Impacto dos processos de meso- e de submesoescala sobre as trocas de águas entre plataforma continental e oceano aberto na região de ressurgência entre Cabo de São Tomé e Cabo Frio (RJ, 22°S - 23°S)

• Autor(a) principal: Telles, Fernanda da Silva
• Data de Publicação: 2019
• Outros Autores: [e-mail]
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/18669
• topic: Shelf-open ocean exchanges; Mesoscale eddies.; Submesoscale filaments; Trocas plataforma-oceano aberto; Vórtices de mesoescala; Filamentos de submesoescala; CIENCIAS EXATAS E DA TERRA::OCEANOGRAFIA::OCEANOGRAFIA FISICA

The impact of meso- and submesoscale processes on the exchange of waters between the continental shelf and the open ocean was investigated based on simulations of a regional numerical model implemented in the Brazilian continental margin in two horizontal resolutions (6km and 2km). While flows along the continental shelf and their forcing mechanisms are relatively well known in the region, flows across the continental shelf are less investigated and hence less estimated. In part because cross-shelf velocities are weaker than along-shelf velocities which are associated with strong boundary currents flows. However, in this work, results indicate that even weaker, when driven by smaller-scale physical processes, flows into the open ocean are also significant. In the coastal region and in the shelf-break upwelling of cold waters injects nutrients on the shelf, if transported to the open ocean, may favor environments previously considered oligotrophic as productive as coastal regions. However, more intense flows in the shelf-break tend to be a physical barrier to fluid exchange. The fluxes between these two environments become possible between 20°S and 26°S, as the complex bottom topography and the coast geometry potentiate the generation of mesoscale eddies of the Brazilian Current (BC), which, in turn, induce the emergence of submesoscale processes. Cross-shelf transport was computed by integrating the resulting velocity that crosses the shelf-break in a vertical plane formed by the 200- meter isobath and its surface projection. On average, over three years of simulation there is a total transport of ~ 2 Sv off the shelf between 22°S - 23°S and ~ 1 Sv (in module) for the coast between 23°S - 24°S. In daily image analysis the fluxes are interconnected in these sectors by the ciclonic movement of the BC eddies. These eddies promote outflow flows in the sector to the north and due to the cyclonic movement towards the coast they transport waters to the continental shelf in the sector to the south. Submesoscale processes associated with the presence of these eddies promote upwelling in the out-shelf by configuring preferential upwelling sites over the shelf-break in a long period average. The results suggest that eddies, in connection with intense vertical velocities at submesoscale, induce the periodic exportation of water through the shelf and are therefore important mechanisms for the expansion of coastal productive waters in the adjacent oligotrophic ocean basin.