A numerical study of the effects of bottom topography and coastline geometry on the Southeast Brazilian coastal upwelling

Abstract

A two-layer finite element model is used to investigate the effects of bottom topography and coastline geometry on the coastal upwelling of the Southeast Brazilian continental shelf. Three cases are analyzed: (1) real topography and real coastline; (2) flat bottom and real coastline and (3) real topography and smoothed coastline. For all the numerical simulations the model was integrated for five days using a constant northeast wind. The first case reproduces reasonably well the characteristics of wind-driven upwelling with respect to location and magnitude. When comparing the second and third case results with the first one, it can be seen that local bottom topography and coastline geometry affect the upwelling magnitude in the whole domain. The coastline irregularities are important in the location of the upwelling cores in the south portion, which extends from Cabo de São Tomé to Rio de Janeiro, primarily near Cabo Frio. Moreover bottom topography seems to be responsible for the location of the upwelling cell in the north portion of the domain, from Cabo de São Tomé to Vitória. In contrast to previous findings, the coastline irregularities are found to dominate over topographic variations in determining the location of Cabo Frio coastal upwelling.