Surface circulation and kinetic energy in the SW Atlantic obtained by drifters

This study addresses the surface oceanic circulation of the Southwest Atlantic of the SE/S Brazilian coast. The data were obtained from 15 drifters launched in groups of 5 in February and August 1993 and February 1994, in the northern portion of the study area. The semiannual mean and fluctuation of the surface currents showed a tendency to flow along the 200, 1000, and 2000 m isobaths even in different seasons. However, the mean velocities varied significantly with smaller values in the second semester. There are relevant differences in the mean conditions of the circulation and in its variability between the first semesters of 1993 and 1994. Evidence indicates that these variations are related to meteorological anomalies. The mean latitude where the deflections of these drifters occurred varied during the year. During austral winter these deflections occurred northernmost. Near 30°S, one of the drifter groups was deflected to the north on the inner shelf as a result of the northward cold water intrusion along the South Brazil continental shelf. The importance of eddies in the local circulation is discussed. Spectral analysis of the data indicated the meteorological system to be important in the surface ocean circulation in the region.