Longitudinal Variability of Pre-midnight Equatorial Plasma Bubbles Under Geomagnetic Activity: The role of Thermospheric Winds

Equatorial plasma bubbles (EPBs) present significant challenges to trans-ionospheric radio communications, particularly affecting Global Navigation Satellite System (GNSS) signals, which can lead to signal degradation and disruptions in communication and navigation. By reducing the number of usable GNSS satellites for accurate positioning, EPB occurrences underscore the importance of evaluating and predicting them in the development of space systems. One critical factor that remains elusive is the influence of geomagnetic activity on EPBs. This study aims to address this gap by performing a superposed epoch analysis on key parameters: geomagnetic indices, zonal and meridional neutral winds, and the $\sigma$ index, which serves as an indicator of EPB presence. Using data collected by the Ionospheric Connection Explorer (ICON) satellite from 2020 to 2022, between 18:00 and 23:00 SLT, our analysis reveals regional differences in EPB behavior. In South America, EPB occurrences are suppressed during the decline of geomagnetic activity, while over Africa, EPB occurrence increases during periods of heightened geomagnetic activity. Additionally, we observe a shift in zonal winds toward the west near the peak of geomagnetic disturbances. These findings contribute to a deeper understanding of EPB dynamics and highlight the regional variability in their response to geomagnetic disturbed conditions.