Global MHD modeling of the impact of a solar wind pressure change

A sudden increase in the solar wind dynamic pressure compresses the magnetosphere and launches compressional waves into the magnetosphere. The global response of the magnetosphere, including the ionosphere and the location of the field‐aligned current (FAC) generation, to a step increase in the solar wind density has been studied using a global three‐dimensional adaptive MHD model. As the density increase propagated along the flanks of the magnetopause, a two‐phased response was seen in the ionosphere. The first response was an increase in FACs near the polar cap. For this response we found the location of FACs to lie just inside the magnetosphere. The second response was an increase in FACs at lower latitudes. The increase in FACs was in the same direction as region 1 currents. For the second response we found the location of FACs to fall well within the magnetosphere.