Relationship between the Interhemispheric Asymmetry of the post-sunset Equatorial Ionization Anomaly and Scintillation Occurrence During Sudden Stratospheric Warming Events

Sudden Stratospheric Warming (SSW) represents large and rapid temperature increases in the winter polar stratosphere, along with weakening or reversal of eastward zonal winds caused by breaking of the upward-propagating planetary-scale waves that disrupt the polar vortex. During these events, substantial changes of the post-sunset Equatorial Ionization Anomaly (EIA) are frequently observed. Specifically, case studies indicate that stronger scintillations in the equatorial region tend to occur during the periods when significant interhemispheric asymmetries (IHAs) in the post-sunset EIA are observed. However, it remains unclear whether such a positive correlation between the IHA of the post-sunset EIA and scintillation holds statistically. In this study, we utilize the ground-based Global Navigation Satellite System (GNSS) Total Electron Content (TEC) measurements in the American sector, along with the S4 scintillation measurements from the Low-Latitude Ionospheric Sensor Network (LISN), to explore the correlation between the IHA of the post-sunset EIA and scintillation during several major and minor SSW events. More specifically, we are investigating the SSW events of 2009 (major), 2019 (Northern and Southern hemisphere event) and 2021 (major). If such a causal relationship has been validated by the observation, we will further utilize the Specific Dynamics version of Whole Atmosphere Community Climate Model with thermosphere-ionosphere extension (SD-WACCMX) to investigate whether the E×B plasma drift and meridional wind, which are key drivers of equatorial plasma bubble generation, exhibit consistent differences between the period when the post-sunset EIA show significant IHAs and the period when it does not. This study aims to advance understanding of the cause of significant IHAs in the post-sunset EIA and the relationship between the IHA of the post-sunset EIA and the scintillation. These results will contribute to the development of more effective mitigation strategies to safeguard communication and navigation systems from adverse space weather impacts.