• Saturn;
  • magnetosphere;
  • MHD simulation

[1] We have carried out a global magnetohydrodynamic simulation study of the dynamic response of Saturn's magnetosphere to northward IMF. The response can be separated into three states. Early in the simulation (state 1) vortices form on the dayside magnetopause and propagate tailward. They form first in the morning and then in the afternoon. The flows around the dawn vortices are clockwise while double vortices form at dusk with both clockwise and counterclockwise flow. The magnetopause vortices are like those associated with the Kelvin-Helmholtz instability. Shortly after the northward IMF reaches the subsolar magnetopause reconnection begins at the equator. Later the reconnection occurs above and below the equator creating magnetic O-regions at the magnetopause (state 2). Finally late in the simulations a series of neutral lines forms in the tail (state 3).