Comparison of global MHD simulations with AMIE simulations for the events of May 19-20, 1996

Using WIND-measured solar wind data, we have simulated the magnetosphere for the time between 1200 UT May 19 and 0200 UT May 20, 1996, with a 3D MHD model. This time period has been chosen as an International Solar-Terrestrial Physics/Global Geospace Science event for community study, and there is a large set of data with which to compare. We compare the simulation predictions with results from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) analysis. We show comparisons for the convection, the auroral precipitation, the ionospheric conductances, the field-aligned currents, and the Joule heating distribution. The results concentrate on four time periods when the two DMSP spacecraft, F12 and F13, and the POLAR spacecraft were passing over the northern (summer) polar region. The comparisons show excellent agreement with the F13 electric field measurements. The ionospheric convection patterns agree well between the simulation and the AMIE analysis with the cross polar potential drop somewhat higher in the MHD model. The auroral electron precipitation energy flux from the MHD model is too low, particularly in the late morning, when compared with the POLAR UVI data because of the lack of electron drift physics in the model. We show how the MHD auroral input can be improved by adjusting the parameters in the auroral precipitation model. (Author)