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 fo r the time between 1200 UT May 19 and 0200 UT May 20, 1996, with a three-di mensional MHD model. This time period has been chosen as an International S olar-Terrestrial Physics/Global Geospace Science event for community study, and there is a large set of data with which to compare. In this paper we w ill compare the simulation predictions with results from the Assimilative M apping of Ionospheric Electrodynamics (AMIE) analysis. We show comparisons for the convection, the amoral precipitation, the ionospheric conductances, the field-aligned currents, and the Joule heating distribution. The result s concentrate on four time periods when the two DMSP spacecraft, F12 and F1 3, and the POLAR spacecraft were passing over the northern (summer) polar r egion. 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 somewh at higher in the MHD model. The auroral electron precipitation energy flux from the MHD model is too low, particularly in the late morning, when compa red with the POLAR UVI data because of the lack of electron drift physics i n the model. We show how the MHD auroral input can be improved by adjusting the parameters in the auroral precipitation model.