Modeling The 3D Density Structure and White-Light Appearance of CME Events

ROSES ID: NNH05ZDA001N      Selection Year: 2006      

Program Element: Independent Investigation

Principal Investigator: Ward Manchester

Affiliation(s): University of Michigan

Project Member(s):
Vourlidas, Angelos Co-I JHU/APL
Roussev, Ilia Iankov Collaborator University of Hawaii

Summary:

We propose to examine the propagation of solar eruptive events to 1 AU

in a realistic heliosphere using a global magnetohydrodynamic (MHD) model.

The main focus of this study will be the evolution of the 3D density

structure of the CME and how it relates to Thomson-scattered white

light images. The University of Michigan's BATSRUS code will used to

perform the proposed simulations. CME initiation will follow from

both flux ropes and (Gibson & Low, 1998) and imposed shearing motions.

Our earlier simulations have produced many important results. We have

shown that the mass of fast CMEs increases by as much as a factor of

four as they propagate to Earth because of plasma swept up by the

CME-driven shock. We have also shown that line-of-sight measurements

of CME mass may significantly underestimate the mass swept up by a

CME if a dense spherical shell encases a low density cavity. Expansion

of the CME flux rope has also been shown to cause the dense core to

evolve to a density depletion. These results have been published a

series of papers: Manchester el al. (2004a, 2004b) Lugaz, Manchester

and Gombosi (2005). This proposal seeks funds to significantly

advance this research in 4 ways: (1) incorporate a more realistic

MHD model of the inner heliosphere based on solar magnetograms,

(2) investigate the pre-eruption conditions at the Sun based on

magnetic data for chosen active regions and use this data to direct

CME initiation, (3) comparing the CME synthetic white light images

with LASCO observations near the Sun and images obtained near 1 AU

with STEREO. We will examine the 3D model density structure of CME

disturbances and line-of-sight images to determine what may be

accurately inferred about the density, velocity and energy of

CMEs from single and stereoscopic views. Understanding the CME

morphology will allow us to separate the shock from the driver and

will lead to more accurate measurements of the physical parameters such

as the compression ratio, speed, mass, and location. In the case of

shocks, the compression ratio and speed are necessary inputs

in models of particle acceleration. Understanding how the various

CME structures evolve through the heliosphere will enhance the

scientific return from the numerous in-situ instruments. It will

also help us investigate what causes some CME to be geoeffective.

Obtaining realistic CME models throughout the heliosphere will greatly

enhance the return from the SECCHI observations by (1) providing

examples of how certain CME structures (shock, flux rope) will look

at different heliocentric distances and perspectives, and (2) act

as a controlled data set upon which to test the fidelity of the 3D

reconstruction algorithms.

Presentations:

Performance Year	Reference	Actions
1	Cohen, Ofer; Sokolov, Igor; Gombosi, Tamas; Roussev, ...

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