Analysis of gravity wave activity during stratospheric sudden warmings in the northern hemisphere

Abstract

Due to the significant changes they bring to high latitude stratospheric temperature and wind, stratospheric sudden warmings (SSWs) can have an impact on the propagation and energy distribution of gravity waves (GWs). The variation characteristics of GWs during SSWs have always been an important issue. Using temperature data from January to March in 2014−2016, provided by the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) mission, we have analyzed global GW activity at 15−40 km in the Northern Hemisphere during SSW events. During the SSWs that we studied, the stratospheric temperature rose in one or two longitudinal regions in the Northern Hemisphere; the areas affected extended to the east of 90°W. During these SSWs, the potential energy density (\begin{document}$ {E}_{p} $\end{document}) of GWs expanded and covered a larger range of longitude and altitude, exhibiting an eastward and downward extension. The \begin{document}$ {E}_{p} $\end{document} usually increased, while partially filtered by the eastward zonal winds. When zonal winds weakened or turned westward, \begin{document}$ {E}_{p} $\end{document} began to strengthen. After SSWs, the \begin{document}$ {E}_{p} $\end{document} usually decreased. These observations can serve as a reference for analyzing the interaction mechanism between SSWs and GWs in future work.

Keywords

• stratospheric sudden warming
• gravity wave
• wind filter