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

Xiaohua Mo,Donghe Zhang

doi:10.5194/angeo-38-9-2020

Abstract

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.

Highlights

Sudden stratospheric warming (SSW) is large-scale meteorological process in the polar stratosphere which is characterized by a rapid rise in temperatures and a deceleration/reversal in the zonal-mean flows (Scherhag, 1952)
We present the first observational evidence of quasi-10 d oscillation in the equatorial ionization anomaly (EIA) region during the 2002 Southern Hemisphere (SH) SSW which has not been reported during Northern Hemisphere (NH) SSWs, based on the location of EIA crests derived from global positioning system (GPS) station observations, the total electron content (TEC) obtained by the International GNSS Service (IGS) global ionospheric TEC map (GIMs), and the EEJ estimated by the geomagnetic field in the Asian sector
Using the location and TEC of the EIA crests derived from GPS station observations and GIMs, we found a quasi-10 d periodic variability in the northern and southern EIA region in the Asian sector during the SH SSW of 2002

Summary

Introduction

Sudden stratospheric warming (SSW) is large-scale meteorological process in the polar stratosphere which is characterized by a rapid rise in temperatures and a deceleration/reversal in the zonal-mean flows (Scherhag, 1952). The main processes of SSWs occur in the polar middle atmosphere, its effects on the ionosphere have been observed in significant changes of the equatorial electrojet (EEJ), vertical plasma drift, and equatorial ionization anomaly (EIA) (Vineeth et al, 2007; Chau et al, 2009; Goncharenko et al, 2010; Pancheva and Mukhtarov, 2011; Jin et al, 2012). A great deal of research has been focused on the variation of the low-latitude ionosphere during SSW in the NH, and the quasi-16 d periodic disturbance and the lunar tide characteristics have been found in some ionospheric parameters, for example, EEJ, vertical plasma drifts and ionospheric electron density (Vineeth et al, 2007; Chau et al, 2009; Pedatella and Forbes, 2009; Goncharenko et al, 2010). Some researchers considered that this kind of quasi-16 d periodic variations is related to the enhanced planetary wave during the SSW period

Results

Discussion

Conclusion