Ionospheric Response to Intense Geomagnetic Storms of 17 March 2015 and 22 June 2015 over the East African region

Abstract

The variation of Total Electron Content (TEC) derived from seven International Global Navigation Satellite System (GNSS) stations (IGS) over the East African low latitude region for intense geomagnetic storms of 17 March 2015 and 22 June 2015 was investigated. The O/N2 maps were accessed from the GUVI website. Daily variation of Dst, IMF Bz, IEF Ey, and solar wind speed for the period was analyzed. The results showed during the storm of 17 March 2015 a positive storm effect was noticed over the station during the initial and main phase of the storm across the stations which was attributed to the prompt penetration of high–latitude electric fields to lower latitudes and the effect of Equatorial Ionization Anomaly (EIA) and negative storm effect which was attributed to the downward E × B drift and depletion of O/N2 over the East African region. During the storm of 22 June 2015, there was a positive storm effect during the recovery period across all the stations, which was also attributed to the prompt penetration of high–latitude electric fields to lower latitudes and the effect of EIA. The study also revealed that the storm impacts varied with local time and season, with greater effects during the equinox period, indicating that local time plays a role in the ionospheric response to geomagnetic storms.