Ocean Circulation

Ocean currents help to maintain the Earth’s heat balanceSouth Equatorial Current by advecting heat from the tropics to polar latitudesEquatorial CurrentsSouth. The trade windsEl Niñoand trade winds drive the North and South Equatorial CurrentsCurrentsHumboldtSouth Equatorial Current in the Northern and Southern HemisphereSouthern Hemisphere, respectively, flowing from east to west and forming the backbone of surface ocean circulation. The Coriolis effectCoriolis effect bends the winds, which drags the surface ocean currentsOcean currents (see currents) and produces anticyclonic gyres—large, permanent, ocean basin-wide circulations steered around the subtropical anticyclones in the mid-latitude ocean basins. Other spin-offs of the gyres and non-gyre-related regional surface currents are important components of the oceanic circulation as well. The Equatorial Counter-currents move water from west to east. MesoscaleMesoscale ocean eddies are secondary rather than general circulation features, akin to mid-latitude wave cyclones in the atmosphereAtmosphere, as they are embedded within broader-scale circulation. The Ekman spiral causes ecologically and climatologically important upwellingEl Niñoand upwelling in many coastal locations where the surface water is pushed oceanward. All of these circulations are connected, from the surface to the depths, by a prevailing three-dimensional conveyor belt of oceanic general circulation known as the global thermohaline circulation that moves in a predictable pattern. The oceans have many other effects on the atmospheric circulation.