Ion-Neutral Coupling in the Southern Polar Cap by First Simultaneous Observations of Ion Drifts and Neutral Winds at Jang Bogo Station (JBS), Antarctica

Simultaneous observations of ion drifts and neutral winds have been conducted at Jang Bogo Station (JBS), Antarctica since 2017 using a Dynasonde and a Fabry-Perot Interferometer, respectively. This study presents the results of a comparison between these two measurements to investigate the impacts of ion drifts on neutral winds in the Southern polar cap during winter. The results observationally demonstrate that neutral winds are largely weaker than ion drifts, suggesting that the neutral winds rarely reach a statistical steady-state. However, thermosphere-ionosphere-electrodynamics general circulation model simulations show the opposite trend, significantly underestimating ion drifts. Neutral winds are also found to have different characteristics depending on the magnetic local time sectors, being weaker on the dayside than on the nightside of the polar cap, which is possibly explained if the previous histories of the neutrals before being observed are considered. Additionally, changes in neutral winds due to ion drag are more noticeable in the duskside than in the dawnside due to differences in collision frequency, which is primarily dependent on the diurnal variations of ionospheric density at JBS.