An extensive data base of on-site and ground based data is used to describe various features of the electrodynamics and plasma composition in the ionosphere. This proposal describes an effort to interpret observational phenomenon with the aid of simple and sophisticated computer models containing some of the basic physics of a particular phenomenon. Comparison of the predicted and observed behavior is used as an indicator of the adequacy of the physical description and as a confirmation of our understanding of the phenomenon. The following features will be studied with this approach: The scale-size dependency of electric field mapping and its effects on the expected relationship between field and currents and particle precipitation. The effects of winds and waves in the bottomside F-region on the generation of large scale dynamo fields and smaller scale intermediate plasma layers. The response of the ionosphere to large sub-auroral ion drifts with varying evolution times. *** //
