2.3.7. Currents of the Pacific Ocean
Major currents of the Pacific Ocean are:
North Equatorial Current
♤ The North Equatorial Current is a warm current which originates off the western coast of Mexico and flows in the westerly direction.
♤ It runs parallel to the equator and reaches the islands of Philippines after covering a distance of about 12,000 km.
♤ Near Philippines, under the impact of Coriolis force, it turns northwards.
♤ One branch of the North Equatorial Current flows northward to join the Kuroshio Current, while the southern branch turns eastwards to form the Counter Equatorial Current.
South Equatorial Current
♤ The South Equatorial Current is a warm current which originates due to the influence of South-east Trade winds and flows from east to west.
♤ It bifurcates into northern and southern branches near New Guinea.
♤ The northern branch turns eastward and joins the Counter Equatorial Current, while the southern branch flows along the north-eastern coast of Australia.
Kuroshio Current
♤ Kuroshio Current is an important warm current, which develops partly due to the Coriolis force and partly due to the obstruction by the Philippines in the flow of the North Equatorial Current.
♤ The average velocity is about 30 km per day and the average surface temperature is about 20°C.
♤ This current keeps the eastern coast of Japan warm even in the coldest month (January), when it is snowing heavily in Honshu and Hokkaido.
♤ A branch of Kuroshio Current enters the Sea of Japan as Tsushima Current and keeps the western coast of Japan comparatively warm.
♤ Around 35° N, the Kuroshio current comes under the impact of the Westerlies and flows in the north-east direction to reach the western coast of North America.
♤ Further northwards, it is known as the Aleutian Current.
Kurile or Oyashio Current
♤ The Kurile or Oyashio Current is a cold current which originates from the Bering Strait and moves southwards along the coast of the Kamchatka peninsula to touch the island of Kurile.
♤ It carries with it the cold water and icebergs from the Arctic Ocean to the coast of eastern Russia and Japan.
♤ Near 50° N latitude, it is bifurcated into two branches. One of them merges with Kuroshio Current and creates dense fog which is hazardous to navigation, but ideal for abundant growth of plankton.
♤ Thus the north-eastern coast of the Japanese islands is an important fishing ground in the world.
♤ The second branch moves up to the Japanese coast.
♤ The Oyashio Current is comparable to the Labrador Current of the North Atlantic Ocean.
California Current
♤ The California Currents is a cold current which flows southwards along the Pacific coastline of USA, and is comparable to the Canary Current of the Atlantic Ocean in most of its characteristics.
♤ After reaching the Mexican coast, it turns westward and merges with the North Equatorial Current.
♤ Dense sea fogs are experienced off the coast of San Francisco.
Peru Current
♤ The Peru Current is a cold current, also known as the Humboldt Current, which flows along the western coast of South America.
♤ It flows from south to north along the coast of Peru and is caused by the northward deflection of the West Wind Drift.
♤ It affects the coastal climate of Chile and Peru.
East Australian Current
♤ The East Australian Current is a warm current which is the southern branch of the South Equatorial Current, which flows from north to south along the eastern coast of Australia.
♤ New Zealand is surrounded by this current.
♤ It raises the temperature along the east Australian and the New Zealand coasts for considerable distance southwards.
West Wind Drift
♤ It is a strong, cold current, flowing from between Tasmania and South American coast.
♤ It flows under the influence of the Westerlies and is largely confined between 40° Sand 50° S latitudes.
♤ This current becomes very strong due to large volume of water and high velocity winds (Roaring Forties).
♤ One of its branch enters the Atlantic Ocean through Cape Hom, and the other branch turns northwards and joins the Peru Current.
Figure 8. Major Ocean currents
2.3.8. Currents of the Indian Ocean
The ocean currents of the Indian Ocean are largely controlled and modified by the landmasses and the Monsoon winds. The ocean currents of the North Indian Ocean flow under the influence of the north-east and the south-west Monsoon winds. Thus the ocean currents change the direction of flow twice a year.
The currents in the southern Indian Ocean follow the general pattern of other oceans and are not affected by the seasonal changes in the direction of Monsoon winds.
Major currents of the Indian Ocean are:
North-east Monsoon Current
♤ In the winter season, the north-east Monsoon winds blow from land to ocean and from the northeast to the south-west in the Northern Hemisphere.
♤ Under the influence of these winds, the ocean current also flows from the north-east to the southwest.
South-west Monsoon Current
♤ There is a complete reversat in the direction of Monsoon winds during the summer season and they blow from the south-west to the north-east in the Northern Hemisphere.
♤ This also reverses the direction of the ocean current. Now the direction of the ocean current also changes from the south-west to the northeast.
♤ Two branches of the main current move in the Arabian Sea and the Bay of Bengal.
South Equatorial Current
♤ The warm South Equatorial Current flows from east to west between 10° Sand 15° S latitudes from the western coast of Australia to the coast of Africa.
♤ After being obstructed by the Madagascar Island, this current is divided into many branches.
♤ One major branch flows towards the south as the Agulhas Current.
Agulhas Current
♤ The Agulhas Current is a warm current which is a branch of the South Equatorial Current which flows along the eastern coast of Madagascar.
♤ It continues southwards up to about 30° S, where it merges with the Mozambique Current.
♤ Around 35° S latitude, it comes under the influence of the Westerlies and flows towards the east.
Mozambique Current
♤ The Mozambique Current is a warm current which is the northern branch of the South Equatorial Current which enters the Mozambique Channel around 10° S latitude.
♤ Moving southwards between Mozambique and Madagascar, it joins the Agulhas Current around 30°S latitude.
West Wind Drift
♤ The West Australian Current is a cold current is in the southern part of the Indian Ocean and moves from west to east around 40° S latitude.
♤ The West Wind Drift develops under the influence of the Westerlies (Roaring Forties).
West Australian Current
♤ The West Australian Current is a cold current which flows along the western coast of Australia.
♤ This current turns towards west and north-west near the Tropic of Capricorn and finally merges with the South Equatorial Current.
♤ The second branch flows to the south of Australia and finally merges with the West Wind Drift in the Pacific Ocean.