Study of the velocity field of surface currents in the South Atlantic Ocean derived from drifting buoy data

Abstract

A total of 1442 data series of 996 drifters from public and research databases were analyzed in order to decompose and to estimate the velocity field of surface currents between 30º S and 50º S in the South Atlantic Ocean, with emphasis on the South Atlantic Current (SAC). The SAC is the southernmost limit of the South Atlantic Subtropical Gyre and presents strong interaction with other currents such as the Antarctic Circumpolar Current (ACC). The data were processed according to the Taylor's theory. The velocity field map for the study area as well as the mean values of the current intensity and associated standard deviation are presented and discussed. The highest estimated values of the average current velocity are located at the origin of the SAC and at the Malvinas Current (MC). The mean intensity of the SAC is approximately 30 cm.s-1 and the highest intensity values are observed at its origin decaying towards east. The SAC comprises a system containing a main axis and two branches, north and south. The N-SAC feeds the Benguela Current and the S-SAC leaks to the east towards the Indian Ocean. The flow pattern observed for the SAC presents a meandering characteristics and high variability in the regions where it interacts with other currents and mesoscale features.