Oceans Submarine Relief and Water Circulation: Currents of The Pacific Ocean, Currents of the Indian Ocean

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Currents of the Pacific Ocean

  • In the Equatorial belt of the Pacific Ocean, two streams of equatorial currents flow across the ocean from the Central American Coast. Between these two, the North Equatorial Current and the South Equatorial Current flows a Counter Educational current moves west to east. The North Equatorial Current turns northwards and flows along the Philippines Islands, Taiwan and Japan to form the warm Kuroshio Current.

  • From the southeast coast of Japan, the current comes under the influence of westerlies and flows right across the ocean as North Pacific Current. After reaching the west coast of North America, its northern branch flows anti clockwise along the coast of British Columbia and Alaska as the Alaska Current. The other branch moves southward along the coast of California as the Cold Californian Current. It eventually joins the North Equatorial Current to complete its circuit. In the northern part of the Pacific Ocean two cold currents flow. The cold Oya Siwo Current flows along the coast of the Kamchatka Peninsula and the Okhotsk Current flows past Sakhalin to merge with the Oya Siwo Current near Hokkaido Island.

Surface Currents of the Pacific Ocean

Surface Currents of the Pacific Ocean

In the South Pacific Ocean, the South Equatorial Current flows towards west and turns southwards as the East Australian Current. On reaching the south western coasts of South America, the cold South Pacific Current turns north wards as the cold Peru Current. It then meets the South Equatorial Current and completes the circuit.

Currents of the Indian Ocean

  • The general pattern of circulation in the southern section of the Indian Ocean is anti-clockwise as that of other oceans. But in the northern section, there is a clear reversal of currents in winter and summer. These are completely under the influence of the seasonal changes of the monsoon winds. There is a clear reversal of currents in the winter and summer season i.e., south westwards during the north-east Monsoon, north-eastwards during the southwest Monsoon, and variable during transition season.

  • During winters Sri Lanka divides the currents of the Arabian Sea from those of the Bay of Bengal. The North Equatorial Current flows westward south of Sri Lanka with distinct counter equatorial current flows between it and the South Equatorial Current. The north-east Monsoon drives the water of Bay of Bengal and Arabian Sea west wards to circulate in an anti-clockwise direction. This current is known as North East Monsoon Drift.

Indian Ocean During Winter and During Summer

Indian Ocean During Winter and During Summer

  • In summers, the northern section comes under the influences of South West Monsoon. There is an easterly movement of water in the Bay of Bengal and Arabian Sea and produces a clockwise circulation. This current is known as South West Monsoon Drift.

  • In the southern Indian Ocean, the South Equatorial Current, strengthened by its corresponding current of the Pacific Ocean, flows from east to west. It turns southwards along the Coast of Mozambique in Africa. A part of this current which flows between the mainland and the Madagascar Island is known as warm Mozambique Current. After the confluence of these two currents, it is called Aghulas Current. It then turns eastwards and merges with the West Wind Drift. A branch of West Wind Drift turns north to flow along the western coast of Australia as cold West Australian Current. West Australian Current later joins the South Equatorial Current to complete the circuit.

Effects of Ocean Currents

Influence on Climate

  • Oceans currents closely influence the distribution of temperature, pressure, winds and precipitation, which directly or indirectly influence the economy and society of the people, especially those living in the coastal regions.

  • Currents move from warm temperature areas to colder temperature areas and vice versa. As they move from one place to another, they partly modify the temperature. The ocean current that moves from the equatorial region to the colder latitudes raises the temperature of the air in the areas into which it moves. For example, warm North Atlantic Drift which flows northwards to West European coast keep the coast of Great Britain and Norway free of ice in winter too. The effect of the ocean current becomes evident if we compare the winter conditions of the British Isles with that of the northeast Coast of Canada situated on the same latitudes. The north east Coast of Canada comes under the influence of cold Labrador current, and remains ice bound during the wintertime.

  • When cold and warm currents meet, they produce mist and fog. Near Newfoundland, warm Gulf Stream meets Labrador Current and produces fog. They also create conditions for storms. Hurricanes in Newfoundland and Typhoons in Japan are the result of the meeting of warm and cold currents.

Influence on Marine Life

The areas where warm and cold currents meet are among the most important fishing grounds of the world. The oceanic movement in the form of currents helps in the dispersal of marine life.

Influence on Trade

The ports and harbours of higher latitudes which are affected by warm currents are ice free and open for trade all the year round. For instance, the ports of north-western Europe remain open throughout the year while the port of Quebec in Canada gets frozen in winters.

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