Temporal and spatial effects of Subauroral Polarization Streams on the thermospheric dynamics

Based on two years of Subauroral Polarization Streams (SAPS) events detected by DMSP satellites in the dusk-premidnight sector, we have studied the temporal and spatial effects of SAPS on thermospheric quantities. The events are divided into two different MLT (magnetic local time) groups covered by F13 and F14/15. Concurrent CHAMP observations taken between −30° and +60° in longitude (−2 h and +4 h MLT) with respect to the SAPS detection location and within a time window of 1.5 h before and 3 h after the SAPS detection time are used for comparison. For the first time the spatial and temporal effects of SAPS are shown. SAPS have great influences on the zonal wind in all MLT bins (17–21 MLT) around the F13 MLT sector, with the largest effect appearing around 19 MLT, about 0–2 hours MLT after SAPS onset. SAPS have relatively little effect around 23–24 MLT, as deduced from F14/15 SAPS. For most cases the zonal wind peaks in the first orbit, concurrent with the SAPS onset. But around 19 MLT the zonal wind attains peak velocities about 1.5 h after the SAPS detection. This is claimed to be related to the longer persistence of SAPS events in this MLT sector than in other sectors. The background air density gets enhanced by SAPS with the most prominent variation occurring around 19 MLT. There are density bulges appearing around the SAPS latitude. The electron density trough gets deepened and attains the minimum in the first orbit after the SAPS onset. The largest depletion can also be found around 19 MLT. Both the eastward and westward Hall currents (electrojets) get strengthened right after SAPS onset. The zonal wind peaks 2°–3° in latitudes equatorward of the eastward electrojet.