title: Weakening of the stratospheric polar vortex by Arctic sea-ice loss.
abstract: 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.
authors.affiliation: Division of Polar Climate Change Research, Korea Polar Research Institute, Incheon 406-840, Korea.
authors.forename: Baek-Min
authors.initials: BM
authors.lastname: Kim
authors.affiliation: School of Earth and Environmental Sciences, Seoul National University, Seoul 151-742, Korea.
authors.forename: Seok-Woo
authors.initials: SW
authors.lastname: Son
authors.affiliation: School of Environmental Science and Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Seung-Ki
authors.initials: SK
authors.lastname: Min
authors.affiliation: Department of Oceanography, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Jee-Hoon
authors.initials: JH
authors.lastname: Jeong
authors.affiliation: Division of Polar Climate Change Research, Korea Polar Research Institute, Incheon 406-840, Korea.
authors.forename: Seong-Joong
authors.initials: SJ
authors.lastname: Kim
authors.affiliation: International Arctic Research Center and Department of Atmospheric Sciences, University of Alaska, Fairbanks, Alaska 99775, USA.
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Oceanography, Chonnam National University, Gwangju 500-757, Korea.
authors.forename: Taehyoun
authors.initials: T
authors.lastname: Shim
authors.affiliation: Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
authors.forename: Jin-Ho
authors.initials: JH
authors.lastname: Yoon