Equatorial Counter Current

The Equatorial Counter Current is an eastward surface flow between the westward North and South Equatorial Currents, found near 3 to 10 degrees north in the Atlantic and Pacific. It exists because the wind-stress curl in the doldrums band beneath the Intertropical Convergence Zone forces a return flow that opposes the trade-wind-driven westward currents, consistent with Sverdrup balance. Off the equator, the Coriolis force is large enough to support a geostrophic eastward jet. The current returns water piled up on the western side of the basins and shifts seasonally with the ITCZ.