Annual Report: Understanding Magnetic Eruptions on the Sun and their Interplanetary Consequences: August 1 2001 – June 30 2002[1]
PI: George H. Fisher
AFOSR Grant F49620-01-1-0360
Notable accomplishments of our MURI award over the past year include these major developments:
This annual report is organized as follows: We first provide a brief exposition of several of the major accomplishments identified above, followed by 4 detailed, chronological quarterly reports that were provided by all 9 University Teams over the course of the year. Finally, at the end of the report, we provide a list of publications funded in part or in full by the Solar MURI project.
Efforts like the MURIs are important in that they provide a rare opportunity to get new talent into targeted fields, such as the solar origins of Space Weather. The Solar MURI grant has resulted in these new hires:
Brian Welsch, a recent PhD graduate of the Physics Department at Montana State University, was hired as a new postdoc at UC Berkeley to work on scientific topics related to Solar MURI. He is also collaborating closely with Spiro Antiochos, Rick Devore, and Mark Linton at the Naval Research Laboratory in Washington DC, and spends significant time each year at NRL. Brian is pursuing a project aimed at understanding whether shearing and reconnection of a simple bipolar active region can lead to an erupting flux-rope configuration. This project is an outgrowth of the “Numerical Experiments” MURI workshop that was held at UNH earlier this year (and described further below).
Andrew Phillips is a new postdoc at Drexel University working for Peter MacNeice. He began work in mid February, after finishing a PhD degree in the UK. He has been developing a Sedov test of the hydrodynamics of a High Order Godunov code using the Paramesh adaptive mesh refinement algorithm.
Jimin Gao is a graduate student interested in computational physics that is working with MacNeice on the Solar MURI project.
Stephane Regnier is a new postdoc at Montana State University, working with Dick Canfield and Dana Longcope. He received his PhD recently in France, and is now working with Canfield & Longcope on the reduction of vector magnetograms, the development of coronal force-free-field models based on the magnetogram data, and comparison of the theoretical models with solar coronal observations. He is playing a key role in the use of observed data in NOAA region 8210 to drive MHD simulations of magnetic eruptions.
Yong-Jae Moon is a new postdoc at BBSO/NJIT. He has expertise in the analysis of data from solar flares and CMEs, and the use of vector magnetograph data. He has been an especially prolific contributor to MURI funded publications over the past year.
Adaptive mesh refinement (AMR) is essential if one wishes to simultaneously resolve small scale structures on the Sun and large scale structures in the outer corona and the heliosphere. Therefore one of the goals we set for ourselves at the beginning of the Solar MURI project was to use the expertise of Peter MacNeice, one of the originators of the Paramesh AMR and domain decomposition software, to help integrate Paramesh into our already existent numerical MHD codes, Zeus-3D (corona) and ENLIL (heliosphere). This process was begun during a 1 week mini-workshop at GSFC during July of 2001, attended by Odstrcil, Abbett, Ledvina, & MacNeice, and was successfully completed this year. In addition to the inclusion of Paramesh, Abbett & Ledvina incorporated other improvements into Zeus-3D, such as the elimination of operator splitting in the transport step (an improvement originally implemented by Yuhong Fan of HAO), which improved the code’s efficiency and accuracy. Abbett & Ledvina have dubbed their new version of ZEUS ``ZeusAMR”.
Abbett also worked to include
a much more physically consistent coupling between our interior MHD code,
ANMHD, which is used for simulations of the solar interior, and Zeus-3D and
ZeusAMR. An example of the computed
evolution of the emergence of an active region, performed with ANMHD and
Zeus-3D is shown in Figures 1. The left
hand side of Figure 1 shows how the 2 codes are coupled together in space,
while the right hand side shows a comparison between the MHD solution and a
potential field solution with increasing time for an emerging, twisted active
region flux with different levels of twist within each tube.
Figure 1 – Bottom red box on left shows the volume encompassed by the ANMHD simulation of an emerging, twisted active region flux tube rising though the solar interior toward the solar surface. The grey plane and the field lines above it show the Zeus-3D simulation of the response of the solar corona to the emerging flux. The 6 images on the right hand side show comparisons between the MHD simulations of coronal evolution and a potential field extrapolation. The left hand column shows the MHD results, and the right hand column the potential field extrapolation. Each row shows a different amount of twist in the emerging active region flux tube, with the top row corresponding to no initial twist, and the bottom row to substantial twist. These results are presented in a paper by Abbett & Fisher to be published in ApJ on January 1 2003.
Improvements to the ANMHD code were made as a collaboration between team member Abbett and Yuhong Fan of HAO, while they were both participants in the “Origins of Solar Magnetism” program at the Institute for Theoretical Physics at UCSB. The ANMHD source code is publicly available on our Solar MURI website as the file Anmhd.tar.gz in the directory http://solarmuri.ssl.berkeley.edu/~abbett/public/software/ .
An illustration of a similar
calculation performed with ZeusAMR, exhibiting the use of a block adaptive
mesh, is shown in Figure 2. 
Figure 2 – Emerging flux simulation showing field lines (white) and vertical velocity contours in a single vertical plane (blue). Mesh size is shown as the checkerboard patterns. The adaptive mesh allows for a large dynamic range in size scales.
Simulations such as these can
also be incorporated in a fairly straightforward way into simple source surface
models of the large-scale corona.
Figure 3 shows how one of Abbett’s emerging active regions affects an
initially dipolar magnetic field on the Sun and how the active region changes
the location of the coronal hole boundaries.
Figure 3 – illustration of how an emerging active region simulation can be used to study its effects on an initially simple dipolar solar magnetic field. Note the distortion of the northward coronal hole toward the active region. A similar configuration resulted in the famous “elephant trunk” coronal hole in 1996 when a large active region formed at low latitudes near solar minimum.
During a 1 week visit by Dusan Odstrcil to Berkeley in August of 2002, Ledvina & Odstrcil settled on a code-coupling framework for connecting ZeusAMR simulations of the outer corona with ENLIL simulations of the heliosphere. To facilitate this coupling, a spherical version of ZeusAMR is being developed and tested.
It was clear early on that many of the problems that must be solved to achieve a solar and heliospheric numerical modeling system are too complex to be tackled by individual researchers working alone. We therefore decided to organize a series of focused workshops to tackle what we regarded as the most pressing problems in modeling the solar origins of space weather. At this point, we have held 4 of these workshops, and plan to hold 2 more: UH team members are hosting a workshop in Honolulu Nov. 18-20 on the use of the new coronal IR / magnetic field measurements to be made on Haleakala, and how to make best use of this new data in our theoretical and numerical modeling efforts. Jozsef Kota, Janet Luhmann, and Marty Lee are organizing one on SEP acceleration to be held at the University of Arizona March 17-18 of 2003.
The first of the workshops held this past year was on the
Paramesh adaptive mesh and domain decomposition tool, which has now been
successfully incorporated in both ZeusAMR and ENLIL. It was the success of that workshop that led us to organize 3
more – one on the construction of synoptic magnetic maps, one on the use of
vector magnetograms to drive numerical models of the corona, and a workshop on
numerical experiments for CME initiation.
This one-day workshop was held in Boulder, CO just before Space Weather Week. The workshop was organized by team member Bernie Jackson, and was attended by scientists from both MURI teams, as well as participants from SEC/NOAA.
Synoptic maps of the
photospheric field distribution remain the sole quantitative observational
input for coronal and solar wind models and thus are key to the success of
Sun-Earth modeling efforts.
Although digital
synoptic maps of the photospheric field distribution are now routinely
available from a number of solar observatories (e.g., Mount Wilson, Wilcox, and
National (on Kitt Peak), the methods and processing used to construct them
differ considerably, as do their archive file formats, spatial resolutions, and
physical data units. This general lack of uniformity makes it very tedious and
cumbersome for users to switch back and forth between synoptic maps generated
by different facilities (data gaps being a prime example as to why such a switch
might be necessary).
As more groups coordinate their research efforts by studying specific events and as more models are run in a (near) real-time mode, the ability to use uniformly assembled synoptic maps from multiple observatories is becoming increasingly critical. The solar and heliospheric communities would benefit from a reliable, centrally located public site providing synoptic maps (from multiple observatories) which have a uniform file format and which have been constructed using an established and documented assembly technique.
Over the last few
years, through support from ONR, NSF, and NASA, a generalized synoptic map
assembly code has been developed by Nick Arge at NOAA/SEC. This code can merge
line-of-sight magnetograms from virtually any solar observatory into daily
updated and full Carrington synoptic maps, as well as other types. It is
versatile in that it provides greater control over how the maps are constructed
and as to what corrections (unique to each observatory) need to be applied to
the magnetic field data. It is thus ideally suited to provide the solar
community with a standardized set of synoptic maps. In addition, the model is
housed at a facility (NOAA/SEC) that is both reliable and readily accessible to
the public. The ready availability of regularly updated, uniformly constructed
synoptic maps from several observational sources will significantly facilitate
the development of Sun-Earth propagation modeling capabilities.
Vector Magnetogram Workshop (April 29-May 1 2002)
The workshop was held at SSL/UC Berkeley, and was organized by Dick Canfield and George Fisher. It was attended by MURI team members, and by other experts on vector magnetogram data (Tom Metcalf [LMSAL] and KD Leka [CoRA], as well as Zoran Mikic [SAIC]). Here is the resulting “plan of action”:
Phase I
.

Figure 4 – vertical magnetic field map of AR 8210 with all magnetic flux concentrations labeled (courtesy Dana Longcope).
Phase II. Carry out MHD simulations
1.
Do Zeus AMR
simulations using real magnetic field data near time of CME using synoptic
magnetic field solutions as boundary condition. (Berkeley team members)
2.
Couple coronal
and interplanetary codes (Abbett, Ledvina, Odstrcil)
Phase III. Validation of modelling using available
solar and IP data (team)
Numerical
experiments to understand CME initiation:
(Workshop held
May 14-16 at UNH in Durham)
This workshop was
organized by Terry Forbes, and was attended by many members of both the Michigan
and Berkeley MURI teams, as well as scientists from AFRL and NRL.
The objective of the
workshop was to define the most urgent numerical MHD simulations needed to
understand the physics of magnetic field eruption on the Sun (ie CME
initiation). What emerged were 3
different classes of investigation that the participants felt were
necessary. These are outlined below in
a very skeletal form.
o 3-d Emerged Bipole: Form a flux-rope in a simulated corona by converging footpoints of coronal fields (analogous to “flux cancellation” seen near neutral lines in filament channels)
o
the
computational domain is 3-d non-periodic box with high b =
10?) on bottom boundary, with stratification such that b << 1
within lower part of simulation volume.
o
initial
condition (IC) has volume-filling dipole field.
o
impose
incompressible converging flows on bottom boundary (if initial configuration is
slightly twisted) or converging flows with shear (if initial configuration is
untwisted).
o Flux rope in coronal volume is formed via the emergence of a pre-existing twisted flux tube from a region of high b to low b
o Initial conditions: buoyantly unstable horizontal twisted flux tube immersed in high-b plasma at base of gravitationally stratified 3-d box.
o Follow rise of twisted flux tube from deep in convection zone through photosphere into corona. Critical issue: initial position of tube cannot be too near surface, as flux tube curvature matters.
o Unspecified parameter: degree of twist in emerging tube. Twist too high perhaps prevents mass drainage, hampering emergence; twist too low does not give true flux rope in corona.
o Unspecified parameter: Magnetic field configuration in corona prior to flux rope emergence. Initial runs w/field-free corona envisioned.
o As above, primary goal is to get flux rope in
corona; subsequent efforts to attain eruption envisioned after attainment of
primary.
o As above, some modification of existing codes necessary.
III. Emergence Within a
Multi-Polar Configuration
Emerge one flux tube into into a background magnetic field; the sheared arcade/flux rope formation is by reconnection between emerging flux and pre-existing flux.
§
Initial
conditions: buoyantly unstable flux tube immersed in high-b plasma at base of gravitationally stratified
3-d box with background magnetic field configuration composed of a pre-emerged
flux tube and large scale “restraining field”, and form sheared arcade/flux
rope by reconnection between the two flux tubes. The critical issue: without restraining field, reconnected flux
expected to rise to top of computational volume in non-explosive manner.
§
Primary goal is
attainment of sheared arcade/flux rope in corona; subsequent effort to attain
eruption envisioned.
§
In one effort
to attain eruption, additional polarity will be added to restraining field to
make it quadrupolar.
Unspecified parameter: twist in either pre-emerged or newly-emerging flux ropes. Presence of twist might either enhance or diminish storage of energy in the field, and hence likelihood of eruption.
The full specification of all the necessary magnetic elements for this class of simulations is illustrated with the simple diagram below:

Figure 5 – an illustration of the full multi-polar configuration for the 3rd class of numerical experiments. Initially, only the interaction between the two central bipoles (one pre-existing, the other emerging) will be considered. The magnetic neutral line between them is shown as the dashed curve. An additional overlying, constraining bipole field will then be considered; finally, a very large-scale bipole with the opposite polarity will be added. The last bipole can be considered as a schematic representation of the overall solar dipole field. This last level of complexity is necessary to create magnetic null points in the corona and hence achieve a “breakout” topology.
Deriving Self-Consistent Velocities from Sequential Vector Magnetograms
One of the major technical obstacles identified at the vector magnetogram workshop was determining the physically self-consistent vector velocity field at the surface where vector magnetic fields are measured. Dana Longcope (MSU) has achieved a major breakthrough on this problem, and has created a mathematical framework to describe the problem and has proposed a solution, and written an “alpha” version of an IDL procedure to implement the solution. The details of Dana’s formalism can be found on the Solar MURI website at http://solarmuri.ssl.berkeley.edu/~dana/public/presentations/ as SHINE02.ps . Current versions of the IDL software can be found in the “team” part of the website as http://solarmuri.ssl.berkeley.edu/~dana/team/software/ . Shown below is a comparison of the velocity field from a real MHD simulation of flux emergence, and that derived using Dana’s inversion technique.
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|
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Figure 6 – Comparison between velocity field from an MHD simulation (left) and the reconstructed velocity field using Longcope’s inversion technique (right)
OVERVIEW
OF ACCOMPLISHMENTS FOR PAST 2 MONTHS
Major
progress was made in numerical modeling capabilities over the past 2 months,
with both the solar coronal (ZeusAMR) and heliospheric MHD codes (ENLIL) being
upgraded to include adaptive mesh refinement.
These efforts are not complete, but the codes are running and are
currently being debugged and tested.
Observational
efforts continued at BBSO, UH, MSU, and UCB, with Yan Li and Dick Canfield
continuing their efforts to construct a database of well-observed CMEs for in
depth studies, and BBSO conducting a coordinated flare campaign.
Instrument
construction, repair, and upgrades continue at BBSO and UH.
New papers
were reported by Jing et al. (UH), Wang et al. (BBSO).
The Solar
MURI website and data sharing server was set up and is now operational; the URL
is http://solarmuri.ssl.berkeley.edu
. All Solar MURI team members should have received email about how to use the
data sharing aspects of the website, as well as how to log in and what the
passwords are. If a login account for
new MURI team members is necessary, please contact George Fisher
(fisher@ssl.berkeley.edu) or Bill Abbett (abbett@ssl.berkeley.edu).
Detailed
descriptions of work accomplished at each institution now follow. In the plain text, emailed version of this
report, the Figures will be included as attachments (.jpg or .gif images),
while the web-page version, which should appear within the next few days, will
have the figures incorporated into the report itself. You should find 3 Figures attached to this email message, in
addition to the text itself.
Steve
Ledvina and Bill Abbett have worked on combining the PARAMESH adaptive mesh algorithm with the ZEUS 3D MHD code after attending our ``Paramesh''
mini-workshop with MacNeice and
Odstrcil at GSFC in July. They have
succeeded in getting the combined new
code (dubbed ``ZeusAMR'') to run, and are performing a series of test
simulations. This effort involved a
significant re-write of the underlying
ZEUS
code. The ZeusAMR code will eventually
be used for both large and small scale
coronal simulations. Abbett, Ledvina, Fisher, and MacNeice have submitted an
AGU abstract describing this work for the Fall 2001.
Yan Li
worked with Dick Canfield at Montana State University on the continuing
construction of the MURI case studies data access website. She has also started
to make the MDI magnetogram data sets to be linked to this table. These data
are also available as movies made to show the time evolution of the active
regions in the full-disk field context, see http://sprg.ssl.berkeley.edu/~yanli/mdicrmovs.html
. An abstract has been submitted to the Fall AGU meeting on the work described
in the previous monthly report, involving the response of global potential
field models to Bill Abbett's modeled emergence of active region fields.
Janet
Luhmann is examining the helmet streamer belt configuration at times of CMEs
and the location of the involved active region with respect to the helmet
streamer belt. This work relates to understanding both global coronal context
of CMEs and CME initiation in future global MHD models. An abstract on this has
also been submitted for the Fall AGU meeting.
George
Fisher and Neil Griffiths have mostly completed the Solar MURI web site, http://solarmuri.ssl.berkeley.edu
, and have set up a new server to host the web page, as well as to serve as a
centralized exchange for data and other information pertinent to the Solar MURI
project.
BBSO/NJIT
Contributions - Report received from Peter T. Gallagher
(1)
Coordinated Flare Observations: During August, we coordinated a week-long
campaign to search for impulsive chromospheric Doppler shifts associated with
large solar flares. Two simultaneously
clocked 50 Hz CCD cameras were set up on two orthogonal benches of the 65-cm
telescope at BBSO. Light from the telescope was directed to each bench by a
50:50 beamsplitter, and then to two H-alpha Lyot filters tunned to H-alpha line
center +/- 0.3 A. In conjunction with these data, high-sensitivity vector magnetograms
were simultaneously obtained using the Digital Vector Magnetograph (DVMG). We
are currently in the process of reducing and analysing the data.
(2) Max
Millennium Flare Catalogue: Software was completed to format the observing logs
from the Owen's Valley Solar Array
(OVSA) and the BBSO lead Global H-alpha
Network for the Max Millennium Flare Catalog.
(3)
Visible-Light Fabry-Perot: Control software is now being developed to
synchronize the Queensgate ET-50 Fabry-Perot with an SMD 1M60 camera. The
system will be moved to the dome for testing in October or November.
(4)
Publications: Wang et al. published a paper entitled "Inter-Active
Region Connection of Sympathetic
Flaring on 2000 February 17". The paper appeared in the 2001 October 1
issue of ApJ.
Drexel
University - Report received from Peter MacNeice.
We
continued development work on our existing CME
`breakout' model code, continued development work on a High Order
Godonov version, and interviewed candidates for a post-doctoral position in
support of this project.
Previously
we implemented a number of fixes to handle a numerical cavitation problem which
had appeared in high resolution runs of the ARC_FCT2.5D_AMR code. These fixes seem to be a source of
instability, which we have been attempting to characterize.
Mr. Jimin
Gao has been working to generate a more general initial field configuration for
the numerical model. Specifically, we have generated a multipole field which
will enable us to test the breakout model in 2.5D by applying shear away from
the equator.
Mr. Jimin
Gao has designed a test problem for the high order Godonov code under
development, using the Sedov-Taylor analytic solution for a large point
explosion in 3D.
We
conducted phone interviews with four candidates for a post-doctoral position
that will support this project.
Montana
State University - Report received from Dana W. Longcope.
To choose
appropriate case studies for the observational part of our project, it is
necessary to gather information -- which regions are well observed from the
point of view of modeling? For this
purpose, Canfield worked with Yan Li (UCB) to add Robert Leamon's extensive
list of eruptions from sigmoids to her Solar MURI event list. Although the two
lists have not yet been integrated, Yan Li has now put Leamon's list on the
web: http://sprg.ssl.berkeley.edu/~yanli/muri/sigmoid.table.html
.
Canfield
and MSU undergraduate Zachary Holder started a web page that documents the
availability of Hawaii vector magnetograms for events in Yan Li's event
list: http://solar.physics.montana.edu/muri/vec/
. Our next job is to identify vector
magnetograms that are relevant to events in Leamon's list and add them to this
web page.
Piet
Martens submitted an abstract and prepared a paper for the Yohkoh 10 meeting,
but its delivery has been postponed to January. He has been reading up on recent Big Bear papers on onset and
triggers of filament eruptions.
Dana
Longcope began work with Stephan Regnier, who will begin Post Doctoral research
under MURI funding in November. The two
set about comparing topologies found using full MHD extrapolation to those
found using Magnetic Charge Topology models.
Active region 8151 was selected since Regnier had previously performed
extrapolations of this region. The
comparisons will later be perfomed on regions selected from MURI event list.
The
following paper, which was reported as ``in press'' at the last bi-monthly
report, has now been published:
"Origin
and Evolution of Filament-Prominence Systems", P.C.H. Martens and C. Zwaan
2001, Astrophys. J., 558, 872-887
Stanford
Contributions - Report received from Yang Liu.
In the past
two months from August 1 to September 30, we have tested our method to generate
the Carrington synoptic maps using vector photospheric magnetic field in place
of the light-of-sight photospheric magnetic field, and developed our
extrapolation code so that this code can be used to calculate non-linear force
free field in heliospheric coordinate system.
To
generate vector magnetic field synoptic charts, we firstly calculate potential
field from synoptic charts. So, we obtain potential field in the photosphere.
Secondly,
we remap the photospheric vector magnetograms taken by the magnetographs.
Generally such observations are available in active regions. Finally, we
replace those remapped vector magnetograms to the potential field synoptic
chart. We use Gaussian function to smooth the vector magnetic field synoptic
chart in order to reduce the 'seam' effect (see attached figures).

Figure 7
- left panels -- the
potential field synoptic chart; right panels -- the vector magnetic field synoptic
chart.
The
extrapolation code based on Boundary Element Method has been developed to be
able to calculate non-linear force free field in the heliospheric coordinate
system. Thus the global non-linear force free field can be reproduced from the
vector magnetic field synoptic chart. We have calculated the potential field
using this code, and will compare it with other methods.

Figure 8
- top panel-- the vector
magnetic field synoptic chart; low panel-- the potential field synoptic chart
UCSD
Contributions - Report received from Bernard V. Jackson
During
these months of the MURI project Tamsen Dunn's work has allowed an accurate
incorporation of magnetic field into our time-dependent tomographic model. With the help of the UCSD MURI Co-Is and
Todd Hoeksema and Xuepu Zhao, Tamsen has successfully incorporated the Zhao and
Hoeksema (1995) magnetic field model into our solar wind analysis for eventual
use in real-time magnetic field forecasting.
Tamsen has also included the conversion of coordinates at Earth from our
model into GSM coordinates for comparison with ACE and other data sets. These
data comparisons are now underway, and will be presented at the fall AGU (Dunn
et al., 2001). With the help of other
students we have made these magnetic field data available for viewing in
three-dimensions and will also present these visualizations at the AGU (Hick et
al., 2001).
Further
MURI work was also continued on the incorporation of a 3D MHD model into our
computer code with the help of the group at
NOAA's Space Environment Center. A version of Tom Detman's 3D MHD code
to compiles and runs here on our UCSD computers. We have explored some aspects of the way to place this program
into our time-dependent tomography.
References:
Dunn, T,
B.V. Jackson, P.P. Hick and A. Buffington, 2001, "Introduction of the CSSS magnetic field model into the UCSD
tomographic solar wind model", to the fall 2001 AGU (submitted).
Hick,
P.P., B.V. Jackson, A. Buffington and M.J. Bailey, 2001, "Visualization of remotely-sensed
heliospheric plasmas", to the fall
2001 AGU (submitted).
Zhao, X,
and Hoeksema, J.T., "Prediction of the interplanetary magnetic field
strength", J. Geophys. Res, 100, 19, 1995.
We
continued incorporation of the Paramesh package into the 3-D interplanetary
solar wind code ENLIL. The hydrodynamic part of the code was successfully
tested on various test problems. An example (interaction of shocks, origin of
new contact discontinuity, and formation of a jet due to Rayleigh-Taylor
instability) can be seen as an animated gif at this URL: http://solarmuri.ssl.berkeley.edu/~odstrcil/public/images/r468.gif . We spent some time investigating various
criteria and conditions for refinement and derefinement of the numerical grid.
The magnetic part of the code has been modified as well and its verification is
in progress; together with development of IDL procedures for visualization of
the magnetic field on block-structured data.
Odstrcil
was invited to present a talk on "Numerical Simulations of Interplanetary
Disturbances" at the SOLSPA (Solar Cycle and Space Weather) conference in
Vico Equense, Italy, September 24-29, 2001.
University
of Hawaii - received from Jeff Kuhn.
We
continue to support the on-line vector magnetic field measurements obtained
from the IVM. An intermittent electronic steering-mirror servo gain problem was
identified and tentatively solved. A replacement servo control module for the
IVM mechanisms was identified and has been procured. The filter wheel required for rapid line selection (between
photospheric and chromospheric lines) has been fabricated.
The SOLARC
instrument declination drive and clutch assembly were fabricated and installed
in the telescope in order to improve its pointing stability.
The paper
"Persistent Coronal Streamers and Identification of Sunspot Clusters"
by Jing et al. has been accepted for publication in ApJ. This paper shows how
large scale coronal streamers can be sustained by the global field contribution
from long-lived sunspot clusters.
University
of New Hampshire - received from Terry Forbes.
Terry
Forbes has been working with Dave Webb on a comparison of CME observations from
SMM and SOHO with predictions of a previously published model by Lin and Forbes
(2000) for the growth of the current sheet which forms in the aftermath of a
CME. One of the key factors which
affects how the position of the lower and upper tips of the current sheet
evolve with time is the variation of the coronal density with height. This variation affects the rate of
reconnection in the sheet, and thus, the rate at which the current sheet is
eroded by reconnection.
After comparison
of the SMM observations with the published model it has become apparent that
the exponential density model previously used is not adequate. However, by replacing the exponential
density model with a much more realistic one published by Sittler and
Guhatahkurta (1999), we have now been able to obtain as reasonable agreement as
can be expected for the Lin and Forbes model which is not really valid at large
distances (> 3 Rsolar) away from the Sun.
Two
aspects of this work which may be of interest to other team members are: (1) the Sittler and Guhatahkurta model
provides a fairly realistic density model of the inner corona while at the same
time being relatively easy to implement in a theoretical analysis. (2)
Although the Lin and Forbes model provides the essential ingredients to
account for the onset and initial propagation of CMEs it is severely limited by
being a planar, two-dimensional model.
In its present form in can only provide qualitative results, but it has
the potential to serve as a guide to the behavior expected to occur in more
realistic, three-dimensional models.

Figure 9
- This
diagram shows the emergence from the Sun of a CME/flux-rope (blue shaded
region) which drives a shock (thick red arc) into the ambient solar wind. Ions (dots) are accelerated by the process
of diffusive shock acceleration and excite hydromagnetic waves in front of the
shock (denoted by wiggles in the spiral magnetic field). The excited waves, which greatly enhance the
rate of ion acceleration, are transmitted through the shock and trap
accelerated ions downstream where they are cooled in the expanding solar
wind. At the outer extent of the
excited-wave sheath some precursor ions escape the shock by magnetic focusing
and propagate nearly scatter-free to Earth orbit (denoted by a schematic Earth
with bow shock).
References:
Lin, J.,
and T. G. Forbes, Effects of reconnection on the coronal mass
ejection
process, J. Geophys. Res., 105, 2375-2392, (2000).
Sittler,
E. C. J., and M. Guhathakurta, Semiempirical two-dimensional
magnetohydrodynamics
model of the solar corona and interplanetary medium,
Astrophys.
J., 523, 812-826, (1999).
Work Performed From October
1 2001 – December 31 2001
Progress
toward our MURI goals is described in detail in the sections as organized by sub-award institution. During the next 10 weeks, George Fisher and
Dana Longcope (member of the Solar MURI team) will be at the Institute for
Theoretical Physics in Santa Barbara, participating as ``program coordinators''
for a special program on Solar Magnetic Fields. Many other members of our team will also be participating in this
program, and our next quarterly report will describe research done at the ITP
that is supportive of our project.
UC
Berkeley Report (assembled by George
Fisher)
Fisher
organized the December 9 2001 MURI team meeting which was held at
the Space
Sciences Lab. The focus of that meeting
was the organization of several "mini-workshops" over the coming
year. The minutes of the meeting will
be posted on the "solarmuri" website separately. Briefly, the mini-workshops will address
these topics: (1) Well defined numerical experiments exploring CME eruption
mechanisms (hosted by Terry Forbes at UNH from May 14-16), (2) How to use vector
magnetogram observing sequences to drive MHD codes (hosted by George Fisher at
UCB around the 1st week of May), and (3) a workshop on contructing global
magnetic maps of the Sun, to be held in Boulder on April 15. Bernie Jackson is organizing this workshop.
Abbett and
Ledvina demonstrated the new code ZeusAMR, a merge between PARAMESH and Zeus3D,
at the Fall AGU by performing simulations of magnetic flux emergence into the
low corona. The 3D MHD code ANMHD was
used to drive the photospheric boundary with the top of a rising, moderately
twisted Omega loop, and ZeusAMR was able to refine the mesh where the bipole
emerged through the photosphere and corona, allowing the simulation box to span
a large portion of the low corona while simultaneously resolving the region of
interest.
Ledvina
has continued work with the non-AMR version of ZEUS-3D in spherical
coordinates. The current challenges in
that area are the proper description of the inner boundary conditions, and the
need for implementation of the Boris correction scheme in order to reduce the
time step size.
This
spring, Ledvina will take the lead role in developing a spherical version of
ZEUS-AMR that will be applied to the global corona.
Yan Li has
made major progress working with Dick Canfield on the MURI case studies data
collection and website. The event list is becoming quite large since different
groups are studying different types of phenomena (e.g., the Montana focus on
sigmoids, her own focus on CMEs). The progress on this can be seen at the
website
http://sprg.ssl.berkeley.edu/~yanli/muri/events.html
. Yan Li also presented a poster at the Fall AGU meeting showing the response
of global potential field models, based on a large-scale photospheric dipole
field, to Bill Abbett's model of emerging active region fields. The poster
included a first attempt to model the same event in a time-dependent global MHD
simulation, carried out by Jon Linker at SAIC, who collaborates with us through
a related NSF Space Weather project. The work shows the evolution of coronal
hole extensions in response to the active region emergence, similar to the
"Whole Sun Month" study period scenario. The helmet streamer above
the active region has the appearance of splitting when it is on the limb, as is
sometimes observed in coronagraph images. No major transient loop eruption was
produced in this preliminary study using the MHD model, but the emergence was
slow enough to allow almost quasistatic adjustment of the corona, and there was
no twist in the emerging active region fields or shear in the initial helmet
streamer belt. Future work along these lines is planned to consider the impact
of all of these factors.
Janet
Luhmann presented a Fall AGU poster focused on examining the relative locations
of helmet streamer belt and the involved active regions at times of CMEs. In
the low solar activity cases examined, the involved active regions were often
located in closed field regions outside of the main helmet streamer belt
determined from potential field source surface models. Occasionally, the active
regions lay beneath the helmet streamer belt. The interplanetary consequences
for these scenarios seem to differ, with the former producing ICMEs in low speed
wind at ACE and the latter producing ICMEs on the leading edge of high speed
streams. However, tooo few cases have been examine thus far to conclude that
this occurs as a rule. It also appears that the active region fields become
engaged in the helmet streamer belt following eruptions in the cases where they
are initially isolated. However, this interpretation is greatly limited by the
use of potential field models to describe the active region fields. Work along
these lines will continue in an effort to help define realistic CME simulation
scenarios.
We have
made an offer of a postdoctoral appointment to Brian Welsch, who is completing
his PhD in Physics at Montana State University under Prof. Dana Longcope. Welsch plans to join our group in February or
March, and will work on projects in collaboration with MURI team members and
with our solar colleagues at the Naval Research Laboratory.
BBSO
Report (sent by Yong-Jae Moon)
(1)
Visible-Light Fabry-Perot for Imaging Vector Magnetograph: After successful
testing a Queensgate ET-50 Fabry-Perot in our laboratory, we are preparing for
testing it on our 65 cm telescope. We expect camera control software to be
ready soon.
(2) Global
H-alpha Network: Now we are providing recent solar flare movies and daily full
disk movies from global H-alpha network (http://www.bbso.njit.edu/
Research/Halpha/). Their observing logs and charts are also available.
(3) Field
orientation in the interplanetary flux ropes and filaments: Using ACE
measurements of the interplanetary magnetic fields, we define the orientation
of magnetic flux ropes in magnetic clouds and compare them to the orientation
of the solar magnetic fields and disappearing filaments. We have found that the direction of the
axial field in the flux ropes and their helicity are consistent with the
direction of the axial field and helicity of the erupted filaments. Thus, the
geoeffectiveness of a CME is defined by the orientation and structure of the
erupted filament, and by its magnetic helicity, as well. We now use this
technique to forecast geoeffectiveness of CMEs using full disk H-alpha images
from the Global H-alpha Network, full disk SOHO/MDI and high resolution BBSO
DMG magnetograms (Yurchyshyn al., ApJ, in press).
(4)
Magnetic field changes associated with a X20 flare: Big Bear Solar Observatory
observed the X20 flare that occurred at approximately 21:50 UT on 2001 April 2
with its standard complement of instruments. We have studied the evolution of
high resolution and high cadence longitudinal magnetograph observations in the
region of the flare. The data reveal that there was a significant increase in
the magnetic field on the limbward side of the neutral line of the active
region at the location of the flare, while the magnetic field on the side of
the neutral line closer to the disk center remained constant (Spirock et al.
submitted to ApJ).
(5)
Relationship between magnetic helicity and flaring flux: Using a set of 6.5
hour 1 minute cadence MDI magnetograms of NOAA 8100, we have obtained the
magnetic helicity transport rate via photospheric footpoint shuffling motions. As a result, we have found a very
close correlation between the integrated X-ray fluxes of homologous flares and
the corresponding magnetic helicity accumulated during the flaring time interval. We also note an abrupt increase of photospheric
shuffling motion around the flaring
time of M4.1 flare. (Moon et al. in
preparation)
(6)
Statistical evidence of sympathetic flares We collected 48 sets of sympathetic flare candidates, a pair of
consecutive flares in which the second flare starts before the first one ends.
To separate highly probable sympathetic flares from them, we estimated the
ratio of actual flaring overlap time divided by random- coincidence time. We have found a noticeable overabundance at
short time intervals in the waiting time distribution of highly probable data,
implying that sympathetic flares really exist.
It is also noted that transequatorial loops are more intimately
associated with them than longitudinal loops are. (Moon et al. in preparation)
(7)
Publications:
Yurchyshyn
al.'s paper entitled with
"Orientation of magnetic field in the interplanetary flux ropes and solar
filaments" is accepted for the publication in the ApJ.
Moon et
al's paper entitled with
"Force-freeness of solar magnetic
fields in the photosphere" is accepted for the publication in the ApJ.
Moon et
al's paper entitled with "Flaring
time interval distribution and spatial correlation of major X-ray solar
flares" is published in the A12, 2001 issue of
JGR-space physics.
In
summary, we continued development work on our existing CME `breakout' model code, continued development
work on a High Order Godonov version, and
we filled a post-doctoral position.
We have
implemented a revision of the Boris correction, in combination with a Lorentz
factor, in an attempt to control spurious velocities associated with the
cavitation phenomenon. We are currently testing this design.
We have
begun building support for non-cartesian coordinates into the development
version of Paramesh, in preparation for its use with the high order Godonov
code under development.
We made an
offer of a post-doctoral research position to Mr. Andrew Phillips from the
University of Manchester, UK, contingent upon his successful completion of his
PhD, which he has accepted. His expected start date is early February 2002.
To choose
appropriate observational case studies for our project, it is necessary to
determine which regions are well observed, in the sense that they provide
useful constraints for numerical modeling (case studies). One of the necessary conditions is that the
region be well observed in the form of Hawaii vector magnetograms. For this purpose Canfield and MSU
undergraduate Zachary Holder completed a web page
http://solar.physics.montana.edu/muri/vec/ that documents the available Hawaii vector
magnetograms for all solar events that appear in either Yan Li's list of
interplanetary events and Bob Leamon's list of interplanetary events associated
with eruptions in sigmoids.
On
November 26th, Dr. Stephane Regnier, from the Institut d'Astrophysique Spatiale
in Orsay, France, took up a postdoctoral fellowship in the MSU solar group
immediately after successfully defending his thesis on modeling of the 3D
structure of coronal magnetic fields.
He promptly set to work to identify those regions on the lists of Li and
Leamon which are best observed from the point of view of the Hawaii
magnetograms, using the information gathered by Canfield and Holder.
In
November, Dr. Stephane Regnier joined the group as a Post Doctoral Research
Associate. He has begun installing the
code with which he will extrapolate vector magnetogram data.
Piet
Matens participated in Sara Martin's PROM
workshop in Sac Peak in the week of October 12, and presented my paper
on "Origin and Evolution of
Filament-Prominence Systems", as a well as a summary of the work I
did with REU student Paul Wood (St. Andrews) in the summer of 2000.
On
November first Matens gave the Astronomy research seminar at MSU, entitled
"Origin
and Evolution of Filament-Prominence Systems", very much the same content
as the PROM talk. On 20 November He presented a "classical" paper for
the Solar Journal Club, "The Topology of the Sun's Magnetic Field and the
22-Year Cycle" by H.W. Babcock (ApJ 1961), and still highly relevant to
our research.
Piet
martens worked on a model of filament formation in delta-spots, that is consistent with my
"head-to-tail" linkage idea, yet works for newly emerged flux in this delta spot as well.
OUR
Nugget: http://solar.physics.montana.edu/muri/nuggets/2001_dec.html
.
Stanford
(report received from Yang Liu)
Our
website began to provide magnetic maps of the whole Sun. We continued
development work on vector magnetic field synoptic charts and reconstruction of
global non-linear force free field, and continued the 'synoptic chart' improvement.
The
magnetic maps of the whole Sun are now available at http://soi.stanford.edu/data/farside/index.html
. The farside images are computed from MDI surface velocity data using the
seismic holography method developed by Lindsey and Braun (2000). Those farside
images can show the locations of an
accumulation of magnetic field on the
far surface. A new whole-Sun map is computed for each 12 hours.
We have
generated the synoptic magnetogram map and vector magnetic field synoptic map
of CR1968 in combination with the full
disk magnetograms taken by SOHO/MDI and vector magnetograms taken by ground-based magnetographs. We have
therefore computed the global potential field and non-linear force free field
from these maps. Comparison shows that force free field is evidently sheared
while potential field has additional magnetic connectivities between active
regions that don't show up in force free field. Observation suggests force free
field is more realistic.
Improvement
of the "synoptic chart", the monthly synoptic magnetogram maps, is
going on. We are correcting the effect
of east-west inclination of large-scale photospheric magnetic fields in order to get the "real" radial
component by using the method suggested
by Shrauner and Scherrer(1994) and further developed by Ulrich et al.(2001).
UCSD
(Report received from Bernie Jackson)
During the
last 3 months of the MURI project Tamsen Dunn's work allowed an accurate
incorporation of Zhao and Hoeksema (1995) magnetic field model into our solar wind time-dependent tomographic
model. Data comparisons were presented at the fall AGU (Dunn et al., 2001). We have made these magnetic field data available for viewing in three-dimensions
and presented these visualizations at
the AGU (Hick et al., 2001; Jackson and Hick, 2001). Tamsen has incorporated this magnetic field analysis into both
our time-dependent and corotating IPS
tomographic model. The corotating model is more stable and with higher spatial
resolution than the time-dependent
model, and thus we intend the first use of our real-time Space Weather analysis to include the
corotational technique.
Further
MURI work was also continued on how to incorporate changing magnetic fields into our computer code with
Nick Arge and the help of others in the
group at NOAA's Space Environment Center. This has involved attempts to get different observatory data
sets to accurately show daily changes
in order that we may possibly observe CMEs in global solar surface magnetic fields as changes on short time scales as
the CMEs occur. To this end we have
begun a MURI mini-workshop to be convened on April 15, 2002 at NOAA at the
beginning of Space Weather Week (April
16-19, 2002) for those interested in helping with this forecasting project.
If you are interested in attending, please contact Bernie Jackson.
In a more
recent development, we have begun a collaborative effort with Len Burlaga at
Goddard to use the time-dependent tomography to map heliospheric structures that have been observed previously by
multi-spacecraft in situ
observations. In one of the
well-studied time periods, the Helios
photometer data appear to show the presence of a density enhancement
behind a shock front in the inner
heliosphere. Although these shock
fronts have been observed in white-light before (Jackson, 1986), images of them from the tomography are a first.
References:
Dunn, T,
B.V. Jackson, P.P. Hick and A. Buffington, 2001, "Introduction of the CSSS
magnetic field model into the UCSD tomographic solar wind model", to the
fall 2001 AGU.
Hick,
P.P., B.V. Jackson, A. Buffington and M.J. Bailey, 2001, "Visualization of
remotely-sensed heliospheric plasmas", to the fall 2001 AGU.
Jackson,
B.V, 1986, "Brightness observations of the density enhancements behind
shock waves using the Helios spacecraft photometers", Advances in Space
Res., 9, 69.
Jackson,
B.V and P.P. Hick, 2001, "A study of interacting plasma phenomena using
the tomographic 3-dimensional reconstruction techniques developed for the Solar
Mass Ejection Imager", to the fall 2001 AGU.
Zhao, X,
and Hoeksema, J.T., "Prediction of the interplanetary magnetic field
strength", J. Geophys. Res, 100, 19, 1995.
Colorado/CIRES (Report received from Dusan Odstrcil)
Three
different computational studies were realized by the numerical code ENLIL and
results were presented at the Fall AGU 2001 Meeting.
In the
first study, 3-D heliospheric computations were driven by the empirical model
of the ambient solar wind for 12 Carrington rotations in 1995. This study was
realized with Nick Arge from NOAA/SEC, and its aim is to develop more realistic
model of the ambient background solar wind. Many large-scale structures match
observations quite well, however, improvements are necessary for fast flows
from coronal holes at high latitudes as well as detail structures of the slow streamer
belt.
In the second study, the near-Earth solar
wind was driven by WIND observations for May 14-18, 1996 events when IMP-8 and
INTERBALL spacecrafts were upstream the magnetosphere. This study was realized
with Chuck Goodrich from University of Maryland, and its aim is to determine
how many spacecrafts at L1-halo orbit are adequate for reliable and accurate
forecasting of solar wind parameters hitting the magnetosphere. Though, during
studied time period, the WIND was closer to Earth than to the L1-point and
solar wind did not involved large variations in speed; simulations showed
difficulties in using single-spacecraft observations. Work is in progress to
use other, probably more suitable, events.
In the
third study, a hypothetic 2-D scenario of interacting magnetic flux ropes was
considered. This study was realized with Marek Vandas from Astronomical
Institute Ondrejov and Peter MacNeice from Drexel University, and its aim is to
provide first insight into interacting CMEs, reported recently as cannibalistic
CMEs. Numerical simulations have shown (a) distortion of a shock passing
through flux rope, (b) amplification of the shock strength, (c) gradual
coalescence of flux ropes, and (d) origin of plasmoids due to tearing
instability. These effects strongly depend on specific plasma conditions, and
work is in progress to investigate dynamic phenomena under various
"typical" conditions. Using the Paramesh is particularly effective
for this problem, because of fine resolution of shock interaction, reducing numerical
diffusion at magnetic reconnection, and reducing computational demands.
Presentations
C.N. Arge, D. Odstrcil, and V.J. Pizzo, A simple modular Sun-to-Earth propagation
model: Verification of model predictions,
Fall AGU Meeting, San Francisco, CA, December 10-14, 2001.
D. Odstrcil, V.J. Pizzo, C.C. Goodrich, and
P.J. MacNeice, Simulation of
small-scale solar wind structures upstream of the Earth, Fall AGU Meeting, San
Francisco, CA, December 10-14, 2001.
V.J. Pizzo
and D. Odstrcil, Global simulations of propagating CMEs, Fall AGU Meeting, San
Francisco, CA, December 10-14, 2001.
Mees
synoptic data continues to be obtained in conjunction with the Hessi targets
defined by the Max Millennium Chief Observer.
IVM magnetograms have been obtained for all active regions and rapid
cadence magnetograms of Max Millennium selected regions are being archived.
MCCD-H-alpha imaging spectroscopy of Max Millennium targets have also been
obtained. Mees data will soon be archived to DVD media.
Hardware
modifications to the IVM have been completed. A filter wheel for Na and Fe-line
magnetograms is installed and awaits software integration into the observing
system.
The clutch
assembly for the SOLARC declination drive was tested and removed -- we
anticipate installing a tangent arm assembly to stiffen the declination
pointing. The prime focus heat dump and occulting assembly has been designed
and optical baffling assemblies are currently being fabricated in the mechanical
shops.
The IR
camera and fiber spectrograph has been operated in the Waiakoa laboratory but
currently is waiting for a repaired vacuum pump.
Jing Li is
extending her study of persistent coronal streamers (ApJ, 2002, Feb. 1) to see
if photospheric magnetograms can be used to predict and understand the large
scale coronal structure. Li will also combine this study with CME data to look
for statistical clues to the triggering mechanisms for CMEs.
M.A. Lee
gave a presentation at the Dec. 9th 2001 Team Meeting prepared by T.G.
Forbes. The presentation included a
proposed configuration for the onset of CMEs which could be tested using a
global 3D MHD model. The proposed
configuration is a generalization of a configuration published in 1999 by S.
Titov and P. Demoulin (1999), and it is shown in the attached figure. The configuration is based on previous work
by many authors (e.g. van Ballegooijen and Martens 1989 and Lin et al. 1998)
and is closely related to configurations proposed by Low (1994), Amari et al.
(2000), and Sturrock et al. (2001), among others.

Figure 10
- Field sources for an
idealized configuration which has been proposed by Titov and Demoulin to
explain the onset of CMEs. The field is
comprised of three different sources:
(1) a flux rope, (2) an imaginary circular line current at depth, d,
below the surface, and (3) positive and negative imaginary magnetic charges
(monopoles) also at depth d below the surface.
It has been conjectured that the field will lose equilibrium or
stability when the large radius, R, of the flux rope exceeds the square root of
two times the distance, L, between the two charges.
The MURI
contingent at the University of New Hampshire will host a three-day workshop
devoted to the topic of CME initiation will at the Durham campus of the
University of New Hampshire from May 14 to 16, 2002. Participation will be by
invitation only but will include Navy, Air Force, and other non-university
participants. The principal goal of the
workshop is to come up with a series of magnetic field configurations which can
be used to test various proposals for the onset of CMEs based on either
ideal-MHD, or resistive-MHD mechanisms.
Cited
References:
Amari, T.,
J. F. Luciani, Z. Mikic, and J. Linker, A twisted flux rope
model for
coronal mass ejections and two-ribbon flares, Astrophys. J.,
529,
L49-L52, 2000.
Lin, J.,
T. G. Forbes, P. A. Isenberg, and P. Demoulin, The energetics of
flux-rope
prominence models in axially symmetric systems, New Perspectives
on Solar
Prominences, IAU Colloquium 167, 150, 350-353, 1998.
Low, B.
C., Magnetohydrodynamic processes in the solar corona: Flares,
coronal
mass ejections, and magnetic helicity, Plasma Phys., 1, 1684-1690,
1994.
Sturrock,
P. A., M. Weber, M. S. Wheatland, and R. Wolfson, Metastable
magnetic
configurations and their significance for solar eruptive events,
Astrophys.
J., 548, 492-496, 2001.
Titov, V.
S., and P. Demoulin, Basic topology of twisted magnetic
configurations
in solar flares, Astron. Astrophys., 351, 701-720, 1999.
van
Ballegooijen, A. A., and P. C. H. Martens, Formation and eruption of
solar
prominences, Astrophys. J., 343, 971-984, 1989.
Work Performed Jan 1 2002 – March 30 2002
ITP program
on solar magnetism
Solar MURI
team members Fisher and Longcope were the coordinators of a program at the
Institute for Theoretical Physics at UCSB entitled "Solar Magnetism and
Related Astrophysics", which took place between January 14 and March 29 of
2002. The program was attended by solar physicists and other astrophysicists
from many parts of the world, and included several other Solar MURI team
members (e.g. Abbett, Forbes, Goode,
Ledvina, Luhmann, Lundquist & Wang) and a number of our Associate team
members (e.g. Fan, Gibson, & Metcalf).
To kickoff our program, we organized a conference entitled
“Observational Challenges for the next Decade of Solar Magnetohydrodynamics”
which took place January 16-18. The schedule of talks, and the slides and
actual audio/video of the talks at this conference can be viewed or downloaded
from http://online.itp.ucsb.edu/online/solar02/si-conf-schedule.html .
A significant part of the conference was devoted to observations of
eruptive flares and CMEs.
The
scientific topics addressed by program members ranged from the origin of
magnetic fields in the solar interior to the structure of the outer
corona. During most of the 11 weeks of
the program, we had roughly 3 talks per week.
The slides of these talks, as well as the audio/video of these talks,
can be viewed or downloaded from http://online.itp.ucsb.edu/online/solar02/ .
The talks are a representative sample of the work that was done during
the program.
We are
grateful that the ITP decided to fund a program in Solar Physics at this time,
and honored to play a major role in coordinating the program. The Solar MURI project benefited greatly
because of collaborative research that occurred on several problems of interest
to the project.
Two new postdocs were hired with MURI funding, including Andrew Phillips (Drexel University) and Brian Welsch (UC Berkeley).
Congratulations to MURI team members from UH and BBSO for their successful DURIP proposal to AFOSR! This DURIP proposal will greatly improve observing facilities on Haleakala and at BBSO that support our Solar MURI observational research.
Planning for at least 3 MURI mini-workshops has taken place over the past 3 months. Bernie Jackson is sponsoring a workshop on synoptic-scale magnetogram data on April 15 in Boulder; Fisher and Canfield are sponsoring a workshop April 29-May 1 at Berkeley on the use of vector magnetogram data in numerical simulation, and Forbes is hosting a workshop May 14-16 in Durham NH on magnetic configurations that lead to eruptive phenomena. If you are interested in attending one of these workshops contact Bernie Jackson, George Fisher, or Terry Forbes, respectively.
The next Solar MURI team meeting will take place at the SPD/AAS meeting in Albuquerque, most likely Sunday June 2. The date will be finalized in the near future.
Following are the reports from the individual institutions:
Brian Welsch, a recent Physics graduate of Montana State University, was hired as our “Solar MURI postdoc”. Brian will collaborate with various members of our team and with our Associate team members at NRL in Washington. Brian started work as of March 1, 2002.
Fisher spent most of his effort in the past 3 months as a program coodinator for the ITP program on Solar Magnetism, along with Dana Longcope. He and Canfield hashed together the agenda for the MURI mini-workshop on using vector magnetograms in MHD modeling of the solar atmosphere.
Abbett and Associate team member Yuhong Fan from HAO have succesfully merged Fan's version of ZEUS-3D into the ZeusAMR code. One of the many improvements of this updated version is that the Zeus-3D transport step is no longer directionally split; thus, far fewer inter-block communications are necessary in a given time step, making the AMR code more efficient. Abbett has begun work on using MacNeice's PARAMESH framework as a "code-coupling" tool to merge subsurface simulations of active region flux emergence to the ZeusAMR model corona.
Ledvina has continued work on the develop a steady-state global MHD coronal model using the Zeus-3D code. He has added the Boris correction/
Alfven limiter to Zeus-3D. Standard MHD does not restrict the propagation speed of Alfven waves. Plasma conditions near the base of the corona can result in unphysically high Alfven speeds. Boris (1970) included the displacement current in his re-derivation of the MHD equation. This resulted restricting the propagation speed of the Alfven waves to the speed of light. Boris then suggested that the speed of light could artificially be lowered allowing an explicit calculation to take larger time steps. This has resulted in a factor of five increase in the speed of our simulation runs. Ledvina has also experimented with different ways of treating the subsonic subAlfvenic lower coronal boundary. Together with Abbett he has begun work on using MacNeice's PARAMESH as a frame work for coupling different simulations. He has carried out a few proof of concept experiments and examined some of the dangers of miss-matched physics at code interfaces.
Janet Luhmann participated in the solar magnetism Institute for Theoretical Physics Workshop convened by Longcope & Fisher at UCSB, where she presented a seminar on "The large scale coronal context of CMEs". Other aspects of this work were also described in a poster presented at the First STEREO Science Workshop in Paris.
A collaboration between Yan Li, Luhmann, and Stanford MURI CoIs, is slowly converging on a picture that rules out large-scale photospheric field changes as an underlying cause of CMEs. Rather, it is pointing to the interaction of nonpotential active regions with the helmet streamers as the underlying process. They are examining several periods where the relative locations of the helmet streamer belt and active regions can initially be analyzed with a potential field source surface model. Yang Liu at Stanford is applying vector magnetograms and nonlinear force free global modeling to one of these periods. The aim is to reconstruct scenarios for the interactions of active region and helmet streamer fields that can be tested with the MHD models under development by Steve Ledvina and Bill Abbett. Luhmann and Ledvina will also be giving invited presentations at the upcoming CCMC workshop in Maryland. Yan Li will be attending the MURI Magnetogram Synoptic Map workshop organized by Bernie Jackson at Space Weather Week.
Global H-alpha Network:
Major progress is as follows.
Active Region Monitor (ARM):
We have updated the ARM with the following changes:
Rapid Changes of Magnetic Fields Associated with Six
X-class Flares:
We found significant changes in the photospheric magnetic fields associated with six X-class flares. Based on the analyses of the line-of-sight magnetograms, all six events had an increase of the magnetic flux of the leading polarity on the order of a few times 1020 Mx while each event had some degree of decrease in the magnetic flux of the following polarity. The flux changes are considered impulsive, as the “change-over" time, which we defined as the time to change from pre-flare to post-flare state, ranged from 10 to 100 minutes. The observed changes are permanent. Therefore, the changes are not due to changes in the line profile caused by flare emissions. For the three most recent events, when vector magnetograms were available, two showed an impulsive increase of the transverse field strength and magnetic shear after the flares, as well as new sunspot area in the form of penumbral structure. One of the events in this study was from the previous solar cycle. This event showed a similar increase in all components of the magnetic field, magnetic shear and sunspot area. We present three possible explanations to explain the observed changes: (1) the emergence of very inclined flux loops, (2) the changing of the magnetic field direction and (3) the expansion of the sunspot which moved some flux out of Zeeman saturation. However, we have no explanation for the polarity preference, i.e. the flux of leading polarity tends to increase while the flux of following polarity tends to decrease slightly. (Wang et al., submitted to ApJ)
A Revised Shock Time of Arrival Model for IP Propagation
(STOA-2):
We have examined a possibility for improvement of the STOA Shock Time Of Arrival) model for interplanetary shock propagation. Noting observational and numerical findings that the radial dependence of shock wave velocity depends on initial shock wave velocity, we suggest a simple modified STOA model (STOA-2) which has a linear relationship between initial coronal shock wave velocity and its deceleration exponent. Our results show that the STOA-2 model not only removes a systematic dependence of the transit time difference predicted by the previous STOA model on initial shock velocity, but also reduces the number of events with large transit time differences.(Moon et al., Geophys. Res. Let., in press)
A statistical study of two classes of CMEs:
We made a comprehensive statistical study to address the question whether two classes of coronal mass ejections (CMEs) exist. We have analyzed 3217 CME events observed by SOHO/LASCO in 1996 to 2000, which are compiled in the CME catalogue by Yashiro \& Michalek. We have examined the distributions of CMEs according respectively to speed and to acceleration and investigate the correlation between speed and acceleration of CMEs. The same statistical analysis is conducted not only for the whole CME data set, but also for two subsets containing those CMEs that show a temporal and spatial association either with GOES X-ray solar flares or with eruptive filaments. The eruptive filaments data were collected from NGDC and BBSO. The fraction of flare-associated CMEs increases with the CME speed, whereas the fraction of eruptive-filament-associated CMEs decreases with the CME speed. This result supports the concept of two CME classes. We also found evidence for two components in the CME speed distribution in the CME data associated with flares larger than M1 class and in the CME data related with limb flares. Our results suggest that the apparent single-peak distribution of CME speed can be attributed to the projection effect and possibly to abundance of small flares too.
We also note that there is a likely correlation between the speed of CMEs and associated limb flare's X-ray flux integrated over the flaring time. (Moon et al., in preparation)
Publications:
Wang et al's paper entitled with "Core and large-scale structure of 2000 November 24 X-class Flare and CME" is accepted for the publication in theApJ.
Moon et al's paper entitled with "Statistical evidence for sympathetic flares" is accepted for the publication in the ApJ.
Moon et al's paper entitled with "Flare activity and magnetic helicity injection by photospheric horizontal motions" is accepted for the publication in the ApJ.
Moon et al's paper entitled with "A revised shock time of arrival (STOA) model for interplanetary shock propagation" is accepted for the publication in the Geophys. Res. Letter.
Shakhovskaya et al.'s paper entitled with "Limb Prominence Eruption on
11 August 2000, as Seen from Ground- and Space-Based Observations" is accepted for the publication in the Solar Physics.
Spirock et al's paper entitled with "Rapid changes in the longitudinal magnetic field related with the 2001 April 2 X20 flare" is accepted for the publication in the ApJL.
Drexel (received from Peter MacNeice)
We continued development work on our existing CME `breakout' model code, continued development work on a High Order Godunov version, and completed development work on version 3.0 of the Paramesh AMR package.
We tested a revision of the Boris correction, in combination with a Lorentz factor, in an attempt to control spurious velocities associated with the cavitation phenomenon, which appear in higher resolution runs. This fix and all of the other fixes we have attempted to date have introduced other failure modes. We are exploring the role which the FCT and AMR play in the evolution of all these failure modes. Mr. Gao continued development of a high latitude, low resolution version of the same `breakout' calculation.
We completed the coding of support for non-cartesian coordinates in the development version of Paramesh, in preparation for its use with the high order Godonov code under development. Testing is now in progress. This functionality will also be used by the Berkeley and NCAR codes.
Dr. Andrew Phillips, a new postdoc, began work on the project in mid February. He has been developing a Sedov test of the hydrodynamics of the High Order Godunov code that is under development.
Montana State University (received from D. Longcope)
During this period a key milestone was achieved -- the selection of NOAA
8210 for the first of what may be several case studies of an eruption from the Sun observed from the photosphere to interplanetary space. The reader is referred to the MSU MURI nugget written on this subject: http://solar.physics.montana.edu/muri/nuggets/2002_mar.html .
While Longcope was in Santa Barbara, leading the workshop at the
Institute for Theoretical Physics (UCSB), Canfield acted as MSU PI. The main work was preparation for Hawaii Imaging Vector Magnetograph (IVM) data reduction and 3D numerical modeling. We purchased and installed an Exabyte Mammoth tape drive to read IVM data tapes sent by Labonte from JHU/APL. We determined empirically that the MSU-UH Internet-2 connection is adequate for transfer of future IVM data from Hawaii. We took advantage of a two-for-one matching offer from Sun Microsystems and ordered two Sun Fire V880 workstations for the price of one. One will be used for MURI IVM data reduction and one for MURI modeling. We expect that we will be able to reduce about four IVM magnetograms per day, which will allow us to fully take advantage of the over-100 magnetograms we have for NOAA 8210 before, during, and after its May 1, 1998 ~2240 UT eruption.
Canfield gave a public talk "Sunspots, Galileo, and You" to over 400 students representing 82 schools in southeastern Montana in a regional science fair -- Science Expo 2002 -- on March 22 in Billings, MT: http://www.billingsclinic.com/Research/ScienceExpo.htm .
Finally, Canfield collaborated with Regnier and LaBonte to achieve a capability to reduce IVM magnetograms at MSU.
Stephane Regnier worked with R. Canfield, Y. Li and Y. Liu on the selection of a good active region as MURI case study. The active region NOAA 8210 has been the selected flaring region associated with interplanetary events. The large number of magnetic data related to these events will allow us to study the evolution of the coronal magnetic field and the interplanetary field.
Stephane Regnier worked with the advices of B. Labonte on the reduction of IVM (MSO) data of the chosen active region.
Yang Liu and Stephane Regnier performed a successful comparison of 3D coronal magnetic fields reconstructed using two different methods.
Piet Martens presented a paper entitled "The Origin of Prominences and Their Hemispheric Preferences for Chirality and the Skew of Overlying Loops" at then Yohkoh 10th Anniversary Meeting "Multi- Wavelength Observations of Coronal Structure and Dynamics", in January in Hawaii. A paper with the same title has been submitted for the proceedings. The paper demonstrates that the SXT observed skew of soft X-ray arcades connected to prominences is consistent with the Martens-Zwaan model for the origin of prominences.
His proposal to the M.J. Murdock Foundation entitled "Correlation Between Solar Prominences and Sigmoids" was accepted. It will allow a local High School teacher to work with him and Alex Pevtsov to develop a visual on-line sigmoid-prominence catalog for the duration of the Yohkoh mission, an activity clearly relevant to our MURI effort.
Piet also contributed significantly w.r.t. filaments, their eruptions, and flares.
Piet worked further on his model for prominence formation in emerging delta-spots, the results of which will be submitted to ApJ later this year.
While at the Institute for Theoretical Physics in Santa Barbara, Longcope collaborated with Terry Forbes and Leon Golub to analyze observations of a flare on March 17, 2001 in NOAA 8906. This was a two-ribbon flare whose ribbons seems to extend into single contiguous ring. TRACE images revealed post-flare loops suggestive of a magnetic separatrix extending from what appeared to be a coronal null point. Longcope further refined his magnetic topology tools, and used them to identify the magnetic separatrix. MDI magnetograms were used to identify magnetic sources with active region NOAA 8906. From these it is possible to identify separatrices in linear force-free fields.
No value of alpha leads to a coronal null point. There was, however, a separatrix surface roughly outlining the chromospheric ribbons. A summary of this analysis is located at http://solarmuri.ssl.berkeley.edu/~dana/public/data/ar8906/flare.html .
Stanford University (received from Y. Liu)
In the first three months of this year, we employed a 2-D MHD code to study
CME properties, and we also compared various methods of reconstruction of 3-D magnetic field based on observation.
Liu W. is using a 2-D MHD code to study the effects of topology on CME kinematic properties motivated by a new qualitative theory proposed by Low and Zhang (2002). In that theory, fast or slow CMEs result from initial states with magnetic configurations characterized by the normal or inverse quiescent prominences, respectively. The preliminary numerical results show that the distinct topologies indeed lead to fast and slow initial speeds of CMEs, which supports the theory.
We continue our work on comparison of 3-D magnetic field structure computed from observational data based on various models and techniques. It has been shown that the calculation from vector magnetic field at the surface is the best match to the observation. We expect further models, especially MHD simulation, to examine methods and to understand coronal structure. This work can be found at http://soi.Stanford.EDU/~yliu/fieldcomp/fieldcomp.html .
References:
Burlaga, L. et al., J. Geophysical Res., 85, 2227, 1980.
Dunn, T, B.V. Jackson, P.P. Hick
and A. Buffington, “Introduction of the CSSS magnetic field model into the UCSD
tomographic solar wind model”, the fall
AGU, 2001.
Jackson, B.V, and P.P. Hick, “Time-Dependent Tomography Of
Heliospheric Features Using Global Thomson-Scattering Data From the Helios
Spacecraft Photometers During Times of Solar Maximum”, the fall AGU, 2001.
Jackson, B.V. and P.P. Hick, “A Study of Plasma Phenomena
Using the Tomographic 3-Dimensional Reconstruction Techniques Developed for the
Solar Mass Ejection Imager (SMEI)”, The First STEREO Workshop, Paris, France,
18-20 March, 2002.
Zhao, X, and Hoeksema, J.T., “Prediction of the interplanetary magnetic field strength”, J. Geophys. Res, 100, 19, 1995.
University of Colorado (Received from Dusan Odstrcil)
We have learned the TECPLOT software package for visualization of 2-D and 3-D data sets (including numerical results on adaptive meshes). This enables us to investigate 3-D topology of magnetic field during propagation of interplanetary CMEs. Further, we have developed IDL procedures for producing line-of-sight images of white light scattering from the simulated density structures. Finally, in view of recent papers on accurate solution of magnetic field on adaptive meshes, we have initiated modification of the ENLIL code for using of staggered grid, and performed the first verification tests.
Presentations:
D. Odstrcil, V. Pizzo, J. Linker, Z. Mikic, R. Lionello, P. Riley, and J. Luhmann, Comparison of CME models with observations, Invited talk, First STEREO workshop: The 3-D Sun and Inner Heliosphere, Paris, France, March 18-20,2002.
University of Hawaii (received from Jeff Kuhn)
Mees synoptic IVM data are now being archived to DVD (starting Oct. 23, 2001). Data distribution is significantly more efficient. Jing Li now has responsibility for overseeing the data distribution and for the IVM analysis. The overall data archive is accessible at http://www.solar.ifa.hawaii.edu/Reference/IVM/survey_tape_logs/ (tapes) and the new DVD logs can be found at http://www.solar.ifa.hawaii.edu/Reference/IVM/dvdlogs/ . In order to accelerate the analysis of vector field data we have planned for and ordered a faster computer that will be dedicated to daily IVM analysis and distribution. External data users will have the ability to access and analyze vector magnetic field data using this system.
The SOLARC spectrograph optical bench is now in place on the summit and the grating and optics are ordered. The upper shroud for the SOLARC secondary optics has been installed. A new declination drive and an X-Y stage for the M2 mirror assembly have been fabricated. Data on the light scattering properties of the off-axis design were collected and analyzed along with planetary imagery demonstrating the optical performance of the telescope. These results were presented in a report --The Circumstellar Imaging Telescope: Concepts for a High Dynamic Range Imaging Telescope.
Jing Li and collaborators continue investigations of coronal streamers.
Between SXT and LASCO heights there are significant differences in the streamers that can be attributed to changes from closed to open field lines. She is developing a plausible streamer model to simulate the measurements. Related work is published in Li et al. "Large-scale, Long-lived Coronal Structures Detected in Limb Synoptic Maps" in the Yohkoh 10 Proceedings.
Planning for the IR camera and spectrograph began with the unofficial announcement that hardware DURIP funds would likely be available for this activity. An active collaboration with BBSO to develop the IR instrumentation has been initiated involving Lin and Kuhn (IfA) and Goode and Denker (BBSO).
A Powerpoint summary of these and other results was generated for Col. Bellaire and is available from the IfA web site.
University of New Hampshire (received from Terry Forbes)
Progress on Solar Energetic Particle Predictions:
Work has continued on perfecting a new theory for solar energetic particles (SEPs) which treats the acceleration of particles near the shock and their transport through space self-consistently. Unlike previous theories, the new one does not have an arbitrary free-escape boundary where the standard Parker acceleration equations and the free-streaming transport equations are patched together. Consequently, it is now possible to make reasonable predictions at one AU (i.e. Earth) about the details of the energy spectrum and abundances of the energy particles. For example the reason for the existence of a free-streaming plateau prior to the arrival of the shock, an effect which was pointed out by Reames (1990), can now be understood in quantitative terms.
The new theory provides a relatively easy method for obtaining SEP predictions for various ion species from large scale MHD simulations. These predictions are made by imputing the compression ratio and the orientation of the magnetic field at each point on the CME shock and then applying the algebraic formulas of the new theory along the field lines mapping to these points. No additional level of numerical simulation is required to make these predictions, but it would be useful to test the assumptions of the theory by carrying out numerical particle simulations.
During the next quarter Marty Lee should complete his extensive manuscript in which the new theory is laid out and submit it to the Astrophysical Journal. The manuscript is complete, except for a section which discusses the errors introduced by the various approximations that the theory uses and a section on the effect of wave-wave mode coupling (i.e. turbulence) in the shock acceleration region has on the sharp roll-off of the particle fluxes at high energy.
Preparations continue for the Mini-Workshop on CME Initiation to be held May 14-16, 2002 at Morse Hall on the UNH campus in Durham, New Hampshire. The confirmed participants are:
Terry Forbes (UNH)
Marty Lee (UNH)
George Fisher (Berkeley)
Bill Abbett (Berkeley)
Brian Welsch (Berkeley)
Tamas Gombosi (Michigan)
Chip Manchester (Michigan)
Ilya Roussev (Michigan)
Dana Longcope (Montana)
Piet Martens (Montana)
Sarah Gibson (HAO)
Spiro Antiochos (NRL)
Rick DeVore (NRL)
Dave Webb (AFGL)
Ed Cliver (AFGL)
The goal of this workshop is to provide initial conditions that can be used to test proposed mechanisms for the onset of Coronal Mass Ejections.
Reference:
Reames, D. V., Acceleration of energetic particles by shock waves from large solar flares, Astrophys. J., 358, L63-L67, 1990.
During the April-June period, there were a number of developments that greatly sharpened the focus of our team, as a result of 3 workshops that were hosted by several of our team members.
First, Bernie Jackson (UCSD) organized a one-day workshop on
the topic of standardizing the generation of magnetic field maps made from
synoptic magnetogram data, in such a way that the format of the map would be
independent of the magnetogram data source.
These maps are the essential input to a number of coronal source-surface
models, and will eventually form the basis by which background MHD models of the
solar wind are generated. The conclusion of that workshop was to endorse a plan
by Nick Arge of CIRES to carry out the magnetic map standardization. This workshop was attended by members of our
MURI team, the Michigan MURI team, and several other interested members of the
community. A summary of the
recommendations can be viewed on the Solar MURI website in the directory http://solarmuri.ssl.berkeley.edu/~fisher/public/presentations/synoptic/
.
Fisher and Canfield then organized a 2 1/2 day workshop held
at SSL with the objective of understanding how to use time dependent vector
magnetogram data, measured at the photosphere, to drive time dependent MHD
simulations of the corona. One of the
main stumbling blocks is deriving a velocity field at the photosphere that is
physically consistent with the evolving magnetic field there, and one which
correctly incorporates flux emergence as well as horizontal flows. During the workshop we decided to focus on 2
well-observed eruptive events: The May
1 1998 eruptions from AR-8210, and the May 12 1997 event from a very simple
decaying active region. This workshop
was attended by members of our team, plus outside experts on the use of vector
magnetograms in theoretical models such as Zoran Mikic of SAIC, and vector
magnetograph experts Tom Metcalf of Lockheed and KD Leka of CORA. Mike Heinemann of AFRL also attended the
workshop. An agenda of the
meeting can be downloaded from the Solar MURI website in the directory http://solarmuri.ssl.berkeley.edu/~fisher/public/presentations/vmgram-workshop-2002/
. The “Plan of Action” that resulted is
also available from that same directory.
Immediately after the workshop, Dana Longcope made substantial headway
into solving the velocity problem described above. More details are described in the Montana State University
Contribution below in this report.
Terry Forbes hosted and organized a workshop to define numerical experiments on CME initiation mechanisms. The result of that workshop was a description of 3 classes of eruption models, including the evolution (shear and/or reconnection) of a single emerged bipole; the emergence of new, highly twisted magnetic flux ropes from below the photosphere; and the evolution of multi-polar configurations in which reconnection between different flux systems provides the catalyst for eruption. A summary of the 3 classes of proposed numerical experiment can be obtained from the solar MURI website under the directory http://solarmuri.ssl.berkeley.edu/~fisher/public/presentations/numerical-experiments-workshop-2002/ .
A Solar MURI Team Meeting was held June 2 in Albuquerque at the AAS/SPD meeting to inform the team members and other interested members of the community of the results of these workshops.
Below are now the individual reports from each of our constituent team institutions.
Report
from UC Berkeley: (assembled by George Fisher)
Fisher
presented an invited talk describing work that has been done on the MURI
project during the first year of funding at Space Weather week in Boulder,
April 16-19.
Fisher and
Canfield (MSU) organized the MURI mini-workshop on the use of vector
magnetogram data that was held in Berkeley April 29-May 1 to outline strategies
for using time dependent sequences of vector magnetograms to drive MHD
simulations of the corona, geared towards understanding the dynamics leading to
CME initiation.
Fisher,
Abbett, Luhmann & Welsch attended the MURI mini-workshop at UNH on
“Numerical Experiments’’ that are designed to organized by Terry Forbes. The outcome of that workshop was a
definition of 3 classes of numerical experiment that are the most urgent for
understanding the basic physics of CME initiation.
Fisher
organized the summer Solar MURI team meeting held the day before the SPD/AAS
meeting in Albuquerque, Sunday June 2nd. The primary purpose of the team meeting was to inform all the
team members the results of the workshops, and to facilitate collaboration
between team members.
To ease
the storage problem for data resulting from large scale simulations for the
Solar MURI project, as well as other related projects, Fisher purchased and set
up a dual RAID system running on a Linux box.
The RAID system uses all IDE disks, making the system far cheaper than SCSI
RAID systems. The cost for 2 TB of
on-line disk storage was $10K. This
storage is available to all the other computers in the UCB Solar MURI group via
NFS and Samba network access.
Abbett and
Ledvina are currently working on the implementation of spherical coordinates
into ZeusAMR, and will be working with Dusan Odstrcil for two weeks (at
Berkeley) at the end of July to develop the framework necessary to couple
ZeusAMR to ENLIL. Abbett and Fisher have submitted a paper to the ApJ entitled:
"A Coupled Model for the Emergence of Active Region Magnetic Flux into the
Solar Corona". This paper
summarizes the effort to drive a simple Zeus3D model corona with a subsurface
calculation performed by ANMHD. A pre-print
is available to team members in Abbett's "manuscripts" directory on
the solarmuri website.
At the end
of June, a small miniworkshop was held at Berkeley, where Abbett, Bercik,
Ledvina, Li, and Fisher worked with Yuhong Fan, and Sarah Gibson (associate
members of the MURI team from HAO) on resolving specific issues of
self-consistently driving models of the corona (with a prescribed initial field
configuration) with simulated data from
sub-surface flux emergence calculations.
These types of simulations are critical for investigating the CME
initiation process, and the types of boundary issues discussed at this
miniworkshop are directly relevant to the numerical experiments that were
proposed at the New Hamshire workshop hosted by Forbes and Lee.
Two other
publications have been recently submitted:
Fan, Abbett, Fisher : "The Dynamic Evolution of Twisted Magnetic
Flux Tubes in a 3D Convecting Flow I: Uniformly Buoyant Tubes" (submitted
to ApJ), and Ledvina, Luhmann, and
Abbett: "A Magnetohydrodynamic Test of the Wang-Sheeley Model" (submitted to ASP).
After
returning from the Institute for Theoretical Physics, Dr. Welsch spent the month of April running Monte Carlo
simulations to test the stability of coronal holes predicted by
Dr.
Luhmann's potential field source surface (PFSS) code to perturbations in the
surface magnetic field. In May, he
attended the MURI numerical experiment definition meeting at UNH -
Manchester. He then travelled to
Washington, DC, for two weeks to establish the bureaucratic framework necessary
to begin collaboration with Naval Research Lab (NRL) researchers Drs.
Antiochos, Linton, and DeVore. While
Dr. Welsch was there, these researchers
agreed to undertake a simplified version of
a numerical experiment proposed at the MURI meeting in New
Hampshire: the forced collision of two
initially distinct flux systems in a coronal MHD code, with the ultimate goal
of creating a
prominence-like
configuration with realistic driving on the lower boundary (see figure 1).
It is thought that fields possessing the correct sign of magnetic
helicity should lead to a prominence-like topology, while fields with the
incorrect sign will not.
Efforts
are now underway to begin the simulations; preliminary results should be ready
for presentation to the community at the AGU meeting in December.
Graduate
Student Loraine Lundquist has tentatively settled on a dissertation topic
related to re-constructing a 3D temperature and density map of the solar
corona, using potential field models, simple solutions for coronal loop energy
equations, and a series of postulated coronal heating mechanisms. The resulting coronal configurations can
then be compared with the large existing database of coronal observations of
active regions to test the viability of various proposed coronal heating
mechanisms.

Figure 11.
In the proposed collaboration with NRL, the initial state a) consists of two bipoles which do
not share flux. After applying the
differential-rotation-like shear profile illustrated by the dotted velocity
vectors in panel a), the boundary condition will appear as that in panels b),
c), and d). In the absence of
reconnection, the topology would be that of the solid arrows in panel b). As
the numerical code is dissipative, reconnection will occur, yielding either the
prominence-like topology in panel c), or the alternate topology in panel
d). It is thought that fields
containing the correct sign of magnetic helicity will lead to the topology in
panel c).
Janet
Luhmann and Yan Li continue to work on defining the coronal settings for CME
case studies, with the goal of providing realistic boundary conditions for
simulations. Janet Luhmann spent a day at the New Hampshire CME initiation
workshop in May to represent some observational viewpoints. Luhmann (invited by
Paul Bellaire) also presented a talk on benefits of community access to models
at the CCMC special session at the Spring AGU meeting in Washington DC in May. She also attended the annual Solar
Physics Division Meeting in Albuquerque to give an invited paper in
Bernie
Jackson's special session on magnetic field
signatures of CMEs (paper title:
"Using Potential Field Models to Learn About CME Coronal Context and
Consequences"), and the Solar Wind X Conference in Pisa to present a
contribution on development of tools for solar wind source tracking (paper
title: "A Solar Wind Source Tracking Concept for Inner Heliosphere
Constellations of Spacecraft"). Both the Solar Wind X Conference paper and
the SPD paper are in the process of being written up for publication. Plans for
the summer include a visit by Dusan Odstrcil, during which he will demonstrate
how to access the output from his CME interplanetary propagation simulation.
The plan is to use these MHD results to design complementary models for solar
energetic particle acceleration and transport. Lastly, with the pending start
of the highly complementary Boston University-led NSF Science and Technology
Center: "Center for Integrated Space Weather Modeling", plans are
being discussed with George Fisher on how to take advantage of the highly
complementary nature of the MURI activity and the co-located solar and
heliospheric STC effort at UCB.
Yan Li
attened the 2002 Space weather week at NOAA/SEC in Boulder, CO, and presented a
poster paper entitled "Long term variations of the magnetic signature of ICMEs
abd their geoeffectiveness. Another project that Yan Li has been working on is
to study the interactions of the CMEs and the coronal helmet streamer belt, and
whether the different interactions are controlled by the location of the CME
source regions relative to the helmet streamer belt. This work was presented as
a poster at the 2002 AAS/SPD meeting in Albuquerque, NM. Both projects are on
going.
Yan Li
also attended the Synoptic Magnetic Map workshop held in Boulder just before
Space Weather Week, and organized by MURI team member Bernie Jackson.
Steve
Ledvina continues to develop his three dimensional MHD model of the solar
corona using ZEUS. He is currently in the
process of adding Spitzer conductivity to the model. Once it is
successfully implemented it will be incorporated into Bill Abbett's emerging
flux simulations and ZeusAMR. Steve
has successfully incorporated Alfven wave acceleration into his simulations
using a WKB approximation. He presented
a paper at both the SPD and Solar Wind X meetings that compared solar wind
speeds predicted by the empirical Wang- Sheeley relationship to wind speed
obtained by the MHD model. The results are currently being written up for
publication.
Digital Vector Magnetogram Archive Program:
Recently,
the archive programs for the digital vector magnetograph (DMG) have been
completed and incorporated into the BBSO archive package. Major changes are as
follows.
2. WWW
page of DMG Data:
A web page
is being made at the end of every day which is a summary of the DMG data for that day. It shows a IVQU set of every unique region
observed that day. This should make
searching for old DMG data in the future easier. The www page can be found in
the daily archive directory as
YYMMMDD_dmg.html.
Impulsive
Magnetic Helicity Injection:
We
investigated the impulsive injection of magnetic helicity associated with major
solar flares (three X-class flares and one M-Class flare) accompanying halo
CMEs. By analyzing four sets of 1minute
cadence full-disk magnetograms taken by SOHO/MDI, we have determined the rates
of magnetic helicity transport due to horizontal photospheric motions. We have
found that magnetic helicity of the order of $10^{41}$ Mx${^2}$ was impulsively
injected into the corona around the flaring peak time of all the flares. The impulsive helicity variations are
attributed to horizontal velocity kernels localized near the polarity inversion
lines. In all the events except one, the helicity injection increased the absolute
value of the magnetic helicity in the corona.
Another mode of magnetic helicity transport due to flux emergence and
submergence is estimated to be negligible because no significant change of
magnetic flux was observed during the flares. We found that there is a positive
correlation between the impulsively injected magnetic helicity and the X-ray
peak flux of the associated flare.
Finally, we report that there is a close spatial proximity between the
horizontal velocity kernels and Ha bright points (Moon et al. submitted to ApJ).
4.
Publications:
Gallagher
et al.'s paper entitled with "Active Region Monitoring and Flare
Forecasting" is accepted for the publication in the Solar Physics.
Wang et
al.'s paper entitled with "Rapid Changes of Magnetic Fields associated
with Six X-class Flares" is accepted for the publication in the ApJ.
Moon et
al.'s paper entitled with "Impulsive Injection of Magnetic Helicity
Associated With Major Flares" is submitted to ApJ.
Moon et
al.'s paper entitled with "A Statistical Study of Two Classes of Coronal
Mass Ejections" is submitted to ApJ.
Report
from Colorado/CIRES: sent by Dusan Odstrcil
We have
realized two different computational studies by the numerical codes ENLIL and
the results were presented at the Space Weather Week and Solar Wind 10
conferences. Both studies represent continuation in our effort to obtain more
realistic background solar wind and more accurate resolution of fine
structures.
In the
first study, 3-D MHD heliospheric computations were driven by the empirical
model of the ambient solar wind for 12 Carrington rotations in 1995. This study
was realized with Nick Arge from NOAA/SEC, and its aim is to develop more
realistic model of the ambient background solar wind. The new results (with
respect to our presentation at Fall 2001 AGU Meeting) are based on empirical
modifications of the solar wind velocities provided by Wang-Sheeley model.
Figure 12 shows the results driven by the original model (used at the NOAA/SEC
as a real-time assistance to space weather forecasters). Figure 13 shows
results driven by empirically increased flow velocities in higher latitudes. It
can be seen improved match with observations. This has encouraged work on
further sophistication of the source surface model.
In the second study, 
Figure 12
a
hypothetic 2-D scenario of interacting magnetic flux ropes was considered. This
study was realized with Marek Vandas from Astronomical Institute Ondrejov and
Peter MacNeice from Drexel University, and its aim is to provide first insight
into interacting CMEs, reported recently as cannibalistic CMEs. The new results
(with respect to our presentation at Fall 2001 AGU meeting) stems from
considering different parameters within the interacting magnetic clouds. We
found different distortions of the shock that can propagate faster (slower) in
the cloud with larger (smaller) characteristic speeds. Correspondingly, the
density behind the shock front becomes smaller (larger). We think that an enhancement
of type II radio burst, its slope change, and irregular patterns can be
associated with a localized shock strengthening and distortion.

Figure 13
Arge C.
N., Odstrcil D., Pizzo V. J., and Mayer L.,
Towards an operational Sun-to-Earth
propagation model,
Space Weather Week, Boulder, CO, April
16-19, 2002,
(poster)
Arge C.
N., Odstrcil,D., Pizzo V. J., and Mayer L.,
A simple modular Sun-to-Earth propagation
model: Verification
of model predictions,
Solar Wind 10, Pisa, Italy, June 17-21,
2002.
(poster)
Odstrcil
D., Vandas M., Pizzo V. J., and MacNeice P. J.,
Numerical simulation of interacting magnetic
flux ropes,
Solar Wind 10, Pisa, Italy, June 17-21,
2002.
(oral)
Odstrcil D.,
and Pizzo V. J.,
Numerical simulation of interplanetary
disturbances,
in Proc. SOLSPA: The Second Solar Cycle and
Space Weather
Euroconference, Vico Equense, Italy, 24-29
September 2001,
pp. 281-284, ESA SP-477, 2002.
Drexel
University Personnel: Dr.Peter
MacNeice, Dr. Andrew Phillips, Mr. Jimin Gao
In
summary, we continued development work on our existing CME `breakout' model code, continued development
work on a High Order Godunov version, and fixed some minor bugs in version 3.0 of the Paramesh AMR package.
The new
High Order Godunov code successfully modeled a spherical Sedov test explosion.
We have now implemented the initial conditions appropriate for the idealized
`breakout' model calculation. We have introduced and successfully tested a
modification to the basic algorithm to enable the initial force-free state to remain stationary, unless
perturbed.
We
developed a post-processing tool that extracts `pseudo-spacecraft' measurements
of the plasma state from the CME model results generated using the FCT
code. These are timelines of gas
properties and field strengths that a spacecraft with a specified trajectory
through the inner Heliosphere might measure. We are collaborating with a
student from the University of Michigan on analysis of these timelines and
comparison with observation.
We have
successfully tested Paramesh V3.0 on a clustered system with both Ethernet and
Myrinet interconnect, and are now working to optimize the performance of the
MPI messaging.
Report
from Hawaii: Sent by Jeff Kuhn
Mees
synoptic vector magnetic field data were obtained using the Haleakala Stokes
Polarimeter and the Imaging Vector Magnetograph during this period. H-alpha chromospheric spectroheliograms were
obtained using the MCCD. Hardware and
software changes have been implemented that place our current H-alpha
Coronagraph data on the Mees solar web site.
The SOLARC
telescope has a new roller drive declination assembly that fixes our previous
drive problems. Permanent baffling
assemblies have been installed around M2.
A Kodak CCD camera has been obtained for visible photospheric and
coronal imaging use. Sky brightness (coronal) observations have been obtained
and are being prepared for publication (SPIE, August). Preliminary design of an Ebert-Fastie long
wavelength IR spectrograph has been completed. Components are being ordered.
Don Mickey has returned to the IfA and has begun the hardware and software
integration required for the multi-spectral line upgrade for the IVM.
Li
continues to work on a sunspot cluster study covering the period 1991 to 2001.
This extends previous work on "active nest" models for persistent
solar activity. A detailed analysis of EIT, SXT and LASCO data for two CMEs has
been completed. The analysis focuses on deriving the temperature and EM of the
front, cavity and core of the developing CME. A publication of this work with
the UVCS team is under preparation.
One
objective of the Solar MURI collaboration is to develop techniques to drive
three-dimensional numerical simulations of the dynamical evolution of observed
solar active regions. One of the observational inputs for such a simulation
will be a regular sequence of vector magnetograms of the entire active region
covering an extended period. To solve
the MHD equations in the corona above
the active region it is necessary to specify an evolving velocity field at the
lower boundary, the photosphere. This velocity
field should drive the magnetic field, according to the induction equation,
along an evolution closely matching the observed magnetogram sequence.
A MURI
min-workshop was held in Berkeley to make progress toward achieving this
objective. At this workshop Longcope
presented a method using a variational technique to better define this
ill-posed problem. With inputs from
many of the workshop participants this algorithm was improved. In its present
form the algorithm will supply the velocity field connecting any pair of vector
magnetograms. Following the workshop
Longcope wrote an IDL code implementing the algorithm. During this process he worked with Isaac
Klapper (MSU) to understand the nature of singularities in the governing
equations. The existing code has been
tested using analytically-derived "magnetograms" without
perpendicular field. He has submitted a
poster to the SHINE workshop describing the algorithm.
Stephane
Regnier attended to the MURI mini-workshop on the use of vector magnetograms to
determine the coronal structures of active regions and to model eruptive
events. The numerical scheme and the results concerning a highly non-potential
active region have been presented (Regnier, Amari & Kersale, A&A, 2002,
accepted).
Dr.
Regnier worked on the IVM data reduction with the advice of K.D. Leka. Two
15-min averaged vector magnetograms have been produced in order to determine
the 3D magnetic configgurations of the active regio 8210 before and after a
series of C-class flares. The results have been presented during the
"Magnetic Coupling of the Solar Atmosphere" (EC and IAU colloquium)
in Santorini/Greece (15 minutes talk and the related proceeding).
Piet
Martens participated in the three day MURI mini-workshop at UNH, to decide on
the best setup for numerical experiments on filament and CME formation and
eruption. This was a very good meeting:
after three days of open sessions we had still interesting things to say to
each other!
The final
experiment we agreed on is a combination of Piet's own `head-to-tail' linkage model for filament
formation and Spiro's `break-out' model for filament eruption -- a complex
magnetic structure that actually looks like what one sees with MDI and EIT.
His
contribution to the Yohkoh 10 Proceedings is now on-line; it discusses relevant observational material
(the skew of X-ray arcades overlying
filaments) for numerical simulations, and models them http://solar.physics.montana.edu/martens/papers/y10.ps.gz.
During
this period Canfield helped organize and lead the MURI mini-workshop on the use
of vector magnetograms to model coronal magnetic fields. This workshop served to educate its
participants on the capabilities of fellow team members and to build bridges to
important external collaborators whose expertise on vector magnetograms
(Metcalf, Leka) and modeling (Mikic) will be very useful to our team.
The first
of our two recently purchased Sun Microsystems Sun Fire V880 workstations is
now up and running for MURI IVM data reduction, using the IVM scattered light
correction procedure we learned from Leka.
Thanks to its superior speed, we are able to use the full
"triplet" code for this data reduction. Regnier has already finished reducing more than 60 of the
over-100 magnetograms we have for NOAA 8210 before, during, and after its May
1, 1998 ~2240 UT eruption. As well, it
is being used by MSU undergrads Trish Jibben and Kendall Harwood (a participant
in the American Indian Research Opportunities program) for the reduction of
H-alpha spectroheliograms for the same day's data from the Hawaii MCCD Imaging
Spectrograph. Movies are being produced
of the motion of chromospheric material during the early stages of the
eruption. We plan to compare the
dynamics of the MHD simulations to these movies of the May 1, 1998 ~2240 UT
eruption.
The
quarter's nugget describes the method of topological field modeling presently
being applied to AR8210 (but using a different flare). This nugget is found at: http://solar.physics.montana.edu/muri/nuggets/jun2002/flare.html
. A compilation of all MSU nuggets is located at http://solar.physics.montana.edu/muri/nuggets/
.
Report
from Stanford: Sent by Yang Liu
In the
period from April 2002 to June 2002, we collected data and materials on the
1997 May 12 event that is in Yan Li's event list, and finished two papers on
origination of frontside full halo coronal mass ejections in the first half
solar cycle 23 and the super active regions in 22nd and 23rd cycles. We also
continued to collect and analyze solar magnetic field data. We produced and distributed daily synoptic
charts using both WSO and MDI data. We
produced a variety of synoptic frames used in others' analyses and produced
daily updates of synoptic charts using MDI data from longitudes other than central meridian.
Xuepu Zhao
and D. Webb studied all frontside full halo coronal mass ejections during the first half of solar cycle 23 to
search for possibility for prediction
of geomagnetic storms. They examine the locations of the frontside full halo
CMEs from 1996 to 2000 with respect to
two kinds of coronal closed field region: closed field regions between
opposite-polarity open field regions and closed regions between like-polarity open field regions. They found that
even during solar maximum when the occurrence frequency of the two kinds of regions is nearly the same,
the central positions of the frontside full halo CMEs are mostly located under
the coronal streamer belt. This in turn suggests that most full halo CMEs originate in the coronal helmet streamers
that are sandwiched between coronal
holes having opposite magnetic polarity. This finding and the solar cycle
evolution of the inclination of the heliospheric current sheet may be used, at
least partially, to understand the cause of the solar cycle effect on the storm-effectiveness
of frontside full halo CMEs.
1997 May
12 event is a complete halo CME associated with a C1.3 flare in the active
region NOAA8038 that is the only active region in solar disk. Observation also recorded eruption of
filament and EIT wave (see Webb, et al,
2000, JGR, 105, 27251). The kinematic property of this event was determined by
Zhao et al (2002) using the 'cone model' which show that this halo CME was
radially accelerated from 200 km/s at about 9.5 solar radii to 650 km/s at
about 24 solar radii, and the front acceleration is about 18.5 m/s^2. The speed
in the plane of the sky thereby ranges from 237 km/s to 307 km/s for the
asynptopic radial speed of 650 km/s
that consists with Sheeley's. (see Summary of
the paper for details). Unlike the 1998 May 01 event, a major event that
MURI groups are coordinately analyzing, the magnetic configuration in this event is much simpler and may
provide certain clues on understanding
of relationship of small-scale and large-scale fields, and thus is of high interest. We put collected materials, data and our
preliminary analysis at http://soi.Stanford.EDU/~yliu/may121997/event_May_12.html
.
In a
statistical study, we surveyed 29 super active regions that produced major flares and solar storms
in the 22nd and 23rd cycles, and
explored the properties of those regions.
We found
most of them have significant net magnetic flux, and present abnormal magnetic
configurations such as violating the
Hale-Nicholson Law, large tilt angle, and strong magnetic twist and
writhe. These active regions tended to occur preferentially in the certain
longitudes.
We are
continuing our effort on development and improvement of the magnetic synoptic
charts and test and evaluate the effectiveness and necessity of corrections we
suggest to be made.
The Zhao and Hoeksema (1995) CSSS magnetic field model is currently used to map magnetic fields into our solar wind analysis for use in real-time magnetic field forecasting associated with the IPS data analysis. To this end our group will employ Nick Arge of SEC NOAA to provide magnetic field maps from different observatories that are updated at regularly defined intervals (generally daily from ground-based observatories). These maps are presented in a standard format so that they can be easily compared and convected out to Earth using UCSD tomographic techniques. These maps will also be made available to the community via anonymous FTP at NOAA’s website. The ideas used in these analyses, their presentation and some of the worries and benefits of these updated data sets were presented at a MURI mini-workshop on April 15 at NOAA’s Space Weather Week April 15-19, 2002. These magnetic field maps are currently being obtained automatically at UCSD in real time as soon as they are available for use in the UCSD space weather forecast.
As an additional project, an interface has been built for different versions of the UCSD tomography program so that they can incorporate other’s 3D-MHD programs (or kinematic models) as a kernel instead of the currently used UCSD kinematic model. This is expected to provide a far better physical model for the UCSD tomography, necessary when SMEI begins to operate and will allow testing of each model incorporated. Because the UCSD tomographic technique allows a three-dimensional model to be obtained, we expect to use this technique to forward model solar wind features such as CMEs and corotating structures also observed in coronagraphs near the solar surface. The two programs first to be incorporated this way are the Tom Detman 3D-MHD code that is currently operating on UCSD computers and the HAF model currently operated by Ghee Fry and others at SEC NOAA.
In addition to graduate students Tamsen Dunn and Susan Rappoport, two additional students were hired and are currently employed using non-MURI funds at UCSD, but are working on associated projects. One of these students, graduate student Cindy Wang, is expected to help student Tamsen Dunn in the real-time access and analysis of magnetic field data. An undergraduate student is jointly hired by UCSD and SAIC’s Mickic, Linker and Riley to work on projects of mutual interest and eventually, the interface between the UCSD tomography program and the SAIC 3D-MHD programs.
A presentation (Jackson et al., 2002a) at the spring American Astronomical Society 200th meeting (joint with the Solar Physics Division) was successful. A presentation at Solar Wind 10 and the subsequent paper (Jackson et al., 2002b) is currently being readied for publication for these proceedings with UCSD’s Japanese colleagues.
References:
Jackson, B.V., P.P. Hick and A. Buffington, 3-D Tomography of Interplanetary
Disturbances, BAAS, 34, No. 2, 723, 2002a.
Jackson, B.V., P.P. Hick and A. Buffington, M. Kojima, M. Tokumaru, K. Fujiki, T. Ohmi and M. Yamashita, Time-dependent tomography of heliospheric features using interplanetary scintillation (IPS) remote-sensing observations, oral presentation to be submitted for publication in the proceedings of Solar Wind 10, Pisa, Italy, June 17-21, 2002b.
Zhao, X, and Hoeksema, J.T., Prediction of the
interplanetary magnetic field strength, J.
Geophys. Res, 100, 19, 1995.
A Mini-Workshop on CME Initiation was held
May 14-16, 2002 at the UNH campus in Durham, New Hampshire. At this workshop was to provide initial
conditions thatcan be used to test proposed mechanisms for the onset of CMEs.
The workshop was attended by participants from the University of New Hampshire,
the University of California at Berkeley, the University of Michigan, Montana
State university, The Naval Research Laboratory, and the Air Force Research
Laboratory. Three different modules
initial and boundary conditions modules were agreed upon which will be used to
investigate what kind of coronal current structures form during flux emergence
and whether some of the proposed eruptive mechanisms work as expected.
T.G.
Forbes, in collaboration with Dave Webb and Joan Burkepile, has adapted a previous
model for current sheet evolution in CMEs developed by Lin et al. (2000) to match observations of current-sheet-like
structures, called "rays", which are observed below CMEs. As shown in Figure 5, the model provides
predictions for the trajectory and expansion of the flux rope and the current
sheet during the acceleration phase of the eruption. The model also provides an explanation for the prominence
activation phase which precedes the appearance of the flare ribbons and
loops. (The occurrence of the latter
signals the appearance of the x-line.)
The main difference in the new model from the old is that the new one
uses a more realistic model for coronal density as a function of height. The old model assumed that the density
decreases exponentially with height which is only valid within a solar radius
of the surface. The new model
incorporates the more realistic density model of Sittler and Guhathakurta
(1999).

Figure 14
Model prediction by Lin et al. (2000)
for the evolution of a coronal mass ejection triggered by an ideal-MHD
instability. The letters SMM stand for
the Solar Maximum Mission satellite
launched by NASA in 1980.
As a result of this improvement in the
description of the ambient coronal density, the evolution of the CME current
sheet predicted by the theoretical model is in much better agreement with the
observed evolution of the rays. Since
this model includes an early evolution phase which is suggestive of the
pre-eruptive, activation phase in filaments, verification of the model during
its post-eruptive period strengthens the case that the model provides a
reasonable explanation of the physics underlying the activation phase.
T.G. Forbes has also published a review
(Forbes, T.G., Reconnection in different environments, in Physics of Magnetic Reconnection in High-Temperature Plasmas,
edited by, M. Ugai, Research Signpost, Kerala, India, in press, 2002) that
discusses the role of reconnection in coronal mass ejections among other
topics.
Publications Supported in Part or in Full by the Solar MURI
Grant
We
do not include abstracts at AGU or AAS meetings in this list; only publications
which have been submitted to a refereed journal or a topical conference
proceedings are provided here. More
details about talks and abstracts can be found in the quarterly reports in the
preceeding pages. These are publications
that involved some effort by MURI team members during the period reviewed in
this report.
W. P.
Abbett, G. H. Fisher, & Y. Fan “The Emergence of Magnetic Flux in Active
Regions”, IAU Symposium Vol. 203 pp 225-228 (2001).
W. P.
Abbett, G. H. Fisher "A Coupled
Model for the Emergence of Active Region Magnetic Flux into the Solar
Corona"., , ApJ, in press (2003)
Arge C.
N., Odstrcil,D., Pizzo V. J., and Mayer L., “A simple modular Sun-to-Earth
propagation model: Verification of model predictions”, Proc. of Solar Wind 10
Intl. Conf., Pisa, Italy, 17-21 June 2002, AIP, 2002. (submitted)
Casini,
R., and H. Lin “A classical model for the damped magnetic dipole oscillator”,
2002, ApJ, 571, 540.
Chae, J.,
Park, Y. D., Moon, Y.-J., Wang, H., Yun, H. S. 2002 "Temperatures of
Extreme-Ultraviolet-emitting plasma structures observed by TRACE" ApJ,
567, L159
Chae, J.,
Moon, Y.-J., Wang, H., Yun, H. S. 2002 "Flux cancellation rates and
converging speeds of canceling magnetic features" Solar Physics, 200, 73
Cho, K.
S., Kim, K.-S., Moon, Y.-J., Dryer, M. Initial results of Ichon radio spectrograph",
submitted to Solar Physics.
A.
Ciaravella, J. C. Raymond, J. Li, P. Reiser, L. D. Gardner, Y.-K. Ko, and S. Fineschi “Elemental Abundances and Post-CME Current
Sheet in a Very Hot Active Region”, 2002, ApJ (in press)
B. Debrunner, H., M.A. Lee, and J.M. Ryan, Production of high energy protons in large solar flare events, J. Geophys. Res., submitted, 2002.
Dobrzycka,
D., Raymond, J.~C., Cranmer, S. R., & Li, J “Ultraviolet polar coronal jets
and their relation to Soft X-ray jet events”, (2001), Multi-Wavelength
Observations of Coronal Structure and Dynamics Yohkoh 10th Anniversary Meeting,
E23.
Fan Y.,
Abbett W. P., Fisher G. H. : "The Dynamic Evolution of Twisted Magnetic
Flux
Tubes in a
3D Convecting Flow I: Uniformly Buoyant Tubes" ApJ, in press (2003)
Forbes, T.G., Reconnection in different environments, in Physics of Magnetic Reconnection in High-Temperature Plasmas, edited by, M. Ugai, Research Signpost, Kerala, India, in press, 2002.
Gallagher,
P.T., Denker, C., Yurchyshyn, V., Spirock, T.,
Qiu, J., Marquette, W. H., Wang, H., and Goode, P. R. "Space
Weather Research at Big Bear Solar Observatory" Annales Geophysicae,
accepted.
Gallagher,
P. T., Moon, Y.-J., Wang, H. "Active Region Monitoring and Flare
Forecasting" Solar Physics,
accepted.
Jackson B.V. and Hick, P.P., Corotational Tomography of Heliospheric
Features Using Global Thomson Scattering Data, Solar Phys., 2002 (submitted).
Yuan-Kuen
Ko, John C. Raymond, Jing Li, Angela Ciaravella, Joseph Michels, Silvano
Fineschi, and Rai Wu “SOHO/UVCS And Yohkoh/SXT Observation of a High
Temperature Corona Above an Active Region Complex”, Ap J, 2002 (in press).
Leamon, R.
J., Canfield, Richard C., and Pevtsov, Alexei A."Properties of magnetic
clouds and geomagnetic storms associated with eruption of coronal
sigmoids", , Journal of Geophysical Research, 107, (No. A9), p 1234
(2002).
Ledvina
S., Luhmann J. G., and Abbett: "A Magnetohydrodynamic Test of the
Wang-Sheeley
Model" (submitted to Solar Wind 10) (2002)
Lee, J.,
Moon, Y.-J., Kim, K.-S., Park, Y. D., Flectcher, A. B. "Statistical analyses of X-ray flare
predictions using solar maximum data", submitted to Solar Physics.
Jing
Li, Barry Labonte, Loren Acton, and
Grag Slater “Persistent Coronal Streamers and Identification of Sunspot
Clusters”, 2002, ApJ, 565, 1289
Li, J.,
Labonte, B., Acton, L., & Slater, G.
“The Nature of Large-scale and Long-lived Coronal Structures” (2001), Multi-Wavelength Observations of
Coronal Structure and Dynamics -- Yohkoh 10th Anniversary Meeting,
E64. Moon, Y.-J., Choe, G. S., Yun, H. S., Park, Y. D. 2002
"Force-freeness of solar
magnetic fields in the photosphere" ApJ, 568, 422
Yan Li, J. G. Luhmann, T. Mulligan, J. T.Hoeksema, C. N. Arge, S. P. Plunkett, O. C. St. Cyr “Earthward Directed CMEs Seen in Large-Scale Coronal Magnetic Field Changes: SOHO LASCO Coronagraph and Solar Wind” JGR Vol. 106, No. 111, pp 25103-25120.
Lin, J. T.G. Forbes, and P.A. Isenberg, Prominence eruptions and coronal mass ejections triggered by newly emerging flux, J. Geophys. Res., 106, 25053-25073, 2001.
J. Lin, A.A. van Ballegooijen, and T.G. Forbes, Evolution of a semi-circular flux rope with two ends anchored in the photosphere, J. Geophys. Res., in press, 2002.
Liu, Y.;
Zhao, X. P.; Hoeksema, J. T.; Scherrer, P. H.; Wang, J.; Yan, Y “On Formation of the Sigmoidal Structure in
Solar Active Region NOAA 8100”, 2002,
Solar Physics, 206, 333.
D.W.
Longcope and I. Klapper "A general
theory of connectivity and current sheets in coronal magnetic fields anchored to discrete sources" to Appear in Astrophysical Journal, vol. 579
J.G.
Luhmann, Yan Li, X-P. Zhao and S. Yashiro
"Coronal Magnetic Field Context of Simple CMEs Inferred from Global
Potential Field Models" Solar
Physics (submitted 2002)
J.G. Luhmann,
Yan Li (Space Sciences Laboratory, University of California Berkeley) C.N.
Arge (CIRES, University of Colorado and
NOAA-SEC) Todd Hoeksema and Xuepu Zhao (Stanford University) “A Solar Wind Source Tracking Concept for
Inner Heliosphere Constellations of Spacecraft”, submitted to SWX proceedings
P.C.H.
Martens and C. Zwaan "Origin and
Evolution of Filament-Prominence Systems", 2001, Astrophys. J., 558,
872-887.
P.C.H.
Martens "The Origin of Prominences
and Their Hemispheric Preferences for
Chirality
and the Skew of Overlying Loops", in: "Multi-Wavelength Observations
of Coronal Structure and Dynamics --
Yohkoh 10th Anniversary Meeting", COSPAR Colloquia Series, Vol. 13, P.C.H.
Martens and D. Cauffman (eds.), in press. (Elsevier: Dordrecht).
Moon,
Y.-J., Dryer, M., Smith, Z., Park, Y. D., Cho, K. S. 2002, "A revised
shock time of arrival(STOA) model for interplanetary shock propagation:
STOA-2" Geophys. Res. Letter, 29(10), 1029
Moon,
Y.-J., Choe, G. S., Park, Y. D., Wang, H., Gallagher, P. T., Chae, J., Yun, H.
S., Goode, P. R. "Statistical
evidence for sympathetic flares",
ApJ, accepted
Moon,
Y.-J., Chae, J., Wang, H., Choe, G., Park, Y. D. entitled with "Impulsive injection of magnetic
helicity associated with major flares", submitted to ApJ.
Moon,
Y.-J., Choe, G. S., Wang, H., Park, Y. D., Gopalswamy, N., Yang, G., Yashiro,
S. "A Statistical Study of Two
Classes of Coronal Mass Ejections", submitted to ApJ.
Moon,
Y.-J., Chae, J., Choe, G., Wang, H., Park, Y. D., Yun, H. S., Yurchyshyn, V.
B., "Flare activity and magnetic
helicity injection by photospheric horizontal motions", ApJ, accepted
Odstrcil
D., and Pizzo V. J., “ Numerical
simulation of interplanetary disturbances”,
in Proc. SOLSPA: The Second Solar Cycle and Space Weather
Euroconference, Vico Equense, Italy, 24-29 September 2001, pp. 281-284, ESA
SP-477, 2002.
Odstrcil
D., Vandas M., Pizzo V. J., and MacNeice P. J., “Numerical simulation of
interacting magnetic flux ropes”, Proc. of Solar Wind 10 Intl. Conf., Pisa, Italy,
17-21 Jun 2002, AIP, 2002 (submitted)
Qiu, J.,
Lee, J., Gary, D., Wang, H. 2002, "Motion of flare footpoint emission and
inferred electric field in reconnecting current sheets" ApJ, 565, 1335
Regnier,
S., Amari, T., Kersale, E. "3D Coronal magnetic field from vector
magnetograms: non-constant-alpha force-free configuration of the active region NOAA 8151", 2002,
A&A, 392, 1119
Regnier,
S., Amari, T., Canfield, R. C.
"Non-constant-alpha force-free field of active region NOAA 8210", to
appear in "Magnetic Coupling of the solar atmosphere", IAU Colloquium
188
Spirock,
T. J., Yurchyshyn, V. B., Wang, H. 2002, "Rapid changes in the
longitudinal magnetic field related
with the 2001 April 2 X20 flare" ApJS, 572, 1072
Tian, L.;
Liu, Y.; Wang, J. “The most Violent Super Active Regions in 22nd and 23rd
Cycles” , Solar Physics, 2002, in press.
Wang, H.,
Yurchyshyn, V. B., Chae, J., Yang, G., Steinegger, M., Goode, P. R. 2001, "Inter-Active Region Connection of Sympathetic Flaring on 2000
February 17". ApJ, 559, 1171
Wang, H.
and Qiu, J. 2002, "Relationship
between flare kernels in Halpha; far-blue wing and magnetic fields" ApJ,
568, 408
Wang, H.,
Gallagher, P. T., Yurchyshyn, V, Yang, G., Goode, P. R. 2002, "Core and
large scale structure of the 2000 November 24 X-class Flare and CME" ApJ,
569, 1026
Wang, H.,
Spirock, T. J., Qiu, J., Ji, H., Yurchyshyn, V. B., Moon, Y.-J., Denker, C.,
Goode, P. R. "Rapid Changes of Magnetic Fields associated with Six X-class
Flares" ApJ, accepted.
Yurchyshyn,
V. B., Wang, H., Goode, P. R., Yuanyong, D. 2001 "Orientation of magnetic
field in the interplanetary flux ropes and solar filaments" ApJ, 563, 381
Zhao,
X.P., S.P. Plunkett, and W. Liu
“Determination of geometrical and kinematical properties of halo coronal mass ejection using the cone model”,
2002, JGR, in press.
Zhao,
X.P.”The geoeffectiveness of frontside full halo coronal mass ejections” , 2001, Beijing COSPAR
Proceedings (ASR), in press.
X.P. Zhao
and D. F. Webb “The source region and storm-effectiveness of frontside full
halo coronal mass ejections” , 2002,
JGR, submitted.
[1] Note that the first annual report covered May 1 2001 – July 31 2001. After this year’s report, subsequent annual reports will report on work performed from July 1 – June 30 of each year.