What is a subtropical gyre?

A subtropical gyre is a vast, circular system of ocean currents spiraling around a central point, situated beneath a subtropical high-pressure region. Driven by wind, these anticyclonic areas cause surface water to sink, leading to subtropical convergence around 20°–30° latitude. These gyres have westward intensification due to the increasing Coriolis force with latitude. This causes the western boundary current to be a fast current that moves heat from low to high latitudes. In contrast, the flow on the inside and eastern boundary is a slow drift of cooler water, often causing coastal upwelling. Examples include the Gulf Stream in the North Atlantic and the Kuroshio Current in the North Pacific.

Where are subtropical gyres found in the ocean?

Subtropical gyres, characterized by anticyclonic ocean circulation, are found beneath subtropical high-pressure regions, typically around 20°–30° latitude. These gyres exist in each of the major ocean basins. The strongest western boundary current among these gyres is the Gulf Stream in the North Atlantic Ocean. Other notable western boundary currents include the Kuroshio Current in the North Pacific, which closely resembles the Gulf Stream, as well as the Brazil and East Australian currents, though they are relatively weaker. The Agulhas Current in the Indian Ocean has a transport capacity similar to the Gulf Stream. Additionally, a steady subtropical anticyclonic gyre exists south of the monsoon region in the Indian Ocean .

How are subtropical gyres formed?

Subtropical gyres are vast, rotating ocean current systems that spiral around a central point. They form beneath subtropical high-pressure regions. Ekman transport causes surface water to sink, creating subtropical convergence around 20°–30° latitude. The westward intensification of currents in these gyres results from the increase of the horizontal Coriolis force with latitude. This causes the poleward-flowing western boundary current to be a fast, jet-like current, transporting heat from low to high latitudes. In contrast, the equatorward-flowing interior and eastern boundary have a slow drift of cooler water. Coastal upwelling also occurs due to offshore Ekman transport.

What currents are part of a subtropical gyre?

Subtropical gyres are anticyclonic circulation features that extend from the equatorial current system to the maximum westerlies in a wind field near 50° latitude. These gyres have western boundary currents such as the Gulf Stream in the North Atlantic Ocean, which is known as the strongest of these currents, and the Kuroshio current of the North Pacific. Others include the Brazil Current, the East Australian Current, and the Agulhas Current. The movement of water within the Ekman layer forces surface water to sink, creating the subtropical convergence near 20°–30° latitude.

How do subtropical gyres affect global climate?

Subtropical gyres are vast, circular systems of ocean currents spiraling around a central point, situated beneath subtropical high-pressure regions. The movement of water in these gyres causes surface water to sink, leading to the subtropical convergence around 20°–30° latitude. These gyres play a role in global climate by transporting heat from low to high latitudes. The Gulf Stream in the North Atlantic, a strong western boundary current, moves approximately 30 million cubic meters of water per second through the Florida Straits. The heat released from the Norwegian Current , part of the North Atlantic subpolar gyre, helps maintain a moderate climate in Northern Europe.

Why are subtropical gyres important for ocean life and ecosystems?

Subtropical gyres are significant to ocean life and ecosystems because they are large rotating ocean currents that influence the distribution of marine organisms and play a role in ocean health. These gyres can determine the range of a species and transport marine life over great distances. For example, the Gulf Stream and East Australian Current carry larvae to cold temperate coral reefs, and eels rely on the Gulf Stream to travel from Caribbean spawning sites to Europe. However, subtropical gyres can also accumulate plastic pollution , which poses a threat to marine life through entanglement and ingestion. Plastics can also concentrate pollutants and deliver them to species that ingest them, disrupting food chains and potentially leading to extinctions.

subtropical gyre

Introduction References & Edit History Related Topics

Quick Facts

Related Topics:: gyre

See all related content

subtropical gyre

oceanography

Written and fact-checked by

Britannica Editors

History

Top Questions

What is a subtropical gyre?
A subtropical gyre is a vast, circular system of ocean currents spiraling around a central point, situated beneath a subtropical high-pressure region. Driven by wind, these anticyclonic areas cause surface water to sink, leading to subtropical convergence around 20°–30° latitude.

These gyres have westward intensification due to the increasing Coriolis force with latitude. This causes the western boundary current to be a fast current that moves heat from low to high latitudes. In contrast, the flow on the inside and eastern boundary is a slow drift of cooler water, often causing coastal upwelling. Examples include the Gulf Stream in the North Atlantic and the Kuroshio Current in the North Pacific.
4 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Where are subtropical gyres found in the ocean?
Subtropical gyres, characterized by anticyclonic ocean circulation, are found beneath subtropical high-pressure regions, typically around 20°–30° latitude. These gyres exist in each of the major ocean basins.

The strongest western boundary current among these gyres is the Gulf Stream in the North Atlantic Ocean. Other notable western boundary currents include the Kuroshio Current in the North Pacific, which closely resembles the Gulf Stream, as well as the Brazil and East Australian currents, though they are relatively weaker. The Agulhas Current in the Indian Ocean has a transport capacity similar to the Gulf Stream. Additionally, a steady subtropical anticyclonic gyre exists south of the monsoon region in the Indian Ocean.
4 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How are subtropical gyres formed?
Subtropical gyres are vast, rotating ocean current systems that spiral around a central point. They form beneath subtropical high-pressure regions. Ekman transport causes surface water to sink, creating subtropical convergence around 20°–30° latitude.

The westward intensification of currents in these gyres results from the increase of the horizontal Coriolis force with latitude. This causes the poleward-flowing western boundary current to be a fast, jet-like current, transporting heat from low to high latitudes. In contrast, the equatorward-flowing interior and eastern boundary have a slow drift of cooler water. Coastal upwelling also occurs due to offshore Ekman transport.
5 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What currents are part of a subtropical gyre?
Subtropical gyres are anticyclonic circulation features that extend from the equatorial current system to the maximum westerlies in a wind field near 50° latitude.

These gyres have western boundary currents such as the Gulf Stream in the North Atlantic Ocean, which is known as the strongest of these currents, and the Kuroshio current of the North Pacific. Others include the Brazil Current, the East Australian Current, and the Agulhas Current.

The movement of water within the Ekman layer forces surface water to sink, creating the subtropical convergence near 20°–30° latitude.
2 Britannica Sources
1. subtropical gyre
2. ocean current: The subpolar gyres
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How do subtropical gyres affect global climate?
Subtropical gyres are vast, circular systems of ocean currents spiraling around a central point, situated beneath subtropical high-pressure regions. The movement of water in these gyres causes surface water to sink, leading to the subtropical convergence around 20°–30° latitude.

These gyres play a role in global climate by transporting heat from low to high latitudes. The Gulf Stream in the North Atlantic, a strong western boundary current, moves approximately 30 million cubic meters of water per second through the Florida Straits. The heat released from the Norwegian Current, part of the North Atlantic subpolar gyre, helps maintain a moderate climate in Northern Europe.
5 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Why are subtropical gyres important for ocean life and ecosystems?
Subtropical gyres are significant to ocean life and ecosystems because they are large rotating ocean currents that influence the distribution of marine organisms and play a role in ocean health.

These gyres can determine the range of a species and transport marine life over great distances. For example, the Gulf Stream and East Australian Current carry larvae to cold temperate coral reefs, and eels rely on the Gulf Stream to travel from Caribbean spawning sites to Europe.

However, subtropical gyres can also accumulate plastic pollution, which poses a threat to marine life through entanglement and ingestion. Plastics can also concentrate pollutants and deliver them to species that ingest them, disrupting food chains and potentially leading to extinctions.
7 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

subtropical gyre, an area of anticyclonic ocean circulation that sits beneath a region of subtropical high pressure. The movement of ocean water within the Ekman layer of these gyres forces surface water to sink, giving rise to the subtropical convergence near 20°–30° latitude.

The centres of subtropical gyres are shifted to the west. This westward intensification of ocean currents was explained by the American meteorologist and oceanographer Henry M. Stommel (1948) as resulting from the fact that the horizontal Coriolis force increases with latitude. This causes the poleward-flowing western boundary current to be a jetlike current that attains speeds of 2 to 4 metres (about 7 to 13 feet) per second. This current transports the excess heat of the low latitudes to higher latitudes. The flow within the equatorward-flowing interior and eastern boundary of the subtropical gyres is quite different. It is more of a slow drift of cooler water that rarely exceeds 10 centimetres (about 4 inches) per second. Associated with these currents is coastal upwelling that results from offshore Ekman transport.

The strongest of the western boundary currents is the Gulf Stream in the North Atlantic Ocean. It carries about 30 million cubic metres (about 1 billion cubic feet) of ocean water per second through the Straits of Florida and roughly 80 million cubic metres (2.8 billion cubic feet) per second as it flows past Cape Hatteras off the coast of North Carolina, U.S. Responding to the large-scale wind field over the North Atlantic, the Gulf Stream separates from the continental margin at Cape Hatteras. After separation, it forms waves or meanders that eventually generate many eddies of warm and cold water. The warm eddies, composed of thermocline water normally found south of the Gulf Stream, are injected into the waters of the continental slope off the coast of the northeastern United States. They drift to the southeast at rates of approximately five to eight centimetres (two to three inches) per second, and after a year they rejoin the Gulf Stream north of Cape Hatteras. Cold eddies of slope water are injected into the region south of the Gulf Stream and drift to the southwest. After two years they reenter the Gulf Stream just north of the Antilles Islands. The path that they follow defines a clockwise-flowing recirculation gyre seaward of the Gulf Stream.

World map showing major ocean current systems, with arrows indicating the direction and speed of warm and cold currents in the Atlantic, Pacific, Indian, Southern, and Arctic Oceans. Warm currents are marked in red and cold currents in blue, with currents labeled by name and symbols denoting those that reverse direction seasonally. A legend explains current speed categories and color codes.

subtropical gyre

Thank you for signing up!