.; Thompson, Barbara J.;
Hughitt, V. Keith
Bibcode: 2019AAS...23410707I
Altcode:
Extreme ultraviolet (EUV) waves are large-scale propagating
disturbances observed in the solar corona, frequently associated with
coronal mass ejections and flares. They appear as faint, extended
structures propagating from a source region across the structured solar
corona. Since their discovery, over two hundred papers discussing their
properties, causes and physical nature have been published. However,
despite this their fundamental properties and the physics of their
interactions with other solar phenomena are still not understood. To
further the understanding of EUV waves, we have constructed the
Automated Wave Analysis and REduction (AWARE) algorithm for the
measurement of EUV waves. AWARE is implemented in two stages. In the
first stage, we use a new type of running difference image, the running
difference persistence image, which enables the efficient isolation
of propagating, brightening wavefronts as they propagate across the
corona. In the second stage, AWARE detects the presence of a wavefront,
and measures the distance, velocity and acceleration of that wavefront
across the Sun. The fit of propagation models to the wave progress
isolated in the first stage is achieved using the Random Sample and
Consensus (RANSAC) algorithm. AWARE is tested against simulations of EUV
wave propagation, and is applied to measure EUV waves in observational
data from the Atmospheric Imaging Assembly (AIA). We also comment on
unavoidable systematic errors that bias the estimation of wavefront
velocity and acceleration. In addition, the full AWARE software suite
comes with a package that creates simulations of waves propagating
across the disk from arbitrary starting points.
Title: Automatic Determination of Magnetosonic/Whistler Events in
the Solar Wind
Authors: Fordin, Samuel Karl; Shay, Michael; Wilson, Lynn, III;
Thompson, Barbara; Kirk, Michael
Bibcode: 2019shin.confE.165F
Altcode:
23 years of observations by the WIND spacecraft has yielded a
rich array of high-resolution magnetic field data, where a large
fraction displays small-scale structures. In particular, the solar
wind is full of magnetosonic-whistler-like fluctuations and kinetic
Alfven fluctuations that appear in both the field magnitude and its
components. Much of the previous work in the turbulence community
has focused on kinetic Alfven waves (KAWs) and the properties of
the associated spectral power law, with a break which occurs in the
0.1-5.0 Hz range. This frequency range corresponds to the spacecraft
frame frequency of magnetosonic-whistlers (MWs). Because solar wind
heating models depend on the sources of dissipation, the ability to
consistently distinguish between KAWs and MWs is vital to verifying
these models. Given the breadth of magnetic field data available,
machine learning is the most practical approach to classifying the
myriad small-scale structures observed in the magnetic field data. To
this end, a subset of current WIND data will be labeled and used as
a training set for a machine learning algorithm aimed at classifying
small-scale structures. This algorithm can then be used to catalog
the entire WIND magnetic field dataset.
Title: Coronal Mass Ejections Observed by the Mauna Loa Solar
Observatory Coronagraphs Associated with Solar Energetic Particle
Events - A Progress Report
Authors: Richardson, Ian G.; St. Cyr, O. C.; Thompson, B. J.;
Burkpile, J.
Bibcode: 2019shin.confE..26R
Altcode:
Studies using spacebased coronagraph measurements of the middle
corona indicate that CME dynamics provide information about the
characteristics of the resulting SEP event. For example, the peak
SEP intensity at a given location in space is dependent on the CME
speed and direction [e.g., Kahler, 2001; Richardson et al., 2014,
2018] and is also correlated with the CME brightness [Kahler &
Vourlidas, 2005]. Furthermore, the SEP spectral hardness appears to
be related to the initial CME acceleration [Gopalswamy et al., 2015,
2017], but this conclusion is based on proxies for the acceleration
below the field of view of spacebased coronagraphs. Combining spacebased
coronagraph observations with groundbased observations of the low corona
would eliminate the need for such proxies and allow CME formation
and the initial acceleration to be observed directly. This paper is
a progress report on a study of SEPs associated with CMEs detected
since 1980 by coronameters at the Mauna Loa Solar Observatory (MLSO)
that can measure directly the formation and initial accelerations
of CMEs low in the corona (i.e., < 2 Rs). The MLSO observations
of the initial CME signatures are combined with observations from
spacebased coronagraphs. We then compare the CME characteristics
with the properties of the related SEPs observed by spacecraft near
Earth and elsewhere in the heliosphere. In particular, we have now
identified all of the 1980-1996 MLSO CMEs with associated SEPs observed
for example by the IMP 8, ISEE-3 and Helios spacecraft, and summarize
their properties. We also note some of the challenges in associating
CMEs with SEPs and solar events in the pre-SOHO/WIND/ACE era.
Title: The Whole Heliosphere and Planetary Interactions (WHPI)
Initiative
Authors: Kolinski, Don; Gibson, Sarah; Thompson, Barbara; Bagenal,
Fran; de Toma, Giuliana; McGranaghan, Ryan; DiBraccio, Gina
Bibcode: 2019shin.confE.108K
Altcode:
The Whole Heliosphere and Planetary Interactions (WHPI) is a scientific
initiative with hundreds of participants worldwide to coordinate
observations and modeling of the solar-heliospheric-planetary system
during solar minimum and to promote and facilitate inter-disciplinary
activities. We do this by organizing observing campaigns and dedicated
science workshops to bring scientists from different scientific fields
together. The aim of WHPI is to better understand how the Sun’s output
affects the heliosphere and planets. The simpler magnetic configuration
of the Sun and the infrequency of CMEs make solar minimum an ideal
time to make such connection. Science objectives of WHPI include:
characterizing the 3D magnetic structure of the Sun and heliosphere
during the current minimum, following the propagation and evolution of
the Sun’s magnetic field through the solar wind and its interaction
with the magnetospheres of the Earth and other planets, quantifying
the effects of the solar radiative output the Earth and other planets,
and investigating the effect of a deep and prolonged solar minimum on
the entire heliosphere. With this poster, we invite the SHINE community
to join the WHPI initiative.
Title: VizieR Online Data Catalog: Precision cluster abund. for
APOGEE using SDSS DR14 (Donor+, 2018)
Authors: Donor, J.; Frinchaboy, P. M.; Cunha, K.; Thompson, B.;
O'Connell, J.; Zasowski, G.; Jackson, K. M.; McGrath, B. M.; Almeida,
A.; Bizyaev, D.; Carrera, R.; Garcia-Hernandez, D. A.; Nitschelm,
C.; Pan, K.; Zamora, O.
Bibcode: 2019yCat..51560142D
Altcode:
The primary spectroscopic data for OCCAM comes from the APOGEE
(Majewski et al. 2017AJ....154...94M), which is part of the
Sloan Digital Sky Survey-III and IV surveys (SDSS; Eisenstein et
al. 2011AJ....142...72E; Blanton et al. 2017AJ....154...28B), utilizing
the 2.5 m Sloan Foundation telescope (Gunn et al. 2006AJ....131.2332G)
at Apache Point Observatory. APOGEE is a near-infrared (1.514-1.696
μm) spectroscopic survey, primarily focusing on the Galactic disk
(Zasowski et al. 2013AJ....146...81Z, 2017AJ....154..198Z). The survey
uses multi-fiber spectrographs (Wilson et al. 2012SPIE.8446E..0HW),
allowing for simultaneous observations of 300 stars. The targets
selected for analysis were observed from 2011 August to 2014 July
(APOGEE-1), and from 2014 July to 2016 July (APOGEE-2). These data were
released as part of the 14th Data Release of SDSS (DR14; Abolfathi et
al. 2018ApJS..235...42A), which included APOGEE data for over 250000
stars. For this study, we analyzed all stars within 2x the cluster
radius (Kharchenko et al. 2013, J/A+A/558/A53) for 19 clusters that
resulted in a sample of 1361 stars. (5 data files).
Title: Irradiance Coronal Dimming and its Connection to CME Kinetics
Authors: Mason, James Paul; Arge, Nick; Krista, Larisza; Reinard,
Alysha; Thompson, Barbara J.; Webb, David F.; Wilson, Jake; Woods,
Thomas N.
Bibcode: 2018csc..confE..86M
Altcode:
When coronal mass ejections (CMEs) depart the corona, they leave
behind a transient void. Such a region evacuated of plasma is known
as a coronal dimming and it contains information about the kinetics
of the CME that produced it. The dimming can be so great in the
extreme ultraviolet (EUV) that it reduces the overall energy output
of the sun in particular emission lines, i.e., dimming is observable
in spectral irradiance. We use the Solar Dynamics Observatory (SDO)
EUV Variability Experiment (EVE) data to search for and parameterize
dimming. We focus our search on the 39 extracted emission lines data
product. We are searching these light curves for dimming around all
of the >8,500 ≥C1 solar flares in the SDO era. Our method of
combining these 39 light curves to remove the flare peak results in
1,521 light curves for every solar flare. Thus, we come to a total of
13 million light curves in which to search for dimming. The question
is: which ones are sensitive to CME-induced dimming? To answer this
and related questions, I'm using machine learning techniques built
into python's scikit-learn library. I will describe the results of
applying these techniques to the EVE data to produce the catalog,
to the catalog itself, and to comparisons with other related
catalogs. All of the code is open source python available on GitHub
(https://github.com/jmason86/James-s-EVE-Dimming-Index-JEDI).
Title: Dynamic Mapping of Solar Eruptions
Authors: Thompson, Barbara J.; DeVore, C. Richard; Hovis-Afflerbach,
Beryl A. C.; Uritsky, Vadim
Bibcode: 2018csc..confE..11T
Altcode:
We present the results of a prominence mapping effort designed to
extract the dynamics of erupting prominences and CMEs. The material from
partially erupting prominences can fall back to the sun, tracing out the
topology of the mid- and post-eruptive corona. One question involving
the range of observed behavior is the role of magnetic field topology
and evolution in determining the motion of the erupting prominence
material. A variable-g ballistic approximation is applied to study
the motion of the material, using the deviations from constant angular
momentum as a means of quantifying the local Lorentz (and other) forces
on each piece of material. Variations in dynamic behavior can be traced
back to changes in the local magnetic field. We discuss the use of the
prominence trajectories as a means of diagnosing eruptive topologies.
Title: Precursors of magnetic flux emergence in the moat flows of
active region AR12673
Authors: Attie, Raphael; Kirk, Michael; Thompson, Barbara; Muglach,
Karin; Norton, Aimee
Bibcode: 2018csc..confE..34A
Altcode:
We report on observations of magnetic disturbances in active region
AR12673 between Sep. 1 and Sep. 3, 2017 seen as a disruption of the moat
flow several hours before the onset of strong flux emergence near the
main sunspot. The moat flow is commonly known as a radially oriented
strong outflow of photospheric plasma surrounding sunspots which ends
abruptly and thus shapes an annular pattern around the penumbra. Using
highly accurate methods of tracking this photospheric flow applied
to SDO/HMI data, we are able to describe the evolution of the moat
surrounding the main sunspot of AR 12673. We find that several hours
before the emergence of strong magnetic flux near the main sunspot the
moat boundaries are broken at these very same locations. This behavior
is observed both on Sep. 1st and Sep. 3rd. There is no such behavior
observed in the absence of flux emergence. These observational results
pose the question of how often they occur in other active regions and
whether the disruption of the moat flow might be, like in this case,
an indication of impending enhanced magnetic activity or simply a
coincidental event.
Title: Driving Scientific Discovery with Machine Learning and AI at
the NASA GSFC Center for HelioAnalytics
Authors: Thompson, Barbara J.; Kirk, Michael S.; Sarantos, Menelaos
Bibcode: 2018csc..confE..81T
Altcode:
What is HelioAnalytics? This is a broad term meant to cover all the
ways that we harness advanced statistics, informatics and computer
science methods to achieve our science. Our focus is on problems that
we can attack with modern methods that we cannot attack otherwise. A
keener understanding of how information is derived from data, and how
machine learning can be harnessed to accomplish this, will expand
the discovery potential for key heliophysics research topics and
missions. We report on a new program to integrate modern information
science, statistics, and scientific knowledge to advance the fundamental
physics of connected sun-heliosphere-geospace system. The Center for
HelioAnalytics is an "expert group" at NASA GSFC focusing on topics
such as machine learning, neural networks, and data analytics in order
to expand the discovery potential for key heliophysics research topics
and missions. We define "HelioAnalytics" as a hybrid of Heliophysics
+ Machine Learning + Statistics + Information Design. Each of these
are fields that are well developed in their own right; HelioAnalytics
is the cross-disciplinary convergence of communities of physicists,
statisticians, and computer scientists. HelioAnalytics is intended to
foster research into advanced methodologies for heliophysical research,
and to promulgate such methods into the broader community.
Title: Extracting Solar Physics from 151 Million EUV Images
Authors: Kirk, Michael S.; Thompson, Barbara; Attie, Raphael;
Viall-Kepko, Nicki; Young, Peter
Bibcode: 2018csc..confE..88K
Altcode:
Beginning in 2010, the Solar Dynamics Observatory's Atmospheric Imaging
Assembly (SDO AIA) revolutionized solar imaging with its high temporal
and spatial resolution and coverage. The archive of extreme ultraviolet
(EUV) images is now over 150 million and continues to grow. Automated
algorithms consistently clean these images to remove magnetospheric
particle impacts on the CCD cameras, but it has been found that compact,
intense solar brightenings are often removed as well. There are now over
3 trillion "spiked pixels" that have been removed from EUV images. We
estimate that 0.001% of those are of solar origin and removed by mistake
- an unexplored dataset of about 30 million events. We take a novel
approach and survey the entire set of AIA "spike" data to identify and
group compact brightenings across the entire SDO mission. We then use
the spike database to form statistics on compact solar brightenings
without having to process large volumes of full-disk AIA data. The
qualities of the "spikes" with a solar origin represent the most
complete archive of compact EUV bright points ever assembled.
Title: AWARE: An algorithm for the automated characterization of
EUV waves in the solar atmosphere
Authors: Ireland, Jack; Inglis, Andrew; Shih, Albert; Christe, Steven;
Mumford, Stuart; Hayes, Laura; Thompson, Barbara; Hughitt, Keith
Bibcode: 2018csc..confE..21I
Altcode:
Extreme ultraviolet (EUV) waves are large-scale propagating
disturbances observed in the solar corona, frequently associated with
coronal mass ejections and flares. They appear as faint, extended
structures propagating from a source region across the structured solar
corona. Since their discovery, over two hundred papers discussing their
properties, causes and physical nature have been published. However,
despite this their fundamental properties and the physics of their
interactions with other solar phenomena are still not understood. To
further the understanding of EUV waves, we have constructed the
Automated Wave Analysis and REduction (AWARE) algorithm for the
measurement of EUV waves. AWARE is implemented in two stages. In the
first stage, we use a new type of running difference image, the running
difference persistence image, which enables the efficient isolation
of propagating, brightening wavefronts as they propagate across the
corona. In the second stage, AWARE detects the presence of a wavefront,
and measures the distance, velocity and acceleration of that wavefront
across the Sun. The fit of propagation models to the wave progress
isolated in the first stage is achieved using the Random Sample and
Consensus (RANSAC) algorithm. AWARE is tested against simulations of EUV
wave propagation, and is applied to measure EUV waves in observational
data from the Atmospheric Imaging Assembly (AIA). We also comment on
unavoidable systematic errors that bias the estimation of wavefront
velocity and acceleration. In addition, the full AWARE software suite
comes with a package that creates simulations of waves propagating
across the disk from arbitrary starting points.
Title: Tracing the Origins of the Solar Wind by Tracking Flows and
Disturbances in Coronagraph Data
Authors: Thompson, Barbara J.; Attie, Raphael; DeForest, Craig E.;
Gibson, Sarah E.; Hess Webber, Shea A.; Ireland, Jack; Kirk, Michael
S. F.; Kwon, Ryun Young; McGranaghan, Ryan; Viall, Nicholeen M.
Bibcode: 2018shin.confE..47T
Altcode:
The challenge of identifying transient motions in solar imagery has
been addressed in a number of ways. A variety of methods have been
developed to detect and characterize the motion and extent of coronal
mass ejections, for example. We discuss the adaptation of CME and
solar transient detection methods to trace smaller-scale perturbations
consistent with solar wind motions in the inner heliosphere (out to 10
RSun). We evaluate several methods, and compare the speed and structure
results to model predictions. In particular, we discuss how high-cadence
heliospheric imagery can be used to track small scale solar density
variations throughout the solar wind, serving as a proxy for in situ
velocity detection, but with global and continuous coverage.
Title: A Framework for Tracking Progress Towards Usability:
Application Usability Levels.
Authors: Halford, Alexa; Thompson, Barbara; Kellerman, Adam; Pulkkinen,
Antti; Garcia-Sage, Katherine
Bibcode: 2018cosp...42E1353H
Altcode:
As our community continues to grow and become more intertwined with
industry and other fields, there is a need for a framework that can
allow researchers and end users to identify applications for the
research, quantify metrics for each specific application, and enable
communication between the researchers and end users. To this end, the
Assessment of Understanding and Quantifying Progress International
Forum for Space Weather Capabilities Assessment working group has
developed the Application Usability Level (AUL) framework. The
AUL framework was developed by implementing lessons learned from
Technology Readiness Levels (TRLs) used by the instrument community
and Application Readiness Levels (ARLs) used by the Applied Science
program in NASA's Earth Science Division, as well as modifying the
levels and their milestones to better suit the needs of the Space
Weather and Heliophysics communities. In this talk we will introduce
the AUL framework and show examples of how it can be applied to
research for the Space Weather and Heliophysics communities. For more
information on the AULs and other work being done by the Assessment of
Understanding and Quantifying Progress International Forum for Space
Weather Capabilities Assessment working group, please see our website at
the CCMC https://ccmc.gsfc.nasa.gov/assessment/topics/trackprogress.php
Title: Prediction of Solar Energetic Particle Peak Intensity using
CME Speed and Direction in Solar Cycles 24 and 23
Authors: Richardson, Ian; Mays, Leila M.; Thompson, Barbara J.
Bibcode: 2018shin.confE.104R
Altcode:
We assess whether a formula obtained by Richardson et al. (2014)
(Solar Phys., 289, 3059, DOI 10.1007/s11207-014-0524-8) relating the
peak intensity of 14-24 MeV protons in a solar energetic particle event
at 1 AU to the solar event location and the speed of the associated
coronal mass ejection (CME), may be used to “predict" the intensity of
a solar energetic particle event. Starting with a set of all 334 CMEs in
the CCMC/SWRC DONKI real-time database during October, 2011-July 2012,
selected without consideration of whether they were associated with
SEP events, we use the CME speed and direction to predict the proton
intensity at Earth or the STEREO spacecraft using this formula. Since
most ( 85%) of these CMEs were not associated with SEP events, many
“false alarms" result. We demonstrate that considering the type
II or type III radio emissions that may accompany the CMEs can help
to improve the forecast skill, which we assess using several skill
scores. The method is also applied to over 1100 CMEs in solar cycle 23.
Title: 13 Million Light Curves, 122 Million Parameters, and the
Connection to Coronal Mass Ejections
Authors: Mason, James; Thompson, Barbara; Woods, Thomas; Webb, David;
Arge, Charles
Bibcode: 2018cosp...42E2194M
Altcode:
When coronal mass ejections (CMEs) depart the corona, they leave
behind a transient void. Such a region evacuated of plasma is known as
a coronal dimming and it contains information about the kinetics of
the CME that produced it. The dimming can be so great in the extreme
ultraviolet (EUV) that it reduces the overall energy output of the
sun in particular emission lines, i.e., dimming is observable in
spectral irradiance. This should be generally true for magnetically
active stars. The Solar Dynamics Observatory (SDO) EUV Variability
Experiment (EVE) data provide an excellent opportunity to search for and
parameterize dimming. We focus our search on the 39 extracted emission
lines data product. We search these light curves for dimming around
all of the >8,500 ≥C1 solar flares observed by the Geostationary
Operational Environmental Satellite (GOES) X-ray Sensor (XRS) in the
SDO era. In prior work, we have found that it is important to remove
the gradual flare phase from dimming light curves in order to obtain
slopes and magnitudes that are consistent with what can be obtained by
spatially isolating flaring loops in spectral image data. To do this,
we peak-match and subtract two different emission line light curves. In
this exhaustive search and characterization of dimming, we therefore
consider every permutation of the 39 emission lines as well as the
"uncorrected" light curves, resulting in 1,521 light curves for every
≥C1 solar flare. Thus, we come to a total of 13 million light curves
in which to search for dimming. We parameterize each light curve in
terms of magnitude, slope, and duration and correlate these with CME
speed and mass. Thus, we obtain a robust relationship between irradiance
coronal dimming and CME kinetics.Here, we briefly describe the feature
detection and characterization algorithms developed and applied to the
13 million EUV irradiance light curves. Machine learning techniques
have been used for both this backend processing pipeline and to analyze
the results. All of the code is open source python available on GitHub
(https://github.com/jmason86/James-s-EVE-Dimming-Index-JEDI). We then
provide preliminary results on the comparison between our new catalog
and the established Coordinated Data Analysis Workshops' CME Catalog.
Title: Advance detection of strong photospheric flux emergence
revealed by disruption of moat flows
Authors: Attié, Raphael; Thompson, Barbara J.; Muglach, Karin;
Norton, Aimee Ann
Bibcode: 2018tess.conf30602A
Altcode:
We report on observations of precursors of magnetic disturbances in AR
12673 seen as a disruption of the moat flow several hours before the
onset of strong flux emergence near the main sunspot. The moat flow is
commonly known as a radially oriented strong outflow of photospheric
plasma surrounding sunspots which ends abruptly and thus shapes an
annular pattern around the penumbra. Using highly accurate methods of
tracking this photospheric flow applied to SDO/HMI data, we are able
to describe the evolution of the moat surrounding the main sunspot of
AR 12673. We find that several hours before the emergence of strong
magnetic flux near the main sunspot the moat boundaries are broken at
these very same locations. Because we detect this specific behavior both
on Sep. 1st and Sep. 3rd, our observations suggest that the disruption
of the moat flow is a precursor of the enhanced magnetic activity
which, in this case, led to the strong flaring activity starting on
Sep 6th. This study is part of a broader statistical survey that
aims at characterizing emerging active regions. In light of these
new observations, our survey will also determine to what extent such
a disruption of the moat flow is followed by strong flux emergence
around sunspots, i.e., is this a peculiar response specific to AR
12673, or is it a characteristic disturbance defining a subset of
active regions prone to flaring activity?
Title: Tracking Flows and Disturbances in Coronagraph Data
Authors: Thompson, Barbara J.; Attie, Raphael; DeForest, Craig E.;
Gibson, Sarah E.; Hess Webber, Shea A.; Inglis, Anfew R.; Ireland,
Jack; Kirk, Michael S.; Kwon, RyunYoung; Viall, Nicholeen M.
Bibcode: 2018tess.conf30922T
Altcode:
The challenge of identifying transient motions in solar imagery has
been addressed in a number of ways. A variety of methods have been
developed to detect and characterize the motion and extent of coronal
mass ejections, for example. We discuss the adaptation of CME and
solar transient detection methods to trace smaller-scale perturbations
consistent with solar wind motions in the inner heliosphere (over 10
RSun). We evaluate several methods, and compare the speed and structure
results to model predictions. In particular, we discuss how high-cadence
heliospheric imagery can be used to track small scale solar density
variations throughout the solar wind, serving as a proxy for in situ
velocity detection, but with global and continuous coverage.
Title: Observations of \sim25 MeV Energetic Particle Events Made by
the High Energy Telescopes During the STEREO Mission
Authors: Richardson, Ian G.; von Rosenvinge, Tycho T.; Cane, Hilary
V.; Thompson, Barbara J.; Kwon, RyunYoung
Bibcode: 2018tess.conf21367R
Altcode:
We summarize some of the results from the High Energy Telescopes (HETs)
on the STEREO spacecraft which made observations of 0.7-4 MeV electrons
and 13.6-100 MeV protons since the beginning of the mission in late
2006, including the detection of over 300 solar energetic particle
events that included 25 MeV protons, of which around 40 were observed
at both STEREO spacecraft and at the Earth. We also show observations
during the most recent events in September-October, 2017, and consider
the lessons learned from the STEREO HET observations.
Title: Tracking algorithms and machine learning for the
characterization of active regions over the solar cycle 24
Authors: Attié, Raphael; Thompson, Barbara J.; Kirk, Mechael S.;
Norton, Aimee Ann
Bibcode: 2018tess.conf31604A
Altcode:
Since the year 2010, SDO is sending more than a terabyte of solar
observations per day. By offering such an unprecedented large
and varied data sets, this mission has propelled the solar physics
community into the era of "Big Data" analytics. As an answer to this
new technical and scientific challenge, we present here a threefold
innovative framework for efficient data mining and analysis of the solar
photosphere using SDO/HMI: (i) A method for tracking the horizontal
photospheric flows uses an improved version of "Balltracking". We will
present the most recent version of this feature tracking algorithm,
its advantage over other more traditional methods like Local
Correlation Tracking (LCT) and how it has been specifically tuned
to handle the massive HMI datastream. Coupled with flow segmentation
algorithms, it offers an unprecedented view of the evolution of the
supergranulation. (ii) A method for tracking the magnetic flux
using HMI data called "Magnetic Balltracking". We will show how it
enables us to accurately track magnetic elements on magnetograms in
the Lagrange reference frame, and systematically derive parameters
such as the position, velocity, and fragments area and how we use
it to automate the detection of flux emergence. (iii) The above
methods define a tracking framework whose output feed databases that
become the input of machine learning algorithms for classification
purposes. We will show how this expands our knowledge-base e.g. on
the properties of large-scale photospheric flows prior to and after
the emergence of active regions, and on how the flows interact with
the magnetic field over large areas and long time scales. Through
these examples we will demonstrate how this framework contributes to
a sensible characterization of the evolution of active regions during
the whole solar cycle.
Title: Correlating Flare Oscillations with Photospheric Wave Responses
Authors: Hess Webber, Shea A.; Thompson, Barbara J.; Zhao, Junwei
Bibcode: 2018tess.conf30493H
Altcode:
Applying the Time-Convolution Mapping Method (TCMM) to multiple SDO/AIA
wavelengths, we track plasma oscillations in the chromosphere and low
corona during several X-class flares. These results will be used to
determine travel times for the oscillations along the flare loops. The
ultimate goal is to correlate these travel times with photospheric wave
responses. Understanding how flare oscillations effect the photosphere
can detail the mechanics and solar environment around flaring active
regions.
Title: Prediction of Solar Energetic Particle Peak Intensity using
CME Speed and Direction in Solar Cycle 24 and Earlier Cycles
Authors: Richardson, Ian G.; Mays, M. Leila; Thompson, Barbara J.
Bibcode: 2018tess.conf21369R
Altcode:
From a survey of solar energetic particle events observed by both the
STEREO spacecraft and at the Earth in 2009-2012 during solar cycle 24,
Richardson et al. (Solar Physics, 289,3059, 2014) obtained a formula
relating the SEP peak intensity at 14-24 MeV with the speed of the
associated coronal mass ejection and its direction with respect to the
observing spacecraft. This suggests that the formula might in turn be
used, if the CME parameters are known, to "predict" the intensity of
the related SEP event. However, since only a small fraction of CMEs
are actually associated with SEPs at this energy, many "false alarms"
occur. These may be reduced by, for example, considering a minimum CME
width, or other phenomena, such as type II and type III radio emissions,
accompanying the CME. For a subset of cycle 24 CMEs, in around three
quarters of cases where the observed proton intensity at 14-24 MeV
was above 0.1 (cm<svg xmlns:xlink="http://www.w3.org/1999/xlink"
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since cycle 24 SEP events were used to generate the formula, it
is also possible that this contributes the good agreement between
observed and predicted SEP intensities. We have therefore applied it
to CMEs in solar cycle 23, using CME speeds from the CDAW catalog and
directions inferred from the location of the associated flare, and
find that there is a similar level of agreement. For earlier cycles,
we use CME observations from the Solwind and SMM coronagraphs associated
with SEP events. In addition, for SEP events in earlier cycles where
the SEP intensity and flare location are known, the speed of the
associated CME might be estimated using the formula, assuming that it
also holds for these earlier cycles, thereby indicating the speeds of
SEP-associated CMEs even if there are no coronagraph observations.
Title: Correlating Flare Oscillations with Photospheric Wave Responses
Authors: Hess Webber, Shea A.; Thompson, Barbara J.; Zhao, Junwei
Bibcode: 2018ress.meetE...1H
Altcode:
Applying the Time-Convolution Mapping Method (TCMM) to multiple SDO/AIA
wavelengths, we track plasma oscillations in the chromosphere and low
corona during several X-class flares. These results will be used to
determine travel times for the oscillations along the flare loops. The
ultimate goal is to correlate these travel times with photospheric wave
responses. Understanding how flare oscillations effect the photosphere
can detail the mechanics and solar environment around flaring active
regions.
Title: Space Weather Research and Forecasting Capabilities at the
Community Coordinated Modeling Center (CCMC)
Authors: Collado-Vega, Y. M.; Kuznetsova, M.; Mays, L.; Pulkkinen,
A.; Zheng, Y.; Muglach, K.; Thompson, B.; Chulaki, A.; Taktakishvili,
A.; CCMC Team
Bibcode: 2018LPICo2063.3090C
Altcode:
The Community Coordinated Modeling Center (CCMC) supports and enables
the research and development of the latest and future space weather
models and facilitates the deployment of the latest advances in research
of space weather operations.
Title: Physical Conditions in the Solar Corona Derived from the
Total Solar Eclipse Observations obtained on 2017 August 21 Using
a Polarization Camera
Authors: Gopalswamy, N.; Yashiro, Seiji; Reginald, Nelson; Thakur,
Neeharika; Thompson, Barbara J.; Gong, Qian
Bibcode: 2018AAS...23122008G
Altcode:
We present preliminary results obtained by observing the solar corona
during the 2017 August 21 total solar eclipse using a polarization
camera mounted on an eight-inch Schmidt-Cassegrain telescope. The
observations were made from Madras Oregon during 17:19 to 17:21
UT. Total and polarized brightness images were obtained at four
wavelengths (385, 398.5, 410, and 423 nm). The polarization camera had a
polarization mask mounted on a 2048x2048 pixel CCD with a pixel size of
7.4 microns. The resulting images had a size of 975x975 pixels because
four neighboring pixels were summed to yield the polarization and total
brightness images. The ratio of 410 and 385 nm images is a measure
of the coronal temperature, while that at 423 and 398.5 nm images
is a measure of the coronal flow speed. We compared the temperature
map from the eclipse observations with that obtained from the Solar
Dynamics Observatory’s Atmospheric Imaging Assembly images at six EUV
wavelengths, yielding consistent temperature information of the corona.
Title: Studying the Kinematic Behavior of Coronal Mass Ejections
and Other Solar Phenomena using the Time-Convolution Mapping Method
Authors: Hess Webber, Shea A.; Thompson, Barbara J.; Kwon, Ryun Young;
Ireland, Jack
Bibcode: 2018AAS...23131504H
Altcode:
An improved understanding of the kinematic properties of CMEs and
CME-associated phenomena has several impacts: 1) a less ambiguous
method of mapping propagating structures into their inner coronal
manifestations, 2) a clearer view of the relationship between the
“main” CME and CME-associated brightenings, and 3) an improved
identification of the heliospheric sources of shocks, Type II
bursts, and SEPs. We present the results of a mapping technique that
facilitates the separation of CMEs and CME-associated brightenings
(such as shocks) from background corona. The Time Convolution Mapping
Method (TCMM) segments coronagraph data to identify the time history
of coronal evolution, the advantage being that the spatiotemporal
evolution profiles allow users to separate features with different
propagation characteristics. For example, separating “main”
CME mass from CME-associated brightenings or shocks is a well-known
obstacle, which the TCMM aids in differentiating. A TCMM CME map is
made by first recording the maximum value each individual pixel in
the image reaches during the traversal of the CME. Then the maximum
value is convolved with an index to indicate the time that the pixel
reached that value. The TCMM user is then able to identify continuous
“kinematic profiles,” indicating related kinematic behavior, and
also identify breaks in the profiles that indicate a discontinuity in
kinematic history (i.e. different structures or different propagation
characteristics). The maps obtained from multiple spacecraft viewpoints
(i.e., STEREO and SOHO) can then be fit with advanced structural models
to obtain the 3D properties of the evolving phenomena. We will also
comment on the TCMM's further applicability toward the tracking of
prominences, coronal hole boundaries and coronal cavities.
Title: Tracking Photospheric Energy Transport in Active Regions
with SDO
Authors: Attié, R.; Thompson, B. J.
Bibcode: 2017AGUFMSH13A2470A
Altcode:
The solar photosphere presents flow fields at all observable
scales. Where energy-bearing magnetic active regions break through
the photosphere these flows are particularly strong, as sheared and
twisted magnetic fields come into equilibrium with their surroundings
while transporting magnetic energy into the corona. A part of this
magnetic energy - the so-called `free energy' stored in the magnetic
field in the form of "twisted" and shear of the field - is released in
flares and eruptions. We can quantify the energy arrival and build-up
in the corona by tracking flow fields and magnetic features at the
photosphere as magnetic flux emerges and evolves before and after
a flare or eruption.To do this reliably requires two things: a long
series of photospheric observations at high sensitivity, spatial and
temporal resolution, and an efficient, reliable and robust framework
that tracks the photospheric plasma flows and magnetic evolution in both
the quiet sun and active regions. SDO/HMI provides the observations, and
we present here an innovative high resolution tracking framework that
involves the `Balltracking' and `Magnetic Balltracking' algorithms. We
show the first results of a systematic, quantitative and comprehensive
measurements of the flows and transport of magnetic energy into the
solar atmosphere and investigate whether this dynamic view can improve
predictions of flares and Coronal Mass Ejections (CMEs).
Title: Prediction of SEP Peak Proton Intensity Based on CME Speed,
Direction and Observations of Associated Solar Phenomena
Authors: Richardson, I. G.; Mays, M. L.; Thompson, B. J.; Kwon, R.;
Frechette, B. P.
Bibcode: 2017AGUFMSH31B2735R
Altcode:
We assess whether a formula obtained by Richardson et al. (Solar
Phys., 289, 3059, 2014; DOI 10.1007/s11207-014-0524-8) relating the
intensity of 14-24 MeV protons in a solar energetic particle event
at 1 AU to the solar event location and the speed of the associated
coronal mass ejection (CME), may be used to "predict" the intensity
of a solar energetic particle event. Starting with a subset of
several hundred CMEs in the CCMC/SWRC DONKI real-time database
(http://kauai.ccmc.gsfc.nasa.gov/DONKI/) selected without consideration
of whether they were associated with SEP events, we first use the CME
speed and direction to predict the proton intensity at Earth or the
STEREO spacecraft using this formula. Since most of these CMEs were
not in fact associated with SEP events, many "false alarms" result. We
then examine whether considering other phenomena which may accompany
the CMEs, such as the X-ray flare intensity and the properties of type
II and type III radio emissions, may help to reduce the false alarm
rate. We also use CME parameters calculated from an ellipsoidal shell
fit to multi-spacecraft CME shock observations for a smaller number
of events to predict the SEP intensity. We calculate skill scores for
each case and assess whether the Richardson et al. (2014) formula,
using additional observations to reduce the false alarm rate, has
any potential as a SEP prediction tool, assuming that the required
observations could be acquired sufficiently rapidly following the
onset of the related solar event/CME.
Title: Deriving and Constraining 3D CME Kinematic Parameters from
Multi-Viewpoint Coronagraph Images
Authors: Thompson, B. J.; Mei, H. F.; Barnes, D.; Colaninno, R. C.;
Kwon, R.; Mays, M. L.; Mierla, M.; Moestl, C.; Richardson, I. G.;
Verbeke, C.
Bibcode: 2017AGUFMSH31A2714T
Altcode:
Determining the 3D properties of a coronal mass ejection using
multi-viewpoint coronagraph observations can be a tremendously
complicated process. There are many factors that inhibit the
ability to unambiguously identify the speed, direction and shape
of a CME. These factors include the need to separate the "true"
CME mass from shock-associated brightenings, distinguish between
non-radial or deflected trajectories, and identify asymmetric CME
structures. Additionally, different measurement methods can produce
different results, sometimes with great variations. Part of the reason
for the wide range of values that can be reported for a single CME
is due to the difficulty in determining the CME's longitude since
uncertainty in the angle of the CME relative to the observing image
planes results in errors in the speed and topology of the CME. Often
the errors quoted in an individual study are remarkably small when
compared to the range of values that are reported by different authors
for the same CME. For example, two authors may report speeds of 700
+- 50 km/sec and 500+-50 km/sec for the same CME. Clearly a better
understanding of the accuracy of CME measurements, and an improved
assessment of the limitations of the different methods, would be
of benefit. We report on a survey of CME measurements, wherein we
compare the values reported by different authors and catalogs. The
survey will allow us to establish typical errors for the parameters
that are commonly used as inputs for CME propagation models such
as ENLIL and EUHFORIA. One way modelers handle inaccuracies in CME
parameters is to use an ensemble of CMEs, sampled across ranges of
latitude, longitude, speed and width. The CMEs simulated in order to
determine the probability of a "direct hit" and, for the cases with a
"hit," derive a range of possible arrival times. Our study will provide
improved guidelines for generating CME ensembles that more accurately
sample across the range of plausible values.
Title: CCMC: bringing space weather awareness to the next generation
Authors: Chulaki, A.; Muglach, K.; Zheng, Y.; Mays, M. L.; Kuznetsova,
M. M.; Taktakishvili, A.; Collado-Vega, Y. M.; Rastaetter, L.; Mendoza,
A. M. M.; Thompson, B. J.; Pulkkinen, A. A.; Pembroke, A. D.
Bibcode: 2017AGUFMSH21A2635C
Altcode:
Making space weather an element of core education is critical for
the future of the young field of space weather. Community Coordinated
Modeling Center (CCMC) is an interagency partnership established to
aid the transition of modern space science models into space weather
forecasting while supporting space science research. Additionally, over
the past ten years it has established itself as a global space science
education resource supporting undergraduate and graduate education and
research, and spreading space weather awareness worldwide. A unique
combination of assets, capabilities and close ties to the scientific
and educational communities enable our small group to serve as a hub
for rising generations of young space scientists and engineers. CCMC
offers a variety of educational tools and resources publicly available
online and providing access to the largest collection of modern space
science models developed by the international research community. CCMC
has revolutionized the way these simulations are utilized in
classrooms settings, student projects, and scientific labs. Every
year, this online system serves hundreds of students, educators and
researchers worldwide. Another major CCMC asset is an expert space
weather prototyping team primarily serving NASA's interplanetary space
weather needs. Capitalizing on its unique capabilities and experiences,
the team also provides in-depth space weather training to hundreds of
students and professionals. One training module offers undergraduates an
opportunity to actively engage in real-time space weather monitoring,
analysis, forecasting, tools development and research, eventually
serving remotely as NASA space weather forecasters. In yet another
project, CCMC is collaborating with Hayden Planetarium and Linkoping
University on creating a visualization platform for planetariums (and
classrooms) to provide simulations of dynamic processes in the large
domain stretching from the solar corona to the Earth's upper atmosphere,
for near real-time and historical space weather events.
Title: Assessing and Adapting Scientific Results for Space Weather
Research to Operations (R2O)
Authors: Thompson, B. J.; Friedl, L.; Halford, A. J.; Mays, M. L.;
Pulkkinen, A. A.; Singer, H. J.; Stehr, J. W.
Bibcode: 2017AGUFMSM11E..04T
Altcode:
Why doesn't a solid scientific paper necessarily result in a tangible
improvement in space weather capability? A well-known challenge in
space weather forecasting is investing effort to turn the results of
basic scientific research into operational knowledge. This process
is commonly known as "Research to Operations," abbreviated R2O. There
are several aspects of this process: 1) How relevant is the scientific
result to a particular space weather process? 2) If fully utilized, how
much will that result improve the reliability of the forecast for the
associated process? 3) How much effort will this transition require? Is
it already in a relatively usable form, or will it require a great deal
of adaptation? 4) How much burden will be placed on forecasters? Is
it "plug-and-play" or will it require effort to operate? 5) How
can robust space weather forecasting identify challenges for new
research? This presentation will cover several approaches that have
potential utility in assessing scientific results for use in space
weather research. The demonstration of utility is the first step,
relating to the establishment of metrics to ensure that there will be
a clear benefit to the end user. The presentation will then move to
means of determining cost vs. benefit, (where cost involves the full
effort required to transition the science to forecasting, and benefit
concerns the improvement of forecast reliability), and conclude with a
discussion of the role of end users and forecasters in driving further
innovation via "O2R."
Title: The Far Ultra-Violet Imager on the Icon Mission
Authors: Mende, S. B.; Frey, H. U.; Rider, K.; Chou, C.; Harris,
S. E.; Siegmund, O. H. W.; England, S. L.; Wilkins, C.; Craig, W.;
Immel, T. J.; Turin, P.; Darling, N.; Loicq, J.; Blain, P.; Syrstad,
E.; Thompson, B.; Burt, R.; Champagne, J.; Sevilla, P.; Ellis, S.
Bibcode: 2017SSRv..212..655M
Altcode: 2017SSRv..tmp...77M
ICON Far UltraViolet (FUV) imager contributes to the ICON science
objectives by providing remote sensing measurements of the daytime and
nighttime atmosphere/ionosphere. During sunlit atmospheric conditions,
ICON FUV images the limb altitude profile in the shortwave (SW)
band at 135.6 nm and the longwave (LW) band at 157 nm perpendicular
to the satellite motion to retrieve the atmospheric O/N2
ratio. In conditions of atmospheric darkness, ICON FUV measures the
135.6 nm recombination emission of O+ ions used to compute
the nighttime ionospheric altitude distribution. ICON Far UltraViolet
(FUV) imager is a Czerny-Turner design Spectrographic Imager with
two exit slits and corresponding back imager cameras that produce two
independent images in separate wavelength bands on two detectors. All
observations will be processed as limb altitude profiles. In addition,
the ionospheric 135.6 nm data will be processed as longitude and
latitude spatial maps to obtain images of ion distributions around
regions of equatorial spread F. The ICON FUV optic axis is pointed 20
degrees below local horizontal and has a steering mirror that allows
the field of view to be steered up to 30 degrees forward and aft, to
keep the local magnetic meridian in the field of view. The detectors
are micro channel plate (MCP) intensified FUV tubes with the phosphor
fiber-optically coupled to Charge Coupled Devices (CCDs). The dual
stack MCP-s amplify the photoelectron signals to overcome the CCD
noise and the rapidly scanned frames are co-added to digitally create
12-second integrated images. Digital on-board signal processing is
used to compensate for geometric distortion and satellite motion and
to achieve data compression. The instrument was originally aligned in
visible light by using a special grating and visible cameras. Final
alignment, functional and environmental testing and calibration were
performed in a large vacuum chamber with a UV source. The test and
calibration program showed that ICON FUV meets its design requirements
and is ready to be launched on the ICON spacecraft.
Title: Improving Our Understanding of the 3D Coronal Evolution of
CME Propagation
Authors: Hess Webber, Shea A.; Thompson, Barbara J.; Ireland, Jack;
Kwon, Ryun Young
Bibcode: 2017SPD....4820603H
Altcode:
An improved understanding of the kinematic properties of CMEs and
CME-associated phenomena has several impacts: 1) a less ambiguous
method of mapping propagating structures into their inner coronal
manifestations, 2) a clearer view of the relationship between the
“main” CME and CME-associated brightenings, and 3) an improved
identification of the heliospheric sources of shocks, Type II
bursts, and SEPs. We present the results of a mapping technique that
facilitates the separation of CMEs and CME-associated brightenings
(such as shocks) from background corona. The Time Convolution Mapping
Method (TCMM) segments coronagraph data to identify the time history
of coronal evolution, the advantage being that the spatiotemporal
evolution profiles allow users to separate features with different
propagation characteristics. For example, separating “main”
CME mass from CME-associated brightenings or shocks is a well-known
obstacle, which the TCMM aids in differentiating. A TCMM CME map is
made by first recording the maximum value each individual pixel in
the image reaches during the traversal of the CME. Then the maximum
value is convolved with an index to indicate the time that the pixel
reached that value. The TCMM user is then able to identify continuous
“kinematic profiles,” indicating related kinematic behavior, and
also identify breaks in the profiles that indicate a discontinuity in
kinematic history (i.e. different structures or different propagation
characteristics). The maps obtained from multiple spacecraft viewpoints
(i.e., STEREO and SOHO) can then be fit with advanced structural models
to obtain the 3D properties of the evolving phenomena.
Title: Observations of Magnetic Evolution and Network Flares Driven
by Photospheric Flows in the Quiet Sun
Authors: Attie, Raphael; Thompson, Barbara J.
Bibcode: 2017SPD....4810105A
Altcode:
The quiet Sun may be the biggest laboratory to study physical elementary
processes of fundamental importance to space plasma. The advantage
is the continuous availability of small-scale events, carrying the
hidden microphysics that is responsible for larger-scale phenomena. By
small-scale events, we mean spatial dimensions of a few Mm at most,
and durations of less than an hour. I present here an attempt to
describe and understand the coupling between the photospheric flows,
the photospheric magnetic flux, and small-scale energetic transient
events. By adapting and improving the highly efficient Balltracking
technique for Hinode/SOT data, we relate the fine structures of the
supergranular flow fields with the magnetic flux evolution. For
studying the dynamics of the latter, and more precisely, the
magnetic flux cancellation at sites of energy releases, we applied
a new feature tracking algorithm called "Magnetic Balltracking" --
which tracks photospheric magnetic elements -- to high-resolution
magnetograms from Hinode/SOT.Using observations of the low corona
in soft X-rays with Hinode/XRT, we analyse the triggering mechanism
of small-scale network flares. By tracking both the flow fields on
the one hand, and the magnetic motions on the other hand, we relate
the flows with cancelling magnetic flux. We identify two patterns
of horizontal flows that act as catalysts for efficient magnetic
reconnection: (i) Funnel-shaped streamlines in which the magnetic
flux is carried, and (ii) large-scale vortices (~10 Mm and above)
at the network intersections, in which distant magnetic features of
opposite polarities seem to be sucked in and ultimately vanish. The
excess energy stored in the stressed magnetic field of the vortices
is sufficient to power network flares.Prospects for determining the
magnetic energy budget in the quiet sun are discussed.
Title: Network Flares and Magnetic Evolution Driven by Photospheric
Flows in the Quiet Sun
Authors: Attie, Raphael; Thompson, Barbara J.
Bibcode: 2017shin.confE..58A
Altcode:
The quiet Sun may be the biggest laboratory to study physical elementary
processes of fundamental importance to space plasma. The advantage
is the continuous availability of small-scale events, carrying the
hidden microphysics that is responsible for larger-scale phenomena. By
small-scale events, we mean spatial dimensions of a few Mm at most,
and durations of less than an hour. I present here an attempt to
describe and understand the coupling between the photospheric flows,
the photospheric magnetic flux, and small-scale energetic transient
events. By adapting and improving the highly efficient Balltracking
technique for Hinode/SOT data, we relate the fine structures of
the supergranular flow fields with the magnetic flux evolution. For
studying the magnetic flux cancellation at sites of energy releases,
we applied a new feature tracking algorithm called
Title: The Solar Energetic Particle Event of 2010 August 14:
Connectivity with the Solar Source Inferred from Multiple Spacecraft
Observations and Modeling
Authors: Lario, D.; Kwon, R. -Y.; Richardson, I. G.; Raouafi, N. E.;
Thompson, B. J.; von Rosenvinge, T. T.; Mays, M. L.; Mäkelä, P. A.;
Xie, H.; Bain, H. M.; Zhang, M.; Zhao, L.; Cane, H. V.; Papaioannou,
A.; Thakur, N.; Riley, P.
Bibcode: 2017ApJ...838...51L
Altcode:
We analyze one of the first solar energetic particle (SEP) events
of solar cycle 24 observed at widely separated spacecraft in order
to assess the reliability of models currently used to determine the
connectivity between the sources of SEPs at the Sun and spacecraft in
the inner heliosphere. This SEP event was observed on 2010 August 14 by
near-Earth spacecraft, STEREO-A (∼80° west of Earth) and STEREO-B
(∼72° east of Earth). In contrast to near-Earth spacecraft, the
footpoints of the nominal magnetic field lines connecting STEREO-A
and STEREO-B with the Sun were separated from the region where the
parent fast halo coronal mass ejection (CME) originated by ∼88° and
∼47° in longitude, respectively. We discuss the properties of the
phenomena associated with this solar eruption. Extreme ultraviolet and
white-light images are used to specify the extent of the associated
CME-driven coronal shock. We then assess whether the SEPs observed
at the three heliospheric locations were accelerated by this shock or
whether transport mechanisms in the corona and/or interplanetary space
provide an alternative explanation for the arrival of particles at the
poorly connected spacecraft. A possible scenario consistent with the
observations indicates that the observation of SEPs at STEREO-B and near
Earth resulted from particle injection by the CME shock onto the field
lines connecting to these spacecraft, whereas SEPs reached STEREO-A
mostly via cross-field diffusive transport processes. The successes,
limitations, and uncertainties of the methods used to resolve the
connection between the acceleration sites of SEPs and the spacecraft
are evaluated.
Title: Geosynchronous Patrol Orbit for Space Situational Awareness
Authors: Thompson, B.; Kelecy, T.; Kubancik, T.; Flora, T.; Chylla,
M.; Rose, D.
Bibcode: 2017amos.confE..96T
Altcode:
Applying eccentricity to a geosynchronous orbit produces
both longitudinal and radial motion when viewed in Earth-fixed
coordinates. An interesting family of orbits emerges, useful for
“neighborhood patrol” space situational awareness and other
missions. The basic result is a periodic (daily), quasielliptical,
closed path around a fixed region of the geosynchronous (geo) orbit
belt, keeping a sensor spacecraft in relatively close vicinity to
designated geo objects. The motion is similar, in some regards, to the
relative motion that may be encountered during spacecraft proximity
operations, but on a much larger scale. The patrol orbit does not
occupy a fixed slot in the geo belt, and the east-west motion can be
combined with north-south motion caused by orbital inclination, leading
to even greater versatility. Some practical uses of the geo patrol
orbit include space surveillance (including catalog maintenance), and
general space situational awareness. The patrol orbit offers improved,
diverse observation geometry for angles-only sensors, resulting in
faster, more accurate orbit determination compared to simple inclined
geo orbits. In this paper, we analyze the requirements for putting a
spacecraft in a patrol orbit, the unique station keeping requirements
to compensate for perturbations, repositioning the patrol orbit to
a different location along the geo belt, maneuvering into, around,
and out of the volume for proximity operations with objects within
the volume, and safe end-of-life disposal requirements.
Title: Connectivity Between Solar Energetic Particle Observations
and Their Solar Sources: The Event on 14 August 2010
Authors: Kwon, R. Y.; Makela, P. A.; Lario, D.; Raouafi, N. E.;
Thompson, B. J.; Richardson, I. G.; von Rosenvinge, T. T.; Xie, H.;
Mays, M. L.; Thakur, N.; Bain, H. M.; Zhang, M.; Zhao, L.; Matthaeus,
W. H.; Papaioannou, A.; Riley, P.
Bibcode: 2016AGUFMSH41B2530K
Altcode:
We analyze one of the first multi-spacecraft solar energetic particle
(SEP) events of solar cycle 24 to assess the reliability of models
currently used to determine the connectivity between the sources of SEPs
at the Sun and spacecraft located in the inner heliosphere. This SEP
event was observed on 14 August 2010 by near-Earth spacecraft, STEREO-A
(at 0.96 AU from the Sun and 80° west of Earth) and STEREO-B (at 1.07
AU and 72° east of Earth). The SEP event occurred in association with
a C4.4 flare at N13W54 (as seen from Earth) and a fast ( 1200 km s-1)
halo coronal mass ejection (CME). Whereas near-Earth observers were
magnetically connected to the site of the active region, the other
spacecraft observing SEPs remained poorly connected to the active
region. We discuss the properties of the phenomena associated with the
solar eruption as seen in extreme ultraviolet and white-light images
collected by SOHO, SDO and STEREO that allow us to specify the extent of
the coronal shock associated with the CME and whether the SEPs observed
at the three heliospheric locations were accelerated and injected by the
shock. Alternatively, we study whether transport mechanisms in the solar
corona and/or interplanetary space explain the arrival of particles
to those spacecraft poorly connected to the particle sources. Finally,
we discuss whether the large-scale physics-based prediction models of
the heliosphere, currently used by the Space Weather Forecast Offices
at NOAA and NASA/GSFC, provide a good description for the connectivity
of each spacecraft with the particle sources in interplanetary space.
Title: Dynamic Mapping of Coronal Activity
Authors: Thompson, B. J.; Uritsky, V. M.; Ireland, J.; Young, C. A.;
Kirk, M. S.
Bibcode: 2016AGUFMSH11A2224T
Altcode:
There is a great deal of variation in how CMEs are manifested in
EUV and coronagraph images. Complicating the issue is the range
of CME-associated phenomena: shocks, waves, prominences, flares,
dimmings, to name a few. None of these phenomena are a necessary
or sufficient condition for a CME. However, each can provide clues
as to CME origin, topology, and kinematics. New analysis strategies
have been devised specifically to extract key properties of CMEs and
CME-associated phenomena, with results that are converging towards
a more consistent model of solar eruptive menagerie. We will discuss
techniques such as Persistence Mapping and Time Convolution mapping,
and how they are used to extract the dynamics of eruptive phenomena.
Title: Asymmetries in Solar Particle Events: Are They Related to
Dimming Region Asymmetries Relative to Flares?
Authors: Richardson, I. G.; Thompson, B. J.; von Rosenvinge, T. T.
Bibcode: 2016AGUFMSH32A..03R
Altcode:
Studies of the longitudinal distribution of solar energetic particles
generally use the location of the related solar flare as a reference
longitude. In particular, particle intensities are typically found
to fall off with increasing "connection angle" - the longitudinal
separation between the flare and the footpoint of the field line
passing the observing spacecraft - and are often fitted by Gaussians
in connection angle. Although the peak of the Gaussian is often close
to zero connection angle, i.e., on field lines connecting close to
the flare longitude, some 25 MeV proton events observed by both STEREO
spacecraft and at the Earth show clear asymmetries, either to the east
or west relative to the flare longitude, in their early stages. There
are various possible reasons for such asymmetries, one being that
the flare longitude may not represent the expansion direction of the
coronal mass ejection and associated shock, which may accelerate the
particles. Since coronal dimming regions lie below CMEs, and dimmings
may form asymmetrically relative to flares, we use the centroid of a
dimming region as a proxy for CME direction and examine whether there is
any relationship between the east-west asymmetry in the dimming relative
to the flare and the longitudinal asymmetry in the related SEP event.
Title: Dynamic Mapping of Prominence Activity
Authors: Thompson, Barbara J.; Gilbert, Holly R.; Kirk, Michael
S.; Mays, M. Leila.; Ofman, Leon; Uritsky, Vadim; Wyper, Peter;
Hovis-Afflerbach, Beryl
Bibcode: 2016usc..confE..82T
Altcode:
We present the results of a prominence mapping effort designed to
extract the dynamics of erupting prominences. The material from
partially erupting prominences can fall back to the sun, tracing
out the topology of the mid- and post-eruptive corona. One question
involving the range of observed behavior is the role of magnetic
field topology and evolution in determining the motion of the erupting
prominence material. A variable-g ballistic approximation is applied
to study the motion of the material, using the deviations from constant
angular momentum as a means of quantifying the local Lorentz (and other)
forces on each piece of material. Variations in dynamic behavior can be
traced back to changes in the local magnetic field and the formation
of instabilities such as Rayleigh-Taylor. We discuss the use of the
prominence trajectories as a means of diagnosing eruptive topologies.
Title: Image-based reconstruction of the Newtonian dynamics of solar
coronal ejecta
Authors: Uritsky, Vadim M.; Thompson, Barbara J.
Bibcode: 2016usc..confE.126U
Altcode:
We present a new methodology for analyzing rising and falling dynamics
of unstable coronal material as represented by high-cadence SDO AIA
images. The technique involves an adaptive spatiotemporal tracking of
propagating intensity gradients and their characterization in terms
of time-evolving areas swept out by the position vector originated
from the Sun disk center. The measured values of the areal velocity
and acceleration are used to obtain quantitative information on
the angular momentum and acceleration along the paths of the rising
and falling coronal plasma. In the absence of other forces, solar
gravitation results in purely ballistic motions consistent with the
Kepler's second law; non-central forces such as the Lorentz force
introduce non-zero torques resulting in more complex motions. The
developed algorithms enable direct evaluation of the line-of-sight
component of the net torque applied to a unit mass of the ejected
coronal material which is proportional to the image-plane projection
of the observed areal acceleration. The current implementation of
the method cannot reliably distinguish torque modulations caused
by the coronal force field from those imposed by abrupt changes
of plasma mass density and nontrivial projection effects. However,
it can provide valid observational constraints on the evolution of
large-scale unstable magnetic topologies driving major solar-coronal
eruptions as demonstrated in the related talk by B. Thompson et al.
Title: AWARE - The Automated EUV Wave Analysis and REduction algorithm
Authors: Ireland, J.; Inglis; A. R.; Shih, A. Y.; Christe, S.; Mumford,
S.; Hayes, L. A.; Thompson, B. J.
Bibcode: 2016usc..confE..59I
Altcode:
Extreme ultraviolet (EUV) waves are large-scale propagating disturbances
observed in the solar corona, frequently associated with coronal
mass ejections and flares. Since their discovery over two hundred
papers discussing their properties, causes and physics have been
published. However, their fundamental nature and the physics of their
interactions with other solar phenomena are still not understood. To
further the understanding of EUV waves, and their relation to other
solar phenomena, we have constructed the Automated Wave Analysis and
REduction (AWARE) algorithm for the detection of EUV waves over the full
Sun. The AWARE algorithm is based on a novel image processing approach
to isolating the bright wavefront of the EUV as it propagates across
the corona. AWARE detects the presence of a wavefront, and measures
the distance, velocity and acceleration of that wavefront across the
Sun. Results from AWARE are compared to results from other algorithms
for some well known EUV wave events. Suggestions are also give for
further refinements to the basic algorithm presented here.
Title: Relationship of EUV Irradiance Coronal Dimming Slope and
Depth to Coronal Mass Ejection Speed and Mass
Authors: Mason, James Paul; Woods, Thomas N.; Webb, David F.; Thompson,
Barbara J.; Colaninno, Robin C.; Vourlidas, Angelos
Bibcode: 2016ApJ...830...20M
Altcode: 2016arXiv160705284M
Extreme ultraviolet (EUV) coronal dimmings are often observed in
response to solar eruptive events. These phenomena can be generated
via several different physical processes. For space weather, the most
important of these is the temporary void left behind by a coronal mass
ejection (CME). Massive, fast CMEs tend to leave behind a darker void
that also usually corresponds to minimum irradiance for the cooler
coronal emissions. If the dimming is associated with a solar flare,
as is often the case, the flare component of the irradiance light
curve in the cooler coronal emission can be isolated and removed
using simultaneous measurements of warmer coronal lines. We apply
this technique to 37 dimming events identified during two separate
two-week periods in 2011 plus an event on 2010 August 7, analyzed in a
previous paper to parameterize dimming in terms of depth and slope. We
provide statistics on which combination of wavelengths worked best
for the flare-removal method, describe the fitting methods applied
to the dimming light curves, and compare the dimming parameters
with corresponding CME parameters of mass and speed. The best linear
relationships found are v CME km s ≈ 2.36 × 10 6 km % × s dim % s
m CME [ g ] ≈ 2.59 × 10 15 g % × d dim [ % ] . These relationships
could be used for space weather operations of estimating CME mass and
speed using near-real-time irradiance dimming measurements.
Title: SDO 2016: Unraveling the Suns Complexity
Authors: Pesnell, W. Dean; Thompson, Barbara
Bibcode: 2016usc..conf.....P
Altcode:
Living With a Star Solar Dynamics Observatory research connects to many
areas of solar physics and many other solar missions. Tracing these
connections allows us to build a more accurate understanding of the Sun
and solar activity. The workshop will focus on our improved knowledge
and understanding of the Suns magnetic field that have come from the
SDO data, and what will come in the future. Scientific sessions will
feature a broad spectrum of science topics fundamental to SDO science
investigations: Atmospheric Imaging Assembly (AIA), EUV Variability
Experiment (EVE), and Helioseismic and Magnetic Imager (HMI), as
well as the overlap between SDO and other scientific missions and
activities. We invite you to celebrate the breadth of research topics
enabled by SDO during its Prime Mission and the First Extended Mission.
Title: Chemical abundance gradients from open clusters in the Milky
Way disk: Results from the APOGEE survey
Authors: Cunha, K.; Frinchaboy, P. M.; Souto, D.; Thompson, B.;
Zasowski, G.; Allende Prieto, C.; Carrera, R.; Chiappini, C.; Donor,
J.; García-Hernández, D. A.; García Pérez, A. E.; Hayden, M. R.;
Holtzman, J.; Jackson, K. M.; Johnson, J. A.; Majewski, S. R.;
Mészáros, S.; Meyer, B.; Nidever, D. L.; O'Connell, J.; Schiavon,
R. P.; Schultheis, M.; Shetrone, M.; Simmons, A.; Smith, V. V.; et al.
Bibcode: 2016AN....337..922C
Altcode: 2016arXiv160103099C
Metallicity gradients provide strong constraints for understanding
the chemical evolution of the Galaxy. We report on radial abundance
gradients of Fe, Ni, Ca, Si, and Mg obtained from a sample of 304
red-giant members of 29 disk open clusters, mostly concentrated
at galactocentric distances between ∼ 8-15 kpc, but including
two open clusters in the outer disk. The observations are from the
APOGEE survey. The chemical abundances were derived automatically by
the ASPCAP pipeline and these are part of the SDSS III Data Release
12. The gradients, obtained from least squares fits to the data,
are relatively flat, with slopes ranging from -0.026 to -0.033 dex
kpc-1 for the α-elements [O/H], [Ca/H], [Si/H], and [Mg/H],
and -0.035 dex kpc-1 and -0.040 dex kpc-1 for
[Fe/H] and [Ni/H], respectively. Our results are not at odds with
the possibility that metallicity ([Fe/H]) gradients are steeper in
the inner disk ({R_GC∼ 7}-12 kpc) and flatter towards the outer
disk. The open cluster sample studied spans a significant range in
age. When breaking the sample into age bins, there is some indication
that the younger open cluster population in our sample (log age <
8.7) has a flatter metallicity gradient when compared with the gradients
obtained from older open clusters.
Title: Asymmetries in Solar Particle Events: Are They Related to
Dimming Region Asymmetries Relative to Flares?
Authors: Richardson, Ian; Thompson, Barbara J.; von Rosenvinge,
Tycho T.
Bibcode: 2016shin.confE..22R
Altcode:
Studies of the longitudinal distribution of solar energetic particles
have typically assumed the location of the related solar flare as a
reference longitude. For example, intensities observed at spacecraft are
typically mapped back to the Sun along Parker spiral field lines (often
with some modification near the Sun given by a coronal field model) and
the resulting 'connection angle' between the flare location and field
line foot point is then obtained. Particle intensities typically fall
off with increasing connection angle, and are often fitted by Gaussians
in connection angle. Frequently, the peak of the Gaussian is close to
zero connection angle, i.e., the largest particle intensities occur on
field lines connecting close to the flare longitude. However, we find
that some 25 MeV proton events observed by the two STEREO spacecraft
and at the Earth show significant asymmetries either to the east or
west relative to the flare longitude. One possible contributor is that
the flare longitude may not represent the expansion direction of the
CME. Recent results indicate that coronal dimming regions lie below
CMEs, and dimmings may form asymmetrically relative to flares. Using the
centroid of a dimming region as a proxy for CME direction, we examine
whether there is any relationship between the east-west asymmetry in
the dimming relative to the flare and the longitudinal asymmetry in
the related SEP event.
Title: Dimmings as a footprint of coronal mass ejections
Authors: Thompson, Barbara J.; Allred, Joel C.; Kay, Christina;
Nieves-Chinchilla, Teresa
Bibcode: 2016shin.confE..55T
Altcode:
Large regions of coronal dimming often accompany coronal mass ejections
(CMEs). Of all of the EUV signatures of CMEs, dimmings (when present)
are the best match to the location and extent of the coronagraph
CME observations. They last on timescales from minutes to hours, are
sometimes patchy in appearance, and can extend far (>1 RSun) from
the flaring region. They are known to be good indicators of the site
of evacuated material, and have been extensively studied as a CME mass
source. We investigate the possibility that dimmings also serve as a
magnetic footprint of CMEs. Dimmings develop during or soon after the
eruption, and may trace field lines locally opened during the CME. These
dimming regions can be extensive, representing at least part of the
'base' of a CME and the mass and magnetic flux transported outward by
it. We report on three-dimensional observations of the co- development
of dimmings in EUV and coronagraph images, magnetic field topologies
represented by the dimmings, and (when available) in situ observations
that can be used as a diagnostic of the erupting field topology.
Title: Dynamic Mapping of Prominence Activity
Authors: Thompson, Barbara J.; Uritsky, Vadim; Ofman, Leon
Bibcode: 2016shin.confE.141T
Altcode:
We present the results of a prominence mapping effort designed to
extract the dynamics of both erupting and quiescent prominences. The
material from partially erupting prominences can fall back to the sun,
tracing out the topology of the post-eruptive corona. A variable-g
ballistic approximation is applied to study the motion of the material,
using the deviations from constant angular momentum as a means of
quantifying the local Lorentz (and other) forces on each piece of
material. Variations in dynamic behavior can be traced back to changes
in the local magnetic field and the formation of instabilities such
as Rayleigh-Taylor.
Title: Persistence Mapping Using EUV Solar Imager Data
Authors: Thompson, B. J.; Young, C. A.
Bibcode: 2016ApJ...825...27T
Altcode:
We describe a simple image processing technique that is useful for
the visualization and depiction of gradually evolving or intermittent
structures in solar physics extreme-ultraviolet imagery. The technique
is an application of image segmentation, which we call “Persistence
Mapping,” to isolate extreme values in a data set, and is particularly
useful for the problem of capturing phenomena that are evolving in both
space and time. While integration or “time-lapse” imaging uses the
full sample (of size N ), Persistence Mapping rejects (N - 1)/N of the
data set and identifies the most relevant 1/N values using the following
rule: if a pixel reaches an extreme value, it retains that value until
that value is exceeded. The simplest examples isolate minima and maxima,
but any quantile or statistic can be used. This paper demonstrates
how the technique has been used to extract the dynamics in long-term
evolution of comet tails, erupting material, and EUV dimming regions.
Title: About Steady and Transient States During Two Long Intervals
of Extremely Low Speed Solar Wind Speed Observed by STEREO and Wind
Authors: Berdichevsky, Daniel Benjamin; Galvin, A. B.; Farrugia,
C. J.; Thompson, B. J.; Vasquez, B.; Simunac, K. D. C.
Bibcode: 2016shin.confE..76B
Altcode:
The passage of a solar wind stream extending from October 24 to 30,
2010, was well monitored, ahead of arrival at Earth's location of a
possible corotating stream, with the help of the STEREO-A instruments
IMPACT and PLASTIC. This was an extremely slow flow which exhibited the
following features a. An interval of over 2 days of speeds below
250 km/s b. At the start, an expanding magnetic cloud interval
lasting about 14 hrs. c. The presence of distinct ratios in charge
states suggesting presence of transient material in and outside the
magnetic cloud. d. The presence in the plasma of a sizeable amount
of He++ which we compare with the predictions made at the observed
SW speed. We check with Lopez (1987) the observed and predicted
estimates of the thermal velocity of the protons observed for the
interval. In addition, we present the implication on the Parker model
for the possible temperature of the corona assuming the dominant aspects
of the outflow correspond to the case of an steady solar wind. The
lack of passage of the event near Earth location is discussed, and its
implications regarding the spatial extent of the solar outflow and the
nature of its overall origin is assessed. Although not on year 2010,
at the Lagrangian point L1, we observe with Wind the occurrence in
years 2007 to 2009 of several intervals of low speed solar wind, of
which for a comparison we select the low solar wind interval starting
Dec 8, 2009 and which continued for more than 5 days. The interval at
Wind has a similar extension as the one at STEREO-A. This includes the
presence of a MC. Charge states are compared as well as the presence
of the alpha-to-proton number density ratio
Title: Dimmings as a footprint of coronal mass ejections
Authors: Thompson, Barbara J.; Allred, Joel C.; Kay, Christina;
Krista, Larisza Diana; Mason, James; Nieves-Chinchilla, Teresa;
Reinard, Alysha; Webb, David F.
Bibcode: 2016SPD....4710601T
Altcode:
Large regions of coronal dimming often accompany coronal mass ejections
(CMEs). Of all of the EUV signatures of CMEs, dimmings (when present)
are the best match to the location and extent of the coronagraph
CME observations. They last on timescales from minutes to hours, are
sometimes patchy in appearance, and can extend far (>1 RSun) from
the flaring region. They are known to be good indicators of the site
of evacuated material, and have been extensively studied as a CME mass
source. We investigate the possibility that dimmings also serve as a
magnetic footprint of CMEs. Dimmings develop during or soon after the
eruption, and may trace field lines locally opened during the CME. These
dimming regions can be extensive, representing at least part of the
“base” of a CME and the mass and magnetic flux transported outward
by it. We report on three-dimensional observations of the co-development
of dimmings in EUV and coronagraph images, magnetic field topologies
represented by the dimmings, and (when available) in situ observations
that can be used as a diagnostic of the erupting field topology.
Title: ENLIL Global Heliospheric Modeling as a Context For Multipoint
Observations
Authors: Mays, M. Leila; Odstrcil, Dusan; Luhmann, Janet; Bain, Hazel;
Li, Yan; Schwadron, Nathan; Gorby, Matt; Thompson, Barbara; Jian,
Lan; Möstl, Christian; Rouillard, Alexis; Davies, Jackie; Temmer,
Manuela; Rastaetter, Lutz; Taktakishvili, Aleksandre; MacNeice, Peter;
Kuznetsova, Maria
Bibcode: 2016EGUGA..1811638M
Altcode:
We present heliospheric simulation case studies using recent
enhancements to WSA--ENLIL+Cone (version 2.8) at the Community
Coordinated Modeling Center (CCMC). The global 3D MHD ENLIL model
provides a time-dependent description of the background solar wind
plasma and magnetic field using a sequence of WSA coronal model
maps as input at the inner boundary of 21.5 Rs. A homogeneous,
over-pressured hydrodynamic plasma cloud is launched through the
inner boundary of the heliospheric computational domain and into
the background solar wind. Multipoint observations help constrain
simulations and this modeling system provides global context and
arrival times of the solar wind streams and CMEs at Earth, planets,
and spacecraft. Additionally, one can extract the magnetic topologies
of observer-connected magnetic field lines and all plasma and shock
properties along those field lines. ENLIL "likelihood/all-clear"
forecasting maps provide expected intensity, timing/duration of events
at locations throughout the heliosphere with "possible SEP affected
areas" color-coded based on shock strength. ENLIL simulations are also
useful to drive SEP models such as the Solar Energetic Particle Model
(SEPMOD) (Luhmann et al. 2007, 2010) and Energetic Particle Radiation
Environment Module (EPREM) (Schwadron et al., 2010). SEPMOD injects
protons onto a sequence observer field lines at intensities dependent
on the connected shock source strength which are then integrated at
the observer to approximate the proton flux. EPREM couples with MHD
models such as ENLIL and computes energetic particle distributions
based on the focused transport equation along a Lagrangian grid of
nodes that propagate out with the solar wind. Studies have shown
that accurate descriptions of the heliosphere, and hence modeled CME
arrival times and SEPs, are achieved by ENLIL only when the background
solar wind is well-reproduced and CME parameters are accurate. It is
essential to include all of the relevant CMEs and allow enough time
for the events to propagate and interact. In this presentation we
demonstrate several event case studies of ENLIL simulations compared
with multipoint observations, exploring the background solar wind and
CME pre-conditioning, and including comparisons between ENLIL synthetic
j-maps with observed STEREO/HI j-maps using catalogues from the HELCATS
FP7 project.
Title: Deriving Kinematic Properties of Non-Radial, Asymmetric and
Deflecting CMEs: Methods and Implications
Authors: Thompson, B. J.; Liewer, P. C.; Mays, M. L.; Richardson,
I. G.; Kwon, R.; Ofman, L.; Makela, P. A.; Ireland, J.; Hess, P.;
Waldron, Z.
Bibcode: 2015AGUFMSH33B2467T
Altcode:
An improved understanding of the kinematic properties of CMEs and
CME-associated phenomena has several impacts: 1) a less ambiguous
method of mapping propagating structures into their inner coronal
manifestations, 2) a clearer view of the relationship between the
"main" CME and CME-associated brightenings, and 3) an improved
identification of the heliospheric sources of shocks, Type II bursts,
and SEPs. However, there are several challenges in characterizing
the kinematic properties of CMEs. Most rapidly-evolving eruptions are
accompanied by changes in the surrounding corona. The larger the impact
on the surrounding corona, the more difficult it is to separate the
"main" CME from the CME-associated brightenings. Complicating the
issue is the range of observed propagation properties: super-radial
expansion, asymmetric expansion, non-radial propagation, and alterations
in the direction of propagation. These properties can be a function
of both the internal magnetic structure of the CME and the structure
of the corona through which the CME is propagating. While the relative
contribution of internal/external factors can be difficult to assess,
it is of fundamental importance because it not only reveals the nature
of CMEs but also CME-associated phenomena such as EUV waves, Type
II radio bursts, shocks, and SEPs. Most halo CMEs are a combination
of both the "main" CME and the CME-associated brightenings, but
new diagnostic methods such as time convolution mapping can help
separate the CME mass from the impacted corona. Additionally, while
most CME-fitting methods assume symmetry about the radial direction,
adaptive methods allow us to study highly asymmetric CME expansion
and take into account the fundamentally different natures of the CME
and the shocked/deflected corona. Several methods will be examined,
and each has their respective strengths and weaknesses; for example,
the difference between the direction of a highly non-radial CME and a
sun-centered model's orientation can exceed 45 degrees, which impacts
our ability to correctly assess changes in propagation direction and
the causes of these changes. We examine the assumptions inherent in
these methods and how they may produce artifacts that can influence
conclusions about CME kinematics.
Title: On the Structure of a Long Interval of Extremely Low Speed
Solar Wind Observed by STEREO, and Comparison to Similar Events in
the Same Solar Cycle
Authors: Berdichevsky, D. B.; Galvin, A. B.; Farrugia, C. J.; Thompson,
B. J.
Bibcode: 2015AGUFMSH23A2430B
Altcode:
The passage of a solar wind stream extending from October 24 to 30,
2010, with its magnetized plasma was well monitored, ahead of Earth's
location arrival of a possible corotating stream, with the help of the
STEREO-A instruments IMPACT and PLASTIC. This was an extremely slow
flow which exhibited the following features a. An interval of over
2 days showing a solar wind speed below 250 km/s b. At the start,
an expanding magnetic cloud interval lasting about 14 hrs. c. The
presence of distinct ratios in charge states suggesting presence
of transient at material in and outside the magnetic cloud. d. The
presence in the plasma of a sizeable amount of He++ which we compare
with the predictions made at the observed SW speed. We check with Lopez
(1987) the observed and predicted estimates of the thermal velocity
of the protons observed for the interval. In addition we present the
implication on the parker model for the possible temperature of the
corona assuming the dominant aspects of the outflow correspond to
the case of an steady solar wind. The lack of passage of the event
near Earth location is discussed, and its implications regarding
its extension in space of the solar outflow and the nature of its
overall origin is assessed. Although not on the same year 2010, at the
Lagrangian point L1, we observe with Wind the occurrence in 2007 to 2009
of several intervals of low speed solar wind, of which for a comparison
we select the two low solar wind intervals starting Nov 29, and Dec 8,
2009 which extended over more than 5 days each. These intervals at
Wind have a similar extension as the one at STEREO-A. However, the
presence of a MC or not are less clear for these cases. Also charge
states are compared as well as the presence of the alpha--to--proton
number density ratio.
Title: Survey of high-altitude partially erupting prominences
Authors: Gilbert, H. R.; St Cyr, O. C.; Thompson, B. J.; Inglis,
A. R.; Xie, H.
Bibcode: 2015AGUFMSH53B2490G
Altcode:
Solar prominences exhibit a range of eruptive-like dynamic activity,
including in some cases the confined or 'failed' ejection of prominence
material from the solar atmosphere. Many prominences exhibit a partial
eruption in which some mass escapes while the remaining mass drains
back to the photosphere. This process may involve the formation of an
X-type neutral line in this region, which allows disconnection of part
of the prominence material. In a previous study (Gilbert et al. 2000)
it was found that this separation tends to occur in the height range
from 1.20 to 1.35 Rsun. More recently, the separation point in these
types of partial eruptions has been observed to occur at much larger
heights. We investigate a selection of these higher partial eruptions,
exploring the characteristics of the prominences and their associated
CMEs to better understand the dynamical processes in the solar
atmosphere associated with eruption.
Title: Propagation of the 7 January 2014 CME and Resulting Geomagnetic
Non-event
Authors: Mays, M. L.; Thompson, B. J.; Jian, L. K.; Colaninno, R. C.;
Odstrcil, D.; Möstl, C.; Temmer, M.; Savani, N. P.; Collinson, G.;
Taktakishvili, A.; MacNeice, P. J.; Zheng, Y.
Bibcode: 2015ApJ...812..145M
Altcode: 2015arXiv150906477M
On 2014 January 7 an X1.2 flare and coronal mass ejection (CME) with a
radial speed ≈2500 km s-1 was observed from near an active
region close to disk center. This led many forecasters to estimate a
rapid arrival at Earth (≈36 hr) and predict a strong geomagnetic
storm. However, only a glancing CME arrival was observed at Earth
with a transit time of ≈49 hr and a K P geomagnetic
index of only 3-. We study the interplanetary propagation of this
CME using the ensemble Wang-Sheeley-Arge (WSA)-ENLIL+Cone model,
that allows a sampling of CME parameter uncertainties. We explore a
series of simulations to isolate the effects of the background solar
wind solution, CME shape, tilt, location, size, and speed, and the
results are compared with observed in situ arrivals at Venus, Earth,
and Mars. Our results show that a tilted ellipsoid CME shape improves
the initial real-time prediction to better reflect the observed in situ
signatures and the geomagnetic storm strength. CME parameters from the
Graduated Cylindrical Shell model used as input to WSA-ENLIL+Cone, along
with a tilted ellipsoid cloud shape, improve the arrival-time error
by 14.5, 18.7, 23.4 hr for Venus, Earth, and Mars respectively. These
results highlight that CME orientation and directionality with respect
to observatories play an important role in understanding the propagation
of this CME, and for forecasting other glancing CME arrivals. This study
also demonstrates the importance of three-dimensional CME fitting made
possible by multiple viewpoint imaging.
Title: False Alarm Rate in Predicting the Longitudinal Dependence
of SEP Intensity
Authors: Mays, M. Leila; Richardson, I. G.; Thompson, B. J.
Bibcode: 2015shin.confE.165M
Altcode:
Richardson et al. (Solar Physics, 2014, 289:8) studied the longitudinal
dependence of >25 MeV solar proton events observed by multiple
spacecraft from December 2009 -December 2012, together with their solar
sources. Gaussian fits to the peak SEP intensity observed by multiple
spacecraft versus the connection angle (phi) were combined together
with the correlation of the peak intensity with the associated CME
speed V, leading to an equation for the 14 - 24 MeV proton intensity: I
(phi) (MeV s cm2 sr)?1 = 0.013 exp(0.0036V ?phi^2/2σ^2). In this
work we apply this equation to approximately 100 CMEs which have
been associated with flares from 2010-2015 in the DONKI database
which consists of CME measurements performed real-time by CCMC/SWRC
(http://kauai.ccmc.gsfc.nasa.gov/DONKI/). We compare the predicted SEP
intensities with those observed and examine the false alarm rate and
whether radio bursts are a useful discriminator to reduce false alarms.
Title: The Space Weather Research Laboratory 'Research To Operations'
(R2O) Mini-Workshop Program
Authors: Thompson, Barbara J.; Friedl, L. A.; Kuznetsova, M.; Mays,
M. L.; Nieves-Chinchilla, T.; Pulkkinen, A. A.; Richardson, I. G.;
Stehr, J. W.; Zesta, E.; Zheng, Y.
Bibcode: 2015shin.confE.169T
Altcode:
The Space Weather Research to Operations (R2O) Working Group is hosted
by NASA GSFC's Heliophysics Science Division (HSD), but participants
from outside organizations and institutions also play important
roles. The focus of the R2O Working Group is to capitalize on the
research and knowledge of scientists who are not forecasters, and
improve their awareness of forecasting and research needs. Although
there are many research results that are directly related to space
weather, there is a need to help non-forecasters communicate new results
to forecasters and turn scientific advances into ingestible products
by forecasting operations. The R2O program organizes a series
of theme-focused workshops in order to quickly advance communication
in each themed topic. Each R2O mini-workshop is an open forum where
operations experts, forecasters and researchers discuss the state of the
knowledge of a chosen space weather research topic. The discussion then
moves to which aspects of current research activities have potential
to be used in space weather forecasting. The goal is to be broad yet
comprehensive, with the aim of determining which items have the greatest
potential for space weather development. The ultimate goal is
to produce tools and products that can easily be added to operations
and improve forecasts. Team members are able to identify topics that
require further collaboration and research, but have great potential
in the long-term to provide useful tools. Many continue the effort by
publishing research papers on the topic or choosing to seek support
through a proposal. A useful tool to guide the discussions is the
concept of 'Application Readiness Levels' (ARLs) developed by the NASA
Earth Science Applications Office. ARLs parallel Technology Readiness
Levels (TRLs), and allow us to assess different areas of knowledge
and research and keep track of how close to 'full implementation'
a given model or data analysis effort is. A final aspect of this
discussion is the reverse stream of information, namely Operations to
Research (O2R). O2R includes the feedback of operational environment to
guide research goals, the use of operational assets to enable research,
and the use of an operational environment to validate, question, and
refine research efforts. A healthy circle based on R2O-O2R activities
means that the operational and research communities have formed a
successful, close-looped partnership, are aware of the other's needs,
and are making steps towards improvement. In the O2R environment,
forecasters are not passive recipients of scientific knowledge;
they actively work with the research community to refine and develop
new research goals. A major driver of the popularity of the annual
'Space Weather Workshops' hosted by the Space Weather Research Center
in Boulder, CO is due to this beneficial relationship.
Title: Predicting the magnetic vectors within coronal mass ejections
arriving at Earth: 1. Initial architecture
Authors: Savani, N. P.; Vourlidas, A.; Szabo, A.; Mays, M. L.;
Richardson, I. G.; Thompson, B. J.; Pulkkinen, A.; Evans, R.;
Nieves-Chinchilla, T.
Bibcode: 2015SpWea..13..374S
Altcode: 2015arXiv150202067S
The process by which the Sun affects the terrestrial environment
on short timescales is predominately driven by the amount
of magnetic reconnection between the solar wind and Earth's
magnetosphere. Reconnection occurs most efficiently when the solar
wind magnetic field has a southward component. The most severe impacts
are during the arrival of a coronal mass ejection (CME) when the
magnetosphere is both compressed and magnetically connected to the
heliospheric environment. Unfortunately, forecasting magnetic vectors
within coronal mass ejections remain elusive. Here we report how,
by combining a statistically robust helicity rule for a CME's solar
origin with a simplified flux rope topology, the magnetic vectors
within the Earth-directed segment of a CME can be predicted. In
order to test the validity of this proof-of-concept architecture for
estimating the magnetic vectors within CMEs, a total of eight CME
events (between 2010 and 2014) have been investigated. With a focus
on the large false alarm of January 2014, this work highlights the
importance of including the early evolutionary effects of a CME for
forecasting purposes. The angular rotation in the predicted magnetic
field closely follows the broad rotational structure seen within the
in situ data. This time-varying field estimate is implemented into
a process to quantitatively predict a time-varying Kp index that is
described in detail in paper II. Future statistical work, quantifying
the uncertainties in this process, may improve the more heuristic
approach used by early forecasting systems.
Title: What Do EUV Dimmings Tell Us About CME Topology
Authors: Thompson, Barbara J.; DeRosa, Marc L.; Fisher, Richard R.;
Krista, Larisza D.; Kwon, Ryun Young; Mason, James P.; Mays, Mona L.;
Nitta, Nariaki V.; Webb, David F.; West, Matthew J.
Bibcode: 2015TESS....121201T
Altcode:
Large-scale coronal EUV dimmings develop on timescales of hours in
association with a flare or filament eruption, and are known to be
well correlated with coronal mass ejections (CMEs). However, it is not
clear why some CMEs have dimmings and some do not, nor is it clear how
these dimmings relate to CME topology. The inner coronal coverage of
SDO AIA and STEREO EUVI, combined with the extended field of view of
PROBA2's SWAP imager, allow us the opportunity to map the topology of
a dimming region in three dimensions into an erupting CME. Although
the location and extent of a dimming region appears to be the best
indicator of the inner "footprint" of a CME, the correlation is far
from perfect. However, dimmings can provide vital clues about the
development and 3D kinematics of CMEs. This is particularly important
as we are currently in an extended period where the STEREO coronagraph
images are not always available and are increasingly "mirroring" LASCO
images, and therefore the 3D properties of a CME will be difficult
to deduce. Thus, understanding the inner coronal manifestations of
a CME can provide clues to its structure and dynamics, even without
multi-viewpoint coronagraph observations. We present the results of
this combined analysis effort, along with a discussion of how dimmings
can be used to forecast CME trajectories.
Title: Survey of high-altitude partially erupting prominences
Authors: Gilbert, Holly; St Cyr, O. C.; Inglis, Andrew; Xie, Hong;
Thompson, Barbara J.
Bibcode: 2015TESS....120316G
Altcode:
Solar prominences exhibit a range of eruptive-like dynamic activity,
including in some cases the confined or 'failed' ejection of prominence
material from the solar atmosphere. Many prominences exhibit a partial
eruption in which some mass escapes while the remaining mass drains
back to the photosphere. This process may involve the formation of an
X-type neutral line in this region, which allows disconnection of part
of the prominence material. In a previous study (Gilbert et al. 2000)
it was found that this separation tends to occur in the height range
from 1.20 to 1.35 Rsun. More recently, the separation point
in these types of partial eruptions has been observed to occur at much
larger heights. We investigate a selection of these higher partial
eruptions, exploring the characteristics of the prominences and their
associated CMEs to better understand the dynamical processes in the
solar atmosphere associated with eruption.
Title: STEREO as a 'Planetary Hazards' Mission
Authors: Guhathakurta, M.; Thompson, B. J.
Bibcode: 2015hchp.book..197G
Altcode:
No abstract at ADS
Title: NASA Space Weather Research Center: Addressing the Unique
Space Weather Needs of NASA Robotic Missions
Authors: Zheng, Y.; Pulkkinen, A. A.; Kuznetsova, M. M.; Maddox,
M. M.; Mays, M. L.; Taktakishvili, A.; Chulaki, A.; Thompson, B. J.;
Collado-Vega, Y. M.; Muglach, K.; Evans, R. M.; Wiegand, C.; MacNeice,
P. J.; Rastaetter, L.
Bibcode: 2014AGUFMSM31A4151Z
Altcode:
The Space Weather Research Center (SWRC) has been providing space
weather monitoring and forecasting services to NASA's robotic
missions since its establishment in 2010. Embedded within the Community
Coordinated Modeling Center (CCMC) (see Maddox et al. in Session IN026)
and located at NASA Goddard Space Flight Center, SWRC has easy access
to state-of-the-art modeling capabilities and proximity to space science
and research expertise. By bridging space weather users and the research
community, SWRC has been a catalyst for the efficient transition from
research to operations and operations to research. In this presentation,
we highlight a few unique aspects of SWRC's space weather services,
such as addressing space weather throughout the solar system, pushing
the frontier of space weather forecasting via the ensemble approach,
providing direct personnel and tool support for spacecraft anomaly
resolution, prompting development of multi-purpose tools and knowledge
bases (see Wiegand et al. in the same session SM004), and educating
and engaging the next generation of space weather scientists.
Title: The Great "Non-Event" of 7 January 2014: Challenges in CME
Arrival Time and Geomagnetic Storm Strength Prediction
Authors: Mays, M. L.; Thompson, B. J.; Jian, L.; Evans, R. M.; Savani,
N.; Odstrcil, D.; Nieves-Chinchilla, T.; Richardson, I. G.
Bibcode: 2014AGUFMSH51E..04M
Altcode:
We present a case study of the 7 January 2014 event in order to
highlight current challenges in space weather forecasting of CME
arrival time and geomagnetic storm strength. On 7 January 2014 an X1.2
flare and CME with a radial speed ~2400 km/s was observed from active
region 11943. The flaring region was only ten degrees southwest of disk
center with extensive dimming south of the active region and preliminary
analysis indicated a fairly rapid arrival at Earth (~36 hours). Of the
eleven forecasting groups world-wide who participated in CCMC's Space
Weather Scoreboard (http://kauai.ccmc.gsfc.nasa.gov/SWScoreBoard),
nine predicted early arrivals and six predicted dramatic geomagnetic
storm impacts (Kp predictions ranged from 6 to 9). However, the CME
only had a glancing blow arrival at Earth - Kp did not rise above 3
and there was no geomagnetic storm. What happened? One idea is that
the large coronal hole to the northeast of the active region could
have deflected the CME. This coronal hole produced a high speed
stream near Earth reaching an uncommon speed of 900 km/s four days
after the observed CME arrival. However, no clear CME deflection was
observed in the outer coronagraph fields of view (~5-20Rs) where CME
measurements are derived to initiate models, therefore deflection seems
unlikely. Another idea is the effect of the CME flux rope orientation
with respect to Earth orbit. We show that using elliptical major and
minor axis widths obtained by GCS fitting for the initial CME parameters
in ENLIL would have improved the forecast to better reflect the observed
glancing blow in-situ signature. We also explore the WSA-ENLIL+Cone
simulations, the background solar wind solution, and compare with the
observed CME arrival at Venus (from Venus Express) and Earth.
Title: Brightenings Associated with Falling Filament Material
Authors: Gilbert, H. R.; Inglis, A. R.; Mays, M. L.; Ofman, L.;
Provornikova, E.; Thompson, B. J.; Young, C. A.
Bibcode: 2014AGUFMSH13B4101G
Altcode:
Solar filaments exhibit a range of eruptive-like dynamic activity,
including in some cases the confined or 'failed' ejection of prominence
material from the solar atmosphere. In rare cases material that
fails to erupt exhibits a strong interaction with the lower corona as
the material returns to the solar surface, observed as substantial
broadband brightening of EUV emission. We investigate a selection
of recent partial prominence eruptions in order to understand the
apparent rarity of the brightening phenomenon. Using combined data
from SDO/AIA and STEREO, we explore the energetics and kinematics of
these events, assessing the likely conditions of both the corona and
the prominence material that are required in order to explain these EUV
brightenings. We further demonstrate the potential of this phenomenon
as diagnostic tool for both prominence material conditions and the
coronal magnetic field.
Title: Forecasting the magnetic vectors within a CME at L1 by using
solar observations.
Authors: Savani, N.; Vourlidas, A.; Szabo, A.; Mays, M. L.; Evans,
R. M.; Thompson, B. J.; Richardson, I. G.; Pulkkinen, A. A.;
Nieves-Chinchilla, T.
Bibcode: 2014AGUFMSH43B4213S
Altcode:
The direction of magnetic vectors within coronal mass ejections has
important consequences to forecasting terrestrial behaviour, however
forecasting these vectors remains predominately elusive. Here,
we report that a simplified system is capable of replicating the
broad field rotations seen within flux rope CMEs at L1 monitors. The
predictions are performed under three main themes: 1) The majority of
the field rotations can be simplified to the constant-alpha force-free
(CAFF) flux model first implemented circa 1990. 2) The helicity will
follow the Bothmer & Schwenn system that relies on a reliable
helicity prediction of active regions during solar cycle. Which has
been recently confirmed by Wang [2013 ApJ]. 3) The majority of the
distortions, deflections and rotations will have already occurred
within coronagraphic field of view, thereby allowing the creation
of a projected "volume-of-influence" on the Sun, from which Earth's
position relative to the CME can be estimated. This presentation will
compare predicted results to the observations from 7 CME events and then
estimate the sources of uncertainty. As an example, the difference in
robust statistics from 2 solar cycles of CAFF model fittings for the
field magnitude will be compared to estimates generated from simulated
CME-sheaths within forecasting Enlil runs. The figure displays an
example field vector forecast from the techniques employed above.
Title: What Do EUV Dimmings Tell Us About CME Topology?
Authors: Thompson, B. J.; DeRosa, M. L.; Fisher, R. R.; Krista, L. D.;
Kwon, R. Y.; Mason, J. P.; Mays, M. L.; Nitta, N.; Savani, N.; West,
M. J.
Bibcode: 2014AGUFMSH43B4202T
Altcode:
Large-scale coronal EUV dimmings, developing on timescales of minutes
to hours in association with a flare or filament eruption, are known to
exhibit a high correlation with coronal mass ejections. However, it is
not clear why some CMEs have dimmings and some do not, nor is it clear
how these dimmings relate to CME topology. The inner coronal coverage
of SDO AIA and STEREO EUVI, combined with the extended field of view
of PROBA2's SWAP imager, allow us the opportunity to map the topology
of a dimming region in three dimensions into an erupting CME. Although
the location and extent of a dimming region appears to be the best
indicator of the inner "footprint" of a CME, the correlation is far
from perfect. However, dimmings can provide vital clues about the
development and 3D kinematics of a CME. This is particularly important
as we are entering an extended period of time where STEREO coronagraph
images will not always be available, and therefore the 3D properties of
a CME will be difficult to deduce. Therefore, understanding the inner
coronal manifestations of a CME can provide clues to its structure and
dynamics, even without multi-viewpoint coronagraph observations. We
present the results of this combined analysis effort, along with a
discussion of how dimmings can be used in forecasting CME directions.
Title: VizieR Online Data Catalog: WIYN open cluster
study. LXII. Photometry of M35 (Thompson+, 2014)
Authors: Thompson, B.; Frinchaboy, P.; Kinemuchi, K.; Sarajedini,
A.; Cohen, R.
Bibcode: 2014yCat..51480085T
Altcode:
Using the Kitt Peak National Observatory (KPNO) 0.9m MOSAIC camera,
a 59'*59' field of view has been observed in UBVRI. M35 images,
observed over two nights in 2000 February, were taken in two sequences:
short and long, allowing for the photometry of both the brightest
and faintest stars in the cluster. JHKs observations of M35 were
taken using the NEWFIRM instrument on the Kitt Peak 4m Telescope in
2008 February. The NEWFIRM camera is a grid of four 2k*2k IR detectors,
creating a 4k*4k image. (1 data file).
Title: WIYN Open Cluster Study. LXII. Comparison of Isochrone Systems
using Deep Multi-band Photometry of M35
Authors: Thompson, B.; Frinchaboy, P.; Kinemuchi, K.; Sarajedini,
A.; Cohen, R.
Bibcode: 2014AJ....148...85T
Altcode: 2014arXiv1408.1684T
The current generation of stellar isochrone models exhibits
non-negligible discrepancies due to variations in the input
physics. The success of each model is determined by how well it fits the
observations, and this paper aims to disentangle contributions from the
various physical inputs. New deep, wide-field optical and near-infrared
photometry (UBVRIJHKS ) of the cluster M35 is presented,
against which several isochrone systems are compared: Padova, PARSEC,
Dartmouth, and Y 2. Two different atmosphere models are
applied to each isochrone: ATLAS9 and BT-Settl. For any isochrone set
and atmosphere model, observed data are accurately reproduced for all
stars more massive than 0.7 M ⊙. For stars less massive
than 0.7 M ⊙, Padova and PARSEC isochrones consistently
produce higher temperatures than observed. Dartmouth and Y2
isochrones with BT-Settl atmospheres reproduce optical data accurately;
however, they appear too blue in IR colors. It is speculated that
molecular contributions to stellar spectra in the near-infrared may
not be fully explored, and that future study may reconcile these
differences.
Title: Evolving Solar Activity and Its Influence on Space and Earth
Authors: Pesnell, W. Dean; Thompson, Barbara
Bibcode: 2014esai.conf.....P
Altcode:
The 2014 Living with a Star (LWS) Science Meeting will focus on
advancing the understanding of the integral system coupling the Sun
to the Earth. An important part of this meeting is the inclusion of
the Hinode-8 and IRIS-2 meetings with complementary objectives towards
improved understanding of the evolving solar activity.
Title: Mechanisms and Observations of Coronal Dimming for the 2010
August 7 Event
Authors: Mason, James Paul; Woods, T. N.; Caspi, A.; Thompson, B. J.;
Hock, R. A.
Bibcode: 2014ApJ...789...61M
Altcode: 2014arXiv1404.1364M
Coronal dimming of extreme ultraviolet (EUV) emission has the
potential to be a useful forecaster of coronal mass ejections
(CMEs). As emitting material leaves the corona, a temporary void is
left behind which can be observed in spectral images and irradiance
measurements. The velocity and mass of the CMEs should impact the
character of those observations. However, other physical processes
can confuse the observations. We describe these processes and the
expected observational signature, with special emphasis placed on the
differences. We then apply this understanding to a coronal dimming
event with an associated CME that occurred on 2010 August 7. Data
from the Solar Dynamics Observatory's Atmospheric Imaging Assembly
and EUV Variability Experiment (EVE) are used for observations of the
dimming, while the Solar and Heliospheric Observatory's Large Angle
and Spectrometric Coronagraph and the Solar Terrestrial Relations
Observatory's COR1 and COR2 are used to obtain velocity and mass
estimates for the associated CME. We develop a technique for mitigating
temperature effects in coronal dimming from full-disk irradiance
measurements taken by EVE. We find that for this event, nearly 100%
of the dimming is due to mass loss in the corona.
Title: Predicting the magnetic vectors within coronal mass ejections
arriving at Earth
Authors: Savani, Neel P.; Vourlidas, Angelos; Szabo, Adam; Mays,
M. Leila; Thompson, Barbara; Richardson, Ian; Evans, Rebekah;
Pulkkinen, Antti; Nieves-Chinchilla, Teresa
Bibcode: 2014shin.confE.164S
Altcode:
The process by which the Sun affects the terrestrial environment
on short timescales is predominately driven by the amount
of magnetic reconnection between the solar wind and Earth's
magnetosphere. Reconnection occurs most efficiently when the solar
wind magnetic field has a southward component. The most severe impacts
are during the arrival of a coronal mass ejection (CME) when the
magnetosphere is both compressed and magnetically connected to the
heliospheric environment, leading to disruptions to, for example, power
grids and satellite navigation. Unfortunately, forecasting magnetic
vectors within coronal mass ejections remains elusive. Here we report
how, by combining a statistically robust helicity rule for a CME's solar
origin with a simplified flux rope topology the magnetic vectors within
the Earth-directed segment of a CME can be predicted. These magnetic
vectors can be incorporated into forecasting procedures to predict the
global response measured by the Kp index more reliably. In particular,
false predictions of strong geomagnetic events made without magnetic
field information are considerably reduced. As an example, the forecast
strength of a geomagnetic storm following a CME on 7 January 2014, is
reduced from G3 (strong) to G1 (minor) on the NOAA scale when magnetic
vectors are taken into account.
Title: What are the 'Correct' Parameters (Speed, Width, Direction)
of Coronal Mass Ejections Associated With 25 MeV Proton Events?
Authors: Richardson, Ian; Thompson, B. J.; von Rosenvinge, T. T.;
Cane, H. V.
Bibcode: 2014shin.confE.161R
Altcode:
A correlation between the intensity of solar energetic particle (SEP)
events and the speed of the associated coronal mass ejection (CME)
has been reported for over 35 years and is generally interpreted as
evidence for particle acceleration by CME-driven shocks. However,
the wide (orders of magnitude) spread in SEP intensity for events
related to CMEs with similar speeds has led to a number of efforts
to identify other influences on the size of SEP events. We suggest,
from comparing values from independent CME catalogs (e.g., CDAW,
CACTUS, DONKI, SEEDS) and from observations in quadrature for the
CMEs associated with 200 25 MeV proton events (Richardson et al.,
DOI 10.1007/s11207-014-0524-8), that uncertainties in CME speed also
contribute to this scatter. While CME speeds tend to be correlated in
different catalogs for the group of events, for individual events there
is no consistent relationship in the CME speeds. We point out several
ways this may occur, for example by different ways of defining CME speed
(e.g., the fastest feature or average over the CME front) and whether
CME identification and measurement is manual or automated. CME widths
vary even more widely between catalogs and are influenced by plane
of the sky projection and how the width is estimated from coronagraph
images. In particular, the high degree of association ( 50%) between
the SEP events and 'full halo' CMEs in the CDAW catalog is removed
when other catalogs or quadrature observations are considered. We
suggest that CME parameters should be carefully determined, and the
most reliable values used, when studying the relationship between SEP
intensity and CME parameters. We illustrate how a recently-developed
CME detection algorithm ('Time Convolution Mapping Method', TCMM,
Thompson and Young, 2014; http://sipwork.org/TCMM/) can provide improved
estimates of parameters of the CMEs associated with SEP events.
Title: Results from Persistence Mapping of Solar EUV Data
Authors: Thompson, Barbara J.; Young, C. Alex
Bibcode: 2014AAS...22421838T
Altcode:
Persistence Mapping is a simple image processing technique that is
useful for the visualization and depiction of gradually evolving
or intermittent structures. Persistence Mapping allows the user to
isolate extreme values in a data set, and is particularly useful for
the problem of capturing phenomena that are evolving in both space and
time. While integration or "time lapse" imaging uses the full sample
(of size N), Persistence Mapping rejects (N-1)/N of the data set and
identifies the most relevant 1/N values using the following rule:
if a pixel reaches an extreme value, it retains that value until
that value is exceeded. The simplest examples isolate minima and
maxima, and the technique has been used to extract the dynamics in
long-term evolution of comet tails, erupting material, spicules, and
EUV dimming regions. The presentation will review the technique and
discuss scientific results obtained through Persistence Mapping. For
more information, please see http://sipwork.org/persistence-mapping
Title: The Perihelion Passage of Comet ISON as seen by SDO
Authors: Pesnell, W. D.; Schrijver, C. J.; Boerner, P.; DeRosa, M. L.;
Liu, W.; Thompson, B. J.
Bibcode: 2013AGUFM.P24A..10P
Altcode:
Comet ISON will fly through perihelion on November 28, 2013. It is one
of the largest sungrazing comets to be seen in the Space Age. The Solar
Dynamics Observatory (SDO) has seen two previous sungrazing comets in
the extreme ultraviolet channels of the Atmospheric Imaging Assembly
(AIA). Comet ISON will fly farther from the Sun (perihelion distance
of 2.7 Rsun compared to 1.15 for Comet Lovejoy), meaning it probes
a different part of the solar corona, but its larger size should
provide enough mass to illuminate the path of the nucleus. Based on
the latest ephemeris, SDO will be able to track Comet ISON through
the entire perihelion passage by a series of off-point maneuvers. We
will present the AIA data obtained from the Comet ISON perihelion,
discussing the differences between Comets ISON and Lovejoy. We will
then summarize what we have learned from the observations and offer
some thoughts on what sungrazing comets may reveal about comets,
the Sun, and their interaction.
Title: Energy Release from Impacting Prominence Material Following
the 2011 June 7 Eruption
Authors: Gilbert, H. R.; Inglis, A. R.; Mays, M. L.; Ofman, L.;
Thompson, B. J.; Young, C. A.
Bibcode: 2013ApJ...776L..12G
Altcode: 2013arXiv1309.1769G
Solar filaments exhibit a range of eruptive-like dynamic activity,
ranging from the full or partial eruption of the filament mass
and surrounding magnetic structure as a coronal mass ejection to
a fully confined or failed eruption. On 2011 June 7, a dramatic
partial eruption of a filament was observed by multiple instruments
on board the Solar Dynamics Observatory (SDO) and Solar-Terrestrial
Relations Observatory. One of the interesting aspects of this event
is the response of the solar atmosphere as non-escaping material
falls inward under the influence of gravity. The impact sites show
clear evidence of brightening in the observed extreme ultraviolet
wavelengths due to energy release. Two plausible physical mechanisms
for explaining the brightening are considered: heating of the plasma due
to the kinetic energy of impacting material compressing the plasma, or
reconnection between the magnetic field of low-lying loops and the field
carried by the impacting material. By analyzing the emission of the
brightenings in several SDO/Atmospheric Imaging Assembly wavelengths,
and comparing the kinetic energy of the impacting material (7.6 ×
1026-5.8 × 1027 erg) to the radiative energy
(≈1.9 × 1025-2.5 × 1026 erg), we find
the dominant mechanism of energy release involved in the observed
brightening is plasma compression.
Title: Brightenings Caused by Falling Filament Material in the 2011
June 7 Event
Authors: Gilbert, Holly; Inglis, A.; Ofman, L.; Mays, L. M.; Thompson,
B. J.; Young, A.
Bibcode: 2013SPD....44...30G
Altcode:
Solar filaments exhibit a range of eruptive-like dynamic activity from
the full, or partial, eruption of the filament mass and surrounding
magnetic structure, as a CME, to a fully confined dynamic evolution or
‘failed’ eruption. On 2011 June 7, a dramatic partial eruption of a
filament was observed by multiple instruments and SDO and STEREO. One
of the interesting aspects of this partial eruption was the response
of the surface as non-erupting material fell back under the influence
of gravity. The impact sites show clear evidence of brightening in the
observed EUV wavelengths due to energy release by the impact. There
are two plausible physical mechanisms of the brightening: heating
of the plasma due to the kinetic energy of the impacting material -
compression of the plasma, or reconnection between the magnetic field of
the low-laying loops with the field carried by the impacting material,
or combination thereof. By analyzing the emission of the brightenings
in several SDO/AIA wavelength, and comparing the kinetic energy of the
impacting material (with true velocity determined from triangulation
of the two STEREO spacecraft) to the radiative energy we provide clues
for the dominant mechanism of energy release involved in the observed
brightenings.
Title: The ISS Space Plasma Laboratory: A Proposed Orbital Solar
Physics Simulation Lab
Authors: Antiochos, Spiro K.; DeVore, C. R.; Thompson, B. J.; Bering,
E. A., III; Edeen, G.; Carter, M.; Giambusso, M.; Olsen, C. S.;
Squire, J.; Larson, D.; McFadden, J. P.; Longmier, B.
Bibcode: 2013shin.confE.162A
Altcode:
We describe a proposed laboratory-experiment research program that will
answer several fundamental questions concerning the dynamical opening
and closing of the Sun's magnetic field - the defining property of
CMEs and eruptive flares. Our experiment is specifically designed to
address the key questions of the rate of reconnection in the topology of
a flare or heliospheric current sheet, its burstiness, and the energy
partition between thermal, kinetic, and particle. Of course, it seems
completely contradictory to use a laboratory experiment to study an open
magnetic system, because so far all laboratory plasmas have very solid
walls. The pioneering feature of our program is that the experiments
will be performed on the International Space Station (ISS). Only by
going into space can we obtain the open domain that is absolutely
essential for studying the opening and closing of coronal flux. Our
research program will provide the instrumentation infrastructure,
modeling and solar data expertise and initial scientific understanding
required to develop the VASIMR® VF-200 high powered plasma source
into a wall-less, orbiting ISS Space Plasma Laboratory (ISPL) national
facility. For example, the VF-200 exhaust will simulate conditions
in the solar corona during CMEs/eruptive flares by creating plasma
jets in open magnetic field geometries. Such a facility would measure
quantities in the plasma flow with the goal of measuring magnetic
reconnection and transport phenomena that should be similar in nature
to those occurring in the corona and solar wind. Our experiment will
capture all the effects inherent in a fully 3D magnetic system and
reproduce some of the physics occurring in the post initiation phase
of CMEs/eruptive flares. The Aurora Plasma Diagnostics Package (APDP)
will carry Langmuir probes, a retarding potential analyzer (RPA),
dc magnetometer, plasma wave detectors, Faraday cups, electrostatic
analyzers, solid state energetic particle telescope and Ar II and
broadband imagers.
Title: Brightenings Caused by Falling Filament Material in the 2011
June 7 Event
Authors: Gilbert, Holly; Inglis, Andrew; Mays, Leila; Ofman, Leon;
Thompson, Barbara; Young, Alex
Bibcode: 2013shin.confE..74G
Altcode:
Solar filaments exhibit a range of eruptive-like dynamic activity,
ranging from the full or partial eruption of the filament mass and
surrounding magnetic structure as a coronal mass ejection (CME), to
a fully confined dynamic evolution or 'failed' eruption. On 2011 June
7, a dramatic partial eruption of a filament was observed by multiple
instruments on SDO and STEREO. One of the interesting aspects of this
partial eruption is the response of the solar atmosphere as non-escaping
material falls inward under the influence of gravity. The impact sites
show clear evidence of brightening in the observed EUV wavelengths due
to energy release. Two plausible physical mechanisms explaining the
brightening are considered: heating of the plasma due to the kinetic
energy of impacting material compressing the plasma, or reconnection
between the magnetic field of the low-lying loops and the field carried
by the impacting material. By analyzing the emission of the brightenings
in several SDO/AIA wavelengths, and comparing the kinetic energy of the
impacting material ((2.12-60.4) - 10^26 ergs) to the radiative energy
( 10^25 ergs) we find the dominant mechanism of energy release involved
in the observed brightening is plasma compression.
Title: Exploring the Network of SDO Science
Authors: Pesnell, W. Dean; Thompson, Barbara
Bibcode: 2013enss.conf.....P
Altcode:
Living With a Star's Solar Dynamics Observatory invites you to its
2013 Science Workshop to be held March 3-8, 2013 at the Hyatt Regency
Chesapeake Bay in Cambridge, MD (http://chesapeakebay.hyatt.com/). The
workshop is a follow-on to the "Many Spectra of Solar Activity" workshop
held May 1-5, 2011 in Squaw Valley, CA. Scientific sessions will
feature a broad spectrum of science topics fundamental to SDO's science
investigations: Atmospheric Imaging Assembly (AIA), EUV Variability
Experiment (EVE), and Helioseismic and Magnetic Imager (HMI), as well
as the overlap between SDO and other scientific missions and activities.
Title: Understanding Solar Eruptive Events
Authors: Mason, James P.; Hock, Rachel A.; Woods, Thomas N.; Thompson,
Barbara J.; Webb, David F.; Caspi, Amir
Bibcode: 2013enss.confE.138M
Altcode:
Coronal dimming is studied using data from the EUV Variability
Experiment (EVE) and the Atmospheric Imaging Assembly (AIA), both
onboard the Solar Dynamics Observatory (SDO). Dimming can be caused
by a number of physical processes, including mass loss (e.g. coronal
mass ejections), obscuration of bright features (e.g. flaring loops)
by dark features (e.g. filament eruptions), global scale waves, and
changes of temperature in the emitting plasma. Each of these processes
have unique spectral signatures, which EVE and AIA are well suited
to observe. We are building a method for isolating the signature
indicative of mass loss, which is thought to be correlated with the
kinetics of coronal mass ejections. Our analysis of the M9 flare on
August 4, 2011 are shown as an example of all four of these physical
processes and their spectral signatures.
Title: STEREO Observations of Fast Magnetosonic Waves in the Extended
Solar Corona Associated with EIT/EUV Waves
Authors: Kwon, Ryun-Young; Ofman, Leon; Olmedo, Oscar; Kramar, Maxim;
Davila, Joseph M.; Thompson, Barbara J.; Cho, Kyung-Suk
Bibcode: 2013ApJ...766...55K
Altcode:
We report white-light observations of a fast magnetosonic wave
associated with a coronal mass ejection observed by STEREO/SECCHI/COR1
inner coronagraphs on 2011 August 4. The wave front is observed in the
form of density compression passing through various coronal regions such
as quiet/active corona, coronal holes, and streamers. Together with
measured electron densities determined with STEREO COR1 and Extreme
UltraViolet Imager (EUVI) data, we use our kinematic measurements of
the wave front to calculate coronal magnetic fields and find that the
measured speeds are consistent with characteristic fast magnetosonic
speeds in the corona. In addition, the wave front turns out to be
the upper coronal counterpart of the EIT wave observed by STEREO
EUVI traveling against the solar coronal disk; moreover, stationary
fronts of the EIT wave are found to be located at the footpoints of
deflected streamers and boundaries of coronal holes, after the wave
front in the upper solar corona passes through open magnetic field
lines in the streamers. Our findings suggest that the observed EIT
wave should be in fact a fast magnetosonic shock/wave traveling in
the inhomogeneous solar corona, as part of the fast magnetosonic wave
propagating in the extended solar corona.
Title: Investigating Coronal Activity by Release Using Sublimation
Authors: Moore, T. E.; Bryans, P.; Pesnell, W. D.; Thompson, B. J.
Bibcode: 2012AGUFMSH21D..05M
Altcode:
Plasma tails left by sun-grazing comets are visible in EUV, expanding
their traditional role as "windsocks" into the low corona and serving
as natural "chemical release" experiments. SDO obtained spectrally
resolved video imagery of passages as close as 0.15 Rs to the solar
photosphere at 12 sec frame cadence. Vaporized cometary materials
form sublimation trails or "subtrails" that persist as long as 20
min. in 13.1 and 17.1 nm channels. Striation along local magnetic flux
tubes implies filamentation of the visible plasma, and the subtrails
exhibit substantial deviations from the comet orbital track. These
reveal coronal winds and shears with velocities that are comparable to
the comet velocity of up to 600 km/s. We analyze the likely origins
and directionality of these winds and their implications for coronal
heating in the altitude range where ion-neutral collision mean free
paths are longer than the gyro radius but shorter than the atmospheric
scale height, that is, the solar transition region. With active impact
or photo-ionization, and charge exchange, the inferred super-thermal,
sub-Alfvenic ion-neutral relative velocities will lead to ion pick-up
distributions that decay or relax into "kappa" distributions with
super-thermal power law tails that are relevant to the formation of
the corona.
Title: EUV Dimmings: Formation Mechanisms and Associated Phenomena
Authors: Thompson, B. J.; Mays, M. L.; West, M. J.
Bibcode: 2012AGUFMSH44A..03T
Altcode:
Large-scale coronal EUV dimmings, developing on timescales of minutes
to hours in association with a flare or filament eruption, are known
to exhibit a high correlation with coronal mass ejections. While most
observations indicate that the decrease in emission in a dimming is due,
at least in part, to a density decrease, a complete understanding
requires us to examine at least four mechanisms that have been
observed to cause darkened regions in the corona: 1) mass loss, 2)
cooling, 3) heating, and 4) absorption/obscuration. Recent advances in
automatic detection, observations with improved cadence and resolution,
multi-viewpoint imaging, and spectroscopic studies have continued to
shed light on dimming formation, evolution, and recovery. However,
there are still some outstanding questions, including 1) Why do some
CMEs show dimming and some do not? 2) What determines the location of
a dimming? 3) What determines the temporal evolution of a dimming? 4)
How does the post-eruption dimming connect to the ICME? 5) What is the
relationship between dimmings and other CME-associated phenomena? The
talk will emphasize the different formation mechanisms of dimmings
and their relationship to CMEs and CME-associated phenomena.
Title: Erratum: "SDO/AIA Observation of Kelvin-Helmholtz Instability
in the Solar Corona" (2011, ApJ,
734, L11)
Authors: Ofman, L.; Thompson, B. J.
Bibcode: 2012ApJ...760L..19O
Altcode:
No abstract at ADS
Title: Vibrational Shift of Adsorbed Carbon Dioxide Within a
Metal-Organic Framework
Authors: Fitzgerald, S.; Pierce, C.; Schloss, J.; Thompson, B.;
Rowsell, J.
Bibcode: 2012mss..confEMJ11F
Altcode:
There is much interest in a class of materials known as Metal-Organic
Frameworks (MOFs). While practical applications center on hydrogen
storage and carbon sequestration, these highly porous, crystalline
materials also provide an excellent opportunity for performing matrix
isolation experiments. In this talk we will present data on MOF-74,
a honey-comb structure consisting of metal-oxide units linked by
aromatic rings. Infrared spectra show that for a series of different
metal cations, Mn2+, Fe2+, Co2+,
Ni2+, and Zn2+ the vibrational modes of adsorbed
CO2 are all red shifted relative to the gas phase values. In
contrast the ν3 mode of CO2 adsorbed within
the Mg version of MOF-74 is unique in showing a blue shift. It is
accompanied by broader sidebands associated with librational or center
of mass motion of the adsorbed CO2. Spectra obtained below
100 K show the emergence of a second ν3 band indicating a
further distortion of the CO2 molecule. These results will
be discussed in terms of the interaction mechanisms of the different
metal cations and in particular the fact that the Mg version of MOF-74
has a very strong affinity for CO2 with a binding enenergy
of 47 kJ/mol, more than 5 kJ/mol greater than any other MOF.
Title: Comparison of Prominence Structures with Instances of Flux
Rope CMEs in STEREO Data
Authors: Rager, Amy; Thompson, B. J.; Antiochos, S. K.; Thernisien,
A.; Thompson, W. T.
Bibcode: 2012AAS...22020004R
Altcode:
STEREO A and B CME data have been visually searched for instances
of flux ropes, signified by a concave outward cavity feature in
the COR1 coronagraph. The flux rope events selected were observed
by both spacecraft, and also had visible prominences in both EUVI-A
and EUVI-B. The appearance of a flux rope was compared to the angle
of the inferred magnetic neutral line of the CME to discover if a
relationship existed. The GCS CME flux rope model was fit to the COR1
data, allowing for a clearer representation of the flux rope structure
to compare with the magnetic neutral line.
Title: Modeling waves, flows, and instabilities produced by impulsive
events in coronal active regions
Authors: Ofman, L.; Liu, W.; Wang, T. J.; Davila, J. M.; Thompson,
B. J.
Bibcode: 2012decs.confE..73O
Altcode:
Recent high-resolution observations by SDO/AIA combined with spectral
data from Hinode provide insights into the properties of MHD waves,
flows, and instabilities in coronal active region plasma and
their connection with impulsive energy release. Shear flow driven
instabilities, such as the Kelvin-Helmholtz (KH) instability were
only recently detected in detail in the corona. I will present recent
results of 3D MHD models of slow and fast magnetosonic waves in active
regions excited by jets and quasi-periodic flows driven by micro-flares
at loops' footpoints. I will discuss models of super-fast magnetosonic
waves detected recently by SDO/AIA. I will also discuss models of global
(EIT) waves, and KH instabilities driven by CMEs. The relations between
waves, flows, instabilities, and impulsive events such as flares and
CMEs are becoming apparent thanks to the combination of observational
data analysis and the 3D MHD modeling. Understanding these relations
is useful for coronal seismology and for tracing the flow of energy
from the transition region to the corona.
Title: The Solar Dynamics Observatory (SDO)
Authors: Pesnell, W. Dean; Thompson, B. J.; Chamberlin, P. C.
Bibcode: 2012SoPh..275....3P
Altcode:
The Solar Dynamics Observatory (SDO) was launched on 11 February 2010 at
15:23 UT from Kennedy Space Center aboard an Atlas V 401 (AV-021) launch
vehicle. A series of apogee-motor firings lifted SDO from an initial
geosynchronous transfer orbit into a circular geosynchronous orbit
inclined by 28° about the longitude of the SDO-dedicated ground station
in New Mexico. SDO began returning science data on 1 May 2010. SDO
is the first space-weather mission in NASA's Living With a Star (LWS)
Program. SDO's main goal is to understand, driving toward a predictive
capability, those solar variations that influence life on Earth and
humanity's technological systems. The SDO science investigations will
determine how the Sun's magnetic field is generated and structured,
how this stored magnetic energy is released into the heliosphere and
geospace as the solar wind, energetic particles, and variations in the
solar irradiance. Insights gained from SDO investigations will also
lead to an increased understanding of the role that solar variability
plays in changes in Earth's atmospheric chemistry and climate. The
SDO mission includes three scientific investigations (the Atmospheric
Imaging Assembly (AIA), Extreme Ultraviolet Variability Experiment
(EVE), and Helioseismic and Magnetic Imager (HMI)), a spacecraft bus,
and a dedicated ground station to handle the telemetry. The Goddard
Space Flight Center built and will operate the spacecraft during
its planned five-year mission life; this includes: commanding the
spacecraft, receiving the science data, and forwarding that data to the
science teams. The science investigations teams at Stanford University,
Lockheed Martin Solar Astrophysics Laboratory (LMSAL), and University
of Colorado Laboratory for Atmospheric and Space Physics (LASP) will
process, analyze, distribute, and archive the science data. We will
describe the building of SDO and the science that it will provide
to NASA.
Title: The Sun-Earth Connection near Solar Minimum: Placing it
into Context
Authors: Bisi, Mario M.; Thompson, Barbara J.; Emery, Barbara A.;
Gibson, Sarah E.; Leibacher, John; van Driel-Gesztelyi, Lidia
Bibcode: 2011SoPh..274....1B
Altcode:
No abstract at ADS
Title: A Snapshot of the Sun Near Solar Minimum: The Whole Heliosphere
Interval
Authors: Thompson, Barbara J.; Gibson, Sarah E.; Schroeder, Peter C.;
Webb, David F.; Arge, Charles N.; Bisi, Mario M.; de Toma, Giuliana;
Emery, Barbara A.; Galvin, Antoinette B.; Haber, Deborah A.; Jackson,
Bernard V.; Jensen, Elizabeth A.; Leamon, Robert J.; Lei, Jiuhou;
Manoharan, Periasamy K.; Mays, M. Leila; McIntosh, Patrick S.; Petrie,
Gordon J. D.; Plunkett, Simon P.; Qian, Liying; Riley, Peter; Suess,
Steven T.; Tokumaru, Munetoshi; Welsch, Brian T.; Woods, Thomas N.
Bibcode: 2011SoPh..274...29T
Altcode: 2011SoPh..tmp..413T
We present an overview of the data and models collected for the
Whole Heliosphere Interval, an international campaign to study the
three-dimensional solar-heliospheric-planetary connected system near
solar minimum. The data and models correspond to solar Carrington
Rotation 2068 (20 March - 16 April 2008) extending from below the
solar photosphere, through interplanetary space, and down to Earth's
mesosphere. Nearly 200 people participated in aspects of WHI studies,
analyzing and interpreting data from nearly 100 instruments and
models in order to elucidate the physics of fundamental heliophysical
processes. The solar and inner heliospheric data showed structure
consistent with the declining phase of the solar cycle. A closely
spaced cluster of low-latitude active regions was responsible for an
increased level of magnetic activity, while a highly warped current
sheet dominated heliospheric structure. The geospace data revealed an
unusually high level of activity, driven primarily by the periodic
impingement of high-speed streams. The WHI studies traced the solar
activity and structure into the heliosphere and geospace, and provided
new insight into the nature of the interconnected heliophysical system
near solar minimum.
Title: The Whole Heliosphere Interval in the Context of a Long and
Structured Solar Minimum: An Overview from Sun to Earth
Authors: Gibson, S. E.; de Toma, G.; Emery, B.; Riley, P.; Zhao, L.;
Elsworth, Y.; Leamon, R. J.; Lei, J.; McIntosh, S.; Mewaldt, R. A.;
Thompson, B. J.; Webb, D.
Bibcode: 2011SoPh..274....5G
Altcode: 2011SoPh..tmp..427G
Throughout months of extremely low solar activity during the recent
extended solar-cycle minimum, structural evolution continued to be
observed from the Sun through the solar wind and to the Earth. In
2008, the presence of long-lived and large low-latitude coronal holes
meant that geospace was periodically impacted by high-speed streams,
even though solar irradiance, activity, and interplanetary magnetic
fields had reached levels as low as, or lower than, observed in past
minima. This time period, which includes the first Whole Heliosphere
Interval (WHI 1: Carrington Rotation (CR) 2068), illustrates the
effects of fast solar-wind streams on the Earth in an otherwise quiet
heliosphere. By the end of 2008, sunspots and solar irradiance had
reached their lowest levels for this minimum (e.g., WHI 2: CR 2078),
and continued solar magnetic-flux evolution had led to a flattening
of the heliospheric current sheet and the decay of the low-latitude
coronal holes and associated Earth-intersecting high-speed solar-wind
streams. As the new solar cycle slowly began, solar-wind and geospace
observables stayed low or continued to decline, reaching very low
levels by June - July 2009. At this point (e.g., WHI 3: CR 2085) the
Sun-Earth system, taken as a whole, was at its quietest. In this article
we present an overview of observations that span the period 2008 -
2009, with highlighted discussion of CRs 2068, 2078, and 2085. We show
side-by-side observables from the Sun's interior through its surface and
atmosphere, through the solar wind and heliosphere and to the Earth's
space environment and upper atmosphere, and reference detailed studies
of these various regimes within this topical issue and elsewhere.
Title: Solar Dynamics and Magnetism from the Interior to the
Atmosphere
Authors: Pesnell, W. Dean; Thompson, Barbara
Bibcode: 2011sdmi.conf.....P
Altcode:
The goal of the workshop is to discuss recent advances and new problems
in the exploration of the Sun's interior structure, solar dynamics and
dynamo, mechanisms of sunspot and active regions formation, sources of
solar irradiance variations, and links between the subsurface dynamics,
flaring and CME activity. NASA's Solar Dynamics Observatory (SDO)
mission is providing a large amount of new data on solar dynamics and
magnetic activities during the rising phase of the current and highly
unusual solar cycle. These data are complemented by the continuing
SOHO mission, and by ground-based observatories that include the GONG
helioseismology network and the New Solar Telescope. This unprecedented
amount of data provides a unique opportunity for multi-instrument
investigations that address fundamental problems of the origin of
solar magnetic activity at various spatial and temporal scales. The data is being used to develop new methods for forecasting
solar cycles, emergence and evolution of active regions and their
flaring and CME activity. The scientific program will begin
on Monday, October 31 at 9 AM, and conclude on Friday, November
4 at 1PM. Abstracts are solicited on the following topics: -
"Local and Global Helioseismology" - "Large-Scale Dynamics, Magnetism
and Dynamo" - "Emerging Magnetic Flux and Subsurface Dynamics" -
"Formation, Structure and Evolution of Sunspots and Active Regions" -
"Numerical Simulations and Laboratory Experiments" - "Observations of
the Solar Dynamics and Magnetism" - "Links between the Solar Interior
and Atmosphere" - "Sources of Spectral and Total Irradiance Variations"
- "Dynamics and Magnetic Topology of Flares and CMEs" The workshop
program will include invited and contributed talks, as well as poster
sessions. On the last day, 4 splinter working group meetings will be
organized: 1. Helioseismology (organizers R. Bogart, R. Komm,
A. Kosovichev) 2. Vector Magnetometry (organizer T. Hoeksema and
A. Pevtsov) 3. Feature Recognition, and Data Distribution and Access
(organizers P. Martens and N. Hurlburt) 4. Numerical Simulations and
Modeling (organizers N. Mansour and I. Kitiashvili)
Title: SDO/AIA Observation of Kelvin-Helmholtz Instability in the
Solar Corona
Authors: Ofman, L.; Thompson, B. J.
Bibcode: 2011ApJ...734L..11O
Altcode: 2011arXiv1101.4249O
We present observations of the formation, propagation, and decay of
vortex-shaped features in coronal images from the Solar Dynamics
Observatory associated with an eruption starting at about 2:30
UT on 2010 April 8. The series of vortices were formed along the
interface between an erupting (dimming) region and the surrounding
corona. They ranged in size from several to 10 arcsec and traveled
along the interface at 6-14 km s-1. The features were
clearly visible in six out of the seven different EUV wave bands of
the Atmospheric Imaging Assembly. Based on the structure, formation,
propagation, and decay of these features, we identified the event as
the first observation of the Kelvin-Helmholtz instability (KHI) in the
corona in EUV. The interpretation is supported by linear analysis and
by a nonlinear 2.5-dimensional magnetohydrodynamic model of KHI. We
conclude that the instability is driven by the velocity shear between
the erupting and closed magnetic field of the coronal mass ejection. The
shear-flow-driven instability can play an important role in energy
transfer processes in coronal plasma.
Title: Molecular Hydrogen Interactions Within Metal-Organic Frameworks
Authors: Fitzgerald, S.; Pierce, C.; Schloss, J.; Thompson, B.;
Rowsell, J.
Bibcode: 2011mss..confEMJ10F
Altcode:
There is much interest in understanding the details of molecular
hydrogen physisorption within highly porous materials that could be
used for hydrogen storage applications. Unfortunately, the structures of
the most promising materials are too complex for ab inito calculations
and DFT models are notoriously unreliable for weak interactions. A new
approach based on so-called van der Waals DFT has been proposed for
explaining the behavior of molecular hydrogen within metal-organic
frameworks.1 In this talk we will present IR spectra of
adsorbed hydrogen within a series of isostructural MOFs containing
Mg2+ and various first-row transition metal cations. The
data clearly show that H2 binds first at an open metal
site, with a large vibrational redshift that correlates with the
magnitude of the site binding energy. These spectra show minimal
effects due to H2\cdot\cdotCdotH2 interactions
and are significantly different from the recent findings of the Chabal
group.1 After collecting spectra over a wide range of
temperature and H2 pressure, we could only reproduce their
experimental observations by exposing samples to moist air, which is
well-known to cause occupation of the open metal sites by water. This
calls into question the appropriateness of the van der Waals DFT
models that were used to support their interpretations.1
We are hopeful that the spectra we present will inspire improved
parametrization of such advanced computational models, or prompt the
development of superior ones. 1. Nijjem et al., J. Am. Chem. Soc. 132,
14834 (2010).
Title: Pulsed Flows Along a Cusp Structure Observed with SDO/AIA
Authors: Thompson, Barbara; Démoulin, P.; Mandrini, C.; Mays, M.;
Ofman, L.; Van Driel-Gesztelyi, L.; Viall, N.
Bibcode: 2011SPD....42.2117T
Altcode: 2011BAAS..43S.2117T
We present observations of a cusp-shaped structure that formed after
a flare and coronal mass ejection on 14 February 2011. Throughout
the evolution of the cusp structure, blob features up to a few Mm in
size were observed flowing along the legs and stalk of the cusp at
projected speeds ranging from 50 to 150 km/sec. Around two dozen blob
features, on order of 1 - 3 minutes apart, were tracked in multiple
AIA EUV wavelengths. The blobs flowed outward (away from the Sun)
along the cusp stalk, and most of the observed speeds were either
constant or decelerating. We attempt to reconstruct the 3-D magnetic
field of the evolving structure, discuss the possible drivers of the
flows (including pulsed reconnection and tearing mode instability),
and compare the observations to studies of pulsed reconnection and
blob flows in the solar wind and the Earth's magnetosphere.
Title: Accessing SDO Data : The Poster
Authors: Hourcle, Joseph; Addison, K.; Bogart, R.; Chamberlin, P.;
Freeland, S.; Hughitt, V. K.; Ireland, J.; Maddox, M.; Mueller, D.;
Somani, A.; Sommers, J.; Thompson, B.; solar physics data community,
The
Bibcode: 2011SPD....42.2130H
Altcode: 2011BAAS..43S.2130H
As the data from SDO are useful for a variety of purposes, including
solar physics, helioseismology, atmospheric science, space weather
forecasting, education and public outreach, a wide variety of tools
have been development to cater to the different needs of the various
groups. Systems have been developed for pipeline processing, searching,
browsing, subsetting, or simply just moving around large volumes
of data. We present a quick overview of the different systems
that can be used to access SDO data including (J)Helioviewer, the
Heliophysics Event Knowledgebase (HEK), the Virtual Solar Observatory
(VSO), the Integrated Space Weather Analysis System (iSWA), the
Data Record Management System (DRMS), and various websites. We cover
web-based applications, application programming interfaces (APIs),
and IDL command line tools. This poster serves as a supplement
to the oral presentation as a place to distribute information about
the various interfaces and to collect feedback about any unmet needs
for data access.
Title: The International Space Weather Initiative (ISWI)
Authors: Davila, Joseph M.; Gopalswamy, Nat; Thompson, Barbara J.;
Bogdan, Tom; Hapgood, Mike
Bibcode: 2011sswh.book..375D
Altcode:
No abstract at ADS
Title: SDO/AIA Observation of Kelvin-Helmholtz Instability in the
Solar Corona associated with CME
Authors: Ofman, L.; Thompson, B. J.
Bibcode: 2010AGUFMSH14A..02O
Altcode:
We present observations of the formation, propagation and decay
of vortex-shaped features in coronal images from the Solar Dynamics
Observatory (SDO) associated with Coronal Mass Ejection (CME) at about
2:34UT on Apr 8, 2010. The series of vortices are seen at 3:20UT
to 3:37UT formed along the interface between erupting (dimming)
region and the surrounding corona and ranged in size from several
to ten arcseconds, traveling along the interface at approximately
5 km/sec. The features are clearly visible in five out of the six
different EUV wavebands of the Atmospheric Imaging Assembly (AIA). Based
on the structure, formation, propagation and decay of these features, we
conclude that these are the first observations of the Kelvin-Helmholtz
(KH) instability in the corona. The KH instability is likely driven
by the velocity shear between the erupting and closed magnetic field
regions. We compare the dynamics and structure of SDO/AIA observation
to an MHD model of KH instability in the nonlinear stage in magnetized
plasma, and find good agreement.
Title: The Many Ways to Access SDO Data
Authors: Thompson, B. J.; Hourcle, J. A.; Addison, K.; Bogart, R. S.;
Chamberlin, P. C.; Dietert, H.; Freeland, S. L.; Hughitt, V. K.;
Ireland, J.; Mueller, D.; Somani, A.; Sommers, J.
Bibcode: 2010AGUFMSH23C1865T
Altcode:
To solve the issue of dealing with the large volume of data available
from AIA, there are a number of ways to get access to SDO data. With
Helioviewer, the Heliophysics Event Knowledgebase, the Virtual Solar
Observatory, and the PI-provided tools, scientists and other interested
parties have a number of ways to find and obtain data of interest. We
present an overview of the differences between the various systems,
and a flow chart to help determine which one might be of the most
benefit for a given situation.
Title: Observed Core of a Gradual Solar Energetic Particle Event
Authors: Kocharov, L.; Reiner, M. J.; Klassen, A.; Thompson, B. J.;
Valtonen, E.
Bibcode: 2010ApJ...725.2262K
Altcode:
Using space-borne particle and EUV detection and radio spectrograms
from both ground-based and space-borne instruments, we study the first
phase of the major solar energetic particle (SEP) event associated with
the western solar flare and fast and wide coronal mass ejection (CME) on
2000 April 4. The SEP event being observed at the magnetic connection to
the eruption's center starts with deka-MeV nucl-1 helium- and
relativistic electron-rich production from coronal sources identified
with the electromagnetic diagnostics and the SEP event modeling. The
broadband observations and modeling of the initial phase of the
"well-connected" major SEP event support the idea that acceleration
of SEPs starts in the helium-rich plasma of the eruption's core in
association with coronal shocks and magnetic reconnections caused by the
CME liftoff, and that the coronal component dominates during the first
hour of the SEP event considered, not yet being shielded by the CME bow
shock in the solar wind. The first phase of the SEP event is followed
by a second phase of SEP production associated with a decelerating
CME-driven shock wave in the solar wind, which accelerates ions from
a distinct, helium-poor seed particle population that may originate
from the CME interaction with a coronal streamer.
Title: a Three-Dimensional View of Major Solar Energetic Particle
Events
Authors: Kocharov, L. G.; Valtonen, E.; Thompson, B. J.; Reiner,
M. J.; Klassen, A.
Bibcode: 2010AGUFMSH42B..04K
Altcode:
Using SOHO particle and EUV detection and radio spectrograms from both
ground-based and spaceborne instruments, we study the first phase
of two major solar energetic particle (SEP) events associated with
solar eruptions centered at different solar longitudes. A major solar
energetic particle (SEP) event observed on 4 April 2000 was associated
with western solar flare and fast and wide coronal mass ejection
(CME). The SEP event near the eruption's center starts with deka-MeV/n
helium- and relativistic electron- rich production from coronal sources
identified with the electromagnetic diagnostics. Observations of the
initial phase of the "well-connected" major SEP event support the
idea that acceleration of SEPs starts in the helium-rich plasma of
the eruption's core well behind the CME leading edge, in association
with coronal shocks and/or magnetic reconnection caused by the CME
liftoff; and those "coronal" components dominate during the first ~1.5
hour of the SEP event, not yet being hidden by the CME-bow shock in
solar wind. The 12 September 2000 eruption's center was angle-distant
with respect to the SOHO-connected heliolongitude. The event began
with a first-phase, hard-spectrum SEP production that was extremely
poor in helium, and onset of the first stage of the SEP event as
observed on SOHO was delayed by an extra half hour, compared to the
"well-connected" event of 4 April 2000. At magnetic connection to
the eruption's periphery, onset of SEP emission is delayed for a
time of the lateral expansion that is visualized by global coronal
(EIT) waves. In both cases, the initial, coronal phase of SEP event
is followed by the second-phase SEP production associated with a
decelerating CME-driven shock wave in solar wind, which accelerates
deka-MeV/n ions from a helium-poor particle population for ~6--12 hours,
until the interplanetary shock slows down to below 1000 km/s. Based
on these and other SOHO observations, we discuss what findings we can
expect from STEREO in the SOHO era perspective.
Title: Escape of O+ through the distant tail plasma sheet
Authors: Kistler, L. M.; Galvin, A. B.; Popecki, M. A.; Simunac,
K. D. C.; Farrugia, C.; Moebius, E.; Lee, M. A.; Blush, L. M.;
Bochsler, P.; Wurz, P.; Klecker, B.; Wimmer-Schweingruber, R. F.;
Opitz, A.; Sauvaud, J. -A.; Thompson, B.; Russell, C. T.
Bibcode: 2010GeoRL..3721101K
Altcode:
In February 2007, the STEREO-B spacecraft encountered the
magnetosheath, plasma sheet and plasma sheet boundary layer from
about 200 RE to 300 RE downtail. This time
period was during solar minimum, and there was no storm activity
during this month. Using data from the PLASTIC instrument, we find
that even during quiet times, O+ is a constant feature of
the deep magnetotail, with an O+ density of about 15% of
the O+ density in the near-earth plasma sheet for similar
conditions. The tailward flux of the O+ is similar to the
flux of O+ beams that have been observed in the lobe/mantle
region of the deep tail. The total outflow rate of the O+
down the plasma sheet is 1.1 × 1024 ions/s, which is 10%
of the total outflow rate of 1 × 1025 ions/s, and of the
same order as the estimated loss from dayside transport.
Title: Whole Heliosphere Interval: Overview of JD16
Authors: Webb, David F.; Gibson, Sarah E.; Thompson, Barbara J.
Bibcode: 2010HiA....15..471W
Altcode:
The Whole Heliosphere Interval is an international observing and
modeling effort to characterize the three-dimensional interconnected
solar-heliospheric-planetary system, i.e., the “heliophysical”
system. WHI was part of the International Heliophysical Year, on the
50th anniversary of the International Geophysical Year, and benefited
from hundreds of observatories and instruments participating in IHY
activities. WHI describes the 3-D heliosphere originating from solar
Carrington Rotation 2068, March 20-April 16, 2008. The focus of IAU JD16
was on analyses of observations obtained during WHI, and simulations
and modeling involving those data and that period. Consideration of
the WHI interval in the context of surrounding solar rotations and/or
compared to last solar minimum was also encouraged. Our goal was to
identify connections and commonalities between the various regions of
the heliosphere.
Title: The Whole Heliosphere Interval in the Context of the Current
Solar Minimum
Authors: Gibson, S. E.; Webb, D. F.; Thompson, B. J.
Bibcode: 2010ASPC..428..223G
Altcode:
The current solar minimum may not be "peculiar" when considered on
scales of a century or more. However, the opportunity for discovery
yielded by its extended nature, in combination with the abundance of
modern observations, cannot be overstated. In this paper, we describe
the Whole Heliosphere Interval (WHI), an in-depth study of the Sun-Earth
system for a solar rotation in March/April 2008. We discuss how WHI
fits within the broader context of the current deep, long, and complex
solar minimum.
Title: Molecular Hydrogen Adsorption in Metal-Organic Frameworks
Authors: Fitzgerald, S.; Friedman, M.; Gotdank, J.; Thompson, B.;
Rowsell, J.
Bibcode: 2010mss..confEFB01F
Altcode:
There is presently much interest in studying hydrogen storage materials
for fuel cell applications. A promising class of physisorbents for
this purpose is metal-organic frameworks, which consist of metal ions
bridged by rigid organic molecules that assemble as highly porous
molecular "scaffolds". We will report on a novel application of
diffuse reflectance IR spectroscopy to probe the ro-vibrational modes
of molecular hydrogen adsorbed within these materials. Experiments
with H2, HD, and D2 illustrate the importance
of quantum mechanical considerations and the necessity for rotational
translational coupling models. Data reveal the propensity of exposed
metals sites to produce some of the largest recorded interaction
energies with adsorbed hydrogen. This leads to large frequency redshifts
in the H2 vibrational mode (65 - 130 cm-1) along
with a dramatic increase in the overtone intensity. The magnitude of
the effect is shown to follow the Irving-Williams sequence in which
the frequency shift for H2 bound to Ni2+ >
Co2+ > Zn2+.
Title: What Do High-resolution EIT Waves Tell Us About CMEs?
Authors: Thompson, Barbara; Biesecker, D. A.; Nitta, N.; Ofman, L.;
West, M. J.
Bibcode: 2010AAS...21640229T
Altcode:
Although many studies have demonstrated that some coronal waves are
not generated by coronal mass ejections, we have learned a great
deal about the ability of coronal mass ejections to drive large-scale
coronal waves, also called "EIT waves." We present new results based
on EIT wave amplitude, timing, speed, and direction of propagation,
with respect to their correlation with CME-related dimmings, speeds,
locations and widths. Furthermore, we demonstrate the ability to
correlate different aspects of EIT waves with some of the observed
structure of CMEs observed in coronagraph data. Finally, we expand
on the discussion of the types of wave modes that can be generated
by a coronal mass ejection, and how these observations can serve as a
diagnostic of the type of impulse a CME can deliver to the surrounding
corona. These diagnostics are obtained by examining the motion of
individual field lines, requiring high-resolution observations like
those provided by TRACE and SDO/AIA.
Title: Kinetic temperatures of iron ions in the solar wind observed
with STEREO/PLASTIC
Authors: Bochsler, Peter; Lee, Martin A.; Karrer, Reto; Popecki,
Mark A.; Galvin, Antoinette B.; Kistler, Lynn M.; Möbius, Eberhard;
Farrugia, Charles J.; Kucharek, Harald; Simunac, Kristin D. C.;
Blush, Lisa M.; Daoudi, Hagar; Wurz, Peter; Klecker, Berndt;
Wimmer-Schweingruber, Robert F.; Thompson, Barbara; Luhmann, Janet G.;
Jian, Lan K.; Russell, Christopher T.; Opitz, Andrea
Bibcode: 2010AIPC.1216..257B
Altcode:
STEREO/PLASTIC provides detailed information on the three-dimensional
velocity distributions of solar wind iron ions with a time
resolution of 5 minutes. In general the distributions at 1 AU contain
complicated structures showing persistence over several records,
i.e., over intervals of up to 30 minutes, but no clear correlation
of the properties of these distributions with the direction of the
ambient magnetic field is evident. We have performed a statistical
analysis using nearly 9000 observations. Iron ions follow the
same trends as protons, alpha particles, and electrons: The ratio
T⊥/T|| seems to be limited by the ion cyclotron
instability, whereas T||/T⊥ is bounded by the
firehose instability.
Title: Mini-RF Observations of a Sample of Large Lunar Pyroclastic
Deposits
Authors: Carter, L. M.; Gillis-Davis, J. J.; Bussey, D. B. J.; Spudis,
P. D.; Neish, C. D.; Thompson, B. J.; Patterson, G. W.; Raney, R. K.;
Mini-Rf Science Team
Bibcode: 2010LPI....41.1563C
Altcode:
We present new radar data of large lunar pyroclastic deposits obtained
using the Mini-RF instruments on Chandrayaan-1 and Lunar Reconnaissance
Orbiter, including the Orientale pyroclastic.
Title: Using Mini-RF to Investigate the Anomalous UVVIS Spectrum in
the Apollo and Plato Region
Authors: Trang, D.; Gillis-Davis, J. J.; Williams, K.; Bussey,
D. B. J.; Spudis, P. D.; Carter, L. M.; Neish, C. D.; Thompson, B.;
Patterson, W.
Bibcode: 2010LPI....41.2652T
Altcode:
Mini-RF radar data are used to examine the chemical and physical
properties of both Apollo and Plato regions.
Title: VizieR Online Data Catalog: A catalog of coronal "EIT wave"
transients (Thompson+, 2009)
Authors: Thompson, B. J.; Myers, D. C.
Bibcode: 2010yCat..21830225T
Altcode:
The catalog consists of all of the observations in the EIT 195Å images,
from January 1996 through June 1998, in which we were able to find
evidence of EIT wave-like phenomena. (2 data files).
Title: Major solar energetic particle events: The first 100 minutes
Authors: Kocharov, Leon; Klassen, Andreas; Reiner, Mike J.; Thompson,
Barbara; Ryan, James M.; Valtonen, Eino
Bibcode: 2010cosp...38.3002K
Altcode: 2010cosp.meet.3002K
Using spaceborne particle, EUV and gamma-ray detection and radio
spectrograms from both ground-based and spaceborne instruments, we
study the first phase of two major solar energetic particle (SEP)
events associated with solar eruptions centered at different solar
longitudes. The well-connected SEP event, observed onboard SOHO on 4
April 2000, starts with deka-MeV/n helium-and relativistic electron-rich
production from coronal sources identified with the electromagnetic
diagnostics. That production dominates during the first 100 min
of the event, and the coronal SEP sources at that time were not
shielded by the CME-bow shock between the Sun and the SOHO. The 12
September 2000 solar eruption was longitude-distant, with respect to
the Earth-connected heliolongitude, and onset of the first stage of
the SEP event observed on SOHO was delayed by an extra half hour. In
both cases, the first phase of the event was followed by a prolonged,
second-phase SEP production, and both events were associated with a
decelerating CME-driven shock in solar wind.
Title: If the Sun is so quiet, why is the Earth ringing? A comparison
of two solar minimum intervals
Authors: Gibson, S. E.; Kozyra, J. U.; de Toma, G.; Emery, B. A.;
Onsager, T. G.; Thompson, B. J.
Bibcode: 2009AGUFMSH11A1501G
Altcode:
A system-oriented analysis of new observations from the recent
international Whole Heliosphere Interval (WHI) campaign in comparison
with the equivalent Whole Sun Month (WSM) campaign from last cycle’s
minimum yields new insight into solar quiet intervals and the solar
minimum Sun-Earth system. We use a side-by-side comparison of these
two intervals to demonstrate that sunspot numbers, while providing a
good measure of solar activity, do not provide sufficient information
to gauge solar and heliospheric magnetic complexity and its effect
at the Earth. The present solar minimum is exceptionally quiet, with
sunspot numbers the lowest in 75 years, solar wind density and IMF
strength at the lowest values ever observed, and geomagnetic indices
and solar EUV fluxes the lowest in three solar cycles. Despite, or
perhaps because of this global weakness in the heliospheric magnetic
field, large near-equatorial coronal holes lingered even as the
sunspots disappeared, indicating significant open magnetic flux at low
latitudes. Consequently, for the months surrounding the WHI campaign,
strong, long, and recurring high-speed streams in the solar wind
intercepted the Earth in contrast to the weaker and more sporadic
streams that occurred around the time of the WSM campaign. Since
the speed, duration and southward magnetic field component in wind
streams determine the severity of space weather effects, the geospace
environment responded quite differently to the two solar minimum
heliospheric morphologies. We illustrate this point with the behavior
of relativistic electrons in the Earth’s outer radiation belt, which
were more than three times stronger during WHI than in WSM. The cause
is clear: it is well-known that high-speed streams drive radiation belt
population, and indeed, for the months surrounding WHI, geospace and
upper atmospheric parameters were ringing with the periodicities of
the solar wind in a manner that was absent last cycle minimum. Such
behavior could not have been predicted using sunspot numbers alone,
indicating the importance of considering variation within and between
solar minima in analyzing and predicting space weather responses at
the Earth during solar quiet intervals, as well as in interpreting the
Sun’s past behavior as preserved in geological and historical records.
Title: Recent STEREO Observations of Coronal Mass Ejections
Authors: St Cyr, O. C.; Xie, H.; Mays, M. L.; Davila, J. M.; Gilbert,
H. R.; Jones, S. I.; Pesnell, W. D.; Gopalswamy, N.; Gurman, J. B.;
Yashiro, S.; Wuelser, J.; Howard, R. A.; Thompson, B. J.; Thompson,
W. T.
Bibcode: 2009AGUFMSH11A1491S
Altcode:
Over 400 CMEs have been observed by STEREO SECCHI COR1 during
the mission's three year duration (2006-2009). Many of the solar
activity indicators have been at minimal values over this period,
and the Carrington rotation-averaged CME rate has been comparable to
that measured during the minima between Cycle 21-22 (SMM C/P) and
Cycle 22-23 (SOHO LASCO). That rate is about 0.5 CMEs/day. During
the current solar minimum (leading to Cycle 24), there have been
entire Carrington rotations where no sunspots were detected and the
daily values of the 2800 MHz solar flux remained below 70 sfu. CMEs
continued to be detected during these exceptionally quiet periods,
indicating that active regions are not necessary to the generation of
at least a portion of the CME population. In the past, researchers were
limited to a single view of the Sun and could conclude that activity
on the unseen portion of the disk might be associated with CMEs. But
as the STEREO mission has progressed we have been able to observe an
increasing fraction of the Sun's corona with STEREO SECCHI EUVI and
were able to eliminate this possibility. Here we report on the nature
of CMEs detected during these exceptionally-quiet periods, and we
speculate on how the corona remains dynamic during such conditions.
Title: Evolution of CMEs in the Heliosphere at Solar Minimum
Authors: Plunkett, S. P.; Wood, B. E.; Odstrcil, D.; Riley, P.;
Thompson, B. J.; Szabo, A.
Bibcode: 2009AGUFMSH43A..06P
Altcode:
The STEREO mission permits CMEs to be observed all the way from the Sun
through the inner heliosphere to beyond the orbit of the Earth, from a
vantage point away from the Sun-Earth line. We combine remotely-sensed
imaging and in-situ observations of CMEs from STEREO and other missions
with modeling of selected events to better understand how CMEs evolve
as they propagate out from the Sun into the heliosphere, and to study
the relationship between CMEs observed in imaging instruments and
ICMEs observed in-situ. We present preliminary results from analysis
and modeling of a small number of well-observed CME events during the
present solar minimum period. These include the event of April 26,
2008 and the Earth-directed event on December 12, 2008.
Title: In Situ Observations of Solar Wind Stream Interface Evolution
Authors: Simunac, K. D. C.; Kistler, L. M.; Galvin, A. B.; Lee, M. A.;
Popecki, M. A.; Farrugia, C.; Moebius, E.; Blush, L. M.; Bochsler,
P.; Wurz, P.; Klecker, B.; Wimmer-Schweingruber, R. F.; Thompson,
B.; Luhmann, J. G.; Russell, C. T.; Howard, R. A.
Bibcode: 2009SoPh..259..323S
Altcode:
The heliocentric orbits of the two STEREO satellites are similar in
radius and ecliptic latitude, with separation in longitude increasing
by about 45° per year. This arrangement provides a unique opportunity
to study the evolution of stream interfaces near 1 AU over time scales
of hours to a few days, much less than the period of a Carrington
rotation. Assuming nonevolving solar wind sources that corotate with
the Sun, we calculated the expected time and longitude of arrival of
stream interfaces at the Ahead observatory based on the in situ solar
wind speeds measured at the Behind observatory. We find agreement to
within 5° between the expected and actual arrival longitude until the
spacecraft are separated by more than 20° in heliocentric inertial
longitude. This corresponds to about one day between the measurement
times. Much larger deviations, up to 25° in longitude, are observed
after 20° separation. Some of the deviations can be explained by a
latitude difference between the spacecraft, but other deviations most
likely result from evolution of the source region. Both remote and in
situ measurements show that changes at the source boundary can occur on
a time scale much shorter than one solar rotation. In 32 of 41 cases,
the interface was observed earlier than expected at STEREO/Ahead.
Title: Solar wind ion trends and signatures: STEREO PLASTIC
observations approaching solar minimum
Authors: Galvin, A. B.; Popecki, M. A.; Simunac, K. D. C.; Kistler,
L. M.; Ellis, L.; Barry, J.; Berger, L.; Blush, L. M.; Bochsler, P.;
Farrugia, C. J.; Jian, L. K.; Kilpua, E. K. J.; Klecker, B.; Lee,
M.; Liu, Y. C. -M.; Luhmann, J. L.; Moebius, E.; Opitz, A.; Russell,
C. T.; Thompson, B.; Wimmer-Schweingruber, R. F.; Wurz, P.
Bibcode: 2009AnGeo..27.3909G
Altcode:
STEREO has now completed the first two years of its mission, moving
from close proximity to Earth in 2006/2007 to more than 50 degrees
longitudinal separation from Earth in 2009. During this time, several
large-scale structures have been observed in situ. Given the prevailing
solar minimum conditions, these structures have been predominantly
coronal hole-associated solar wind, slow solar wind, their interfaces,
and the occasional transient event. In this paper, we extend earlier
solar wind composition studies into the current solar minimum using
high-resolution (1-h) sampling times for the charge state analysis. We
examine 2-year trends for iron charge states and solar wind proton
speeds, and present a case study of Carrington Rotation 2064 (December
2007) which includes minor ion (He, Fe, O) kinetic and Fe composition
parameters in comparison with proton and magnetic field signatures at
large-scale structures observed during this interval.
Title: If the Sun is so quiet, why is the Earth ringing? A comparison
of two solar minimum intervals
Authors: Gibson, S. E.; Kozyra, J. U.; de Toma, G.; Emery, B. A.;
Onsager, T.; Thompson, B. J.
Bibcode: 2009JGRA..114.9105G
Altcode: 2009JGRA..11409105G
Observations from the recent Whole Heliosphere Interval (WHI) solar
minimum campaign are compared to last cycle's Whole Sun Month (WSM)
to demonstrate that sunspot numbers, while providing a good measure of
solar activity, do not provide sufficient information to gauge solar
and heliospheric magnetic complexity and its effect at the Earth. The
present solar minimum is exceptionally quiet, with sunspot numbers at
their lowest in 75 years and solar wind magnetic field strength lower
than ever observed. Despite, or perhaps because of, a global weakness
in the heliospheric magnetic field, large near-equatorial coronal
holes lingered even as the sunspots disappeared. Consequently, for
the months surrounding the WHI campaign, strong, long, and recurring
high-speed streams in the solar wind intercepted the Earth in contrast
to the weaker and more sporadic streams that occurred around the
time of last cycle's WSM campaign. In response, geospace and upper
atmospheric parameters continued to ring with the periodicities of
the solar wind in a manner that was absent last cycle minimum, and the
flux of relativistic electrons in the Earth's outer radiation belt was
elevated to levels more than three times higher in WHI than in WSM. Such
behavior could not have been predicted using sunspot numbers alone,
indicating the importance of considering variation within and between
solar minima in analyzing and predicting space weather responses at
the Earth during solar quiet intervals, as well as in interpreting the
Sun's past behavior as preserved in geological and historical records.
Title: Evolution of CMEs in the Heliosphere
Authors: Plunkett, Simon P.; Wood, Brian E.; Thompson, Barbara J.;
Szabo, Adam; Odstrcil, Dusan; Riley, Pete
Bibcode: 2009shin.confE.117P
Altcode:
The STEREO mission permits CMEs to be observed all the way from the Sun
through the inner heliosphere to beyond the orbit of the Earth, from a
vantage point away from the Sun-Earth line. We combine remotely-sensed
imaging and in-situ observations of CMEs from STEREO and other missions
with modeling of selected events to better understand how CMEs evolve
as they propagate out from the Sun into the heliosphere, and to study
the relationship between CMEs observed in imaging instruments and
ICMEs observed in-situ. We present preliminary results from analysis
and modeling of a small number of well-observed CME events during the
present solar minimum period. These include the events of April 26,
2008, May 17, 2008, and the Earth-directed event on December 12, 2008.
Title: Analysis of Suprathermal Events Observed by STEREO/PLASTIC
with a Focus on Upstream Events
Authors: Barry, Joshua Adam; Galvin, Antoinette; Popecki, Mark; Ellis,
Lorna; Kucharek, Harald; Lee, Marty; Simunac, Kristin; Farrugia,
Charlie; Moebius, Eberhard; Kistler, Lynn; Klecker, Berndt; Luhmann,
Janet; Russell, Christopher T.; Bochsler, Peter; Wurz, Peter; Wimmer,
Robert; Thompson, Barbara
Bibcode: 2009shin.confE..94B
Altcode:
Since the late 1960's, suprathermal and energetic ion events with
energies ranging from just above the solar wind energies up to 2MeV
and lasting for several minutes to hours, have been detected upstream
of the Earth. Possible sources of these ions include magnetospheric
ions, solar wind ions accelerated between the Earth's bow shock and
hydromagnetic waves to energies just above the solar wind energies,
and remnant ions from heliospheric processes (such as Solar Energetic
Particle (SEP) events or Corotating Interaction Regions (CIRs)). The
unique orbits of both STEREO spacecraft, STEREO-A (STA) drifting ahead
in Earth's orbit and STEREO-B (STB) lagging behind in Earth's orbit,
allow for analysis of upstream events in these unexamined regions. Using
both the PLASTIC and IMPACT instruments on board STA/B we can examine
protons in the energy range of solar wind energies up to 80keV, their
spatial distribution, and attempt to determine if the spacecraft is
magnetically connected to the Earth's bow shock. Suprathermal events
observed by STEREO/PLASTIC on STA during solar minimum conditions are
examined for possible upstream events using anisotropy measurements,
velocity dispersion, magnetic connection to the bow shock, and frequency
of events as a function of time and distance.
Title: A Catalog of Coronal "EIT Wave" Transients
Authors: Thompson, B. J.; Myers, D. C.
Bibcode: 2009ApJS..183..225T
Altcode:
Solar and Heliospheric Observatory (SOHO) Extreme ultraviolet
Imaging Telescope (EIT) data have been visually searched for coronal
"EIT wave" transients over the period beginning from 1997 March 24
and extending through 1998 June 24. The dates covered start at the
beginning of regular high-cadence (more than 1 image every 20 minutes)
observations, ending at the four-month interruption of SOHO observations
in mid-1998. One hundred and seventy six events are included in this
catalog. The observations range from "candidate" events, which were
either weak or had insufficient data coverage, to events which were
well defined and were clearly distinguishable in the data. Included
in the catalog are times of the EIT images in which the events are
observed, diagrams indicating the observed locations of the wave fronts
and associated active regions, and the speeds of the wave fronts. The
measured speeds of the wave fronts varied from less than 50 to over 700
km s-1 with "typical" speeds of 200-400 km s-1.
Title: Pickup Helium at Stream Interfaces and Corotating Interaction
Regions.
Authors: Kucharek, Harald; Klecker, B.; Möbius, E.; Simunac, K. D. C.;
Galvin, A. B.; Barry, J.; Bochsler, P.; Blush, L.; Ellis, L.; Farrugia,
C.; Kistler, L. M.; Lee, M.; Luhmann, J.; Popecki, M. A.; Russell,
C. T.; Thompson, B.; Wimmer-Schweingruber, R.
Bibcode: 2009shin.confE..34K
Altcode:
Pickup ion measurements using AMPTE, Ulysses, SOHO, Wind and ACE
have demonstrated that pickup ion fluxes can vary over a wide range
and that the shape of the distributions can change substantially on
time scales from less than one hour to many days. These variations
have been attributed to changes in the interplanetary magnetic field
(IMF) which may manifest themselves in incomplete pickup, density
compressions or rarefactions, and shocks. Suprathermal tails may play a
significant role because these energetic ions could form a seed particle
population for further acceleration. Yet, the vast majority of the
observed temporal variations remain unexplained and it is unknown
at what distance of the spacecraft the acceleration occurs. High
resolution and simultaneous observations of pickup ion distributions
with the Plasma and Suprathermal Ion Composition (PLASTIC) instrument
on board STEREO A and B, two spatially-separated spacecraft, provide
an opportunity to follow the temporal and spatial structures of pickup
ion variations. Furthermore, its Wide Angle Partition (WAP) provides
direction information. STEREO spacecraft have encountered numerous
large-scale interplanetary disturbances such as Stream Interfaces
(SIs) and Corotating Interaction Regions (CIRs). In this presentation
we will present helium pickup ion spectra and fluxes as a function of
solar wind and IMF parameters, focusing on their spatial and temporal
evolution. For selected events we will also determine the location of
the acceleration region relative to the spacecraft location.
Title: Joint LROC - Mini-RF Observations: Opportunities and Benefits
Authors: Nozette, S.; Bussey, D. B. J.; Butler, B.; Carter, L.;
Gillis-Davis, J.; Goswami, J.; Heggy, E.; Kirk, R.; Misra, T.;
Patterson, G. W.; Robinson, M.; Raney, R. K.; Spudis, P. D.; Thompson,
T.; Thompson, B.; Ustinov, E.
Bibcode: 2009LPICo1483...84N
Altcode:
No abstract at ADS
Title: Temporal Evolution of the Solar Wind Bulk Velocity at Solar
Minimum by Correlating the STEREO A and B PLASTIC Measurements
Authors: Opitz, A.; Karrer, R.; Wurz, P.; Galvin, A. B.; Bochsler,
P.; Blush, L. M.; Daoudi, H.; Ellis, L.; Farrugia, C. J.; Giammanco,
C.; Kistler, L. M.; Klecker, B.; Kucharek, H.; Lee, M. A.; Möbius,
E.; Popecki, M.; Sigrist, M.; Simunac, K.; Singer, K.; Thompson, B.;
Wimmer-Schweingruber, R. F.
Bibcode: 2009SoPh..256..365O
Altcode:
The two STEREO spacecraft with nearly identical instrumentation were
launched near solar activity minimum and they separate by about 45°
per year, providing a unique tool to study the temporal evolution of the
solar wind. We analyze the solar wind bulk velocity measured by the two
PLASTIC plasma instruments onboard the two STEREO spacecraft. During the
first half year of our measurements (March - August 2007) we find the
typical alternating slow and fast solar wind stream pattern expected at
solar minimum. To evaluate the temporal evolution of the solar wind bulk
velocity we exclude the spatial variations and calculate the correlation
between the solar wind bulk velocity measured by the two spacecraft. We
account for the different spacecraft positions in radial distance and
longitude by calculating the corresponding time lag. After adjusting
for this time lag we compare the solar wind bulk velocity measurements
at the two spacecraft and calculate the correlation between the two
time-shifted datasets. We show how this correlation decreases as the
time difference between two corresponding measurements increases. As
a result, the characteristic temporal changes in the solar wind bulk
velocity can be inferred. The obtained correlation is 0.95 for a time
lag of 0.5 days and 0.85 for 2 days.
Title: Constraints on Aeolian Degradation Rates on Mars from Erasure
of Rover Tracks
Authors: Geissler, P. E.; Arvidson, R.; Bell, J.; Bridges, N.;
Desouza, P.; Golombek, M.; Greenberger, R.; Greeley, R.; Herkenhoff,
K.; Lahtela, H.; Johnson, J. R.; Landis, G.; Li, R.; Moersch, J.;
Richter, L.; Sims, M.; Soderblom, J.; Sullivan, R.; Thompson, B.;
Verba, C. A.; Waller, D.; Wang, A.; HiRISE Team; Mer Team
Bibcode: 2009LPI....40.2257G
Altcode:
Surface and orbital observations of the erasure of the wheel tracks
made by the MER rovers Spirit and Opportunity provide insights into
the mechanisms and timescales of aeolian degradation on Mars.
Title: The STEREO/PLASTIC response to solar wind ions (Flight
measurements and models)
Authors: Daoudi, H.; Blush, L. M.; Bochsler, P.; Galvin, A. B.;
Giammanco, C.; Karrer, R.; Opitz, A.; Wurz, P.; Farrugia, C.;
Kistler, L. A.; Popecki, M. A.; Möbius, E.; Singer, K.; Klecker,
B.; Wimmer-Schweingruber, R. F.; Thompson, B.
Bibcode: 2009ASTRA...5....1D
Altcode:
The Plasma and Supra-Thermal Ion Composition (PLASTIC) instrument is
one of four experiment packages on board of the two identical STEREO
spacecraft A and B, which were successfully launched from Cape Canaveral
on 26 October 2006. During the two years of the nominal STEREO mission,
PLASTIC is providing us with the plasma characteristics of protons,
alpha particles, and heavy ions. PLASTIC will also provide key
diagnostic measurements in the form of the mass and charge state
composition of heavy ions. Three measurements (E/qk,
time of flight, ESSD) from the pulse height raw data are
used to characterize the solar wind ions from the solar wind sector,
and part of the suprathermal particles from the wide-angle partition
with respect to mass, atomic number and charge state. In this paper,
we present a new method for flight data analysis based on simulations
of the PLASTIC response to solar wind ions. We present the response of
the entrance system / energy analyzer in an analytical form. Based on
stopping power theory, we use an analytical expression for the energy
loss of the ions when they pass through a thin carbon foil. This
allows us to model analytically the response of the time of flight
mass spectrometer to solar wind ions. Thus we present a new version
of the analytical response of the solid state detectors to solar wind
ions. Various important parameters needed for our models were derived,
based on calibration data and on the first flight measurements obtained
from STEREO-A. We used information from each measured event that is
registered in full resolution in the Pulse Height Analysis words and we
derived a new algorithm for the analysis of both existing and future
data sets of a similar nature which was tested and works well. This
algorithm allows us to obtain, for each measured event, the mass, atomic
number and charge state in the correct physical units. Finally, an
important criterion was developed for filtering our Fe raw flight data
set from the pulse height data without discriminating charge states.
Title: Universal processes in heliophysics
Authors: Davila, Joseph M.; Gopalswamy, Nat; Thompson, Barbara J.
Bibcode: 2009IAUS..257...11D
Altcode:
The structure of the Universe is determined primarily by the interplay
of gravity which is dominant in condensed objects, and the magnetic
force which is dominant in the rarefied medium between condensed
objects. Each of these forces orders the matter into a set of
characteristic structures each with the ability to store and release
energy in response to changes in the external environment. For the
most part, the storage and release of energy proceeds through a number
of Universal Processes. The coordinated study of these processes in
different settings provides a deeper understanding of the underlying
physics governing Universal Processes in astrophysics.
Title: Putting the "I" in IHY: The United Nations Report for the
International Heliophysical Year 2007
Authors: Thompson, Barbara J.; Gopalswamy, Natchimuthuk; Davila,
Joseph M.; Haubold, Hans J.
Bibcode: 2009piih.rept.....T
Altcode:
No abstract at ADS
Title: Analysis of Suprathermal Events Observed by STEREO/PLASTIC
Authors: Barry, J. A.; Galvin, A. B.; Farrugia, C. J.; Popecki, M.;
Klecker, B.; Ellis, L.; Lee, M. A.; Kistler, L. M.; Luhmann, J. G.;
Russell, C. T.; Simunac, K.; Kucharek, H.; Blush, L.; Bochsler, P.;
Möbius, E.; Thompson, B. J.; Wimmer-Schweingruber, R.; Wurz, P.
Bibcode: 2008AGUFMSH31B1671B
Altcode:
Since the late 1960's, suprathermal and energetic ion events with
energies ranging from just above the solar wind energies up to 2MeV
and lasting for several minutes to hours, have been detected upstream
of the Earth. Possible sources of these ions include magnetospheric
ions, solar wind ions accelerated between the Earth's bow shock and
hydromagnetic waves to energies just above the solar wind energies,
and remnant ions from heliospheric processes (such as Solar Energetic
Particle (SEP) events or Corotating Interaction Regions (CIRs)). The
unique orbits of both STEREO spacecraft, STEREO-A (STA) drifting ahead
in Earth's orbit and STEREO-B (STB) lagging behind in Earth's orbit,
allow for analysis of upstream events in these unexamined regions. Using
both the PLASTIC and IMPACT instruments on board STA/B we can examine
protons in the energy range of solar wind energies up to 80keV, their
spatial distribution, and determine if the spacecraft is magnetically
connected to the Earth's bow shock. Suprathermal events observed by
STEREO/PLASTIC during solar minimum conditions are examined for possible
upstream events using anisotropy measurements, velocity dispersion,
magnetic connection to the bow shock, and frequency of events as a
function of time and distance.
Title: Outreach activities during the 2006 total solar eclipse
sponsored by the International Heliophysical Year
Authors: Rabello Soares, M. C.; Rabiu, A. B.; Gopalswamy, N.; Thompson,
B. J.; Davila, J. M.; Sobrinho, A. A.
Bibcode: 2008AdSpR..42.1792R
Altcode:
The International Heliophysical Year (IHY) is an international program
of scientific research to advance our understanding of the physical
processes that govern the Sun, Earth and heliosphere. It has a strong
educational component, linking research and education. Here, we describe
the outreach activities during the 2006 total solar eclipse sponsored
by IHY.
Title: Temporal and Spatial Variations of Pickup Ions seen on
STEREO/PLASTIC
Authors: Kucharek, H.; Klecker, B.; Simunac, K.; Russell, C.; Moebius,
E.; Popecki, M.; Galvin, A.; Kistler, L.; Ellis, L.; Gustafson, A.;
Barry, J.; Singer, K.; Farrugia, C.; Lee, M.; Blush, L.; Karrer,
R.; Bochsler, P.; Wurz, P.; Wimmer-Schweingruber, R.; Thompson, B.;
Luhmann, J.
Bibcode: 2008AGUFMSH21B1605K
Altcode:
Pickup ions seem to be a perfect tracer of interplanetary
discontinuities in the heliosphere and they provide important
information on acceleration processes at these structures and in the
turbulent solar wind (i.e. suprathermal tails). Studies of pickup ions
using AMPTE, Ulysses, SOHO, Wind and ACE demonstrated that pickup ion
fluxes and the shape of their distributions can vary substantially on
time scales from less than one hour to many days. These variations have
been attributed to changes in the interplanetary magnetic field (IMF)
direction and strength in the sense of incomplete pickup and/or density
compressions and decompressions. For instance, at CIRs one observes
the most intense and most prolonged enhancements of energetic helium
pickup ions. At present, the vast majority of the observed temporal
variations remain unexplained. Furthermore, spatial variations of
pickup ion distributions could not be studied with single spacecraft
observation. Simultaneous observations of pickup ion distributions with
the PLASTIC instrument on STEREO A and B now provide the opportunity
to follow pickup ion variations on spatial scales from a few 106 km
to 108 km. In the early mission phase STEREO A and B were often along
the same magnetic field flux tubes. This allows us to study temporal
effects. With increasing spacecraft separation spatial effects can
be studied. In this presentation we will show STEREO observations of
helium pickup ion spectra and fluxes for 2007/8 in their dependence
on solar wind density, speed and flux as well IMF direction and
strength on both spacecraft. We then determined whether the observed
variations are mainly correlated features that are associated with
spatial structures passing the STEREO spacecraft at different times
(such as CIRs or the focusing cone), or whether they have a substantial
uncorrelated component indicative of temporal variations.
Title: Oxygen Observations by STEREO/PLASTIC in the Slow Solar Wind
Authors: Liu, Y. C.; Galvin, A. B.; Simunac, K. D.; Kistler, L. M.;
Popecki, M. A.; Farrugia, C. F.; Ellis, L.; Mobius, E.; Lee, M. A.;
Zurbuchen, T. H.; Lepri, S.; Blush, L. M.; Bochsler, P.; Daoudi, H.;
Wurz, P.; Wimmer-Schweingruber, R. F.; Klecker, B.; Thompson, B.
Bibcode: 2008AGUFMSH51B1604L
Altcode:
We have analyzed solar wind oxygen in the data from the STEREO Plasma
and Supra-thermal Ion Composition Experiment (PLASTIC). For this initial
study we concentrate on the slow solar wind where the ion composition
is stable, different ion species have nearly the same bulk speed,
and the kinetic temperature is usually low. The mass of the detected
ions is determined when the ions have both a valid time-of-flight
and a residual energy measured by a Solid State Detector (SSD). The
bulk speed, thermal speed and flow angles of O6+ are then calculated
using the electrostatic analyzer and position data. The STEREO data
are compared to similar measurement on ACE/SWICS.
Title: The Whole Heliosphere Interval: Campaign Summaries and
Early Results
Authors: Thompson, B.; Gibson, S. E.; McIntosh, S.; Fuller-Rowell,
T.; Galvin, A. B.; Kozyra, J. U.; Petrie, G.; Schroeder, P.; Strachan,
L.; Webb, D. F.; Woods, T.
Bibcode: 2008AGUFMSH21C..01T
Altcode:
The Whole Heliosphere Interval (WHI) is an internationally coordinated
observing and modeling effort to characterize the 3-dimensional
interconnected solar-heliospheric-planetary system - a.k.a. the
"heliophysical" system. The heart of the WHI campaign is the study
of the interconnected 3-D heliophysical domain, from the interior
of the Sun, to the Earth, outer planets, and into interstellar
space. WHI observing campaigns began with the 3-D solar structure from
solar Carrington Rotation 2068, which ran from March 20 - April 16,
2008. Observations and models of the outer heliosphere and planetary
impacts extend beyond those dates as necessary; for example, the
solar wind transit time to outer planets can take months. WHI occurred
during solar minimum, which optimizes our ability to characterize the
3-D heliosphere and trace the structure to the outer limits of the
heliosphere. Highlights include the 3-D reconstruction of the solar
wind and complex geospace response during this solar minimum, contrasts
with the past solar minimum, and the effect of transient activity on the
"quiet" heliosphere. Nearly 200 scientists are participated in WHI data
and modeling efforts, ensuring that the WHI integrated observations
and models will give us a "new view" of the heliophysical system. A
summary of some of the key results from the WHI first workshop in
August 2008 will be given.
Title: Constructing a Data System to Support Analysis of the Whole
Heliosphere Interval
Authors: Thompson, B. J.; Schroeder, P. C.; Gibson, S. E.
Bibcode: 2008AGUFMSH23A1632T
Altcode:
The Whole Heliosphere Interval is an internationally coordinated
observing and modeling effort to characterize the 3-dimensional
interconnected solar-heliospheric-planetary system. The WHI observing
campaigns began with the 3-D solar structure from solar Carrington
Rotation 2068, which ran from March 20 to April 16, 2008, and traced
these structures through the heliosphere and into geospace. The WHI
team has developed a data and modeling clearinghouse to create a
unified point of entry into the disparate data sets spanning across
the traditional disciplinary boundaries. Linkages are provided to data
from the special observing programs conducted by many observatories
for the WHI effort, models that looked in detail at the WHI and the
many other data sets and models from the interval. We also explore
the Virtual Observatory landscape and highlight their contributions
to the development of a more complete understanding of the entire
heliophysical system.
Title: Constraints on Aeolian Degradation Rates on Mars from Erasure
of Rover Tracks
Authors: Geissler, P. E.; Arvidson, R.; Bell, J.; Bridges, N.; de
Souza, P.; Golombek, M.; Greenberger, R.; Greeley, R.; Herkenhoff,
K.; Lahtela, H.; Landis, G.; Li, R.; Moersch, J.; Richter, L.; Sims,
M.; Soderblom, J.; Sullivan, R.; Thompson, B.; Verba, C.; Waller,
D.; Wang, A.; Team, H.; Team, M.
Bibcode: 2008AGUFM.P53A1434G
Altcode:
The wheel tracks left by the MER rovers Spirit and Opportunity are
unique artificial markings on the surface of Mars. The tracks stretch
several kilometers across diverse terrain in two widely separated
regions of the planet. The initial appearance and characteristics of the
tracks were well documented by the science and navigation cameras aboard
the vehicles at the time the tracks were formed. Orbital observations
by Mars Global Surveyor and now Mars Reconnaissance Orbiter document the
erasure of the tracks over a period of more than two Mars years. We are
studying the erasure of the rover tracks as a means to better understand
the mechanisms and time-scales of aeolian degradation on Mars. Spirit's
wheels left conspicuous dark tracks in the dust-mantled soil of Gusev
crater. Low albedo sand and gravel were exposed from beneath the bright
dust mantle along Spirit's traverse from its landing site across the
Columbia Hills. High albedo, silica-rich soils were ploughed up near
Home Plate by the rover's stuck right front wheel. MOC images show
that the tracks near the landing site began to fade gradually in the
weeks after they were made. Atmospheric dust fallout and summertime
dust-devils rendered Spirit's tracks invisible before the arrival of
MRO. Only two small sections of tracks from Spirit's traverse to Home
Plate can still be seen in recent HiRISE images, on the southern flanks
of Husband Hill and in the corridor west of Mitcheltree Ridge. Spirit
witnessed the episodic erasure of its tracks at the height of the
global dust storm of 2007, when strong surface winds blew away the
tracks and shifted the soil surrounding the rover over a period of
just days. Opportunity's tracks across Meridiani Planum to Victoria
crater were barely visible at the time that they were made, and had
largely disappeared before the arrival of MRO. Opportunity's tracks
are slightly brighter than the undisturbed surface because the wheels
press the darker hematite spherules into the soft soil. Only two short
sections of pre-2006 tracks remain visible in recent HiRISE images,
near the craters Fram and Erebus. However, the rover left conspicuous
bright tracks in the smooth annulus surrounding Victoria crater as she
traversed the crater's northern rim. Surprisingly, these tracks were
scarcely altered by the 2007 dust storm, despite clear changes in the
pattern of wind streaks emanating from the crater. Understanding the
time-scales and mechanisms of erasure of the rover tracks is important
for constraining the age of the many pristine impact craters that have
been discovered by MRO. In turn, this knowledge lets us place bounds
on the present day bombardment rate of Mars.
Title: International Heliophysical Year 2007: A Report from the
UN/NASA Workshop Bangalore, India, 27 November 1 December 2006
Authors: Davila, Joe; Gopalswamy, Nat; Thompson, Barbara; Haubold,
Hans J.
Bibcode: 2008EM&P..103....9D
Altcode: 2008EM&P..tmp...19D
The IHY Secretariat and the United Nations Basic Space Science
Initiative (UNBSSI) assist scientists and engineers from all over the
world in participating in the International Heliophysical Year (IHY)
2007. A major thrust of IHY/UNBSSI is to deploy arrays of small,
inexpensive instruments such as magnetometers, radio telescopes,
GPS receivers, all-sky cameras, etc. around the world to allow
global measurements of ionospheric and heliospheric phenomena. The
small instrument programme is envisioned as a partnership between
instrument providers and instrument hosts in developing nations. The
IHY/UNBSSI can facilitate the deployment of several of these networks
world-wide. Existing data bases and relevant software tools will
be identified to promote space science activities in developing
nations. Extensive data on space science have been accumulated by a
number of space missions. Similarly, long-term data bases are available
from ground-based observations. These data can be utilized in ways
different from originally intended for understanding the heliophysical
processes. This paper provides a comprehensive overview of IHY/UNBSSI,
its achievements, future plans, and outreach to the 192 Member States
of the United Nations as recorded in the UN/NASA workshop in India.
Title: Polar Gateways Arctic Circle Sunrise Conference 2008, Barrow,
Alaska: IHY-IPY Outreach on Exploration of Polar and Icy Worlds in
The Solar System
Authors: Cooper, John F.; Kauristie, K.; Weatherwax, A. T.; Sheehan,
G. W.; Smith, R. W.; Sandahl, I.; Østgaard, N.; Chernouss, S.; Moore,
M. H.; Peticolas, L. M.; Senske, D. A.; Thompson, B. J.; Tamppari,
L. K.; Lewis, E. M.
Bibcode: 2008DPS....40.1813C
Altcode: 2008BAAS...40..420C
Polar, heliophysical, and planetary science topics related to the
International Heliophysical and Polar Years 2007-2009 were addressed
during this circumpolar video conference hosted January 23-29,
2008 at the new Barrow Arctic Research Center of the Barrow Arctic
Science Consortium in Barrow, Alaska. This conference was planned as
an IHY-IPY event science outreach event bringing together scientists
and educational specialists for the first week of sunrise at subzero
Arctic temperatures in Barrow. Science presentations spanned the
solar system from the polar Sun to Earth, Moon, Mars, Jupiter, Saturn,
and the Kuiper Belt. On-site participants experienced look and feel
of icy worlds like Europa and Titan by being in the Barrow tundra
and sea ice environment and by going "on the ice" during snowmobile
expeditions to the near-shore sea ice environment and to Point Barrow,
closest geographic point in the U.S. to the North Pole. Many science
presentations were made remotely via video conference or teleconference
from Sweden, Norway, Russia, Canada, Antarctica, and the United States,
spanning up to thirteen time zones (Alaska to Russia) at various
times. Extensive educational outreach activities were conducted with
the local Barrow and Alaska North Slope communities and through the NASA
Digital Learning Network live from the "top of the world" at Barrow. The
Sun-Earth Day team from Goddard, and a videographer from the Passport
to Knowledge project, carried out extensive educational interviews with
many participants and native Inupiaq Eskimo residents of Barrow. Video
and podcast recordings of selected interviews are available at
http://sunearthday.nasa.gov/2008/multimedia/podcasts.php. Excerpts from
these and other interviews will be included in a new high definition
video documentary called "From the Sun to the Stars: The New Science
of Heliophysics" from Passport to Knowledge that will later broadcast
on NASA TV and other educational networks. Full conference proceedings
are accessible at http://polargateways2008.org/.
Title: Whole Heliosphere Interval: Introduction
Authors: Gibson, S. E.; Thompson, B. J.; Webb, D.
Bibcode: 2008AGUSMSH53A..01G
Altcode:
The Whole Heliosphere Interval (WHI) is an international coordinated
observing and modeling effort to characterize the three-dimensional
interconnected solar-heliospheric-planetary system at solar minimum,
using observations originating at the Sun during Carrington Rotation
2067: March 20 - April 16, 2008. WHI's science begins with the solar
interior and extends through the heliosphere and interplanetary
space out to the heliopause. WHI is a special campaign period of the
International Heliophysical Year, and involves the participation of
many observatories and researchers around the world. A "synoptic" set
of observations provides baseline measurements of the heliophysical
system, while "targeted" observing campaigns during the WHI interval
focuses on particular sub-regions of the coupled heliospheric system
and address specific scientific questions via day-to-day coordinated
observations. This introductory talk will begin this special session
dedicated to providing a broad description of the heliosphere at solar
minimum by showcasing early results of the WHI campaign.
Title: Geospace, Heliospheric and Solar Data collected during the
Whole Heliosphere Interval
Authors: Thompson, B. J.; Gibson, S. E.; Webb, D. F.
Bibcode: 2008AGUSMSH51A..01T
Altcode:
The Whole Heliosphere Interval is a comprehensive observing and
modeling campaign that seeks to connect variations in the Earth's
ionosphere and magnetosphere with structure and energy variations in
the heliosphere and solar corona. Hundreds of researchers from around
the world participated by performing observations and contributing
data from an extensive array of sources. This poster will summarize
the observations taking during WHI, including special observations
performed under the targeted observing campaigns.
Title: The Plasma and Suprathermal Ion Composition (PLASTIC)
Investigation on the STEREO Observatories
Authors: Galvin, A. B.; Kistler, L. M.; Popecki, M. A.; Farrugia,
C. J.; Simunac, K. D. C.; Ellis, L.; Möbius, E.; Lee, M. A.; Boehm,
M.; Carroll, J.; Crawshaw, A.; Conti, M.; Demaine, P.; Ellis, S.;
Gaidos, J. A.; Googins, J.; Granoff, M.; Gustafson, A.; Heirtzler,
D.; King, B.; Knauss, U.; Levasseur, J.; Longworth, S.; Singer, K.;
Turco, S.; Vachon, P.; Vosbury, M.; Widholm, M.; Blush, L. M.; Karrer,
R.; Bochsler, P.; Daoudi, H.; Etter, A.; Fischer, J.; Jost, J.; Opitz,
A.; Sigrist, M.; Wurz, P.; Klecker, B.; Ertl, M.; Seidenschwang, E.;
Wimmer-Schweingruber, R. F.; Koeten, M.; Thompson, B.; Steinfeld, D.
Bibcode: 2008SSRv..136..437G
Altcode: 2008SSRv..tmp....5G
The Plasma and Suprathermal Ion Composition (PLASTIC) investigation
provides the in situ solar wind and low energy heliospheric
ion measurements for the NASA Solar Terrestrial Relations
Observatory Mission, which consists of two spacecraft (STEREO-A,
STEREO-B). PLASTIC-A and PLASTIC-B are identical. Each PLASTIC is
a time-of-flight/energy mass spectrometer designed to determine the
elemental composition, ionic charge states, and bulk flow parameters of
major solar wind ions in the mass range from hydrogen to iron. PLASTIC
has nearly complete angular coverage in the ecliptic plane and an energy
range from ∼0.3 to 80 keV/e, from which the distribution functions
of suprathermal ions, including those ions created in pick-up and
local shock acceleration processes, are also provided.
Title: Whole Heliosphere Interval: Early Science Results
Authors: Gibson, Sarah; Webb, David; Thompson, Barbara
Bibcode: 2008cosp...37.1011G
Altcode: 2008cosp.meet.1011G
The Whole Heliosphere Interval (WHI) is an international coordinated
observing and modeling effort to characterize the three-dimensional
interconnected solar-heliospheric-planetary system at solar minimum,
using observations originating at the Sun during Carrington Rotation
2067: March 20 - April 16, 2008. WHI's science begins with the solar
interior and extends through the heliosphere and interplanetary
space out to the heliopause. WHI is a special campaign period of the
International Heliophysical Year, and involves the participation of
many observatories and researchers around the world. A "synoptic" set
of observations provides baseline measurements of the heliophysical
system, while "targeted" observing campaigns during the WHI interval
focuses on particular sub-regions of the coupled heliospheric system
and address specific scientific questions via day-to-day coordinated
observations. This talk will showcase early results of the WHI
campaign, and thus provide a broad description of the heliosphere at
solar minimum.
Title: Multi-Spacecraft Observations of Recurring Proton Entropy
Enhancements Near Solar Minimum
Authors: Simunac, Kristin; Galvin, Antoinette; Kistler, Lynn;
Popecki, Mark; Moebius, Eberhard; Farrugia, Charles; Luhmann, Janet
G.; Russell, Christopher; Klecker, Berndt; Wimmer-Schweingruber,
Robert F.; Thompson, Barbara
Bibcode: 2008cosp...37.2908S
Altcode: 2008cosp.meet.2908S
The approach to solar minimum in 2007 was an exceptionally quiet time
in terms of solar activity. Recurring patterns of fast and slow solar
wind dominated the in situ observations, making it an ideal time to
study large-scale structures such as recurring high-speed streams
and co-rotating interaction regions. The leading and trailing edges
of high-speed streams can be identified in part through changes in
proton entropy. We have combined in situ data from STEREO-A, STEREO-B,
and WIND to study the geometry and evolution of recurring highspeed
streams that have enhanced entropy compared to slow, ambient solar
wind. Parkerspiral-like geometry is observed for both the leading and
trailing edges. The trailing edges are observed to have effective
speeds which are sometimes less than the solar wind bulk speed. We
will discuss the implications of these findings.
Title: Education and public outreach program for IHY A global
approach
Authors: Rabello-Soares, M. C.; Thompson, B. J.; Scherrer, D.;
Morrow, C.
Bibcode: 2008AdSpR..41.1206R
Altcode:
Education and public outreach (EPO) is one of the four components
of the International Heliophysical Year (IHY). It is fundamental in
achieving one of IHY’s primary objectives which is to “demonstrate
the beauty, relevance and significance of Space and Earth science
to the world.” In this paper we give an overview of the IHY EPO
Program. We describe its goals, structure, elements, plans and what
have already been achieved.
Title: IHY-IPY conference report from Polar Gateways Arctic Circle
Sunrise 2008
Authors: Cooper, John; Kauristie, Kirsti; Weatherwax, Allan; Thompson,
Barbara; Sheehan, Glenn; Smith, Roger; Sandahl, Ingrid
Bibcode: 2008cosp...37..581C
Altcode: 2008cosp.meet..581C
Polar, heliophysical, and planetary science topics related to the
International Heliophysical and Polar Years 2007-2009 were addressed
during this unique circumpolar conference hosted January 23-29,
2008 at the new Barrow Arctic Research Center of the Barrow Arctic
Science Consortium in Barrow, Alaska. Science presentations spanned
the solar system from the polar Sun and heliospheric environment to
Earth, Moon, Mars, Jupiter, Saturn, the Kuiper Belt, and the solar
wind termination shock now crossed by both Voyager spacecraft. Many of
the science presentations were made remotely via video conference or
teleconference from Sweden, Norway, Russia, Canada, Antarctica, and the
United States, spanning up to thirteen time zones (Alaska to Russia)
at various times during the conference. U.S. remote contributions came
from the University of Alaska at Fairbanks, the University of California
at Berkeley, the University of Arizona, NASA Jet Propulsion Laboratory,
and NASA Goddard Space Flight Center. Convening during the first week
of 2008 Arctic sunrise at Barrow, this conference served as a prelude
that year to international Sun-Earth Day celebrations for IHY, while
also commemorating Barrow scientific and native cultural support for the
first International Polar Year 1882-1883. Extensive educational outreach
activities were conducted with the local Barrow and Alaska North Slope
communities and through the NASA Digital Learning Network live from the
"top of the world" at Barrow. The conference proceedings are Internet
accessible via the home page at http://polargateways2008.org/.
Title: Solar Wind and Suprathermal Ion Populations at the STEREO
Spacecraft Approaching Solar Minimum
Authors: Galvin, A. B.; Popecki, M.; Kistler, L.; Simunac, K.;
Farrugia, C.; Gustafson, A.; Barry, J.; Ellis, L.; Moebius, E.; Blush,
L.; Klecker, B.; Bochsler, P.; Wurz, P.; Wimmer-Schweingruber, R.;
Thompson, B.; Luhmann, J.; Russell, C.
Bibcode: 2007AGUFMSH33A1083G
Altcode:
The two STEREO spacecraft, which were launched in October 2006, have
been gradually separating in longitude at a rate of about 22 degrees
per year. During this past year, the dominant heliospheric features
have been a series of recurrent high and slow speed solar wind and
their interaction regions, an occasional transient event (e.g., May
22), and "background" suprathermal populations such as interstellar
pick up ions. In this poster we present an overview of the plasma
and suprathermal signatures observed by the STEREO spacecraft using
data from the Plasma and Suprathermal Ion Composition (PLASTIC)
and Magnetometer (IMPACT/MAG) investigations. Complementary STEREO
PLASTIC related presentations in this session are by Popecki et al.,
Klecker et al. (invited), and Simunac et al.
Title: Correction to ``Major geomagnetic storms (Dst <= -100 nT)
generated by corotating interaction regions''
Authors: Richardson, I. G.; Webb, D. F.; Zhang, J.; Berdichevsky,
D. B.; Biesecker, D. A.; Kasper, J. C.; Kataoka, R.; Steinberg, J. T.;
Thompson, B. J.; Wu, C. -C.; Zhukov, A. N.
Bibcode: 2007JGRA..11212105R
Altcode:
Abstract Available
from http://www.agu.org
Title: Pickup Helium in the Inner Heliosphere: an Overview
Authors: Klecker, B.; Galvin, A. B.; Kucharek, H.; Kistler, L. M.;
Popecki, M. A.; Mouikis, C.; Farrugia, C.; Möbius, E.; Lee,
M. A.; Ellis, L.; Simunac, K.; Singer, K.; Blush, L. M.; Bochsler,
P.; Wurz, P.; Daoudi, H.; Giammanco, C.; Karrer, R.; Opitz, A.;
Wimmer-Schweingruber, R. F.; Koeten, M.; Hilchenbach, M.; Thompson,
B.; Acuna, M.; Luhman, J.
Bibcode: 2007AGUFMSH51B..01K
Altcode:
The CELIAS experiment onboard SOHO and the two Plasma and Suprathermal
Ion Composition (PLASTIC) experiments onboard STEREO-A/B provide
measurements of velocity, mass and ionic charge of solar wind ions
and of suprathermal particles up to energies of 80 keV/e (PLASTIC)
and 600 keV/e (CELIAS), respectively. Thus both the SOHO and STEREO
instrumentation covers the energy range of the pickup He particle
population of interstellar origin that is accelerated to suprathermal
energies at interplanetary shocks and corotating interaction regions
(CIRs). ACE and SOHO observations showed a large variability of both
the pickup He source and the flux of suprathermal particles that so
far could not be satisfactorily explained. In this overview we will
summarize recent pickup He observations with ACE and SOHO at 1 AU,
present first results of pickup He in CIRs obtained with STEREO, and
discuss open questions that can be tackled in the near future with
the new constellation of several spacecraft in the inner heliosphere.
Title: Probing the 2-D Geometry of CIRs at Solar Minimum: Observations
From STEREO
Authors: Simunac, K. D.; Galvin, A. B.; Kistler, L. M.; Popecki,
M. A.; Farrugia, C.; Moebius, E.; Ellis, L.; Blush, L. M.; Bochsler,
P.; Wurz, P.; Klecker, B.; Wimmer-Schweingruber, R. F.; Thompson,
B. J.; Luhmann, J. G.; Russell, C. T.; Jian, L. K.
Bibcode: 2007AGUFMSH33A1084S
Altcode:
The twin STEREO observatories provide a unique opportunity to study
the two-dimensional in-ecliptic geometry of structures in the solar
wind. At the start of 2007 the AHEAD (A) and BEHIND (B) satellites
were near Earth. By the end of the year they will each be separated
from Earth by about 20 degrees longitudinally, and from each other
by about 40 degrees. This arrangement is well suited to test the
conceptual picture of CIRs in the ecliptic plane. The orbital radius
of STEREO A is about 0.98 AU, while STEREO B is at about 1.03 AU. If
A and B were at the same line of longitude they would be less than
2000 Earth radii apart. Observations show this small radial separation
becomes important when predicting the arrival time at Earth of streams
observed with STEREO B; stream fronts were seen to arrive at A and B
almost simultaneously in mid 2007 when the spacecraft were separated
by about 7 degrees. This suggests the leading edge of the stream is
roughly aligned with the solar wind garden hose angle. We report on
observations of the leading edges of co-rotating high-speed streams,
and discuss the implications for space weather forecasting.
Title: Correction to ``Solar and interplanetary sources of major
geomagnetic storms (Dst <= -100 nT) during 1996-2005''
Authors: Zhang, J.; Richardson, I. G.; Webb, D. F.; Gopalswamy, N.;
Huttunen, E.; Kasper, J.; Nitta, N. V.; Poomvises, W.; Thompson,
B. J.; Wu, C. -C.; Yashiro, S.; Zhukov, A. N.
Bibcode: 2007JGRA..11212103Z
Altcode:
Abstract Available
from http://www.agu.org
Title: Solar and interplanetary sources of major geomagnetic storms
(Dst <= -100 nT) during 1996-2005
Authors: Zhang, J.; Richardson, I. G.; Webb, D. F.; Gopalswamy, N.;
Huttunen, E.; Kasper, J. C.; Nitta, N. V.; Poomvises, W.; Thompson,
B. J.; Wu, C. -C.; Yashiro, S.; Zhukov, A. N.
Bibcode: 2007JGRA..11210102Z
Altcode:
We present the results of an investigation of the sequence of
events from the Sun to the Earth that ultimately led to the 88 major
geomagnetic storms (defined by minimum Dst ≤ -100 nT) that occurred
during 1996-2005. The results are achieved through cooperative
efforts that originated at the Living with a Star (LWS) Coordinated
Data-Analysis Workshop (CDAW) held at George Mason University in
March 2005. On the basis of careful examination of the complete array
of solar and in situ solar wind observations, we have identified
and characterized, for each major geomagnetic storm, the overall
solar-interplanetary (solar-IP) source type, the time, velocity, and
angular width of the source coronal mass ejection (CME), the type and
heliographic location of the solar source region, the structure of the
transient solar wind flow with the storm-driving component specified,
the arrival time of shock/disturbance, and the start and ending times
of the corresponding IP CME (ICME). The storm-driving component,
which possesses a prolonged and enhanced southward magnetic field
(Bs), may be an ICME, the sheath of shocked plasma (SH)
upstream of an ICME, a corotating interaction region (CIR), or a
combination of these structures. We classify the Solar-IP sources
into three broad types: (1) S-type, in which the storm is associated
with a single ICME and a single CME at the Sun; (2) M-type, in which
the storm is associated with a complex solar wind flow produced by
multiple interacting ICMEs arising from multiple halo CMEs launched
from the Sun in a short period; (3) C-type, in which the storm is
associated with a CIR formed at the leading edge of a high-speed stream
originating from a solar coronal hole (CH). For the 88 major storms,
the S-type, M-type, and C-type events number 53 (60%), 24 (27%), and 11
(13%), respectively. For the 85 events for which the surface source
regions could be investigated, 54 (63%) of the storms originated in
solar active regions, 11 (13%) in quiet Sun regions associated with
quiescent filaments or filament channels, and 11 (13%) were associated
with coronal holes. Remarkably, nine (11%) CME-driven events showed no
sign of eruptive features on the surface or in the low corona (e.g.,
no flare, no coronal dimming, and no loop arcade, etc.), even though
all the available solar observations in a suitable time period were
carefully examined. Thus while it is generally true that a major
geomagnetic storm is more likely to be driven by a frontside fast
halo CME associated with a major flare, our study indicates a broad
distribution of source properties. The implications of the results
for space weather forecasting are briefly discussed.
Title: HiRISE Observations of Valles Marineris Layering
Authors: Beyer, R. A.; Weitz, C. M.; Thompson, B. J.; Moore, J. M.;
McEwen, A. S.; HiRISE Team
Bibcode: 2007LPICo1353.3310B
Altcode:
We used HiRISE to examine layering in the chasma slopes, the interior
mesas, the chasma floors, and layers observed on the surrounding
plains. Images show extensive layering with variable lithologies,
and stunning new views of familiar landscapes.
Title: Bulk Properties of Solar Wind Protons: Inter-comparison of
Observations From STEREO, SOHO, ACE, and WIND
Authors: Simunac, K. D.; Galvin, A. B.; Kistler, L. A.; Popecki, M. A.;
Farrugia, C.; Moebius, E.; Lee, M.; Ellis, L.; Singer, K.; Walker,
C.; Blush, L. M.; Bochsler, P.; Wurz, P.; Daoudi, H.; Giammanco,
C.; Karrer, R.; Opitz, A.; Klecker, B.; Wimmer-Schweingruber, R. F.;
Koeten, M.; Thompson, B.
Bibcode: 2007AGUSMSH41A..10S
Altcode:
The twin STEREO observatories were launched in October 2006. The PLASTIC
experiment onboard both spacecraft analyzes ions with energies between
0.25 and 80 keV/charge, including solar wind protons. Information on
bulk properties such as density, speed, and temperature are obtained. In
early 2007 STEREO A was separated from SOHO, ACE, WIND, and STEREO
B by hundreds of earth radii within the ecliptic plane, and by tens
of earth radii out of the ecliptic plane. We report on comparisons of
bulk parameters between these spacecraft, and what they show us about
small-scale temporal and spatial variations in the solar wind.
Title: Early Results from STEREO SECCHI COR1
Authors: St. Cyr, Orville C.; Davila, J. M.; Thompson, W.; Thompson,
B. J.; Gurman, J. B.; Burkepile, J. T.; de Toma, G.
Bibcode: 2007AAS...21011903S
Altcode: 2007BAAS...39..243S
With the successful launch and commissioning of STEREO, routine
observations of the Sun's corona by the payload began in early 2007. The
COR1 internally-occulted coronagraphs, which are classically-designed
Lyot instruments covering 1.4-4.0 Rsun, are performing extremely
well. More than two dozen coronal mass ejections (CMEs) were detected
by COR1 in the first month of observations. As the STEREO spacecraft
separate away from Earth, the MK4 coronameter at MLSO will provide
a third vantage point for observations of the low corona. In this
presentation we will show CME observations from COR1 and MK4, and we
will describe the context of these new observations.
Title: IHY - An International Cooperative Program
Authors: Rabello-Soares, M. Cristina; Davila, J.; Gopalswamy, N.;
Thompson, B.
Bibcode: 2007AAS...210.5701R
Altcode: 2007BAAS...39..167R
The International Heliophysical Year (IHY) in 2007/2008 involves
thousands of scientists representing over 70 nations. It consists
of four distinct elements that will be described here. Taking
advantage of the large amount of heliophysical data acquired routinely
by a vast number of sophisticated instruments aboard space missions and
at ground-based observatories, IHY aims to develop the basic science of
heliophysics through cross-disciplinary studies of universal processes
by means of Coordinated Investigation Programs (CIPs). The second
component is in collaboration with the United Nations Basic Space
Science Initiative (UNBSSI) and consists of the deployment of arrays of
small, inexpensive instruments such as magnetometers, radio antennas,
GPS receivers, etc. around the world to provide global measurements. An
important aspect of this partnership is to foster the participation
of developing nations in heliophysics research. IHY coincides
with the commemoration of 50 years of the space age that started with
launch of Sputnik on October 4, 1957 and it is on the brink of a new
age of space exploration where the Moon, Mars and the outer planets
will be the focus of the space programs in the next years. As a result,
it presents an excellent opportunity to create interest for science
among young people with the excitement of discovery of space. The
education and outreach program forms another cornerstone of IHY. Last but not least, an important part of the IHY activities, its
forth component, is to preserve the history and memory of IGY 1957.
Title: Observations of Energetic O+ in the Distant Tail Magnetosheath:
Results from STEREO/PLASTIC
Authors: Kistler, L. M.; Galvin, A. B.; Popecki, M. A.; Mouikis,
C.; Farrugia, C.; Moebius, E.; Lee, M. A.; Ellis, L.; Simunac, K.;
Singer, K.; Blush, L. M.; Klecker, B.; Wimmer-Schweingruber, R. F.;
Thompson, B.; Bochsler, P.; Wurz, P.; Karrer, R.; Opitz, A.; Luhmann,
J.; Acuna, M.; Russell, C. T.
Bibcode: 2007AGUSMSH34A..03K
Altcode:
Two identical Plasma and Suprathermal Ion Composition (PLASTIC)
instruments are now flying on the STEREO A and B observatories, which
launched in October 2006. PLASTIC is a solar wind and heliospheric
ion mass spectrometer that utilizes electrostatic deflection,
post-acceleration,time-of-flight, energy, and position measurements
in the energy-per-charge range of 0.25-80 keV/e. During the month
of February, 2007, as the spacecraft were approaching their final
heliocentric orbits, STEREO B traversed the dusk-side magnetosheath and
boundary layer from -100 Re to -300 Re down the tail. Throughout the
month, bursts of energetic O+ were observed in the magnetosheath. The
energy of the O+ extended to the upper range of the instrument, 80
keV. The occurrence of O+ correlated with periods of high solar wind
velocity. We will compare these observations with observations of O+
in the near-earth magnetosheath, as observed by CLUSTER, and discuss
the possible sources and transport paths for these ions.
Title: On the Variability of Suprathermal He+: new Results From
STEREO and SOHO
Authors: Klecker, B.; Galvin, A. B.; Kistler, L. M.; Popecki, M. A.;
Mouikis, C.; Farrugia, C.; Moebius, E.; Lee, M.; Ellis, L.; Simunac,
K.; Singer, K.; Blush, L. M.; Bochsler, P.; Wurz, P.; Daoudi, H.;
Giammanco, C.; Karrer, R.; Opitz, A.; Wimmer-Schweingruber, R. F.;
Koeten, M.; Hilchenbach, M.; Thompson, B.; Acuna, M.; Luhmann, J.
Bibcode: 2007AGUSMSH34A..02K
Altcode:
The two Plasma and Suprathermal Ion Composition (PLASTIC) experiments
onboard STEREO-A and STEREO-B and the CELIAS experiment onboard SOHO
provide measurements of velocity, mass and ionic charge of solar
wind ions and of suprathermal particles up to energies of 80 keV/e
(PLASTIC) and 600 keV/e (CELIAS), respectively. The observations with
SOHO showed a large variability of the He+/He2+ -ratio at suprathermal
energies, with He+/He2+ > 1 in many interplanetary shock related
solar energetic particle (SEP) events. This variability is much
larger than the observed variations in the interstellar pickup He+
source and suggests that the different velocity distributions of
the two sources, i.e. solar wind and pickup ions of interstellar
origin, play an important role for the efficiency of injection and/or
acceleration of these ions. Thus PLASTIC onboard STEREO, covering the
energy range from solar wind to pickup ion and suprathermal energies,
has the potential for resolving some of the questions related to the
large variability of the He+/He2+-ratios. In this paper we will review
the SOHO measurements of pickup and suprathermal He+ ions at 1 AU, show
first results from PLASTIC onboard STEREO and discuss the perspective
to tackle some of the open questions.
Title: Early Solar Wind Observations from the Plasma and Suprathermal
Ion Composition (PLASTIC) Experiments on STEREO
Authors: Galvin, A. B.; Kistler, L. A.; Popecki, M. A.; Farrugia, C.;
Moebius, E.; Lee, M.; Ellis, L.; Simunac, K.; Singer, K.; Russell,
C.; Walker, C.; Blush, L.; Klecker, B.; Wimmer-Schweingruber, R. F.;
Thompson, B.; Bochsler, P.; Wurz, P.; Daoudi, H.; Giammanco, C.;
Karrer, R.; Opitz, A.; Koeten, M.; Luhmann, J.; Howard, R.; Wuelser,
J. P.; Acuna, M.
Bibcode: 2007AGUSMSH34A..01G
Altcode:
Two identical Plasma and Suprathermal Ion Composition (PLASTIC)
instruments are now flying on the STEREO A and B observatories, which
launched in October 2006. The STEREO observatories are drifting away
from the Earth and from each other, providing different longitudinal
perspectives. PLASTIC together with the IMPACT suite provides the
in-situ measurements for the STEREO mission, while SECCHI provides
remote imaging of the solar corona. The PLASTIC solar wind sector
measures solar wind proton bulk parameters and provides species
identification and relative abundances for the more dominant solar wind
minor (Z>2) ions. During this early part of the STEREO mission,
as we approach solar minimum conditions, there have been a series of
coronal- hole associated high speed streams and interstream sector
boundaries. In this talk we will provide initial observations of the
solar wind during selected time periods.
Title: International Heliophysical Year 2007: Basic space science
initiatives
Authors: Davila, Joe; Gopalswamy, Nat; Haubold, Hans J.; Thompson,
Barbara
Bibcode: 2007SpPol..23..121D
Altcode:
The UN Office for Outer Space Affairs, through the IHY Secretariat
and the United Nations Basic Space Science Initiative (UNBSSI),
assists scientists and engineers world-wide to participate in
the International Heliophysical Year (IHY) 2007. A major thrust of
IHY/UNBSSI is to deploy arrays of small, inexpensive instruments such
as magnetometers, radio telescopes, GPS receivers, all-sky cameras,
etc. around the world to allow global measurements of ionospheric and
heliospheric phenomena. The small instrument program is envisioned
as a partnership between instrument providers and instrument hosts
in developing nations, with the former providing the instruments,
the host nation the manpower, facilities and operational support,
typically at a local university. Funds are not available through
IHY/UNBSSI to build the instruments; these must be obtained through the
normal proposal channels. All instrument operational support for local
scientists, facilities, data acquisition, etc. will be provided by the
host nation. The IHY/UNBSSI can facilitate the deployment of several
of these networks and existing databases and relevant software tools
will be identified to promote space science activities in developing
nations. Extensive data on space science have been accumulated
by a number of space missions. Similarly, long-term databases are
available from ground-based observations. These data can be utilized
in ways different from those originally intended for understanding the
heliophysical processes. This report provides an overview of IHY/UNBSSI,
its achievements, future plans and outreach to the 192 member states
of the United Nations.
Title: Globalizing space and Earth science - the International
Heliophysical Year Education and Outreach Programme
Authors: Rabello-Soares, M. Cristina; Morrow, Cherilynn; Thompson,
Barbara; Webb, David
Bibcode: 2007IAUSS...5..289R
Altcode:
No abstract at ADS
Title: The United Nations Basic Space Science Initiative for IHY 2007
Authors: Gopalswamy, Nat; Davila, Joseph; Thompson, Barbara; Haubold,
Hans
Bibcode: 2007IAUSS...5..295G
Altcode:
No abstract at ADS
Title: The United Nations Basic Space Science Initiative: the
TRIPOD concept
Authors: Kitamura, Masatoshi; Wentzel, Don; Henden, Arne; Bennett,
Jeffrey; Al-Naimiy, H. M. K.; Mathai, A. M.; Gopalswamy, Nat; Davila,
Joseph; Thompson, Barbara; Webb, David; Haubold, Hans
Bibcode: 2007IAUSS...5..277K
Altcode: 2006physics..10149K
Since 1990, the United Nations is annually holding a workshop on
basic space science for the benefit of the worldwide development of
astronomy. Additional to the scientific benefits of the workshops and
the strengthening of international cooperation, the workshops lead to
the establishment of astronomical telescope facilities through the
Official Development Assistance (ODA) of Japan. Teaching material,
hands-on astrophysics material, and variable star observing programmes
had been developed for the operation of such astronomical telescope
facilities in an university environment. This approach to astronomical
telescope facility, observing programme, and teaching astronomy has
become known as the basic space science TRIPOD concept. Currently,
a similar TRIPOD concept is being developed for the International
Heliophysical Year 2007, consisting of an instrument array, data taking
and analysis, and teaching space science.
Title: The International Heliophysical Year
Authors: Davila, Joseph M.; Gopalswamy, Nat; Thompson, Barbara J.
Bibcode: 2007RoAJ...17....3D
Altcode:
No abstract at ADS
Title: Three-dimensional global simulation of multiple ICMEs’
interaction and propagation from the Sun to the heliosphere following
the 25 28 October 2003 solar events
Authors: Wu, C. -C.; Fry, C. D.; Dryer, M.; Wu, S. T.; Thompson, B.;
Liou, Kan; Feng, X. S.
Bibcode: 2007AdSpR..40.1827W
Altcode:
This study performs simulations of interplanetary coronal mass
ejection (ICME) propagation in a realistic three-dimensional
(3D) solar wind structure from the Sun to the Earth by using the
newly developed hybrid code, HAFv.2+3DMHD. This model combines
two simulation codes, Hakamada-Akasofu-Fry code version 2 (HAFv.2)
and a fully 3D, time-dependent MHD simulation code. The solar wind
structure is simulated out to 0.08 AU (18 Rs) from source surface
maps using the HAFv.2 code. The outputs at 0.08 AU are then used to
provide inputs for the lower boundary, at that location, of the 3D MHD
code to calculate solar wind and its evolution to 1 AU and beyond. A
dynamic disturbance, mimicking a particular flare's energy output,
is delivered to this non-uniform structure to model the evolution
and interplanetary propagation of ICMEs (including their shocks). We
then show the interaction between two ICMEs and the dynamic process
during the overtaking of one shock by the other. The results show that
both CMEs and heliosphere current sheet/plasma sheet were deformed by
interacting with each other.
Title: Duplicity in 16 Piscium Confirmed from Its Occultation by 7
Iris on 2006 May 5
Authors: Thompson, B.; Yeelin, T.
Bibcode: 2006PASP..118.1648T
Altcode:
The occultation of 16 Piscium by the asteroid 7 Iris on 2006 May 5 was
observed with a mobile telescope at a site near Ithaca, New York. The
signal from a video camera was time-stamped and recorded. Computer
analysis of the recording shows a stepped disappearance and
reappearance, as is expected for a double star. After correcting for
saturated pixels in the recording, the two components of the double star
were determined to have nearly equal magnitudes. By assuming a circular
silhouette for the asteroid, the separation and position angle of the
double star is constrained to two possibilities. This occultation result
confirms a previous spectroscopic observation by G. Cayrel de Strobel.
Title: IHY-CAWSES Data base
Authors: Young, C. A.; Thompson, B. J.; Davila, J.; Gopalswamy, N.
Bibcode: 2006ihy..workE..90Y
Altcode:
In partnership with the CAWSES (Climate And Weather of the Sun-Earth
System) program, IHY is sponsoring a series of Virtual Workshops
and a special IHY/CAWSES database to provide virtual access of data
collected for IHY and CAWSES campaigns. The first of the virtual
workshops occurred November 13-17, 2006, and had more than 200 online
participants. Online presentation and discussion tools are being
refined for future workshops. The IHY/CAWSES database provides a means
of entering data into the Virtual Solar Observatory (to provide the
maximum and easiest possible access to the data) while still maintaining
a close connection to the other data sets used in IHY/CAWSES activities.
Title: IHY-2007: Coordinated Investigation Programs (CIPs)
Authors: Thompson, B. J.; et al.
Bibcode: 2006ihy..workE..17T
Altcode:
The IHY has established a set of primary scientific objectives
and goals. To accomplish these goals, a wide range of Coordinated
Investigation Programs (CIPs) will transpire throughout the
IHY timeframe, driving towards a more complete understanding of
heliophysical universal processes. The CIPs are the basic "building
block" of IHY science - they are proposed by members of the IHY
community, and are approved and coordinated by the IHY discipline
coordinators. The aim is that the program remains under the control
of the proposer(s) with the IHY CIP process providing a means of
publicising the proposed work, co-ordinating access to and use of the
necessary resources, and a forum for discussing the results. There
are currently over 50 CIPs in the IHY database, with many more being
proposed.
Title: IHY/UNBSS Program: Success Stories
Authors: Gopalswamy, N.; Davila, J.; Thompson, B. J.; Haubold, H. J.
Bibcode: 2006ihy..workE..15G
Altcode:
The United Nations Office for Outer Space Affairs, through the IHY
secretariat and the United Nations Basic Space Science Initiative
(UNBSSI) is assisting scientists and engineers from all over the world
in participating in the International Heliophysical Year (IHY) 2007. A
major thrust of the IHY/UNBSSI program is to deploy arrays of small,
inexpensive instruments such as magnetometers, radio telescopes, GPS
receivers, etc. around the world to provide global measurements of
ionospheric and heliospheric phenomena. The small instrument program
is a partnership between instrument providers, and instrument hosts in
developing countries. The lead scientist will provide the instruments
(or fabrication plans for instruments) in the array; the host country
will provide manpower, facilities, and operational support to obtain
data with the instrument typically at a local university. Existing data
bases and relevant software tools can be identified to promote space
science activities in developing countries. Extensive data on space
science have been accumulated by a number of space missions. Similarly,
long-term data bases are available from ground based observations. These
data can be utilized in ways different from originally intended for
understanding the heliophysical processes. This paper provides an
overview of the IHY/UNBSS program, its achievements and future plans.
Title: Globalizing Space and Earth Science - the International
Heliophysical Year Education and Outreach Program
Authors: Rabello-Soares, M. C.; Morrow, C.; Thompson, B. J.
Bibcode: 2006IAUSS...5E..48R
Altcode:
The International Heliophysical Year (IHY) in 2007 & 2008 will
celebrate the 50th anniversary of the International Geophysical
Year (IGY) and, following its tradition of international research
collaboration, will focus on the cross-disciplinary studies of
universal processes in the heliosphere. The main goal of IHY Education
and Outreach Program is to create more global access to exemplary
resources in space and earth science education and public outreach. By
taking advantage of the IHY organization with representatives in
every nation and in the partnership with the United Nations Basic
Space Science Initiative (UNBSSI), we aim to promote new international
partnerships. Our goal is to assist in increasing the visibility and
accessibility of exemplary programs and in the identification of formal
or informal educational products that would be beneficial to improve the
space and earth science knowledge in a given country; leaving a legacy
of enhanced global access to resources and of world-wide connectivity
between those engaged in education and public outreach efforts that are
related to IHY science. Here we describe how to participate in the IHY
Education and Outreach Program and the benefits in doing so. Emphasis
will be given to the role played by developing countries; not only
in selecting useful resources and helping in their translation and
adaptation, but also in providing different approaches and techniques
in teaching.
Title: The United Nations Basic Space Science Initiative for IHY 2007
Authors: Gopalswamy, N.; Davila, J. M.; Thompson, B. J.; Haubold, H.
Bibcode: 2006IAUSS...5E..47G
Altcode:
The United Nations, in cooperation with national and international
space-related agencies and organizations, has been organizing annual
workshops since 1990 on basic space science, particularly for the
benefit of scientists and engineers from developing nations. The United
Nations Office for Outer Space Affairs, through the IHY Secretariat and
the United Nations Basic Space Science Initiative (UNBSSI) will assist
scientists and engineers from all over the world in participating in
the International Heliophysical Year (IHY) 2007. A major thrust of the
IHY/UNBSSI program is to deploy arrays of small, inexpensive instruments
such as magnetometers, radio telescopes, GPS receivers, all-sky cameras,
etc. around the world to provide global measurements of ionospheric
and heliospheric phenomena. The small instrument program is envisioned
as a partnership between instrument providers, and instrument hosts in
developing countries. The lead scientist will provide the instruments
(or fabrication plans for instruments) in the array; the host country
will provide manpower, facilities, and operational support to obtain
data with the instrument typically at a local university. Funds
are not available through the IHY to build the instruments; these
must be obtained through the normal proposal channels. However all
instrument operational support for local scientists, facilities, data
acquisition, etc will be provided by the host nation. It is our hope
that the IHY/UNBSSI program can facilitate the deployment of several of
these networks world wide. Existing data bases and relevant software
tools that can will be identified to promote space science activities
in developing countries. Extensive data on space science have been
accumulated by a number of space missions. Similarly, long-term data
bases are available from ground based observations. These data can be
utilized in ways different from originally intended for understanding
the heliophysical processes. This paper provides an overview of the
IHY/UNBSS program, its achievements and future plans.
Title: Major geomagnetic storms (Dst <= -100 nT) generated by
corotating interaction regions
Authors: Richardson, I. G.; Webb, D. F.; Zhang, J.; Berdichevsky,
D. B.; Biesecker, D. A.; Kasper, J. C.; Kataoka, R.; Steinberg, J. T.;
Thompson, B. J.; Wu, C. -C.; Zhukov, A. N.
Bibcode: 2006JGRA..111.7S09R
Altcode: 2006JGRA..11107S09R
Seventy-nine major geomagnetic storms (minimum Dst ≤ -100 nT) observed
in 1996 to 2004 were the focus of a "Living with a Star" Coordinated
Data Analysis Workshop (CDAW) in March 2005. In nine cases, the storm
driver appears to have been purely a corotating interaction region (CIR)
without any contribution from coronal mass ejection-related material
(interplanetary coronal mass ejections (ICMEs)). These storms were
generated by structures within CIRs located both before and/or after the
stream interface that included persistently southward magnetic fields
for intervals of several hours. We compare their geomagnetic effects
with those of 159 CIRs observed during 1996-2005. The major storms form
the extreme tail of a continuous distribution of CIR geoeffectiveness
which peaks at Dst ∼ -40 nT but is subject to a prominent seasonal
variation of ∼40 nT which is ordered by the spring and fall equinoxes
and the solar wind magnetic field direction toward or away from the
Sun. The O'Brien and McPherron (2000) equations, which estimate Dst by
integrating the incident solar wind electric field and incorporating
a ring current loss term, largely account for the variation in storm
size. They tend to underestimate the size of the larger CIR-associated
storms by Dst ∼ 20 nT. This suggests that injection into the ring
current may be more efficient than expected in such storms. Four of
the nine major storms in 1996-2004 occurred during a period of less
than three solar rotations in September to November 2002, also the
time of maximum mean IMF and solar magnetic field intensity during
the current solar cycle. The maximum CIR-storm strength found in our
sample of events, plus additional 23 probable CIR-associated Dst ≤
-100 nT storms in 1972-1995, is (Dst = -161 nT). This is consistent
with the maximum storm strength (Dst ∼ -180 nT) expected from the
O'Brien and McPherron equations for the typical range of solar wind
electric fields associated with CIRs. This suggests that CIRs alone
are unlikely to generate geomagnetic storms that exceed these levels.
Title: A Kopp-Pneuman-like Picture of Coronal Mass Ejections
Authors: Spicer, D. S.; Sibeck, D.; Thompson, B. J.; Davila, J. M.
Bibcode: 2006ApJ...643.1304S
Altcode:
A new coronal mass ejection (CME) picture is described that utilizes
a number of attributes commonly found operating during magnetotail
reconnection events. We first present key observational constraints any
final model of CMEs must explain. We then describe how three-dimensional
reconnection occurs in the magnetotail and how magnetotail reconnection
helps explain a variety of observed CME attributes. We then argue why
reconnection, as usually described in the literature, cannot explain
the particle acceleration process that occurs during the CME/flare
process. Instead we argue that it is the flow fields that are driven
by the relaxation of the magnetic stresses due to reconnection that
are ultimately the cause of particle acceleration. In particular, it
is the electrons that make up the discharging field-aligned currents,
which connect flow field-driven cross field inertial currents in the
high corona with the chromosphere, that are in fact the high-energy
electrons needed to explain flare ribbons and other high-energy
emissions. We compute the expected electron fluxes from these current
systems and find that they are of order those required. In addition,
we discuss betatron acceleration during the dipolarization process
that occurs when the flux rope/CME is ejected and how the hot particles
generated during the dipolarization process can lead to traps in solar
loops, thereby helping to explain long-duration events. Further, we
examine whether particle acceleration by shocks can contribute to the
mix. We also note that our new picture eliminates a number of paradoxes,
specifically elimination of magnetic flux from the Sun and how the Aly
conjecture is not of consequence in our picture. Finally, we examine
what will be needed to numerically simulate our picture of a CME.
Title: Major geomagnetic storms (Dst≤-100~nT) generated by
corotating interaction regions in 1996--2004
Authors: Richardson, I. G.; Webb, D. F.; Zhang, J.; Berdichevsky,
D. B.; Biesecker, D. A.; Kasper, J. C.; Kataoka, R.; Steinberg, J. T.;
Thompson, B. J.; Wu, C.; Zhukov, A. N.
Bibcode: 2006AGUSMSH53A..06R
Altcode:
Nine of the major geomagnetic storms (Dst≤-100~nT) in 1996 to 2004
studied at the "Living with a Star" CDAW workshop in March, 2005 were
driven purely by a corotating interaction region (CIR) without any
contribution from coronal mass ejection-related material. These storms
were generated by structures located both before and/or after the stream
interface that included persistently southward magnetic fields for
intervals of several hours. We compare the geomagnetic effects of these
storms with those of 159 CIRs observed during 1996 -- 2005. The major
storms form the extreme tail of a distribution of CIR geoeffectiveness
which peaks at Dst~-40~nT but has a prominent seasonal variation of
~40~nT ordered by the spring and fall equinoxes and the solar wind
magnetic field direction towards or away from the Sun. The O'Brien
and McPherron [2000] equations for Dst prediction largely account for
the variation in storm size but tend to underestimate the size of the
larger CIR-associated storms by Dst~20~nT, suggesting that injection
into the ring current may be more efficient than expected in such
storms. The maximum storm strength in these events, plus an additional
23 CIR-associated storms in 1972 -- 1995, is Dst=-161~nT. This is
consistent with the maximum storm strength (Dst~-180~nT) expected
for the range of solar wind electric fields associated with CIRs,
suggesting that CIRs alone are unlikely to generate geomagnetic storms
that exceed such levels.
Title: The IGY Gold History Preservation Program
Authors: Thompson, B. J.; Cliver, E. W.; Gentile, L. C.; Sigsbee,
K. M.; Doel, R. E.
Bibcode: 2006AGUSM.U41D..08T
Altcode:
An important part of the 2007 International Year activities will be
preserving the history and memory of IGY 1957. The "IGY Gold" History
initiative has several goals: 1) identifying and recognizing planners
of and participants in the first IGY, 2) preserving memoirs, articles,
photographs, and all items of historical significance for the IGY,
3) making these items available to historians, researchers, etc.,
4) serving as a contact service for these activities, 5) spreading
awareness of the history of geophysics, and 6) planning special events
and "reunions." The IGY "Gold" Club identifies participants from
the first IGY (gold symbolizing the 50th anniversary). "Gold club"
participants will be rewarded with a special "IGY Gold Anniversary"
certificate of recognition and a special commemorative "IGY Gold"
lapel pin. Many IGY participants from around the globe have received
IGY Gold Club awards, and many have submitted valuable historical
material about the IGY activities. This is a joint program of the IHY,
eGY, IPY, IYPE and IUGG.
Title: Planning the International Heliophysical Year (IHY)
Authors: Davila, Joseph M.; Thompson, Barbara J.; Gopalswamy, Nat
Bibcode: 2006UNPSA..17...37D
Altcode:
No abstract at ADS
Title: Preparing for the International Heliophysical Year (IHY) 2007
Authors: Davila, J. M.; Gopalswamy, N.; Thompson, B. J.
Bibcode: 2006ilws.conf..231D
Altcode:
The International Geophysical Year (IGY) of 1957, a broad-based and
all-encompassing effort to push the frontiers of geophysics, resulted
in a tremendous increase of knowledge in space physics, Sun-Earth
Connection, planetary science and the heliosphere in general. Now, 50
years later, we have the unique opportunity to advance our knowledge of
the global heliosphere and its interaction with planetary bodies and
the interstellar medium through the International Heliophysical Year
(IHY) in 2007. This will be an international effort, which will raise
public awareness of space physics.
Title: The IHY/United Nations Distributed Observatory Development
Program
Authors: Haubold, H.; Thompson, B. J.; Al-Naimiy, H.; Davila, J. M.;
Gopalswamy, N.; Groves, K.; Scherrer, D.
Bibcode: 2006cosp...36.3304H
Altcode: 2006cosp.meet.3304H
A major thrust of the International Heliophysical Year IHY is to
deploy arrays of small inexpensive instruments such as magnetometers
radio antennas GPS receivers all-sky cameras etc around the world
to provide global measurements of ionospheric magnetospheric and
heliospheric phenomena This program is a collaboration between the IHY
and the United Nations Basic Space Science Initiative UNBSSI which has
been dedicated to the IHY through 2009 The small instrument program
consists of a partnership between instrument providers and instrument
host countries The lead scientist provides the instrumentation or
fabrication plans for instruments in the array the host country
provides manpower facilities and operational support to obtain data
with the instrument typically at a local university This program has
been active in deploying instrumentation developing plans for new
instrumentation and identifying educational opportunities for the host
nations in association with this program We will discuss the program
s status significant deployment activities and plans for 2007-2009
Title: Understanding the Heliospheric Environment for NASA's
Spacefleet
Authors: St. Cyr, O. C.; Thompson, B. J.; Rowland, D. E.; Hesse, M.
Bibcode: 2006cosp...36.3297S
Altcode: 2006cosp.meet.3297S
Presently the U S National Aeronautics and Space Administration has more
than 50 active robotic science satellites seven active communications
satellites and the manned International Space Station With this
investment NASA has a responsibility to protect its space assets
throughout the solar system For humans this function is performed by
the Space Radiation Analysis Group at Johnson Space Center in Houston
Texas But for robotic explorers this function is performed only on
an ad hoc basis Space environmental awareness is missing for much of
the existing fleet beyond Earth-orbit and it is required for anomaly
resolution and good stewardship of our national assets Engineers
require this information to make a complete assessment of the root
cause of operational anomalies Threats to space assets arise from many
sources on a wide range of timescales direct effects of radiation and
energetic particles on robotic and human explorers indirect and delayed
effects on the heliosphere e g MHD shocks on planetary magnetospheres e
g transient radiation belts and on atmospheres e g aerobraking and long
term solar cycle predictions Because environmental assessment throughout
the heliosphere is not yet operational it requires interpretation of
data heterogeneous in form and quality groundbased and spacebased as
well as interaction with sophisticated numerical models A conceptual
study of environmental conditions was done on an ad hoc basis for
a failure at Mars in 2004 Here we will describe recent efforts and
discuss near-term plans at
Title: Outreach and Education Program for IHY - A Global Approach
Authors: Rabello-Soares, M. C.; Thompson, B. J.
Bibcode: 2006cosp...36.2631R
Altcode: 2006cosp.meet.2631R
The IHY Outreach and Education Program is one of the 4 main components
of IHY Science Observatory Development Outreach and History and it is
fundamental in achieving one of IHY s primary objectives which is to
demonstrate the beauty relevance and significance of Space and Earth
Science to the world The Outreach and Education Program for IHY has the
following objectives 1 inspire the next generation of Space and Earth
scientists and explorers and 2 spread the knowledge of our solar system
and the exciting process of scientific exploration to the public There
is already in place a wide variety of outreach and education activities
related to Space and Earth Science We would like to see all of them
come together to celebrate the International Heliophysical Year in 2007
The IHY Outreach and Education Program will focus on a developing new
and exciting outreach programs that provide unique opportunities for
the global community b increasing the visibility and accessibility of
existing outreach programs c developing partnerships between existing
programs and activities to broaden their scope and impact d determining
the need for
Title: International coordinated efforts for IHY 2007
Authors: Gopalswamy, N.; Davila, J.; Thompson, B.
Bibcode: 2006cosp...36.2743G
Altcode: 2006cosp.meet.2743G
The International Heliophysical Year IHY in 2007 marks the enormous
progress made since the International Geophysical Year IGY in 1957
The philosophy behind IHY is similar to that of IGY in studying the
environment of our habitat except that the scope has increased to the
physical space extending to the interstellar medium This paper describes
the international organization of the IHY and planning for a successful
program in 2007 In particular we describe the national regional and
global efforts in pooling the resources to address the universal
processes that govern the solar system and its interaction with the
surrounding medium The efforts include identifying science questions of
immediate concern and the data sets needed to address these questions
The data will be acquired using a truly distributed observatory
consisting of all the ground and space-based instruments that exist
today and those to be constructed before 2007 The international planning
also involves coordinating with the United Nations which through its
Basic Space Science Initiative is facilitating the participation of the
developing nations in the IHY program An update of the current status
of the planning activities at the international level will be presented
Title: The evolution and interaction of multiple coronal mass
Authors: Wu, C. C.; Fry, C.; Wu, S. T.; Dryer, M.; Thompson, B.;
Liou, K.; Feng, X. S.
Bibcode: 2006cosp...36..407W
Altcode: 2006cosp.meet..407W
The famous solar events of Halloween 2003 caused two of the most intense
geomagnetic storms with Dst min -363 and -401 nT during Solar Cycle
23 In order to understand the interplanetary causes of this famous
event which contains multiple flares and coronal mass ejections we
will perform MHD simulations to investigate the evolution of solar
disturbances that caused these severe geomagnetic storms This study
performs simulations of interplanetary coronal mass ejection ICME
propagation in a realistic 3D solar wind structure from the Sun to the
Earth by using the newly developed hybrid code HAFv 2 3DMHD This code
combines two simulation codes Hakamada-Akasofu-Fry code HAF version 2
HAFv 2 and a fully three-dimensional time-dependent MHD simulation code
and is used for this purpose The solar wind structure is simulated out
to 0 08 AU 18 solar radius from source surface maps 2 5 solar radii Rs
that are derived from daily-provided solar magnetograms using the HAFv 2
code This code is then used from 2 5 Rs to provide input for the lower
boundary of the 3D MHD code to calculate the evolution of solar wind
plasma and interplanetary magnetic field beyond 18 Rs 0 08 AU A dynamic
disturbance mimicing a particular flare s energy output is delivered to
this non-uniform structure to model the evolution and interplanetary
propagation of coronal mass ejections ICME including their shocks We
also integrate the line-of-sight density in the plane-of-sky to
Title: 2007: The International Heliophysical Year - a great
opportunity for Space and Earth Science outreach
Authors: Rabello-Soares, M. C.; Thompson, B. J.; Morrow, C.
Bibcode: 2006cosp...36.2649R
Altcode: 2006cosp.meet.2649R
Fifty years after the International Geophysical Year IGY in 1957 the
International Heliophysical Year IHY represents a logical next-step
extending the studies into the heliosphere and thus including
the drivers of geophysical change The IHY fields of research are
solar physics planetary magnetospheres heliosphere and cosmic rays
planetary ionospheres thermospheres and mesopheres climate studies
and heliobiology see session D1 2 The basic objectives of IHY are 1
advancing our understanding of the physical processes that govern the
Sun Earth and Heliosphere 2 continuing the tradition of international
research and advancing the legacy on the 50th anniversary of the
International Geophysical Year 3 demonstrating the Beauty Relevance
and Significance of Space and Earth Science to the World The IHY is
being coordinated by an international committee involving hundreds of
observatories and institutions worldwide The central coordination is
hosted by the American Geophysical Union Also the United Nations Basic
Space Science Initiative UNBSSI will dedicate its activities through
2009 to the IHY effort targeting activities in developing nations such
as the IHY UNBSSI Small Instrument Array Deployment
Title: The International Heliophysical Year (IHY) 2007
Authors: Davila, J. M.; Thompson, B. J.; Gopalswamy, N.
Bibcode: 2006AfrSk..10....4D
Altcode:
The International Geophysical Year (IGY) of 1957, a broad-based
and all-encompassing effort to push the frontiers of geophysics,
resulted in a tremendous increase of knowledge in space physics,
the Sun-Earth connection, planetary science, and the heliosphere in
general. Now, fifty years later, we have the unique opportunity to
advance our knowledge of the global heliosphere and its interaction with
planetary bodies and the interstellar medium through the International
Heliophysical Year (IHY) in 2007. This will be an international effort
which will raise public awareness of space physics. Because of its
unique geographic position, Africa is well-positioned to play a
critical role.
Title: Three-dimensional global simulation of CME/ICME/Shock
propagation from Sun to the heliosphere
Authors: Wu, C.; Fry, C.; Thompson, B. J.; Wu, S.; Dryer, M.; Liou, K.
Bibcode: 2005AGUFMSH14A..03W
Altcode:
This study performs simulations of the propagation of coronal mass
ejections from the Sun to the Earth through a realistic 3D solar
wind structure. The famous solar event of 12 May 1997, described
observationally by Thompson et al. [1998, 1999] and theoretically
by Wu et al. [2001], is used as motivation for this simulation. The
newly developed code, HAF+3DMHD combines two simulation codes,
Hakamada-Akasofu-Fry code (HAF) version 2 (HAFv.2) [Fry et al., 2001]
and a fully three-dimensional, time-dependent MHD simulation code
[Han et al, 1988]. The solar wind structure is simulated, using the
HAF code, out to 0.08 AU from source surface maps derived from solar
magnetograms. The HAF simulation is then used as input for the lower
boundary of a 3D MHD code to calculate the evolution of solar wind
plasma beyond 18 solar radii (0.08 AU). A dynamic disturbance is
delivered to this non-uniform structure to model the evolution and
interplanetary propagation of a coronal mass ejection (ICME, including
its shock). We also integrate the changing line-of-sight heliospheric
density to compare to data observed by the LASCO instrument on SOHO,
and we compare the derived ICME and shock structure at 1 AU to WIND
solar wind data for this 12 May 1997 event. This new code provides a
tool to link the general cases of ICME at 1 AU to their solar sources,
as well as to identify the possible origins of shock formation due to
CMEs and CME/CIR interactions. In the case of complex or interacting
ejecta, model interpretation is often required to accurately determine
the solar sources of the ejecta observed at 1 AU. Because this newly
developed model incorporates 3D MHD, its results can be extended to
simulate coronal and heliospheric observations, including the ambient
medium's non-uniformity provided by the HAFv.2 model, from the upcoming
STEREO mission. Reference: Fry et al., JGR, 106, 20985-21001, 2001. Han
et al., Comp. and Fluids, 16, 81-103, 1988. Thompson et al., GRL,
25, 2465-2468, 1998. Thompson et al., AP. J. Lett., 517, L151-L155,
1999. Wu et al., JGR, 106, 25089-25102, 2001.
Title: Distributed Instrumentation Deployment During the IHY
Authors: Davila, J. M.; Thompson, B. J.; Gopalswamy, N.
Bibcode: 2005AGUFMSM21A0347D
Altcode:
A major thrust of the International Heliophysical Year (IHY) is to
deploy arrays of small, inexpensive instruments such as magnetometers,
radio antennas, GPS receivers, all-sky cameras, etc. around the
world to provide global measurements of ionospheric and heliospheric
phenomena. This program is a collaboration between the IHY and the
United Nations Basic Space Science (UNBSS) program, which has been
dedicated to the IHY through 2009. The small instrument program is
envisioned as a partnership between instrument providers, and instrument
host countries. The lead scientist will provide the instruments (or
fabrication plans for instruments) in the array; the host country
will provide manpower, facilities, and operational support to obtain
data with the instrument typically at a local university. Instrument
operational support for local scientists, facilities, data acquisition,
etc will be provided by the host nation.
Title: Differentiating Between Streamer Deflections and "New Mass"
in Halo CMEs
Authors: Thompson, B. J.
Bibcode: 2005AGUFMSH13A0303T
Altcode:
The LASCO coronagraphs on board SOHO have detected hundreds of
halo coronal mass ejections, exhibiting a wide range of speeds and
propagation morphologies. However, it is important to distinguish which
aspects of the halo CME are due to erupting material, or "new mass," and
which aspects are due to the motion of pre-existing structures. We have
established a means of determining which aspects of halo CME emission
are due to newly added mass to the corona, and which aspects of halo
CME emission are due to the deflection of bright structures towards the
sky, thereby increasing their scattering efficiency. By mapping the CME
brightening into the pre-existing corona, it can be shown that some of
the emission in halo CMEs has a positive correlation with pre-event
features, which can only explained if we include the contribution of
streamer motion to the CME brightness. Differentiating between these two
sources of CME brightness (and apparent mass) is extremely important
because it allows better determination of the CME mass, morphology,
and direction of propagation, providing a better linkage to Earth. We
will discuss several events from different viewing angles, and will
suggest an algorithm that can be implemented in near-real time for
forecasting purposes.
Title: Sequential Chromospheric Brightenings beneath a Transequatorial
Halo Coronal Mass Ejection
Authors: Balasubramaniam, K. S.; Pevtsov, A. A.; Neidig, D. F.; Cliver,
E. W.; Thompson, B. J.; Young, C. A.; Martin, S. F.; Kiplinger, A.
Bibcode: 2005ApJ...630.1160B
Altcode:
Analyses of multiwavelength data sets for a solar eruption at ~21:30
UT on 2002 December 19 show evidence for the disappearance of a
large-scale, transequatorial coronal loop (TL). In addition, coronal
manifestations of the eruption (based on SOHO EIT and LASCO images)
include large-scale coronal dimming, flares in each associated active
region in the northern and southern hemispheres, and a halo CME. We
present detailed observations of the chromospheric aspects of this
event based on Hα images obtained with the ISOON telescope. The
ISOON images reveal distant flare precursor brightenings, sympathetic
flares, and, of most interest herein, four nearly cospatial propagating
chromospheric brightenings. The speeds of the propagating disturbances
causing these brightenings are 600-800 km s-1. The inferred
propagating disturbances have some of the characteristics of Hα
and EIT flare waves (e.g., speed, apparent emanation from the flare
site, subsequent filament activation). However, they differ from
typical Hα chromospheric flare waves (also known as Moreton waves)
because of their absence in off-band Hα images, small angular
arc of propagation (<30°), and their multiplicity. Three of
the four propagating disturbances consist of a series of sequential
chromospheric brightenings of network points that suddenly brighten in
the area beneath the TL that disappeared earlier. SOHO MDI magnetograms
show that the successively brightened points that define the inferred
propagating disturbances were exclusively of one polarity, corresponding
to the dominant polarity of the affected region. We speculate that
the sequential chromospheric brightenings represent footpoints of
field lines that extend into the corona, where they are energized in
sequence by magnetic reconnection as coronal fields tear away from
the chromosphere during the eruption of the transequatorial CME. We
report briefly on three other events with similar narrow propagating
disturbances that were confined to a single hemisphere.
Title: On the Origins of Solar EIT Waves
Authors: Cliver, E. W.; Laurenza, M.; Storini, M.; Thompson, B. J.
Bibcode: 2005ApJ...631..604C
Altcode:
Approximately half of the large-scale coronal waves identified in
images obtained by the Extreme-Ultraviolet Imaging Telescope (EIT) on
the Solar and Heliospheric Observatory from 1997 March to 1998 June
were associated with small solar flares with soft X-ray intensities
below C class. The probability of a given flare of this intensity
having an associated EIT wave is low. For example, of ~8,000 B-class
flares occurring during this 15 month period, only ~1% were linked to
EIT waves. These results indicate the need for a special condition that
distinguishes flares with EIT waves from the vast majority of flares
that lack wave association. Various lines of evidence, including the
fact that EIT waves have recently been shown to be highly associated
with coronal mass ejections (CMEs), suggest that this special condition
is a CME. A CME is not a sufficient condition for a detectable EIT wave,
however, because we calculate that ~5 times as many front-side CMEs
as EIT waves occurred during this period, after taking the various
visibility factors for both phenomena into account. In general, EIT
wave association increases with CME speed and width.
Title: Putting the Rubber to the Road: The Whos, Whys and Hows of
the International Heliophysical Year 2007
Authors: Thompson, B. J.; Davila, J. M.; Drobnes, E.; Gopalswamy,
N.; Wesenberg, R. P.
Bibcode: 2005AGUSM.U23A..07T
Altcode:
In 1957 a program of international research, inspired by the
International Polar Years of 1882 and 1932, was organized as the
International Geophysical Year (IGY) to study global phenomena
of the Earth and geospace. Fifty years later, the world's science
community will again come together for international programs of
scientific collaboration: the International Heliophysical Year
(IHY), the electronic Geophysical Year (eGY), and the International
Polar Year (IPY) 2007. This time, research will extend out into the
heliosphere to focus on solar-terrestrial-planetary interactions. The
ambitious plans for the IHY, eGY and IPY incorporate the activities
of scientists in 191 nations, the "IGY Gold" Historical Preservation
initiative, a series of coordinated campaigns involving more than
100 instruments and models, education and public outreach programs,
a developing nations instrument development program, and opportunities
for supported research worldwide. The presentation will focus on the
efforts and operations which will make these activities possible.
Title: Multialtitude Observations of a Coronal Jet during the Third
Whole Sun Month Campaign
Authors: Ko, Y. -K.; Raymond, J. C.; Gibson, S. E.; Alexander, D.;
Strachan, L.; Holzer, T.; Gilbert, H.; Cyr, O. C. St.; Thompson, B. J.;
Pike, C. D.; Mason, H. E.; Burkepile, J.; Thompson, W.; Fletcher, L.
Bibcode: 2005ApJ...623..519K
Altcode:
On 1999 August 26, a coronal jet occurred at the northwest limb near
a sigmoid active region (AR 8668) that was the target for a joint
observation plan (SOHO joint observing program 106) during the third
Whole Sun Month Campaign. This jet was observed by several instruments
at the limb (SOHO/CDS, SOHO/EIT, TRACE, and Mauna Loa Solar Observatory
CHIP and PICS) and at 1.64 Rsolar (SOHO/UVCS). At the limb,
this jet event displayed both low- and high-temperature components. Both
high- and low-temperature components were evident during the early phase
(first 20 minutes) of the event. However, the low-temperature component
is maintained for ~1 hr after the higher temperature component is
gone. There is a second brightening (a possible second jet) seen by
EIT and TRACE about 50 minutes after the onset of the first jet. The
line-of-sight motion at the limb began with a 300 km s-1
redshift and evolved to a 200 km s-1 blueshift. At
1.64 Rsolar, the intensities of Lyα and Lyβ in the jet
increased by a factor of several hundred compared with the background
corona. The C III λ977 line also brightened significantly. This
indicates low-temperature [~(1-2)×105 K] emission in the
jet, while the intensities of O VI λ1032 and O VI λ1037 increased
by as much as a factor of 8. The UVCS data show evidence of heating at
the early phase of the event. The Doppler shift in the lines indicates
that the line-of-sight (LOS) velocity in the jet started from ~150
km s-1 in blueshift and ended at ~100 km s-1
in redshift. This LOS motion seen at 1.64 Rsolar was
apparently opposite to what was observed when the jet emerged from the
limb. The Doppler dimming analysis indicates that the radial outflow
speed correlates with the magnitude of the LOS speed. Interestingly,
UVCS observations at 2.33 and 2.66 Rsolar show no trace of
the jet and SOHO/LASCO observations also yield no firm detection. We
find that a simple ballistic model can explain most of the dynamical
properties of this jet, while the morphology and the thermal properties
agree well with reconnection-driven X-ray jet models.
Title: High-Cadence Radio Observations of an EIT Wave
Authors: White, S. M.; Thompson, B. J.
Bibcode: 2005ApJ...620L..63W
Altcode:
Sensitive radio observations of the 1997 September 24 EIT wave show
its velocity to be 830 km s-1. The wave first appears a
short distance from the flare site, and its trajectory projects back to
the flare site at the peak of the impulsive phase. The radio spectrum
appears to be consistent with optically thin coronal emission rather
than chromospheric emission. The observed radio brightness temperatures
are consistent with the EIT fluxes if the temperature of the emitting
gas is not at the peak formation temperature of the Fe XII 195 Å line
or if abundances are closer to photospheric than coronal. An important
result is that no deceleration is observed during the 4 minutes that the
wave is visible in the radio images: the discrepancy between EIT wave
and Hα Moreton wave speeds requires that EIT waves slow substantially
as they propagate, if they are the same disturbance.
Title: Development and calibration of major components for the
STEREO/PLASTIC (plasma and suprathermal ion composition) instrument
Authors: Blush, L. M.; Allegrini, F.; Bochsler, P.; Daoudi, H.;
Galvin, A.; Karrer, R.; Kistler, L.; Klecker, B.; Möbius, E.; Opitz,
A.; Popecki, M.; Thompson, B.; Wimmer-Schweingruber, R. F.; Wurz, P.
Bibcode: 2005AdSpR..36.1544B
Altcode:
The plasma and suprathermal ion composition (PLASTIC) instrument will
measure kinetic properties and charge states of solar wind ions and
suprathermal ions as part of the solar terrestrial relations observatory
(STEREO) mission. Two identical instruments located on separate
spacecraft will provide in situ plasma measurements at ∼1 AU to study
physical processes low in the corona and in the inner heliosphere. In
conjunction with the other in situ and remote sensing instruments
of STEREO, as well as existing near-Earth observatories, the PLASTIC
instrument measurements will contribute to the understanding of the
three-dimensional structure of the heliosphere, with particular focus
on Coronal Mass Ejections. As the primary solar wind instrument aboard
STEREO, PLASTIC will measure bulk solar wind plasma parameters (density,
velocity, temperature, temperature anisotropy, and alpha/proton ratio)
and the distribution functions and charge state distributions of major
heavy solar wind ions (e.g., C, O, Ne, Mg, Si, Fe). The measurement
apparatus includes an electrostatic deflection analyzer for energy
per charge measurement ( E/ q), a time-of-flight section utilizing
carbon foils and microchannel plate detectors for time of flight
measurement ( TOF), and solid-state detectors for energy measurement
( E). The instrument will provide a large instantaneous field of view
(in-ecliptic and out-of-ecliptic angles distinguished) with measurements
taken at high time resolution (1-5 min) spanning an ion energy range
of 0.25-87 keV/e. To accommodate a large range of particle fluxes, the
PLASTIC Entrance System employs collection apertures with different
geometric factors for the bulk solar wind (H ∼ 96%, He ∼ 4%) and
for the heavy, less-abundant ions (<1%) and suprathermal ions. This
paper focuses on the hardware development of major components for the
PLASTIC instrument. The PLASTIC measurement principle is explained
along with a presentation of the ion optic calibrations of the flight
model Entrance Systems as well as calibrations of the microchannel
plates and solid-state detectors.
Title: The Solar Energetic Particle Event of 16 August 2001: ~
400 MeV Protons Following an Eruption at ~ W180
Authors: Cliver, E. W.; Thompson, B. J.; Lawrence, G. R.; Zhukov,
A. N.; Tylka, A. J.; Dietrich, W. F.; Reames, D. V.; Reiner, M. J.;
MacDowall, R . J.; Kosovichev, A. G.; Ling, A. G.
Bibcode: 2005ICRC....1..121C
Altcode: 2005ICRC...29a.121C
No abstract at ADS
Title: The Plasma and SupraThermal Ion Composition (PLASTIC)
Instrument: Final Diagnostic Development Phase for the STEREO Mission
Authors: Blush, L. M.; Bochsler, P.; Daoudi, H.; Galvin, A.; Karrer,
R.; Kistler, L.; Klecker, B.; Möbius, E.; Opitz, A.; Popecki, M.;
Thompson, B.; Wimmer-Schweingruber, R.; Wurz, P.
Bibcode: 2004AGUFMSH21B0410B
Altcode:
The PLAsma and SupraThermal Ion Composition (PLASTIC) instrument
project is entering the final phases of instrument development prior
to integration with the Solar Terrestrial Relations Observatory
(STEREO) spacecraft in early 2005. The STEREO mission will provide
a unique opportunity to investigate the 3-dimensional structure of
the heliosphere, with particular focus on the origin, evolution, and
propagation of Coronal Mass Ejections (CMEs). The mission also seeks to
determine the sites and mechanisms of energetic particle acceleration as
well as develop a 3-D time-dependent understanding of the ambient solar
wind properties. As one of four STEREO instrument packages coordinating
remote sensing and in situ measurements, the PLASTIC instruments
will diagnose properties of the solar wind and suprathermal protons,
alphas, and heavy ions. PLASTIC will determine bulk solar wind plasma
parameters (density, velocity, temperature, temperature anisotropy,
and alpha/proton ratio) and the distribution functions of major
heavy solar wind ions in the energy per charge range 0.25-100keV/e. A
full characterization of the solar wind and suprathermal ions will
be achieved with a system that measures ion energy per charge (E/q),
ion velocity distribution (ěc v), and ion energy (E). Two identical
PLASTIC instruments located on the separate spacecraft will provide
in situ plasma measurements in order to study physical processes low
in the corona and in the inner heliosphere. Elemental and charge state
abundances provide tracers of the ambient coronal plasma, fractionated
populations from coronal and heliospheric events, and local source
populations of energetic particle acceleration. In this presentation,
the PLASTIC operation principles and aims will be presented along with a
review of development status and current instrument calibration results.
Title: Coronal Shocks of November 1997 Revisited: The Cme Type II
Timing Problem
Authors: Cliver, E. W.; Nitta, N. V.; Thompson, B. J.; Zhang, J.
Bibcode: 2004SoPh..225..105C
Altcode:
We re-examine observations bearing on the origin of metric type
II bursts for six impulsive solar events in November 1997. Previous
analyses of these events indicated that the metric type IIs were due to
flares (either blast waves or ejecta). Our point of departure was the
study of Zhang et al. (2001) based on the Large Angle and Spectrometric
Coronagraph's C1 instrument (occulting disk at 1.1 R0) that
identified the rapid acceleration phase of coronal mass ejections (CMEs)
with the rise phase of soft X-ray light curves of associated flares. We
find that the inferred onset of rapid CME acceleration in each of the
six cases occurred 1-3 min before the onset of metric type II emission,
in contrast to the results of previous studies for certain of these
events that obtained CME launch times ∼25-45 min earlier than type
II onset. The removal of the CME-metric type II timing discrepancy in
these events and, more generally, the identification of the onset of
the rapid acceleration phase of CMEs with the flare impulsive phase
undercuts a significant argument against CMEs as metric type II shock
drivers. In general, the six events exhibited: (1) ample evidence
of dynamic behavior [soft X-ray ejecta, extreme ultra-violet imaging
telescope (EIT) dimming onsets, and wave initiation (observed variously
in Hα, EUV, and soft X-rays)] during the inferred fast acceleration
phases of the CMEs, consistent with the cataclysmic disruption of the
low solar atmosphere one would expect to be associated with a CME; and
(2) an organic relationship between EIT dimmings (generally taken to
be source regions of CMEs) and EIT waves (which are highly associated
with metric type II bursts) indicative of a CME-driver scenario. Our
analysis indicates that the broad (∼90° to halo) CMEs observed in
the outer LASCO coronagraphs for these impulsive events began life
as relatively small-scale structures, with angular spans of ∼15°
in the low corona. A review of on-going work bearing on other aspects
(than timing) of the question of the origin of metric type II bursts
(CME association; connectivity of metric and decametric-hectometric
type II shocks; spatial relationship between CMEs and metric shocks)
leads to the conclusion that CMEs remain a strong candidate to be
the principal/sole driver of metric type II shocks vis-à-vis flare
blast waves/ejecta.
Title: Reply to Comment on ``Moving Beyond the IGY: The Electronic
Geophysical Year (eGY) Concept''
Authors: Baker, Daniel; Barton, Charles; Rodger, Alan; Fraser, Brian;
Thompson, Barbara; Papitashvili, Vladimir
Bibcode: 2004EOSTr..85Q.302B
Altcode:
Robert Benson raises interesting points regarding the eGY and the role
of world data centers. We share the belief that the WDC system was
one of the great achievements of the IGY. We have also supported the
many and varied activities of data centers over the years. The eGY is
not intended to replace data centers, but rather to enhance them. We
believe that data center holdings should be even more accessible than
is presently the case, and that governments should support more, not
less, active archiving and tending of data. We sincerely hope that
people in the community do not interpret the eGY concept as in any
way advocating the disbanding of active data centers.
Title: A Comparison of CME-Associated Atmospheric Waves Observed in
Coronal (Fe XII 195 Å) and Chromospheric (He I 10830 Å) Lines
Authors: Gilbert, Holly R.; Holzer, Thomas E.; Thompson, Barbara J.;
Burkepile, Joan T.
Bibcode: 2004ApJ...607..540G
Altcode:
Although ``Moreton'' waves have historically been observed in Hα
data, more recently waves have also been observed in chromospheric
He I λ10830 images obtained at the Mauna Loa Solar Observatory. In
an effort to better understand the nature of chromospheric waves and
their relationship to coronal waves observed in EUV Imaging Telescope
(EIT) data, we focus on two events in which waves are observed
simultaneously in He I λ10830 and Fe XII λ195, lines that are formed
in the chromosphere and the corona, respectively. Comparing the waves
observed in these two lines allows the determination of the spatial
relationship between coronal and chromospheric waves and thus aids
in the understanding of the underlying physics of waves in the solar
atmosphere. The main goal of this work is to begin an investigation
into whether both coronal and chromospheric waves are mechanical
(e.g., MHD waves) by looking at their spatial relationship. We find
that the chromospheric waves in these two events are cospatial with
their coronal counterparts, indicating that they are not mechanical in
nature but are chromospheric imprints of mechanical waves propagating
through the corona. This conclusion is based on the nature of the
formation of the He I absorption line.
Title: Development of MHD Wave Diagnostic and Models of Coronal
Active Regions
Authors: Ofman, L.; Thompson, B. J.; Davila, J. M.
Bibcode: 2004AAS...204.9504O
Altcode: 2004BAAS...36..826O
We investigate the generation, propagation, and damping of MHD waves in
active regions, with the goal to develop a diagnostic tool of active
region structure, dynamics, and stability. We used 3D MHD model to
study the generation and the propagation of EIT waves in a simple
model of an active regions, and the interaction of EIT waves with
the active region magnetic field. We model the oscillation of active
region loops numerically using the 3D MHD model active regions. Such
oscillations have been recently observed by TRACE. We use photospheric
magnetograms as the boundary conditions for the magnetic field model,
and construct an initial field using force-free extrapolation. Finite
plasma temperature, density, and gravity are included in the model. We
construct loop density structures in the model, guided by TRACE and EIT
observations in the EUV. We demonstrate that by comparing the results
of the MHD models of waves in an active region to observations we will
be able to construct a diagnostic tool for the physical properties of
the active regions, such as magnetic field and density structure.
Title: Multi-Altitude Observations of a Coronal Jet
Authors: Ko, Y. -K.; Raymond, J. C.; Gibson, S. E.; Alexander, D.;
Strachan, L.; Holzer, T.; Gilbert, H.; St. Cyr, O. C.; Thompson,
B. J.; Pike, C. D.; Burkepile, J.; Thompson, W.; Fletcher, L.
Bibcode: 2004AAS...204.5413K
Altcode: 2004BAAS...36..759K
A coronal jet occurred on August 26, 1999 at the NW limb near a sigmoid
active region (AR8668). This jet was observed by several instruments
at the limb (SOHO/CDS, SOHO/EIT, TRACE, MLSO/CHIP, MLSO/PICS) and
at 1.64 Ro (SOHO/UVCS). At the limb, this jet event has both low and
high temperature components. The high temperature component appeared
at the early phase (first 20 minutes) of the event along with the low
temperature component while the latter seems to last long ( ∼ 1 hour)
after the higher temperature component was gone. The line-of-sight
motion at the limb started with red-shifted (by as much as 300 km/s)
and turned blue-shifted (by as much as 200 km/s). At 1.64 Ro, the
intensities of Lyα , Lyβ in the jet increased by a factor of several
hundreds compared with the background corona. C III λ 977 line also
brightened significantly. This indicates low temperature ( ∼ 1-2×
105 K) emission in the jet, while the intensities of O VI
λ 1032 and O VI λ 1037 increased by a factor of as large as 8. Both
UVCS and CDS data show evidence of heating at the early phase of the
event. The line-of-sight velocity seen at 1.64 Ro started with ∼ 150
km/sec in blue shift and ended at ∼ 100 km/sec in red shift. This is
apparently opposite to what were observed when the jet emerged from
the limb. The Doppler dimming analysis indicates that the radial
outflow speed correlates with the magnitude of the line-of-sight
speed. Interestingly, UVCS observations at 2.33 and 2.66 Ro show no
trace of the jet and LASCO observations also yield no firm sight of the
jet. In this paper, we present the observations by these instruments
and discuss the dynamical structure and physical properties of this
jet. Y.-K. Ko acknowledges the support by NASA grant NAG5-12865.
Title: The electronic Geophysical Year (eGY) 2007-2008
Authors: Barton, C.; Baker, D. N.; Fraser, B.; Papitashvili, V.;
Rodger, A.; Thompson, B.; Allen, J. H.; Arora, B.; Kerridge, D.;
Kamide, Y.
Bibcode: 2004AGUSM.U23A..03B
Altcode:
An Electronic Geophysical Year (eGY) is planned for 2007/08 as a
50-year sequel to the highly successful International Geophysical
Year. The central objective is to bring the management of geoscientific
information worldwide into the 21st century through an e-Science
approach and the development of virtual observatories. The challenge in
1957-58 was to acquire and make available to the world community the
observational data required to build a comprehensive understanding
of the Earth and its processes. That challenge remains and is
yet more pressing because of the growing demands we place on our
natural resources and environment. Our observational data gathering
capabilities have expanded enormously during the past 50 years,
particularly through space-based observations. For example, the US
National Virtual Observatory will be adding 500 TB of astronomical
data per year from 2004. This proliferation of data requires a modern,
distributed approach to data management and dissemination. To meet
this challenge, we have at our disposal the power of the Internet
and grid computing infrastructures for data sharing, processing,
and visualization. The eGY concept arose within the International
Union of Geodesy and Geophysics, with support from the Scientific
Committee on Solar-Terrestrial Physics, the International Union of
Geological Sciences, and the Society of Exploration Geophysicists, as
a means of providing an international focus for e-Science and virtual
observatory development across all the geosciences. It provides a
common thread among other global geoscientific initiatives - the 4th
International Polar Year, the International Year of Planet Earth,
the International Heliospheric Year, and Climate and Weather of the
Sun-Earth System. Virtual observatories provide exciting prospects
in the geosciences, and are under varying stages of development, for
example the Virtual Seismic Network (http://equinfo.ucsd.edu/vsn/),
the Virtual Solar Observatory (http://vso.nso.edu/), and the Virtual
Geomagnetic Observatory (http://maggy.emgin.umich.edu/mist/). It is
only a matter of time before virtual observatories are a standard
feature across all the discipline areas within the geosciences, and
add a new dimension to the role of the World Data Centers.
Title: Moving Beyond the IGY: The Electronic Geophysical Year
(eGY) Concept
Authors: Baker, D. N.; Barton, C.; Rodger, A. S.; Fraser, B.; Thompson,
B.; Papitashvili, V.
Bibcode: 2004EOSTr..85..105B
Altcode:
The International Geophysical Year (1957-1958) was inspired by the
realization that much better and more complete information was needed
about the Earth and geospace to understand and manage the complete
terrestrial environment on which we depend. So it was that the IGY
member countries worked together to deploy a large number of geophysical
observatories around the world. These nations were pursuing the major
IGY objectives to collect geophysical data as widely as possible,
and to provide free access to these data for all scientists around
the globe. About 50 permanent stations were set up in the Arctic
and Antarctic, and the World Data Center System was established
to ensure that the data collected were properly archived and made
available without restrictions for scientific research and practical
applications. IGY was an outstanding success. It elevated geophysical
monitoring to a new level, and set new standards for international
collaboration and data-sharing. Many successes of the geophysical
sciences in recent times have origins that can be traced back to the
IGY. A notable example is the modern era of space exploration. As we
approach the 50-year anniversary of the IGY, it is appropriate to seek
to build on the IGY achievements through renewed global resolves as well
as to review the outcomes of the IGY and celebrate its successes. This
is the ``IGY+50'' concept.
Title: Moving Beyond IGY: An Electronic Geophysical Year (eGY) Concept
Authors: Baker, D. N.; Barton, C. E.; Rodger, A. S.; Thompson, B. J.;
Fraser, B.; Papitashvili, V.
Bibcode: 2003AGUFM.U21A..01B
Altcode:
During the International Geophysical Year (1957-1958), member countries
established many new geophysical observatories pursuing the major IGY
objectives - to collect geophysical data as widely as possible and
to provide free access to these data for all scientists around the
globe. Today, geophysics has attained a rather good understanding
within traditional regions, i.e., the atmosphere, ionosphere,
magnetosphere, and other such geospheres. At the same time, it has
become clear that much of the new and important science is coming
from the studies of interfaces and coupling between geospheres. Thus,
if geophysical data are made `'transparently'' available to a much
wider range of scientists and students than to those who do the
observations, then new and exciting discoveries can be expected. An
International Association of Geomagnetic and Aeronomy (IAGA) task force,
recognizing that a key achievement of the IGY was the establishment
of a worldwide system of data centers and physical observatories,
proposes that for the 50th anniversary of IGY, the worldwide scientific
community should endorse and promote an electronic Geophysical Year
(eGY) initiative. The proposed eGY concept would both commemorate
the IGY in 2007-2008 and provide a forward impetus to geophysics
in 21st century, similar to that provided by the IGY fifty years
ago. The IAGA task force strongly advocates: (1) Securing permission
and release of existing data; (2) Creating access to information;
and (3) Conversion of relevant analog data to digital form. The eGY
concept embraces all available and upcoming geophysical data (e.g.,
atmospheric, ionospheric, geomagnetic, gravity, etc.) through the
establishment of a series of virtual geophysical observatories now
being `'deployed'' in cyberspace. The eGY concept is modern, global,
and timely; it is attractive, pragmatic, and affordable. The eGY is
based on the existing and continually developing computing/networking
technologies (e.g., XML, Semantic Web, etc.) and international cyber
infrastructure. Moreover, the International Union of Geodesy and
Geophysics (IUGG) has supported the eGY concept, which can smoothly be
incorporated into various existing `'International Year'' initiatives -
such as the International Polar Year, International Heliophysical Year,
or International Year of the Planet Earth.
Title: A Survey of Coronal Dimmings and EIT Wave Transients
Authors: West, M.; Thompson, B. J.
Bibcode: 2003AGUFMSH22B..01W
Altcode:
We present the results of a comprehensive catalog of EIT wave
transients and coronal dimmings. We will compiled a set of more than
170 events, and we present strong evidence for the association of
the co-development of coronal dimmings and EIT waves. Both limb and
disk events are included in this study. We also include the speeds,
locations, and associated flare timing in this study.
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.
Bibcode: 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: High-Energy 3He-Rich Solar Particle Events
Authors: Torsti, Jarmo; Kocharov, Leon; Laivola, Jarno; Chertok,
Ilya; Thompson, Barbara J.
Bibcode: 2003SoPh..214..177T
Altcode:
Energetic particle observations of the ERNE instrument on board SOHO
enable measurements of 3He and 4He fluxes beyond
15 MeV nucleon−1 with good statistical resolution. We
report results of a survey of the ERNE observations covering the period
from 8 February 1999 to 6 December 2000. We find 10 and 5 days during
which the 3He-to-4He ratio exceeds the levels
of 20% and 50%, respectively. Those periods include, in particular,
four 3He-rich events that are sufficiently strong for
a reasonably accurate estimate of the time-intensity profiles. We
analyze the history of solar and interplanetary phenomena associated
with these high-energy 3He-rich events. Basic properties
of such events and significant solar and interplanetary factors are
formulated. The significant factors comprise, in particular, a strong,
impulsive flare, typically observed about day before the 3He
onset, and an interplanetary shock wave or magnetic field enhancement
arriving at 1 AU about frac43 day after the 3He onset. The
high-energy 3He-rich events make up a new kind of hybrid
events, possessing the impulsive-type composition and the gradual-type
time-profiles. We emphasize a dependence of the resultant particle
event on the history of the particular solar eruption comprising
coronal mass ejection (CME) and the flare associated with the CME.
Title: The "Whole Sun Month" Campaigns As a Prototype for IHY
Authors: Thompson, B. J.; Biesecker, D. A.; Breen, A. R.; Gibson, S. E.
Bibcode: 2003EAEJA....11571T
Altcode:
The International Heliophysical Year (IHY) in 2007 will consist of
a series of coordinated observations combining data and models from
an expansive group of international participants. Campaigns will be
planned to target all aspects of heliophysics, including solar and
interplanetary physics, geospace science and the climatary impact
on Earth. These campaigns will require extensive coordination to
ensure that available ground-based and space missions are utilized
to the greatest scientific benefit. The "Whole Sun Month" campaigns
serve as an excellent prototype for IHY. The first Whole Sun Month
campaign (10 August - 8 September 1996) consisted of an entire
month of coordinated solar and heliospheric observations, followed
by workshops which combined the analysis of the campaign data with
the utilization of these data to constrain interpretive 3-D models
solar and heliospheric structure. The subsequent campaigns (in 1998
and 1999) targetted more specific topics, again allowing a broad base
of participants to establish a comprehensive base of observations for
model interpretation. The many scientific successes of the Whole Sun
Month campaigns (publications, workshops, model refinement and ongoing
collaborations) and the framework of campaign coordination provides an
excellent basis for the planning of IHY campaigns. We will discuss the
campaigns in detail and begin an outline for how the campaigns could
be expanded to incorporate more observations and a greater timeline
for IHY.
Title: Drinking From the Data Firehose: The SDO Ground System
Authors: Pages, R.; Potter, W. J.; Thompson, B. J.
Bibcode: 2002AGUFMSH21C..07P
Altcode:
The Solar Dynamics Observatory will generate an unprecedented space
science data stream of 150 Mbps. The primary challenge of the SDO Ground
System is to provide continuous, near-real-time science delivery of
the large volumes of science data. Other challenges include high data
completeness requirements and utilization of a new Ka band antenna
network for the data capture. The presentation will report on the
progress of the SDO Ground Systems team in designing a cost-effective,
reliable ground system for SDO.
Title: Two wave morphologies in SOHO/EIT - EIT waves and Moreton waves
Authors: Biesecker, D. A.; Thompson, B. J.; Hudson, H. S.; Warmuth,
A.; White, S.
Bibcode: 2002AGUFMSH52A0450B
Altcode:
EIT waves are global waves observed to propagate across quiet
coronal field regions in the SOHO/EIT data. The waves are initiated in
association with other transient activity. The literature now contains
many references to EIT waves and observers have published observations
of associated waves at a variety of wavelengths. We show in this
poster that there is confusion in the literature as to what an EIT
wave is. We use YOHKOH SXT, Nobeyama Radioheliograph and He I 10830A
observations to show that the EIT instrument observes waves with two
distinct properties and morphologies. These two morphologies correspond
to the classical Moreton wave and to what we call the EIT wave. The
Moreton waves in EIT appear as a sharp, bright feature, travelling at
super-Alfvenic velocities. The EIT waves instead appear as a diffuse,
faint feature, moving at relatively slower velocities. The EIT waves
appear much more frequently than the Moreton waves and Moreton waves
are usually seen in tandem with EIT waves. Both types of waves have
been modelled by various researchers as MHD waves.
Title: The SDO Mission
Authors: Schwer, K.; Lilly, R. B.; Thompson, B. J.; Brewer, D. A.
Bibcode: 2002AGUFMSH21C..01S
Altcode:
The Solar Dynamics Observatory, scheduled to launch in August 2007, will
view the Sun continuously from an inclined geosynchronous orbit. The
spacecraft will be a robust, three-axis stabilized spacecraft with
low jitter and will deliver 150 Mbps of continuous high rate data. The
spacecraft will be built, tested and integrated in-house at the NASA
Goddard Space Flight Center, with four instruments to be developed
by three Principal Investigator teams. The primary challenges include
maintaining an ambitious schedule, designing a communications and ground
system which can handle an unprecedented volume of space science data,
and a baseline of five years reliability. The presentation will focus
on the progress of the GSFC SDO Project team in developing the Solar
Dynamics Observatory.
Title: EUV Dimmings: Simple or Enigmatic?
Authors: Thompson, B.; Biesecker, D. A.; Ofman, L.; St. Cyr, O. C.;
Wills-Davey, M. J.
Bibcode: 2002AGUFMSH52A0488T
Altcode:
EUV dimmings are large-scale depletions in coronal EUV emission
associated with coronal mass ejections. Their occurrence is nearly
perfect in correlation with fast CMEs. Many of the EUV dimming
observations appear to correspond well in appearance and behavior to
SXR dimmings. It has been assumed that the dimmings are merely the
location of the CME mass removal in the corona, and that their similar
appearance to coronal holes is because they are transient coronal
holes with fieldlines opened by the coronal mass ejection. However,
not all CMEs have dimmings, and large-scale EUV dimmings have also
been caused by heating of local plasma, and due to absorption by cool
material "clouds" evolving in the wake of an eruption. Additionally,
there are several ways in which these regions "heal," presumably due to
the closing down of the open field lines. The presentation will include
a range of EUV dimming observations, a discussion of their origin,
and what they might imply about the nature of the associated CMEs.
Title: SDO: A Systems Challenge
Authors: Ruffa, J.; Ward, D. K.; Anderson, T. A.; Schwer, K. O.;
Thompson, B. J.
Bibcode: 2002AGUFMSH51A0435R
Altcode:
The Solar Dynamics Observatory, scheduled to launch in August 2007,
presents several significant challenges to the Systems Engineering
team. The spacecraft will be built, tested and integrated in-house
at the NASA Goddard Space Flight Center, with four instruments to
be developed by three Principal Investigator teams. Though few new
technologies are required in developing a robust, reliable and versatile
spacecraft, the combination of numerous requirements (scientific and
otherwise) require a significant effort to ensure complete mission
success. The presentation will include a discussion of the SDO
subsystems and the status of the SDO Systems Engineering team efforts.
Title: The International Heliophysical Year (IHY)
Authors: Davila, J. M.; Harrison, R.; Poland, A.; Thompson, B.;
Gopalswamy, N.
Bibcode: 2002AGUFMSH21A0518D
Altcode:
In 1957 a program of international research, inspired by the
International Polar Years of 1882-83 and 1932-33, was organized as
the International Geophysical Year (IGY) to study global phenomena of
the Earth and geospace. The IGY involved about 60,000 scientists from
66 nations, working at thousands of stations, from pole to pole to
obtain simultaneous, global observations on Earth and in space. There
had never been anything like it before. The fiftieth anniversary of
the International Geophysical Year will occur in 2007. We propose to
organize an international program of scientific collaboration for this
time period called the International Heliophysical Year (IHY). Like
it predecessors, the IHY will focus on fundamental global questions
of Earth science.
Title: The Structure and Evolution of a Sigmoidal Active Region
Authors: Gibson, S. E.; Fletcher, L.; Del Zanna, G.; Pike, C. D.;
Mason, H. E.; Mandrini, C. H.; Démoulin, P.; Gilbert, H.; Burkepile,
J.; Holzer, T.; Alexander, D.; Liu, Y.; Nitta, N.; Qiu, J.; Schmieder,
B.; Thompson, B. J.
Bibcode: 2002ApJ...574.1021G
Altcode:
Solar coronal sigmoidal active regions have been shown to be precursors
to some coronal mass ejections. Sigmoids, or S-shaped structures,
may be indicators of twisted or helical magnetic structures, having
an increased likelihood of eruption. We present here an analysis of a
sigmoidal region's three-dimensional structure and how it evolves in
relation to its eruptive dynamics. We use data taken during a recent
study of a sigmoidal active region passing across the solar disk
(an element of the third Whole Sun Month campaign). While S-shaped
structures are generally observed in soft X-ray (SXR) emission, the
observations that we present demonstrate their visibility at a range of
wavelengths including those showing an associated sigmoidal filament. We
examine the relationship between the S-shaped structures seen in SXR
and those seen in cooler lines in order to probe the sigmoidal region's
three-dimensional density and temperature structure. We also consider
magnetic field observations and extrapolations in relation to these
coronal structures. We present an interpretation of the disk passage
of the sigmoidal region, in terms of a twisted magnetic flux rope
that emerges into and equilibrates with overlying coronal magnetic
field structures, which explains many of the key observed aspects of
the region's structure and evolution. In particular, the evolving flux
rope interpretation provides insight into why and how the region moves
between active and quiescent phases, how the region's sigmoidicity is
maintained during its evolution, and under what circumstances sigmoidal
structures are apparent at a range of wavelengths.
Title: Interaction of EIT Waves with Coronal Active Regions
Authors: Ofman, L.; Thompson, B. J.
Bibcode: 2002ApJ...574..440O
Altcode:
Large-scale coronal waves associated with flares were first observed
by the Solar and Heliospheric Observatory (SOHO) Extreme ultraviolet
Imaging Telescope (EIT). We present the first three-dimensional MHD
modeling of the interaction of the EIT waves with active regions and the
possibility of destabilization of an active region by these waves. The
active region is modeled by an initially force-free, bipolar magnetic
configuration with gravitationally stratified density. We include
finite thermal pressure and resistive dissipation in our model. The
EIT wave is launched at the boundary of the region, as a short time
velocity pulse that travels with the local fast magnetosonic speed
toward the active region. We find that the EIT wave undergoes strong
reflection and refraction, in agreement with observations, and induces
transient currents in the active region. The resulting Lorentz force
leads to the dynamic distortion of the magnetic field and to the
generation of secondary waves. The resulting magnetic compression
of the plasma induces flows, which are particularly strong in the
current-carrying active region. We investigate the effect of the
magnetic field configuration and find that the current-carrying active
region is destabilized by the impact of the wave. Analysis of the
three-dimensional interaction between EIT waves and active regions can
serve as a diagnostic of the active region coronal magnetic structure
and stability.
Title: Halo-coronal mass ejections near the 23rd solar minimum:
lift-off, inner heliosphere, and in situ (1 AU) signatures
Authors: Berdichevsky, D. B.; Farrugia, C. J.; Thompson, B. J.;
Lepping, R. P.; Reames, D. V.; Kaiser, M. L.; Steinberg, J. T.;
Plunkett, S. P.; Michels, D. J.
Bibcode: 2002AnGeo..20..891B
Altcode:
The extreme ultraviolet (EUV) signatures of a solar lift-off, decametric
and kilometric radio burst emissions and energetic particle (EP)
inner heliospheric signatures of an interplanetary shock, and in
situ identification of its driver through solar wind observations
are discussed for 12 isolated halo coronal mass ejections (H-CMEs)
occurring between December 1996 and 1997. For the aforementioned twelve
and the one event added in the discussion, it is found that ten passed
several necessary conditions for being a "Sun-Earth connection". It
is found that low corona EUV and Ha
Title: Relation between a Moreton Wave and an EIT Wave Observed on
1997 November 4
Authors: Eto, Shigeru; Isobe, Hiroaki; Narukage, Noriyuki; Asai, Ayumi;
Morimoto, Taro; Thompson, Barbara; Yashiro, Seiji; Wang, Tongjiang;
Kitai, Reizaburo; Kurokawa, Hiroki; Shibata, Kazunari
Bibcode: 2002PASJ...54..481E
Altcode:
We consider the relationship between two flare-associated waves,
a chromospheric Moreton wave and a coronal EIT wave, based on an
analysis of an X-class flare event in AR 8100 on 1997 November 4. A
Moreton wave was observed in Hα + 0.8 Å, and Hα - 0.8 Å with the
Flare-Monitoring Telescope (FMT) at the Hida Observatory. An EIT wave
was observed in EUV with the Extreme ultraviolet Imaging Telescope
(EIT) on board SOHO. The propagation speeds of the Moreton wave and
the EIT wave were approximately 715 km s-1 and 202 km
s-1, respectively. The times of visibility for the Moreton
wave did not overlap those of the EIT wave, but the continuation of the
former is indicated by a filament oscillation. Data on the speed and
location clearly show that the Moreton wave differed physically from
the EIT wave in this case. The Moreton wave preceded the EIT wave,
which is inconsistent with an identification of the EIT wave with a
fast-mode MHD shock.
Title: Radio Observations of the Onset of an EIT Wave
Authors: White, S. M.; Thompson, B. J.
Bibcode: 2002AAS...200.2904W
Altcode: 2002BAAS...34R.681W
We present observations of the early development of an ``EIT wave'' made
with the Nobeyama Radio Heliograph at 17 GHz. EIT waves are propagating
disturbances generated in conjunction with solar flares. They have
most easily been seen to date as emission enhancements in full-disk
EUV images taken in spectral lines sensitive to 1-2 million degree
material. We demonstrate that they can also be seen in high dynamic
range radio observations as well. The high cadence of the radio data
allows us to show that the EIT wave is not visible until after the onset
of the impulsive phase of the flare. A radio movie of the event will
be shown. We discuss the implications of this result for the nature
of EIT waves and their relationship with other phenomena such as CMEs.
Title: Can EIT Waves be used to Predict Halo CME Properties?
Authors: Biesecker, D. A.; Thompson, B. J.
Bibcode: 2002AAS...200.3708B
Altcode: 2002BAAS...34..695B
A recent paper by Biesecker et al (2002) showed that EIT waves are
correlated with Coronal Mass Ejections. Not all CME's produce EIT
waves, but all EIT waves have associated CME's. If one assumes that
an EIT wave is a response to the initiation of a CME, then there
may be circumstances where EIT wave properties would be related to
CME properties. EIT waves have been modelled as fast magnetosonic
waves. Thus, their propagation speed across the solar disk depends
on the local magnetic field and density and one would not expect a
correlation between EIT wave speeds and CME properties, such as speed
or intensity. On the other hand, one might expect the intensity of
the EIT wave to be related to CME properties. If such an association
can be found, then observations of EIT waves at disk center will give
information about Earth directed CME's which is currently hard to
determine. This work examines EIT waves initiated at large distances
from disk center, so that the associated CME's are well observed. EIT
wave speeds and intensities are compared to CME speed, intensity and
other properties, such as kinetic energy.
Title: A Comparison of CME-associated Atmospheric Waves Observed in
Coronal (Fe XII 19.5 nm) and Chromospheric (He I 1083 nm) Lines
Authors: Gilbert, H. R.; Thompson, B. J.; Holzer, T. E.; Burkepile,
J. T.
Bibcode: 2002AAS...200.3808G
Altcode: 2002BAAS...34..699G
In an effort to better understand the relationship between coronal waves
(EIT waves) and chromospheric waves, we study two events in which waves
are observed simultaneously in both Fe XII (19.5 nm) and He I (1083 nm):
lines formed in the corona and chromosphere, respectively. Comparing
the waves observed in these two lines allows the determination of the
spatial relationship between coronal and chromospheric waves, and thus
aids in the understanding of the underlying physics of waves. The main
goal of this work is to begin an investigation into whether coronal
and chromospheric waves are both mechanical waves (e.g., MHD waves),
or whether chromospheric waves are simply "reflections" of mechanical
waves propagating in the corona.
Title: Gravity Recovery and Precise Orbit Determination With CHAMP
Authors: Lemoine, F. G.; Luthcke, S. B.; Rowlands, D. D.; Cox, C. M.;
Chinn, D. S.; Pavlis, D. E.; Williams, T.; Thompson, B.; Nerem, R. S.
Bibcode: 2002AGUSM.G22A..10L
Altcode:
The CHAMP mission, launched in July 2000, is the first in a series
of missions that will revolutionize our ability to model the Earth's
geopotential. The CHAMP spacecraft is equiped for precision tracking
by the Global Positioning System (GPS) and Satellite laser ranging
(SLR) and along with precision accelerometer to provide measurements
of the surface forces. In preparation for CHAMP and GRACE, extensive
modifications have been made to NASA GSFC's GEODYN orbit determination
software to enable the simultaneous reduction of spacecraft tracking,
three-axis accelerometry, and precise attitude data. We report in this
paper on the analysis of over 80 days CHAMP tracking and accelerometry
and how these data contribute to satellite-only and combination
geopotential solutions for the Earth. We evaluate the quality of the
precise orbits and summarize the strategies we have applied in our
GPS orbit analyses.
Title: Solar Phenomena Associated with ``EIT Waves''
Authors: Biesecker, D. A.; Myers, D. C.; Thompson, B. J.; Hammer,
D. M.; Vourlidas, A.
Bibcode: 2002ApJ...569.1009B
Altcode:
In an effort to understand what an ``EIT wave'' is and what its causes
are, we have looked for correlations between the initiation of EIT
waves and the occurrence of other solar phenomena. An EIT wave is
a coronal disturbance, typically appearing as a diffuse brightening
propagating across the Sun. A catalog of EIT waves, covering the period
from 1997 March through 1998 June, was used in this study. For each
EIT wave, the catalog gives the heliographic location and a rating
for each wave, where the rating is determined by the reliability of
the observations. Since EIT waves are transient, coronal phenomena, we
have looked for correlations with other transient, coronal phenomena:
X-ray flares, coronal mass ejections (CMEs), and metric type II radio
bursts. An unambiguous correlation between EIT waves and CMEs has been
found. The correlation of EIT waves with flares is significantly weaker,
and EIT waves frequently are not accompanied by radio bursts. To
search for trends in the data, proxies for each of these transient
phenomena are examined. We also use the accumulated data to show the
robustness of the catalog and to reveal biases that must be accounted
for in this study.
Title: What is the source of the magnetic helicity shed by CMEs? The
long-term helicity budget of AR 7978
Authors: Démoulin, P.; Mandrini, C. H.; van Driel-Gesztelyi, L.;
Thompson, B. J.; Plunkett, S.; Kovári, Zs.; Aulanier, G.; Young, A.
Bibcode: 2002A&A...382..650D
Altcode:
An isolated active region (AR) was observed on the Sun during seven
rotations, starting from its birth in July 1996 to its full dispersion
in December 1996. We analyse the long-term budget of the AR relative
magnetic helicity. Firstly, we calculate the helicity injected
by differential rotation at the photospheric level using MDI/SoHO
magnetograms. Secondly, we compute the coronal magnetic field and
its helicity selecting the model which best fits the soft X-ray loops
observed with SXT/Yohkoh. Finally, we identify all the coronal mass
ejections (CMEs) that originated from the AR during its lifetime using
LASCO and EIT/SoHO. Assuming a one to one correspondence between CMEs
and magnetic clouds, we estimate the magnetic helicity which could be
shed via CMEs. We find that differential rotation can neither provide
the required magnetic helicity to the coronal field (at least a factor
2.5 to 4 larger), nor to the field ejected to the interplanetary
space (a factor 4 to 20 larger), even in the case of this AR for
which the total helicity injected by differential rotation is close
to the maximum possible value. However, the total helicity ejected is
equivalent to that of a twisted flux tube having the same magnetic flux
as the studied AR and a number of turns in the interval [0.5,2.0]. We
suggest that the main source of helicity is the inherent twist of the
magnetic flux tube forming the active region. This magnetic helicity
is transferred to the corona either by the continuous emergence of the
flux tube for several solar rotations (i.e. on a time scale much longer
than the classical emergence phase), or by torsional Alfvén waves.
Title: New insights on the onsets of coronal mass ejections from soho
Authors: Plunkett, S. P.; Michels, D. J.; Howard, R. A.; Brueckner,
G. E.; St. Cyr, O. C.; Thompson, B. J.; Simnett, G. M.; Schwenn, R.;
Lamy, P.
Bibcode: 2002AdSpR..29.1473P
Altcode:
Coronal mass ejections (CMES) are among the most dramatic forms of
transient activity occurring in the solar atmosphere. Despite over
twenty years of research, many basic questions related to the physics
of CMEs have remained unanswered. Observations with the LASCO and EIT
experiments on SOHO, combined with recent theoretical modeling, have
provided new insights on some of these outstanding questions and have
also raised many new ones that need to be addressed in the future. In
this paper, we present some of the new results from SOHO pertaining
to the source regions and onsets of CMEs, and their evolution in the
corona. We emphasize the important role that studies of CMEs will play
in the International Solar Cycle Studies program.
Title: Helicity Loading and Dissipation: The Helicity Budget of AR
7978 from the Cradle to the Grave
Authors: van Driel-Gesztelyi, L.; Démoulin, P.; Mandrini, C. H.;
Plunkett, S.; Thompson, B.; Kövári, Zs.; Aulanier, G.; Young, A.;
López Fuentes, M.; Poedts, S.
Bibcode: 2002mwoc.conf..143V
Altcode:
An isolated active region was observed on the Sun during seven
rotations, starting in July 1996. I will present a study of its magnetic
field, concentrating on its helicity budget. The photospheric field
is extrapolated into the corona in a linear force-free approach,
using SOHO/MDI magnetograms and Yohkoh/SXT images, allowing us to
compute, in a crude way, the relative coronal magnetic helicity of
the active region. Using the observed magnetic field distribution
(SOHO/MDI magnetograms) we also calculate the helicity injected by
the differential rotation during seven solar rotations. Finally, using
SOHO/LASCO and EIT as well as Yohkoh/SXT observations, we identify all
the 26 CMEs which originated from this active region during its lifetime
and using average values of the field and radius of magnetic clouds,
we estimate the helicity which should be shed via CMEs. We compare
these three values to evaluate the importance of the differential
rotation relative to twisted flux emergence as a source of magnetic
helicity. We find that the differential rotation can neither provide
enough helicity to account for the diagnosed coronal heicity values,
nor for the helicity carried away by CMEs. We suggest that the main
source of the magnetic helicity must be the inherent twist of the
magnetic flux tube forming the active region. This magnetic helicity is
transferred to the corona either by a slow continuous emergence of the
flux tube or by torsional Alfven waves, during several solar rotations.
Title: Solar particle events with helium-over-hydrogen enhancement
in the energy range up to 100 MeV nucl−1
Authors: Torsti, J.; Kocharov, L.; Laivola, J.; Pohjolainen, S.;
Plunkett, S. P.; Thompson, B. J.; Kaiser, M. L.; Reiner, M. J.
Bibcode: 2002SoPh..205..123T
Altcode:
Flux measurements of solar energetic particles (SEPs) in the
ERNE instrument onboard SOHO indicate that the abundance of
4He-nuclei compared to protons in the energy range up to
100 MeV nucl−1 was exceptionally high during the particle
events on 27 May 1998 and 28 December 1999. The 4He/p ratio
stayed between 0.15-0.50 for more than ten hours. There was also
a prolonged enhancement in helium-3, 3He/4H
≈1%. Observations of EIT and LASCO on board SOHO confirm that the
originators of both SEP events were western eruptions, flares and
coronal mass ejections (CMEs). The onset of the SEP release took
place close to the maximum of flares which were probably triggered
by the rising CMEs. The observations suggest that the SEP events were
started with the flare-(pre)accelerated particles, but impact of the
CME-associated shocks might explain the continuation and modification
of the helium and proton fluxes well after the flare production. These
observations support the idea that the helium enhancements in the
CME-associated events reflect the availability of seed particles that
originate previously in flares.
Title: Using Solar Wind Composition As A Tracer For Solar Processes:
Applications For Plastic On Stereo
Authors: Wimmer-Schweingruber, Robert F.; Allegrini, Frédéric;
Blush, Lisa; Bochsler, Peter; Fischer, Josef; Wurz, Peter; Galvin,
A. B.; Moebius, E.; Klecker, B.; Thompson, B.; Plastic Team
Bibcode: 2002EGSGA..27.2220W
Altcode:
Solar wind composition is increasingly being used as a tracer for
various processes in the solar atmosphere and in interplanetary
space. We will discuss applications of solar wind composition
measurements that are relevant for the STEREO mission and that will be
supplied by the PLASTIC sensor. Solar wind elemental abundances
are affected by processes acting in the solar interior, chromosphere,
and in the corona, while charge-state composition is largely determined
in the corona. Farther out in the inner heliosphere, composition
measurements can give information about interplanetary processes and
serves as an excellent tracer for the coronal and chromospheric origin
of the measured solar wind. Coronal mass ejections often exhibit
unusual charge-state and elemental composition that is indicative of
unusual conditions in the solar atmosphere prior and during the launch
of the ejection. We will discuss observational opportunities
unique to collaborative studies with vari- ous instruments on STEREO.
Title: Radio Shocks from Reconnection Outflow Jet? - New Observations
Authors: Aurass, H.; Karlicky, M.; Thompson, B. J.; Vršnak, B.
Bibcode: 2002mwoc.conf..401A
Altcode:
The common analysis of dynamic radio spectrograms with Yohkoh X-ray
images yields information about possible associations between
nonthermal electron acceleration and changes in hot and dense
plasma-magnetic field structures of the corona. Examples are correlated
X-ray-jet--electron beam injections (type III/U bursts), motions of
X-ray blobs and correlated shock-driven (type II) radio bursts, and
sigmoid evolution associated with characteristic type IV burst spectral
fine structures. Here, we demonstrate the first identification of the
radio signature of a reconnection outflow termination shock during a
dynamic flare. Reconnection of magnetic fields is one flare energy
release mechanism. During dynamic flares there is formed a system
of standing slow and - sometimes - also fast mode shock waves in the
space around the diffusion region. This standing fast mode shock is
revealed by a zero-drift type II burst between 300 and 400 MHz. It
exists more than 30 min starting 1 hour after the impulsive flare on
07 April 1997 in AR 8027. It shows herringbone fine structure and 10%
band splitted lanes. We argue for having detected fundamental mode
emission. No fundamental-harmonic pattern was observed. Simultaneous
imaging observations (Hα, Yohkoh SXT, SOHO EIT) show a postflare loop
arcade with a bright soft X-ray cusp. Preferable conditions for the
radio detection of the termination shock are a low plasma to magnetic
pressure ratio eta upstream of the slow shocks, a low diffusion region
rise velocity, and a low reconnection rate. The occurrence of the
termination shock is most probable in late stage of flares.
Title: SXT and EIT Observations of A Quiet Region Large-Scale
Eruption: Implications for Eruption Theories
Authors: Sterling, A. C.; Moore, R. L.; Thompson, B. J.
Bibcode: 2002mwoc.conf..165S
Altcode:
We present Yohkoh/SXT and SOHO/EIT observations of a set of slow, large
scale, quiet-region solar eruptions. In SXT data, these events seem to
appear ``out of nothing,'' indicating that they are associated initially
with weak magnetic fields and corresponding low heating rates. These
events evolve relatively slowly, affording us an opportunity to
examine in detail their development. We look for signatures of the
start of the eruptions through intensity variations, physical motions,
and dimming signatures in the SXT and EIT data. In particular, we look
to see whether the earliest signatures are brightenings occurring in
the ``core'' region (i.e., the location where the magnetic shear is
strongest and the post-flare loops develop); such early brightenings in
the core could be indicative of a ``tether-cutting'' process, whereby
the eruption is instigated by magnetic reconnection among highly-sheared
core fields. In our best-observed case, we find motions of the core
fields beginning well before brightenings in the core. This is new
evidence that tether-cutting is not the primary mechanism operating
in solar eruptions. Rather, our observations are more consistent with
the eruption process known as the ``breakout model'' (Antiochos et
al. 1999), which holds that the eruption results from initial slow
magnetic reconnections occurring high above (far from) the core region.
Title: Progress Towards the Solar Dynamics Observatory
Authors: Thompson, B.; Schwer, K.
Bibcode: 2002cosp...34E1987T
Altcode: 2002cosp.meetE1987T
The Solar Dynamics Observatory, or SDO, is scheduled to be the first
mission to launch in 2007 under the new Living With a Star (LWS)
program. It builds on the success of SOHO and other recent solar
missions, but will observe the Sun at greater resolution and faster
time cadence with a set of remote sensing instruments generating data
in excess of 100 Mbps. The Science Definition Team produced a report
consisting of a series of science objectives and a baseline instrument
complement. Instrument proposals were due in April 2002, with selection
to occur in the late summer of 2002. The spacecraft is being built
at NASA Goddard Spacecraft Center by a team of engineers which are
currently undergoing the formulation process. The presentation will
discuss the current status of the science investigation selection and
the spacecraft formulation.
Title: Upstream Shocks and Interplanetary Magnetic Cloud Speed and
Expansion: Sun, Wind, and Earth Observations
Authors: Lepping, R. P.; Berdichevsky, D.; Szabo, A.; Lazarus, A. J.;
Thompson, B. J.
Bibcode: 2002swsm.conf...87L
Altcode:
No abstract at ADS
Title: Observations of Moreton Waves and EIT Waves
Authors: Shibata, K.; Eto, S.; Narukage, N.; Isobe, H.; Morimoto,
T.; Kozu, H.; Asai, A.; Ishii, T.; Akiyama, S.; Ueno, S.; Kitai, R.;
Kurokawa, H.; Yashiro, S.; Thompson, B. J.; Wang, T.; Hudson, H. S.
Bibcode: 2002mwoc.conf..279S
Altcode:
The Moreton wave is a flare-associated wave observed in H alpha, and
is now established to be a fast mode MHD shock emitted from the flare,
but the physical mechanism to create the wave is still puzzling. On
the other hand, the EIT wave is a newly discovered flare-associated
wave observed in EUV with the Extreme ultraviolet Imaging Telescope
(EIT) aboard SOHO, and in this case, not only its origin but also
its physical property are both puzzling. We study the relationship
of these two flare-associated waves, Moreton waves and EIT waves, by
analyzing 4 events observed on Nov. 3 and 4, 1997, Aug. 8, 1998, and
Mar. 3, 2000 (Narukage et al. 2001). The Moreton waves were observed
in Ha, Ha+0.8A and Ha-0.8A with the Flare Monitoring Telescope (FMT)
at the Hida Observatory of Kyoto University, while the EIT waves were
observed with SOHO/EIT. In the typical case associated with an X-class
flare in AR 8100 on 4 November 1997 (Eto et al. 2001) the propagation
speeds of the Moreton wave and the EIT wave were approximately 780
km/s and 200 km/s respectively. The data on speed and location show
clearly that the Moreton wave differs physically from the EIT wave in
this case. The detailed analyses of the other events (Nov. 3, 1997,
Aug. 8, 1998, and Mar. 3, 2000) will also be presented, with Yohkoh/SXT
data in the lucky case.
Title: Phenomena Associated with EIT Waves
Authors: Thompson, B.; Biesecker, D.; Gopalswamy, N.
Bibcode: 2002cosp...34E2672T
Altcode: 2002cosp.meetE2672T
We discuss phenomena associated with "EIT Wave" transients. "EIT
Waves" are propagating disturbances first observed in SOHO/EIT EUV
images. However, a number of studies have been conducted to determine
their relationship to other observations, using data from a variety
of instruments. These phenomena include coronal mass ejections,
flares, EUV/SXR dimmings,chromospheric waves, Moreton waves, solar
energetic particle events, energetic electron events, and radio
signatures. Although the occurrence of many phenomena correlate with the
appearance of EIT waves, it is difficult to infer which associations are
causal. The presentation will include a discussion of the correlation
statistics of these phenomena.
Title: The International Heliophysical Year Concept
Authors: Davila, J.; Harrison, R.; Poland, A.; St-Cyr, O.; Thompson, B.
Bibcode: 2002cosp...34E.529D
Altcode: 2002cosp.meetE.529D
In 1957 a program of international research, inspired by the
International Polar Years of 1882-83 and 1932-33, was organized as
the International Geophysical Year (IGY) to study global phenomena of
the Earth and geospace. The IGY involved about 60,000 scientists from
66 nations, working at thousands of stations, from pole to pole to
obtain simultaneous, global observations on Earth and in space. There
had never been anything like it before. The fiftieth anniversary of
the International Geophysical Year will occur in 2007. We propose to
organize an international program of scientific collaboration for this
time period called the International Heliophysical Year (IHY). Like
its predecessors, the IHY will focus on fundamental global questions
of Earth science.
Title: Relationships between CME's and prominences
Authors: Schmieder, B.; van Driel-Gesztelyi, L.; Aulanier, G.;
Démoulin, P.; Thompson, B.; De Forest, C.; Wiik, J. E.; Saint Cyr,
C.; Vial, J. C.
Bibcode: 2002AdSpR..29.1451S
Altcode:
We have studied the erupting prominences which were associated with
coronal mass ejections during a series of campaigns involving both
spacecraft and ground-based observatories. The evolution of the
physical conditions within the prominences was established from Hα
and magnetic field observations. Particular attention ahs been paid
to the presence of mixed amgnetic polarity in the filament channel,
the evolution of the shear of the large-scale magnetic field, and
the existence of multiple magnetic inversion lines. We conclude that
reconnection of large-scale coronal magnetic fields is responsible
for both the CME and filament eruption.
Title: Erupting Solar Magnetic Flux Ropes: Theory and Observation
Authors: Krall, J.; Chen, J.; Duffin, R. T.; Howard, R. A.; Thompson,
B. J.
Bibcode: 2001ApJ...562.1045K
Altcode:
Measurements of coronograph (LASCO) and extreme-ultraviolet (EIT)
images are presented for 11 coronal mass ejection (CME) events. Detailed
measurements of these events, selected because they have flux-rope-like
morphological features, show excellent agreement with results from a
theoretical model of erupting flux-rope dynamics. Here, data are used
to provide inputs and constraints on the model wherever possible. We
conclude that flux rope CMEs constitute a distinct class of CMEs,
characterized by specific morphological and dynamical properties.
Title: Proton Storms Associated with Far-Sided Coronal Mass Ejections
Authors: Lawrence, G. R.; Thompson, B. J.
Bibcode: 2001AGUFMSH41B0753L
Altcode:
A fast, bright, full-halo CME, characterised by emission around all 360
degrees of the occulting disk, was observed late on August 15th 2001
by the LASCO white-light coronagraphs onboard SOHO, and was followed
within an hour by an intense proton storm at 1 AU. Such a sequence of
events is normally indicative of an earth-directed event with a source
region on the near-side solar disk close to the notional footpoints
of IMF field lines connecting to 1 AU at the event time. However,
EUV images of the low corona from EIT, also onboard SOHO, show no
significant activity whatsoever. Also, during the event the X-ray flux,
as monitored by GOES, was low and decreasing. Thus it seems likely
that the source region was located on the far-side. We speculate
that it was a known active region that had traversed the west limb
a week previously, thus placing it close to central meridian at the
time of event onset. The subsequent activity from this region after
it had traversed the east limb a week later support this picture. We
discuss the nature and timeline of the event in detail, and consider
implications for the generation of particles at 1 AU, particularly in
terms of the fluxes and spectra observed.
Title: A Comparison of CME-associated atmospheric waves observed in
coronal (19.5 nm) and chromospheric (He I 1083 nm and H-alpha 656
nm) lines
Authors: Gilbert, H. R.; Thompson, B. J.; Holzer, T. E.; Burkepile,
J. T.
Bibcode: 2001AGUFMSH12B0746G
Altcode:
Coronal Mass Ejections (CMEs) are frequently associated with wave
phenomena observed in the corona, and sometimes with wave phenomena
observed in the chromosphere. We have studied CME-associated waves
observed in both coronal (19.5 nm) and chromospheric (He I 1083 nm and
H-alpha 656 nm) lines. Comparison of the coronal and chromospheric
signatures allows us to understand better the relationship between
the two wave phenomena.
Title: EIT and SXT Observations of a Quiet-Region Filament Ejection:
First Eruption, Then Reconnection
Authors: Sterling, Alphonse C.; Moore, Ronald L.; Thompson, Barbara J.
Bibcode: 2001ApJ...561L.219S
Altcode:
We observe a slow-onset quiet-region filament eruption with the EUV
Imaging Telescope (EIT) on the Solar Heliospheric Observatory (SOHO)
and the soft X-ray telescope (SXT) on Yohkoh. This event occurred on
1999 April 18 and was likely the origin of a coronal mass ejection
detected by SOHO at 08:30 UT on that day. In the EIT observation,
one-half of the filament shows two stages of evolution: stage 1 is a
slow, roughly constant upward movement at ~1 km s-1 lasting
~6.5 hr, and stage 2 is a rapid upward eruption at ~16 km s-1
occurring just before the filament disappears into interplanetary
space. The other half of the filament shows little motion along the
line of sight during the time of stage 1 but erupts along with the rest
of the filament during stage 2. There is no obvious emission from the
filament in the SXT observation until stage 2; at that time, an arcade
of EUV and soft X-ray loops forms first at the central location of the
filament and then expands outward along the length of the filament
channel. A plot of EUV intensity versus time of the central portion
of the filament (where the postflare loops initially form) shows a
flat profile during stage 1 and a rapid upturn after the start of
stage 2. This light curve is delayed from what would be expected if
``tether-cutting'' reconnection in the core of the erupting region
were responsible for the initiation of the eruption. Rather, these
observations suggest that a loss of stability of the magnetic field
holding the filament initiates the eruption, with reconnection in the
core region occurring only as a by-product.
Title: Three-dimensional numerical simulation of MHD waves observed
by the Extreme Ultraviolet Imaging Telescope
Authors: Wu, S. T.; Zheng, Huinan; Wang, S.; Thompson, B. J.; Plunkett,
S. P.; Zhao, X. P.; Dryer, M.
Bibcode: 2001JGR...10625089W
Altcode:
We investigate the global large amplitude waves propagating across
the solar disk as observed by the SOHO/Extreme Ultraviolet Imaging
Telescope (EIT). These waves appear to be similar to those observed
in Hα in the chromosphere and which are known as
``Moreton waves,'' associated with large solar flares [Moreton,
1960, 1964]. Uchida [1968] interpreted these Moreton waves as the
propagation of a hydromagnetics disturbance in the corona with
its wavefront intersecting the chromosphere to produce the Moreton
wave as observed in movie sequences of Hα images. To
search for an understanding of the physical characteristics of
these newly observed EIT waves, we constructed a three-dimensional,
time-dependent, numerical magnetohydrodynamic (MHD) model. Measured
global magnetic fields, obtained from the Wilcox Solar Observatory
(WSO) at Stanford University, are used as the initial magnetic field
to investigate hydromagnetics wave propagation in a three-dimensional
spherical geometry. Using magnetohydrodynamic wave theory together
with simulation, we are able to identify these observed EIT waves as
fast mode MHD waves dominated by the acoustic mode, called magnetosonic
waves. The results to be presented include the following: (1) comparison
of observed and simulated morphology projected on the disk and the
distance-time curves on the solar disk; (2) three-dimensional evolution
of the disturbed magnetic field lines at various viewing angles;
(3) evolution of the plasma density profile at a specific location
as a function of latitude; and (4) computed Friedrich's diagrams to
identify the MHD wave characteristics.
Title: Eruption and acceleration of flare-associated coronal mass
ejection loops in the low corona
Authors: Neupert, W. M.; Thompson, B. J.; Gurman, J. B.; Plunkett,
S. P.
Bibcode: 2001JGR...10625215N
Altcode:
Observations made by the EUV imaging telescope (EIT) and the Large-Angle
Spectrometric Coronagraph (LASCO) on board the Solar Heliospheric
Observatory (SOHO) have been used to characterize the eruption and
acceleration of flare-associated coronal mass ejections (CMEs) in the
low corona. For three well-observed limb events we tracked CME loops
back to preexisting but faint EUV-emitting loops at heights of 100-250
Mm that initially brightened slowly and possibly increased slowly in
height, apparently in response to filament activity and eruption in the
associated active regions. Subsequent CME acceleration coincided with
a rapid rise of the soft X-ray flux, occurred between 100 and 350 Mm
above the surface, and may have been as high as 0.5 km s-1
s-1, consistent with an impulsive acceleration of the CME
to the speeds observed in subsequent white-light observations. The
existence of a delay of up to 30 min observed between initial filament
eruption in H alpha and subsequent high acceleration of the CME in
one event implies that there may have been two separate phases of
magnetic reconnection, with the initial filament activity acting as
a trigger for subsequent CME and energetic particle acceleration in
the impulsive stage of the flare. The presence or absence of this
impulsive phase may provide a basis for the two types of CMEs that
have been discussed in the literature.
Title: Reconnection remnants in the magnetic cloud of October 18-19,
1995: A shock, monochromatic wave, heat flux dropout, and energetic
ion beam
Authors: Collier, Michael R.; Szabo, A.; Farrell, W. M.; Slavin,
J. A.; Lepping, R. P.; Fitzenreiter, R.; Thompson, B.; Hamilton,
D. C.; Gloeckler, G.; Ho, G. C.; Bochsler, P.; Larson, D.; Ofman, L.
Bibcode: 2001JGR...10615985C
Altcode:
Evidence is presented that the Wind spacecraft observed particle and
field signatures on October 18-19, 1995, due to reconnection near
the foot points of a magnetic cloud (i.e., between 1 and 5 solar
radii). These signatures include (1) an internal shock traveling
approximately along the axis of the magnetic cloud, (2) a simple
compression of the magnetic field consistent with the foot point
magnetic fields being thrust outward at speeds much greater than the
solar wind speed, (3) an electron heat flux dropout occurring within
minutes of the shock, indicating a topological change resulting from
disconnection from the solar surface, (4) a very cold 5 keV proton
beam, and (5) an associated monochromatic wave. We expect that given
observations of enough magnetic clouds, Wind and other spacecraft
will see signatures similar to the ones reported here indicating
reconnection. However, these observations require the spacecraft to
be fortuitously positioned to observe the passing shock and other
signatures and will therefore be associated with only a small fraction
of magnetic clouds. Consistent with this, a few magnetic clouds observed
by Wind have been found to possess internal shock waves.
Title: On-the-Disk Development of the Halo Coronal Mass Ejection on
1998 May 2
Authors: Pohjolainen, S.; Maia, D.; Pick, M.; Vilmer, N.; Khan, J. I.;
Otruba, W.; Warmuth, A.; Benz, A.; Alissandrakis, C.; Thompson, B. J.
Bibcode: 2001ApJ...556..421P
Altcode:
A halo coronal mass ejection (CME) was observed at 15:03 UT on 1998 May
2 by the Solar and Heliospheric Observatory Large-Angle Spectrometric
Coronagraph. The observation of the CME was preceded by a major soft
X-ray flare in NOAA Active Region 8210, characterized by a delta spot
magnetic configuration and some activity in region 8214. A large
transequatorial interconnecting loop (TIL) seen in the soft X-rays
connected AR 8210 to a faint magnetic field region in the periphery
of region 8214. Smaller loop systems were also connecting AR 8210 to
other fainter bipolar magnetic structures, the interconnecting loop
(IL) east of AR 8210 being one of the most visible. We present here
a multiwavelength analysis of the large- and small-scale coronal
structures associated with the development of the flare and of the
CME, with emphasis placed on radio-imaging data. In the early phases
of the flare, the radio emission sources traced the propagation paths
of electrons along the TIL and the IL, which are accelerated in the
vicinity of AR 8210. Furthermore, jetlike flows were observed in soft
X-rays and in Hα in these directions. Significantly, the TIL and
IL loop systems disappeared at least partially after the CME. An EUV
Imaging Telescope (EIT) dimming region of similar size and shape to the
soft X-ray TIL, but noticeably offset from it, was also observed. During
the ``flash'' phase of the flare, new radio sources appeared, presenting
signatures of destabilization and reconnection at discrete locations of
the connecting loops. We interpret these as possible signatures of the
CME liftoff on the disk. An Hα Moreton wave (blast wave) and an ``EIT
wave'' were also observed, originating from the flaring AR 8210. The
signatures in radio, after the wave propagated high into the corona,
include type II-like emissions in the spectra. The radio images link
these emissions to fast-moving sources, presumably formed at locations
where the blast wave encounters magnetic structures. The opening of
the CME magnetic field is revealed by the radio observations, which
show large and expanding moving sources overlying the later-seen EIT
dimming region.
Title: SOHO Observations of a Coronal Mass Ejection
Authors: Akmal, Arya; Raymond, John C.; Vourlidas, Angelos; Thompson,
Barbara; Ciaravella, A.; Ko, Y. -K.; Uzzo, M.; Wu, R.
Bibcode: 2001ApJ...553..922A
Altcode:
We describe a coronal mass ejection (CME) observed on 1999 April 23 by
the Ultraviolet Coronagraph Spectrometer (UVCS), the Extreme-Ultraviolet
Imaging Telescope (EIT), and the Large-Angle and Spectrometric
Coronagraphs (LASCO) aboard the Solar and Heliospheric Observatory
(SOHO). In addition to the O VI and C III lines typical of UVCS spectra
of CMEs, this 480 km s-1 CME exhibits the forbidden and
intercombination lines of O V at λλ1213.8 and 1218.4. The relative
intensities of the O V lines represent an accurate electron density
diagnostic not generally available at 3.5 Rsolar. By
combining the density with the column density derived from LASCO,
we obtain the emission measure of the ejected gas. With the help
of models of the temperature and time-dependent ionization state of
the expanding gas, we determine a range of heating rates required to
account for the UV emission lines. The total thermal energy deposited
as the gas travels to 3.5 Rsolar is comparable to the
kinetic and gravitational potential energies. We note a core of colder
material radiating in C III, surrounded by hotter material radiating
in the O V and O VI lines. This concentration of the coolest material
into small regions may be a common feature of CMEs. This event thus
represents a unique opportunity to describe the morphology of a CME,
and to characterize its plasma parameters.
Title: Solar Phenomena Associated With EIT Waves
Authors: Myers, D. C.; Biesecker, D. A.; Thompson, B. J.; Vourlidas, A.
Bibcode: 2001AGUSM..SH51B03M
Altcode:
Observations with the Extreme Ultraviolet Imaging Telescope (EIT)
on SOHO revealed the existence of transient waves which appear to
propagate across the disk from a localized starting point. These EIT
waves may be the coronal counterpart of previously discovered Moreton
waves. Moreton waves have long been thought to be associated with
solar flares, though this may have been because flares are more easily
observed than other phenomena, such as Coronal Mass Ejections. EIT
waves are observed much more often than Moreton waves, though this
may also be due to detection efficiency. In this study, we hope to
gain a better understanding of EIT waves, and in particular their
initiation, through their relationship to other solar events. This
study uses a complete catalog of EIT waves observed from March, 1997
to June, 1998; a period in which 175 waves were found. For each wave,
the following ancillary data sets were examined for co-temporal and
co-spatial events: GOES X-ray Monitor, LASCO Coronagraph, and Type II
radio burst data. EIT waves are classified according to a system which
measures the reliability of the existence of the event. We investigate
the rate at which each class of EIT wave is associated with flares,
CMEs and Type II events. Data are further divided into limb and disk
events in order to correct for detection efficiency and biases. An
investigation of EUV dimmings is also included as they offer clues to
the relationship between EIT waves, flares and CME's.
Title: Solar source regions of coronal mass ejections and their
geomagnetic effects
Authors: Plunkett, S. P.; Thompson, B. J.; St. Cyr, O. C.; Howard,
R. A.
Bibcode: 2001JASTP..63..389P
Altcode: 2001JATP...63..389P
It is generally accepted that the fast interplanetary manifestations of
coronal mass ejections (ICMEs) are the major solar drivers of many space
weather phenomena, including large, non-recurrent geomagnetic storms
and solar energetic particle events. High-quality synoptic observations
of the solar corona, as carried out by the EIT and LASCO experiments on
SOHO, provide near real-time imaging of CMEs from the base of the corona
out to a projected distance of 30Rsolar (Rsolar is
the solar radius). The average characteristics of CMEs observed by LASCO
are similar to those from earlier coronagraphs. Most CMEs travel with
approximately constant speed through the LASCO field of view. However,
a significant number accelerate as they move outward, and some fast
events have been observed to decelerate. LASCO has observed a great deal
of internal structure in many CMEs. Concave-outward structures that
are interpreted as magnetic flux ropes are observed in approximately
one third of all events. Complex structures are often observed in the
trailing portions of CMEs. Halo CMEs, many of which are very faint,
can be routinely observed with LASCO. Extreme-ultraviolet (EUV)
images of the low corona and solar disk, as recorded by EIT, reveal
a complex web of CME signatures. These include large-scale waves in
the inner corona associated with CMEs, extended regions of depleted
EUV intensity, and bright arcades that form following the occurrence
of a CME. The combination of LASCO and EIT imagery allows the source
regions of halo CMEs to be identified, and can be used to help predict
the occurrence of geomagnetic disturbances several days in advance. The
most important parameters in determining the geoeffectiveness of an
ICME are the magnetic field strength and direction, and the speed of
the disturbance. The most intense geomagnetic storms are associated
with strong and persistent southward fields, either within the ICME
itself or in the compressed sheath of solar wind plasma ahead of it.
Title: An Observational Test for Solar Atmospheric Heating
Authors: van Driel-Gesztelyi, L.; Démoulin, P.; Ireland, J.; Thompson,
B.; Fludra, A.; Oláh, K.; Kövári, Zs.; Harra, L. K.; Mandrini,
C. H.; Bocchialini, K.; Orlando, S.
Bibcode: 2001IAUS..203..514V
Altcode:
We study the evolution of the emissivity and heating correlated with
magnetic observables of an active region from its birth throughout
its decay during seven solar rotations (July-Dec. 1996). Taking one
"snapshot" per g:wq: Command not found. time of flares, we analyse
multi-wavelength and multi-instrument data obtained from SOHO (MDI,
EIT, CDS and SUMER), Yohkoh (SXT), GOES, SOLSTICE and 10.7 cm radio
data from DRAO, Canada. We utilise our results to test the validity
of coronal heating models. We find that models which are based on
the dissipation of stressed, current-carrying magnetic fields are in
better agreement with the observations than the models which attribute
coronal heating to the dissipation of MHD waves.
Title: Magnetic Evolution of a Long-Lived Active Region: The Sources
of Magnetic Helicity
Authors: Mandrini, C. H.; Démoulin, P.; van Driel-Gesztelyi, L.;
Aulanier, G.; Thompson, B.; Plunkett, S.; Kövári, Zs.
Bibcode: 2001ASPC..248..139M
Altcode: 2001mfah.conf..139M
No abstract at ADS
Title: Early life of coronal mass ejections
Authors: Gopalswamy, N.; Thompson, B. J.
Bibcode: 2000JASTP..62.1457G
Altcode: 2000JATP...62.1457G
Coronal mass ejections (CMEs) are large-scale magnetized plasma
structures ejected from closed magnetic field regions of the Sun. White
light coronagraphic observations from ground and space have provided
extensive information on CMEs in the outer corona. However, our
understanding of the solar origin and early life of CMEs is still in
an elementary stage because of lack of adequate observations. Recent
space missions such as Yohkoh and Solar and Heliospheric Observatory
(SOHO) and ground-based radioheliographs at Nobeyama and Nancay have
accumulated a wealth of information on the manifestations of CMEs
near the solar surface. We review some of these observations in
an attempt to relate them to what we already know about CMEs. Our
discussion relies heavily on non-coronagraphic data combined with
coronagraphic data. Specifically, we discuss the following aspects of
CMEs: (i) coronal dimming and global disk signatures, (ii) non-radial
propagation during the early phase, (iii) Photospheric magnetic field
changes during CMEs, and (iv) acceleration of fast CMEs. The relative
positions and evolution of coronal dimming, arcade formation, prominence
eruption will be discussed using specific events. The magnitude and
spatial extent of CME acceleration may be an important parameter that
distinguishes fast and slow CMEs.
Title: Sympathetic flaring with BATSE, GOES, and EIT data
Authors: Biesecker, D. A.; Thompson, B. J.
Bibcode: 2000JASTP..62.1449B
Altcode: 2000JATP...62.1449B
Sympathetic flaring is defined as the initiation of a solar flare
as a result of a transient phenomenon occurring elsewhere on the
Sun. Discovery of sympathetic flaring or lack thereof, may lead to a
greater understanding of the physics of flare initiation. Knowledge of
a mechanism for initiating solar flares would also aid in predicting
at least some solar flares. Two studies of sympathetic flaring
are presented in this paper. The first part of the paper presents
a test for sympathetic flaring in flares observed with the Burst
and Transient Source Experiment. A Monte Carlo simulation is used
to compare the distribution of solar X-ray flares in time to that
expected from a time-varying, Poisson distribution. No evidence for
sympathetic flaring is found, though it cannot be ruled out. The X-ray
flare data also do not allow discovery of sympathetic flares occurring
within 2 min of the initial flare. Because the observations do allow
for at least some flares to occur sympathetically, the second part of
the paper examines one possible mechanism for initiating flares. The
mechanism examined is large-scale coronal transients observed by the
SOHO//Extreme Ultraviolet Imaging Telescope: EIT waves. A comparison of
the rate of flaring in the interval prior to an EIT wave to the rate
of flaring while the wave traverses the solar disk shows no increase
in the number of flares due to the EIT wave.
Title: Measurements of the solar wind over a wide range of
heliocentric distances - a comparison of results from the first
three Whole Sun Months
Authors: Breen, A. R.; Thompson, B. J.; Kojima, M.; Biesecker, D. A.;
Canals, A.; Fallows, R. A.; Linker, J. A.; Lazarus, A. J.; Lecinski,
A.; Mikic, Z.; Moran, P. J.; Williams, P. J. S.
Bibcode: 2000JASTP..62.1527B
Altcode: 2000JATP...62.1527B
Co-ordinated observations of the Sun and inner heliosphere using a
large number of space- and ground-based instruments were carried out
in August-September 1996, August 1998 and August-September 1999 as the
first, second and third Whole Sun Months. These observations provided
unprecedented cover of the Sun and inner heliosphere at solar minimum
(1996) and during the rising phase of the new solar cycle (1998,
1999). In this paper we review the observations made during the three
Whole Sun Months and consider the changes in the large-scale structure
of the heliosphere seen over the four years.
Title: Moreton Waves
Authors: Thompson, B.
Bibcode: 2000eaa..bookE2575T
Altcode:
`Moreton waves', named for the observer who popularized them, are a
solar phenomenon also known in scientific literature as `Moreton-Ramsey
waves', `flare waves', `flare-associated waves', `MHD blast waves',
`chromospheric shock fronts' and various other combinations of terms
which connote violently propagating impulsive disturbances. It is
unclear whether all of the observations to which these t...
Title: Initiation of CMEs: the role of magnetic twist
Authors: van Driel-Gesztelyi, L.; Manoharan, P. K.; Démoulin, P.;
Aulanier, G.; Mandrini, C. H.; Lopez-Fuentes, M.; Schmieder, B.;
Orlando, S.; Thompson, B.; Plunkett, S.
Bibcode: 2000JASTP..62.1437V
Altcode: 2000JATP...62.1437V
Recent multiwavelength observations, modelling results and
theoretical developments indicate the importance of twisted magnetic
configurations in solar active regions (ARs) in the initiation of
coronal mass ejections (CMEs). Through multiwavelength analysis of a
few representative events we make an attempt to provide constraints
for CME models. The two events presented here in detail start with
the expansion of sigmoids (S- or inverse S-shaped loops) observed in
soft X-rays. Both events (on 25 October /1994 and 14 October /1995)
occurred before the launch of the SOHO spacecraft, but indirect
evidences (i.e. signatures of an outward propagation traced up to /~20
solar radii and an associated magnetic cloud) suggest that both of them
were related to CMEs. We show evidence that sigmoids are the coronal
manifestations of twisted magnetic flux tubes, which start expanding
presumably due to a loss of equilibrium. It is noteworthy that the
analysed CMEs occurred in a complex (not simply bipolar) magnetic
environment and in all cases we found evidences of the interaction
(magnetic reconnection) with the surrounding fields. We propose a
scenario for sigmoid expansion related CME events and suggest that
twisted magnetic configurations are good candidates for being source
regions of CMEs.
Title: Abundance variations and fractionation effects in a gradual
SEP event
Authors: Galvin, A. B.; Möbius, E.; Popecki, M. A.; Kistler, L. M.;
Morris, D.; Heirtzler, D.; Hovestadt, D.; Klecker, B.; Bogdanov,
A. T.; Thompson, B.
Bibcode: 2000AIPC..528..127G
Altcode: 2000atep.conf..127G
Using data from the ACE SEPICA experiment, we examine elemental
abundance variations for C, O, Ne, Mg, Si and Fe for the 1998 April
21-23 ``pure'' gradual SEP event in the energy ranges 0.6-0.8 and
0.8-1.0 MeV/nucleon. The high FIP element Ne has SEP abundances
(Ne/O) consistent with nominal photospheric and coronal values. Low
FIP elements Mg, Fe, and Si show enhancements (relative to O) over
both photospheric and coronal abundances. Power law fits to the SEP
abundances (normalized to coronal values) as a function of measured
<Q>/A are performed and evaluated. It is found that for this event
the single-parameter power law assumption does not yield a consistently
good fit. The derived power law index γ varies with both time and
energy. .
Title: Correction to “Coronal dimmings and energetic CMEs in
April-May 1998,”
Authors: Thompson, B. J.; Cliver, E. W.; Nitta, N.; Delannée, C.;
Delaboudinière, J. -P.
Bibcode: 2000GeoRL..27.1865T
Altcode:
No abstract at ADS
Title: SOHO and radio observations of a CME shock wave
Authors: Raymond, John C.; Thompson, Barbara J.; St. Cyr, O. C.;
Gopalswamy, Nat; Kahler, S.; Kaiser, M.; Lara, A.; Ciaravella, A.;
Romoli, M.; O'Neal, R.
Bibcode: 2000GeoRL..27.1439R
Altcode:
A 1200 km s-1 Coronal Mass Ejection was observed with the
SOHO instruments EIT, LASCO and UVCS on June 11, 1998. Simultaneously,
Type II radio bursts were observed with the WAVES experiment aboard
the Wind spacecraft at 4 MHz and by ground-based instruments at metric
wavelengths. The density in the shock wave implied by the higher
frequency is close to that inferred from the SOHO/UVCS experiment. The
drift rates of the Type II radio bursts suggest shock speeds lower than
the speed derived from SOHO observations. The SOHO/UVCS spectrum shows
enhanced emission in lines of O5+ and Si11+,
consistent with modest compression in an MHD shock.
Title: Radio-rich solar eruptive events
Authors: Gopalswamy, N.; Kaiser, M. L.; Thompson, B. J.; Burlaga,
L. F.; Szabo, A.; Lara, A.; Vourlidas, A.; Yashiro, S.; Bougeret,
J. -L.
Bibcode: 2000GeoRL..27.1427G
Altcode:
We report on the analysis of a large number of solar eruptive events
that produced radio emission in the dekameter-hectometric (DH) radio
window (1-14 MHz), newly opened by the Wind/WAVES experiment. The
distinguishing characteristics of coronal mass ejections (CMEs)
associated with the DH type II radio bursts are larger-than-average
width and speed. Flares of all sizes (X-ray importance B to X) occurring
at all longitudes were associated with the DH type II bursts and
CMEs. We found a global enhancement in EUV over an area much larger than
the flaring active region in the beginning many events. A comparison
between the ‘Shock Associated’ events and microwave bursts shows
that at least half of the events do not have temporal relation. A
majority of the DH type II bursts were associated with IP shocks
and kilometric type II bursts. In particular, we found a very close
relationship between the kilometric type II bursts and the IP shocks.
Title: Three-Dimensional Structure of Flux-Rope CME's: Theory and
Observation*
Authors: Krall, J.; Chen, J.; Howard, R. A.; Thompson, B. J.
Bibcode: 2000SPD....31.0801K
Altcode: 2000BAAS...32R.839K
A recent program of direct comparison of model CME results and CME
observations [1-4] has produced a coherent view of the geometry and
the dynamics of a specific class of CME's, which we refer to as
``flux-rope CME's.'' We further support this view by presenting
LASCO/EIT measurements and model results for 11 flux-rope CME
events. Each CME is compared to the theoretical results of a flux rope
model [4,5] under the assumption that the driving mechanism is flux
injection. In all cases the source region for the CME is determined
so as to properly account for projection effects in the model/data
comparisons. This talk will summarize the basic physical understanding
resulting from the recent work. In particular, we discuss observable
signatures produced by the model and compare them with the EIT and
LASCO data. We also discuss photospheric signatures of these events in
terms of motion (a few meters per second) and changes in the tangential
magnetic field (about ten percent for tens of minutes). These are very
small but may be accessible by future observations. Taken as a whole,
the observational and model results provide a consistent view of the
three-dimensional structure of this class of CME's. [1] Chen et al.,
ApJ Lett., 490, L191, 1997. [2] Wood et al, ApJ, 512, 484, 1999. [3]
Chen et al., to appear in ApJ, 2000. [4] Krall et al., to appear in ApJ,
2000. [5] Chen, J., JGR, 101, 27499, 1996. *Work supported by ONR.
Title: Coronal dimmings and energetic CMEs in April-May 1998
Authors: Thompson, B. J.; Cliver, E. W.; Nitta, N.; Delannée, C.;
Delaboudinière, J. -P.
Bibcode: 2000GeoRL..27.1431T
Altcode:
We have analyzed the coronal dimmings for seven fast (> 600 km/s)
coronal mass ejections (CMEs) occurring between 23 April and 9 May which
were associated with flares from NOAA active region (AR) 8210. Each
of these CMEs had at least one group of interplanetary radio bursts
associated with them. These dimming regions were identified by their
strong depletion in coronal EUV emission within a half hour of the
estimated time of CME lift-off. They included areas which were as
dark as quiescent coronal holes as well as other regions with weaker
brightness depletions. While the location of the active region and
the associated flare did not correspond well with the coronagraph
observations, we found that the extended dimming areas in these events
generally mapped out the apparent “footprint” of the CME as observed
by white-light coronagraph. We briefly discuss the implications of
these results on models of CME topology.
Title: SOHO/UVCS Observations of a Coronal Jet During the Third
Whole Sun Month Campaign
Authors: Ko, Y. -K.; Raymond, J.; Gibson, S.; Strachan, L.; Alexander,
D.; Fletcher, L.; Holzer, T.; Gilbert, H.; Burkepile, J.; St. Cyr,
C.; Thompson, B.
Bibcode: 2000SPD....31.0271K
Altcode: 2000BAAS...32R.823K
On August 26 1999, a coronal jet occurred at the north west limb
near a sigmoid active region which has been the target for a joint
observation plan during the third Whole Sun Month Campaign. This jet
was observed by several instruments at the limb (SOHO/CDS, SOHO/EIT,
TRACE, MLSO/CHIP, MLSO/PICS), at 1.7 Ro (SOHO/UVCS), and at the outer
corona (SOHO/LASCO). At 1.7 Ro, the intensities of Lyman alpha, Lyman
beta in the jet increased by as large a factor of 100 compared with the
background corona, while those for O VI 1032 and O VI 1037 increased
by a factor of 2. C III 977 line also brightened significantly. The
line shift in the lines indicates that the line-of-sight velocity in
the jet started from 150 km/sec blue shift and ended at 120 km/sec
red shift. This line-of-sight motion seen at 1.7 Ro apparently was
opposite that observed when the jet emerged from the limb. In this
paper, we present the observation by SOHO/UVCS and discuss the dynamic
structure and physical properties of this jet as it passed through
1.7 Ro. Comparisons will be shown with the observations from other
instruments. This work is supported by NASA Grant number NAG5-7822.
Title: The Third Whole Sun Month Campaign - Coronal Synoptic Maps
Authors: Biesecker, D. A.; Gibson, S. E.; Alexander, D.; Fludra, A.;
Hoeksema, J. T.; Panasyuk, A. V.; Thompson, B. J.
Bibcode: 2000SPD....31.0239B
Altcode: 2000BAAS...32..817B
Observations for the Third Whole Sun Month Campaign were made throughout
Carrington Rotation 1953 (August 18-September 14, 1999). As in the
first campaign; the primary focus is on understanding the large scale
solar corona and the connections to interplanetary space over a full
solar rotation. The fundamental notion of these campaigns is that the
observations are available for anyone to work with. In this poster,
we use synoptic maps to show the morphology of the solar corona during
CR1953 at a variety of wavelengths, heights, and temperatures. Data
are shown from YOHKOH SXT, MLSO Mk4, and SOHO MDI, CDS, UVCS, EIT,
and LASCO. The current campaign differs from the first campaign in that
near solar maximum conditions prevailed. We held one workshop in order
to get organized and begin collaborations. The planned studies will
include determining the plasma parameters in various coronal structures
and in modeling the structure of the coronal magnetic fields. In
addition, we had the opportunity to study how a "sigmoidal" active
region evolved as it crossed the solar disk and affected the global
corona through a series of flares and eruptive events, and to obtain
detailed observations of its structure over a wide range of heights
and temperatures. We will be holding future workshops to analyze the
data and work on models. We invite you to participate in this campaign
or at least see our current plans for data analysis and modeling.
Title: Solar Phenomena Associated With EIT Waves
Authors: Myers, D. C.; Biesecker, D. A.; Vourlidas, A.; Thompson, B. J.
Bibcode: 2000SPD....31.0273M
Altcode: 2000BAAS...32..824M
In an effort to understand what causes an "EIT wave" or what effects
an EIT wave might have, we are investigating whether EIT waves
can be associated directly with any other solar phenomena. An EIT
wave is a coronal disturbance, typically appearing as a bright rim,
observed to propagate across the Sun. Waves at the solar limb are
identified by the deflections of magnetic fields that they cause. We
have taken a working catalogue of "EIT waves" and determined what,
if any, solar phenomena are associated with each wave. We have thus
far looked for an association with GOES X-ray flares and with LASCO
coronal mass ejections. This poster shows the work accomplished thus
far, in particular, that there is a strong association with GOES flux
increases and that waves with a higher quality rating tend to have
a higher GOES flux level. We also plan to determine if there is an
association with radio transients, particularly type II events. The
EIT wave catalogue was compiled by examining EIT difference images of
the Sun from the start of higher cadence images (24-March-1997). Each
wave is classified by a quality rating from 0 to 6. The quality rating
describes a confidence level that the given times contain an EIT wave,
with 0 being the lowest certainty and 6 the highest. The catalogue of
EIT waves, and this study, are still being expanded and will eventually
encompass all EIT waves observed with a high image cadence from 1996
through 1998.
Title: Max Millennium/Whole Sun Month Observations of a Sigmoid Region
(AR 8668)
Authors: Zarro, D. M.; Canfield, R. C.; Nitta, N.; Myers, D. C.;
Gregory, S. E.; Qiu, J.; Alexander, D.; Hudson, H. S.; Thompson,
B. J.; LaBonte, B. J.
Bibcode: 2000SPD....31.0236Z
Altcode: 2000BAAS...32..817Z
We report on observations of a sigmoidal region AR 8668 obtained
during the Whole Sun Month #3 campaign and Max Millennium Coordinated
Observing Program #2. The observations pertain to the period 1999
August 16-17 during which several GOES B and C class flares occurred
in AR 8668. Near simultaneous observations were obtained by SOHO (EIT
195 Angstroms/ and MDI full-disk magnetograms), TRACE 171 Angstroms/,
Yohkoh SXT, Big Bear (Hα ), and Mees (IVM vector magnetograms). The
multi-wavelength nature of these data, combined with their overlapping
spatial and temporal coverages, provide a unique opportunity to study
the magnetic topology and flaring evolution of twisted flux structures
associated with sigmoids. An objective of this study is to co-align
images and magnetograms obtained before and during the observed flares,
and compare the results with inferences from the topological model of
Titov and Demoulin, A&A 351, 707 (1999). We will present examples
of these coalignments and identify sites of magnetic energy release
that are associated with topological features (e.g. separatrices)
predicted by this model.
Title: Observations of the 24 September 1997 Coronal Flare Waves
Authors: Thompson, B. J.; Reynolds, B.; Aurass, H.; Gopalswamy, N.;
Gurman, J. B.; Hudson, H. S.; Martin, S. F.; St. Cyr, O. C.
Bibcode: 2000SoPh..193..161T
Altcode:
We report coincident observations of coronal and chromospheric `flare
wave' transients in association with a flare, large-scale coronal
dimming, metric radio activity and a coronal mass ejection. The two
separate eruptions occurring on 24 September 1997 originate in the
same active region and display similar morphological features. The
first wave transient was observed in EUV and Hα data, corresponding
to a wave disturbance in both the chromosphere and the solar corona,
ranging from 250 to approaching 1000 km s−1 at different
times and locations along the wavefront. The sharp wavefront had a
similar extent and location in both the EUV and Hα data. The data did
not show clear evidence of a driver, however. Both events display a
coronal EUV dimming which is typically used as an indicator of a coronal
mass ejection in the inner corona. White-light coronagraph observations
indicate that the first event was accompanied by an observable coronal
mass ejection while the second event did not have clear evidence of a
CME. Both eruptions were accompanied by metric type II radio bursts
propagating at speeds in the range of 500-750 km s−1,
and neither had accompanying interplanetary type II activity. The
timing and location of the flare waves appear to indicate an origin
with the flaring region, but several signatures associated with coronal
mass ejections indicate that the development of the CME may occur in
concert with the development of the flare wave.
Title: Structure of a Large low-Latitude Coronal Hole
Authors: Bromage, B. J. J.; Alexander, D.; Breen, A.; Clegg, J. R.;
Del Zanna, G.; DeForest, C.; Dobrzycka, D.; Gopalswamy, N.; Thompson,
B.; Browning, P. K.
Bibcode: 2000SoPh..193..181B
Altcode:
Coronal holes on the Sun are the source of high-speed solar wind
streams that produce magnetic disturbances at the Earth. A series
of multi-wavelength, multi-instrument observations obtained during
the 1996 `Whole Sun Month' campaign examined a large coronal hole in
greater detail than ever before. It appeared on the Sun in August, and
extended from the north pole to a large active region in the southern
hemisphere. Its physical and magnetic structure and subsequent evolution
are described.
Title: Relationship of halo coronal mass ejections, magnetic clouds,
and magnetic storms
Authors: Webb, D. F.; Cliver, E. W.; Crooker, N. U.; Cry, O. C. St.;
Thompson, B. J.
Bibcode: 2000JGR...105.7491W
Altcode:
Halo coronal mass ejections (CMEs) had been rarely reported in
coronagraph observations of the Sun before the Solar and Heliospheric
Observatory (SOHO) mission. Since mid-1996, however, the SOHO Large
Angle Spectrometric Coronagraph (LASCO) instruments have observed many
halo or partial-halo CMEs. A halo CME, especially when associated
with solar activity near sun center, is important for space weather
concerns because it suggests the launch of a potentially geoeffective
disturbance toward Earth. During the post-solar minimum period from
December 1996 to June 1997, we found that all six halo CMEs that were
likely Earthward-directed were associated with shocks, magnetic clouds,
and moderate geomagnetic storms at Earth 3-5 days later. The results
imply that magnetic cloud-like structures are a general characteristic
of CMEs. Most of the storms were driven by strong, sustained southward
fields either in the magnetic clouds, in the post-shock region,
or both. We discuss the characteristics of the halo events observed
during this period, their associated signatures near the solar surface,
and their usefulness as predictors of space weather at Earth.
Title: Yohkoh SXT and SOHO EIT Observations of Sigmoid-to-Arcade
Evolution of Structures Associated with Halo Coronal Mass Ejections
Authors: Sterling, Alphonse C.; Hudson, Hugh S.; Thompson, Barbara J.;
Zarro, Dominic M.
Bibcode: 2000ApJ...532..628S
Altcode:
A subset of the solar-disk counterparts to halo coronal mass ejections
(CMEs) displays an evolution in soft X-rays (SXR) that is characterized
by a preflare S-shaped structure, dubbed a ``sigmoid,'' which evolves
into a postflare cusp or arcade. We examine the morphological properties
of the evolution of sigmoids into cusps and arcades for four such
regions associated with SXR flares, using the Soft X-Ray Telescope
(SXT) on the Yohkoh satellite and the EUV Imaging Telescope (EIT) on
the Solar and Heliospheric Observatory (SOHO) satellite. Most of our
EIT observations are with the 1.5 MK 195 Å Fe XII channel. At most,
there is only a weak counterpart to the SXR sigmoid in the preflare 195
Å EUV images, indicating that the preflare sigmoid has a temperature
greater than 1.5 MK. While more identifiable than in the 195 Å channel,
a clear preflare sigmoid is also not observed in the 2.0 MK EIT 284 Å
Fe XV channel. During the time of the flare, however, an EUV sigmoid
brightens near the location of the SXR preflare sigmoid. Initially
the SXR sigmoid lies along a magnetic neutral line. As the SXR flare
progresses, new field lines appear with orientation normal to the
neutral line and with footpoints rooted in regions of opposite polarity;
these footpoints are different from those of the preflare sigmoid. The
cusp structures in SXRs develop from these newly ignited field lines. In
EIT images, the EUV sigmoid broadens as the flare progresses, forming
an arcade beneath the SXR cusp. Our findings are consistent with a
standard picture in which the origin of the flare and CME is caused by
the eruption of a filament-like feature, with the stretching of field
lines producing a cusp. We infer that the cusp-producing fields may
be overlying the sigmoid fields in the preflare phase, but we do not
directly observe such preflare overlying fields.
Title: Catalogue of the 1997 SOHO-EIT coronal transient waves and
associated type II radio burst spectra
Authors: Klassen, A.; Aurass, H.; Mann, G.; Thompson, B. J.
Bibcode: 2000A&AS..141..357K
Altcode:
We compare the coronal transient wave phenomenon discovered by SOHO
extreme ultraviolet observations (``EIT waves'') with the associated
radio signature of a coronal shock wave (type II burst). 90% of the
type II bursts are associated with an EIT wave. On average, the speed
derived from the radio burst is about three times larger than the EIT
wave speed. Within the sample, there is no correlation between the
speeds of both tracers of a coronal disturbance. Under very general
assumptions we conclude that both wave phenomena can be different
signatures of the same fast magnetosonic disturbance.
Title: Large-Scale Evolution of the Active Region NOAA 7978, 7981,
7986 Observed by Goes, Soho, and Yohkoh
Authors: Orlando, S.; Khan, J.; van Driel-Gesztelyi, L.; Thompson,
B.; Fludra, A.; Foing, B.
Bibcode: 2000AdSpR..25.1913O
Altcode:
We took part in a joint project aimed to study the large-scale
evolution of an active region from its emergence throughout its decay
for several solar rotations. Our interest focuses on the understanding
of how energy is generated, released, deposited, and transformed in
active regions. To this end, we determined physical parameters like
intensity, temperature, and emission measure of the whole active region
as a function of time for the entire period selected. We present the
preliminary results of the analysis of GOES (Geosynchronous Operational
Environmental Satellite), SOHO (Solar and Heliospheric Observatory)
and Yohkoh data of the active region named NOAA 7978, 7981, and 7986
observed between July and October 1996
Title: Properties of coronal mass ejections: SOHO LASCO observations
from January 1996 to June 1998
Authors: St. Cyr, O. C.; Plunkett, S. P.; Michels, D. J.; Paswaters,
S. E.; Koomen, M. J.; Simnett, G. M.; Thompson, B. J.; Gurman, J. B.;
Schwenn, R.; Webb, D. F.; Hildner, E.; Lamy, P. L.
Bibcode: 2000JGR...10518169S
Altcode: 2000JGR...105.8169S; 2000JGRA..105.8169S
We report the properties of all the 841 coronal mass ejections (CMEs)
observed by the Solar and Heliospheric Observatory (SOHO) Large Angle
Spectroscopic Coronagraph (LASCO) C2 and C3 white-light coronagraphs
from January 1996 through June 1998, and we compare those properties to
previous observations by other similar instruments. Both the CME rate
and the distribution of apparent locations of CMEs varied during this
period as expected based on previous solar cycles. The distribution
of apparent speeds and the fraction of CMEs showing acceleration were
also in agreement with earlier reports. The pointing stability provided
by an L-1 orbit and the use of CCD detectors have resulted in superior
brightness sensitivity for LASCO over earlier coronagraphs; however, we
have not detected a significant population of fainter (i.e., low mass)
CMEs. The general shape of the distribution of apparent sizes for LASCO
CMEs is similar to those of earlier reports, but the average (median)
apparent size of 72° (50°) is significantly larger. The larger
average apparent size is predominantly the result of the detection of
a population of partial and complete halo CMEs, at least some of which
appear to be events with a significant longitudinal component directed
along the Sun-Earth line, either toward or away from the Earth. Using
full disk solar images obtained by the Extreme ultraviolet Imaging
Telescope (EIT) on SOHO, we found that 40 out of 92 of these events
might have been directed toward the Earth, and we compared the timing
of those with the Kp geomagnetic storm index in the days following
the CME. Although the ``false alarm'' rate was high, we found that 15
out of 21 (71%) of the Kp>=6 storms could be accounted for as SOHO
LASCO/EIT frontside halo CMEs. If we eliminate three Kp storms that
occurred following LASCO/EIT data gaps, then the possible association
rate was 15 out of 18 (83%).
Title: Interplanetary Scintillation Measurements of the Solar Wind
Above Low-Latitude Coronal Holes
Authors: Breen, A. R.; Moran, P. J.; Williams, P. J. S.; Lecinski,
A.; Thompson, B. J.; Harra-Murnion, L. K.; Mikic, Z.; Linker, J. A.
Bibcode: 2000AdSpR..26..789B
Altcode:
Observations of interplanetary scintillation (IPS) made using the EISCAT
facility provide accurate measurements of solar wind velocity between 15
and 120 solar radii. In this paper we present observations of the solar
wind at low latitudes made between 1994 and 1997. Of 178 observations
of the solar wind at low heliographic latitudes, 112 showed evidence of
flow velocities significantly faster than the normal slow wind across a
portion of the ray-path. In all cases, these enhanced flow speeds were
clearly associated with coronal holes extending towards or across the
heliographic equator. Fast flow from very close to the heliographic
equator is clearly associated with equator-crossing coronal holes in
all cases, suggesting that discrete streams of fast wind observed at
low latitudes originate exclusively in coronal holes
Title: Energetic Particle Signatures of a Corotating Interaction
Region from a High Latitude Coronal Hole: SOHO, Wind and Ulysses
Observations
Authors: Posner, A.; Bothmer, V.; Kunow, H.; Gosling, J. T.; Heber,
B.; Lazarus, A. J.; Linker, J. A.; Marsden, R. G.; Mikić, Z.;
Müller-Mellin, R.; Sanderson, T. R.; Szabo, A.; Thompson, B. J.
Bibcode: 2000AdSpR..26..865P
Altcode:
In mid 1996 the Comprehensive Suprathermal and Energetic Particle
Analyser (COSTEP) onboard the Solar and Heliospheric Observatory, at
1 AU in the ecliptic plane, detected recurrent periods of enhanced
MeV ions in association with a corotating interaction region
(CIR). Measurements of energetic ions from the Cosmic Ray and Solar
Particle Instrument/Low Energy Telescope (COSPIN/LET) onboard Ulysses
taken at 5 AU, at mid-northern heliographic latitudes, showed that
Ulysses encountered recurrent particle events during the same time
period. We used the solar wind speeds observed at both locations to
estimate the cor-responding solar source longitudes of the particle
events. These longitudes are related to warps of the Sun's large high
latitude northern coronal hole boundaries observed by SOHO's Extreme
Ultraviolet Imaging Telescope (EIT). The findings are supported
by threedimensional magnetohydrodynamic (MHD) calculations of the
footpoint positions of the magnetic field lines at both spacecraft. The
observations suggest that close to the Sun a superradial expansion of
the fast solar wind from the Sun's high latitude northern coronal hole
down to ecliptic latitudes is present
Title: Solar and Heliospheric Observatory Observations of a Helical
Coronal Mass Ejection
Authors: Ciaravella, A.; Raymond, J. C.; Thompson, B. J.; van
Ballegooijen, A.; Strachan, L.; Li, J.; Gardner, L.; O'Neal, R.;
Antonucci, E.; Kohl, J.; Noci, G.
Bibcode: 2000ApJ...529..575C
Altcode:
The EUV Imaging Telescope (EIT), Large Angle Spectrometric Coronagraph
(LASCO), and Ultraviolet Coronagraph Spectrometer (UVCS) instruments
aboard the SOHO satellite observed a prominence eruption (coronal mass
ejection) on 1997 December 12. Ejected plasma moved at about 130 km
s-1 in the plane of the sky and showed Doppler shifts between
-350 and +30 km s-1. The eruption appeared as a strongly
curved arch in EIT images low in the corona. Emission in ions ranging
from Si III to O VI in the UVCS spectra indicates a temperature range
between 104.5 and 105.5 K. The morphology of the
bright emission regions seen by all three instruments suggests several
strands of a helical structure of moderate pitch angle. A reasonable
fit to the spatial structure and the velocity evolution measured by
UVCS is provided by a left-handed helix untwisting at a rate of about
9×10-4 radians s-1.
Title: Comparisons of Interplanetary Scintillation and Optical
Measurements of Solar Wind Acceleration with Model Results
Authors: Breen, A. R.; de Forest, C. F.; Thompson, B. J.; McKenzie,
J. F.; Modigliani, A.; Moran, P. J.; Williams, P. J. S.
Bibcode: 2000AdSpR..26..781B
Altcode:
Observations of the fast, high latitude solar wind show that
acceleration of the fast wind is complete by 10 solar radii (R),
while measurements from the LASCO instrument on SOHO show that most
of the acceleration takes place inside 5 R. A series of observations
were made in September 1997 using EISCAT and the C2 and C3 coronagraphs
aboard SOHO to measure the solar wind velocity profile from 3 R out to
beyond 30 R. The overlapping fields of view of the instruments allowed
direct comparisons to be made between IPS and optical estimations of
flow velocity. Together, these measurements provide strong constraints
on any model seeking to provide an explanation of the acceleration of
the fast solar wind. We present the results of a comparison between
out observations and the most recent version of the Lindau-Warsaw
solar wind acceleration model
Title: Multi-wavelength Signatures of Coronal Mass Ejection
Authors: Gopalswamy, N.; Yashiro, S.; Kaiser, M. L.; Thompson, B. J.;
Plunkett, S.
Bibcode: 1999spro.proc..207G
Altcode:
We report on the near-surface and outer coronal manifestations of the
1998 January 25 coronal mass ejection (CME) using white light, EUV,
X-ray and hectometric radio data which reveal the three dimensional
structure and long term evolution of the CME. We find that (i) the
substructures of the CME (prominence core, cavity, frontal structure
and the arcade formation) are clearly observed in X-ray and EUV
wavelengths. (ii) The filament heats up early on and is observed as
a backbone in X-rays. (iii) The filament also expands considerably
as it erupts. (iv) The CME is observed through direct leading edge
signature as well as through dimming process in X-rays and in EUV.
Title: Observations of a Propagating Disturbance in TRACE
Authors: Wills-Davey, M. J.; Thompson, B. J.
Bibcode: 1999SoPh..190..467W
Altcode:
TRACE observations from 13 June 1998 in 171 and 195 Å wavelengths show
a propagating disturbance, initiated near the origin of a C-class
flare. The wave moves through and disrupts diffuse, overarching
coronal loops. Only these overlying structures are affected by the
wave; lower-lying coronal structures are unperturbed. The front
does not appear in contemporaneous Lyman-α observations. The
disturbance creates two types of displacement: (1) that of the wave
front itself, and (2) those of large anchored magnetic structures,
which `bob' due to the wave and show transverse velocities an order
of magnitude smaller than those of the front. Comparisons between
the 171 and 195 Å data show that the front appears differently at
different temperatures. Observations in 171 Å (approx. 0.95 MK)
show strong displacement of individual magnetic structures, while 195
Å (approx. 1.4 MK) data reveals a strong wave front and associated
dimming but resolve much less structural motion. There is also strong
evidence of heating in the material engulfed by the wave front,
and comparisons of the 171 and 195 Å data allow us to constrain the
temperature of the plasma through which the wave is propagating to
1-1.4 MK. Examination of the trajectories and velocities of points
along the front suggests that the disturbance is Alfvénic in nature
but contains a compressive component. This is best explained by a
fast-mode magnetoacoustic wave. A comparison of the motion of anchored
structures to that of the wave front gives a constraint on pulse
width. Comparisons with contemporaneous SOHO-EIT full-disk 195 Å
data show evidence that the disturbance is contained within a set of
transequatorial field lines, such that it propagates from a southern
active region to a northern one with no extensive motion to the east
or west. The associated transequatorial loops display residual motion
for about a hour after they are initially disturbed. These results,
coupled with the deflection of wave trajectories, lead us to speculate
on field strength differences between the transequatorial loops and
the region in the TRACE field of view.
Title: Coronal magnetic field topology and source of fast solar wind
Authors: Guhathakurta, M.; Sittler, E.; Fisher, R.; McComas, D.;
Thompson, B.
Bibcode: 1999GeoRL..26.2901G
Altcode:
We have developed a steady state, 2D semi-empirical MHD model of the
solar corona and the solar wind with many surprising results. This
model for the first time shows, that the boundary between the fast
and the slow solar wind as observed by Ulysses beyond 1 AU, is
established in the low corona. The fastest wind observed by Ulysses
(680-780 km/s) originates from the polar coronal holes at 70°-90°
latitude at the Sun. Rapidly diverging magnetic field geometry accounts
for the fast wind reaching down to a latitude of ±30° at the orbit
of Earth. The gradual increase in the fast wind observed by Ulysses,
with latitude, can be explained by an increasing field strength towards
the poles, which causes Alfvén wave energy flux to increase towards
the poles. Empirically, there is a direct relationship between this
gradual increase in wind speed and the expansion factor, f, computed
at r >20R⊙. This relationship is inverse if f is computed very
close to the Sun.
Title: Coronal Transient Waves and Coronal Shock Waves
Authors: Mann, G.; Aurass, H.; Klassen, A.; Estel, C.; Thompson, B. J.
Bibcode: 1999ESASP.446..477M
Altcode: 1999soho....8..477M
Coronal transient (or EIT) waves have been discovered by the EIT
instrument aboard the SOHO spacecraft as a global wave phenomenon in
the low corona. Most of them are associated with solar type II radio
bursts appearing predominantly in the radio frequency range 40-100
MHz. Such type II radio bursts are signatures of shock waves travelling
outwards in the upper corona. The mean EIT wave velocity of 290 km/s
is well above the sound speed in the corona. Therefore, these waves are
considered as fast magnetosonic waves propagating nearly perpendicular
to the ambient magnetic field in the low corona. On the other hand,
the type II burst related shock waves have mean velocities of 970
km/s, which must be well above the local Alfven speed. Considering
both phenomena, i.e., coronal transient waves and type II burst
related shock waves, to be caused by the same initial energy release
(flare), these waves can be used as diagnostic tools for the magnetic
field in the solar corona. Thus, a magnetic field strength of about
5 G is deduced from the EIT wave speeds at 0.08 solar radii above the
photosphere. Such values are well expected above nonactive regions in
the low corona. In the upper corona, i.e., at 0.5 solar radii above
the photosphere, typical magnetic field strengths of about 2.5 G are
deduced from the measurements. This value corresponds to a typical
Alfven speed of 600-1000 km/s, which is well below the type II related
shock speeds as expected.
Title: Long-Term Evolution Of Emissivity And Heating In A Solar
Active Region
Authors: van Driel-Gesztelyi, L.; Thompson, B.; Démoulin, P.; Orlando,
S.; Bocchialini, K.; Oláh, K.; Kövári, Z.; Deforest, C.; Khan,
J.; Fludra, A.; Mandrini, C.
Bibcode: 1999ESASP.446..663V
Altcode: 1999soho....8..663V
We study the evolution of the heating and emissivity of an active
region from its birth throughout its decay during six solar rotations
(July-Nov. 1996). We analyse multi-wavelength and multi-instrument
data obtained from SOHO (EIT, SUMER, CDS, MDI), Yohkoh (SXT), GOES
and 10.7cm radio data from DRAO, Canada. We take one "snapshot" per
rotation at the time of the central meridian passage (CMP) of the
AR, outside of time of flares, which appears to be representative
enough to allow us to make some general conclusions about the
long-term evolution. Deriving physical parameters like intensity
(flux), temperature and emission measure of the entire AR vs. time,
we formulate mathematically the change in radiation emitted by the
decaying AR at several wavelengths. Combining the emissivity data with
the evolution of magnetic flux density as the flux is being dispersed
by small- and larger-scale convective motions, we make an attempt to
understand the physics behind the emission and heating. We also analyse
the effects of flaring on the heating of the AR, and study whether and
how the flare properties evolve during the life of the active region.
Title: Long-Term Magnetic Evolution of an AR and its CME Activity
Authors: van Driel-Gesztelyi, L.; Mandrini, C. H.; Thompson, B.;
Plunkett, S.; Aulanier, G.; Démoulin, P.; Schmieder, B.; de Forest, C.
Bibcode: 1999ASPC..184..302V
Altcode:
Using SOHO/MDI full-disc magnetic maps, we follow the magnetic
evolution of a solar active region for several months in the period of
July-November 1996. We extrapolate the photospheric magnetic fields in
the linear force-free approximation and match the modelled field lines
with the soft X-ray loops observed with the Yohkoh/SXT in order to
diagnose the coronal magnetic shear. We find that while the turbulent
motions diffuse the flux, the differential rotation, and possibly
twisted flux emergence, increase the magnetic shear. Flares are observed
during the first three rotations, while CME events (observed by SOHO/EIT
and LASCO) originate from this AR from its emergence throughout its
decay. Several early CMEs, while none of the late CMEs, are related to
flare events above the GOES B1 level. We find that the late CMEs occur
when the magnetic shear, after accumulating for four rotations, reaches
a high level and saturates. We propose that CME activity serves as a
valve through which the AR could get rid of excess shear and helicity.
Title: SOHO EIT Observations of Extreme-Ultraviolet ``Dimming''
Associated with a Halo Coronal Mass Ejection
Authors: Zarro, Dominic M.; Sterling, Alphonse C.; Thompson, Barbara
J.; Hudson, Hugh S.; Nitta, Nariaki
Bibcode: 1999ApJ...520L.139Z
Altcode:
A solar flare was observed on 1997 April 7 with the Soft X-ray Telescope
(SXT) on Yohkoh. The flare was associated with a ``halo'' coronal
mass ejection (CME). The flaring region showed areas of reduced soft
X-ray (SXR) brightness--``dimmings''--that developed prior to the CME
observed in white light and persisted for several hours following the
CME. The most prominent dimming regions were located near the ends of
a preflare SXR S-shaped (sigmoid) feature that disappeared during the
event, leaving behind a postflare SXR arcade and cusp structure. Based
upon these and similar soft X-ray observations, it has been postulated
that SXR dimming regions are the coronal signatures (i.e., remnants)
of magnetic flux ropes ejected during CMEs. This Letter reports
new observations of coronal dimming at extreme-ultraviolet (EUV)
wavelengths obtained with the Extreme-ultraviolet Imaging Telescope
(EIT) on the Solar and Heliospheric Observatory (SOHO). A series of
EIT observations in the 195 Å Fe XII wavelength band were obtained
simultaneously with SXT during the 1997 April 7 flare/CME. The EIT
observations show that regions of reduced EUV intensity developed at
the same locations and at the same time as SXR dimming features. The
decrease in EUV intensity (averaged over each dimming region) occurred
simultaneously with an increase in EUV emission from flaring loops in
the active region. We interpret these joint observations within the
framework of flux-rope eruption as the cause of EUV and SXR coronal
dimmings, and as the source of at least part of the CME.
Title: The Three-dimensional Coronal Magnetic Field during Whole
Sun Month
Authors: Gibson, S. E.; Biesecker, D.; Guhathakurta, M.; Hoeksema,
J. T.; Lazarus, A. J.; Linker, J.; Mikic, Z.; Pisanko, Y.; Riley, P.;
Steinberg, J.; Strachan, L.; Szabo, A.; Thompson, B. J.; Zhao, X. P.
Bibcode: 1999ApJ...520..871G
Altcode:
Combining models and observations, we study the three-dimensional
coronal magnetic field during a period of extensive coordinated
solar observations and analysis known as the Whole Sun Month (WSM)
campaign (1996 August 10-September 8). The two main goals of the WSM
campaign are addressed in this paper, namely, (1) to use the field
configuration to link coronal features observed by coronagraphs and
imaging telescopes to solar wind speed variations observed in situ and
(2) to study the role of the three-dimensional coronal magnetic field
in coronal force balance. Specifically, we consider how the magnetic
field connects the two fastest wind streams to the two regions that
have been the main foci of the WSM analysis: the equatorial extension
of the north coronal hole (known as the Elephant's Trunk) and the
axisymmetric streamer belt region on the opposite side of the Sun. We
then quantitatively compare the different model predictions of coronal
plasma and solar wind properties with observations and consider the
implications for coronal force balance and solar wind acceleration.
Title: On the Origin of Impulsive Electron Events Observed at 1 AU
Authors: Krucker, Säm; Larson, Davin E.; Lin, Robert P.; Thompson,
Barbara J.
Bibcode: 1999ApJ...519..864K
Altcode:
A statistical survey of 12 impulsive electron events detected
at energies down below 1 keV and 58 events detected above 25
keV observed at 1 AU by the 3-D Plasma and Energetic Particles
experiment on the Wind spacecraft is presented. Timing analysis of the
velocity dispersion reveals two different kinds of electron events:
(1) events released from the Sun at the onset of a radio type III
burst, which suggest that these electrons are part of the population
producing the type III radio emission; and (2) events in which the
electrons are released up to half an hour later than the onset of
the type III burst. These electrons therefore may be produced by a
different acceleration mechanism than the population producing the
radio emission. Both types of behavior can be observed during the
same impulsive electron event at different energies, but most events
show the same timing at all energies. At lower energies (<25 keV),
type III-related impulsive electron events are more often observed
(nine of 12 events), whereas at higher energies (>25 keV), events
not related to type III bursts are more numerous (41 of 58). However,
events of both classes are observed below 1 keV. Impulsive electron
events not related to type III radio bursts are observed to be proton
rich, with an order-of-magnitude lower electron-to-proton ratio than
events related to type III bursts. For roughly 3/4 of the events
not related to type III bursts, large-scale coronal transient waves,
also called EIT waves or coronal Moreton waves, are observed by the
Extreme Ultraviolet Imaging Telescope (EIT) on board SOHO. Temporal
and spatial correlations together with hydromagnetic simulations show
that at least some impulsive electron events are more likely related
to the propagating Moreton wave than to the flare phenomenon itself.
Title: Is the chromosphere hotter in coronal holes?
Authors: Gopalswamy, N.; Shibasaki, K.; Thompson, B. J.; Gurman,
J. B.; Deforest, C. E.
Bibcode: 1999AIPC..471..277G
Altcode: 1999sowi.conf..277G
Coronal holes are brighter than the quiet Sun in microwaves. Microwave
emission from the quiet Sun is optically thick thermal bremsstrahlung
from the upper chromosphere. Therefore, the optically thick layer in the
coronal hole chromosphere must be hotter than the corresponding layer
in the quiet chromosphere. We present microwave and SOHO observations
in support of this idea. Because of the availability of simultaneous
EUV and microwave images it is now possible to obtain more details
of this enigmatic phenomenon. In this paper, we highlight the primary
properties of the microwave enhancement in coronal holes and point out
some related phenomena. Finally, we summarize the possible explanations
of the radio enhancement.
Title: Large-scale structure and coronal dynamics from joint radio,
SOHO/EIT and coronagraph observations
Authors: Pick, M.; Maia, D.; Vourlidas, A.; Benz, A. O.; Howard, R.;
Thompson, B. J.
Bibcode: 1999AIPC..471..649P
Altcode: 1999sowi.conf..649P
This study presents joint observations of an `halo' coronal mass
ejection from the EIT telescope and LASCO coronagraphs on SOHO, from
the Nançay Radioheliograph (NRH) and the Zurich ETH radiospectrograph
(Phoenix-2). This event includes different manifestations: a coronal
wave and a dimming region detected by EIT, a CME showing bright discrete
portions above east and west limbs. Radio signatures of all these
manifestations are found and the interpretation is briefly discussed.
Title: SOHO/EIT Observations of the 1997 April 7 Coronal Transient:
Possible Evidence of Coronal Moreton Waves
Authors: Thompson, B. J.; Gurman, J. B.; Neupert, W. M.; Newmark,
J. S.; Delaboudinière, J. -P.; Cyr, O. C. St.; Stezelberger, S.;
Dere, K. P.; Howard, R. A.; Michels, D. J.
Bibcode: 1999ApJ...517L.151T
Altcode:
We report observations obtained with the Extreme ultraviolet
Imaging Telescope (EIT) on board SOHO of a large-scale coronal
transient propagating across the disk of the Sun at a speed of 250 km
s-1, in apparent association with a flare and coronal mass
ejection. The observations consist of a series of images taken in the
Fe XII 195 Å bandpass at an average cadence of 15 minutes. A visible
increase in coronal emission propagates away from the erupting region,
traveling across most of the solar disk in less than an hour. As the
wave propagates through the ambient corona, its path is not homogeneous,
and it is less observable near strong magnetic features such as
active regions and magnetic neutral lines. The characteristics of
this event appear to be representative of several other ``EIT waves,''
which we identify as strong candidates for the coronal manifestation
of Moreton waves.
Title: Modeling CMEs in three dimensions using an analytic MHD model
Authors: Gibson, Sarah E.; Alexander, David; Biesecker, Doug; Fisher,
Richard; Guhathakurta, Madhulika; Hudson, Hugh; Thompson, B. J.
Bibcode: 1999AIPC..471..645G
Altcode: 1999sowi.conf..645G
Because coronal mass ejections (CMEs) are viewed in projection,
it is difficult to determine their three-dimensional nature. We use
an analytic model of CMEs as an example of a fully three-dimensional
magnetic field structure in MHD force balance with an emerging CME. We
present the CME magnetic field and its associated density structure,
seen projected at the limb from two viewing angles perpendicular
to the plane of the sky, and emerging from disk center representing
``earth-directed'' CME events. The range of CME structures thus produced
compares well to existing CME white-light coronagraph and full disk
EUV and X-ray observations. In particular, we find that both 3-part
``front-cavity-core'' and ``U-shaped'' white light CMEs, as well as the
twin dimmings (also referred to as transient coronal holes) observed in
X-ray and EUV, can successfully be reproduced by the CME model. All of
these structures are a direct consequence of a single three-dimensional
magnetic field topology, viewed from different directions.
Title: Dynamical phenomena associated with a coronal mass ejection
Authors: Gopalswamy, N.; Kaiser, M. L.; MacDowall, R. J.; Reiner,
M. J.; Thompson, B. J.; Cyr, O. C. St.
Bibcode: 1999AIPC..471..641G
Altcode: 1999sowi.conf..641G
The flare-CME-shock relationship has been controversial for more than
two decades. This issue was traditionally addressed using white light
coronagraphic data on CMEs, H-alpha or GOES data on flares and radio
spectrographic data on shocks (inferred from metric type II radio
bursts). A wealth of new information has become available after the
advent of Yohkoh, SOHO and WIND missions that can be used to address
the dynamical phenomena associated with CMEs. We present multiwavelength
observations of the 1998 April 27 CME associated with coronal dimming,
an X-class flare and type II radio bursts. We find that the coronal
dimming observed in X-rays and EUV is indeed a CME signature and that
the CME clearly precedes the accompanying flare.
Title: Relationship between Ulysses plasma observations and solar
observations during the Whole Sun Month campaign
Authors: Riley, Pete; Gosling, J. T.; McComas, D. J.; Pizzo, V. J.;
Luhmann, J. G.; Biesecker, D.; Forsyth, R. J.; Hoeksema, J. T.;
Lecinski, A.; Thompson, B. J.
Bibcode: 1999JGR...104.9871R
Altcode:
In this report, we summarize measurements made by the plasma experiment
on the Ulysses spacecraft during the period designated as ``Whole Sun
Month'' (WSM, August 10 to September 8, 1996). This interval coincided
with the return of solar wind variability at Ulysses. Ulysses was
located at ~28°N heliographic latitude, at a heliocentric distance of
4.25 AU, and on the opposite side of the Sun from Earth. In particular,
we explore the evolution of the solar wind between the Sun and
Ulysses for several rotations surrounding WSM. Specifically, we map
Ulysses measurements back toward the Sun by applying a two-dimensional
inverse MHD algorithm. This approach is compared with the commonly
used constant speed (or ballistic) approximation. We find that the MHD
mapping technique produces substantially better results when compared
with solar observations. Both the Ulysses MHD-mapped results and the
solar observations are consistent with a picture of a modestly tilted
streamer belt (<10°) that was deformed northward by an active
region at 240°-270° longitude.
Title: SOHO Observations of a Helical Coronal Mass Ejection
Authors: Raymond, J. C.; Ciaravella, A.; van Ballegooijen, A.;
Thompson, B.
Bibcode: 1999AAS...194.1701R
Altcode: 1999BAAS...31..853R
The EIT, LASCO and UVCS instruments aboard SOHO observed a CME on
Dec. 11/12 1997. The ejected prominence material rose relatively
slowly, averaging 150 km/s, but Doppler shifts as great at -300 km/s
were seen in the O VI lines. The observed gas spans the temperature
range from about 30,000 K to 300,000 K. The observations can
be modeled as left-handed helix which untwists at about 0.0009
radians/sec. Considerable heating as the plasma moves from the
solar surface to 1.7 solar radii is required to explain the observed
temperature range.
Title: Microwave enhancement and variability in the elephant's trunk
coronal hole: Comparison with SOHO observations
Authors: Gopalswamy, N.; Shibasaki, K.; Thompson, B. J.; Gurman, J.;
DeForest, C.
Bibcode: 1999JGR...104.9767G
Altcode:
We report on an investigation of the microwave enhancement and its
variability in the elephant's trunk coronal hole observed during the
Whole Sun Month campaign (August 10 to September 9, 1996). The microwave
images from the Nobeyama radioheliograph were compared with magnetograms
and EUV images obtained simultaneously by the Michelson Doppler imager
and the extreme ultraviolet imaging telescope (EIT) on board the SOHO
spacecraft. The combined data set allowed us to understand the detailed
structure of the microwave enhancement in the spatial and temporal
domains. We find that the radio enhancement is closely associated
with the enhanced unipolar magnetic regions underlying the coronal
hole. The radio enhancement consists of a smooth component originating
from network cell interiors and a compact component associated with
network magnetic elements. When a minority polarity is present near
a majority polarity element, within the coronal hole, the resulting
mixed polarity region is associated with a bright-point-like emission
in coronal EUV lines such as the Fe XII 195 Å. These coronal bright
points are also observed distinctly in the EIT 304 Å band, but not
in microwaves. On the other hand, the lower-temperature line emission
(304 Å) and the microwave enhancement are associated with the unipolar
magnetic flux elements in the network. We found strong time variability
of the radio enhancement over multiple timescales, consistent with the
initial results obtained by SOHO instruments. The microwave enhancement
is most probably due to temperature enhancement in the chromosphere
and may be related to the origin of solar wind.
Title: Multi-wavelength observations of the onset phase of a coronal
mass ejection
Authors: Innes, D. E.; Inhester, B.; Srivastava, N.; Brekke, P.;
Harrison, R. A.; Matthews, S. A.; Noëns, J. C.; Schmieder, B.;
Thompson, B. J.
Bibcode: 1999SoPh..186..337I
Altcode:
The structure and dynamics of the initial phases of a coronal mass
ejection (CME) seen in soft X-ray, extreme ultraviolet and optical
emission are described. The event occurred on the SW limb of the Sun in
active region AR 8026 on 9 April 1997. Just prior to the CME there was
a class C1.5 flare. Images taken with the Extreme Ultraviolet Imaging
Telescope (EIT) reveal the emergence of a candle-flame shaped extreme
ultraviolet (EUV) cavity at the time of the flare. Yohkoh images,
taken about 15 min later, show that this cavity is filled with hot
X-ray emitting gas. It is most likely that this is the site of the
flare. Almost simultaneous to the flare, an Hα surge or small filament
eruption occurs about 50 arc sec northwards along the limb from the EUV
cavity. At both the site of the core of the hot, EUV cavity and the
filament ejection are X-ray jets. These jets seem to be connected by
hot loops near their bases. Both jets disappear within a few minutes
of one another.
Title: In-ecliptic CIR-associated energetic particle events and polar
coronal hole structures: SOHO/COSTEP observations for the Whole Sun
Month Campaign
Authors: Posner, Arik; Bothmer, Volker; Thompson, Barbara J.; Kunow,
Horst; Heber, Bernd; Müller-Mellin, Reinhold; Lazarus, Alan J.;
Szabo, Adam; Mikić, Zoran; Linker, Jon A.
Bibcode: 1999JGR...104.9881P
Altcode:
The Solar and Heliospheric Observatory (SOHO), in halo orbit around
the L1 Lagrangian point of the Sun-Earth system, combines a unique
set of instruments for studies of the Sun and the heliosphere. SOHO's
Comprehensive Suprathermal and Energetic Particle Analyser measures
in situ particles in the energy range 44 keV/particle to above 53
MeV/nucleon. For the time period of the Whole Sun Month Campaign in
mid 1996 we have identified recurrent energetic particle intensity
increases in association with corotating interaction regions (CIRs)
in the energy range <10 MeV. Solar wind measurements of the Wind
spacecraft were used to estimate the corresponding magnetic source
location in Carrington longitude for comparison of energetic particles
with synoptic maps of the lower corona, derived from images of SOHO's
Extreme-ultraviolet Imaging Telescope. The comparison reveals a close
relationship of latitudinal extensions of polar coronal holes, situated
in regions up to 40° away from the ecliptic, with CIR-associated
in-ecliptic particle events.
Title: Soft X-ray Observation of a Flare-Associated Coronal Wave
Authors: Hudson, H. S.; Lemen, J. R.; Thompson, B.; Uchida, Y.
Bibcode: 1999AAS...194.2205H
Altcode: 1999BAAS...31..860H
Recent EUV observations from the EIT instrument of SOHO have shown
the common occurrence of flare-associated global coronal waves, allies
of Type II burst exciters and chromospheric Moreton waves. Until now,
however, no direct soft X-ray detections have been reported. We have
studied Yohkoh SXT observations to understand this apparent discrepancy
between EUV and soft X-ray observations,and have now found good X-ray
evidence for a large-scale coronal wave launched during an X-class
flare of May 6, 1998. During the impulsive phase of this flare, a rapid
( ~ 10(3) km s(-1) ) bright front appeared to the north of the flare
core; later a more normal loop-like ejection emerged to the west at a
lower projected speed. We identify the rapid front with enhanced X-ray
emission from a global coronal wave. Wave signatures also appear in
SOHO EIT images and in the meter-wave dynamic spectrum from Hiraiso,
and SOHO LASCO detected a coronal mass ejection. NASA supported this
work under contract NAS 8-37334.
Title: YOHKOH SXT and SOHO EIT Observations of ``Sigmoid-to-Arcade''
Evolution of Structures Associated with Halo CMEs
Authors: Sterling, A. C.; Hudson, H. S.; Thompson, B. J.; Zarro, D. M.
Bibcode: 1999AAS...19410107S
Altcode: 1999BAAS...31..999S
A subset of the solar-disk counterparts to halo coronal mass ejections
(CMEs) display an evolution in soft X-rays (SXR) characterized by a
preflare ``S''-shaped structure, dubbed a ``sigmoid,'' evolving into
a postflare cusp or arcade. We examine the morphological properties
of the evolution of sigmoids into cusps and arcades for four such
regions associated with SXR flares, using the Soft X-ray Telescope
(SXT) on Yohkoh and the 195 Angstroms Fe xii\ channel of the EUV Imaging
Telescope (EIT) on SOHO. There is, at most, only a weak counterpart to
the SXR sigmoid in the preflare EUV images, indicating that the preflare
sigmoid has a temperature >1.5 MK\@. During the time of the flare
itself, however, an EUV sigmoid brightens near the location of the
SXR preflare sigmoid. Initially the SXR sigmoid lies along a magnetic
neutral line. As the SXR flare progresses new field lines appear with
orientation normal to the neutral line and with footpoints rooted in
opposite polarity regions; these footpoints are different from those of
the preflare sigmoid. The cusp structures in SXRs develop from these
newly-ignited field lines. In EIT images the EUV sigmoid broadens out
as the flare progresses, forming an arcade which resides beneath the
SXR cusp. In many respects, our findings are consistent with a standard
picture where the origin of the flare and CME is due to the eruption
of a filament-like feature, and the stretching of overlying preflare
fields produces the cusp. We do not, however, observe these preflare
overlying fields prior to flare onset. This work was supported by the
NRL Naval basic research program and NASA.
Title: Magnetohydrodynamic modeling of the solar corona during Whole
Sun Month
Authors: Linker, J. A.; Mikić, Z.; Biesecker, D. A.; Forsyth, R. J.;
Gibson, S. E.; Lazarus, A. J.; Lecinski, A.; Riley, P.; Szabo, A.;
Thompson, B. J.
Bibcode: 1999JGR...104.9809L
Altcode:
The Whole Sun Month campaign (August 10 to September 8, 1996) brought
together a wide range of space-based and ground-based observations
of the Sun and the interplanetary medium during solar minimum. The
wealth of data collected provides a unique opportunity for testing
coronal models. We develop a three-dimensional magnetohydrodynamic
(MHD) model of the solar corona (from 1 to 30 solar radii) applicable
to the WSM time period, using measurements of the photospheric
magnetic field as boundary conditions for the calculation. We compare
results from the computation with daily and synoptic white-light and
emission images obtained from ground-based observations and the SOHO
spacecraft and with solar wind measurements from the Ulysses and WIND
spacecraft. The results from the MHD computation show good overall
agreement with coronal and interplanetary structures, including the
position and shape of the streamer belt, coronal hole boundaries,
and the heliospheric current sheet. From the model, we can infer the
source locations of solar wind properties measured in interplanetary
space. We find that the slow solar wind typically maps back to near
the coronal hole boundary, while the fast solar wind maps to regions
deeper within the coronal holes. Quantitative disagreements between
the MHD model and observations for individual features observed during
Whole Sun Month give insights into possible improvements to the model.
Title: Interplanetary scintillation measurements of the solar
wind during Whole Sun Month: Comparisons with coronal and in situ
observations
Authors: Breen, A. R.; Mikic, Z.; Linker, J. A.; Lazarus, A. J.;
Thompson, B. J.; Biesecker, D. A.; Moran, P. J.; Varley, C. A.;
Williams, P. J. S.; Lecinski, A.
Bibcode: 1999JGR...104.9847B
Altcode:
Two-site observations of interplanetary scintillation using the
EISCAT facility can provide measurements of solar wind velocity at
any point in the heliosphere between 15 and 120 solar radii (R). In
this paper we discuss a series of observations made as part of the
Whole Sun Month campaign (August 10 to September 8 1996) and compare
the results with coronal data and in-situ measurements made during
the campaign. The results of the comparison revealed extremely good
agreement between solar wind speeds measured by IPS at 16-73 R and in
situ measurements at 213 R and beyond, both in the general morphology of
the solar wind and in the absolute velocities observed. These results
confirm that structures in the solar wind, originating in the corona,
preserve their form out to 910 R or more. Observations of fast solar
wind were always associated with coronal holes and slow wind with the
bright corona. Velocities intermediate between normal fast and slow
flow speeds are associated with interaction regions between fast and
slow flow and are also found above the boundaries of coronal holes.
Title: Synoptic Sun during the first Whole Sun Month Campaign:
August 10 to September 8, 1996
Authors: Biesecker, D. A.; Thompson, B. J.; Gibson, S. E.; Alexander,
D.; Fludra, A.; Gopalswamy, N.; Hoeksema, J. T.; Lecinski, A.;
Strachan, L.
Bibcode: 1999JGR...104.9679B
Altcode:
A large number of synoptic maps from a variety of instruments are used
to show the general morphology of the Sun at the time of the First
Whole Sun Month Campaign. The campaign was conducted from August 10 to
September 8, 1996. The synoptic maps cover the period from Carrington
rotation 1912/253° to Carrington rotation 1913/45°. The synoptic maps
encompass both on-disk data and limb data from several heights in the
solar atmosphere. The maps are used to illustrate which wavelengths and
data sets show particular features, such as active regions and coronal
holes. Of particular interest is the equatorial coronal hole known as
the ``elephant's trunk,'' which is clearly evident in the synoptic
maps of on-disk data. The elephant's trunk is similar in appearance
to the Skylab-era, ``Boot of Italy,'' equatorial coronal hole. The
general appearance of the limb maps is explained as well. The limb
maps also show evidence for equatorial coronal holes.
Title: The Characteristics and Geoeffectiveness of SOHO-LASCO
Halo CMEs
Authors: Webb, D. F.; St. Cyr, O. C.; Plunkett, S. P.; Howard, R. A.;
Thompson, B. J.
Bibcode: 1999AAS...194.1703W
Altcode: 1999BAAS...31..853W
Halo-type CMEs had been rarely reported in solar coronagraph
observations before the SOHO mission. Because of their increased
sensitivity and dynamic range, the SOHO LASCO coronagraphs are now
observing many halo or partial-halo CMEs. A halo CME, especially
when associated with solar activity near sun center, is important
for Space Weather concerns because it suggests the launch of
a geoeffective disturbance toward Earth. We present statistical
summaries of the LASCO halo CMEs observed during the first 2.5 years
of SOHO observations. These include their occurrence rates, speeds
and morphology, and comparison of the halo CME population with the
general characteristics of all LASCO CMEs during this period. As a
test of the geoeffectiveness of halo CMEs, we also examined a 6-month
period just after solar minimum from December 1996 through May 1997
during which halo CMEs and geomagnetic storms occurred at a similar
rate of 2-3/month. All 7 of the halo CMEs confidently associated with
frontside activity were followed 3-5 days later by interplanetary
shocks, magnetic clouds and moderate storms at Earth. In the opposite
sense most of the moderate storms during this period were associated
with halo CMEs. We will present the results of this study. This work
was supported by AFOSR grant AF49620-97-1-0070.
Title: Injection of>~10 MeV Protons in Association with a Coronal
Moreton Wave
Authors: Torsti, Jarmo; Kocharov, Leon G.; Teittinen, Matti; Thompson,
Barbara J.
Bibcode: 1999ApJ...510..460T
Altcode:
We report extreme-UV observations of the coronal Moreton wave and
concurrent observations of ~10-100 MeV protons. Observations are
carried out with the Extreme-UV Imaging Telescope and the Energetic
and Relativistic Nuclei and Electron instrument on board the SOHO
spacecraft. We study the proton events associated with coronal mass
ejections (CMEs) centered near the central meridian. Observations reveal
the initial injection of >~10 MeV protons during the period when the
coronal Moreton wave was traversing the western hemisphere of the Sun,
this being an early signature of the CME launch. Acceleration of the
CME-associated protons starts during the CME liftoff, while the main
proton production occurs several hours later, when the CME expands
in the interplanetary medium. Between the first proton production
and the maximum intensity time, a spectral softening is observed. We
analyze in detail the 1997 September 24 event. Development of the
event indicates that the spectral softening may be due to a change
in the acceleration regime, so the proton production starts with the
less intensive but hard-spectrum injection and then moves to the more
intensive but soft-spectrum injection farther from the Sun.
Title: Ultraviolet and Optical Observations of a Coronal Transient
with SOHO
Authors: Ciaravella, A.; Raymond, J. C.; Strachan, L.; Thompson,
B. J.; Cyr, O. C. St.; Gardner, L.; Modigliani, A.; Antonucci, E.;
Kohl, J.; Noci, G.
Bibcode: 1999ApJ...510.1053C
Altcode:
A coronal transient was observed on 1997 March 6 at 1.6
Rsolar over an active region on the east limb. We observed
both the edge of horizontally compressed gas and the diffuse curtain of
coronal material. The region was monitored for 4 hr, and the H I Lyα,
O VI λλ1031.91, 1037.61, N V λλ1242.80, 1238.80, and O V] λ1218.35
lines were detected during the ejection evolution. The density,
velocity, temperature, and oxygen abundance of the ejected plasma have
been obtained from the observed spectra. Intermediate temperature lines
of N V, O VI, and O V show a large enhancement, suggesting a quite
narrow range of plasma temperature around 4×105 K. Doppler
shifts of the ejected material evolve from an initial blueshift of 100
km s-1 to a redshift of 145 km s-1. The outflow
velocity, as determined by Doppler dimming analysis of the O VI doublet,
is only about 20 km s-1.
Title: Tales of an Elephant's Trunk
Authors: Bromage, B. J. I.; Clegg, J. R.; Del Zanna, G.; Thompson, B.
Bibcode: 1999ASPC..158..370B
Altcode: 1999ssa..conf..370B
No abstract at ADS
Title: Nonthermal Radio Signatures of Coronal Disturbances with and
without Coronal Mass Ejections
Authors: Aurass, H.; Vourlidas, A.; Andrews, M. D.; Thompson, B. J.;
Howard, R. H.; Mann, G.
Bibcode: 1999ApJ...511..451A
Altcode:
This study presents data on two events from the Extreme-UV Imaging
Telescope (EIT) and the Large Angle and Spectroscopic Coronagraph
instruments (C1, C2, and C3), Geostationary Operational Environmental
Satellite (GOES) soft X-ray data, and 40-800 MHz radio spectra of the
Astrophysical Institute Potsdam. At first glance, the two events appear
similar. However, one event decays after a flare-related ejection of
cold and hot matter into the lower corona causing only brightness
changes in EIT and C1, while the other event marks the onset of a
coronal mass ejection (CME) that propagates with a leading-edge speed
of ~530 km s-1 between 2 and 30 Rsolar. The
radio data reveal two differences between the CME and non-CME events:
(1) a characteristic faint type III burst group in the time interval
with the first clearly CME-related structural change in the coronagraph
images and (2) a continuum emission with a frequency drift during the
passage of the CME matter through the C1 field of view. Furthermore,
we show that the radio spectral data can provide essential information
on the timing of the early stages of CME formation and the initial
mass motions associated with the ejection.
Title: Observations of Coronal Structures Above an Active Region by
EIT and Implications for Coronal Energy Deposition
Authors: Neupert, W. M.; Newmark, J.; Delaboudinière, J. -P.;
Thompson, B. J.; Catura, R. C.; Moses, J. D.; Gurman, J. B.;
Portier-Fozzani, F.; Gabriel, A. H.; Artzner, G.; Clette, F.; Cugnon,
P.; Maucherat, A. J.; Defise, J. M.; Jamar, C.; Rochus, P.; Dere,
K. P.; Howard, R. A.; Michels, D. J.; Freeland, S.; Lemen, J. R.;
Stern, R. A.
Bibcode: 1998SoPh..183..305N
Altcode:
Solar EUV images recorded by the EUV Imaging Telescope (EIT) on SOHO
have been used to evaluate temperature and density as a function of
position in two largescale features in the corona observed in the
temperature range of 1.0-2.0 MK. Such observations permit estimates
of longitudinal temperature gradients (if present) in the corona and,
consequently, estimates of thermal conduction and radiative losses
as a function of position in the features. We examine two relatively
cool features as recorded in EIT's Fe ix/x (171 Å) and Fe xii (195 Å)
bands in a decaying active region. The first is a long-lived loop-like
feature with one leg, ending in the active region, much more prominent
than one or more distant footpoints assumed to be rooted in regions of
weakly enhanced field. The other is a near-radial feature, observed
at the West limb, which may be either the base of a very high loop
or the base of a helmet streamer. We evaluate energy requirements to
support a steady-state energy balance in these features and find in
both instances that downward thermal conductive losses (at heights
above the transition region) are inadequate to support local radiative
losses, which are the predominant loss mechanism. The requirement that a
coronal energy deposition rate proportional to the square of the ambient
electron density (or pressure) is present in these cool coronal features
provides an additional constraint on coronal heating mechanisms.
Title: Erupting Solar Magnetic Flux Ropes - Theory and Observation
Authors: Krall, J.; Chen, J.; Santoro, R. A.; Duffin, R. T.; Howard,
R. A.; Thompson, B. J.
Bibcode: 1998APS..DPP.F3S20K
Altcode:
The dynamics of magnetic flux ropes near the sun and in interplanetary
space are studied using a modified version of the flux rope model of
Chen and Garren. (Chen and Garren, GRL, 20, 2319, 1993) In this model, a
coronal mass ejection (CME) corresponds to a flux rope with foot points
that remain anchored in the photosphere. The model flux rope eruption
can be driven by a rapid increase in poloidal flux (flux injection), a
gradual increase in poloidal flux (photospheric foot-point twisting), or
a rapid increase in the volume of hot plasma within the flux rope (mass
injection). Model results are compared with data from the LASCO and EIT
instruments on the Solar and Heliospheric Observatory spacecraft and
with interplanetary magnetic cloud data over the range 0.5 to 4.0 AU.
Title: First VLA Observations of Nonthermal Metric Bursts Associated
with Coronal Mass Ejections Detected by the Solar and Heliospheric
Observatory
Authors: Willson, R. F.; Redfield, S. L.; Lang, K. R.; Thompson,
B. J.; St. Cyr, O. C.
Bibcode: 1998ApJ...504L.117W
Altcode:
We present the first observations of nonthermal decimetric burst
emission of the Sun using the new 400 cm (74 MHz) system at the VLA. Our
VLA observations were carried out in collaboration with the Large
Angle Spectroscopic Coronagraph (LASCO) and the Extreme-Ultraviolet
Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory
spacecraft. Full-disk observations at 400 and 91 cm were used to
study the spatial and temporal variations of nonthermal radio bursts
during coronal mass ejections (CMEs) detected by LASCO as well as
transient extreme-ultraviolet brightenings detected by the EIT. VLA
snapshot maps at 400 cm revealed impulsive burst emission in the low
corona that began near the estimated start time of the CME activity;
that beginning also coincided with a C1.1 GOES X-ray burst and an EIT
flarelike brightening. The nonthermal metric bursts then continued
sporadically during the next several hours, which included the ejection
of spatially separated CME components. The 400 cm bursts are contained
within curved, or archlike, sources at a fixed radial distance but with
a varying position between two active regions detected by the EIT near
the limb, suggesting that they were emitted within large-scale magnetic
loops. Our 91 cm observations also show the onset of a long-lasting type
I noise storm following the initiation of CME activity, again suggesting
an intimate relationship between the production of nonthermal particles
and large-scale evolving plasma-magnetic field structures in the corona.
Title: Geomagnetic storms caused by coronal mass ejections (CMEs):
March 1996 through June 1997
Authors: Brueckner, G. E.; Delaboudiniere, J. -P.; Howard, R. A.;
Paswaters, S. E.; St. Cyr, O. C.; Schwenn, R.; Lamy, P.; Simnett,
G. M.; Thompson, B.; Wang, D.
Bibcode: 1998GeoRL..25.3019B
Altcode:
(1) All but two geomagnetic storms with Kp ≥ 6 during the operating
period (March 1996 through June 1997) of the Large Angle Spectroscopic
Coronagraph (LASCO) experiment on the Solar and Heliospheric Observatory
(SOHO) spacecraft can be traced to Coronal Mass Ejections (CMEs). (2)
These geomagnetic storms are not related to high speed solar wind
streams. (3) The CMEs which cause geomagnetic effects, can be classified
into two categories: Halo events and toroidal CMEs. (4) The CMEs are
accompanied by Coronal Shock Waves as seen in the Extreme Ultraviolet
Imaging Telescope (EIT) Fe XII images. (5) Some CMEs are related to
flares, others are not. (6) In many cases, the travel time between
the explosion on the Sun and the maximum geomagnetic activity is about
80 hours.
Title: The Solar Minimum Active Region 7978, Its X2.6/1B Flare, CME,
and Interplanetary Shock Propagation of 9 July 1996
Authors: Dryer, M.; Andrews, M. D.; Aurass, H.; DeForest, C.; Galvin,
A. B.; Garcia, H.; Ipavich, F. M.; Karlický, M.; Kiplinger, A.;
Klassen, A.; Meisner, R.; Paswaters, S. E.; Smith, Z.; Tappin,
S. J.; Thompson, B. J.; Watari, S. I.; Michels, D. J.; Brueckner,
G. E.; Howard, R. A.; Koomen, M. J.; Lamy, P.; Mann, G.; Arzner, K.;
Schwenn, R.
Bibcode: 1998SoPh..181..159D
Altcode:
The first X-class flare in four years occurred on 9 July 1996. This
X2.6/1B flare reached its maximum at 09:11 UT and was located in active
region 7978 (S10° W30°) which was an old-cycle sunspot polarity
group. We report the SOHO LASCO/EIT/MDI and SOONSPOT observations before
and after this event together with Yohkoh SXT images of the flare,
radio observations of the type II shock, and GOES disk-integrated soft
X-ray flux during an extended period that included energy build-up in
this active region.
Title: On the relationship between coronal mass ejections and
magnetic clouds
Authors: Gopalswamy, N.; Hanaoka, Y.; Kosugi, T.; Lepping, R. P.;
Steinberg, J. T.; Plunkett, S.; Howard, R. A.; Thompson, B. J.;
Gurman, J.; Ho, G.; Nitta, N.; Hudson, H. S.
Bibcode: 1998GeoRL..25.2485G
Altcode:
We compare the substructures of the 1997 February 07 coronal mass
ejection (CME) observed near the Sun with a corresponding event in
the interplanetary medium to determine the origin of magnetic clouds
(MCs). We find that the eruptive prominence core of the CME observed
near the Sun may not directly become a magnetic cloud as suggested by
some authors and that it might instead become the ”pressure pulse”
following the magnetic cloud. We substantiate our conclusions using time
of arrival, size and composition estimates of the CME-MC substructures
obtained from ground based, SOHO and WIND observations.
Title: Type II radio emissions in the frequency range from 1-14 MHz
associated with the April 7, 1997 solar event
Authors: Kaiser, M. L.; Reiner, M. J.; Gopalswamy, N.; Howard, R. A.;
St. Cyr, O. C.; Thompson, B. J.; Bougeret, J. -L.
Bibcode: 1998GeoRL..25.2501K
Altcode:
We present an analysis of radio emissions associated with the April
7, 1997 solar eruptive event. The event consisted of a filament
disappearance, a complex two-phase coronal mass ejection (CME),
and a C6.9, 2N flare. At the same time, intermittent type II radio
emissions in the frequency range 1-10 MHz, corresponding to an altitude
range of 2-15 Ro, were observed by the Wind/WAVES radio
receiver. Using the onset times and inferred heights and speeds
of the radio bursts, we considered both a CME-driven shock and a
flare-associated blast wave shock as possible causes of the type II
radio emissions. We conclude that some of the radio emissions in the
WAVES data are associated with each shock. The type II radio emissions
associated with the blast wave shock were farther from the sun than
any emission of this type that has been reported previously.
Title: Cradle to grave tracking of the January 6-11,1997 Sun-Earth
connection event
Authors: Fox, N. J.; Peredo, M.; Thompson, B. J.
Bibcode: 1998GeoRL..25.2461F
Altcode:
During the interval January 6-11, 1997, the satellites and ground
facilities of the International Solar-Terrestrial Physics (ISTP)
“Observatory” tracked a solar eruption from the Sun to the
Earth. The resulting Coronal Mass Ejection (CME) took four days to
travel through interplanetary space before arriving at Earth, where it
caused electromagnetic disturbances and spectacular aurorae. The initial
expulsion lifted off the Sun on January 6, the resulting magnetic
cloud arrived on January 10, and its effects lasted over 24 hours. The
initial solar observations from SOHO were reported on January 7, during
an ISTP Science Workshop on Sun-Earth Connection events. This alerted
the community to the impending arrival of the CME thereby allowing the
event to be monitored in ‘realtime’ using the wide variety of ISTP
instruments. This event provided the first ever end to end tracking of
a space storm. Further, it provided a strong pressure pulse of extremely
high density resulting in the compression of the magnetopause to within
geosynchronous orbit during northward IMF conditions. Here we present
an overview of the event and available observations.
Title: Evidence for multiple ejecta: April 7-11, 1997, ISTP Sun-Earth
connection event
Authors: Berdichevsky, D.; Bougeret, J. -L.; Delaboudinière, J. -P.;
Fox, N.; Kaiser, M.; Lepping, R.; Michels, D.; Plunkett, S.; Reames,
D.; Reiner, M.; Richardson, I.; Rostoker, G.; Steinberg, J.; Thompson,
B.; von Rosenvinge, T.
Bibcode: 1998GeoRL..25.2473B
Altcode:
Evidence is presented that the enhanced geomagnetic activity, on
April 10-11, 1997, was caused by one of two ejecta that left the
Sun at ≈ 14 UT on April 7. This ejecta was not directly detected
at the Earth. The evidence for this interpretation is based on WIND
spacecraft observations in the solar wind (SW). It is consistent with:
(i) measured velocities of the coronal mass ejections from the SOHO
coronagraph; (ii) the initial propagation speed of the shock generated
in this event, estimation from type II radio burst observations from the
WAVES instrument on WIND, and (iii) the time profile of energetic ions
observed by EPACT on WIND. This locally unobserved ejecta (moving at 600
to 700 kms-1) generated a fast shock which accelerated ions
to several tens of MeV/amu. The inferred passage of the first ejecta
close to Earth (on April 10 to 11) is based on the observation of an
interplanetary shock (IS) ahead of a field and plasma compressional
region where the draping of the SW flow and possibly the changes in
the direction of the IMF are consistent with a location northward of a
faster ejecta. This ejecta was responsible for disturbed SW conditions
including approximately ten hours of southward orientation of the
interplanetary magnetic field (IMF) and a ram pressure many times
above normal. The slower moving ejecta was directed toward Earth and
was observed with WIND from about 0550 until 1500 UT on April 11. It
had a strong northward IMF and produced density enhancements which
elevated the ram pressure to more than four times above normal.
Title: LASCO observations of an Earth-directed coronal mass ejection
on May 12, 1997
Authors: Plunkett, S. P.; Thompson, B. J.; Howard, R. A.; Michels,
D. J.; St. Cyr, O. C.; Tappin, S. J.; Schwenn, R.; Lamy, P. L.
Bibcode: 1998GeoRL..25.2477P
Altcode:
Coronal mass ejections (CMEs) that occur near the center of the
solar disk are most likely to impact Earth. Detection of such
events as ‘halos’ in white-light coronagraphs has been somewhat
controversial in recent years. We present observations from the LASCO
coronagraphs on SOHO that provide convincing evidence of the detection
of an Earth-directed CME on May 12, 1997. The event began at about
04:35 UT and propagated outwards from the Sun with a projected speed
of around 250 km s-1. Using some reasonable assumptions
about the geometry of the CME, we estimate the true speed to be around
600 km s-1. The onset of the event in LASCO is coincident
(to within measurement uncertainties) with an eruptive event detected
in extreme ultraviolet observations of the solar disk by the SOHO
EIT. This is the first reported observation of a halo CME at projected
distances greater than 10 R⊙, with a clearly identifiable
solar origin. We discuss the possibility that at least some of the
enhanced brightness observed by LASCO may be due to a compressional
wave propagating in the corona.
Title: SOHO/EIT observations of an Earth-directed coronal mass
ejection on May 12, 1997
Authors: Thompson, B. J.; Plunkett, S. P.; Gurman, J. B.; Newmark,
J. S.; St. Cyr, O. C.; Michels, D. J.
Bibcode: 1998GeoRL..25.2465T
Altcode:
An earth-directed coronal mass ejection (CME) was observed on May 12,
1997 by the SOHO Extreme ultraviolet Imaging Telescope (EIT). The CME,
originating north of the central solar meridian, was later observed by
the Large Angle Spectrometric Coronagraph (LASCO) as a “halo” CME:
a bright expanding ring centered about the occulting disk. Beginning at
about 04:35 UT, EIT recorded several CME signatures, including dimming
regions close to the eruption, post-eruption arcade formation, and a
bright wavefront propagating quasi-radially from the source region. Each
of these phenomena appear to be associated with the same eruption, and
the onset time of these features corresponds with the estimated onset
time observed in LASCO. We discuss the correspondence of these features
as observed by EIT with the structure of the CME in the LASCO data.
Title: Empirical Models of Temperature, Densities, and Velocities
in the Solar Corona
Authors: Fludra, A.; Strachan, L.; Alexander, D.; Bagenal, F.;
Biesecker, D. A.; Dobrzycka, D.; Galvin, A. B.; Gibson, S.; Hassler,
D.; Yo, Y. -K.; Panasyuk, A. V.; Thompson, B.; Warren, H.; del Zanna,
G.; Zidowitz, S.; Antonucci, E.; Bromage, B. J. I.; Giordano, S.
Bibcode: 1998EOSTr..79..278F
Altcode:
We present empirical results for temperatures, densities, and outflow
velocities of constituents of the solar corona from 1 to 3 Ro in
polar coronal holes and an equatorial streamer. Data were obtained
from a variety of space and ground-based instruments during August
1996 as part of the SOHO Whole Sun Month Campaign. From white light
data obtained with the SOHO/LASCO/C2 and HAO/Mauna Loa coronagraphs,
we determine electron densities and compare them to those determined
from the density-sensitive EUV line ratio of Si IX 350/342 Angstroms
observed by the SOHO/Coronal Diagnostic Spectrometer (CDS). Moreover,
from the white light density profiles we calculate temperature profiles
and compare to temperature diagnostic information from EUV lines and
soft X-ray images from Yohkoh. H I Ly alpha and O VI 1032/1037 Angstrom
intensities from the SOHO Ultraviolet Coronagraph Spectrometer (UVCS)
are used to estimate both the direction and magnitude of plasma outflow
velocities in coronal holes and streamers above 1.5 Ro. The velocities
are derived using densities from white light coronagraph data and
coronal electron temperature estimates derived from Ulysses/SWICS
ion composition data. Near the base of the corona we find the white
light and spectral analysis produce consistent density and temperature
information. In the extended corona we find results consistent with
high outflow velocities and a superradial outflow geometry in polar
coronal holes.
Title: Coordinated Observations with SOHO, YOHKOH and VLA
Authors: Aschwanden, Markus J.; Bastian, Tim S.; Nitta, Nariaki;
Newmark, Jeff; Thompson, Barbara J.; Harrison, Richard A.
Bibcode: 1998ASPC..155..311A
Altcode: 1998sasp.conf..311A
No abstract at ADS
Title: Comparison of Microwave and SOHO Synoptic Maps of the Sun
During the Whole Sun Month, 1996
Authors: Gopalswamy, N.; Thompson, B. J.; Shibasaki, K.
Bibcode: 1998ASPC..140..401G
Altcode: 1998ssp..conf..401G
No abstract at ADS
Title: 3-Dimensional Models of Active Region Loops
Authors: Aschwanden, M. J.; Neupert, W. M.; Newmark, J.; Thompson,
B. J.; Brosius, J. W.; Holman, G. D.; Harrison, R. A.; Bastian, T. S.;
Nitta, N.; Hudson, H. S.; Zucker, A.
Bibcode: 1998ASPC..155..145A
Altcode: 1998sasp.conf..145A
No abstract at ADS
Title: Filament Disparition Brusque and CME - September 25-26,
1996 Event
Authors: van Driel-Gesztelyi, L.; Schmieder, B.; Aulanier, G.;
Demoulin, P.; Martens, P. C. H.; Zarro, D.; Deforest, C.; Thompson,
B.; St. Cyr, C.; Kucera, T.; Burkepile, J. T.; White, O. R.; Hanaoka,
Y.; Nitta, N.
Bibcode: 1998ASPC..150..366V
Altcode: 1998IAUCo.167..366V; 1998npsp.conf..366V
No abstract at ADS
Title: LASCO/EIT Observations of Coronal Mass Ejections from
Large-Scale Filament Channels
Authors: Plunkett, S. P.; Dere, K. P.; Howard, R. A.; Michels, D. J.;
Brueckner, G. E.; Thompson, B. J.; Delaboudiniere, J. -P.
Bibcode: 1998ASPC..150..475P
Altcode: 1998npsp.conf..475P; 1998IAUCo.167..475P
No abstract at ADS
Title: Nonthermal Radio Signatures of Coronal Disturbances with and
without Mass Ejections
Authors: Aurass, H.; Vourlidas, A.; Andrews, M. D.; Thompson, B. J.;
Howard, R. H.; Mann, G.
Bibcode: 1998cee..workE..20A
Altcode:
We show that the radio signature of nonthermal electrons can be a
sensitive indicator of small scale energy release related to topological
changes in coronal magneto-plasma structures. We compare two events
using images from the Extreme-UV Imaging Telescope (EIT) and the Large
Angle and Spectroscopic Coronagraph (LASCO) instruments, GOES soft
X-ray data, and 40--800 MHz radio spectra of the AI Potsdam. At first
glance, both events appear similar. One event decays after a prominence
eruption causing only brightness changes in the EIT and C1 images. But
the other event marks the onset of a large coronal mass ejection (CME)
that propagates with a speed of ~530kms^{-1} between 2--30 R_odot. The
CME formation is accompanied by an unspectacular faint group of metric
drift bursts starting in the spectral range 170--200 MHz (at a height
1.20-1.25 R_odot) and lasts for ~3 min. During the CME lift-off,
the frequency drift of an associated type IV continuum translates to
a speed of ~90kms^{-1}. The same speed is obtained from the height
change of leading CME features in LASCO-C1. The non-CME event is
accompanied by a non-drifting continuum and lacks any type III burst
activity. We offer a number of explanations for the CME absence. Also,
in the non-CME case we show that the post-prominence eruption current
sheet can be detected in the EIT and C1 images. Its lower part appears
as a bright blob in EIT on the top of a loop arcade. The brightness
of this blob corresponds to a soft X-ray long duration event (LDE)
decay. Our study suggests that prominence eruptions and soft X-ray
LDEs are insufficient to reveal a CME.
Title: New Images of the Solar Corona
Authors: Gurman, Joseph B.; Thompson, Barbara J.; Newmark, Jeffrey A.;
Deforest, Craig E.
Bibcode: 1998ASPC..154..329G
Altcode: 1998csss...10..329G
In 1.5 years of operation, The Extreme Ultraviolet Imaging Telescope
(EIT) on SOHO has obtained over 40,000 images of the Sun in four
wavebands between 171 Angstroms and 304 Angstroms, with spatial
resolution limited only by the pixel scale of 2.59 arcsec. These
images, and in particular compilations of time series of images into
digital movies, have changed several of our ideas about the corona
at temperatures of 0.9 - 2.5 MK. For the first time, we are able to
see outflow in polar plumes and microjets inputting momentum into the
high-speed, polar wind flow. For the first time, in conjunction with the
LASCO coronagraphs and ground-based He I imagers, we have been able to
see all the structures involved in coronal mass ejections (CMEs), from
the surface of the Sun to 30 solar radii above it. In several cases, we
have been able to observe directly the dramatic Moreton waves emanating
from the active region where the CMEs originate, and radiating across
virtually the entire visible hemisphere of the Sun. We interpret these
large-scale coronal disturbances as fast-mode waves. Such events appear
in the SOHO-LASCO coronagraphs as earthward-directed, and several have
been detected by solar wind monitoring experiments on SOHO and other
spacecraft. We have been able to view a variety of small-scale phenomena
as well, including motions in prominences and filaments, macrospicular
and polar microjet eruptions, and fine structures in the polar crown
filament belt. The multi-wavelength capability of EIT makes it possible
to determine the temperature of the coronal plasma and, here, too,
we have been afforded a novel view: the heating in coronal active
regions occurs over a considerably larger area than the high-density
loops structures alone (i.e., bright features) would indicate.
Title: Analysis of Active Regions via 3D Rendering Techniques
Authors: Alexander, D.; Gary, G. Allen; Thompson, B. J.
Bibcode: 1998ASPC..155..100A
Altcode: 1998sasp.conf..100A
No abstract at ADS
Title: VLA-SOHO Observations of Evolving Coronal Structures on the Sun
Authors: Willson, R. F.; Lang, K. R.; Thompson, B.; Schuehle, U.;
Zarro, D. M.
Bibcode: 1998ASPC..154..727W
Altcode: 1998csss...10..727W
Very Large Array (VLA) observations at 3.5, 6.2, and 91.6 cm wavelength
have been combined with EUV spectroheliograms from the Solar and
Heliospheric Observatory (SOHO) Coronal Diagnostic Spectrometer (CDS)
and Extreme Ultraviolet Telescope (EIT) to study evolving sources in the
transition region and corona above a solar active region. In some cases,
transient events, lasting minutes to tens of minutes, were observed
at both radio and EUV wavelengths, while other events were detected
in only one spectral domain. The combined data sets suggest that the
EUV-associated microwave sources are produced by thermal gyroresonance
or nonthermal gyrosynchrotron radiation, primarily in regions of high
magnetic field strength near sunspots. Observations at 91.6 cm also
show the sudden appearance of a low-lying, nonthermal source in the
low corona around the time that cool, outwardly-propagating plasma
was detected by the SOHO/EIT.
Title: Development of Coronal Mass Ejections and Association with
Interplanetary Events
Authors: Pick, M.; Maia, D.; Howard, R.; Thompson, B.; Lanzerotti,
L. J. L.; Bothmer, V.; Lamy, P.
Bibcode: 1997ESASP.415..195P
Altcode: 1997cpsh.conf..195P
No abstract at ADS
Title: Overview of the ISTP Sun-Earth Connection Event of January
6-11 1997
Authors: Peredo, M.; Fox, Nicola; Thompson, Barbara
Bibcode: 1997ESASP.415..517P
Altcode: 1997cpsh.conf..517P
No abstract at ADS
Title: Solar Energetic Particle Events and Coronal Mass Ejections:
New Insights from SOHO
Authors: Bothmer, V.; Posner, A.; Kunow, H.; Müller-Mellin, R.;
Herber, B.; Pick, M.; Thompson, B. J.; Delaboudinière, J. -P.;
Brueckner, G. E.; Howard, R. A.; Michels, D. J.; Cyr, C. St.; Szabo,
A.; Hudson, H. S.; Mann, G.; Classen, H. -T.; McKenna-Lawlor, S.
Bibcode: 1997ESASP.415..207B
Altcode: 1997cpsh.conf..207B
No abstract at ADS
Title: White-Light Coronal Mass Ejections: A New Perspective from
LASCO
Authors: St. Cyr, O. C.; Howard, R. A.; Simnett, G. M.; Gurman, J. B.;
Plunkett, S. P.; Sheeley, N. R.; Schwenn, R.; Koomen, M. J.; Brueckner,
G. E.; Michels, D. J.; Andrews, M.; Biesecker, D. A.; Cook, J.; Dere,
K. P.; Duffin, R.; Einfalt, E.; Korendyke, C. M.; Lamy, P. L.; Lewis,
D.; Llebaria, A.; Lyons, M.; Moses, J. D.; Moulton, N. E.; Newmark,
J.; Paswaters, S. E.; Podlipnik, B.; Rich, N.; Schenk, K. M.; Socker,
D. G.; Stezelberger, S. T.; Tappin, S. J.; Thompson, B.; Wang, D.
Bibcode: 1997ESASP.415..103S
Altcode: 1997cpsh.conf..103S
No abstract at ADS
Title: Magnetic Flux in Modeled Magnetic Clouds at 1 AU and Some
Specific Comparisons to Associated Photospheric Flux
Authors: Lepping, R. P.; Szabo, A.; DeForest, C. E.; Thompson, B. J.
Bibcode: 1997ESASP.415..163L
Altcode: 1997cpsh.conf..163L
No abstract at ADS
Title: Fitting a 3-D Analytic Model of the Coronal Mass Ejection
to Observations
Authors: Gibson, S. E.; Biesecker, D.; Fisher, R.; Howard, R. A.;
Thompson, B. J.
Bibcode: 1997ESASP.415..111G
Altcode: 1997cpsh.conf..111G
No abstract at ADS
Title: The Structure and Evolution of Solar Coronal Holes Observed
by SOHO During August and September 1996
Authors: Bromage, B. J. I.; del Zanna, G.; Fludra, A.; DeForest, C.;
Thompson, B.
Bibcode: 1997ESASP.415..307B
Altcode: 1997cpsh.conf..307B
No abstract at ADS
Title: Fluxes of MeV Particles at Earth's Orbit and their Relationship
with the Global Structure of the Solar Corona: Observations from SOHO
Authors: Posner, A.; Bothmer, V.; Kunow, H.; Herber, B.;
Müller-Mellin, R.; Delaboudinière, J. -P.; Thompson, B. J.;
Brückner, G. E.; Howard, R. A.; Muchels, D. J.
Bibcode: 1997ESASP.415..377P
Altcode: 1997cpsh.conf..377P
No abstract at ADS
Title: Solar Active Region Movies seen by the SOHO Extreme-ultraviolet
Telescope
Authors: Newmark, J. S.; Thompson, B.; Gurman, J. B.; Delaboudiniere,
J. P.; Aschwanden, Markus; Mason, Helen
Bibcode: 1997AAS...191.7307N
Altcode: 1997BAAS...29.1321N
The Extreme-ultraviolet Imaging Telescope (EIT) on board the SOHO (SOlar
and Heliospheric Observatory) satellite provides wide-field images of
the corona and transition region on the solar disc and up to 1.4 solar
radii above the limb. Its normal incidence multilayer-coated optics
select spectral emission lines from FeIX (171 Ang), FeXII (195 Ang),
FeXV (284 Ang), and HeII (304 Ang) with 2.6 arcsecond resolution which
allow us to describe Solar activity over a wide temperature range. EIT
is providing unique EUV observations of the structure and evolution of
active regions. Here we show movies of active region 8059 from July
3-10, 1997. The high temporal variability of the AR loops is very
evident. Initial temperature and density diagnostics are explored as
well as a comparison with diagnostics from the SOHO-CDS instrument.
Title: Polar Plume Anatomy: Results of a Coordinated Observation
Authors: DeForest, C. E.; Hoeksema, J. T.; Gurman, J. B.; Thompson,
B. J.; Plunkett, S. P.; Howard, R.; Harrison, R. C.; Hasslerz, D. M.
Bibcode: 1997SoPh..175..393D
Altcode:
On 7 and 8 March 1996, the SOHO spacecraft and several other space-
and ground-based observatories cooperated in the most comprehensive
observation to date of solar polar plumes. Based on simultaneous
data from five instruments, we describe the morphology of the plumes
observed over the south pole of the Sun during the SOHO observing
campaign. Individual plumes have been characterized from the photosphere
to approximately 15 R⊙ yielding a coherent portrait of the features
for more quantitative future studies. The observed plumes arise from
small (∼ 2-5 arc sec diameter) quiescent, unipolar magnetic flux
concentrations, on chromospheric network cell boundaries. They are
denser and cooler than the surrounding coronal hole through which they
extend, and are seen clearly in both Feix and Fexii emission lines,
indicating an ionization temperature between 1.0-1.5 x 106
K. The plumes initially expand rapidly with altitude, to a diameter of
20-30 Mm about 30 Mm off the surface. Above 1.2 R⊙ plumes are observed
in white light (as `coronal rays') and extend to above 12 R⊙. They
grow superradially throughout their observed height, increasing their
subtended solid angle (relative to disk center) by a factor of ∼10
between 1.05 R⊙ and 4-5 R⊙ and by a total factor of 20-40 between
1.05 R⊙ and 12 R⊙. On spatial scales larger than 10 arc sec,
plume structure in the lower corona (R < 1.3 R⊙) is observed to
be steady-state for periods of at least 24 hours; however, on spatial
scales smaller than 10 arc sec, plume XUV intensities vary by 10-20%
(after background subtraction) on a time scale of a few minutes.
Title: EIT Observations of the Extreme Ultraviolet Sun
Authors: Moses, D.; Clette, F.; Delaboudinière, J. -P.; Artzner,
G. E.; Bougnet, M.; Brunaud, J.; Carabetian, C.; Gabriel, A. H.;
Hochedez, J. F.; Millier, F.; Song, X. Y.; Au, B.; Dere, K. P.; Howard,
R. A.; Kreplin, R.; Michels, D. J.; Defise, J. M.; Jamar, C.; Rochus,
P.; Chauvineau, J. P.; Marioge, J. P.; Catura, R. C.; Lemen, J. R.;
Shing, L.; Stern, R. A.; Gurman, J. B.; Neupert, W. M.; Newmark,
J.; Thompson, B.; Maucherat, A.; Portier-Fozzani, F.; Berghmans, D.;
Cugnon, P.; Van Dessel, E. L.; Gabryl, J. R.
Bibcode: 1997SoPh..175..571M
Altcode:
The Extreme Ultraviolet Imaging Telescope (EIT) on board the SOHO
spacecraft has been operational since 2 January 1996. EIT observes
the Sun over a 45 x 45 arc min field of view in four emission line
groups: Feix, x, Fexii, Fexv, and Heii. A post-launch determination
of the instrument flatfield, the instrument scattering function, and
the instrument aging were necessary for the reduction and analysis
of the data. The observed structures and their evolution in each
of the four EUV bandpasses are characteristic of the peak emission
temperature of the line(s) chosen for that bandpass. Reports on the
initial results of a variety of analysis projects demonstrate the range
of investigations now underway: EIT provides new observations of the
corona in the temperature range of 1 to 2 MK. Temperature studies of
the large-scale coronal features extend previous coronagraph work
with low-noise temperature maps. Temperatures of radial, extended,
plume-like structures in both the polar coronal hole and in a low
latitude decaying active region were found to be cooler than the
surrounding material. Active region loops were investigated in detail
and found to be isothermal for the low loops but hottest at the loop
tops for the large loops.
Title: Association of Extreme-Ultraviolet Imaging Telescope (EIT)
Polar Plumes with Mixed-Polarity Magnetic Network
Authors: Wang, Y. -M.; Sheeley, N. R.; Dere, K. P.; Duffin, R. T.;
Howard, R. A.; Michels, D. J.; Moses, J. D.; Harvey, J. W.; Branston,
D. D.; Delaboudinière, J. -P.; Artzner, G. E.; Hochedez, J. F.;
Defise, J. M.; Catura, R. C.; Lemen, J. R.; Gurman, J. B.; Neupert,
W. M.; Newmark, J.; Thompson, B.; Maucherat, A.; Clette, F.
Bibcode: 1997ApJ...484L..75W
Altcode:
SOHO EIT spectroheliograms showing the polar coronal holes during the
present sunspot minimum are compared with National Solar Observatory
(Kitt Peak) magnetograms taken in Fe I λ8688 and Ca II λ8542. The
chromospheric λ8542 magnetograms, obtained on a routine, near-daily
basis since 1996 June, reveal the Sun's strong polar fields with
remarkable clarity. We find that the Fe IX λ171 polar plumes occur
where minority-polarity flux is in contact with flux of the dominant
polarity inside each polar hole. Moreover, the locations of ``plume
haze'' coincide approximately with the patterns of brightened He
II λ304 network within the coronal hole. The observations appear
to be consistent with mechanisms of plume formation involving
magnetic reconnection between unipolar flux concentrations and nearby
bipoles. The fact that minority-polarity fields constitute only a small
fraction of the total magnetic flux within the polar holes suggests
that plumes are not the main source of the high-speed polar wind.
Title: Tracking a CME from Cradle to Grave: A Multi-wavelength
Analysis of the February 6-7, 1997 Event
Authors: Gopalswamy, N.; Kundu, M. R.; Hanaoka, Y.; Kosugi, T.; Hudson,
H.; Nitta, N.; Thompson, B.; Gurman, J.; Plunkett, S.; Howard, R.;
Burkepile, J.
Bibcode: 1997SPD....28.0501G
Altcode: 1997BAAS...29..908G
The partially earth-directed coronal mass ejection (CME) event of 1997
February 6-7 originated from the southwest quadrant of the sun. The
CME accelerated from 170 km/s to about 830 km/s when it reached a
distance of 25 solar radii. The CME was an arcade eruption followed
by bright prominence core structures. The prominence core was tracked
continuously from the solar surface to the interplanetary medium by
combining data from the Nobeyama radioheliograph (microwaves), Mauna Loa
Solar Observatory (He 10830 { Angstroms}), SOHO/EIT (EUV) and SOHO/LASCO
(white light). The CME was accompanied by an arcade formation, fully
observed by the YOHKOH/SXT (soft X-rays) and SOHO/EIT (EUV). The X-ray
and EUV observations suggest that the reconnection proceeded from
the northwest end to the southeast end of a filament channel. In the
SOHO/EIT images, the the feet of the soft X-ray arcade were observed
as EUV ribbons. The CME event also caused a medium sized geomagnetic
storm: The hourly equatorial Dst values attained storm level during
18:00-19:00 UT on February 09. This means the disturbance took about
2.25 days to reach the Earth. The first signatures of an IP shock was
a pressure jump in the WIND data around 13:00 UT on Feb 09, 1997 which
lasted for about 14 hours, followed by flux rope signatures. This CME
event confirms a number of ideas about CMEs: The three part structure
(frontal bright arcade, dark cavity and prominence core), disappearing
filament, elongated arcade formation, and terrestrial effects. We make
use of the excellent data coverage from the solar surface to the Earth
to address a number of issues regarding the origin and propagation of
the geoeffective solar disturbances. We benefited from discussions at
the first SOHO-Yohkoh Coordinated Data Analysis Workshop, held March
3-7, 1997, at Goddard Space Flight Center.
Title: Fitting a 3-d analytic model of the Coronal Mass Ejection
to observations
Authors: Gibson, Sarah; Fisher, Richard; Howard, Russ; Thompson,
Barbara
Bibcode: 1997SPD....28.0110G
Altcode: 1997BAAS...29..880G
We present the application of an analytic magnetohydrodynamic model
(Gibson and Low, 1997) to observations of the time-dependent expulsion
of three-dimensional Coronal Mass Ejections (CMEs) out of the solar
corona. The model relates the white-light appearance of the CME to
its internal magnetic field, which takes the form of a closed bubble,
filled with a partly anchored, twisted magnetic flux rope and embedded
in an otherwise open background field. The density distribution frozen
into the expanding CME magnetic field is fully three-dimensional, and
can be integrated along the line of sight to reproduce observations of
scattered white light. The model is able to reproduce the conspicuous
three features often associated with CMEs as observed with white-light
coronagraphs: a surrounding high-density region, an internal low-density
cavity, and a high-density core. By varying the model parameters,
including the location and orientation of the CME magnetic axis relative
to the limb, we are able to fit the model directly to examples of CMEs
observed by the HAO/SMM Coronagraph, the HAO/Mark III K-Coronameter,
and also to an event observed both by the SOHO/LASCO coronagraphs and
the SOHO/EIT EUV coronal imager.
Title: SOHO/EIT and SOHO/LASCO Observations of the April 1 1997 Event:
Coronal Observations of a Moreton Wave
Authors: Thompson, B. J.; Newmark, J. S.; Gurman, J. B.; St. Cyr,
O. C.; Stezelberger, S.
Bibcode: 1997SPD....28.0130T
Altcode: 1997BAAS...29..884T
The SOHO Extreme ultraviolet Imaging Telescope (EIT) recorded a series
of events on April 1, 1997 with a 12-minute cadence of 195 Angstrom
(Fe XII) images. A Moreton wave was observed emanating from a flaring
active region beginning at 13:56 UT 1-April-1997. The wave travelled
at initial speeds of approximately 300 km/sec, spreading across the
solar disk radially from the flare. The CME observed by SOHO/LASCO was
observable at both the east and west limbs in the C2 (2-6 solar radii)
and C3 (3.7-30 solar radii) coronagraphs. The event was the site of
strong emerging flux, and a number of explosive jet-like surges were
observed at the east edge of the region prior to, throughout, and
following the event. The discussion will include topology, comparison
to Moreton wave/MHD theory predictions, and solar wind signatures.
Title: Observations of the January 6, 1997 CME/Magnetic Cloud Event
Authors: Thompson, B. J.
Bibcode: 1997SPD....28.0302T
Altcode: 1997BAAS...29..907T
Despite the unprecedented degree of scientific coverage, the solar
origin of the January 6, 1997 CME/Magnetic Cloud Event is not completely
understood. The eruption was associated with a small disappearing
filament and long duration event (LDE) but was accompanied by no
significant CME signatures in soft x-ray and radio data. SOHO/LASCO
images of the event showed a faint CME encompassing 3/4 of the solar
disk. This event is of interest for (at least) three reasons: the
event had a significant impact on geospace, causing activity which
was detectable throughout the entire magnetosphere. Secondly, it
adds another event to the list of eruptions which are surprisingly
subtle in the solar data but are extremely geoeffective. Finally,
the event was observed with historic completeness: from its origin
(coronagraph/solar disk imagers), propagation (WIND/WAVES radio
tracking), magnetospheric impact, and subsequent geomagnetic
activity. The presentation will include a discussion of the current
progress towards the understanding of these events and a summary of
the solar, solar wind, and magnetospheric observations.
Title: Observations of Coronal Features by EIT above an Active Region
by EIT and Implications for Coronal Heating
Authors: Neupert, W. M.; Newmark, J.; Thompson, B. J.; Catura, R.;
Moses, J. D.; Portier-Fozzani, F.; Delaboudiniere, J. P.; Gabriel, A.;
Artzner, G.; Clette, F.; Cugnon, P.; Maucherat, A.; Defise, J. M.;
Jamar, C.; Rochus, P.; Howard, R.; Michels, D.; Dere, K.; Freeland,
S.; Lemen, J.; Stern, R.; Gurman, J.
Bibcode: 1997SPD....28.0115N
Altcode: 1997BAAS...29..881N
The EUV Imaging Telescope (EIT) on the SOHO provides the capability
for multi-wavelength imaging of the corona in four spectral bands,
centered at 171, 195, 284, and 304 Angstroms, using multilayer telescope
technology. These bands encompass coronal temperatures from 1 MK
to 2.5 MK as well as the upper chromosphere, at about 60,000 K. In
particular, nearly simultaneous imaging in the 171 and 195 Angstrom
bands, the former including major Fe IX and Fe X emission lines, the
latter including a strong Fe XII line, provides a capability to infer
the morphology and characteristics of the corona at temperatures of
1.0 - 1.7 MK. We have examined the corona in this temperature range
over an active region observed from SOHO from May - September, 1996 and
find that low-lying loops (below a density scale height of 75,000 km,
characteristic of Fe X) vary little in brightness and temperature along
their length. For features extending to greater heights, however, both
brightness gradients and temperature gradients are observed. Preliminary
analysis of the observations when the region was on the West limb
on September 30 indicates a small positive temperature gradient of
approximately 0.5 K/km in one loop system that extended above 100,000
km. On the other hand, a nearly radial feature extending to the edge of
the EIT FOV was isothermal or had at most a slight negative temperature
gradient. Such measurements may have application to the modeling of
coronal loops and streamers and the processes of coronal heating and
solar wind acceleration.
Title: The Solar Minimum X2. 6/1B Flare and CME of 9 July 1996;
Part 1: Solar Data
Authors: Andrews, M. D.; Dryer, M.; Aurass, H.; DeForest, C.;
Kiplinger, A. L.; Meisner, R.; Paswaters, S. E.; Smith, Z.; Tappipn,
S. J.; Thompson, B. J.; Watari, S. I.; Lamy, P.; Mann, G.; Schwenn,
R.; Michels, D. J.; Brueckner, G. E.; Howard, R. A.; Koomen, M.
Bibcode: 1997ESASP.404..169A
Altcode: 1997cswn.conf..169A
No abstract at ADS
Title: A Multi-Wavelength Analysis of the February 6/7, 1997 Coronal
Mass Ejection
Authors: Plunkett, S. P.; Gopalswamy, N.; Kundu, M. R.; Howard, R. A.;
Thompson, B. J.; Gurman, J. B.; Lepping, R. P.; Hudson, H. S.; Nitta,
N.; Hansoka, Y.; Kosugi, T.; Burkepile, J. T.
Bibcode: 1997ESASP.404..615P
Altcode: 1997cswn.conf..615P
No abstract at ADS
Title: Solar Magnetic Field Events related to CMEs observed with SOHO
(MDI, EIT, SUMER, LASCO)
Authors: Schmieder, B.; van Driel-Gesztelyi, L.; Wiik, J. E.; Thompson,
B.; de Forest, C.; Saint Cyr, C.; Vial, J. -C.; Nitta, N.; Simnett, G.
Bibcode: 1997IAUJD..19E..42S
Altcode:
We shall present two CMEs observed by LASCO during the minimum of
activity of the Sun. These are associated with filament disparitions
brusques (DB). CME and DB definitively seem to be consequences of global
magnetic field instability, which causes reconnection of pre-existing
field lines in the corona. We shall demonstrate how cancelling flux
and converging magnetic field in photosphere may destabilize coronal
streamers overlying one or two filament channels.
Title: First Results from SOHO on Waves Near the Solar Transition
Region
Authors: Steffens, S.; Deubner, F. -L.; Fleck, B.; Wilhelm, K.;
Schuhle, U.; Curdt, W.; Harrison, R.; Gurman, J.; Thompson, B. J.;
Brekke, P.; Delaboudiniere, J. -P.; Lemaire, P.; Hessel, B.; Rutten,
R. J.
Bibcode: 1997ASPC..118..284S
Altcode: 1997fasp.conf..284S
We present first results from simultaneous observations with the
CDS, EIT and SUMER instruments {please see Solar Physics 162 (1995)
for a description of the instruments} onboard SOHO and the VTT at
Tenerife. Our aim is to study the wave propagation, shock formation,
and transmission properties of the upper chromosphere and transition
region. The preliminary results presented here include the variation
of velocity power spectra with height, difference in power between
internetwork and network regions, and variations in mean flows displayed
by different spectral lines.
Title: SOHO EIT Carrington Maps from Synoptic Full-Disk Data
Authors: Thompson, B. J.; Newmark, J. S.; Gurman, J. B.;
Delaboudiniere, J. P.; Clette, F.; Gibson, S. E
Bibcode: 1997ESASP.404..779T
Altcode: 1997cswn.conf..779T
No abstract at ADS
Title: The Solar Minimum X2. 6/1B Flare and CME of 9 July 1996;
Part 2: Propagation
Authors: Dryer, M.; Andrews, M. D.; Aurass, H.; DeForest, C.; Karlicky,
M.; Kiplinger, A.; Klassen, A.; Meisner, R.; Ipavich, F. M.; Galvin,
A. B.; Paswaters, S. E.; Smith, Z.; Tappin, S. J.; Thompson, B. J.;
Watari, S. -I.; Michels, D. J.; Brueckner, G. E.; Howard, R. A.;
Koomen, M. J.; Lamy, P.; Mann, G.; Arzner, K.; Schwenn, R.
Bibcode: 1997ESASP.404..331D
Altcode: 1997cswn.conf..331D
No abstract at ADS
Title: Prominence Activity Related to CME Observed by SOHO, YOHKOH
and Ground-Based Observatories
Authors: Schmieder, B.; van Driel-Gesztelyi, L.; Wiik, J. E.; Kucera,
T.; Thompson, B.; de Forest, C.; Saint Cyr, C.; Simnett, G. M.
Bibcode: 1997ESASP.404..663S
Altcode: 1997cswn.conf..663S
No abstract at ADS
Title: Scientists track solar event all the way to Earth
Authors: Peredo, M.; Fox, N.; Thompson, B.
Bibcode: 1997EOSTr..78..477P
Altcode:
For the first time ever, the satellites of the International
Solar-Terrestrial Physics (ISTP) “Observatory” have tracked a solar
eruption all the way from the Sun to the Earth. The resulting coronal
mass ejection (CME) traveled 4 days through interplanetary space before
arriving at Earth, where it caused violent disturbances of the magnetic
environment and spectacular auroral displays. The initial expulsion
occurred on the Sun on January 6, 1997, and the resulting magnetic
cloud hit the Earth on January 10.The Sun often erupts. It flings out
whitehot ionized gas (actually hotter than whitehot, to where it glows
in X rays) with explosive violence. Only occasionally is this gas
aimed at Earth, however, and it is even more unusual for scientists
to be watching the potentially disruptive mass ejection (as they were
in January) just as it leaves the Sun. This made it possible to alert
other scientific teams of possible activity they might observe 2 to 3
days later. It normally takes that long for such ejecta to travel the
150-million-km void from Sun to Earth. Thus while this is not the first,
or the largest, event to be detected, the ISTP Observatory comprises
a complement of spacecraft and ground-based missions that allows study
of this “space storm” on a scale never accomplished before.
Title: A Search for the Coronal Origins of Fast Solar Wind Streams
During the Whole Sun Month Period
Authors: Lazarus, A. J.; Steinberg, J. T.; Biesecker, D. A.; Forsyth,
R. J.; Galvin, A. B.; Ipavich, F. M.; Gibson, S. E.; Lecinski, A.;
Hassler, D. M.; Hoeksema, J. T.; Riley, P.; Strachan, L., Jr.; Szabo,
A.; Lepping, R. P.; Ogilvie, K. W.; Thompson, B. J.
Bibcode: 1997ESASP.404..511L
Altcode: 1997cswn.conf..511L
No abstract at ADS
Title: Modeling a Simple Coronal Streamer during Whole Sun Month
Authors: Gibson, S. E.; Bagenal, F.; Biesecker, D.; Guhathakurta,
M.; Hoeksema, J. T.; Thompson, B. J.
Bibcode: 1997ESASP.404..407G
Altcode: 1997cswn.conf..407G
No abstract at ADS
Title: Microwave and UV observations of filaments with SOHO and
the VLA
Authors: Alissandrakis, C. E.; Drago, F.; Bastian, T.; Bocchialini,
K.; Delaboudiniere, J. -P.; Lemaire, P.; Vial, J. -C.; Harrison,
R. A.; Thompson, B.
Bibcode: 1997ASPC..118..289A
Altcode: 1997fasp.conf..289A
Observations performed in coordination between SOHO instruments and
ground-based observatories offer the unique possibility to derive
information simultaneously in several wavelengths formed at different
altitudes and/or temperatures in the solar atmosphere. The SUMER and
CDS spectrometers, the imaging telescope EIT aboard SOHO, and the VLA
provide complementary information in the UV and the radio ranges. We
illustrate such a coordination with observations of filaments in the
transition region, performed in July 1996. The observations in the UV
between 10(4) and 10(6) K provide the differential emission measure
as a function of temperature; this can be used to compute the expected
brightness temperature in the microwave range and check models of the
filament-corona transition region.
Title: An Equatorial Coronal Hole at Solar Minimum
Authors: Bromage, B. J. I.; Del Zanna, G.; DeForest, C.; Thompson,
B.; Clegg, J. R.
Bibcode: 1997ESASP.404..241B
Altcode: 1997cswn.conf..241B
No abstract at ADS
Title: Electron acceleration by inertial Alfvén waves
Authors: Thompson, B. J.; Lysak, R. L.
Bibcode: 1996JGR...101.5359T
Altcode:
Alfvén waves reflected by the ionosphere and by inhomogeneities in
the Alfvén speed can develop an oscillating parallel electric field
when electron inertial effects are included. These waves, which have
wavelengths of the order of an Earth radius, can develop a coherent
structure spanning distances of several Earth radii along geomagnetic
field lines. This system has characteristic frequencies in the range of
1 Hz and can exhibit electric fields capable of accelerating electrons
to several keV. These electric fields have the potential to accelerate
electrons in several senses: via Landau resonance, bounce or transit
time resonance as discussed by André and Eliasson [1992] or through
the effective potential drop which appears when the transit time
of the electrons is much smaller than the wave period, so that the
electric fields appear effectively static. A time-dependent model of
wave propagation is developed which represents inertial Alfvén wave
propagation along auroral field lines. The disturbance is modeled as it
travels earthward, experiences partial reflections in regions of rapid
variation, and finally reflects off a conducting ionosphere to continue
propagating antiearthward. The wave experiences partial trapping
by the ionospheric Alfvén resonator, which is the effective cavity
formed between the ionosphere and the Alfvén speed peak discussed
earlier by Polyakov and Rapoport [1981] and Trakhtengerts and Feldstein
[1981, 1984, 1991] and later by Lysak [1991, 1993]. Results of the wave
simulation and an accompanying test particle simulation are presented,
which indicate that inertial Alfvén waves are a possible mechanism
for generating electron conic distributions and field-aligned particle
precipitation. The model incorporates conservation of energy by allowing
electrons to affect the wave via Landau damping, which appears to
enhance the effect of the interactions which heat electron populations.
Title: Some dynamical aspects of a quiescent filament
Authors: Schmieder, B.; Demoulin, P.; Poland, A.; Thompson, B.
Bibcode: 1988A&A...197..281S
Altcode:
A typical quiescent filament was observed on the disk in the Hα
and C IV lines during a period of approximately one hour. Vertical
velocities (<2.5 km s-1) with a time scale of 5 min and
a spatial scale of a few tens of seconds of arc were detected in Hα,
and associated with microturbulence in both lines. The C IV observations
correlated well with those in Hα, and showed no indication of material
heating from Hα to C IV temperatures. Two mechanisms to explain these
observations are proposed: mass motion along twisted magnetic field
or instabilities triggering waves along the filament.
Title: James Harland Duthie died 13 October 1986.
Authors: Thompson, B.
Bibcode: 1987SouSt..32..102T
Altcode:
No abstract at ADS
Title: Applied optics and optical engineering. Vol._VI.
Authors: Kingslake, R.; Thompson, B. J.
Bibcode: 1980aooe.book.....K
Altcode:
No abstract at ADS
Title: REVIEW: Applications of holography
Authors: Thompson, B. J.
Bibcode: 1978RPPh...41..633T
Altcode:
The current status of holography and its applications are discussed
with some historical background to place the current activity in
perspective. Basic types of holograms are described together with
their properties. Applications in optical image formation include
photography, microscopy, image storage and image replication. Acoustic,
X-ray, electron beam and microwave holography are briefly commented
upon. The second major area of application is contour generation and
interferometry. Finally, the current status of holographic optical
elements is assessed.
Title: Recovery of Images from Atmospherically Degraded Short-Exposure
Photographs
Authors: Knox, K. T.; Thompson, B. J.
Bibcode: 1974ApJ...193L..45K
Altcode:
The possibility is shown that the phase of an object transform can
be determined from the autocorrelation of the image transform. The
two together should give a diffraction-limited image of the object. A
thereon based technique for the recovery of images from atmospherically
degraded short-exposure photographs is proposed. Results from a
one-dimensional computer simulation are used for a preliminary
demonstration of the technique.
Title: Space optics. Proceedings of the 9th International Congress
of the International Commission for Optics.
Authors: Thompson, B. J.; Shannon, R. R.
Bibcode: 1974sop..book.....T
Altcode:
No abstract at ADS
Title: Space optics
Authors: Thompson, B. J.; Shannon, R. R.
Bibcode: 1974spop.conf.....T
Altcode:
No abstract at ADS
Title: Removal of turbulence from short-time-exposure photographs
of star images.
Authors: Knox, K. T.; Thompson, B. J.
Bibcode: 1973JOSA...63.1326K
Altcode:
No abstract at ADS
Title: Fraunhofer Holography for Bubble Chamber Photography
Authors: Thompson, B. J.; Ward, J. H.
Bibcode: 1967moop.conf..649T
Altcode:
No abstract at ADS