Equatorial Ekman transport creating a low pressure zone at the surface of the ocean, which is filled by colder upwelling water from deeper in the ocean.

Surface winds from due North and due South blowing towards the equator from the North and South Poles, blowing cold surface water towards the equator. At the Equator this cold water has nowhere else to go, so it stays there as a cold band.

Icebergs from Antarctica, which are caught up in the Southern Hemisphere Ekman spiral, and drift northwards to melt at this location, resulting in a cold zone in the Pacific Ocean.

Meltwater from glaciers on equatorial mountains in South America, flowing down rivers into the Pacific Ocean at that location, resulting in a cold zone in the Pacific Ocean.

Equatorial Ekman transport creating a topographic high zone at the surface of the ocean, which is then cooled, as temperature decreases with elevation.