On the Dynamics of Salvador Canyon, Bahia – Brazil (13°S)

Abstract

The dynamics of a large (∼ 22 km wide) and deep (∼ 600 m deep) submarine canyon was investigated using data from three ADCP transects perpendicular to the coast: i) at the canyon axis and ii) at the northern and southern adjacent shelves, as well as high resolution CTD data collected at various hydrographic stations located in each transect. In order to represent the seasonal cycle, the region was seasonally covered during a whole year. Preliminary results show that the wind forcing exerted a great influence on the coastal circulation at the northern and southern canyon’s adjacent shelves. At the canyon’s head, a topographically trapped cyclonic circulation was observed, being intensified during downwelling favorable winds. Its cyclonic circulation affected the coastal circulation at northern adjacent shelf, which showed a surface reversal in comparison to the preferential shelf flow. At depths around 200 m, and below the canyon rim, the flow field was also disturbed by the canyon topography. Vertical hydrographic profiles confirm the strong wind influence to the local dynamics. During the winter season a deeper isothermal layer (∼200 m deep) was observed, caused by the intense mixing promoted by stronger winds, due to the influence of cold front passages.