Polar cap potential during magnetic storms: MHD simulations

In this paper, we will examine the variation of the polar cap potential during magnetic storms using global magnetohydrodynamic (MHD) simulations of the interaction of the solar wind with the magnetosphere. We present the time evolution of the polar cap potential and correlate changes in the potential with changes in the solar wind input during three events. We show that the simulation potential behaves very similar to predictions based on the solar wind electric field, but that there is also a noticeable dependence on solar wind density, with higher values of polar cap potential for larger values of solar wind density.