Southern Hemisphere Response to the Secondary Planetary Waves Generated During the Arctic Sudden Stratospheric Final Warmings: Influence of the Quasi‐Biennial Oscillation. Issue 24 (14th December 2022)

• Record Type: Journal Article
• Authors: Qin, Yusong; Gu, Sheng‐Yang; Dou, Xiankang; Teng, Chen‐Ke‐Min; Yang, Zhenlin; Sun, Ruidi
• Is Part Of: Journal of geophysical research. Volume 127:Issue 24(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-12-14
• Subjects: sudden stratospheric final warming -- secondary planetary wave -- quasi‐biennial oscillation -- interhemispheric coupling -- residual circulation -- spring transition; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2022JD037730
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: Based on the Modern‐Era Retrospective analysis for Research and Applications version 2 reanalysis and Aura Microwave Limb Sounder geopotential height observations, the anomalously strong secondary planetary waves (PWs) with westward zonal wavenumber 1 and periods of 10–16 days are unexpectedly captured in the Southern (summer) Hemisphere (SH) during the Arctic sudden stratospheric final warmings (SSFWs) in 2015 and 2022, while no distinct secondary PW signal occurs in the SH during the 2005, 2014, and 2016 Arctic SSFWs. The Eliassen‐Palm (EP) flux diagnostics show that the secondary PWs during the 2015 and 2022 SSFWs have strong trans‐equatorial components at ∼35–60 km, but the southward EP flux from the Northern Hemisphere during the other three SSFWs decays dramatically around the equator. Further diagnostic results on the background conditions indicate that the phase of the quasi‐biennial oscillation (QBO) in the middle stratosphere plays a crucial role in the SH response to the secondary PW during SSFW. The strong equatorial westward winds at ∼32–42 km result in the critical layers and negative waveguides for the secondary W1 PW during the 2005, 2014, and 2016 SSFWs, which significantly block the trans‐equatorial propagation of PW. Such PW suppression is not observed during the 2015 and 2022 SSFWs since the middle stratospheric QBO is in the eastward phase. Moreover, the strong secondary PW in the SH during the 2015 and 2022 SSFWs can additionally induce the poleward residual circulation to facilitate the mesospheric total residual circulation transition from summer pattern to winter pattern in the SH. Plain Language Summary: The anomalously strong secondary planetary waves with various zonal wavenumbers and periods in the winter hemisphere during or following the sudden stratospheric warming events are observed frequently in both ground‐based and satellite observations. Previous studies suggest that there is a good correspondence between the Arctic sudden stratospheric final warming (SSFW) and the strong secondary wave with periods of 10–16 days and westward zonal wavenumber 1, which is confirmed again during a recent SSFW in 2022. As revealed by the 18‐year satellite data, the secondary wave events during the 2015 and 2022 SSFWs also have unusually large amplitudes in the Southern (summer) Hemisphere (SH), while the same response is not captured during the 2005, 2014, and 2016 SSFWs. Further analysis shows that the difference is mainly due to the phase of the quasi‐biennial oscillation in the middle stratosphere that controls the trans‐equatorial propagation of the secondary wave. The additional poleward residual circulation results from the strong secondary wave in the SH can facilitate the SH circulation transition during the 2015 and 2022 Arctic SSFWs. The above processes shed new light on the coupling in the Earth's middle atmosphere between both hemispheres, and between the polar region and the tropics. Key Points: Strong secondary planetary waves with periods of 10–16 days are observed in the Southern Hemisphere (SH) during the 2015 and 2022 Arctic sudden stratospheric final warmings The SH response to the secondary wave mainly depends on the phase of the middle stratospheric quasi‐biennial oscillation The secondary wave‐induced poleward circulation in 2015 and 2022 promotes the mesospheric circulation transition in the SH