Climatology of Thermospheric Winds in the Southern Polar Cap: Long-term Ground-based Observations from JBS-FPI

This study provides the first long-term ground-based climatological analysis of upper thermospheric winds (~250 km altitude) in the southern polar cap, using Fabry-Perot interferometer (FPI) observations at Jang Bogo station (JBS, 80°S magnetic latitude), Antarctica, from 2014 to 2022. The winds exhibit a pronounced diurnal variation, characterized by persistent anti-sunward flow across all magnetic local time (MLT) sectors, with westward winds in the dawn sector and eastward winds in the dusk sector, primarily driven by ion-neutral coupling. Seasonal and solar activity dependencies reveal stronger westward winds during equinoxes and enhanced wind magnitudes under high solar activity, resulting from increased ion-neutral collision frequencies and pressure gradients. Geomagnetic activity further modulates the wind patterns, intensifying wind speeds and enhancing duskward deviations, indicative of a strengthened dusk-side ionospheric convection cell. The influence of interplanetary magnetic field (IMF) orientation is also examined, showing that IMF Bz predominantly affects wind intensity, while IMF By governs directional asymmetry. These results provide observational evidence of IMF-driven wind responses in the southern polar cap and improve our understanding of high-latitude magnetosphere-ionosphere-thermosphere (MIT) coupling in the southern hemisphere.