Ionospheric response to the 26 August 2018 geomagnetic storm using GPS-TEC observations along 80° E and 120° E longitudes in the Asian sector

Abstract

This study investigates the response of equatorial and low latitude ionosphere during an intense geomagnetic storm of 26 August 2018 (Dst min = −206 nT) using the TEC observations from two chains of GPS stations along 80° E and 120° E longitudes in the Asian sector. These GPS networks include Waltair and four IGS stations (SGOC, IISC, HYDE and LCK4) along 80° E and five IGS stations (SHAO, TCMS, CKSV, PIMO and PGEN) along 120° E longitudes. The [O]/[N2] observations from GUVI have also been used for the present study. Large positive storm effect is observed in the day-time TEC for three consecutive days starting from main phase until the late recovery phases of the storm (26th to 28th August 2018). Significant difference has been observed in TEC response between 80° E and 120° E longitudes particularly during the recovery phase of the storm which is further confirmed by GIM derived TEC. The equatorial ionization anomaly (EIA) exhibit strong enhancement around the anomaly crests during the main phase of the storm. This enhancement in the EIA crest is also evidenced in GIM CODE TEC maps. The positive storm effect during the main and recovery phases is mainly attributed to the eastward prompt penetration electric fields in addition to strongly enhanced ratio of thermosphere neutral composition i.e. [O]/[N2], the results of which are presented in this paper.