[Geography Notes] on Ocean Current Pdf for Exam

Among the various extraordinary incidences that the earth hosts, ocean current is one. It is the seawater movement directionally and continuously influenced by gravity, the Coriolis Effect of the wind, and the density of water. Now the ocean current can show two directional movements- horizontal and vertical. The former is termed as “current” while the latter is termed as “upwelling” or “downwelling.” Ocean currents, a part of the abiotic system of the environment, contribute to the transfer of heat, bringing in biodiversity variations and also develop the global climate system.

What are the Types of Ocean Currents?

Broadly, as ocean currents UPSC syllabus determines, the ocean currents are of two types- warm and cold. Equator regions carry the warm ocean currents while cold currents originate from the Polar Regions. Based on the strength of the flow, the currents can be of two more types. Western boundary currents are the ones with strong and fast currents, whereas Eastern boundary currents are the ones with comparatively shallow and moderate strength of the currents. 

What is Thermohaline Circulation?

Thermohaline circulation, or THC, is a part of the ocean circulation where the density gradient of the ocean water plays a pivotal role. The difference in density is caused by the flow of freshwater and the surface heat. It is the temperature and the salt content of the water that gives rise to the different density of the seawater leading to the name “thermohaline,” where thermo refers to temperature and haline refers to the salt content. 

What is Agulhas Current?

Agulhas current, a warm current, is formed by the merging of Mozambique and Madagascar current. This current continues southwards till it meets the Northwesterly wind. It increases temperature along the east coast of South Africa. 

What is Kuroshio Current?

Yet another warm ocean current, the Kuroshio Current, flows from Taiwan to the Bering Strait. It is also known as the Japan current or the Black current, or the Black stream. It is generally found on the west side of the North Pacific Ocean. Being a western boundary current, this type of wind is quite powerful. 

What is Gulf Stream Current?

One of the strong ocean currents, the Gulf Stream, is responsible for bringing warm water into the Atlantic Ocean from the Gulf of Mexico. The eastern coasts of Canada and the United States is the region where this current extends. Oceanic gyre is the main reason behind its formation. Gyres are a system consisting of powerful winds and a series of circular currents. One such gyre is the North Atlantic Subtropical Gyre, of which the Gulf Stream Current is a part. As the Gulf Stream brings in the warm water, the cold water already existing in the Atlantic Ocean is forced to move south as it is denser. Ultimately the cold water flows to Antarctica.

What is Oyashio Current?

It is one of the cold ocean currents. The Kamchatka current flows along the Kamchatka peninsula from Bering Strait in SW direction. This later form Oyashio Current and some of its parts join the North Pacific Current. The water that Oyashio Current carries comes from the Arctic Ocean and continues to flow along south through the Bering Sea. Along the way, it comes across the Kuroshio Current around the Eastern Japan shore and together forms one of the Pacific Ocean currents, namely North Pacific Current. The current brings cold water from the Arctic sea into the Pacific Ocean. 

What are Equatorial Currents?

There are two types of Equatorial currents- north and south. The brief details of these currents are as follows:

1. North Equatorial Currents: 

This current originates from the western coast of Mexico and flows in a westerly direction. California current and NE monsoon is responsible for the formation of this current. It carries warm water towards Alaska.

2. South Equatorial Currents: 

This originates due to the influence of SE trade winds and flows from East to West. Then it gets bifurcated near New Guinea into the Northern and Southern Branch. The first one turns eastward and flows as a counter equatorial current, and the latter moves into the north direction along the NE coast of Australia.

What is Humboldt Current?

This current is the continuation of west Wind drift from the Antarctic that flows northwards along the western coast of South America. It is associated with the El-Nino effect in South America. It also affects the timely arrival of the Indian monsoon.

What are Labrador and Benguela Currents?

Labrador current originates in the Baffin Bay and the Davis Strait and moves eastward, merging with Gulf Stream near Newfoundland. Its confluence with Gulf Stream produces heavy fog along the coast of Newfoundland, a vital fishing ground globally, such as as- Grand Bank, Dogger Bank, George Bank.

Benguela Current flows from south to north along the western coast of South Africa and merges with the South Equatorial current. It leads to foggy conditions along the coast of Namibia. This particular current helped in the development of the Namibian and Kalahari Desert.

Did you know?

• Rotation of the earth creates oceanic water to bulge out. 

• Currents move clockwise in the northern hemisphere, whereas in the southern hemisphere, left deflection currents lead the counterclockwise movements.

• Western Boundary Currents lack nutrients and thus contain sterile water.

• Eastern boundary currents do not have well-defined boundaries.