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Quasi-10 d wave modulation of an equatorial ionization anomaly during the Southern Hemisphere stratospheric warming of 2002

Abstract. The present paper studies the perturbations in an equatorial ionization anomaly
(EIA) region during the Southern Hemisphere (SH) sudden stratospheric
warming (SSW) of 2002, using the location of EIA crests derived from global
positioning system (GPS) station observations, the total electron content
(TEC) obtained by the International GNSS (global navigation satellite system) Service (IGS) global ionospheric TEC
map (GIMs) and the equatorial electrojet (EEJ) estimated by the geomagnetic
field in the Asian sector. The results indicate the existence of an obvious
quasi-10 d periodic oscillation in the location and TEC of the northern and
southern EIA crest. An eastward phase progression of the quasi-10 d wave
producing the SH SSW of 2002 is also identified in polar stratospheric
temperature. Previous studies have shown that a strong quasi-10 d
planetary wave with zonal wave numbers s=1 extended from the lower
stratosphere to the mesosphere and lower thermosphere during the SH SSW of 2002
(Palo et al., 2005). Moreover, the EEJ driven by the equatorial zonal electric
field exhibits quasi-10 d oscillation, suggesting the enhanced
quasi-10 d planetary wave associated with SSW penetrates into the
ionosphere E region and produces oscillation in the EIA region through
modulating the E-region electric fields. Our results reveal some newer
features of ionospheric variation that have not been reported during
Northern Hemisphere (NH) SSWs.