An MHD simulation of energy flow in the solar wind, magnetosphere, and ionosphere system: Steady convection events

Abstract

We have used a global magnetohydrodynamic simulation code to model the magnetospheric configuration which results when the interplanetary magnetic field is southward for an extended period. For the first two hours the simulation results are like those expected from the near-Earth neutral line model of magnetospheric substorms in which the southward IMF leads to dayside reconnection and the storage of magnetic energy in the tail lobes. The kinetic energy in the magnetosphere also increased as convection increased. The near-Earth neutral line started on closed plasma sheet field lines and then progressed to lobe field lines. This resulted in a conversion of magnetic energy in the tail lobes into kinetic and thermal energy in the plasma sheet. Then the system relaxed into a steadily convecting state characterized by a balance between the dayside reconnection and the reconnection in the near-Earth tail. This steadily convecting magnetosphere was maintained for the remaining two hours of the simulation.