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Agulhas Return Current
The Agulhas Return Current (ARC) is an ocean current in the South Indian Ocean. The ARC contributes to the water exchange between oceans by forming a link between the South Atlantic Current and the South Indian Ocean Current. It can reach velocities of up to and is therefore popular among participants in trans-oceanic sailing races. Oceanography The ARC originates from the Agulhas Current, the western boundary current of the Indian Ocean, at the Agulhas Retroflection south of Africa and flows east along the Subtropical Front, roughly around 39°S, north of the Antarctic Circumpolar Current. The Agulhas Current follows the continental shelf of the African east-coast, pass through the Agulhas Passage until it leaves the Agulhas Bank and reaches the Agulhas Basin south of South Africa. From there it retroflects almost completely back into the south Indian Ocean as the ARC, and only a smaller part, known as Agulhas leakage, is shed into the South Atlantic. The water mass los ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agulhas Current System
Agulhas (''needles'' in the Portuguese language — or ) may refer to: * Cape Agulhas, the southernmost point of Africa * L'Agulhas, a town near the Cape * Cape Agulhas Lighthouse, located at the Cape * Cape Agulhas Local Municipality, the municipality governing the area around Bredasdorp, including the Cape * Agulhas National Park, a national park protecting areas around Cape Agulhas * The Agulhas Bank, an area of ocean south of the Cape * The Agulhas Current The Agulhas Current () is the western boundary current of the southwest Indian Ocean. It flows south along the east coast of Africa from 27°S to 40°S. It is narrow, swift and strong. It is suggested that it is the largest western boundary curren ..., an ocean current off the east coast of South Africa * South African research ships: : **'' S. A. Agulhas'' **'' S. A. Agulhas II'' {{disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agulhas Basin
The Agulhas Basin is an oceanic basin located south of South Africa where the South Atlantic Ocean and south-western Indian Ocean meet. Part of the African Plate, it is bounded by the Agulhas Ridge (part of the Agulhas-Falkland Fracture Zone) to the north and the Southwest Indian Ridge to the south; by the Meteor Rise to the west and the Agulhas Plateau to the east. Numerous bathymetric anomalies hint at the basin's dynamic tectonic history. Geology In a Late Paleocene (59-56 Ma) reconstruction of the opening of the South Atlantic Ocean (i.e. the separation of South America and Africa during the Gondwana break-up) the Meteor Rise lies conjugate to the Islas Orcadas Rise (east of the Falkland Plateau). The separation of the Meteor Rise and the Islas Orcadas Rise marks the beginning of the formation of the Agulhas Basin. The Agulhas Ridge extends from the northern tip of the Meteor Rise towards the Agulhas Bank south of South Africa. The ridge, however, ends abruptly in a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kerguelen Islands
The Kerguelen Islands ( or ; in French commonly ' but officially ', ), also known as the Desolation Islands (' in French), are a group of islands in the sub-Antarctic constituting one of the two exposed parts of the Kerguelen Plateau, a large igneous province mostly submerged in the southern Indian Ocean. They are among the most isolated places on Earth, located more than from Madagascar. The islands, along with Adélie Land, the Crozet Islands, Amsterdam and Saint Paul islands, and France's Scattered Islands in the Indian Ocean, are part of the French Southern and Antarctic Lands and are administered as a separate district. The main island, Grande Terre, is in area, about three quarters of the size of Corsica, and is surrounded by a further 300 smaller islands and islets, forming an archipelago of . The climate is harsh and chilly with frequent high winds throughout the year. The surrounding seas are generally rough and they remain ice-free year-round. There are no i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crozet Basin
Crozet may refer to: * Crozet Islands, a sub-antarctic archipelago of small islands in the southern Indian Ocean, part of the French Southern Territories * Crozet, a commune in France of the Ain département, in France * Crozet, Virginia, a census-designated place, United States * Benoit Claudius Crozet Claude "Claudius" Crozet (December 31, 1789 – January 29, 1864) was a soldier, educator, and civil engineer. Crozet was born in France and trained as an artillery officer and civil engineer. After the defeat of Napoleon's army, he emigrated t ..., educator and civil engineer (1789-1864) * Crozets de Savoie, a type of pasta {{disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Indian Subtropical Gyre
South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþaz'' ("south"), possibly related to the same Proto-Indo-European root that the word ''sun'' derived from. Some languages describe south in the same way, from the fact that it is the direction of the sun at noon (in the Northern Hemisphere), like Latin meridies 'noon, south' (from medius 'middle' + dies 'day', cf English meridional), while others describe south as the right-hand side of the rising sun, like Biblical Hebrew תֵּימָן teiman 'south' from יָמִין yamin 'right', Aramaic תַּימנַא taymna from יָמִין yamin 'right' and Syriac ܬܰܝܡܢܳܐ taymna from ܝܰܡܝܺܢܳܐ yamina (hence the name of Yemen, the land to the south/right of the Levant). Navigation By convention, the ''bottom or down-facing side'' of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agulhas Plateau
The Agulhas Plateau is an oceanic plateau located in the south-western Indian Ocean about south of South Africa. It is a remainder of a large igneous province (LIP), the Southeast African LIP, that formed (Ma) at or near the triple junction where Gondwana broke-up into Antarctica, South America, and Africa. The plateau formed together with Northeast Georgia Rise and Maud Rise (now located near the Falkland Island and Antarctica respectively) when the region passed over the Bouvet hotspot. Geology History of research The Agulhas Plateau is one of the key structures in the reconstruction of the Gondwana break-up. It was first mapped in 1964 (i.e. part of what would become the Heezen- Tharp map of the world's ocean floor finally published in 1977), but its crustal composition, paleoposition, and geological origin remained enigmatic for decades. The boundary between the Earth's crust and the mantle (the Moho) rises from between the Agulhas Bank (south of South Africa) and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primary Productivity
In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through chemosynthesis, which uses the oxidation or reduction of inorganic chemical compounds as its source of energy. Almost all life on Earth relies directly or indirectly on primary production. The organisms responsible for primary production are known as ''primary producers'' or autotrophs, and form the base of the food chain. In terrestrial ecoregions, these are mainly plants, while in aquatic ecoregions algae predominate in this role. Ecologists distinguish primary production as either ''net'' or ''gross'', the former accounting for losses to processes such as cellular respiration, the latter not. Overview Primary production is the production of chemical energy in organic compounds by living organisms. The main source of this energy is sun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eddy (fluid Dynamics)
In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid is in a turbulent flow regime. The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object. Fluid behind the obstacle flows into the void creating a swirl of fluid on each edge of the obstacle, followed by a short reverse flow of fluid behind the obstacle flowing upstream, toward the back of the obstacle. This phenomenon is naturally observed behind large emergent rocks in swift-flowing rivers. An eddy is a movement of fluid that deviates from the general flow of the fluid. An example for an eddy is a vortex which produces such deviation. However, there are other types of eddies that are not simple vortices. For example, a Rossby wave is an eddy which is an undulation that is a deviation from mean flow, but doesn't have the local closed streamlines of a vortex. Swirl and eddies in engineering The propensity of a fluid to swirl is use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rossby Wave
Rossby waves, also known as planetary waves, are a type of inertial wave naturally occurring in rotating fluids. They were first identified by Sweden-born American meteorologist Carl-Gustaf Arvid Rossby. They are observed in the atmospheres and oceans of planets owing to the rotation of the planet. Atmospheric Rossby waves on Earth are giant meanders in high-altitude winds that have a major influence on weather. These waves are associated with pressure systems and the jet stream (especially around the polar vortices). Oceanic Rossby waves move along the thermocline: the boundary between the warm upper layer and the cold deeper part of the ocean. Rossby wave types Atmospheric waves Atmospheric Rossby waves result from the conservation of potential vorticity and are influenced by the Coriolis force and pressure gradient. The rotation causes fluids to turn to the right as they move in the northern hemisphere and to the left in the southern hemisphere. For example, a fluid th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Atlantic
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe and Asia from the "New World" of the Americas in the European perception of the World. The Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Europe and Africa to the east, and North and South America to the west. As one component of the interconnected World Ocean, it is connected in the north to the Arctic Ocean, to the Pacific Ocean in the southwest, the Indian Ocean in the southeast, and the Southern Ocean in the south (other definitions describe the Atlantic as extending southward to Antarctica). The Atlantic Ocean is divided in two parts, by the Equatorial Counter Current, with the North(ern) Atlantic Ocean and the South(ern) Atlantic Ocean split at about 8°N. Scientific explorations of the Atlanti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retroflect
Retroflection is the movement of an ocean current that doubles back on itself. Usage history More commonly used to describe the way the mammalian intestine or uterus might turn back on itself, retroflection was first used in an oceanographic sense in 1970 by South African oceanographer Nils Bang, to describe the Agulhas Current which curves on itself at the southern tip of Africa to become the Aghulhas Return Current. Bang credited the inspiration for the metaphor to his wife, Alison Coombe Bang, a nursing sister, who mentioned the term during her midwifery studies. Bang's research, through the University of Cape Town, was done on a limited budget and with rudimentary equipment,Sciendaba, Vol XII No 48, 15 December 1977 yet his studies using closely spaced bathythermograph readings, were later corroborated by satellite thermal imagery. The term was then revived and is now common parlance among oceanographers. The Agulhas current's retroflection is now key to an understanding of its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agulhas Bank
The Agulhas Bank (, from Portuguese for Cape Agulhas, ''Cabo das Agulhas'', "Cape of Needles") is a broad, shallow part of the southern African continental shelf which extends up to south of Cape Agulhas before falling steeply to the abyssal plain. It is the ocean region where the warm Indian Ocean and the cold Atlantic Ocean meet. This convergence leads to treacherous sailing conditions, accounting for numerous wrecked ships in the area over the years. However, the meeting of the oceans here also fuels the nutrient cycle for marine life, making it one of the best fishing grounds in South Africa. Extent and characteristics South African marine ecoregions from the 2011 classification The Agulhas Bank stretches approximately along the African coast, from off Cape Peninsula (18°E) to Port Alfred (26°E), and up to from it. The bank slopes down relatively steeply from the coast to about deep and reaches before dropping steeply to on its southern edge. The shelf s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
