The eastward flow of the equatorial counter-current is explained by the convergence of the two equatorial currents

The North Equatorial Current flows westward north of the equator. The South Equatorial Current flows westward south of the equator.

The convergence of these two westward-flowing currents in the equatorial region causes an upwelling of the subsurface water, resulting in the formation of the eastward-flowing equatorial counter-current.