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

During the sudden stratospheric warming (SSW) event in 2013, we investigated the American low latitude around 75°W. We used 12 Global Positioning System (GPS) receivers, a pair of magnetometers, and the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite airglow instrument to unveil the total electron content (TEC), inferred vertical drift, and the changes in the neutral composition, respectively. A major SSW characterized the 2013 SSW event with the main phase (7–27 January 2013) overlapped by a minor geomagnetic storm (17 January 2013). The late morning inferred downward‐directed E X B drift did not support the varying equatorial ionization anomaly (EIA) signature during the SSW onset (7 January 2013). The mid‐January (15–16 January 2013) witnessed enhancement in the varying inferred upward‐directed E X B drift at both hemispheres. On 17 January 2013, there were reductions in the varying inferred upward‐directed E X B drift at both hemispheres. Generally, the SSW effect on TEC around 15–16 January 2013 is more pronounced than the SSW onset. During the mid‐January (15–16 January 2013), the higher northern EIA crests are facilitated majorly by the SSW compared to the photo‐ionization that primarily enabled the southern crests. On 17 January 2013, the combined effect of photo‐ionization and SSW contribution was majorly responsible for the slight reduction in the northern crest. In the southern hemisphere, photo‐ionization played the lead role as the SSW, and the minor geomagnetic storm roles are secondary in enhancing the southern crest. Plain Language Summary: The vertical coupling between the lower atmosphere and the ionosphere is evident during large‐scale metrological events called sudden stratospheric warming (SSW). This event occurred during the northern wintertime and was characterized by the sudden breakdown of the stratospheric polar vortex due to the enhanced amplitude of the upward propagating planetary waves in the stratosphere. We investigated the American low‐latitude ionosphere during 2013 SSW and when overlapped by a minor geomagnetic storm using total electron content (TEC) data from Global Positioning System receivers. A pair of magnetometers and the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite airglow instrument revealing the varying vertical inferred E X B drift and global changes in the neutral composition, O/N2 ratio are also used. The late morning inferred downward‐directed E X B drift during the SSW onset did not support the varying EIA signature. The re‐location of the northern equatorial ionization anomaly (EIA) crest during mid‐January was associated with an enhancement in the variable semidiurnal late morning inferred upward‐directed drift due to intensified SSW conditions. The combined effect of the photo‐ionization and SSW caused a slight reduction of the TEC at the northern crest during the ongoing SSW modulated by a minor storm. Key Points: The late morning inferred download‐directed E X B drift did not support the varying equatorial ionization anomaly signature during the sudden stratospheric warming (SSW) onsetThe higher SSW effect during the mid‐January was seen in the enhancement of the late morning inferred E X B drift at both hemispheresThe slight reduction in the northern crest during the minor storm was due primarily to photo‐ionization and SSW's combined effect [ABSTRACT FROM AUTHOR]