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Abstract Oceanographic changes adjacent to Antarctica have global climatic and ecological impacts. However, this is the most challenging place in the world to obtain marine data due to its remoteness and inhospitable nature, especially in winter. Here, we present more than 2000 Conductivity-Temperature-Depth (CTD) profiles and associated water sample data collected with (almost uniquely) full year-round coverage from the British Antarctic Survey Rothera Research Station at the west Antarctic Peninsula. Sampling is conducted from a small boat or a sled, depending on the sea ice conditions. When conditions allow, sampling is twice weekly in summer and weekly in winter, with profiling to nominally 500 m and with discrete water samples taken at 15 m water depth. Daily observations are made of the sea ice conditions in the area. This paper presents the first 20 years of data collection, 1997-2017. This time series represents a unique and valuable resource for investigations of the high-latitude ocean’s role in climate change, ocean/ice interactions, and marine biogeochemistry and carbon drawdown.

Abstract The Atlantic sector of the Southern Ocean is the world’s main production site of Antarctic Bottom Water, a water-mass that is ventilated at the ocean surface before sinking and entraining older water-masses—ultimately replenishing the abyssal global ocean. In recent decades, numerous attempts at estimating the rates of ventilation and overturning of Antarctic Bottom Water in this region have led to a strikingly broad range of results, with water transport-based calculations (8.4–9.7 Sv) yielding larger rates than tracer-based estimates (3.7–4.9 Sv). Here, we reconcile these conflicting views by integrating transport- and tracer-based estimates within a common analytical framework, in which bottom water formation processes are explicitly quantified. We show that the layer of Antarctic Bottom Water denser than 28.36 kg m $$^{-3}$$ - 3 $$\gamma _{n}$$ γ n is exported northward at a rate of 8.4 ± 0.7 Sv, composed of 4.5 ± 0.3 Sv of well-ventilated Dense Shelf Water, and 3.9 ± 0.5 Sv of old Circumpolar Deep Water entrained into cascading plumes. The majority, but not all, of the Dense Shelf Water (3.4 ± 0.6 Sv) is generated on the continental shelves of the Weddell Sea. Only 55% of AABW exported from the region is well ventilated and thus draws down heat and carbon into the deep ocean. Our findings unify traditionally contrasting views of Antarctic Bottom Water production in the Atlantic sector, and define a baseline, process-discerning target for its realistic representation in climate models.