 | Ocean current: Encyclopedia - Ocean current
Ocean current
An ocean current is any more or less permanent or continuous, directed movement of ocean water that flows in one of the Earth's oceans.
Ocean current - Description
Ocean currents can flow for thousands of kilometers. They are very important in determining the climates of the continents, especially those regions bordering on the ocean. Perhaps the most striking example is the Gulf Stream, which makes northwest Europe much more temperate than any other region at the same latitude. Another example is the Hawaiian Islands, where the climate is somewhat cooler (sub-tropical) than the tropical latitudes in which they are located because of the California Current.
hydrothermal circulation, thermohaline circulation
Ocean current - Reasons for currents
Surface ocean currents are generally wind driven and develop their typical clockwise spirals in the northern hemisphere and counter-clockwise rotation in the southern hemisphere due to the coriolis effect. In wind driven currents the Ekman spiral effect results in the currents flowing at an angle to the driving winds. The areas of surface ocean currents move somewhat due seasons, this is most notable in equatorial currents.
Deep ocean currents are driven by density and temperature gradients. Thermohaline circulation, also known as the ocean's conveyor belt, refers to the deep ocean density-driven ocean basin currents. These currents that flow under the surface of the ocean, and are thus hidden from immediate detection, are called submarine rivers. These are currently being researched by floating devices, which maintain their depth according to slightly differing densities of waters. Upwelling and downwelling areas in the oceans are areas, where significant vertical movement of ocean water is observed.
Ocean current - Significance to man and sea life
Knowledge of surface ocean currents is essential in reducing costs of shipping, since they reduce fuel costs. In the sail-ship era knowledge was even more essential. A good example of this is the Agulhas current, which long prevented Portuguese sailors from reaching India. Even today, the round-the-world sailing competitors employ surface currents to their benefit.
Ocean currents are also very important in the dispersal of many life forms. A dramatic example is the life-cycle of the eel.
Ocean current - El Niño and La Nina
The importance of currents is also illustrated by the El Niño, in which a temporary reversal of an ocean current (La Nina) causes devastating climatic changes along the west coast of South America. Also, marine life changes significantly, and El Niño -effects have been thought to have destroyed ancient South American civilizations, most notably Moche-culture. El Niño effects spread as far as Australia.
Ocean current - Important currents:
Ocean current - Arctic Ocean
- East Greenland Current
- Norwegian Current
Ocean current - Atlantic Ocean
- Angola Current
- Antilles Current
- Benguela current
- Brazil Current
- Canary Current
- Cape Horn Current
- Caribbean Current
- East Greenland Current
- Falkland Current
- Gulf Stream
- Guinea Current
- Labrador Current
- North Atlantic Current
- North Brazil Current
- North Equatorial Current
- Norwegian Current
- Portugal Current
- South Atlantic Current
- South Equatorial Current
- Spitzbergen Current
- West Greenland Current
- West Wind Drift
Ocean current - Pacific Ocean
- Alaska Current
- Aleutian Current
- California Current
- Cromwell current (a deep current)
- East Australian Current
- Equatorial Counter Current
- Humboldt Current (or Peru Current)
- Kamchatka Current
- Kuroshio Current (or Japan Current, Kuro Siwo)
- Mindanao Current
- North Equatorial Current
- North Pacific Current (or North Pacific Drift)
- Oyashio Current (or Oya Siwo)
- South Equatorial Current
- West Wind Drift
Ocean current - Indian Ocean
- Agulhas Current
- East Madagascar Current
- Equatorial Counter Current
- Indonesian Through-flow
- Leeuwin Current
- Madagascar Current
- Mozambique Current
- Somali Current
- South Australian Counter Current
- South Equatorial Current
- Southwest and Northeast Monsoon Drift (or Indian Monsoon Current)
- West Australian Current
- West Wind Drift
Ocean current - Southern Ocean
- Antarctic Circumpolar Current
- Weddell Gyre
See also
- hydrothermal circulation
- thermohaline circulation
Other related archivesAgulhas Current, Alaska Current, Angola Current, Antarctic Circumpolar Current, Antilles Current, Arctic Ocean, Atlantic Ocean, Australia, Benguela current, Brazil Current, California Current, Canary Current, Cape Horn Current, Caribbean Current, Cromwell current, East Australian Current, East Greenland Current, East Madagascar Current, Ekman spiral, El Niño, Equatorial Counter Current, Europe, Falkland Current, Guinea Current, Gulf Stream, Hawaiian Islands, Humboldt Current, Indian Ocean, Indonesian Through-flow, Kamchatka Current, Kuroshio Current, Labrador Current, Leeuwin Current, Madagascar Current, Moche, Mozambique Current, North Atlantic Current, North Brazil Current, North Equatorial Current, North Pacific Current, Norwegian Current, Oyashio Current, Pacific Ocean, Portugal Current, South America, South Atlantic Current, South Equatorial Current, Southern Ocean, Spitzbergen Current, Thermohaline circulation, Upwelling, Weddell Gyre, West Greenland Current, West Wind Drift, climates, continents, coriolis effect, currents, downwelling, hydrothermal circulation, life-cycle of the eel, ocean basin, oceans, seasons, thermohaline circulation
 Adapted from the Wikipedia article "Ocean current", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki |
