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Ocean Currents
geography for NDA
Ocean Currents :
- An ocean current is a continuous, directed movement of ocean water generated by the forces acting upon it, such as breaking waves, wind, coriolis effect, temperature and salinity differences and tides caused by the gravitation pull of the Moon and the Sun.
- Ocean currents circulate in clockwise direction in Northern hemisphere and in anti clockwise direction in Southern hemisphere.
- Warm Currents The ocean currents flowing from lower latitude to higher latitude are known as Warm Currents.
- Cold Currents The ocean currents flowing from higher latitude to lower latitude are known as Cold Currents.
- At places where cold current and warm current meets fishing is very favourable. e.g. New found land is favourable for fishing due to meeting of Labrador Current and North Atlantic Drift.
Currents of North Pacific Ocean
Warm Currents- North Equatorial Current It flows Westwards from the Western coast of Mexico to the Philippines.
- Kuroshio Current It is an extension of North Equatorial Current near Japan Coast. It flows towards North.
- Alaska Current It flows along the coast of British Columbia and the Alaska Peninsula.
Cold Currents
- Oyashio Current It flows down from bering sea towards Japan from North pole and it joins Kuroshio currents.
- Okhotsk Current and Kuril Current It flows down from sea of Okhotsk and joins Kuroshio current to the North of Japan.
- West Wind Drift It flows towards Alaska.
- Californian Current It is an extension of Alaskan currents. It joins finally North Equatorial current and completes clockwise circulation of water.
Currents of South Pacific Ocean
Warm Currents
- East Australian Current or Great Barrier Current It flows towards East coast of Australia from equator towards Pole.
- South Equatorial Current It originates due to South-East trade winds and flows Westwards and bifurcates near New Guinea.
- Counter Equatorial Current It extends upto Panama Bay. It flows exactly on equator from West to East.
Cold Currents
Peruvian Current (Humboldt current) It flows from South towards equator on the coast of Chile and Peru.West Wind Drift It flows from Tasmania to Chile coast of South America.
Currents of North Atlantic Ocean
Warm Currents
- North Equatorial Current It is present between Equator and 10°N.
- Cayenne Current It flows adjacent to French Guinea and enters into Carribean Sea and Gulf of Mexico.
- Florida Current Cayenne current near Florida (US Coast) is called Florida Current.
- Antilles Current It flows to the East of West Indies and other islands.
- Gulf Stream It flows from US coast towards North West Europe under the influence of Westerly winds.
- North Atlantic Drift Gulf Stream bifurcates into
West Wind Drift (cold) and Canaries current (cold).
Cold Currents
- Labrador Current It orginates in Baffin Bay and Davis Strait and merges with Gulf Stream near Newfoundland. Newfoundland is a famous zone of fishing, commonly known as Grand Bank.
- Irminger Current or Greenland Current It flows between Greenland and Iceland and merges with North Atlantic drift.
- Canaries Current It flows along the Western coast of North Africa between Madeira Cape Verde and it joins North equatorial current.
- West Wind Drift It flows clockwise from West to East around Antarctica.
Currents of South Atlantic Ocean
Warm Currents
- South Equatorial Current It flows between equator and 10°S.
- Brazilian Current It flows to the East coast of Brazil from equator towards pole.
Cold Currents
- Falkland Current It flows along the South-East coast of South America from South to North,
- Benguela Current It flows from South to North near the Cape of Good Hope'.
- West Wind Drift It is continuance of Brazilian and Falkland current.
- Guinea Current It flows near Coast of Guinea (Africa).
Current of the Indian Ocean
- The Asiatic Monsoon influences the currents of the North Indian Ocean, while the currents of South Indian ocean are influenced by the atmosphere's anticyclonic circulation.
- North Equatorial Current The current flows from East to West and upon reaching the East coast of Africa, a good portion turns Southward, crosses the equator and becomes the Mozambique current.
- Mozambique Current The Mozambique current flows South along the East coast of Africa from the vicinity of the equator to about 35°, where it becomes Agulhas Stream.
- Agulhas Stream The Agulhas stream flows Westward along the South-West of Madagascar and joins the Mozambique current along the East African coast.
- West Wind Drift Current It flows across the Indian ocean to the waters South-West of Australia.
- North-East Monsoon Drift It flows along the coast of India during winter.
- South-West Monsoon Drift It flows along the coast of India during Summer.
- South Equatorial Current It is a significant Pacific, Atlantic and Indian ocean current that flows East-West between the equator and about 20° South.
- Somalia Current It is an ocean boundary current that runs along the coast of Somalia and Aman in the Western Indian ocean and is analogous to the Gulf Stream in the Atlantic Ocean.
EL Nino and La-Nina
- EL Nino and La Nino are opposite phases of what is known as the EL Nino-Southern Oscillation (ENSO) cycle. The ENSO cycle is a scientific term that describes the fluctuation in temperature between the ocean and the atmosphere in East-Central Equatorial Pacific.
- EL Nino is considered as the warm phase of ENSO and La Nina is refered to as the cold phase of ENSO. These deviations from normal surface temperatures can have large-scale impacts not only on ocean processes but also on global weather and climate.
EL Nino
- It means “The Little Boy' or 'Christ Boy' in Spanish. It was originally recognised by fishermen off the coast of South America in 1600s, with the appearance of usually warm water in the Pacific Ocean.
- The effects of EL Nino have been seen over North America during the upcoming winter season. Those Western and Central Canada and over the Western and Northern USA.
La Nina
- It means "The Little Girl'. It presents a situation that can be described as roughly opposite of EL Nino.
- During the occurance of this condition sea surface temperature in the central and western
- the normal and this happens due to the South pacific sub-tropical high becoming exceptionally strong during the pacific falls below summer season.
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