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

Abstract

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.

Ionospheric Disturbances and Irregularities During the 25–26 August 2018 Geomagnetic Storm

“…Therefore, we conclude that the observed effects in the Ne and VEC were due to the storm-time reinforcement of the EIA, also known as the dayside super-fountain effect (SFE, e.g., Astafyeva, 2009;Mannucci et al, 2005;Tsurutani et al, 2004). Our conclusions are in line with results presented by Bolaji et al (2021), who showed an extreme increase in the intensity of the horizontal magnetic field, and, consequently, the enhancement of the E x B drift in this region during this period of time.…”

“…in the magnetosphere, ionosphere, and thermosphere (e.g., Astafyeva et al, 2020;Blagoveshchensky & Sergeeva, 2019;Bolaji et al, 2021;Piersanti et al, 2020;Spogli et al, 2021;Younas et al, 2020). Blagoveshchensky and Sergeeva (2019) studied ionospheric response over Europe and observed positive disturbance at mid and low latitudes during the main phase.…”

Response of the Ionospheric TEC to SSW and Associated Geomagnetic Storm Over the American Low Latitudinal Sector

“…Therefore, a poleward plasma flow, which the eastward electric field can trigger, is rule‐out in this context. To the best of our understanding, simulation and experimental investigations during geomagnetic conditions (Balan et al., 2009; Bolaji et al., 2021) have shown that the daytime westward electric field inhibited EIA formation and supported the formation of an equatorial peak. Hence, on 7 January 2013, the combined effects of the varying solar flux (photo‐ionization production), SSW‐time neutral wind and SSW‐time thermospheric neutral composition O/N 2 ratio can be responsible for the EIA formation and its enhancement at the northern (LPUC) compared to the southern (IACR) crest.…”

“…This is attributed to different large‐scale physical processes like changes in the storm‐time neutral atmospheric composition, the prompt penetration of electric field (PPEF), the ionospheric disturbance dynamo electric field (DDEF), solar heating, and thermospheric winds (Blanc & Richmond, 1980; Fuller‐Rowell et al., 1994, 1996; Gonzales et al., 1979; Nishida, 1968; Vasyliunas, 1970, 1972). It is important to note that the varying storm‐time equatorward wind and PPEF in the low latitudes that enhanced the EIA features (Tsurutani et al., 2008) and modulated it to an equatorial peak (Bolaji et al., 2021) can cause a more complex variability of the equatorial and low‐latitude electrodynamics (Venkatesh et al., 2017).…”

A Method to Mitigate the Effects of Strong Geomagnetic Storm on GNSS Precise Point Positioning

“…Next, we further present positioning results of two PPP schemes for another strong storm occurred on 26 August 2018. For this storm, the minimum value of $$\text{Dst}$$ index is −174 nT, resulting in ionospheric disturbances detected by both space‐ and ground‐based sensors (Bolaji et al., 2021; Yang et al., 2020). Using 379 IGS stations data on 26 August 2018, Figure 9 presents RMS values of two PPP schemes in the horizontal and vertical components, respectively.…”