MHD Simulation of Energy Transfer From the Solar Wind Into the Magnetosphere

Abstract. We use a 3D global magnetohydrodynamic (MHD) simulation code to examine the energy flow from the solar wind into the magnetosphere. We simulate two time periods: a major magnetospheric storm on April 6-7, 2000, and a substorm on August 15, 2001. During the storm event the energy input into the magnetosphere was highly enhanced, but during the substorm event the energy input was more typical. For the energy transfer calculation, a method for identifying the magnetopause surface from the simulation is developed. We calculate the total energy flux component normal to the magnetopause surface, thus giving the energy flux transferred from the solar wind into the magnetosphere. With this method we identify the locations on the magnetopause surface where significant energy transfer takes place. We also compare the time evolution of the total transferred energy to the time evolution of the empirical ε parameter calculated from the solar wind parameters. 1