Northwestern Weddell Sea deep outflow into the Scotia Sea during the austral summers of 2000 and 2001 estimated by inverse methods

• Language: unknown
• Published: 2007
• Subjects: Deep outflow variations; DOVETAIL; Inverse methods; Northwestern weddell sea; Weddell sea deep water; Data acquisition; Global warming; Water; Northwestern weddell; Oceanography; atmospheric forcing; deep water; estimation method; flux measurement; geostrophic flow; heat budget; ocean basin; outflow; summer; warm water; Antarctic Peninsula; Antarctica; Atlantic Ocean; Philip Passage; Powell Basin; Scotia Ridge; Scotia Sea; Southern Ocean; Weddell Sea; West Antarctica; Antarctic; Austral; South Scotia Ridge; Weddell; Antarc*
• Online Access: https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09670637_v54_n10_p1815_Franco; https://hdl.handle.net/20.500.12110/paper_09670637_v54_n10_p1815_Franco

The northward outflow of cold, dense water from the Weddell Sea into the world ocean basins plays a key role in balancing the global heat budget. We estimate the geostrophic flow patterns in the northwestern Weddell Sea using box inverse methods applied to quasi-synoptic hydrographic data collected during the Brazilian DOVETAIL 2000 and 2001 austral summer cruises. The analysis is focused on the variations of the deep Weddell Sea outflow into the Scotia Sea within boxes that bound the main deep gaps over the South Scotia Ridge. To determine the geostrophic volume transports in each box, mass, salt, and heat are conserved within neutral density layers that are not in contact with the atmosphere. Implementing the inverse model and using property anomaly equations weighted by the flow estimate uncertainty our results are consistent with those reported in the literature. A bottom triangle extrapolation method is introduced, which improves the estimated property fluxes through hydrographic sections. In the austral summer of 2000 the transports of Weddell Sea Deep Water (WSDW) through the Philip Passage, Orkney Passage, and southwestern Bruce Passage are 0.01±0.01, 1.15±0.33, and 1.03±0.23 Sv (1 Sv=106 m3 s-1, >0 is northward), respectively. After extrapolation within bottom triangles these transports increase to 0.12±0.03, 3.48±1.81, and 1.20±2.16 Sv. Analysis of the hydrographic data reveal distinct oceanographic conditions over the Philip Passage region, with evidence of mesoscale meanders, warmer and saltier Warm Deep Water (WDW) and colder WSDW observed in 2001 than in 2000. Despite these differences the WSDW transport does not present a significant variation between 2000 and 2001. The WSDW transports through the Philip Passage in 2001 are 0.012±0.001 and 0.113±0.001 Sv after extrapolation within bottom triangles. The circulation derived from the inversion in the austral summer of 2001 suggests a sharp weakening of the barotropic cyclonic flow in the Powell Basin, which may be due to northerly and ...