Simulating Magnetosphere-Ionosphere Coupling in TIE-GCM

At high latitude there is a strong coupling between the magnetosphere and ionosphere. Modeling the full coupling can be very expensive since a magnetosphere model has to coupled to an ionosphere model. Therefore most general circulation models (GCM) approximate the high latitude coupling to the magnetosphere by using empirical models [Weimer 2005, Heelis 1982] which specify the high latitude convection pattern for different geo-space conditions. This research aims to show the viability of the Thermosphere Ionosphere Electrodynamics General Circulation Model (NCAR-TIEGCM) [Richmond et al., 1992] in its ability to model the magnetosphere-ionosphere coupling not only using a prescribed electrical potential from the empirical model [Heelis 1982] but also to show that it can accurately represent the coupling using field-aligned current (FAC) consistent with the prescribed electric potential. Using the field-aligned current to drive the high latitudes has the advantage that the neutral wind effects can be considered everywhere instead of using a prescribed empirical electric potential pattern. In addition with new data from the AMPERE satellite being available the TIE-GCM has the option to be driven by more realistic spatial and temporal distribution of the energy input. Further: the viability of the TIEGCM, if shown to correctly employ the FAC current to represent the magnetosphere-ionosphere interaction, as it does using the electric potential, this will expand ways to represent the magnetosphere as it couples to the ionosphere. Then the TIEGCM usage of numerically modeling the upper atmosphere will have expanded.