On the Different Quasi-2-Day Wave Behaviors during Sudden Stratospheric Warming Periods

Abstract

The temporal variations in the sudden stratospheric warming (SSW) events in the winter stratosphere always coincide with the quasi-2-day wave (Q2DW) in the summer mesosphere, and the impact of SSW on Q2DW is interesting but still a mystery. Major SSWs occurred in both 2006 and 2009, while the Q2DW activity was quite different. The Second Modern Era-Retrospective Analysis for Research and Applications (MERRA-2) reanalysis dataset was used to comparatively analyze these two major SSW events and elucidate the reasons for the different Q2DW behaviors. We noticed that the summer easterly jet shows a large interannual variability. We conclude that the summer mesospheric Q2DWs are modulated by the winter SSW, whereas the modulation process is also affected by the interannual variability of the summer easterly flow itself. The effects of the SSW on the Q2DWs may differ from year to year due to the variability of the summer easterly flow itself, resulting in different anomalous Q2DW behavior. This conclusion may also be true for the interannual variability of other phenomena during the SSW period.

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

“…SSWs are very common in the northern hemisphere, where PWs are enhanced by the interaction between sea and land; in the southern hemisphere, where middle and high latitudes are mostly oceanic, lack of sea−land interactions results in many fewer PWs and SSWs. The rapid changes of temperature and wind in the upper and middle atmosphere of the winter hemisphere that characterize an SSW have significant impact on the atmospheric circulation (Tang L et al, 2023). During SSWs, the temperature of the polar stratosphere increases rapidly -within a few days, accompanied by weakenings of the polar vortex and easterly winds.…”