Contrasting circulation patterns between surface and intermediate layers in the North Brazil current system

I Encuentro de la Oceanografía Física Española (EOF), 13-15 de octubre 2010, Barcelona

A regional survey of the western equatorial Atlantic, carried out as part of the MOC2 project in April 2010, formed a closed box with the northeastern Brazilian coast. Direct ocean current measurements from lowered‐ADCP are used to describe the main circulation patterns and to estimate the transports of the major currents within the upper 1100 m of the North Brazil Current (NBC) System. In the surface layer (0‐400 m), the NBC was found to be an intense boundary current transporting northwestward ‐14.4 ± 0.3 Sv near 5°S. This current strengthened to the north by 2.2 Sv at 1°S apparently due to contributions of the NBC retroflection and North Equatorial Countercurrent (NECC). The zonal flow was dominated by a meandering Equatorial Undercurrent (EUC) which left the box at the east with 9.5 ± 0.4 Sv. In the intermediate layer (400‐1100 m), the North Brazil Undercurrent (NBUC) flowed northwestward into the box with a transport of ‐8.4 ± 0.3 Sv. Below the EUC, the Equatorial Intermediate Current (EIC) carried ‐6.0 ± 0.5 Sv westward and then it branched, with one branch flowing northwestward to feed the North Equatorial Intermediate Current (NEIC). The net imbalances of the surface and intermediate layers are estimated to be 0.7 ± 0.5 Sv and ‐0.1 ± 0.5 Sv, respectively. Model solutions are analyzed for comparison with the observational results, as well as to gain a better understanding of the regional circulation seasonality

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