Estudo da influência da dinâmica da plataforma continental nas baías de Ilha Grande e Sepetiba via aninhamento de modelo numérico costeiro a modelo numérico oceânico

Abstract

Previous works in the region of Ilha Grande and Sepetiba Bay (BIGS) sought the representation of astronomical tide, rivers and local winds contributions in its circulation, whose effects cause relatively strong currents in the interior portion of Sepetiba’s Bay (BS), up to 60 cm/s, and weaker in the Ilha Grande Bay (BIG) and around the Ilha Grande (IG), up to 20cm/s. In the last two places, meteorological tide currents, due subinercial effects from continental shelf waves (CSW), modulating astronomical tide currents, with intensity values up 60 cm/s, in the IG Channel and up to 40 cm/s in the BIG, playing a major rule in its circulation. In the BS the residual circulation has a magnitude of 5 cm/s or less. This thesis presents a contribution to the description of subinercial effects that are of fundamental importance for a better characterization of the BIGS circulation. The methodology consisted in using results from the HYCOM global ocean model, grid of 1/12 °, in Summer and Winter scenarios, to represent CSW’s effects into a coastal simulation of BIGS with the SisBaHiA model. The results, evaluated against available in situ data, indicated that during the winter, the subinercial contribution caused a substantial increase of circulation in the BIG and the SEP entrances, and around IG, with a minor contribution into BS. The T50, i.e. the time for renewal of 50% of the water into the BIGS, was reduced by a half. Summer’s simulations showed an increase in transport, although with less renewal then in the winter. This study provides an adequate evaluation of the effects of residual circulation in the BIGS, which are very important for the studies concerning sediment transport, pollutants tracking, water quality, etc.