On the circulation in the upper layer of the western equatorial Atlantic

Hydrographic observations of pressure, temperature, salinity, dissolved oxy gen, and shipboard acoustic Doppler current profiler measurements are used to study the upper layer circulation in the western equatorial Atlantic Oce an, limited to the region bounded by the 10 degrees S and 14 degrees N lati tudes between the longitudes 30 degrees W and 52 degrees W. Data were obtai ned during four World Ocean Circulation Experiment cruises, carried out in January-March 1993, January-March 1994, September-October 1995, and April-M ay 1996. In the upper layer, the continuity of the northwestward flowing No rth Brazil Current along the American continent toward the Caribbean Sea is confirmed in boreal spring. Furthermore, part of the North Brazil Current also continues northwestward in the subthermocline layer during short perio ds in boreal spring, contrary to previous estimates. The North Equatorial C ountercurrent (NECC) is present in boreal spring west of 40 degrees W, fed with water of Northern Hemisphere origin only. The southeastward flowing cu rrent observed at 3N-44 degrees W is fed by the North Brazil Current retrof lection and by a cyclonic recirculation of the southern edge of the North E quatorial Current. The upper layer of this current, at 3 degrees N-44 degre es W, feeds the Equatorial Undercurrent (EUC) and the NECC, when its subthe rmocline layer feeds the EUC and the North Equatorial Undercurrent. Near-su rface eastward flow is present above the EUC during all cruises, yielding t o a strong increase of the eastward warm water transport.