Eleven satellite-tracked drifting buoys were deployed in the central South Atlantic Ocean during two austral summer and two austral winter cruises. Between 7¿S and 11¿S and 23¿W and 31¿W during austral winter, net buoy drift was to the west. Surface geostrophic flow was to the east between 7¿S and 9¿S. It is proposed that strong southeast trade winds can induce directly driven surface flows to the west that are more intense than the eastward geostrophic flows associated with the South Equatorial Countercurrent (SECC). A sustained period of eastward drift within the SECC was observed during austral summer, when the trades are weaker. The trajectories indicate surface waters north of 8¿S have a mean northward meridional component and those south of 8¿S a southward component. The buoys which drifted north became entrained into the North Brazilian Coastal Current (NBCC) and those that drifted south into the Brazil Current. One buoy left the NBCC at about 5¿N to drift northeastward in the North Equatorial Countercurrent (NECC). This trajectory and historical ship drift reports suggest that the NECC may extend only to 35¿W to 40¿W during boreal winter. Temperature data obtained as the buoys drifted westward and northward suggest that increases in upper layer heat content can be attributed to heat fluxes through the sea surface. |