Effects of Major Geomagnetic Storms on Total Electron Content near the Equatorial Ionization Anomaly (EIA) and Low Latitude Regions

Abstract

In this paper, weinvestigated the fluctuations in Total Electron Content (TEC) during major geomagnetic storms from 2012 to 2021, using the data from six IGS stations: GUAM, GUUG, IISC, DARW, KAT1, and ALIC. We studied the effect of six major geomagnetic storms on TEC, which occurred on 8 September 2017, 17 March 2015, 15 July2012, 8 May 2016, 7 October 2015, and 20 December 2015. These events showed substantial variations in TEC, with noticeable increasesfrom 2.4% to346%. We also used the global aTEC maps to demonstrate the spatial diversity of TEC enhancements. The analysis indicated that the most significant TEC variations occurred in equatorial and low-latitude regions.The stations located near the equator region responded earlier to the geomagnetic storms of 17 March 2015, 20 December 2015, 8 May 2016. Further, theionosphericeffects are found to be subsequently shifting toward low-latitude stations due to the equatorial electrodynamics and prompt penetration electric fields (PPEF). However,during the geomagnetic storm of15 July 2012 the low latitude stations responded earlierthan equatorial stations. The findings emphasize the crucial role of geomagnetic activity in driving changes in the ionosphere, which in turn affects global TEC levels.