MHD simulations of solar and interplanetary phenomena

Abstract

Workers in the field of magnetohydrodynamics (MHD) have been interested in the hypothesis that observed solar activities can be utilized in a deterministic way to predict the bulk flow consequences of these activities in the three-dimensional heliosphere. Exploration of this hypothesis, using the conventional/classic initial boundary value approach, will be reviewed against the background of basic, ideal (except for shocks) one-fluid approximations. This work has been divided into two parts: near-Sun simulations in two dimensions of coronal mass ejections (CMEs) as well as interplanetary simulations in 2D and 3D of propagating shocks. In the latter case, the flows behind the shocks should be thought of as interplanetary “ICMEs”, i.e., the interplanetary, evolutionary consequences of the near-Sun simulations.

Initialization of these simulations has been based on observations (optical, soft X-ray, radio) from both ground-and space-based instruments. Simulation outputs have been compared within situ plasma and field observations and interplanetary scintillations (IPS). Improvements in the initialization procedures — spatial/temporal variations of solar plasma and field parameters at the coronal base — are expected from YOHKOH, SOHO, CORONAS-I, and TRACE experiments. “Ground truth” observations from WIND, SOHO, ACE, and INTERBALL experiments should then be compared with three-dimensional MHD outputs in tests of the fluid hypothesis noted above.