The characteristics of the currents of the Indian Ocean are quite different from those of Pacific and Atlantic Oceans. This is due to the fact that it is just half an ocean and is completely land-locked in the north. The currents of the northern Indian Ocean change their direction due to seasonal changes in the direction of the monsoons. The current affected by monsoons is known as the “Monsoon Drift”.
The southern part of the Indian Ocean extends right up to the Antarctic Coast and is not influenced by seasonal changes. The general pattern of circulation is simple and is anti-clockwise like that of the other southern oceans.
Currents of the North Indian Ocean
The currents of the North Indian Ocean can best be studied with reference to seasonal changes:
Winter Conditions
In winter, the north equatorial current is under the influence of the north-east monsoon and blows from east to west. This is known as the North-East Monsoon Drift. It starts from the Strait of Malacca and flows along the coast of the Bay of Bengal. After crossing Sri Lanka, it flows along the coast of the Arabian Sea and turns southwards. From there it travels from west to east as the Counter Equatorial Current and completes the anticlockwise circulation.
Summer Season
During summer, a strong current flows from west to east which completely obliterates the North Equatorial Current during this season. It is due to the effects of the strong south-west monsoon and the absence of the North-East Trades. There is no Counter Equatorial Current at this time of year. Thus, the circulation of water in the northern part of the ocean is clockwise during this season.
Currents of the South Indian Ocean
The circulation of currents of the South Indian Ocean is similar to that of the South Pacific and South Atlantic Oceans. The following scheme explains these currents:
South Equatorial Current
Like other oceans, the Indian Ocean has a south equatorial current flowing parallel to the equator from east to west.
Mozambique Current
The South Equatorial Current divides itself into two branches on reaching Madagascar. One of them flows through the Mozambique Channel between Mozambique and Madagascar coasts. This is a warm current and is known as the warm Mozambique Current.
Madagascar Current
The other branch of the South Equatorial Current flows along the east coast of Madagascar and is known as the Madagascar Current.
Agulhas Current
In the south of Madagascar Island, the Mozambique and Madagascar Currents join with each other. After the confluence of these two currents, it is known as the Agulhas Current. It still continues to be a warm current till it merges with the West Wind Drift.
West Wind Drift
The West Wind Drift is a cold current which flows from west to east and reaches the southern tip of the west coast of Australia.
West Australian Current
On reaching Australia, the West Wind Drift divides into two branches. One of the branches moves northwards along the west coast of Australia and is known as the West Australian Current. It ultimately joins the South Equatorial Current and completes the counter clockwise circuit in the South Indian Ocean.
