what is a gyre

A gyre is a large system of circulating ocean surface currents, particularly those involved with large wind movements. Gyres are caused by the Coriolis effect, planetary vorticity, horizontal friction, and vertical friction. There are five major ocean gyres: the North and South Pacific Subtropical Gyres, the North and South Atlantic Subtropical Gyres, and the Indian Ocean Subtropical Gyre. These gyres are circular ocean currents formed by global wind patterns and forces created by Earths rotation. The movement of water in a gyre does not flow directly down the bulge in the center but around it due to Coriolis causing circulation around the high-pressure zone in a clockwise motion in the northern hemisphere and a counterclockwise motion in the southern hemisphere. Gyres contribute to the Geostrophic Flow of the ocean resulting in the overall Ocean circulation model of the Earth. In some instances, the term “gyre” is used to refer to the collections of plastic waste and other debris found in higher concentrations in certain parts of the ocean.