| Summary: | IX Simposio de Estudios Polares del Comité Español del Scientific Committee on Antarctic Research (SCAR), 5-7 September 2018, Madrid, España.-- 1 page The circulation and hydrography of the Southern Ocean is dominated by the wind-driven Antarctic Circumpolar Current (ACC) that flows eastward around Antarctica, connecting the Pacific, Atlantic and Indian Oceans. Five major topographic features strongly condition ACC flow pattern. The Drake Passage restricts its latitudinal extent connecting the Pacific and Atlantic Oceans, encountering, to the east, the formidable Scotia Sea ridge system. The most prominent discontinuities in the north ridges are: the 54-54 Passage, between 54.8ºW and 53.3ºW; the Shag Rocks Passage, the deepest gap, situated between 49.6ºW and 47.1ºW; the Black Rock Passage, the narrowest one at 40ºW, within North Scotia Ridge; and the Georgia Passage, a 3200 m depth gap between 34.2ºW and 28.9ºW, laying amidst the North Scotia Ridge and the South Sandwich Arc. All of them are of extreme importance in determining the flow patterns, front variability and structure of the water input to the South Atlantic Ocean. The water mass exchange betweenthe Southern Ocean and the South Atlantic Ocean remains poorly documented, especially through in situ observations. The main objective of this study is to describe the parameter alterations and quantify the flow of Southern Ocean waters across the different passages in the North Scotia Ridge and Georgia Passage. The methodology followed uses Argo floats data to construct seasonal and annual mean hydrographic sections from the sea surface to 2000 m, spanning the passages in a 0.5º wide area. Moreover, thesesections will be used to calculate the geostrophic transports, which will be compared with the principal access pathways as deduced from the float trajectories. The preliminary results show that the predominant access of the ACC waters to the South Atlantic Ocean occurs across the North Scotia Ridge discontinuities, the Shag Rocks Passage being the ...
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