Characteristics of Antarctic Stratospheric Variability During Winter: A Case Study of the 2024 Sudden Stratospheric Warming and Its Surface Impacts.
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| Title: | Characteristics of Antarctic Stratospheric Variability During Winter: A Case Study of the 2024 Sudden Stratospheric Warming and Its Surface Impacts. |
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| Authors: | Lim, Eun‐Pa1,2 (AUTHOR) eun-pa.lim@bom.gov.au, Thompson, David W. J.3,4 (AUTHOR), Butler, Amy H.5 (AUTHOR), Wheeler, Matthew C.1,2 (AUTHOR), Nakamura, Hisashi6 (AUTHOR), Jucker, Martin7,8 (AUTHOR), Arblaster, Julie M.2,9 (AUTHOR), Hendon, Harry H.9 (AUTHOR), Newman, Paul A.10,11 (AUTHOR), Coy, Lawrence11,12 (AUTHOR) |
| Source: | Journal of Geophysical Research. Atmospheres. 1/16/2026, Vol. 131 Issue 1, p1-18. 18p. |
| Subject Terms: | *Atmospheric ozone, *Ecological impact, Antarctic climate, Two thousand twenty-four, A.D., Antarctic oscillation, Vortex motion |
| Geographic Terms: | Southern Hemisphere, Antarctica |
| Abstract: | In mid‐winter 2024, extraordinary stratospheric warming occurred over the sub‐Antarctic region with two distinctive warming maxima in mid‐July to early August, followed by record negative anomalies in the southern annular mode (SAM) during late July to early August. However, the causality between these stratospheric and tropospheric extreme events remains unclear due to the rarity of such downward coupling during Southern Hemisphere (SH) winter—previous Antarctic stratospheric warmings and their associated downward coupling have largely occurred during SH spring. Here we provide insights into the dynamics and climate impacts of wintertime Antarctic vortex variability during 1979–2023 and compare the climatological behavior of wintertime SH stratosphere‐troposphere coupling with that observed during mid‐winter 2024. During 1979–2023, compared to the springtime stratospheric polar vortex variability in the SH, which is characterized by variations in vortex strength and breakdown timing and its robust signature in surface climate, wintertime variability in the SH stratospheric circulation is marked by expansion and contraction of the vortex with generally weak linkages to surface circulation. The 2024 mid‐winter event mirrored many historical features of wintertime variability at stratospheric levels but had a much stronger signature in surface climate. It was unique with a record contraction of the vortex accompanied by record increases in polar stratospheric temperatures for July. These unusual stratospheric conditions atypically led to substantially higher‐than‐normal Antarctic ozone concentrations in July and August, delaying the development of the ozone hole, and record negative values in the SAM and extraordinary warmth over the Antarctic continent in early August 2024. Plain Language Summary: In mid‐winter 2024, extraordinary stratospheric warming occurred over the sub‐Antarctic region with two spectacular sudden warming episodes in mid‐July and early August, followed by extremely high near‐surface pressure and temperatures over Antarctica in late July to early August. However, it remains unclear whether this sudden stratospheric warming (SSW) directly caused the extreme conditions in the lower atmosphere because SSW events and their downward impacts are very rare in the Southern Hemisphere (SH) during winter, more commonly occurring in spring instead. Here we provide insights into typical characteristics and downward influence of wintertime Antarctic vortex variability during 1979–2023 and compare them with that observed during mid‐winter 2024. We have found that wintertime variability in the SH stratospheric circulation is usually marked by expansion and contraction of the vortex, with only weak effects on the surface climate. Overall, the 2024 mid‐winter event resembled previous wintertime SSWs but was also unique with a record contraction of the vortex accompanied by record increases in polar stratospheric temperatures for July. These unique stratospheric conditions atypically led to a substantially delayed development of the Antarctic ozone hole and extraordinarily anomalous Antarctic surface warming and unusual circulations in the SH extratropics in early August 2024. Key Points: The sub‐Antarctic stratosphere was extraordinarily warm in July 2024 with two sudden stratospheric warming episodesThis mid‐winter event was unique with a record contraction of the vortex and resultant record warming in polar stratosphere for JulyThese exceptional conditions caused extreme Antarctic surface warming and record negative southern annular mode in early August 2024 [ABSTRACT FROM AUTHOR] |
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| Database: | GreenFILE |
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