gyres

Gyres are large systems of rotating ocean currents that form under the influence of prevailing winds and the Earth's rotation. The Coriolis effect deflects moving water to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, causing large-scale circular motions.

In each major ocean basin, subtropical gyres circulate around a central area, with fast, narrow western boundary currents and slower, broad eastern boundary currents. Water is driven westward by trade winds in the tropics and by westerlies in middle latitudes, piles up in the west, and then circulates poleward along the western margin while moving equatorward along the eastern margin.

The best-known examples are the North Pacific Gyre, the North Atlantic Gyre, and the Indian Ocean Gyre. The Southern Ocean supports a circumpolar flow that connects multiple basins, while the Arctic Ocean hosts a more complex pattern influenced by sea ice and bathymetry.

Gyres distribute heat and mass across oceans, shaping regional climate, weather, and marine ecosystems. They also influence the transport and accumulation of floating debris, leading to oceanic garbage patches in some basins.

The word gyre derives from Greek gyros, meaning circle, and was adopted to describe these large-scale circular motions in geophysical fluids.