Antarctic Convergence
Encyclopedia
Subantarctic
The Subantarctic is a region in the southern hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° – 60° south of the Equator. The subantarctic region includes many islands in the southern parts of the Indian Ocean, Atlantic Ocean and...
. Antarctic waters predominantly sink beneath subantarctic waters, while associated zones of mixing and upwelling
Upwelling
Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water. The increased availability in upwelling regions results in high levels of primary...
create a zone very high in marine productivity, especially for Antarctic krill
Antarctic krill
Antarctic krill, Euphausia superba, is a species of krill found in the Antarctic waters of the Southern Ocean. It is a shrimp-like crustacean that lives in large schools, called swarms, sometimes reaching densities of 10,000–30,000 individual animals per cubic metre...
. This line, like the Arctic tree line, is a natural boundary rather than an artificial one, like a line of latitude. It not only separates two hydrological regions
Hydrology
Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...
, but also separates areas of distinctive marine life associations and of different climate
Climate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...
s. There is no Arctic
Arctic
The Arctic is a region located at the northern-most part of the Earth. The Arctic consists of the Arctic Ocean and parts of Canada, Russia, Greenland, the United States, Norway, Sweden, Finland, and Iceland. The Arctic region consists of a vast, ice-covered ocean, surrounded by treeless permafrost...
equivalent, due to the amount of land surrounding the northern polar region.
History
The Antarctic Convergence was first crossed by Anthony de la RochéAnthony de la Roché
Anthony de la Roché, born sometime in the 17th century, was an English merchant born in London to a French Huguenot father and an English mother...
in 1675, and described by Sir Edmund Halley in 1700.
Location
The Antarctic Convergence is actually a zone approximately 32 to 48 km (19.9 to 29.8 mi) wide, varying somewhat in latitude seasonally and in different longitudeLongitude
Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....
s, extending across the Atlantic
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, Pacific
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, and Indian
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
Ocean
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
s between the 48th
48th parallel south
The 48th parallel south is a circle of latitude that is 48 degrees south of the Earth's equatorial plane. It crosses the Atlantic Ocean, the Indian Ocean, the Pacific Ocean and South America....
and 61st
61st parallel south
The 61st parallel south is a circle of latitude that is 61 degrees south of the Earth's equatorial plane. No land lies on the parallel—it crosses nothing but the Southern Ocean....
parallels of south latitude. Although the northern boundary varies, for the purposes of the Convention for the Conservation of Antarctic Marine Living Resources 1980, it is defined as "50°S, 0°; 50°S, 30°E; 45°S, 30°E; 45°S, 80°E; 55°S, 80°E; 55°S, 150°E; 60°S, 150°E; 60°S, 50°W; 50°S, 50°W; 50°S, 0°." Although this zone is a mobile one, it usually does not stray more than half a degree of latitude from its mean position. The precise location at any given place and time is made evident by the sudden drop in temperature from north to south of, on average, 2.8 °C (37 °F) to 5.6 °C (42.1 °F) to below 2 °C (35.6 °F).
The Falkland Islands
Falkland Islands
The Falkland Islands are an archipelago in the South Atlantic Ocean, located about from the coast of mainland South America. The archipelago consists of East Falkland, West Falkland and 776 lesser islands. The capital, Stanley, is on East Falkland...
, Prince Edward Islands
Prince Edward Islands
The Prince Edward Islands are two small islands in the sub-antarctic Indian Ocean that are part of South Africa. The islands, named Marion Island and Prince Edward Island, are located at ....
, Crozet Islands
Crozet Islands
The Crozet Islands are a sub-antarctic archipelago of small islands in the southern Indian Ocean. They form one of the five administrative districts of the French Southern and Antarctic Lands.-Geography:...
, Île Amsterdam
Île Amsterdam
New Amsterdam, Amsterdam Island, or Île Amsterdam is a French island in the Indian Ocean located at . It is part of the French Southern and Antarctic Lands.- History :...
, Île Saint-Paul
Île Saint-Paul
Île Saint-Paul is an island forming part of the French Southern and Antarctic Lands in the Indian Ocean, with an area of . It is located about southwest of the larger Île Amsterdam, and south of Réunion...
, Tierra del Fuego
Tierra del Fuego
Tierra del Fuego is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of a main island Isla Grande de Tierra del Fuego divided between Chile and Argentina with an area of , and a group of smaller islands including Cape...
and Macquarie Island
Macquarie Island
Macquarie Island lies in the southwest corner of the Pacific Ocean, about half-way between New Zealand and Antarctica, at 54°30S, 158°57E. Politically, it has formed part of the Australian state of Tasmania since 1900 and became a Tasmanian State Reserve in 1978. In 1997 it became a world heritage...
lie north of the Antarctic Convergence. The Kerguelen Islands
Kerguelen Islands
The Kerguelen Islands , also known as the Desolation Islands, are a group of islands in the southern Indian Ocean constituting the emerged part of the otherwise submerged Kerguelen Plateau. The islands, along with Adélie Land, the Crozet Islands and the Amsterdam and Saint Paul Islands are part of...
lie approximately on the Convergence. The South Shetland Islands
South Shetland Islands
The South Shetland Islands are a group of Antarctic islands, lying about north of the Antarctic Peninsula, with a total area of . By the Antarctic Treaty of 1959, the Islands' sovereignty is neither recognized nor disputed by the signatories and they are free for use by any signatory for...
, South Orkney Islands
South Orkney Islands
The South Orkney Islands are a group of islands in the Southern Ocean, about north-east of the tip of the Antarctic Peninsula. They have a total area of about ....
, South Georgia and the South Sandwich Islands
South Georgia and the South Sandwich Islands
South Georgia and the South Sandwich Islands is a British overseas territory and overseas territory of the European Union in the southern Atlantic Ocean. It is a remote and inhospitable collection of islands, consisting of South Georgia and a chain of smaller islands, known as the South Sandwich...
, Bouvet Island
Bouvet Island
Bouvet Island is an uninhabited Antarctic volcanic island in the South Atlantic Ocean, 2,525 km south-southwest of South Africa. It is a dependent territory of Norway and, lying north of 60°S latitude, is not subject to the Antarctic Treaty. The centre of the island is an ice-filled crater of an...
, Heard Island and McDonald Islands all lie south of the Convergence.
See also
- AntarcticAntarcticThe Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...
- Antarctic CircleAntarctic CircleThe Antarctic Circle is one of the five major circles of latitude that mark maps of the Earth. For 2011, it is the parallel of latitude that runs south of the Equator.-Description:...
- Antarctic Circumpolar WaveAntarctic Circumpolar WaveThe Antarctic Circumpolar Wave is a coupled ocean/atmosphere wave that circles the Southern Ocean in approximately eight years. Since it is a wave-2 phenomenon at each fixed point in space a signal with a period of four years is seen...
- Antarctic OceanSouthern OceanThe Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions...
- Polar frontPolar frontIn meteorology, the polar front is the boundary between the polar cell and the Ferrel cell in each hemisphere. At this boundary a sharp gradient in temperature occurs between these two air masses, each at very different temperatures....