High Salinity Shelf Water production rates in Terra Nova Bay, Ross Sea from high-resolution salinity observations

Abstract

High Salinity Shelf Water (HSSW) formed in the Ross Sea is a precursor to Antarctic Bottom Water(AABW), a water mass that constitutes the bottom limb of the global overturning circulation. HSSW production rates are poorly constrained, as in-situ observations are scarce. Here, we present high vertical-and-temporal-resolution salinity time series collected in austral winter 2017 from a mooring in Terra Nova Bay (TNB), one of two major sites of HSSW production in the Ross Sea. We calculate an annual-average HSSW production rate of ~0.4 Sv (106 m3 s-1), which we use to ground truth additional estimates across 2012 - 2021 made from parametrized net surface heat fluxes. We find sub seasonal and interannual variability on the order of 0.1 Sv, with a strong dependence on variability in open-water area that suggests a sensitivity of TNB HSSW production rates to changes in the local wind regime and offshore sea ice pack.