Role of Arctic sea ice loss in autumn in the polar vortex splitting in winters 1984/1985, 1998/1999, and 2012/2013
E.S. Savelieva, V.V. Zuev
Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of the Russian Academy of Sciences, Tomsk, Russia
Keywords: polar vortex, Arctic sea ice, Beaufort Sea, Canadian Arctic Archipelago, planetary waves
Abstract
The Arctic stratospheric polar vortex usually forms in autumn, reaches its peak intensity in mid-winter, and decays in spring. The polar vortex strength and persistence in the winter-spring period play an important role in stratospheric ozone depletion with the return of solar radiation in late winter. In this study, we investigated the causes of the unusual weakening of the Arctic stratospheric polar vortex in winters 1984/1985, 1998/1999, and 2012/2013. The unusually early (from late December to early January) splitting of the Arctic polar vortex in those years was observed in mid-winter, after which the polar vortex did not recover for at least a month or until next autumn. We showed that such vortex dynamics was caused by an unusually prolonged increase in the activity of vertically propagating planetary waves for more than two weeks in the first half of winter in the lower stratosphere as a result of a record decrease in sea ice area and a corresponding increase in surface temperature in those years in the Beaufort Sea, the Canadian Arctic Archipelago, and the Central Arctic in November.
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