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An anomalous late-season change in the regional sea ice regime in the vicinity of the Mertz Glacier Polynya, East Antarctica

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Massom, RA and Jacka, K and Pook, MJ and Fowler, C and Adams, N and Bindoff, NL (2003) An anomalous late-season change in the regional sea ice regime in the vicinity of the Mertz Glacier Polynya, East Antarctica. Journal of Geophysical Research, 108 (C7). pp. 1-15. ISSN 0148-0227

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Abstract

This paper examines a major late-season shift in atmospheric circulation over the East Antarctic sea ice zone that occurred in October 1999. The mean wind direction at 65S, 145E changed from south-southeasterly to west-southwesterly, resulting in almost a complete reversal of the climatological East Wind Drift pattern in large-scale sea ice advection over the Southern Ocean sector 135–170E. By comparison with National Centers for Environmental Prediction/National Center for Atmospheric Research Reanalysis time series from 1980 to 2000, this shift is shown to be unusual in terms of both its persistence and impact, although similar though less prolonged patterns occurred in 1984 and 1985. Lasting from October 1999 to February 2000, it had a profound impact on sea ice concentration and extent over a vast area. By coinciding with the period of maximum ice extent and persisting through to the springtime melt phase, it also contributed to the rapid annual meltback of sea ice. It also had a large and complex effect on the behavior of the globally important Mertz Glacier Polynya and on the areal extent of thick perennial sea ice to the east. While a midlatitude blocking high pattern provided the initial impetus for the ‘‘shift’’ in 1999, the persistence of west-southwesterly winds through February 2000 appears to relate to an unusually persistent southward migration of the Antarctic Circumpolar Trough (ACT). In addition to the prolonged 1999 episode, a strong seasonal signal is apparent throughout the mean wind speed and direction time series, related to the ACT migration. Although less persistent than in 1999, this annual shift has implications for the observed dramatic annual meltback of East Antarctic sea ice.

Item Type: Article
Journal or Publication Title: Journal of Geophysical Research
Page Range: pp. 1-15
ISSN: 0148-0227
Identification Number - DOI: 10.1029/2002JC001354
Additional Information: Copyright 2003 American Geophysical Union
Date Deposited: 28 May 2008 23:58
Last Modified: 18 Nov 2014 03:40
URI: http://eprints.utas.edu.au/id/eprint/6379
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