Temporal variability of nonlinear wave processes during sudden stratospheric warming of various types
K.A. Didenko1,2, A.V. Koval1, T.S. Ermakova1,3
1Saint Petersburg State University, St. Petersburg, Russia
2Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation, Russian Academy of Sciences, Moscow, Russia
3The Voeikov Main Geophysical Observatory, St Petersburg, Russia
Keywords: sudden stratospheric warming, stratospheric polar vortex, planetary wave, eddy potential enstrophy, wave activity
Abstract
Atmospheric waves on a planetary scale play the main role in the formation of the atmosphere regime, and a polar vortex forms in the stratosphere in winter. A striking example of the interannual variability of the stratospheric polar vortex caused by stationary planetary waves is sudden stratospheric warming (SSW). The internal dynamics of major sudden stratospheric warming accompanied by displacement and splitting of the stratospheric polar vortex (SPV) was studied based on the MERRA-2 reanalysis data from the point of view of explicitly calculating nonlinear interactions of planetary waves with each other and with the mean flow to identify similar trends in the formation of SSW of various types. In particular, it is shown that the formation of a SSW with SPV splitting is not always accompanied by dominant variations in the wave activity of stationary planetary wave with zonal wavenumber 2 (SPW2), but is determined by the maximum interactions of SPW2 with the mean flow. It was obtained that the wave-wave interactions during the generation of secondary stationary planetary wave with zonal wavenumber 1 (SPW1) are maximal 1-2 weeks before, and during the generation of secondary SPW2, 5-10 days before a SSW with SPV displacement. The results aimed at identifying predictors of SSW formation are important due to the fact that SSW significantly affects the entire middle atmosphere, ionosphere, as well as weather conditions in the troposphere and the formation of extreme weather events.
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