It has the fewest seas. It has a peculiar bottom topography, and in the northern part - a special system of winds and sea currents.
Mostly located in the Southern Hemisphere between, and. Its coastline is slightly indented, with the exception of the northern and northeastern parts, where almost all the seas and large bays are located.
Unlike other oceans, the mid-ocean ridges of the Indian Ocean consist of three branches radiating from its central part. The ridges are dissected by deep and narrow longitudinal depressions - grabens. One of these huge grabens is the Red Sea depression, which is a continuation of the faults in the axial part of the Arabian-Indian mid-ocean ridge.
Mid-ocean ridges divide the bed into 3 large sections that are part of three different ones. The transition from the ocean floor to the continents is gradual everywhere, only in the northeastern part of the ocean is the arc of the Sunda Islands, under which the Indo-Australian lithospheric plate plunges. Therefore, a deep-sea trench about 4000 km long stretches along these islands. There are over a hundred active volcanoes, among which the famous - Krakatau, earthquakes often occur.
At the surface of the Indian Ocean depends on the geographical latitude. The northern part of the Indian Ocean is much warmer than the southern part.
Monsoons form in the northern part of the Indian Ocean (to the north of 10 S). In summer, the southwest summer monsoon blows here, carrying moist equatorial air from the sea to land, in winter - the northeast winter monsoon, carrying dry tropical air from the continent.
The system of surface currents in the southern half of the Indian Ocean is similar to the system of currents in the corresponding latitudes of the Pacific and Atlantic oceans. However, north of 10°N. arises special treatment water movements: monsoonal seasonal currents appear, changing direction to the opposite twice a year.
The organic world of the Indian Ocean has much in common with the organic world of the Pacific and Atlantic Oceans in the corresponding latitudes. In the shallow waters of the hot zones, coral polyps are common, creating numerous reef structures, including islands. Among the fish, the most numerous are anchovies, tuna, flying fish, sailfish, and sharks. The tropical coasts of the mainland are often occupied by mangroves. They are characterized by peculiar plants with terrestrial respiratory roots and special animal communities (oysters, crabs, shrimps, mudskipper fish). The bulk of the ocean animals are invertebrate planktonic organisms. Common in tropical coastal areas sea turtles, poisonous sea snakes, endangered mammals - dugongs. Whales, sperm whales, dolphins, and seals live in the cold waters of the southern part of the ocean. Among the birds, the penguins that inhabit the coast are the most interesting. South Africa, Antarctica and temperate ocean islands.
Natural resources and economic development
The Indian Ocean has great biological wealth, but fishing is mostly limited coastal areas, where, in addition to fish, lobsters, shrimps, mollusks are caught. In the open waters of hot zones, tuna is fished, and in cold waters - whales and krill.
Of the most important oil fields and natural gas. The Persian Gulf with the land adjacent to it stands out especially, where 1/3 of the oil of the foreign world is extracted.
In recent decades, the coasts of warm seas and the islands of the northern part of the ocean have become increasingly attractive for people to relax, and the tourism business is booming here. Through the Indian Ocean, the volume of traffic is much less than through the Atlantic and Pacific Ocean s. However, he plays important role in the development of the countries of South and Southeast Asia.
The Indian Ocean has the fewest seas compared to other oceans. The largest seas are located in the northern part: the Mediterranean - the Red Sea and the Persian Gulf, the semi-enclosed Andaman Sea and the marginal Arabian Sea; in the eastern part - the Arafura and Timor seas.
There are relatively few islands. The largest of them are of continental origin and are located near the coast: Madagascar, Sri Lanka, Socotra. In the open part of the ocean, there are volcanic islands - Mascarene, Crozet, Prince Edward, etc. In tropical latitudes, coral islands rise on volcanic cones - Maldives, Laccadive, Chagos, Cocos, most of the Andaman, etc.
Shores in the N.-W. and the East are indigenous, in the S.-V. and the West are dominated by alluvial. The coastline is slightly indented, with the exception of the northern part of the Indian Ocean. Almost all the seas and large bays (Aden, Oman, Bengal) are located here. In the southern part there are the Gulf of Carpentaria, the Great Australian Gulf and the gulfs of Spencer, St. Vincent, etc.
A narrow (up to 100 km) continental shelf (shelf) stretches along the coast, the outer edge of which has a depth of 50-200 m (only near Antarctica and northwestern Australia up to 300-500 m). The continental slope is a steep (up to 10-30°) ledge, locally dissected by the underwater valleys of the Indus, Ganges, and other rivers. m). The bed of the Indian Ocean is divided by ridges, mountains and ramparts into a number of basins, the most significant of which are the Arabian Basin, the West Australian Basin, and the African-Antarctic Basin. The bottom of these basins is formed by accumulative and hilly plains; the first are located near the continents in areas with an abundant supply of sedimentary material, the second - in the central part of the ocean. Among the numerous ridges of the bed, the straightness and length (about 5,000 km) distinguish the meridional East Indian Ridge, which connects in the south with the latitudinal West Australian Ridge; large meridional ridges stretch to the south from the Hindustan peninsula and about. Madagascar. Volcanoes are widely represented on the ocean floor (Mt. Bardina, Mt. Shcherbakov, Mt. Lena, and others), which in places form large massifs (to the north of Madagascar) and chains (to the east of the Cocos Islands). Mid-ocean ridges - mountain system, consisting of three branches diverging from the central part of the ocean to the north (Arabian-Indian ridge), southwest. (West Indian and African-Antarctic ridges) and Yu.-V. (Central Indian Ridge and Australo-Antarctic Rise). This system has a width of 400–800 km, a height of 2–3 km, and is most dissected by an axial (rift) zone with deep valleys and rift mountains bordering them; transverse faults are characteristic, along which horizontal displacements of the bottom up to 400 km are noted. The Australo-Antarctic Rise, in contrast to the median ridges, is a gentler swell 1 km high and up to 1500 km wide.
The bottom sediments of the Indian Ocean are thickest (up to 3-4 km) at the foot of the continental slopes; in the middle of the ocean - small (about 100 m) thickness and in places where the dissected relief is distributed - discontinuous distribution. The most widely represented are foraminiferal (on continental slopes, ridges, and at the bottom of most basins at depths up to 4700 m), diatoms (south of 50° S), radiolarian (near the equator), and coral sediments. Polygenic sediments - red deep-sea clays - are distributed south of the equator at a depth of 4.5-6 km or more. Terrigenous sediments - off the coast of the continents. Chemogenic sediments are mainly represented by iron-manganese nodules, while riftogenic sediments are represented by destruction products of deep rocks. Bedrock outcrops are most often found on continental slopes (sedimentary and metamorphic rocks), mountains (basalts) and mid-ocean ridges, where, in addition to basalts, serpentinites and peridotites were found, representing the little-altered substance of the Earth's upper mantle.
The Indian Ocean is characterized by the predominance of stable tectonic structures both on the bed (thalassocratons) and along the periphery (continental platforms); active developing structures - modern geosynclines (Sonda arc) and georiftogenals (mid-ocean ridge) - occupy smaller areas and continue in the corresponding structures of Indochina and rifts of East Africa. These basic macrostructures, which differ sharply in morphology, structure earth's crust, seismic activity, volcanism, are subdivided into smaller structures: plates, usually corresponding to the bottom of oceanic basins, blocky ridges, volcanic ridges, sometimes crowned with coral islands and banks (Chagos, Maldives, etc.), trench-faults (Chagos, Ob, etc. .), often confined to the foot of blocky ridges (East Indian, West Australian, Maldives, etc.), fault zones, tectonic ledges. Among the structures of the Indian Ocean bed, a special place (according to the presence of continental rocks - granites of the Seychelles and the continental type of the earth's crust) is occupied by the northern part of the Mascarene Range - a structure that is apparently part of ancient mainland Gondwana.
Minerals: on the shelves - oil and gas (especially the Persian Gulf), monazite sands (the coastal region of Southwestern India), etc.; in rift zones - ores of chromium, iron, manganese, copper, etc.; on the bed - huge accumulations of iron-manganese nodules.
The climate of the northern part of the Indian Ocean is monsoonal; in summer, when an area develops over Asia reduced pressure, southwestern flows of equatorial air dominate here, in winter - northeastern flows of tropical air. South of 8-10 ° S sh. atmospheric circulation is much more constant; here, in tropical (summer and subtropical) latitudes, stable southeasterly trade winds dominate, and in temperate latitudes, extratropical cyclones moving from West to East. In tropical latitudes in the western part, hurricanes occur in summer and autumn. The average air temperature in the northern part of the ocean in summer is 25-27 °C, off the coast of Africa - up to 23 °C. In the southern part, it decreases in summer to 20-25 ° C at 30 ° S. sh., up to 5-6 ° С at 50 ° S. sh. and below 0 ° С south of 60 ° S. sh. In winter, the air temperature varies from 27.5 °C near the equator to 20 °C in the northern part, to 15 °C at 30 ° S. sh., up to 0-5 ° С at 50 ° S. sh. and below 0 ° С south of 55-60 ° S. sh. However, in the southern subtropical latitudes all year round the temperature in the West, under the influence of the warm Madagascar Current, is 3-6 °C higher than in the East, where the cold West Australian Current exists. Cloudiness in the monsoon northern part of the Indian Ocean in winter is 10-30%, in summer up to 60-70%. In the summer there is also the largest number precipitation. Medium annual amount precipitation in the east of the Arabian Sea and the Bay of Bengal is more than 3000 mm, near the equator 2000-3000 mm, in the west of the Arabian Sea up to 100 mm. In the southern part of the ocean, the average annual cloudiness is 40-50%, south of 40 ° S. sh. - up to 80%. The average annual precipitation in the subtropics is 500 mm to the east and 1,000 mm to the west; in temperate latitudes, more than 1,000 mm; near Antarctica, it drops to 250 mm.
The circulation of surface waters in the northern part of the Indian Ocean has a monsoonal character: in summer - the northeast and east currents, in winter - the southwest and west currents. During the winter months between 3° and 8° S. sh. an inter-trade (equatorial) countercurrent develops. In the southern part of the Indian Ocean, water circulation forms an anticyclonic circulation, which is formed from warm currents - the South Trade Winds in the north, Madagascar and Needles in the West, and cold currents - the West Winds in the South and the West Australian in the East South of 55 ° S. sh. several weak cyclonic water cycles develop, closing off the coast of Antarctica with an easterly current.
The heat balance is dominated by a positive component: between 10° and 20° N. sh. 3.7-6.5 GJ/(m2×year); between 0° and 10°S sh. 1.0-1.8 GJ/(m2×year); between 30° and 40°S sh. - 0.67-0.38 GJ/(m2×year) [from - 16 to 9 kcal/(cm2×year)]; between 40° and 50°S sh. 2.34-3.3 GJ/(m2×year); south of 50°S sh. -1.0 to -3.6 GJ/(m2×yr) [-24 to -86 kcal/(cm2×yr)]. In the expenditure part of the heat balance north of 50 ° S. sh. the main role belongs to the cost of heat for evaporation, and south of 50 ° S. sh. - heat exchange between the ocean and the atmosphere.
The surface water temperature reaches its maximum (over 29 °C) in May in the northern part of the ocean. In the summer of the Northern Hemisphere, it is 27-28 ° C here, and only off the coast of Africa decreases to 22-23 ° C under the influence of cold waters coming to the surface from the depths. At the equator, the temperature is 26-28 ° C and decreases to 16-20 ° C at 30 ° S. sh., up to 3-5 ° С at 50 ° S. sh. and below -1 ° С south of 55 ° S. sh. In the winter of the Northern Hemisphere, the temperature in the north is 23–25°C, at the equator 28°C, and at 30°S. sh. 21-25 ° С, at 50 ° S sh. from 5 to 9 ° С, south of 60 ° S sh. temperatures are negative. In subtropical latitudes all year round in the West, the water temperature is 3-5 °C higher than in the East.
The salinity of water depends on water balance, which is formed on average for the surface of the Indian Ocean from evaporation (-1380 mm/year), precipitation (1000 mm/year) and continental runoff (70 cm/year). The main flow of fresh water comes from the rivers of South Asia (Ganges, Brahmaputra, etc.) and Africa (Zambezi, Limpopo). The highest salinity is observed in the Persian Gulf (37-39‰), in the Red Sea (41‰) and in the Arabian Sea (more than 36.5‰). In the Bay of Bengal and the Andaman Sea, it decreases to 32.0-33.0‰, in the southern tropics - to 34.0-34.5‰. In the southern subtropical latitudes, salinity exceeds 35.5‰ (maximum 36.5‰ in summer, 36.0‰ in winter), and south of 40°S. sh. drops to 33.0-34.3‰. The highest water density (1027) is observed in the Antarctic latitudes, the lowest (1018, 1022) - in the northeastern part of the ocean and in the Bay of Bengal. In the northwestern part of the Indian Ocean, the density of water is 1024-1024.5. Oxygen content in surface layer water increases from 4.5 ml / l in the northern part of the Indian Ocean to 7-8 ml / l south of 50 ° S. sh. At depths of 200-400 m, the oxygen content according to absolute value much less and varies from 0.21-0.76 in the north to 2-4 ml/l in the south, at greater depths it gradually increases again and in the bottom layer is 4.03-4.68 ml/l. The color of the water is predominantly blue, in the Antarctic latitudes it is blue, in some places with greenish hues.
The tides in the Indian Ocean are usually low (off the coast open ocean and on the islands from 0.5 to 1.6 m), only in the tops of some bays they reach 5-7 m; in the Gulf of Cambay 11.9 m. The tides are predominantly semi-diurnal.
Ice forms at high latitudes and is carried by winds and currents along with icebergs in a northerly direction (up to 55°S in August and up to 65-68°S in February).
The deep circulation and vertical structure of the Indian Ocean is shaped by waters sinking into the subtropical (subsurface waters) and Antarctic (intermediate waters) convergence zones and along continental slope Antarctica (bottom waters), as well as coming from the Red Sea and Atlantic Ocean(deep waters). Subsurface waters have a temperature of 10-18°C at a depth of 100-150 m to 400-500 m, salinity of 35.0-35.7‰, intermediate waters occupy a depth of 400-500 m to 1000-1500 m, have a temperature of 4 to 10°C, salinity 34.2-34.6‰; deep waters at a depth of 1000-1500 m to 3500 m have a temperature of 1.6 to 2.8 ° C, salinity of 34.68-34.78‰; bottom waters below 3500 m in the south have a temperature of -0.07 to -0.24 ° C, salinity 34.67-34.69 ‰, in the north - about 0.5 ° C and 34.69-34.77 ‰ respectively.
Flora and fauna
The entire water area of the Indian Ocean lies within the tropical and southern temperate zones. The shallow waters of the tropical zone are characterized by numerous 6- and 8-ray corals, hydrocorals, capable of creating islands and atolls together with calcareous red algae. The richest fauna of various invertebrates (sponges, worms, crabs, mollusks, sea urchins, ophiurs and sea stars), small but brightly colored coral fish. Most of coasts is occupied by mangroves, in which the mudskipper stands out - a fish capable of long time exist in the air. The fauna and flora of the beaches and rocks that dry out at low tide are quantitatively depleted as a result of the depressing effect of the sun's rays. In the temperate zone, life on such stretches of coasts is much richer; dense thickets of red and brown algae (kelp, fucus, reaching the enormous size of macrocystis) develop here, various invertebrates are abundant. For the open spaces of the Indian Ocean, especially for the surface layer of the water column (up to 100 m), rich flora is also characteristic. Of the unicellular planktonic algae, several species of peredinium and diatom algae predominate, and in the Arabian Sea - blue-green algae, often causing mass development the so-called water bloom.
Copepods (more than 100 species) make up the bulk of the ocean's animals, followed by pteropods, jellyfish, siphonophores, and other invertebrates. Of the unicellular, radiolarians are characteristic; numerous squids. Of the fish, the most abundant are several species of flying fish, luminous anchovies - myctophids, dolphins, large and small tuna, sailfish and various sharks, poisonous sea snakes. Sea turtles and large marine mammals (dugongs, toothed and toothless whales, pinnipeds) are common. Among the birds, the most characteristic are albatrosses and frigates, as well as several species of penguins that inhabit the coasts of South Africa, Antarctica and the islands that lie in the temperate zone of the ocean.
The area of the Indian Ocean exceeds 76 million square kilometers - it is the third largest water area in the world.
From the western part of the Indian Ocean, Africa is comfortably located, from the East - the Sunda Islands and Australia, in the south sparkles Antarctica and in the north is captivating Asia. Peninsula Hindustan divides northern part The Indian Ocean is divided into two parts - the Bay of Bengal and the Arabian Sea.
Borders
The Cape Meridian coincides with the border between the Atlantic and Indian Oceans, and the line that connects the Malaaka Peninsula with the islands of Java, Sumatra and runs along the Southeast Cape meridian south of Tasmania is the border between the Indian and Pacific Oceans.
Geographical position on the map Indian Ocean islands
Here are such famous islands as the Maldives, Seychelles, Madagascar, Cocos Islands, Laccadive, Nicobar, the Chagos Archipelago and Christmas Island.
It is impossible not to mention the group of Mascarene Islands, which are located to the east of Madagascar: Mauritius, Reunion, Rodrigues. And on the south side of the island are Croe, Prince Edward, Kerguelen with beautiful beaches.
Brethren
connects Indian Ocean and the South China Sea Maoakk Strait, between the Indian Ocean and the Java Sea as connective tissue protrudes the Sunda Strait and the Lombok Strait.
From the Gulf of Oman, which is located in the northwest of the Arabian Sea, you can get to the Persian Gulf by sailing through the Strait of Hormuz.
The road to the Red Sea is opened by the Gulf of Aden, which is located a little to the south. The Mozambique Channel separates Madagascar from the African continent.
Basin and list of inflowing rivers
The major rivers of Asia belong to the Indian Ocean basin, such as:
- Indus, which flows into the Arabian Sea,
- Irrawaddy,
- salween,
- Ganges with Brahmaputra going to the Bay of Bengal,
- Euphrates and Tigris, which merge a little above the point of confluence with the Persian Gulf,
- Limpopo and Zambezi major rivers Africa, also fall into it.
The most great depth(maximum - almost 8 kilometers) of the Indian Ocean was measured in the Yavan (or Sunda) deep-sea trench. The average depth of the ocean is almost 4 kilometers.
It is washed by many rivers. Under the influence of seasonal changes in monsoon winds, surface currents in the north of the ocean change.
In winter, monsoons blow from the northeast, and in summer from the southwest. Currents south of 10°S tend to move counterclockwise.
In the ocean south, currents move east from the west, while the South Equatorial Current (north of 20°S) moves in the opposite direction. The equatorial countercurrent, which is located immediately south of the equator itself, carries water to the east.
Photo, view from the plane Etymology
The Eritrean Sea - that's what the ancient Greeks called western part Indian Ocean with the Persian and Arabian Gulfs. Over time, this name began to be identified only with the nearest sea, and the ocean itself was named after India, which was very famous for its wealth among all the countries that are located off the coast of this ocean.
In the fourth century BC, Alexander Macdonsky called the Indian Ocean Indicon Pelagos (which means "Indian Sea" in ancient Greek). The Arabs called it Bar-el-Khid.
In the 16th century, the Roman scientist Pliny the Elder introduced the name, which has stuck to this day: Oceanus Indicus, (which in Latin corresponds to the modern name).
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Less extensive than Quiet and. Its area is 76 million km2. This ocean is widest in the Southern Hemisphere, and in the Northern Hemisphere it looks like a large sea, deeply cutting into the land. It was the large sea that the Indian Ocean was presented to people from ancient times up to.
The shores of the Indian Ocean are one of the areas of ancient civilizations. Scientists believe that navigation in it began earlier than in other oceans, about 6 thousand years ago. The Arabs were the first to describe ocean routes. The accumulation of information about the Indian Ocean began from the time of the voyage (1497-1499). AT late XVIII century, the first measurements of its depths were made by an English navigator. The comprehensive study of the ocean began in late XIX century. The largest studies were carried out by the British expedition on board the Challenger. Nowadays, dozens of expeditions from different countries are studying the nature of the ocean, revealing its riches.
The average depth of the ocean is about 3700 meters, and the maximum reaches 7729 meters in the Yavan Trench. An underwater ridge stretches in the western part of the ocean, connecting to the south with the Mid-Atlantic Ridge. Deep faults, areas and at the bottom of the ocean are confined to the center of the ridge in the Indian Ocean. These faults continue into and out on land. The ocean floor is crossed by numerous uplifts.
Location: The Indian Ocean is bounded from the north by Eurasia, from the west by the east coast of Africa, from the east by the western coast of Oceania, and from the south by the waters South Sea, the border of the Atlantic and Indian Oceans runs along the 20th meridian of E. D., between the Indian and Pacific Oceans - along the 147th meridian of E. d.
Square: 74.7 million km2
Average depth: 3 967 m.
Maximum depth: 7729 m (Zonda, or Yavansky, trench).
: from 30‰ to 37‰.
Additional Information : in the Indian Ocean there are islands, Sri Lanka, Socotra, Laccadive, Maldives, Andaman and Nicobar, Comoros, and some others.
The Indian Ocean is smaller in area than the Pacific. Its water area occupies 76 million square kilometers. It is located almost entirely in the southern hemisphere. In ancient times, people considered it a great sea.
by the most large islands The Indian Ocean are Sri Lanka, Madagascar, Masirai, Kuria-Muria, Socotra, Greater Sunda, Seychelles, Nicobar, Andanam, Coconut, Amirant, Chagos, Maldives, Laccadive.
The coast of the Indian Ocean - the places where ancient civilizations were located. Scientists believe that navigation in this ocean began earlier than in others, about 6 thousand years ago. The first to describe ocean routes were the Arabs. The accumulation of navigational information about the Indian Ocean began as early as the travels of Vasco de Gama (1497-1499). At the end of the 18th century, the first measurements of its depths were made by the English navigator James Cook.
A detailed study of the ocean began at the end of the 19th century. The most extensive study was carried out by the British research team on board the Challenger. At the moment, dozens of research expeditions from different countries are studying the nature of the ocean, revealing its riches.
The average depth of the Indian Ocean is about 3,700 meters, and the maximum is 7,700 meters. In the western part of the ocean, seamounts are located, connecting in a place located south of the Cape of Good Hope, with the Mid-Atlantic Ridge. Near the center of the ridge in the Indian Ocean are deep faults, areas seismic activity and volcanic eruptions on the ocean floor. These faults stretch to the Red Sea and come out on land. The bottom of the ocean is crossed by numerous hills.
If the Pacific Ocean inspires with its blue color, then the Indian Ocean is known for the transparency of its dark blue and azure waters. This is due to the cleanliness of the ocean, as little fresh water from the rivers - "disturbers of purity", especially in its southern part.
The Indian Ocean is saltier than other oceans. This is especially noticeable in the northwestern part of the ocean, where high temperatures hot air masses from the Sahara are added to the water. The record holder for salt content is the Red Sea (up to 42%) and the Persian Gulf.
The northern part of the Indian Ocean is heavily influenced by land; it rightfully deserves the name "monsoon sea". AT winter time dry air comes from the largest continent - Eurasia. In summer, the situation changes dramatically. The heated ocean saturates the air large quantity moisture. Then, moving to the mainland, it breaks out over the south of the continent with heavy rains. Before the summer monsoon winds, thunderstorms pass, generating sea swell, carried by the wind to the southwestern coast of India. In autumn and spring, typhoons form in the northern part of the Indian Ocean, bringing many problems to the inhabitants of the shores of the Arabian Sea and the Bay of Bengal, as well as to sailors. In the south of the Indian Ocean, you can feel the cold breath of Antarctica, in these places the ocean is the most severe.
Indian Ocean forms good conditions for coral life. Their large colonies are located in the Maldives, located south of the Hindustan peninsula. These islands are by composition the longest coral islands in the world.
The Indian Ocean is rich in its fish resources, which have been used by man since ancient times. For many residents of the coast, fishing is the only source of income.
Since time immemorial, pearls have been mined in these places. The coast of the island of Sri Lanka since ancient times served as a place for the extraction of emeralds, diamonds, emeralds and many other types of precious stones.
Under the bottom of the Persian Gulf, located in the northwestern part of the Indian Ocean, gas and oil reserves have been formed for thousands of years.
