African and American Equatorial Ionization Anomaly (EIA) Responses to 2013 SSW Event

Abstract

This study investigates the responses of the African and American Equatorial Ionization Anomaly (EIA) regions to 2013 Sudden Stratospheric Warming (SSW) event. The Total Electron Content (TEC) data obtained from chains of Global Positioning System receivers within ±40° geomagnetic latitudes in the African and American sectors were used to construct the EIA structures for both longitudinal sectors. The responses of the EIA structures, constructed from the TEC, ΔTEC, and ionospheric irregularities data to the 2013 SSW event were investigated. During the SSW peak phase, EIA structures in both longitudinal sectors responded significantly, with the pole‐ward flow of plasma from the equator to higher crests' locations (strengthening of the EIA). Furthermore, a clear asymmetry in plasma distribution in the northern and southern crests of the EIA was observed. Generally, for the entire data span, TEC enhancements and ionospheric irregularities occurrences during SSW were more in the American sector than the African sector. The geomagnetic activity of 17 January 2013 caused negative TEC response in the African sector and positive TEC response in the American sector. Moderate storm‐induced TEC enhancements were generally lower than SSW‐induced TEC enhancements. Furthermore, solar flux‐induced TEC of 10 January 2013 was lesser than the SSW‐induced TEC of 15–16 January 2013.

Response of the American equatorial ionization anomaly to 2016 Arctic sudden stratospheric warming events

“…The remaining storms (1 January, 18 February, 16 March, and 20 March) investigated (Figure 6) showed a negative EIA TEC signature. These negative EIA TEC features are contrary to the recent report of the positive ionospheric response in the American sector for the 2013 SSW event (Idolor et al, 2022). Idolor et al (2022) reported that the impact of the PPEF on the ionosphere just around sunset enhances the eastward electric field via the vertical E X B drift leading to the enhancement of the EIA TEC profile (Tsurutani et al, 2008).…”

“…Modeling results using the thermosphereionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM) of the vertical drifts for the 2013 SSW event showed a significant increase in daytime vertical drift of ~100% associated with the moderate geomagnetic storm occurrence for the American sector (Maute et al, 2015). A similar report of positive ionospheric response in the TEC was presented in the American sector and negative ionospheric TEC response in the African sector associated with the overlap of the moderate geomagnetic storm with the 2013 SSW event (Idolor et al, 2022). Several studies have also shown an increase in TEC enhancement at the equatorial ionization anomaly (EIA) crest regions during some of the SSW events in the American sector (Goncharenko et al, 2013;Paes et al, 2014), while the EIA TEC suppression have been reported in the Brazilian sector (De Jesus et al, 2017b;Vieira et al, 2017).…”

“…where ΔTEC overlap is the TEC variations associated with the overlap of the SSW and geomagnetic storm, and ΔTEC ssw gives the TEC variations, resulting solely from the underlying SSW variations. Similar methodology has been adopted to isolate the moderate geomagnetic storm effects overlapping with the SSW event on 17 January 2013 (Idolor et al, 2022).…”

“…The EEJ current is given by the following expression: where H HUA is the solar quiet (Sq) current computed for Huancayo and H PLU is the Sq current computed for the Piura magnetometer stations, respectively, while the estimated inferred vertical drift of the ΔH horizontal current was obtained from a mathematical relationship using the vertical drift model ). Anderson's quantitative mathematical formulation obtained from the neural regression technique is given by the following expression (Anderson et al, 2002;Yizengaw et al, 2014;Kassamba et al, 2020;Idolor et al, 2021;Idolor et al, 2022).…”

“…De Jesus et al (2017a) reported a nighttime enhancement in the TEC during the 2014 major SSW event in March. Both the SSW events (2013 and 2014) were also reported to overlap with the occurrence of geomagnetic storms (Idolor et al, 2021(Idolor et al, , 2022. Modeling results using the thermosphereionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM) of the vertical drifts for the 2013 SSW event showed a significant increase in daytime vertical drift of ~100% associated with the moderate geomagnetic storm occurrence for the American sector (Maute et al, 2015).…”