Climatology of Thermospheric Winds over the Southern Polar Cap from JBS-FPI Observations

Abstract This study presents the results from a climatological analysis of thermospheric winds (~ 250 km altitude) in the southern polar cap, based on the first long-sterm ground-based Fabry–Perot Interferometer (FPI) observations at Jang Bogo station (JBS; 80°S geomagnetic latitude), Antarctica, during 2014 − 2022. The winds exhibit pronounced diurnal variations, characterized by persistent anti-sunward flow across all magnetic local time sectors with a slight duskward tilt, primarily driven by ion drag in combination with day-to-night pressure gradients. The seasonal and solar activity dependencies show enhanced wind magnitudes during equinoxes and under high solar activity, likely reflecting stronger ion drag from increased ionospheric densities. The wind patterns are further modulated by increasing geomagnetic activity, which intensifies wind speeds and enhances the duskward tilts, associated with the strengthening of the dusk-side ionospheric convection cell. The orientation of the interplanetary magnetic field (IMF) also influences wind behaviors: a negative IMF Bz component increases wind magnitudes, while the IMF By component induces directional asymmetry by modulating ionospheric convection. These results offer new ground-based constraints on thermospheric wind circulation in the southern polar cap and its possible mechanisms over nearly a solar cycle. Graphical Abstract: