The Response of African Equatorial/Low‐Latitude Ionosphere to 2015 St. Patrick's Day Geomagnetic Storm. Issue 6 (4th June 2018) - Amaechi, P. O.
Abstract: Total electron content (TEC) has been used to study the response of the African equatorial/low‐latitude ionosphere to the 17 March 2015 intense storm. Daily variations of symmetric H index, z component of interplanetary magnetic field, polar cap index, and H component of the Earth's magnetic field were analyzed along with TEC obtained from stations classified into western (11.53°E to 5.24°W) and eastern (25.00°E to 40.20°E) sectors. Storm time behavior of TEC was compared with the mean TEC of quiet days. TEC was enhanced over both sectors at the beginning of the storm while it reduced after the main phase as a result of prompt penetration of electric field and disturbance dynamo electric field (DDEF), respectively. The magnetic effect of the disturbed ionospheric electric current showed oscillations and minima in response to prompt penetration of electric field, which further enhanced the equatorial ionization anomaly. The effect of DDEF estimated from the ionospheric disturbance dynamo manifested in the form of decrease in the amplitude of the horizontal component of the Earth magnetic field ( H ) several hours after the beginning of the disturbance and during the recovery phase. Consequently, ionospheric irregularities were suppressed over all stations in both sectors on 17 and 18 March due to westward DDEF. On the 19 March, however, there was a difference in the pattern of irregularities over both sectors. Key Points: TEC was enhanced and the south crest of the EIA shifted from 10 to 17 degree during the main phase of the Saint Patrick's storm, March 2015 Irregularities were suppressed during the main phase and during the recovery phase on the 18th over both eastern and western sector PPEF and DDEF modulated the behaviour of TEC/ irregularities. On 19 March a difference in irregularities pattern occurred over both sectors