The Ionospheric Response to the 2013 SSW Event Over the Asian‐Australian Sector

Abstract

This study investigates the response of the Asian‐Australian low‐latitude ionosphere to the 2013 Sudden Stratospheric Warming (SSW) event. The equatorial ionization anomaly (EIA) structures were built from the latitudinal distribution of Total Electron Content (TEC) measured from 10 Global Positioning System (GPS) receivers along 115°E in the Asian‐Australian sector. A pair of magnetometers and NASA Thermosphere‐Ionosphere‐Mesosphere Energetics and Dynamics (TIMED) satellite airglow instrument were also employed to measure the equatorial electrojet (EEJ) strength (inferred EXB drift) and to unveil the changes in the neutral thermospheric O/N2 ratio during the SSW event, respectively.The relocation of the northern crests to higher latitudes during the SSW compared to the non‐SSW periods was mainly attributed to the combined effect of enhanced magnetometer‐inferred upward‐directed E X B drift and increasing solar flux. The local time shift in the thermospheric O/N2 ratio, a slight enhancement in the magnitude of the semi‐diurnal magnetometer‐inferred upward‐directed E X B drift, and changes in solar flux were primarily responsible for the hemispheric TEC enhancement during mid‐January compared to SSW onset. Additionally, the photo‐ionization effect due to increasing solar flux further enhances the TEC magnitude during the relaxing phase. On the other hand, the strong thermospheric equatorward wind played a crucial role in moving the plasma to lower latitudes during the zonal wind transition phases. A moderate geomagnetic storm of 17 January 2013 did not perturb the Asian‐Australian ionosphere. However, on 18 January 2013, the storm had a significant impact and greatly diminished the effect of the SSW.