Observations of aurora with combined C-band Sentinel-1 and multi-sensor data: A case study during the 11 May 2024 super geomagnetic storm

Abstract

Synthetic Aperture Radar (SAR) provides all-weather, day and night operation with high spatial resolution, demonstrating potential in retrieving small-scale ionospheric disturbances. However, its capability for detecting auroral particle precipitation remains largely unexplored. This study investigates the impact of auroral interference on dual-polarization C-band Sentinel-1 SAR imagery over Europe and demonstrates that both VV and VH polarization channels can be employed to retrieve the ionospheric Total Electron Content (TEC) variations associated with auroral activity. Using the super geomagnetic storm that occurred on 11 May 2024 as a case study, the interferograms reveal two phase enhancement regions extending southeastward and northeastward, consistent with two auroral activity events recorded by Special Sensor Ultraviolet Spectrographic Imager (SSUSI) observations. Combined with coordinated observations from multiple satellites including Swarm, the Defense Meteorological Satellite Program (DMSP), and Gravity Recovery and Climate Experiment Follow-On (GRACE-FO), our study shows that during a geomagnetic storm with solar wind velocity reaching approximately 800 km s−1, the auroral structures exhibited breakup and dynamic evolution characterized by equatorward expansion. Our findings demonstrate that Sentinel-1 has the potential to detect and monitor ionospheric fine-scale structure variations caused by auroral particle precipitation, serving as a valuable complement to existing space-based observation methods and could help build a comprehensive auroral activity monitoring system with other space observation platforms.