Cold core ring

Mesoscale eddies are usually seen in areas of intense, meandering currents such as the Gulf Stream and the Antarctic Circumpolar Current that feeds into the South Pacific and Indian oceans, but in general can be caused by a combination of factors such as cooling of sea surface temperature, convection, direct generation from wind, or water flow past an irregular or jagged coastline.

[2] Cyclonic cold-core eddies are frequently formed at the polar front by the Gulf Stream and Labrador Current.

[3] The cold, nutrient-rich waters from the Labrador Sea flow south and get caught in the eastward meandering of the Gulf Stream, traveling east across the Atlantic Ocean.

[5] Some permanent eddies are regular enough to be given names within the ocean current system such as the cold-core Agulhas Ring off the tip of South Africa.

[7] Despite being surrounded by the highly saline and generally nutrient devoid waters of areas in the middle of oceanic gyres, cold core rings, especially those found in the Sargasso sea from the gulf stream, as mentioned before, have the ability to transport the nutrients and biota of the colder regions from which they originated into the warmer regions into which they travel.

This makes them ideal locations for primary productivity, especially in areas of low nutrients, such as the center of open ocean gyres,[2] such as the Sargasso sea.

An image depicting the formation of eddies as a closed off meander and a cold core ring.
The meanders of the gulf stream can form eddies. The image depicts a cold core ring as well as a meander of the gulf stream in the process of forming a cold core ring.
Zooplankton are frequently influenced and displaced by the course of cold core rings.