Equatorial ionization anomaly variability over the Brazilian region during boreal sudden stratospheric warming events

Abstract

AbstractThis study refers to the connection between the stratosphere and ionosphere, investigating, specifically, the behavior of the equatorial ionization anomaly (EIA) and ionospheric effects over the Brazilian region during sudden stratospheric warming (SSW) events. We studied three major warmings that occurred in the Northern Hemisphere winter 2007–2008, 2008–2009, and 2009–2010 and a minor warming that occurred in 2010–2011. The solar activity was low for the first two cases and relatively moderate for the last two. In this study the EIA behavior was investigated using the ΔTEC (total electron content) parameter, which expresses the EIA relative intensity for the Brazilian sector. The results for the Brazilian region show, mainly after SSW temperature peak, an increase in the EIA intensity in the morning, followed by a decrease in the afternoon. As identified through ΔTEC signatures and consistently confirmed through wavelet power spectra analysis, this semidiurnal behavior is preserved for a number of days equal to the polar region thermal stabilization phase and it is very similar to the results obtained in pioneer studies in the Peruvian sector, in which TEC data was also used. In some cases the TEC negative variation is stronger than the positive, being noticeably more intense around the prereversal enhancement time, when the EIA is strongly suppressed in the Brazilian sector.