Equatorial Undercurrent

South America to about the date line (180 ). These trade winds also drive near-equatorial surface flow westward as the South Equatorial Current (SEC). This piles up warm surface water in the western Pacific to create a deep warm pool and results in depression of the depth of the thermocline from east to west. The westward flow in the surface SEC is partly compensated by a return flow to the east in the thermocline ( 150m) called the Equatorial Undercurrent (EUC). 

The equatorial undercurrent appears to be an additional source of the equatorial Pacific. 

Gordon et al. showed that in the equatorial Pacific Ocean the Fe flux is dominated by upwelling of Fe-rich Equatorial Undercurrent waters in correspondence of which a peak of concentration was observed (154). 

Equatorial Undercurrent Subsurface eastwardflowing current in the Atlantic beneath the westward-flowing Equatorial Current originally observed in 1876. 

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