On the formation of Antarctic Intermediate and Bottom Water in ocean general circulation models

Abstract

A series of coarse-resolution models were integrated with a view to determining the most appropriate representation of the largest-scale water masses formed in the Southern Ocean. The ocean model employed has a global domain with a realistic approximation of the continental outlines and bottom bathymetry. The annual mean forcing at the sea surface is derived from climatological fields of temperature, salinity, and wind stress. It is found that the salinity of shelf water in the Weddell and Ross seas is critical if the model is to appropriately simulate the world's intermediate and bottom water masses. It is also suggested that the sea-ice component of climate models is critical if the simulation is to capture the high-salinity shelf water and bottom-water formation adjacent to Antarctica and, in turn, allow for a realistic tongue of low-salinity Antarctic Intermediate Water (AAIW). The bathymetry of the Drake Passage is shown to determine the shape and strength of an intense meridional overturning cell in the Southern Ocean. -from Authors