Some Aspects of Victory Day 2024 Geomagnetic Storm Occurred on May 10–12, 2024, Using Satellite and Ground-Based Data

The presented work examines the extreme geomagnetic storm that occurred during May 10–12, 2024, following solar flares on May 8–9, 2024, hence named the Victory Day Storm. This event, marked as the most intense geomagnetic storm of the 21st century to date, caused significant disturbances not only in the auroral zone but also in the subauroral and mid-latitude ionosphere. Using data from satellites, ground-based ionosondes, Global Navigation Satellite System (GNSS) receivers, and all-sky cameras located in the Kaliningrad region, this research tracks how the coronal mass ejection from the Sun led to substantial changes in ionospheric plasma density, structure, and dynamics. Notably, auroras were observed in the subauroral and mid-latitudes, which is a rare phenomenon at these latitudes, providing valuable information on the ionospheric response to extreme geomagnetic activity. Swarm and DMSP satellite data identified polarization jet/SAID as U-shaped structures on ionograms, while Strong Thermal Emission Velocity Enhancements (STEVE) was observed by an all-sky camera along with increased Rate of Total Electron Content Index (ROTI). A diffuse aurora with a moving omega structure, as well as ray and corona auroral features, were observed, accompanied by a significant ROTI increase and enhanced scattering of the auroral Es layer on ionograms.