Rapid Southern Ocean front transitions in an eddy-resolving ocean GCM

Abstract

The formation of persistent multiple fronts is an established feature of the Antarctic Circumpolar Current (ACC). Front strength and location are closely linked to eddy properties and therefore have important implications for the eddy-driven closure of the Southern Ocean meridional overturning circulation. ACC front structure is analyzed here by calculating regional probability density functions (PDFs) of potential vorticity diagnosed in an eddy-resolving ocean general circulation model. Rapid spatial transitions in the number of fronts and in the density classes over which they occur are found. Front transitions are associated with the major topographic obstacles Kerguelen Island, Campbell Plateau and Drake Passage; multiple fronts are preferentially found downstream of these features. These findings highlight the significant departure from zonal symmetry of the ACC front structure and emphasize the importance of local dynamics on large-scale Southern Ocean properties. © 2010 by the American Geophysical Union.