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The role of eddies in the Southern Ocean temperature response to the Southern Annular Mode

Screen, James A.; Gillett, Nathan P.; Stevens, David P.; Marshall, Gareth J.; Roscoe, Howard K.. 2009 The role of eddies in the Southern Ocean temperature response to the Southern Annular Mode. Journal of Climate, 22 (3). 806-818. 10.1175/2008JCLI2416.1

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Abstract/Summary

The role of eddies in modulating the Southern Ocean response to the southern annular mode (SAM) is examined, using an ocean model run at multiple resolutions from coarse to eddy resolving. The high-resolution versions of the model show an increase in eddy kinetic energy that peaks 2-3 yr after a positive anomaly in the SAM index. Previous work has shown that the instantaneous temperature response to the SAM is characterized by predominant cooling south of 45 degrees S and warming to the north. At all resolutions the model captures this temperature response. This response is also evident in the coarse-resolution implementation of the model with no eddy mixing parameterization, showing that eddies do not play an important role in the instantaneous response. On the longer time scales, an intensification of the mesoscale eddy field occurs, which causes enhanced poleward heat flux and drives warming south of the oceanic Polar Front. This warming is of greater magnitude and occurs for a longer period than the initial cooling response. The results demonstrate that this warming is surface intensified and strongest in the mixed layer. Non-eddy-resolving models are unable to capture the delayed eddy-driven temperature response to the SAM. The authors therefore question the ability of coarse-resolution models, such as those commonly used in climate simulations, to accurately represent the full impacts of the SAM on the Southern Ocean.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1175/2008JCLI2416.1
Programmes: BAS Programmes > Global Science in the Antarctic Context (2005-2009) > Long-Term Monitoring and Survey – Physical Sciences Division
BAS Programmes > Polar Science for Planet Earth (2009 - ) > Climate
ISSN: 0894-8755
NORA Subject Terms: Marine Sciences
Meteorology and Climatology
Earth Sciences
Atmospheric Sciences
Date made live: 11 Nov 2010 14:06
URI: http://nora.nerc.ac.uk/id/eprint/11205

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