Magnetopause Standoff Position and Its Time-Dependent Response to Solar Wind Conditions: Models and Observations

Abstract:

We model changes in the magnetopause position due to solar wind increases in solar wind dynamic pressure and step functions in the IMF Bz component observed during 4 hours on March 24, 2001. The study uses the Run-On-Request capabilities within the MHD models available from the Community Coordinated Modeling Center (CCMC) at NASA Goddard Space Flight Center, specifically BATS-R-US, OpenGGCM, LFM and GUMICS models. The magnetopause standoff position prediction and response time to the solar wind changes will then be compared to results from available empirical models (e.g. Shue et al. 1997), and to Cluster and the Geotail missions magnetopause crossing observations. Rigorous analysis/comparison of observations and empirical models is critical in determining magnetosphere dynamics for model validation. We will identify solar wind conditions that affect the model predictions significantly and lead to differences between the models. Preliminary results show that the magnetopause standoff position takes about 4/3 of an hour to respond to the simulataneous increase in dynamic pressure and IMF Bz changes at the March 24, 2001 event.