Dayside E-region strong neutral wind shear and its effect on F-region plasma irregularities

Vertical wind shears predominantly form sporadic E layers. Es-layer instability is one of the major sources of large-scale wave structures, which is essential for equatorial plasma bubbles to onset and develop. The global climatology of large neutral wind shears, derived from ICON MIGHTI data, exhibits a pronounced dependence on both season and latitude, with distinct behaviors observed between zonal and meridional wind shears. Large shears are a particularly common phenomenon during the summer season. In this study, we explored the potential role of these large E-region shears in the formation and structuring of plasma bubbles. Several events are chosen based on the availability of IVM-MIGHTI conjugate data when F-region irregularities coincide with large wind shears. These measurements are combined with TEC and vertical drift observations to distinguish the sources between TIDs and EPBs. Simulations of one-way coupled SAMI3 and GITM are conducted to enhance the physical understanding and interpretation of observations. Introducing observation-based artificial shears into GITM simulations, and using its neutral outputs for SAMI3, we compared simulations with and without shears. We found that shears effectively create a localized dense thin layer and lead to only minor conjugate variations in electron density (up to ~10%) and conductance. The configuration and location of these shears are crucial in creating a sufficient polarized electric field, and in turn, amplify/depress upwelling and development of EPBs.