Examining the effects of vertical shears of zonal plasma drift and neutral wind on the instability of the postsunset equatorial ionosphere

Vertical shears of zonal plasma drift and neutral wind have been observed to occur frequently during postsunset hours at the equatorial ionosphere F-region bottom (England et al., 2022; Mathew & Prabhakaran Nayar, 2012). Several previous numerical studies (Guzdar et al., 1982; Sekar et al., 2012; Sekar & Kelley, 1998) reported that vertical shear of zonal plasma drift can reduce the growth rate of the Rayleigh-Taylor instability in the ionosphere and lead to the generation of long-lived bottomside equatorial plasma bubbles. Even though, equatorial plasma bubbles can be seeded by the vertical shear-associated waves and develop to upper ionosphere with the aid of other factors (Hysell et al., 2005, 2006). In this study, we intend to investigate the impacts of the vertical shears from different aspects, including strength, altitude, and local time, on the stability or instability of the ionosphere due to varying solar wind parameters. The growth rates of Rayleigh-Taylor instability calculated using the outputs of the coupled Whole Atmosphere Model and Ionosphere Plasma Electrodynamics model (WAM-IPE) under several different solar wind conditions and fixed lower atmospheric conditions are to be compared in detail. Comparative analysis with observational experiments will also be included. This study will not only provide some physical insights into the electrodynamics of the post-sunset equatorial ionosphere but also suggest some potential improvements to the model.