Oceanography

Types of Ocean currents

Most important ocean currents are the western boundary currents and eastern boundary currents.

Western boundary currents:

• Gulf Stream
• Kuroshio
• Labrador Current
• Oyashio
• Agulhas Current
• Brazil Current
• East Australia Current

Eastern Boundary currents

• California Current

• Canary Current

• Peru Current

• Benguela Current

Indian Ocean currents

The Asiatic Monsoon influences the North Indian Ocean, while the currents of the south Indian Ocean are influenced by the atmosphere’s anticyclonic circulation. The Indian ocean currents are

1. NORTH EQUATORIAL CURRENT

            During the Northwest monsoon (February and March), the wind blows from the continent and aids in the development of the North Equatorial Current. The current flows from east to west; and upon reaching the east coast of Africa, a good portion turns southwards,  crosses the equator, and becomes the MOZAMBIQUE CURRENT. A strong counter current exists south of North Equatorial Current at this same time of year. In August and September, during the southwest monsoon, the North Equatorial Current reverses the flows west to east as the MON-SOON CURRENT. At the same time, the countercurrent seems to disappear.

2. MOZAMBIQUE CURRENT: The Mozambique Current flows south along the east coast of Africa from the vicinity of the equator to about 35⁰S, where it becomes known as the ALGUHASSTREAM.

AHULAS STREAM: The Ahulas Stream flows westward along the southern coast of Madagascar and joins the Mozambique Current along the east African coast. From there is flows south to southern tip of Africa (the Cape of Good Hope), where a good portion joins up with the West Wind Drift Current.

3. WEST WIND DRIFT CURRENT: The West Wind Drift Current flows across the Indian Ocean to the waters southwest of Australia. Here it splits; one branch continues east along the southern coast, while the other flows northward along the western coast. This branch brings relatively cool water to the western Australian coast and contributes to the formation of fog and low stratus clouds over the region.

In general, the following statements may be made concerning the effects ocean currents have on weather:

1. West Coast of continents in tropical and subtropical latitudes (except close to the equator) are bordered by cool waters. Their average temperatures are relatively low with small diurnal and annual ranges. There is fog, but generally the  areas (southern California, Morocco, etc.) are arid.

2. West coasts of continents in middle and higher latitudes are bordered by warm waters which cause a distinct marine climate. They are characterized by cool summers and relatively mild winters with a small annual range of temperatures (upper west coasts of the United States and Europe).

3. Warm currents parallel to east coasts in tropical and subtropical latitudes. This results in warm and rainy climates. These areas lie in the western margins of the subtropical anti-cyclones and are relatively unstable (Florida, the Philippines, Southeast Asia).

4. East coasts in the lower middle latitudes (leeward side) have adjacent warm waters that produce a modified continental-type climate. The winters are fairly cold, and the summers are warm or hot.

5. East coasts in the higher middle latitudes have adjacent cool ocean currents, with subsequent cool summers.