Polar low tracks over the Nordic Seas: a 14-winter climatic analysis

Abstract : To develop a 14-winter (October–April; 1999–2013) climatic description of polar low (PL) occurrence for the Nordic Seas, systems have been tracked using images acquired from the Very High Resolution Radiometer (AVHRR). Also, the dominant PL characteristics – their temporal and spatial distributions, size, lifespan, distance travelled, speed of propagation and directions – have been determined. On average, 14 PL events occur per winter but there is strong inter-annual and intra-seasonal variability. Although systems may form and travel over the whole Nordic Seas, their genesis is enhanced in areas characterised by warm oceanic currents. At the start of the season (October–November), systems mainly form over the Greenland and Norwegian Seas, but further into winter they form increasingly over the Barents Sea. In connection with recent low-ice winters, new areas of PL formation are evident, particularly to the west of Spitsbergen and in the Barents Sea. PL speeds of propagation range between 5 and 13 m/s but are observed to be highly variable among cases and even during the lifespan of individual PLs. To a considerable extent, the direction of movement is controlled by the large-scale flow in the lowest atmospheric layers, but we also observed cyclonic co-rotation of some pairs of PLs due to their influence on the ambient flow. Although these generally move southward or southeastward, a substantial number of PLs have westward and even northward tracks. PLs in the western part of the region average larger than their eastern counterparts. This study also highlights that PLs characteristics and tracks differ according to weather regimes.
Type de document :
Article dans une revue
Tellus A, Co-Action Publishing, 2015, 67 (1), 〈10.3402/tellusa.v67.24660〉
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Contributeur : Zhiwei Zhu <>
Soumis le : mercredi 12 septembre 2018 - 14:43:22
Dernière modification le : jeudi 21 mars 2019 - 13:18:51

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Maxence Rojo, Chantal Claud, Paul-Etienne Mallet, Gunnar Noer, Andrew Carleton, et al.. Polar low tracks over the Nordic Seas: a 14-winter climatic analysis. Tellus A, Co-Action Publishing, 2015, 67 (1), 〈10.3402/tellusa.v67.24660〉. 〈hal-01872789〉



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