The recent shift in early summer Arctic atmospheric circulation

Overland, J. E., Francis, J. A., Hanna, E. and Wang, M. (2012) The recent shift in early summer Arctic atmospheric circulation. Geophysical Research Letters, 39 (19). ISSN 0094-8276

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1 The last six years (2007-2012) show a persistent change in early summer Arctic wind patterns relative to previous decades. The persistent pattern, which has been previously recognized as the Arctic Dipole (AD), is characterized by relatively low sea-level pressure over the Siberian Arctic with high pressure over the Beaufort Sea, extending across northern North America and over Greenland. Pressure differences peak in June. In a search for a proximate cause for the newly persistent AD pattern, we note that the composite 700 hPa geopotential height field during June 2007-2012 exhibits a positive anomaly only on the North American side of the Arctic, thus creating the enhanced mean meridional flow across the Arctic. Coupled impacts of the new persistent pattern are increased sea ice loss in summer, long-lived positive temperature anomalies and ice sheet loss in west Greenland, and a possible increase in Arctic-subarctic weather linkages through higheramplitude upper-level flow. The North American location of increased 700 hPa positive anomalies suggests that a regional atmospheric blocking mechanism is responsible for the presence of the AD pattern, consistent with observations of unprecedented high pressure anomalies over Greenland since 2007. ©2012. American Geophysical Union. All Rights Reserved.

Keywords:Sea ice, Sea level, Atmospheric blocking, Atmospheric circulation, Beaufort sea, Geopotential height, Greenland, High pressure, Ice loss, Ice sheet, Meridional flows, North American, Pressure differences, Proximate cause, Sea level pressure, Temperature anomaly, West Greenland, Wind patterns, Climatology, amplitude, decadal variation, geopotential, meridional circulation, wind-driven circulation, Arctic, Arctic Ocean, North America
Subjects:F Physical Sciences > F331 Atmospheric Physics
Divisions:College of Science > School of Geography
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ID Code:26033
Deposited On:10 Feb 2017 20:51

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