Magnetospheric convection at Saturn as a function of IMF BZ

Abstract

We have used three dimensional magnetohydrodynamic simulations to investigate the influence of the interplanetary magnetic field (IMF) on Saturn's magnetosphere for cases with no IMF, northward and southward IMF. The subsolar magnetopause and bow shock positions are sensitive to changes in the solar wind dynamic pressure but insensitive to changes in the IMF. Without an IMF vortices were generated near dawn where the corotating flows and solar wind are opposite. For Bz < 0 the vorticity results from the interaction of flows driven by cusp reconnection and corotation. For Bz > 0 vortices were generated in the morning and evening where the flows from tail reconnection are opposite to the solar wind and corotation. We used the energy flux to the ionosphere and upward field-aligned currents (FACs) as proxies for diffuse and discrete aurora. Strong upward FACs extend to the morning sector when Bz > 0. The strongest FACs are generated in the flow vortice. Copyright 2007 by the American Geophysical Union.