Gyre

Do you know what is considered as the final destination for plastic? Well, it is Ocean Gyres. If we talk about Ocean Gyres plastic, 297 mn plastic was floating in the oceans as per the data of 2013 and it was mostly accumulated in the ocean gyres and most of the plastic in these gyres came from only ten rivers of the world. In this article, we will be learning about the ocean gyres in detail. We will learn what is gyre meaning, its various types and impacts, etc. Let's study one of the important phenomena of the ocean which helps in maintaining ocean water and influences the climate of various regions.

The continuous movement of the ocean water which is influenced by various factors such as gravity, winds, Coriolis force, density, etc. is termed as ocean currents. These movements generally occur in two directions vertically or horizontally and they are continuous in nature. They move either from the equator to the poles or from poles toward the equator. In the Northern Hemisphere, they move in the clockwise direction whereas, in the Southern hemisphere, they occur in the anti-clockwise direction. These currents are of only two types that are warm currents and cold currents. When these currents move in the circular path, they are known as ocean gyres.

Gyre Meaning

In simple words, Gyre means the movement of water in a circular motion. If we talk about the oceans, when the movement of ocean currents happen in the circular path, be it in a clockwise direction or anti-clockwise direction, this movement is known as a gyre. These ocean gyres are a combination of ocean currents that can be warm or cold and are found in all the oceans. These ocean gyres lead to having great impacts on the surroundings whereas they are influenced by majorly two factors such as Coriolis force as well as the winds. Besides these, they are also driven by temperature, salinity and other factors.

Gyre Definitions

Some of the standard definitions are given below:

• "A gyre is a circular ocean current formed by the Earth's wind patterns and the forces created by the rotation of the planet." - National Geographic

• "It is a circular or spiral motion or form, especially;  a giant circular oceanic surface current." - Merriam-Webster

• "Gyre is a circular pattern of ocean currents." - Cambridge dictionary

Major Gyres 

There are five major gyres found in the ocean which are listed below:

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North Pacific Gyre

• It is one of the major Gyres found in the ocean and it is also known as the North Pacific Subtropical Gyre which is found in the North Pacific Ocean.

• It covers most of the area of this ocean and is also considered the largest ecosystem.

• It is found in between 0° and 50° latitude and also covers around 20 mn square kilometres of area.

• It consists of four ocean currents and moves in a clockwise direction.

• The four ocean currents are North Pacific current, California current, North Equatorial current as well as Kuroshio current in north, east, south and west respectively.

South Pacific Gyre

• This is also one of the major Gyres present in the ocean and this one is present in the South Pacific.

• This is also known as South Pacific Subtropical Gyre and it moves in the anti-clockwise direction because of Coriolis force and trade winds.

• It is composed of the equator in the north, Australia in the west, Antarctic Circumpolar Current in the south, as well as South America, is seen in the east. 

North Atlantic Gyre

• This Gyre is also known as the North Atlantic Subtropical Gyre and can be seen in the North Atlantic Ocean.

• It consists of warm as well as cold ocean currents and is surrounded by North America, Africa, Europe and Iceland.

• The names of the currents it includes are Gulf stream, North Atlantic current, Canary Current and North Equatorial current in west, north, east and south respectively.

• Thermohaline circulation can be seen here, which brings saltwater from the Mediterranean Sea to the west whereas the Sargasso sea can be found in its heart where still water is found.

South Atlantic Gyre

• It is also known as the South Atlantic Subtropical Gyre present in the South Atlantic Ocean.

• It also consists of cold as well as warm currents. 

• Antarctic Circumpolar current can be found in its south which moves from West to East. It is also known as West Wind drift.

• On the western side, Brazil is the one that has the most current in this gyre.

• Besides, these South Equatorial current as well as Benguela current.

Indian Ocean Gyre

• It is also one of the important gyres found in the whole world and it is also known as the Indian Ocean Subtropical Gyre.

• It is located in the Indian Ocean which consists of a larger number of ocean currents.

• The two major currents of this gyre are South Equatorial Current as well as West Australian Current.

• Generally, in winters it moves in the anti-clockwise direction but it is reversed because of the influence of South Asian Monsoon winds.

• This Gyre plays a vital role in the surrounding environment and geography. 

Types of Other Ocean Gyres

There are three other main types of gyres present in the Ocean. The names of the gyres are tropical, subtropical and subpolar.

Tropical Gyres

These types of Gyres are less unified and generally tend towards the east to the west whereas minor north-south extent can also be observed. Examples of such gyres can be the Atlantic Equatorial Current system, Pacific Equatorial Current system, and Indian Monsoon Gyres. These all currents are present near the equator or in between the tropical ranges.

Subtropical Gyres 

The centre of this gyre consists of high pressure and in the Northern Hemisphere, the circulation occurs in a clockwise direction whereas, in the Southern hemisphere, it occurs in the anticlockwise direction because of the presence of Coriolis force. These currents present in the subtropical regions and the water build-up at the centre here makes a flow towards the equator and this flow again returned towards the poles in the form of western boundary currents which are intensified such as the Gulf stream is the boundary current of North Atlantic gyre and the Kuroshio current works as the boundary current of the North Pacific Gyre, similarly the Brazil current works as the boundary current of South Atlantic Gyre whereas East Australian current is of the South Pacific Gyre and the Agulhas current works as boundary current of the Indian Ocean Gyre.

Subpolar Gyre

These gyre forms at higher latitudes ie. around 60° or we can say in the subpolar regions. In the Northern Hemisphere, anti-clockwise circulation around the low pressure can be seen at the surface wind as well as ocean water. This surface current usually moves in the outward direction from the centre and leads to the upwelling of the nutrients and resources-rich water from the lower depth of the ocean water. In the Southern hemisphere, the Antarctic Circumpolar current dominates the subpolar circulation here. Minor Gyres can be seen here such as Weddell Gyre as well as Ross Gyre which moves in the clockwise direction.

Gyres in Ocean - Map

The presence of warm and cold currents can be seen in the following maps and thus the formation of ocean Gyres as well in the circular format can also be observed. Here, the red arrows indicate the warm currents whereas the blue arrows indicate the cold currents.

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Impacts

Ocean Gyres are made up of ocean Gyres which cause great impacts on the oceans and their surroundings. This current not only flows above the ocean water but also below the ocean surface. The Ocean Gyres are present in almost all the major oceans where water moves from poles to the equator and then from the equator towards the poles. This circular motion is influenced by several factors whereas these ocean gyres lead to imposing great impacts on the climate of the surrounding areas. It also helps in the upwelling of nutrients and resource-rich deep water up to the surface which helps in the feeding of marine organisms. It also helps in maintaining the temperature, the salinity of different areas as thermohaline circulation can be observed here. It also takes moisture and warmness from the equator towards the higher latitudes and also influences the temperature as well as the rainfall patterns. 

Conclusion

Thus, we can conclude that Ocean gyres are circular movements in the ocean water that can be observed in all the oceans which helps in maintaining the water of the oceans and also leads to having impacts on the continents. Majorly five main gyres can be seen on the Earth along with other minor gyres. This is one of the most important topics of Oceanography which plays a vital role in the oceans and continents as well as the weather conditions. This topic will be helpful in Oceanography and Geography or Earth Sciences and Geology as well. 

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