EXPORTAÇÃO DE ÁGUAS PROFUNDAS NA REGIÃO NOROESTE DO MAR DE WEDDELL, ANTÁRTICA: ÊNFASE NA VARIABILIDADE TEMPORAL

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The outflow of cold, dense water from the Weddell Sea into the ocean basins to the north plays a key role in balancing the global heat budget. We estimate the geostrophic flow patterns in the northwestern Weddell Sea during the Brazilian DOVETAIL 2000 and 2001 austral summer cruises, using box inverse methods applied to hydrographic data. 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 layers that are not in contact with the atmosphere and defined by neutral surfaces. 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 new bottom triangle extrapolation method is introduced, which improves the estimated property fluxes through hydrographic sections. During the austral summer of 2000 the Weddell Sea Deep Water (WSDW) transports 0.01 0.01, 1.15 0.32 and 1.03 0.23 Sv (1Sv = 106 m3.s-1, >0 is northward) over the Philip Passage, Orkney Passage and Bruce Passage, respectively. After extrapolation within bottom triangles these transports are 0.12 0.03, 3.46 1.81 and 1.20 2.15 Sv. 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. In spite of the properties differences observed the WSDW transport does not present a significant variation between 2000 and 2001. The WSDW transports 0.012 0.001 Sv and 0.113 0.002 Sv when extrapolating in the 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. The observed weakening may be due to northerly and northeasterly winds associated to an atmospheric low pressure center located west of the Antarctic Peninsula.

ASSUNTO(S)

noroeste do mar de weddell variação do fluxo profundo método inverso água profunda do mar de weddell oceanografia fisica

ACESSO AO ARTIGO

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