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Abstract

Antarctic Bottom Water (AABW) occupies most of the deep ocean, trapping heat and carbon away from the atmosphere for centuries. Despite its key role in regulating Earth’s climate on long time scales, AABW is poorly observed. This is mostly due to two factors. 1) AABW originates on the Antarctic continental shelf where in situ measurements are limited and ocean observations by satellites are hampered by persistent sea ice cover. 2) North of the Antarctic continental shelf, AABW is found below about 2000 m depth, where in situ observations are also scarce and satellites cannot provide direct measurements. Here we combine different tools, including long term monitoring obtained by ship-based surveys, recent development of autonomous observing tools in coastal Antarctic and deep ocean systems, and satellite-derived proxies, to describe temporal changes in AABW formed in the Ross Sea and its contribution to the lower limb of the Meridional Overturning Circulation. We conclude by comparing these results to what observed in other regions around Antarctica.