Articles | Volume 27, issue 8
Ann. Geophys., 27, 3275–3286, 2009
https://doi.org/10.5194/angeo-27-3275-2009

Special issue: Three eyes on the Sun – multi-spacecraft studies of...

Ann. Geophys., 27, 3275–3286, 2009
https://doi.org/10.5194/angeo-27-3275-2009

  21 Aug 2009

21 Aug 2009

4-D modeling of CME expansion and EUV dimming observed with STEREO/EUVI

M. J. Aschwanden M. J. Aschwanden
  • Solar and Astrophysics Laboratory, Lockheed Martin ATC, 3251 Hanover St., Bldg. 252, Org. ADBS, Palo Alto, CA 94304, USA

Abstract. This is the first attempt to model the kinematics of a CME launch and the resulting EUV dimming quantitatively with a self-consistent model. Our 4-D-model assumes self-similar expansion of a spherical CME geometry that consists of a CME front with density compression and a cavity with density rarefaction, satisfying mass conservation of the total CME and swept-up corona. The model contains 14 free parameters and is fitted to the 25 March 2008 CME event observed with STEREO/A and B. Our model is able to reproduce the observed CME expansion and related EUV dimming during the initial phase from 18:30 UT to 19:00 UT. The CME kinematics can be characterized by a constant acceleration (i.e., a constant magnetic driving force). While the observations of EUVI/A are consistent with a spherical bubble geometry, we detect significant asymmetries and density inhomogeneities with EUVI/B. This new forward-modeling method demonstrates how the observed EUV dimming can be used to model physical parameters of the CME source region, the CME geometry, and CME kinematics.