South Atlantic interbasin exchanges of mass, heat, salt and anthropogenic carbon

作者：Evans G R^*; McDonagh E L; King B A; Bryden H L; Bakker D C E; Brown P J; Schuster U; Speer K G; van Heuven S M A C

来源：Progress in Oceanography, 2017, 151: 62-82.

DOI：10.1016/j.pocean.2016.11.005

The exchange of mass, heat, salt and anthropogenic carbon (Cant) between the South Atlantic, south of 24 degrees S, and adjacent ocean basins is estimated from hydrographic data obtained during 2008-2009 using an inverse method. Transports of anthropogenic carbon are calculated across the western (Drake Passage), eastern (30 degrees E) and northern (24 degrees S) boundaries. The freshwater overturning transport of 0.09 Sv is southward, consistent with an overturning circulation that exports freshwater from the North Atlantic, and consistent with a bistable Meridional Overturning Circulation (MOC), under conditions of excess freshwater perturbation. At 30 degrees E, net eastward Antarctic Circumpolar Current (ACC) transport, south of the Subtropical Front, is compensated by a 15.9 +/- 2.3 Sv westward flow along the Antarctic boundary. The region as a whole is a substantial sink for atmospheric anthropogenic carbon of 0.5 +/- 0.37 Pg C yr(-1), of which 0.18 +/- 0.12 Pg C yr(-1) accumulates and is stored within the water column. At 24 degrees S, a 20.2 Sv meridional overturning is associated with a 0.11 Pg C yr(-1) Cant overturning. The remainder is transported into the Atlantic Ocean north of 24 degrees S (0.28 +/- 0.16 Pg C yr(-1)) and Indian sector of Southern Ocean (1.12 0.43 Pg C yr(-1)), having been enhanced by inflow through Drake Passage (1.07 0.44 Pg C yr-1). This underlines the importance of the South Atlantic as a crucial element of the anthropogenic carbon sink in the global oceans.