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