A General Cone Model Approach to Heliospheric CMEs and SEP Modeling

1
Overview of CISM Solar/Heliosphere Research From
Solar Wind to SEP Events J.G. Luhmann, D.
Krauss-Varban, Y. Li, S. Ledvina, C.O. Lee, W.
Abbett, B. Lynch1, J.A. Linker, P. Riley, Z.
Mikic, R, Lionello2, D. Odstrcil3,4, Y. Liu, X-P.
Zhao5, C.N. Arge6 1 University of California,
Berkeley, 2SAIC, 3 University of Colorado,
4NOAA-SEC, 5Stanford, 6AFRL
This poster provides an update on the approach
that CISM is taking to develop a physics-based
model of the coupled corona and solar wind,
including the transient disturbances known as
CMEs. As a first case study of a Coronal Mass
Ejection (CME) event, CISM chose a relatively
simple halo CME in May 1997 that was
well-observed at the Sun and had geospace
effects. Major progress on the initiation of
that event is described in an acoompanying
poster. A n approach known as the Cone Mode (of
CMEs)l is being developed as a simpler
alternative to modeling many events in the
heliosphere, and to enable the addition of the
solar energetic particle component of
heliospheric space weather. The Cone Model is
also highlighted in an accompanying poster.
Comparisons of the models with observations are
regularly used to guide their development and
adjust strategies..
Magnetogram-based quiet corona and solar wind
model
The recent corona has been very quiet, dominated
by several large low latitude coronal holes.
These have produced an ideal period to see if the
model can also reproduce the solar wind stream
structure.
SOHO MDI synoptic map for CR1913 (left) and
(below) modeled magnetic field lines, and
simulated SOHO EIT EUV images, These illustrate
the ability of the coronal model to reproduce
coronal holes-the solar wind sources. The coronal
model couples to the solar wind model (right) to
produce CISMs CORHEL.
Selected Halo CME Event,
Coupled Model Grids
At left are plots of coronal magnetic field lines
from a GONG Website that uses one of our models.
At right is a plot from the CCMC-showing solar
wind results.
Local Solar Wind parameters can drive the
magnetosphere simulation SEPs enter the
magnetosphere along open field lines and at low
latitudes on occasion. Our models can replace the
data in both cases.
(Images, from J. Linker, P. Riley, Z. Mikic)
(V. Pizzo)
Student C. Lee runs the coupled models at the
CCMC to compare (above) the measured and modeled
solar wind
Time-dependent corona and CME Initiation-A Case
Study
Observed sites of other CMEs show two distinctive
coronal magnetic field settings involved in
simple CMEs. These.show initial field geometries
with both simple (parallel) active region and
overlying coronal field geometries and multipolar
geometries with magnetic null points. Both are
being tested to determine if the resulting
eruption properties depend on the initial field
geometry.
Selected Halo CME Event, May 12, 1997
Major progress is being made in modeling the
details of one specific well-observed event (See
CME Initiation Poster). Other CMEs (right) from
the region can tell us if the same initiation
mechanism repeats.
SOHO (LASCO, EIT, MDI) Images and magnetogram
SOHO and Yohkoh data plots from Y. Li (left)
and modeled pre-CME field geometries of two
types from B. Lynch (right)
A General Cone Model Approach to Heliospheric
CMEs and SEP Modeling
STEREO and ACE mission data will provide unique
opportunities to test our model of SEP events at
several locations at once- to see if we reproduce
this classical concept.
Observer Shock-connected field lines in the Cone
model give SEP source location and strength.
CISMs Cone Inversion Model of CMEs uses 2D
coronagraph images of halo CMEs to estimate the
location, orientation, and properties of a 3D
cone-shaped disturbance that may be used to
simulate a CME injection in the solar wind
simulation. This scheme, developed under MURI,
is now a CORHEL option (see Cone Model poster)

IMP-8 data, Plot from A. Tylka
(D. Odstrcil)
The SEPs are modeled as a passive test particle
(ion) population in a post-process approach that
uses the MHD model shock to characterize shock
source injections, and the time-dependent
modeled magnetic field lines between the Sun and
a selected observer location to define the path
of transport from the shock.
(SOHO LASCO images)
ENLIL boundary conditions from MAS, May 12 97
event showing cone model injection
location. (From D. Odstrcil and X-P. Zhao.)
Shock strength from the May 12.97 event cone
model (left, from S. Ledvina) and modeled SEP
proton event time profile (above)