Coupling between the solar wind and the magnetosphere during strong driving: MHD simulations

We examine the simulation of the January 10, 1997, magnetic storm using the Lyon--Fedder--Mobarry three-dimensional magnetohydrodynamic simulation of the interaction of the solar wind with the magnetosphere. We explore the response of the energy coupling between the solar wind and the magnetosphere during the extreme solar wind conditions produced by magnetic cloud that hit the Earth's magnetosphere during the first half of January 10. During the early part of the event, the simulation produced substorm-like behavior marked by a loading and unloading of stored magnetic flux. However, during the period of strong, sustained solar wind energy input, the loading--unloading behavior essentially goes away and the simulation entered a directly driven phase. During this direct-driving phase the solar wind dynamic pressure controlled the ionospheric Joule heating in the simulation.