Weakening of the stratospheric polar vortex by Arctic sea-ice loss
Wednesday, 17 December 2014: 11:20 AM
Successive cold winters in recent years have had critical social and economic impacts on the mid-latitude continents in the Northern Hemisphere. In this study, 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.