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Sci Adv. 2018 Jul 25;4(7):eaat6025. doi: 10.1126/sciadv.aat6025. eCollection 2018 Jul.

A stratospheric pathway linking a colder Siberia to Barents-Kara Sea sea ice loss.

Author information

1
Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN 47906 , USA.
2
Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA.
3
Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, CO 80307, USA.
4
Department of Physical and Environmental Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada.
5
International Arctic Research Center and Department of Atmospheric Sciences, University of Alaska Fairbanks, Fairbanks, AK 99775, USA.

Abstract

Previous studies have extensively investigated the impact of Arctic sea ice anomalies on the midlatitude circulation and associated surface climate in winter. However, there is an ongoing scientific debate regarding whether and how sea ice retreat results in the observed cold anomaly over the adjacent continents. We present a robust "cold Siberia" pattern in the winter following sea ice loss over the Barents-Kara seas in late autumn in an advanced atmospheric general circulation model, with a well-resolved stratosphere. Additional targeted experiments reveal that the stratospheric response to sea ice forcing is crucial in the development of cold conditions over Siberia, indicating the dominant role of the stratospheric pathway compared with the direct response within the troposphere. In particular, the downward influence of the stratospheric circulation anomaly significantly intensifies the ridge near the Ural Mountains and the trough over East Asia. The persistently intensified ridge and trough favor more frequent cold air outbreaks and colder winters over Siberia. This finding has important implications for improving seasonal climate prediction of midlatitude cold events. The results also suggest that the model performance in representing the stratosphere-troposphere coupling could be an important source of the discrepancy between recent studies.

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