A Theoretical Study of Time-Dependent Magnetosphere Ionosphere Coupling

9301043 Lysak The primary goals of the first GEM campaign are an understanding of the mapping of dayside magnetopause processes to the ionosphere and a determination of the ionospheric signatures of such processes. Although previous attempts have been made to consider the static mapping of magnetopause processes to the ionosphere, the fact that the Alfven transit time from the magnetopause to the ionosphere is comparable to the evolution time of magnetopause processes suggests that the dynamics of this coupling is important. This proposed work focuses on an investigation of these effects by means of a three-dimensional model of coupling of the magnetosphere and ionosphere by means of Alfven waves which considers the global, linear response of the magnetosphere and ionosphere to perturbations at the magnetopause. In this model, perturbations representing magnetopause processes such as transient reconnection, Kelvin-Helmholtz instabilities or dynamic pressure pulses can be imposed on the magnetopause, and the resulting ionospheric signature can be self-consistently calculated. This model will be extended to include finite pressure effects, finite ionospheric conductivity and a generalized magnetic field geometry. This project will be supported by two related projects, one of which considers a localized model of a diverging auroral flux tube which includes nonlinearities, ionospheric dynamics and parallel electric fields. The other related project is an investigation of transport processes at the magnetopause and their role in the generation of field-aligned currents. The numerical results will be compared with data from ground magnetometer arrays in order to determine the most likely source for the observed magnetic vortices. ***