2003), Water mass conversion, fluxes and mixing in the Scotia Sea diagnosed by an inverse model

• Main Authors: Alberto C. Naveira Garabato, David P. Stevens, Karen J. Heywood
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; Drake Passage; Scotia Sea; South Scotia Ridge; The Antarctic; Weddell; Weddell Sea; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.516.31; http://www.noc.soton.ac.uk/soes/staff/acng/JPO_NGetal03.pdf

An inverse box model of the Scotia Sea is constructed using hydrographic, tracer, and velocity data collected along the rim of the basin during the Antarctic Large-Scale Box Analysis and the Role of the Scotia Sea (ALBATROSS) cruise. The model provides an estimate of the time-mean three-dimensional circulation as the Antarctic Circumpolar Current (ACC) crosses the region. It concurrently solves for geostrophic and wind-driven Ekman transports across the boundaries of the basin, air–sea-driven diapycnal fluxes, and ‘‘interior’ ’ diapycnal fluxes below the ocean surface. An increase is diagnosed in the ACC volume transport from 143 6 13 Sv (Sv [ 106 m3 s21) at Drake Passage to 149 6 16 Sv on leaving the Scotia Sea, supplied by the import of 5.9 6 1.7 Sv of Weddell Sea Deep Water (WSDW) over the South Scotia Ridge. There is a lateral redistribution of the transport, primarily in response to a topographically induced branching of the 70–80 Sv polar front (PF) jet and an increase in the transport associated with the subantarctic front (SAF) from 31 6 7 to 48 6 4 Sv. A vertical rearrangement of the transport also occurs, with differences O(2 Sv) in the transports of intermediate and deep water masses. These volume transport changes are accompanied by a net reduction (increase) in the heat (freshwater) flux associated with the ACC by 0.02 6 0.020 PW (0.020 6 0.017 Sv), the main cause of which is the cooling and freshening of the Circumpolar Deep Water (CDW) layer in the Scotia Sea. The model