What explains the eastward flow of the equatorial counter-current?

Question

Accepted Answer

The easterly Equatorial Counter-Current between about 4° and 10° N may be explained as follows:The overall effect of the Trade Winds is to drive water towards the west, but the flow is blocked by the land masses along the western boundaries. As a result, in equatorial regions the sea-surface slopes up towards the west, causing an eastward horizontal pressure gradient force.Because winds are light in the Doldrums, water is able to flow down the horizontal pressure gradient in a current that is contrary (i.e. 'counter') to the prevailing wind direction. The zone of calm is the necessary and dominant factor here, though other factors play their role as well.