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This project's mission is to study the underlying mechanisms that control the chain of coupling between the solar wind, magnetosphere and ionosphere. In the first year of this project, a study was initiated to determine the global response of the high-latitude ionosphere to forcing by magnetosphere substorms. An assimilative model was used with ground-based radar, magnetometer and satellite measurements to differentiate substorms surge convection signatures form the ambient pre-substorm two cell pattern. This study concluded that the perturbed convection pattern can he characterized by a small-scale two-cell "expansion" structure superimposed on a global-scale two cell pattern. The characterization of these intermediary potential patterns is an essential first step toward the creation of fully time-dependent polar convection models. Subsequent work on this project has focused on identifying ground-based techniques to determine the location of the open-closed field line boundary. Accurate determination of this boundary is required for studies of substorm evolution, for comparisons of polar cap to auroral zone on composition profiles for precise calculation of the reconnection electric field and for studies of global polar cap inflation and deflation. A summary description of the results from this new research follows. (MM)