HR: 08:30h
AN: SM51C-03    [Abstracts]
TI: MHD Simulations of Solar Wind-Geospace Coupling
AU: * Hernandez, S
EM: hernands@fit.edu
AF: Florida Institute of Technology, Department of Physics and Space Sciences, Melbourne, FL 32901, United States
AU: Lopez, R E
EM: relopez@fit.edu
AF: Florida Institute of Technology, Department of Physics and Space Sciences, Melbourne, FL 32901, United States
AU: Wiltberger, M
EM: wiltbemj@ucar.edu
AF: High Altitude Observatory, National Center for Atmospheric Research, Boulder, CO 80301, United States
AU: Lyon, J G
EM: lyon@tinman.dartmouth.edu
AF: Dartmouth College, Department of Physics and Astronomy, Hanover, NH 03755, United States
AB: We present a study of transpolar potential using global MHD simulations of the solar wind magnetosphere interaction. The role of Region 1 currents in producing saturated transpolar potential is discussed in terms of the dissipation of solar wind mechanical energy before the solar wind actually reaches the magnetopause. The simulations show that the bow shock has a current that closes with Region 1 type currents flowing on open magnetic field lines. During strongly southward IMF, a large current must flow on the bow shock to satisfy the jump conditions. The bow shock current exerts a JxB force on the solar wind that is larger than the Chapman- Ferraro current, dissipating most of the solar wind mechanical energy far from the magnetopause. Under these conditions, the bow shock closure currents become a major factor in determining the ionospheric potential, and the force balance at the bow shock controls the magnetosheath parameters, and hence the reconnection rate. This results in a reduced electric field applied at the magnetopause and a smaller potential due to magnetopause reconnection. Since the primary driver of the polar cap potential is determined by the electric field applied the magnetopause, the polar cap potential is reduced, leading to the saturation effect. However, the ionospheric potential can also be modulated by the current required to close the bow shock current.
DE: 2721 Field-aligned currents and current systems (2409)
DE: 2736 Magnetosphere/ionosphere interactions (2431)
DE: 2740 Magnetospheric configuration and dynamics
DE: 2753 Numerical modeling
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Joint Assembly