Remarkable changes in F region winds and plasma drifts during the stratospheric QBO disruption of 2019–2020

Analysis of the thermospheric wind and plasma drift data acquired respectively by the Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) and Ion Velocity Meter (IVM) onboard Ionospheric Connection Explorer (ICON) satellite reveals remarkable changes during the disruption of the stratospheric quasi-biennial oscillation (QBO) due to high planetary wave activity in December 2019-January 2020. The thermospheric winds, in particular, are found to be unusually equatorward over the dip equator and northern geomagnetic low latitudes. Moreover, the plasma drifts are upward over the dip equator during midnight hours . Besides, the plasma drift exhibits a clear semi-diurnal variation. It is suggested to be due to the decrease in the diurnal tidal amplitude as a result of the non-linear interaction between the diurnal tide and the planetary waves. The relative increase of semi-diurnal tide may have imposed semi-diurnal variation in the meridional winds which could turn equatorward around midnight hours. The equatorward winds can increase the growth rate of the Rayleigh-Taylor instability to generate delayed F-region irregularities around midnight hours.