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Description
This study investigates the response of the ionosphere–thermosphere system over Europe during the severe geomagnetic storm of May 2024. Between May 7 and 11, multiple X-class solar flares and at least five Earth-directed coronal mass ejections (CMEs) were observed. The initial CME impacted Earth at 12:30 UTC on May 10, triggering a geomagnetic disturbance that led to a pronounced negative ionospheric storm across mid-latitude European stations. Data gaps recorded on May 11 were attributed to the occurrence of the "G condition," characterized by the electron density at the F2 layer maximum equaling or falling below that of the F1 layer.
Thermospheric parameters derived using the THERION method revealed a 60% increase in neutral atomic oxygen density ([O]) at 300 km altitude and a ~50% rise in thermospheric temperature. Conversely, column-integrated O concentration decreased by approximately 30%. Enhanced equatorward winds were detected between May 10 and 13. Comparative analysis across different longitudinal sectors confirmed significant regional variability, highlighting the dynamic behavior of the coupled ionosphere–thermosphere system during extreme geomagnetic conditions.
