Radar studies of mid-latitude ionospheric plasma drifts

We use incoherent scatter radar measurements from Millstone Hill and Saint Santin to study the midlatitude F region electrodynamic plasma drifts during geomagnetically quiet and active periods. We present initially a local time, season, and solar flux dependent analytical model of the quiet time zonal and meridional ExB drifts over these stations. We discuss, for the first time, the Saint Santin drift patterns during solar maximum. We have used these quiet time models to extract the geomagnetic perturbation drifts which were modeled •s • function of the time history of the auroral electrojet indices. Our results illustrate the evolution of the disturbance drifts driven by the combined effects of prompt penetration •nd longer lasting perturbation electric fields. The meridion•l electrodynamic disturbance drifts have largest amplitudes in the midnight-noon sector. The zonal drifts •re predominantly westward, with largest amplitudes in the dusk-midnight sector •nd, following a decrease in the high-latitude convection, they dec•y more slowly th•n the meridional drifts. The prompt penetration •nd steady state zonal disturbance drifts derived from radar measurements •re in good agreement with results obtained from both the ion drift meter data on board the Dynamics Explorer 2 (DE 2) satellite •nd f?om the Rice Convection Model.