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Planetary and synoptic drivers of warm and cold wintertime extremes in the High Arctic
Gabriele Messori
Visiteur LSCE, équipe ESTIMR
Jeudi 07/09/2017, 11:00-12:00
Bât. 701, P. 17C, LSCE Orme des Merisiers

The quick rise in Arctic temperatures over the last 1-2 decades has received ample coverage in both mainstream media and scientific publications. This has largely focussed on the drivers and consequences of rapid sea-ice melt. The atmospheric drivers of warm and cold wintertime temperature extremes on daily to weekly timescales have received comparatively less attention. In this paper we analyse both the large-scale and synoptic-scale circulation patterns associated with wintertime temperature extremes in the high Arctic. We find that warm extremes are systematically associated with a more meridionally-oriented large-scale circulation associated with a persistent anomalous low pressure extending from Iceland to Northern Greenland and Canada and a northward extension of the Siberian High. This favours large moisture intrusions from the Atlantic, associated with cyclones crossing the Nordic seas and local cyclogenesis in the Arctic basin. The cold extremes are instead associated with an intensification of the climatological high-latitude westerlies. This results in below-average penetration of Atlantic airmasses and in an intense radiative cooling. These findings lay the bases for an improved understanding of how the daily to weekly temperature variability in the Arctic may evolve in future climates.

Contact : Juliette Lathiere
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