Contrasting Latitudinal/Longitudinal Response of Equatorial Ionization Anomaly (EIA) Around ± 75 ° $\mathbf{75}\mathbf{{}^{\circ}}$ Longitude Sectors During the 23–24 April 2023 Geomagnetic Storm

Abstract

We present hitherto unreported contrasting latitudinal/longitudinal features of Equatorial Ionization Anomaly (EIA) during the geomagnetic storm of 23–24 April 2023, using Total Electron Content measurements around $\pm 75°$ longitude sectors. Besides the change in the strength of EIA due to the storm-time Prompt Penetration and Disturbance Dynamo electric fields, a longitudinally elongated EIA over the Indian sector is observed along with a latitudinally expanded EIA over the American longitude sector during this storm. Early and late appearances of EIA are also observed, particularly over the American sector. Based on neutral wind data of Thermosphere Ionosphere Electrodynamic General Circulation Model, we suggest that the storm-time neutral wind dynamics over a given longitude sector have worked in tandem with storm-time electric fields to generate these contrasting EIA features. These results hold important clues for understanding the low-latitude ionosphere during space weather events under the combined effects of electric fields and neutral winds.