Standing and Transient Eddies in the response of the Southern Ocean Meridional Overturning to the Southern Annular Mode

• Main Authors: C. O. Dufour, J. Le Sommer, J. D. Zika, M. Gehlen, J. C. Orr, P. Mathiot
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2012
• Subjects: Antarctic; Southern Ocean; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.397.3840; http://hal.inria.fr/docs/00/69/70/90/PDF/manuscript.pdf

To refine understanding of how Southern Ocean responds to recent intensification of the Southern Annular Mode (SAM), a regional ocean model at two eddy-permitting resolutions was forced with two synthetic interannual forcings. The first forcing corresponds to homogeneously intensified winds, while the second concerns their poleward intensification, consistent with positive phases of the SAM. Resulting wind-driven responses differ greatly between the nearly insensitive Antarctic Circumpolar Current (ACC) and the more sensitive Meridional hal-00592264, version 3- 14 May 2012 Overturning Circulation (MOC). As expected, eddies mitigate the response of the ACC and MOC to poleward intensified winds. However, transient eddies do not necessarily play an increasing role in meridional transport with increasing winds and resolution. As winds increase, meridional transport from standing eddies becomes more efficient at balancing wind-enhanced overturning. These results question the current paradigms on the role of eddies and present new challenges for eddy flux parameterization. Results also indicate that spatial patterns of