Coupling of two computational models of the Earth's magnetosphere

The first major step has been completed in a long range project to merge the Fedder-Lyon Global 3D magnetohydrodynamic code and the Rice Convection Model (RCM) of the Earth's magnetosphere. Using MHD results as initial and boundary conditions, RCM runs were carried out for three different values of the energy invariant $\lambda$ of the plasma-sheet ions: $\lambda$ = negligibly small as in ideal MHD, $\lambda$ estimated from global MHD results, and $\lambda$ estimated from observations. In the first two runs, the RCM produced thin, well-defined patterns of region-2 magnetic-field-aligned currents shielding the inner magnetosphere from the convection electric field. These results differed substantially from the MHD result, indicating inaccuracy in the MHD code's numerical method when applied to the inner magnetosphere. The third run produced weak shielding and non-classic current patterns, which provide insight into the effect of plasma-sheet temperature on shielding