High-latitude coupling processes between thermospheric circulation and solar wind driven magnetospheric currents and plasma convection

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The coupling between the ionized layers of the upper atmosphere and the thermospheric neutral gas is mediated through magnetic field changes and both field-aligned and ionospheric currents. This electrodynamic system is driven by processes of momentum and energy transfer, mainly reconnection, between the highly variable solar wind and its inherent interplanetary magnetic field with the magnetosphere and by innermagnetospheric plasma processes. These processes are particularly important at high latitudes, and they constitute a vital driving force for the transpolar thermospheric wind circulation. This project will use the unique situation that extensive data sets of the Cluster S/C (providing in-situ magnetospheric plasma observations) and accelerometer measurements of CHAMP and GRACE satellites (providing density and wind observations) are available over the last _7.5 years. The density and wind measurements are obtained by use of a relatively new observation technique, an accelerometer onboard the S/C. Global thermospheric wind data sets of this kind have not been available before. In the near future, other S/C missions using this technique will be launched as, e.g., the forthcoming Swarm constellation. Within this project, we will investigate the interdependence of plasma drift and thermospheric wind circulation at high latitudes, its dynamic changes and variability as directly driven by solar wind and IMF changes. The project has relevance for the space weather prediction tasks, and will prepare a new direction to exploit the existing and future satellite data.