THE AURORAL OVAL BOUNDARIES ON JANUARY 10, 1997 - A COMPARISON OF GLOBAL MAGNETOSPHERIC SIMULATIONS WITH UVI IMAGES

We present a global magnetospheric simulation of the initial period of the January 10-11, 1997 magnetic cloud event. Model magnetospheric bo undaries mapped to the ionosphere are compared to UVI images of the au roral oval from 1:00 to 4:30 UT. The convection reversal boundary gene rally matches the UVI equatorward boundary and is almost always polewa rd of the boundary separating Region 1 and Region 2 currents. The sepa ratrix between open and closed magnetic field lines matches the polewa rd boundary of the UVI images well during quiet periods. During dynami c periods when the separatrix moves several degrees in latitude in som e sectors, the poleward boundary of the Region 1 currents matches the UVI images better.