An Event Comparison of Global MHD Simulation and SuperDARN HF Radar in the North Polar Cusp

On June 5, 1998 a number of the Northern Hemisphere SuperDARN HF radars recorded good backscatter in the cusp region from ~14:00 to 16:00 UT, from which maps of ionospheric convection and backscatter widths have been derived. For comparison the time-varying Lyon-Fedder Global MHD model of this event has been simulated using IMP-8 and WIND spacecraft measurements of solar wind input. The time interval of interest is characterized by negative IMF Bz and negative IMF By following a positive IMF Bz interval. Good correspondence is found between the MHD model and the SuperDARN ionospheric convection patterns confirming that this is an excellent event for a detailed comparison of model and observation. The parameters to be compared include: ionospheric footprints of the MHD cusp plasma versus the location of large SuperDARN backscatter widths; MHD dayside open-closed field line boundaries versus SuperDARN determined open-closed boundaries and the convection flows relative to these boundaries; footprints of MHD merging regions versus features in the SuperDARN convection and backscatter widths. The overall purpose of these comparisons is to understand the SuperDARN observations in the context of the 3D magnetosphere and to investigate how SuperDARN can be used to identify cusp and magnetic merging regions.