Australian hot and dry extremes induced by weakenings of the stratospheric polar vortex

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Lim, Eun-Pa, Hendon, Harry H., Boschat, Ghyslaine, Hudson, Debra, Thompson, David W. J. ORCID: https://orcid.org/0000-0002-5413-4376, Dowdy, Andrew J. and Arblaster, Julie M. (2019) Australian hot and dry extremes induced by weakenings of the stratospheric polar vortex. Nature Geoscience, 12. 896–901. ISSN 1752-0894

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Abstract

The occurrence of extreme hot and dry conditions in warm seasons can have large impacts on human health, energy and water supplies, agriculture and wildfires. Australian hot and dry extremes have been known to be associated with the occurrence of El Niño and other variations of tropospheric circulation. Here we identify an additional driver: variability of the stratospheric Antarctic polar vortex. On the basis of statistical analyses using observational data covering the past 40 yr, we show that weakenings and warmings of the stratospheric polar vortex, which episodically occur during austral spring, substantially increase the chances of hot and dry extremes and of associated fire-conducive weather across subtropical eastern Australia from austral spring to early summer. The promotion of these Australian climate extremes results from the downward coupling of the weakened polar vortex to tropospheric levels, where it is linked to the low-index polarity of the Southern Annular Mode, an equatorward shift of the mid-latitude westerly jet stream and subsidence and warming in the subtropics. Because of the long timescale of the polar vortex variations, the enhanced likelihood of early-summertime hot and dry extremes and wildfire risks across eastern Australia may be predictable a season in advance during years of vortex weakenings.

Item Type:	Article
Uncontrolled Keywords:	sdg 3 - good health and well-being,sdg 13 - climate action ,/dk/atira/pure/sustainabledevelopmentgoals/good_health_and_well_being
Faculty \ School:	Faculty of Science > School of Environmental Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences Faculty of Science > Research Groups > Climatic Research Unit
Related URLs:	https://publons.com/publon/30768248/
Depositing User:	LivePure Connector
Date Deposited:	13 Jun 2022 13:30
Last Modified:	15 Jun 2023 04:31
URI:	https://ueaeprints.uea.ac.uk/id/eprint/85562
DOI:	10.1038/S41561-019-0456-X

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