[General Geog] Ocean Currents

Ocean Currents

The general movement of a mass of oceanic water in a definite direction is called as “Ocean Currents”

 Classifications of Ocean Currents

 (01) On the basis of temperature

à Warm Currents: carry warm water away from North and South poles

(Those that flow from equatorial regions polewards have a higher surface temperature and is called as warm currents)

à Cold Currents: carry cold water away from North and South poles

(Those that flow from equatorial regions equatorwards have a lower surface temperature and is called as cold currents)

 (02) On the basis of velocity, dimension and direction

àDrifts: The forward movement of surface water of the oceans under the influence of prevailing winds

à Currents: Involves the movement of oceanic water in a definite direction with greater velocity

à Streams: Involves movement of larger mass of ocean water like big rivers of the continent in a definite direction with greater velocity than drifts.

          The direction of ocean currents is determined and detected by:

(i) prevailing winds

(ii) earth rotation

(iii) configuration of coastlines and

(iv) bottom reliefs of the oceans.

Generally, warm current is represented by solid line with arrow mark at the end (à) and 

cold current is represented by dashed line with arrow mark at the end (- - ->)

Effects of Ocean Currents:

i) Modification in the coastal climate

ii) Effects on fishing

iii) Effects on trade and navigation

Major Currents:

#	Current	Type	Ocean
1	North Equatorial	Warm	Atlantic Ocean
2	South Equatorial	Warm
3	Counter-Equatorial Current	Warm
4	Gulf Stream	Warm
5	Brazil	Warm
6	Canary	Cold
7	Labrador	Cold
8	Falkland	Cold
9	South Atlantic Drift	Cold
10	Benguela Current	Cold
11	North Equatorial	Warm	Pacific Ocean
12	South Equatorial	Warm
13	Counter Equatorial	Warm
14	Kuroshio System	Warm
15	East Australia	Warm
16	Oyashio	Cold
17	California	Cold
18	Peru	Cold
19	West Wind Drift	Cold
20	North East Monsoon	Warm	Indian Ocean
21	South West Monsoon	Warm
22	Indian Counter	Warm
23	Indian Equatorial	Warm
24	Mozambique	Warm
25	West Wind drift	Cold

Currents of Atlantic Ocean:

#	Current	Type	Flows from	Deflection
1	North Equatorial	Warm	East to West	i) Antilles Current ii) Caribbean Current Caribbean current enters the Gulf of Mexico and becomes Gulf Stream Antilles Current diverted Northward and flows to east of West Indies islands and helps in formation of ‘Sargaosso Sea’
2	South Equatorial	Warm	West to East (South America)	i) Northward branch merges with North Equatorial Current near Trinidad ii) Second branch turns southward and continues as Brazil Warm Current
3	Counter-Equatorial Current	Warm	West to East	This current mixes with the equatorial currents in the West but it is more developed in East where it is known as Guinea Stream
4	Gulf Stream	Warm	North-Easterly	The Gulf Stream system largely modifies the weather conditions of the eastern coasts of the USAand the western coasts of Europe. Gulf Stream is responsible for unique characteristics of West European Type of Climate. i) Florida Current ii) Gulf Stream iii) North Atlantic Drift Current
The origin of the Florida Current is attributed to the piling up of immense volume of water in the Gulf of Mexico due to powerful Trade Winds. Florida Current is the northward extension of the North Equatorial Current. Florida Current is joined by the Antilles Current. Gulf Stream: The Florida Current after having the water of Antilles current is known as Gulf Stream North Atlantic Drift Current: 3 major types and 7 sub types of currents
5	Brazil	Warm
6	Canary	Cold	Western Coast of North Africa
7	Labrador	Cold		This current brings with it a large number of big icebergs as far south as Newfoundland and Grand Bank. Dense fogs are also produced due to the convergence of Labrador cold current and the Gulf Stream near New Foundland
8	Falkland	Cold	South to North	This current brings numerous icebergs from the Antarctic area to the South American coast
9	South Atlantic Drift	Cold		Eastward continuation of South Atlantic Drift. Also known as Westerlies Drift or the Antarctic Drift
10	Benguela Current	Cold	South to North	This current merges with South Equatorial Current

Currents of Pacific Ocean:

#	Current	Type	Flows from	Deflection
01	North Equatorial	Warm	Flows in westerly
02	South Equatorial	Warm	East to West
03	Counter Equatorial	Warm	West to East
04	Kuroshio System	Warm	East to West	i) Kuroshio current ii) Kuroshio Extension iii) North Pacific Drift iv) Tsushima current v) Counter Kuroshio current
05	East Australia	Warm	North to South	It raises the temperature of east Australian coast
06	Oyashio	Cold	Flows in southerly	Also known as Kurile Cold Current The convergence of Oyashio current and Kuroshio current causes dense fogs which becomes potential hazardous for navigation
07	California	Cold	Flows in eastward
08	Peru	Cold	South to North in western coast of South America	Also called as Humboldt Current
09	West Wind Drift	Cold	West to East	One branch enters the Atlantic Ocean through Cape Horn while the second branch turns southward and joins Peru Current

Currents of Indian Ocean:

          The current systems of the Indian ocean are largely controlled and modified by landmasses and monsoon winds. Indian Ocean being surrounded by the Indian subcontinent, Africa and Australia does not present most favourable conditions for the development of permanent and consistent system of ocean currents. The current sin the northern Indian Ocean change their flow direction twice a year due to north-east and south-west monsoon winds.

#	Current	Type	Flows	Deflections
01	North East Monsoon	Warm	From land to ocean during winter season in Northern Hemisphere
02	South West Monsoon	Warm	South west to north east
03	Indian Counter	Warm	Easterly
04	Indian Equatorial	Warm	East to West	i) southward deflection is called as Agulhas Current (warm)
05	Mozambique	Warm	East o West
06	West Wind drift	Cold	Westerly

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