Storm Time Effects on Latitudinal Distribution of Ionospheric TEC in the American and Asian‐Australian Sectors: August 25–26, 2018 Geomagnetic Storm.

On the dayside of August 25–26, 2018 (main phase, MP of the storm), we unveiled the storm time effects on the latitudinal distribution of ionospheric total electron content (TEC). We used 17 and 19 Global Positioning System receivers in American and Asian‐Australian sectors, respectively. Also, we employed a pair of magnetometers in each sector to unveil storm time effects on vertical E × B upward directed inferred drift velocity in the F region ionosphere. Also used is NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite airglow instrument to investigate storm time changes in neutral composition, O/N2 ratio. In this investigation, we corrected the latitudinal offset found in the works of Younas et al. (2020, https://doi.org/10.1029/2020JA027981). Interestingly, we observed that a double‐humped increase (DHI) seen at a middle latitude station (MGUE, ∼22°S) after the MP on the dayside in American sector (Younas et al., 2020, https://doi.org/10.1029/2020JA027981) did straddle ∼23.58°N and ∼22°S. On August 25, 2018, storm commencement was evident in Sym‐H (∼−8 nT) around 18:00 UT. It later became intensified (∼−174 nT) on August 26 around 08:00 UT. During storm's MP (after the MP), fountain effect operation was significantly enhanced (inhibited) in Asian‐Australian (American) sector. Middle latitude TEC during MP got reduced in American sector (13:00 LT–15:40 LT) compared to those seen in Asian‐Australian sector (13:00 LT–15:40 LT). The northern equatorial peak (∼25 TECU) seen at IHYO (14:00 LT) after MP in the American sector is higher when compared with that (∼21 TECU) seen at PPPC (11:40 LT) during MP in Asian‐Australian sector. Plain Language Summary: The double‐humped increase (DHI) that was reported at a single location in a middle latitude (Younas et al. 2020, https://doi.org/10.1029/2020JA027981) did straddle the American middle, low and equatorial ionosphere. We suspected that a surge in an ongoing storm‐time equatorward neutral wind that was proportional to UcosI around 17:00 UT–18:00 UT is responsible for the DHI after the main phase. A clear longitudinal difference in ionization production and chemical loss at all latitudes between the American and Asian‐Australian sector was observed Key Points: A double‐humped increase that have been reported at middle latitude station on the dayside of the main phase in American sector straddled ∼23.580°N and ∼220°SFountain effect operation in the low latitudes was significantly enhanced in Asian‐Australian sectorFountain effect operation in the low latitudes was inhibited in American sector [ABSTRACT FROM AUTHOR]