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Weakening of the stratospheric polar vortex by Arctic sea-ice loss

2014; Nature Portfolio; Volume: 5; Issue: 1 Linguagem: Inglês

10.1038/ncomms5646

2041-1723

Baek‐Min Kim, Seok‐Woo Son, Seung‐Ki Min, Jee‐Hoon Jeong, Seong‐Joong Kim, Xiangdong Zhang, Taehyoun Shim, Jin‐Ho Yoon,

Cryospheric studies and observations

Successive cold winters of severely low temperatures in recent years have had critical social and economic impacts on the mid-latitude continents in the Northern Hemisphere. Although these cold winters are thought to be partly driven by dramatic losses of Arctic sea-ice, the mechanism that links sea-ice loss to cold winters remains a subject of debate. Here, by conducting observational analyses and model experiments, we show how Arctic sea-ice loss and cold winters in extra-polar regions are dynamically connected through the polar stratosphere. We find that decreased sea-ice cover during early winter months (November–December), especially over the Barents–Kara seas, enhances the upward propagation of planetary-scale waves with wavenumbers of 1 and 2, subsequently weakening the stratospheric polar vortex in mid-winter (January–February). The weakened polar vortex preferentially induces a negative phase of Arctic Oscillation at the surface, resulting in low temperatures in mid-latitudes. The mechanism behind the severely cold winters experienced by the mid-latitudes of the Northern Hemisphere in recent years is not fully understood. Here, the authors combine observational analyses and model experiments to reveal a dynamic connection between Arctic sea-ice cover and the polar stratosphere.