Comparison of the high-latitude ionospheric electrodynamics inferred from global simulations and semiempirical models for the January 1992 GEM campaign

Abstract

The global characteristics of the auroral oval during the Geospace Environment Modeling (GEM) campaign of January 1992 are investigated through four different models: the assimilative mapping of ionospheric electrodynamics (AMIE) technique, the IZMIRAN electrodynamic model (IZMEM), the Weimer ionospheric convection model, and three-dimensional global fluid simulations. It is shown that all four models predict essentially the same key features with respect to the position, shape, and extent of the auroral convection cells, including the position of the separatrix between open and closed field lines. The relative change in the magnitude of the cross-polar cap potential is about the same for the different models, being between 20% and 50% in the case studies examined. However, there is some discrepancy by a factor of about 2 in predicting the absolute value. The global simulation potential is highest because it includes convection at low to middle latitudes, which appears to add about 50 kV to the total potential. It is shown that the auroral field-aligned currents are very sensitive to changes in Bz interplanetary magnetic field, with changes of the order of 200-300% in the total integrated current being inferred for the above changes in potential. The increase, particularly for the highest activity period, is due to an increase in the area of the oval rather than an increase in intensity. Copyright 1997 by the American Geophysical Union.