Time-Dependent Coupling of Lfm-Helio and MAS Models for CME Propagation

Abstract:

We present initial results of coupling of the heliospheric adaptation of the Lyon-Fedder-Mobarry (LFM) magnetohydrodynamic (MHD) model — LFM-helio — with the MAS model of the solar corona. Up to now, LFM-helio has been limited to steady-state solutions dominated by corotating structures. We have developed a generalized interface for specification of time-dependent coronal boundary conditions and ingestion of MAS simulation data into the LFM model. The coupling is done by overlapping the LFM inner boundary buffer region with the outer portion of the MAS coronal grid. LFM-helio operates in the inertial rest frame, but our coupling code is sufficiently flexible that MAS solutions performed in either rotating or inertial frames can be ingested. We present results of a number of idealized coupled MAS/LFM-helio simulations — ranging from simply symmetric solar wind background to realistic including high and slow speed streams — intended to test the interface for seamless propagation of transients from the corona into the inner heliosphere domain. The transients are then tracked to larger heliocentric distances — to Earth and beyond. We specifically investigate the magnetic structure of the CMEs as they propagate through the interplanetary medium including rotation and erosion, and consider how the simulation resolution affects the results. We also developed codes for creation of synthetic white-light heliographic images which are used to help track CMEs kinematics through J-maps and put the simulations into a realistic observational context.