A review of the oceanography and Antarctic Bottom Water formation offshore Cape Darnley, East Antarctica

Antarctic Bottom Water (AABW) is the densest water mass in the world and drives the lower limb of the global thermohaline circulation. AABW is formed in only four regions around Antarctica and Cape Darnley, East Antarctica, is the most recently discovered formation region. Here, we compile 40 years of oceanographic data for this region to provide the climatological oceanographic conditions, and review the water mass properties and their role in AABW formation. We split the region into three sectors (East, Central and West) and identified the main water masses, current regimes and their influence on the formation of Cape Darnley Bottom Water (CDBW). In the eastern sector, Prydz Bay, the formation of Ice Shelf Water preconditions the water (cold and fresh) that flows into the central sector to ~68.5◦E, enhancing sea ice production in Cape Darnley Polynya. This produces a high salinity variant of DSW (up to 35.15 g/kg) DSW that we coin Burton Basin DSW. In contrast, the western sector of the Cape Darnley Polynya produces a low salinity variant (up to 34.85 g/kg) we coin Nielsen Basin DSW. The resultant combined CDBW is the warmest (upper temperature bound of 0.05◦C) AABW formed around Antarctica with an upper bound salinity of ~34.845 g/kg. Our findings will contribute to planning future observing systems at Cape Darnley, determining the role CDBW plays in our global oceanic and climate systems, and modelling past and future climate scenarios.