Observação da Variação Espectral e Posicional da Frente Brasil–Malvinas por Sensoriamento Remoto

Abstract

The Brazil–Malvinas Confluence (BMC) is formed by the encounter of the Brazil Current (BC) with the Malvinas Current (MC) at the South Atlantic ocean. This is one of the most energetic regions of the world oceans and it is characterized by intense meridional sea surface temperature gradients. Satellite data and in situ observations often reveal the presence of cyclonic and anticyclonic meanders and vortices at the BMC region. The sea surface height anomaly (SSHA) and the sea surface temperature (SST) fields of the Brazil–Malvinas Frontal (BMF) region can be used to determine the energy variations associated with the annual and bi–annual Rossby waves that occur at its sur- roundings and to detect the position of the thermal front. Our study involved the de- termination of the BMF meridional displacement on an interannual scale, the spectral variations of the Rossby wave field at the BMC region, and the variability associated to the mean absolute geostrophic velocities. The Rossby wave spectra at the BMC for 2001–2008 show an increase of the energy associated with both the annual and bi–annual periods relative to the 1993– 2000 interval. These spectral changes are not directly related to the mean changes in the thermal front region, however we detected a significant meridional variability of the mean position of the front most probably due to an increase in the BC flux. Large variations were also observed in the geostrophic velocity field for the 2001–2008 period. These maps exhibited a farther south location of the BC. This corro- borates the variability increase due to a greater instability introduced by the planetary waves at the BMC region