Difference between revisions of "Indian Ocean" - New World Encyclopedia

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The ''''''Indian Ocean'''''' is the third-largest''' body of water''' in the world, covering about 20% of the Earth's water surface. It is ''bounded'' on the north by southern [[Asia]] (the [[Indian subcontinent]]); on the west by the [[Arabia|Arabian Peninsula]] and [[Africa]]; on the east by the [[Malay Peninsula]], the [[Sunda Islands]], and [[Australia]]; and on the south by the [[Southern Ocean]]. It is separated from the [[Atlantic Ocean]] by the 20°east [[Meridian (geography)|meridian]] south of Africa, and from the [[Pacific Ocean|Pacific]] by the 147°east meridian. The northernmost extent of the Indian Ocean is approximately 30°north [[latitude]] in the [[Persian Gulf]]. This ocean is nearly 10,000 km (6,200 mi) wide at the southern tips of Africa and Australia; its area is 73,556,000 km² (28,400,000 mi²), including the [[Red Sea]] and the Persian Gulf. The ocean's volume is estimated to be [[1 E15 m³|292,131,000 km³]] (70,086,000 mi³). Small islands dot the continental rims. [[Island]] nations within the ocean are [[Madagascar]] (formerly Malagasy Republic), the world's fourth largest island; [[Comoros]]; [[Seychelles]]; [[Maldives]]; [[Mauritius]]; and [[Sri Lanka]]. [[Indonesia]] borders it. The ocean's importance as a transit route between Asia and Africa has made it a scene of conflict. Because of its size, however, no one nation had successfully dominated until the early 1800s when [[United Kingdom|Britain]] controlled much of the surrounding land.
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{{Unreferenced|date=June 2007}}
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{{Five oceans}}
 
[[Image:Indianocean.PNG|right]]
 
[[Image:Indianocean.PNG|right]]
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:''This article is about the water body. For the Indian fusion music band, see [[Indian Ocean (band)]].''
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The '''Indian Ocean''' is the third largest of the world's [[ocean]]ic divisions, covering about 20% of the [[Earth]]'s water surface. It is bounded on the north by [[Asia]] (including the [[Indian subcontinent]], after which it is named); on the west by [[Africa]]; on the east by the [[Malay Peninsula]], the [[Sunda Islands]], and [[Australia]]; and on the south by the [[Southern Ocean]] (or, traditionally, by [[Antarctica]]).  One component of the all-encompassing [[World Ocean]], the Indian Ocean is delineated from the [[Atlantic Ocean]] by the 20° east [[Meridian (geography)|meridian]] running south from [[Cape Agulhas]],<ref>[http://ioc.unesco.org/oceanteacher/OceanTeacher2/01_GlobOcToday/03_GeopolOc/s23_1953.pdf ''Limits of Oceans and Seas'']. International Hydrographic Organization Special Publication No. 23, 1953.</ref> and from the [[Pacific Ocean|Pacific]] by the 147° east meridian. The northernmost extent of the Indian Ocean is approximately 30° north [[latitude]] in the [[Persian Gulf]] and, thus, has asymmetric ocean circulation.  This ocean is nearly 10,000&nbsp;kilometers (6,200&nbsp;mi) wide at the southern tips of Africa and Australia; its area is [[1 E+13 m²|73,556,000&nbsp;square&nbsp;kilometers]] (28,400,000&nbsp;mi²), including the [[Red Sea]] and the Persian Gulf.
  
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==Environment==
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The ocean's volume is estimated to be [[1 E+17 m³|292,131,000&nbsp;cubic&nbsp;kilometers]] (70,086,000&nbsp;mi³). Small islands dot the continental rims. [[Island]] nations within the ocean are [[Madagascar]] (formerly Malagasy Republic), the world's fourth largest island; [[Comoros]]; [[Seychelles]]; [[Maldives]]; [[Mauritius]]; and [[Sri Lanka]]. [[Indonesia]] borders it. The ocean's importance as a transit route between [[Asia]] and Africa has made it a scene of conflict. Because of its size, however, no nation had successfully dominated most of it until the early 1800s when [[United Kingdom|Britain]] controlled much of the surrounding land. Since [[World War II]], the ocean has been dominated by [[India]] and [[Australia]].
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The African, Indian, and Antarctic crustal plates converge in the Indian Ocean. Their junctures are marked by branches of the Mid-Oceanic Ridge forming an inverted Y, with the stem running south from the edge of the continental shelf near [[Mumbai]], [[India]]. The eastern, western, and southern basins thus formed are subdivided into smaller basins by ridges. The ocean's continental shelves are narrow, averaging 200 km (125 mi) in width. An exception is found off Australia's western coast, where the shelf width exceeds 1,000 km (600 mi). The average depth of the ocean is 3,890 m (12,760 ft). Its deepest point, in the [[Java Trench]], is estimated to be 7,450 m (24,442 ft). North of 50° south latitude, 86% of the main basin is covered by [[pelagic]] sediments, of which more than one-half is [[globigerina ooze]]. The remaining 14% is layered with [[terrigenous]] sediments. Glacial outwash dominates the extreme southern latitudes.
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==Geography==
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The African, Indian, and Antarctic crustal plates converge in the Indian Ocean. Their junctures are marked by branches of the Mid-Oceanic Ridge forming an inverted Y, with the stem running south from the edge of the continental shelf near [[Mumbai]], [[India]]. The eastern, western, and southern basins thus formed are subdivided into smaller basins by ridges. The ocean's continental shelves are narrow, averaging 200&nbsp;kilometers (125 mi) in width. An exception is found off Australia's western coast, where the shelf width exceeds 1,000&nbsp;kilometers (600 mi). The average depth of the ocean is 3,890&nbsp;meters (12,760 ft). Its deepest point, is  in the [[Diamantina Deep]] close to the coast of south west [[Western Australia]]. North of 50° south latitude, 86% of the main basin is covered by [[pelagic]] sediments, of which more than half is [[Globigerinida|globigerina ooze]]. The remaining 14% is layered with [[terrigenous]] sediments. Glacial outwash dominates the extreme southern latitudes.
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A spring 2000 decision by the [[International Hydrographic Organization]] delimited a [[Southern Ocean|fifth world ocean]], stripping the southern portions of the Indian Ocean. The new ocean extends from the coast of Antarctica north to 60° south latitude which coincides with the Antarctic Treaty Limit. The Indian Ocean remains the third-largest of the world's five oceans.
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Major chokepoints include [[Bab el Mandeb]], [[Strait of Hormuz]], [[Strait of Malacca]], southern access to the [[Suez Canal]], and the [[Lombok Strait]]. Seas include [[Andaman Sea]], [[Arabian Sea]], [[Bay of Bengal]], [[Great Australian Bight]], [[Gulf of Aden]], [[Gulf of Oman]], [[Laccadive Sea]], [[Mozambique Channel]], [[Persian Gulf]], [[Red Sea]], Strait of Malacca, and other tributary water bodies.
  
 
===Climate===
 
===Climate===
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The climate north of the [[equator]] is affected by a [[Monsoon]] wind system. Strong northeast winds blow from October until April; from May until October south and west winds prevail. In the [[Arabian Sea]] the violent monsoon brings rain to the Indian subcontinent. In the southern hemisphere the winds generally are milder, but summer storms near Mauritius can be severe. When the monsoon winds change, cyclones sometimes strike the shores of the Arabian Sea and the [[Bay of Bengal]].
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The climate north of the [[equator]] is affected by a [[monsoon]] or [[tornado]] wind system. Strong northeast winds blow from October until April; from May until October south and west winds prevail. In the [[Arabian Sea]] the violent monsoon brings rain to the Indian subcontinent. In the southern hemisphere the winds generally are milder, but summer storms near Mauritius can be severe. When the monsoon winds change, cyclones sometimes strike the shores of the Arabian Sea and the [[Bay of Bengal]]. The Indian Ocean happens to be the warmest ocean in the world.
  
 
===Hydrology===
 
===Hydrology===
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[[Image:Indian_Ocean_bathymetry_srtm.png|thumb|right|Bathymetric map of the Indian Ocean]]
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[[Image:Indian Ocean bathymetry srtm.png|thumb|right|Bathymetric map of the Indian Ocean]]
  
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Among the few large rivers flowing into the Indian Ocean are the [[Zambezi]], [[Shatt al-Arab|Arvandrud/Shatt-al-Arab]], [[Indus River|Indus]], [[Ganges River|Ganges]], [[Brahmaputra]], and [[Irrawaddy]]. Currents are largely controlled by the monsoon. Two large circular currents, one in the northern hemisphere flowing clockwise and one south of the equator moving counterclockwise, constitute the dominant flow pattern. During the winter monsoon, however, currents in the north are reversed. Deepwater circulation is controlled primarily by inflows from the Atlantic Ocean, the Red Sea, and Antarctic currents. North of 20°south latitude the minimum surface temperature is 22°C (72°F), exceeding 28°C (82°F) to the east. Southward of 40°south latitude, temperatures drop quickly. Surface water salinity ranges from 32 to 37 parts per 1,000, the highest occurring in the Arabian Sea and in a belt between southern Africa and southwestern Australia. Pack ice and icebergs are found throughout the year south of about 65°south latitude. The average northern limit of icebergs is 45°south latitude.
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Among the few large rivers flowing into the Indian Ocean are the [[Zambezi]], [[Shatt al-Arab|Arvandrud/Shatt-al-Arab]], [[Indus River|Indus]], [[Ganges River|Ganges]], [[Brahmaputra]], and [[Ayeyarwady River]]. Currents are mainly controlled by the monsoon. Two large circular currents, one in the northern hemisphere flowing clockwise and one south of the equator moving counterclockwise, constitute the dominant flow pattern. During the winter monsoon, however, currents in the north are reversed. Deepwater circulation is controlled primarily by inflows from the [[Atlantic Ocean]], the [[Red Sea]], and Antarctic currents. North of 20° south latitude the minimum surface temperature is 22&nbsp;°C (72&nbsp;°F), exceeding 28&nbsp;°C (82 °F) to the east. Southward of 40° south latitude, temperatures drop quickly. Surface water [[salinity]] ranges from 32 to 37 parts per 1000, the highest occurring in the Arabian Sea and in a belt between southern Africa and southwestern Australia. Pack ice and icebergs are found throughout the year south of about 65° south latitude. The average northern limit of icebergs is 45° south latitude.
  
 
==Economy==
 
==Economy==
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The Indian Ocean provides major sea routes connecting the [[Middle East]], [[Africa]], and [[East Asia]] with [[Europe]] and the Americas. It carries a particularly heavy traffic of petroleum and petroleum products from the oilfields of the Persian Gulf and Indonesia. Large reserves of hydrocarbons are being tapped in the offshore areas of [[Saudi Arabia]], [[Iran]], [[India]], and western [[Australia]]. An estimated 40% of the world's offshore oil production comes from the Indian Ocean. Beach sands rich in heavy [[mineral]]s and offshore placer deposits are actively exploited by bordering countries, particularly [[India]], [[South Africa]], [[Indonesia]], [[Sri Lanka]], and [[Thailand]].
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The Indian Ocean provides major sea routes connecting the [[Middle East]], Africa, and [[East Asia]] with [[Europe]] and the [[Americas]]. It carries a particularly heavy traffic of [[petroleum]] and petroleum products from the oilfields of the Persian Gulf and Indonesia. Large reserves of hydrocarbons are being tapped in the offshore areas of [[Saudi Arabia]], [[Iran]], [[India]], and Western Australia. An estimated 40% of the world's offshore oil production comes from the Indian Ocean. Beach sands rich in heavy [[mineral]]s, and offshore placer deposits are actively exploited by bordering countries, particularly India, [[South Africa]], Indonesia, [[Sri Lanka]], and [[Thailand]].
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The warmth of the ''Indian Ocean'' keeps [[plankton|phytoplankton]] production low, except along the northern fringes and in a few scattered spots elsewhere; life in the ocean is thus limited. [[Fishing]] is confined to subsistence levels. Its fish are of great and growing importance to the bordering countries for domestic consumption and export. Fishing fleets from [[Russia]], [[Japan]], [[South Korea]], and [[Taiwan]] also exploit the Indian Ocean, mainly for [[shrimp]] and [[tuna]].
  
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The warmth of the Indian Ocean keeps [[plankton|phytoplankton]] production low, except along the northern fringes and in a few scattered spots elsewhere; life in the ocean is thus limited. [[Fishing]] is confined to subsistence levels. Its fish are of great and growing importance to the bordering countries for domestic consumption and export. Fishing fleets from [[Russia]], [[Japan]], [[South Korea]], and [[Taiwan]] also exploit the Indian Ocean, mainly for shrimp and tuna.
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Endangered marine species include the [[dugong]], [[seal (mammal)|seal]]s, [[turtle]]s, and [[whale]]s.
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Oil [[pollution]] threatens the [[Arabian Sea]], [[Persian Gulf]], and [[Red Sea]]
  
 
==History==
 
==History==
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The earliest known civilizations, in the valleys of the [[Nile]], [[Euphrates]], [[Tigris]], and Indus rivers and in Southeast Asia, have developed near the Indian Ocean. During [[Egypt]]'s 1st dynasty (c. 3000 BCE), sailors were sent out onto its waters, journeying to [[Punt (region)|Punt]], thought to be part of present-day [[Somalia]]. Returning ships brought gold and Myrrh. [[Phoenicia]]ns of the [[3rd millennium BCE]] may have entered the area, but no settlements resulted.
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The world's earliest civilizations in [[Mesopotamia]] (beginning with [[Sumer]]), [[ancient Egypt]], and the [[Indian subcontinent]] (beginning with the [[Indus Valley Civilization|Indus Valley civilization]]), which began along the valleys of the [[Tigris]]-[[Euphrates]], [[Nile]] and [[Indus River|Indus]] rivers respectively, had all developed around the Indian Ocean. Civilizations soon arose in [[Iran|Persia]] (beginning with [[Elam]]) and later in [[Southeast Asia]] (beginning with [[Funan]]). During [[Egypt]]'s first dynasty (c. 3000 B.C.E.), sailors were sent out onto its waters, journeying to [[Punt (region)|Punt]], thought to be part of present-day [[Somalia]]. Returning ships brought gold and myrrh. The earliest known maritime trade between Mesopotamia and the Indus Valley (c. 2500 B.C.E.) was conducted along the Indian Ocean. [[Phoenicia]]ns of the late [[3rd millennium B.C.E.]] may have entered the area, but no settlements resulted.
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The Indian Ocean is far calmer and thus open to trade earlier than the [[Atlantic]] or [[Pacific]]. The powerful [[monsoon]]s also meant ships could easily sail them west early in the season, then wait a few months and return eastwards. This allowed [[Indonesian]] peoples to cross the Indian Ocean to settle in [[Madagascar]].
 
  
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In the second or first century B.C.E. [[Eudoxus of Cyzicus]] was the first [[Greece|Greek]] to cross the Indian Ocean. [[Hippalus]] is said to have discovered the direct route from [[Arabia]] to [[India]] around this time. During the first and second century CE intensive [[Roman commerce|trade relations]] developed between [[Roman Egypt]] and the [[Tamil people|Tamil kingdoms]] of the [[Cheras]], [[Cholas]] and [[Pandyas]] in Southern India. Like the Indonesian people above, the western sailors used the monsoon to cross the Ocean. The unknown author of the ''[[Periplus of the Erythraean Sea]]'' describes this route and the ports and trade goods along the coasts of [[Africa]] and [[India]] around 70 C.E..
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The Indian Ocean is far calmer and thus opened to trade earlier than the Atlantic or [[Pacific]] Oceans. The powerful monsoons also meant ships could easily sail west early in the season, then wait a few months and return eastwards. This allowed [[Indonesia]]n peoples to cross the Indian Ocean to settle in Madagascar.
  
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In 1497 [[Vasco da Gama]] rounded the [[Cape of Good Hope]] and sailed to India, the first European to do so. The European ships, armed with heavy cannon, quickly came to dominate the trade. [[Portugal]] at first attempted to achieve pre-eminence setting up forts an the important straits and ports. But the small nation was unable to support such a vast project and they were replaced in the mid-1600s by other European powers. The [[Dutch East India Company]] (1602-1798) sought control of trade with the East across the Indian Ocean. [[France]] and Britain established trade companies for the area. Eventually Britain became the principal power and by 1815 dominated the area.
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In the second or first century B.C.E., [[Eudoxus of Cyzicus]] was the first [[Greece|Greek]] to cross the Indian Ocean. [[Hippalus]] is said to have discovered the direct route from [[Arabia]] to India around this time. During the first and second centuries intensive [[Roman commerce|trade relations]] developed between [[Roman Egypt]] and the [[Tamil people|Tamil kingdoms]] of the [[Cheras]], [[Cholas]] and [[Pandyas]] in [[South India|Southern India]]. Like the Indonesian peoples above, the western sailors used the monsoon to cross the ocean. The unknown author of the ''[[Periplus of the Erythraean Sea]]'' describes this route and the ports and trade goods along the coasts of Africa and India around 70 C.E.
  
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The opening of the [[Suez Canal]] in 1869 revived European interest in the East, but no nation was successful in establishing trade dominance. Since [[World War II]] the United Kingdom has withdrawn from the area, to be only partially replaced by India, the Soviet Union, and the [[United States]]. The last two have tried to establish hegemony by negotiating for naval base sites. Developing countries bordering the ocean, however, seek to have it made a "zone of peace" so that they may use its shipping lanes freely. Though the United States did manage to salvage a naval base for itself at Deigo Garcia in the middle of the Indian Ocean.
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From 1405 to 1433, Admiral [[Zheng He]] led large fleets of the [[Ming Dynasty]] on several voyages to the Western Ocean ([[Chinese language|Chinese]] name for the Indian Ocean) and reached the coastal country of [[East Africa]].{{Fact|date=February 2007}}
  
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On December 26 2004 the countries surrounding the Indian Ocean were hit by [[tsunami]]s caused by the [[2004 Indian Ocean earthquake]]. The waves resulted in more than 226,000 deaths and over 1 million homeless.
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In 1497, [[Vasco da Gama]] rounded the [[Cape of Good Hope]], and became the first European to sail to India. The European ships, armed with heavy cannon, quickly dominated trade. [[Portugal]] at first attempted to achieve pre-eminence by setting up forts at the important straits and ports. But the small nation was unable to support such a vast project, and they were replaced in the mid-17th century by other European powers. The [[Dutch East India Company]] (1602-1798) sought control of trade with the East across the Indian Ocean. [[France]] and Britain established trade companies for the area. Eventually Britain became the principal power and by 1815 dominated the area.
  
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==Data==
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The opening of the [[Suez Canal]] in 1869 revived European interest in the East, but no nation was successful in establishing trade dominance. Since World War II the United Kingdom has withdrawn from the area, to be only partially replaced by India, the [[Soviet Union|USSR]], and the [[United States]]. The last two have tried to establish hegemony by negotiating for naval base sites. Developing countries bordering the ocean, however, seek to have it made a "zone of peace" so that they may use its shipping lanes freely, though the United Kingdom and United States maintain a military base on [[Diego Garcia]] atoll in the middle of the Indian Ocean.
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'''Southern Ocean:'''
 
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A spring 2000 decision by the [[International Hydrographic Organization]] delimited a [[Southern Ocean|fifth world ocean]], stripping the southern portions of the Indian Ocean. The new ocean extends from the coast of Antarctica north to 60°south latitude which coincides with the Antarctic Treaty Limit. The Indian Ocean remains the third-largest of the world's five oceans.
 
  
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'''Area:'''
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On December 26, 2004, the countries surrounding the Indian Ocean were hit by a [[tsunami]] caused by the [[2004 Indian Ocean earthquake]]. The waves resulted in more than 226,000 deaths and over 1 million were left homeless.
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* ''total:'' 68.556 million km&sup2;
 
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* ''seas:'' includes [[Andaman Sea]], [[Arabian Sea]], [[Bay of Bengal]], [[Great Australian Bight]], [[Gulf of Aden]], [[Gulf of Oman]], [[Laccadive Sea]], [[Mozambique Channel]], [[Persian Gulf]], [[Red Sea]], [[Strait of Malacca]], and other tributary water bodies
 
  
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'''Coastline:'''
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==Culture and Literature==
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66,526 km
 
  
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'''Climate:'''
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:''See [[Culture of the Indian Ocean Islands]] and [[Indian Ocean literature]]''
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northeast [[monsoon]] (December to April), southwest monsoon (June to October); tropical cyclones occur during May/June and October/November in the northern Indian Ocean and January/February in the southern Indian Ocean
 
  
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'''Terrain:'''
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==Major ports and harbours==
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surface dominated by counterclockwise gyre (broad, circular system of currents) in the southern Indian Ocean; unique reversal of surface currents in the northern Indian Ocean; low atmospheric pressure over southwest Asia from hot, rising, summer air results in the southwest monsoon and southwest-to-northeast winds and currents, while high pressure over northern Asia from cold, falling, winter air results in the northeast monsoon and northeast-to-southwest winds and currents; ocean floor is dominated by the [[Mid-Indian Ocean Ridge]] and subdivided by the [[Southeast Indian Ocean Ridge]], [[Southwest Indian Ocean Ridge]], and [[Ninetyeast Ridge]]
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{{main|List of ports and harbours of the Indian Ocean}}
  
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Graphics of the seabed terrain produced by the Royal Navy & British Geological Survey in 2005 can be found [[here]].
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==See also==
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{{wiktionary}}
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{{commons}}
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*[[Indian Ocean states]]
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*[[List of islands in the Indian Ocean]]
  
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'''Elevation extremes:'''
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==References==
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* ''lowest point:'' [[Java Trench]] -7,258 m
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<div class="references-small">
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* ''highest point:'' sea level 0 m
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<!--See http://en.wikipedia.org/wiki/Wikipedia:Footnotes for an explanation of how to generate footnotes using the <ref(erences/)> tags—>
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<references/>
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</div>
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*Braun, D., The Indian Ocean (1983)
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*Chandra, S., ed., The Indian Ocean (1987);
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*Chaudhuri, K. N., Trade and Civilization in the Indian Ocean (1985);
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*Cousteau, Jacques-Yves, and [[Philippe Diole|Diole, Philippe]], Life and Death in a Coral Sea (1971);
 +
*Cubitt, Gerald, Islands of the Indian Ocean (1975);
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*Das Gupta, A., and Pearson, M.N., India and the Indian Ocean (1987);
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*Dowdy, W. L., and Trood, R., eds., The Indian Ocean (1985);
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*Kerr, A., ed., Resources and Development in the Indian Ocean Region (1981);
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*Nairn, A. E., and Stehli, F. G., eds., The Ocean Basins and Margins, Vol. 6: The Indian Ocean (1982);
 +
*Ostheimer, John M., ed., The Politics of the Western Indian Ocean Islands (1975);
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*Torabully, Khal, Coolitude: An Anthology of the Indian Labour Diaspora (with Marina Carter, Anthem Press, London, 2002) ISBN 1843310031
 +
*Toussaint, Auguste, The History of the Indian Ocean, trans. by June Guicharnaud (1966).
  
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'''Natural resources:'''
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''Much of this text is based on public domain text by US Naval Oceanographer at: http://oceanographer.navy.mil/indian.html''
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[[petroleum|oil]] and gas fields, [[fish]], [[shrimp]], sand and gravel aggregates, placer deposits, polymetallic nodules
 
  
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'''Environment - current issues:'''
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==External links==
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endangered marine species include the [[dugong]], [[seal (mammal)|seal]]s, [[turtle]]s, and [[whale]]s; oil [[pollution]] in the Arabian Sea, [[Persian Gulf]], and [[Red Sea]]
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* [http://www.whoi.edu/imageOfDay.do Oceanography Image of the Day ], from the Woods Hole Oceanographic Institution
 +
* [http://dapper.pmel.noaa.gov/dchart/index.html?map=-11.25,73.125&z=2 NOAA In-situ Ocean Data Viewer] Plot and download ocean observations
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* [http://www.rttp-io.org/en/ The Regional Tuna Tagging Project-Indian Ocean with details of the importance of Tuna in the Indian Ocean]  
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* [http://www.alphavilla.co.uk/mauritius_map_indian_ocean.html Detailed maps of the Indian Ocean]  
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* [http://www.bu.edu/africa/outreach/materials/handouts/indian.html The Indian Ocean Trade: A Classroom Simulation]
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{{SouthAsiaWaters}}
  
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'''Geography - note:'''
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[[Category:Indian Ocean| ]]
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major chokepoints include [[Bab el Mandeb]], [[Strait of Hormuz]], [[Strait of Malacca]], southern access to the [[Suez Canal]], and the [[Lombok Strait]]
 
  
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'''Ports and harbors:'''
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[[be-x-old:Індыйскі акіян]]
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[[Calcutta]] ([[India]]), [[Chennai]] ([[India]]), [[Colombo]] ([[Sri Lanka]]), [[Durban]] ([[South Africa]]), [[Jakarta]] ([[Indonesia]]), [[Karachi]] ([[Pakistan]]), [[Fremantle  ([[Australia]]), [[Mumbai]] [[India]]), [[Richards Bay]] ([[South Africa]]), [[Visakhapatnam]] ([[India]]),[[Kochi]]([[India]])
 
  
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{{credit|29845492}}
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[[frp:Ocèan Endien]]
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[[az:Hind okeanı]]
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[[be:Індыйскі акіян]]
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[[br:Meurvor Indez]]
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[[cv:Инди океанĕ]]
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[[gd:Cuan Innseanach]]
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[[ig:Indian Ocean]]
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[[kn:ಹಿಂದೂ ಮಹಾಸಾಗರ]]
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[[sw:Bahari ya Hindi]]
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[[om:Indian Ocean]]
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[[sa:सिन्धु महासागर]]
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[[so:Badweynta Hindiya]]
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[[tg:Уқёнуси Ҳинд]]
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[[ur:بحر ہند]]
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[[wa:Oceyan Indyin]]
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[[wo:Géejpeek u Indian]]
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[[bat-smg:Indėjės vuondenīns]]
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{{credit|140234618}}

Revision as of 12:40, 26 June 2007


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View of the Earth where all five oceans visible
Earth's oceans
Indianocean.PNG
This article is about the water body. For the Indian fusion music band, see Indian Ocean (band).

The Indian Ocean is the third largest of the world's oceanic divisions, covering about 20% of the Earth's water surface. It is bounded on the north by Asia (including the Indian subcontinent, after which it is named); on the west by Africa; on the east by the Malay Peninsula, the Sunda Islands, and Australia; and on the south by the Southern Ocean (or, traditionally, by Antarctica). One component of the all-encompassing World Ocean, the Indian Ocean is delineated from the Atlantic Ocean by the 20° east meridian running south from Cape Agulhas,[1] and from the Pacific by the 147° east meridian. The northernmost extent of the Indian Ocean is approximately 30° north latitude in the Persian Gulf and, thus, has asymmetric ocean circulation. This ocean is nearly 10,000 kilometers (6,200 mi) wide at the southern tips of Africa and Australia; its area is 73,556,000 square kilometers (28,400,000 mi²), including the Red Sea and the Persian Gulf.

The ocean's volume is estimated to be 292,131,000 cubic kilometers (70,086,000 mi³). Small islands dot the continental rims. Island nations within the ocean are Madagascar (formerly Malagasy Republic), the world's fourth largest island; Comoros; Seychelles; Maldives; Mauritius; and Sri Lanka. Indonesia borders it. The ocean's importance as a transit route between Asia and Africa has made it a scene of conflict. Because of its size, however, no nation had successfully dominated most of it until the early 1800s when Britain controlled much of the surrounding land. Since World War II, the ocean has been dominated by India and Australia.

Geography

The African, Indian, and Antarctic crustal plates converge in the Indian Ocean. Their junctures are marked by branches of the Mid-Oceanic Ridge forming an inverted Y, with the stem running south from the edge of the continental shelf near Mumbai, India. The eastern, western, and southern basins thus formed are subdivided into smaller basins by ridges. The ocean's continental shelves are narrow, averaging 200 kilometers (125 mi) in width. An exception is found off Australia's western coast, where the shelf width exceeds 1,000 kilometers (600 mi). The average depth of the ocean is 3,890 meters (12,760 ft). Its deepest point, is in the Diamantina Deep close to the coast of south west Western Australia. North of 50° south latitude, 86% of the main basin is covered by pelagic sediments, of which more than half is globigerina ooze. The remaining 14% is layered with terrigenous sediments. Glacial outwash dominates the extreme southern latitudes.

A spring 2000 decision by the International Hydrographic Organization delimited a fifth world ocean, stripping the southern portions of the Indian Ocean. The new ocean extends from the coast of Antarctica north to 60° south latitude which coincides with the Antarctic Treaty Limit. The Indian Ocean remains the third-largest of the world's five oceans.

Major chokepoints include Bab el Mandeb, Strait of Hormuz, Strait of Malacca, southern access to the Suez Canal, and the Lombok Strait. Seas include Andaman Sea, Arabian Sea, Bay of Bengal, Great Australian Bight, Gulf of Aden, Gulf of Oman, Laccadive Sea, Mozambique Channel, Persian Gulf, Red Sea, Strait of Malacca, and other tributary water bodies.

Climate

The climate north of the equator is affected by a monsoon or tornado wind system. Strong northeast winds blow from October until April; from May until October south and west winds prevail. In the Arabian Sea the violent monsoon brings rain to the Indian subcontinent. In the southern hemisphere the winds generally are milder, but summer storms near Mauritius can be severe. When the monsoon winds change, cyclones sometimes strike the shores of the Arabian Sea and the Bay of Bengal. The Indian Ocean happens to be the warmest ocean in the world.

Hydrology

Bathymetric map of the Indian Ocean

Among the few large rivers flowing into the Indian Ocean are the Zambezi, Arvandrud/Shatt-al-Arab, Indus, Ganges, Brahmaputra, and Ayeyarwady River. Currents are mainly controlled by the monsoon. Two large circular currents, one in the northern hemisphere flowing clockwise and one south of the equator moving counterclockwise, constitute the dominant flow pattern. During the winter monsoon, however, currents in the north are reversed. Deepwater circulation is controlled primarily by inflows from the Atlantic Ocean, the Red Sea, and Antarctic currents. North of 20° south latitude the minimum surface temperature is 22 °C (72 °F), exceeding 28 °C (82 °F) to the east. Southward of 40° south latitude, temperatures drop quickly. Surface water salinity ranges from 32 to 37 parts per 1000, the highest occurring in the Arabian Sea and in a belt between southern Africa and southwestern Australia. Pack ice and icebergs are found throughout the year south of about 65° south latitude. The average northern limit of icebergs is 45° south latitude.

Economy

The Indian Ocean provides major sea routes connecting the Middle East, Africa, and East Asia with Europe and the Americas. It carries a particularly heavy traffic of petroleum and petroleum products from the oilfields of the Persian Gulf and Indonesia. Large reserves of hydrocarbons are being tapped in the offshore areas of Saudi Arabia, Iran, India, and Western Australia. An estimated 40% of the world's offshore oil production comes from the Indian Ocean. Beach sands rich in heavy minerals, and offshore placer deposits are actively exploited by bordering countries, particularly India, South Africa, Indonesia, Sri Lanka, and Thailand.

The warmth of the Indian Ocean keeps phytoplankton production low, except along the northern fringes and in a few scattered spots elsewhere; life in the ocean is thus limited. Fishing is confined to subsistence levels. Its fish are of great and growing importance to the bordering countries for domestic consumption and export. Fishing fleets from Russia, Japan, South Korea, and Taiwan also exploit the Indian Ocean, mainly for shrimp and tuna.

Endangered marine species include the dugong, seals, turtles, and whales.

Oil pollution threatens the Arabian Sea, Persian Gulf, and Red Sea

History

The world's earliest civilizations in Mesopotamia (beginning with Sumer), ancient Egypt, and the Indian subcontinent (beginning with the Indus Valley civilization), which began along the valleys of the Tigris-Euphrates, Nile and Indus rivers respectively, had all developed around the Indian Ocean. Civilizations soon arose in Persia (beginning with Elam) and later in Southeast Asia (beginning with Funan). During Egypt's first dynasty (c. 3000 B.C.E.), sailors were sent out onto its waters, journeying to Punt, thought to be part of present-day Somalia. Returning ships brought gold and myrrh. The earliest known maritime trade between Mesopotamia and the Indus Valley (c. 2500 B.C.E.) was conducted along the Indian Ocean. Phoenicians of the late 3rd millennium B.C.E. may have entered the area, but no settlements resulted.

The Indian Ocean is far calmer and thus opened to trade earlier than the Atlantic or Pacific Oceans. The powerful monsoons also meant ships could easily sail west early in the season, then wait a few months and return eastwards. This allowed Indonesian peoples to cross the Indian Ocean to settle in Madagascar.

In the second or first century B.C.E., Eudoxus of Cyzicus was the first Greek to cross the Indian Ocean. Hippalus is said to have discovered the direct route from Arabia to India around this time. During the first and second centuries intensive trade relations developed between Roman Egypt and the Tamil kingdoms of the Cheras, Cholas and Pandyas in Southern India. Like the Indonesian peoples above, the western sailors used the monsoon to cross the ocean. The unknown author of the Periplus of the Erythraean Sea describes this route and the ports and trade goods along the coasts of Africa and India around 70 C.E.

From 1405 to 1433, Admiral Zheng He led large fleets of the Ming Dynasty on several voyages to the Western Ocean (Chinese name for the Indian Ocean) and reached the coastal country of East Africa.[citation needed]

In 1497, Vasco da Gama rounded the Cape of Good Hope, and became the first European to sail to India. The European ships, armed with heavy cannon, quickly dominated trade. Portugal at first attempted to achieve pre-eminence by setting up forts at the important straits and ports. But the small nation was unable to support such a vast project, and they were replaced in the mid-17th century by other European powers. The Dutch East India Company (1602-1798) sought control of trade with the East across the Indian Ocean. France and Britain established trade companies for the area. Eventually Britain became the principal power and by 1815 dominated the area.

The opening of the Suez Canal in 1869 revived European interest in the East, but no nation was successful in establishing trade dominance. Since World War II the United Kingdom has withdrawn from the area, to be only partially replaced by India, the USSR, and the United States. The last two have tried to establish hegemony by negotiating for naval base sites. Developing countries bordering the ocean, however, seek to have it made a "zone of peace" so that they may use its shipping lanes freely, though the United Kingdom and United States maintain a military base on Diego Garcia atoll in the middle of the Indian Ocean.

On December 26, 2004, the countries surrounding the Indian Ocean were hit by a tsunami caused by the 2004 Indian Ocean earthquake. The waves resulted in more than 226,000 deaths and over 1 million were left homeless.

Culture and Literature

See Culture of the Indian Ocean Islands and Indian Ocean literature

Major ports and harbours

See also

Commons
Wikimedia Commons has media related to::
  • Indian Ocean states
  • List of islands in the Indian Ocean

References
ISBN links support NWE through referral fees

  1. ↑ Limits of Oceans and Seas. International Hydrographic Organization Special Publication No. 23, 1953.
  • Braun, D., The Indian Ocean (1983)
  • Chandra, S., ed., The Indian Ocean (1987);
  • Chaudhuri, K. N., Trade and Civilization in the Indian Ocean (1985);
  • Cousteau, Jacques-Yves, and Diole, Philippe, Life and Death in a Coral Sea (1971);
  • Cubitt, Gerald, Islands of the Indian Ocean (1975);
  • Das Gupta, A., and Pearson, M.N., India and the Indian Ocean (1987);
  • Dowdy, W. L., and Trood, R., eds., The Indian Ocean (1985);
  • Kerr, A., ed., Resources and Development in the Indian Ocean Region (1981);
  • Nairn, A. E., and Stehli, F. G., eds., The Ocean Basins and Margins, Vol. 6: The Indian Ocean (1982);
  • Ostheimer, John M., ed., The Politics of the Western Indian Ocean Islands (1975);
  • Torabully, Khal, Coolitude: An Anthology of the Indian Labour Diaspora (with Marina Carter, Anthem Press, London, 2002) ISBN 1843310031
  • Toussaint, Auguste, The History of the Indian Ocean, trans. by June Guicharnaud (1966).

Much of this text is based on public domain text by US Naval Oceanographer at: http://oceanographer.navy.mil/indian.html

External links

Waters of South Asia
Inland
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