Explanation:

The equatorial countercurrents are driven by a distinct surface wind pattern in the tropics. Strong westward trade winds result in westward surface flow in most of the tropical Atlantic and Pacific Oceans. However, several hundred kilometers north of the equator the winds are much weaker, in comparison.
The stronger winds to the south pile up water where the winds are weak. As a result, the surface of the ocean can be up to 6 in. (15 cm.) higher and the thermocline (region of strongest decrease of temperature with increasing depth) as much as 328 ft. (100 m.) deeper than it is directly to the north. The excess water flows eastward under the influence of the Earth’s rotation, giving rise to the equatorial countercurrents.