Responses of the daytime low and equatorial ionosphere and thermosphere over the Indian region during the geomagnetic storm of April 2023

The ionosonde observations at the dip equatorial station, Trivandrum (8.52°N, 77°E, dip lat. = 1.96°N), are found to have unusually high F2 peak plasma density (foF2), with three maxima during the daytime on April 24. The Total Electron Content (TEC) observations from different latitudes showed enhancements temporally progressing from north to south.

These features are identified as Traveling Ionospheric Disturbances (TIDs) with speeds ∼400 to 750 m/s. Two major enhancements in TEC observed over Trivandrum were concurrent to the first and third maxima in foF2. Simulations of meridional wind and temperature for this storm were carried out using the Thermosphere–Ionosphere–Electrodynamics General Circulation Model (TIEGCM) that was driven with high‐latitude inputs derived from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) technique.