Study of ionospheric response to an intense geomagnetic storm of 26 August 2018 over low latitudes and polar regions

During, the minimum phase of Solar Cycle 24, an intense geomagnetic storm occurred on August 26, 2018. This storm is significant not only because of its extremely high magnetic activity but also due to its great impact on the geo-magnetosphere. The aim of this paper is to distinguish the response of the equatorial/low latitude ionosphere to geomagnetic storms from those observed in the polar ionosphere. The ionospheric response to this storm has been investigated using 14 GPS receivers at the low latitudes and polar regions in the Asian and Antarctic sectors. Analysis of GPS-TEC data during the geomagnetic storm found both positive and negative storm effects over low and polar latitudes. The enhancement in VTEC data before the commencement of the geomagnetic storm is observed over all the stations at low latitude and polar regions, which is attributed to the pre-storm solar-induced events like CMEs, and proton events. Observed geomagnetic storm effects at different longitude sectors, whether it is positive or negative, are discussed using prompt penetration of electric field, disturbance dynamo electric field, neutral wind composition changes, and storm-induced wind lifting effects. During the recovery phase on 27–28, August the positive storm effect is noticed in daytime hours at equatorial/low latitude stations, whereas the negative storm effect as in the polar region.