On the export of dense water from the Weddell and Ross Seas

We describe the seasonal and interannual variability of volume transports in Weddell and Ross Seas using the 1/12deg; 20-yr simulation of the OCCAM global ocean general circulation model. The average simulated full-depth cumulative 28.5 plusmn; 2.9 Sv (1 Sv equiv; 106 m3 s-1) and 13.4 plusmn; 5.2 Sv, across the main export regions of the Weddell and Ross Seas, respectively. The values of mean outflow of Antarctic Bottom Water (AABW) (defined by neutral density gamma;n 28.27 kg m-3) from the Weddell and Ross Seas of 10.6 plusmn; 3.1 Sv and 0.5 plusmn; 0.7 Sv, respectively, agree with the range reported in historical observational studies. Variability in AABW export is predominantly at periods of ~1 yr and 2-4 yr. The transit time taken by AABW sourced in the Southern Weddell Sea to reach the main Weddell export zone is ~2 yr. Lagged correlation between the thermohaline properties of AABW source waters and AABW export indicates that recent shelf waters freshening trends are likely related to changes in the AABW outflow rates.