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

• Main Authors: James A. Screen, Nathan, P. Gillett, David P. Stevens, Gareth J. Marshall, Howard, K. Roscoe
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2009
• Subjects: Southern Ocean
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.527.7726; http://www.cccma.ec.gc.ca/papers/ngillett/PDFS/i1520-0442-22-3-806.pdf

The role of eddies in modulating the Southern Ocean response to the southern annular mode (SAM) is examined, using anoceanmodel run atmultiple resolutions fromcoarse to eddy resolving.The high-resolution versions of themodel 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 charac-terized by predominant cooling south of 458S 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 themodel with no eddymixing 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 en-hanced 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. 1.