M-I Coupling: A Model for Ionospheric Velocity Structure in the High-Latitude F Region

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As coupled magnetospheric, ionospheric and thermospheric models mature it is increasingly apparent that Joule heating may take place over a wide variety of spatial scale sizes. Current models used for space weather estimate Joule heating rates by using average bulk plasma flow velocities (Vb) in large-scale high-latitude convection patterns. However, recent studies suggest that structure in the ion drift over smaller scale sizes of 10 to 100 km may change the estimated Joule heating rate by more than a factor of 2. This proposal will use data from the Dynamics Explorer-2 satellite and from the DMSP satellites to describe the average and maximum amplitude of velocity structure (AV) at high latitudes as a function of position, season, solar cycle and geomagnetic activity. Thus, Joule heating rates previously calculated using only the average bulk flow rate Vb of the plasma will be improved to become a function of Vb + AV. The data description will be cast in the form of a model that functionally describes the magnitude of the velocity structure in terms of the bulk flow so that these refined estimates of Joule heating rates can be easily used both in thermospheric models and as boundary conditions for coupling magnetospheric models with the ionosphere. A first order dependence of the model on magnetic activity will allow a better specification of the high latitude thermosphere and ionosphere for space weather applications.