Mesoscale baroclinic flow patterns off the Tubarão Bight and Abrolhos Bank

Passos, L. G. - Empresa Prooceano
Silveira, I. C. A. - Instituto Oceanográfico da Universidade de São Paulo (IOUSP)
Calado, L. - Instituto de Estudos do Mar Almirante Paulo Moreira (IEAPM-Marinha).

The region adjacent to the Tubarão Embayment and Abrolhos Bank is one of the least investigated areas of the Brazilian continental margin. The most recent studies of the circulation in this area were carried out during the 80’s and 90’s. Nowadays, studies focusing on the mesoscale activity and the seasonal variability of the circulation off the Brazilian eastern coast (Silva, et al., 2009; Soutelino et al., 2011) have reported complex flow patterns and caught the attention of the scientific community due to the lack of knowledge of the local dynamics. In order to comprehend the flow pattern in the region, synoptic data for 2004 and 2005 from the Abrolhos Project is used to study the main features identified in this region through numerical modelling. The initial conditions were objectively analyzed using synoptic hydrographic data and climatalogical data (WOA-01). The profiles of the synoptic and climatological data were non-dimensionalyzed and re-dimensionalyzed with sea surface temperature images and synthetic salinity fields. Then, ROMS is initialized and run for the winter of 2004 and summer of 2005 scenarios. In the winter scenario, an anticyclone, here named Tubarão Eddy, was identified inside the Tubarão Embayment, while the Vitória Eddy (VE) and the Abrolhos Eddy (AE) were only identified in the summer scenario. This is because the VE is associated with an anticyclone symmetric to the Brazil Current axis. The results show that the anticyclones offshore of the Abrolhos Bank do not present the same dynamical structure as the cyclones present in the Tubarão Embayment. We also discuss the non-permanent nature of the VE.