Previous Year Question

The North Equatorial Current and the South Equatorial Current generally flow from east to west under the influence of the trade winds.

These two westward-flowing equatorial currents cause ocean water to accumulate in the western part of the ocean. The term “convergence” used in the question refers to this westward accumulation of water.

This accumulation makes the water level and water pressure in the western part of the ocean higher than in its eastern part. Consequently, a west-to-east pressure gradient develops.

The accumulated water returns towards the eastern part, where the water level is relatively lower, following this pressure gradient. This west-to-east flow is called the Equatorial Counter-Current.

The Earth’s rotation influences the direction of ocean currents, while the belt of calm near the equator provides favourable conditions for eastward flow; however, the primary cause producing the counter-current is the convergence of water in the west and the resulting pressure gradient. Difference in salinity is not its principal cause.