Initial results from the simulation of the halloween 2003 storms

In this paper, we present initial results from a global MHD simulation of the Halloween 2003 storms. The simulation seems to be representing well the global configuration of the magnetosphere based on comparison to geosynchronous observations. The global configuration showed a highly variable magnetospheric size, at times 40% the size of the regular magnetosphere. The simulation also reproduces the saturation of the polar cap potential, albeit at larger values than are observed, and there is evidence that the Chapman-Ferraro current is not exerting the primary force balance with the solar wind when the polar cap potential saturates. Moreover, the simulation develops an asymmetry in the polar cap potential during the saturation periods, with the higher conductivity polar cap having a lower saturation potential.