The recent shift in early summer Arctic atmospheric circulation
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Material Information

Title:
The recent shift in early summer Arctic atmospheric circulation
Series Title:
Geophysical Research Letters Volume 39
Creator:
James E. Overland
Jennifer A. Francis
Edward Hanna
Muyin Wang
Affiliation:
National Oceanic and Atmospheric Administration -- Pacific Marine Environmental Laboratory
Rutgers University -- Institute of Marine and Coastal Sciences
University of Sheffield -- Department of Geography
University of Washington -- Joint Institute for the Study of the Atmosphere and Oceans
Publisher:
American Geophysical Union
Publication Date:
Language:
English

Notes

Abstract:
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.

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Florida International University
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Aggregations:
Sea Level Rise