Response of High-latitude Ionospheric Plasma Convection during Storms across Multiple Scales

Abstract:

This study examines the response of the high-latitude plasma motion during the intense geomagnetic storm (Dst ~ -130 nT) that occurred on 17 March 2013 (known as St. Patrick’s Day event). Multiple DMSP satellite measurements are available to investigate the topside ionospheric plasma motion at different temporal and spatial scales. During the storm time, rapid changes in the flow structures occur within a time scale of 10-20 minutes, which also can be interpreted as moving meso-scale flow perturbations through a fixed volume. The Heelis convection model, compatible with an expanding-contracting polar cap paradigm, is used to reconstruct the instantaneous large-scale plasma convection pattern during this storm. Changes in the electric potential associated with the polar cap boundary motion are based on multiple DMSP measurements. The expansion and contraction of the large-scale pattern is mainly associated with changes in the IMF Bz. Modification in the potential distribution in the polar cap region are associated with the IMF By. The penetration electric field, which is correlated well with the Dst index, also can be seen in the DMSP observations.