Год издания: 2026

We investigated global ionospheric effects of a geomagnetic 24 March 2024 storm (minimum SYM-H = 174 nT) classified as G4. At the time of its onset, this event ranked as the fifth most intense storm in solar cycle 25. We utilized data from vertical incidence ionosondes, a network of global navigation satellite system (GNSS) receivers, and global ionospheric maps of Total Electron Content (TEC). To interpretate and examine magnetic storm influence on radiowave propagation we applied observations from ISTP SB RAS instruments located in Eastern Siberia. Based on data from global ionospheric monitoring networks (GIRO, GIM TEC), we studied global ionospheric response to geomagnetic disturbances. During the main and recovery phases of the geomagnetic storm, elevated ionization was observed in the equatorial anomaly crests: peak values exceeded those during geomagnetically quiet days by over 30 TECU. Four vertical incidence sounding stations within the Global Ionospheric Radio Observatory (GIRO network) recorded a complete absorption of HF signals lasting for 6 h at high latitudes, while oblique paths in the East-Siberian sector showed a total blocking of HF radio paths lasting 10 h. Errors in GNSS positioning using the kinematic precise point positioning mode doubled at high and middle latitudes the main effect was seen in Alaska, Europe and South America. In Irkutsk, the drop in electron density amounted to 75% at the F2 layer maximum. Within few hours, the neutral atmospheres temperature rose from 1000 K to 1500 K at an altitude of 250 km; the southward meridional wind intensified rising from 20 m/s to 160 m/s. The geomagnetic storm was accompanied by a substantial (up to 12%) Forbush decrease in cosmic ray intensity.