Solar‐wind influence on MLT dependence of plasma sheet conditions and their effects on storm time ring current formation

Abstract

By applying plasma sheet boundary conditions based on averages of Geotail data to a magnetically self‐consistent ring current simulation model, we investigate how solar‐wind influence on plasma sheet conditions affects local‐time asymmetries in early ring current development under two representative interplanetary conditions: (1) For strongly northward interplanetary magnetic field (IMF), high solar‐wind density, and low solar‐wind speed, Geotail ion densities are high and ion temperatures are low, particularly in the post‐midnight quadrant at radial distances r > 8 RE; and (2) For weakly northward IMF, high solar‐wind speed, and low solar‐wind density, a significant density enhancement is not observed in the post‐midnight at r > 8 RE. Within an hour after an increase in the convection electric field, Condition (1) lead to relative enhancement of the simulated ring current plasma pressure especially in the post‐midnight quadrant, while Condition (2) lead to pressure enhancements that are more uniformly distributed around the night side.