Where is the Indian Ocean deepest? Geographical location of the Indian Ocean: description, features. Indian Ocean on the map
home Indian Ocean
by volume makes up 20% of the World Ocean. It is bounded by Asia to the north, Africa to the west and Australia to the east.
In the zone 35° S. passes the conventional border with the Southern Ocean.
Description and characteristics
The waters of the Indian Ocean are famous for their transparency and azure color. The fact is that few freshwater rivers, these “troublemakers,” flow into this ocean. Therefore, by the way, the water here is much saltier than in others. It is in the Indian Ocean that the saltiest sea in the world, the Red Sea, is located.
The ocean is also rich in minerals. The area near Sri Lanka has been famous for its pearls, diamonds and emeralds since ancient times. And the Persian Gulf is rich in oil and gas.
Area: 76.170 thousand sq. km
Volume: 282.650 thousand cubic km
Average depth: 3711 m, greatest depth - Sunda Trench (7729 m). average temperature
: 17°C, but in the north the waters warm up to 28°C.
Currents: two cycles are conventionally distinguished - northern and southern. Both move clockwise and are separated by the Equatorial Countercurrent.
Main currents of the Indian Ocean
Warm: Northern Passatnoye
- originates in Oceania, crosses the ocean from east to west. Beyond the peninsula, Hindustan is divided into two branches. Part flows to the north and gives rise to the Somali Current. And the second part of the flow heads south, where it merges with the equatorial countercurrent. South Passatnoye
- begins at the islands of Oceania and moves from east to west all the way to the island of Madagascar. Madagascar
- branches off from the South Passat and flows parallel to the Mozambique from north to south, but slightly east of the Madagascar coast. Average temperature: 26°C. Mozambican
- another branch of the South Trade Wind Current. It washes the coast of Africa and in the south merges with the Agulhas Current. Average temperature - 25°C, speed - 2.8 km/h. Agulhas, or Cape Agulhas Current - narrow and fast current , passing along east coast
Africa from north to south.
Cold: Somali
- a current off the coast of the Somali Peninsula, which changes its direction depending on the monsoon season. Current of the West Winds encircles Earth
Western Australian- moves from south to north along the western coast of Australia. As you approach the equator, the water temperature rises from 15°C to 26°C. Speed: 0.9-0.7 km/h.
The underwater world of the Indian Ocean
Most of the ocean is located in subtropical and tropical zones, and therefore rich and diverse in species.
The tropical coast is represented by vast thickets of mangroves, home to numerous colonies of crabs and amazing fish- mudskippers. Shallow waters provide excellent habitat for corals. And in temperate waters brown, calcareous and red algae grow (kelp, macrocysts, fucus).
Invertebrate animals: numerous mollusks, a huge number of species of crustaceans, jellyfish. There are many sea snakes, especially poisonous ones.
Sharks of the Indian Ocean are the special pride of the water area. This is where the most a large number of types of sharks: blue, gray, tiger, great white, mako, etc.
Of the mammals, the most common are dolphins and killer whales. A South part the ocean is natural environment habitat of many species of whales and pinnipeds: dugongs, fur seals, seals. The most common birds are penguins and albatrosses.
Despite the richness of the Indian Ocean, seafood fishing here is poorly developed. The catch is only 5% of the world's. Tuna, sardines, stingrays, lobsters, lobsters and shrimp are caught.
Indian Ocean exploration
The coastal countries of the Indian Ocean are centers of ancient civilizations. That is why the development of the water area began much earlier than, for example, the Atlantic or Pacific Ocean. Approximately 6 thousand years BC. The waters of the ocean were already plied by the shuttles and boats of ancient people. The inhabitants of Mesopotamia sailed to the shores of India and Arabia, the Egyptians conducted a lively maritime trade with the countries of East Africa and the Arabian Peninsula.
Key dates in the history of ocean exploration:
7th century AD - Arab sailors compiled detailed navigation maps coastal zones Indian Ocean, exploring the waters near the eastern coast of Africa, India, the islands of Java, Ceylon, Timor, and the Maldives.
1405-1433 - seven sea travel Zheng He and the study of trade routes in the northern and eastern parts of the ocean.
1497 - Vasco de Gama's voyage and exploration of the eastern coast of Africa.
(Expedition of Vasco de Gama in 1497)
1642 - two raids by A. Tasman, exploration of the central part of the ocean and discovery of Australia.
1872-1876 - the first scientific expedition of the English corvette Challenger, studying the biology of the ocean, relief, and currents.
1886-1889 - expedition of Russian explorers led by S. Makarov.
1960-1965 - international Indian Ocean expedition established under the auspices of UNESCO. Study of hydrology, hydrochemistry, geology and ocean biology.
1990s - present day: studying the ocean using satellites, compiling a detailed bathymetric atlas.
2014 - after the crash of a Malaysian Boeing, detailed mapping of the southern part of the ocean was carried out, new underwater ridges and volcanoes were discovered.
The ancient name of the ocean is Eastern.
Many species of wildlife in the Indian Ocean have an unusual property - they glow. In particular, this explains the appearance of luminous circles in the ocean.
In the Indian Ocean, ships are periodically found in good condition, however, where the entire crew disappears remains a mystery. Over the last century, this happened to three ships at once: the Cabin Cruiser, the tankers Houston Market and Tarbon.
The Indian Ocean occupies a smaller area than the Pacific Ocean. Its water area covers 76 million square kilometers. It is almost entirely located in the southern hemisphere. In ancient times, people considered it a large sea.
The most large islands The Indian Ocean are Sri Lanka, Madagascar, Masirai, Kuria-Muria, Socotra, Greater Sunda, Seychelles, Nicobar, Andanaman, Coconut, Amirantha, Chagos, Maldives, Laccadive.
The coast of the Indian Ocean is where ancient civilizations were located. Scientists believe that navigation in this ocean began earlier than in others, approximately 6 thousand years ago. The first to describe ocean routes were the Arabs. The accumulation of navigational information about the Indian Ocean began from the time of the travels of Vasco de Gama (1497-1499). IN late XVIII centuries, the first measurements of its depths were carried out by the English navigator James Cook.
Detailed study of the ocean began in late XIX century. The most extensive study has been carried out by English research group on the Challenger ship. 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 there are seamounts that connect at a point south of the Cape of Good Hope with the Mid-Atlantic Ridge. Near the center of the ridge in the Indian Ocean there are deep faults, areas of seismic activity and volcanic eruptions on the ocean floor. These faults extend to the Red Sea and reach land. The ocean floor is crossed by numerous hills.
While the Pacific Ocean inspires with its blue color, the Indian Ocean is known for the transparency of its dark blue and azure waters. This is due to the purity of the ocean, since little fresh water flows into the ocean from 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 Indian Ocean is heavily influenced by land; it rightfully deserves the name “monsoon sea”. In winter, dry air comes from the largest continent - Eurasia. In summer the situation changes dramatically. The warming ocean saturates the air big amount moisture. Then moving to the mainland it breaks out over the south of the continent with heavy rains. Before the summer monsoon winds, thunderstorms occur, generating sea swells that are carried by the wind to the southwestern coast of India. In autumn and spring, typhoons form in the northern part of the Indian Ocean, causing many problems for residents of the shores of the Arabian Sea and the Bay of Bengal, as well as for sailors. In the south of the Indian Ocean you can feel the cold breath of Antarctica; in these places the ocean is the harshest.
Indian Ocean shapes good conditions for coral life. Their large colonies are located in the Maldives, located south of the Hindustan Peninsula. These islands are, by their 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 coastal residents, fishing is the only source of income.
Since time immemorial, pearls have been mined in these places. The coast of the island of Srilanka has served as a mining site for emeralds, diamonds, emeralds and many other types of precious stones since ancient times.
Beneath the floor of the Persian Gulf, located in the northwestern part of the Indian Ocean, gas and oil reserves have been forming for thousands of years.
The Indian Ocean has the least number of seas compared to other oceans. In the northern part there are the largest seas: 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 coasts of 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 - the Maldives, Laccadives, Chagos, Cocos, most Andaman, etc.
Shores on the north-west. and the East are indigenous, in the north-east. and in the West, alluvial deposits predominate. The coastline is slightly indented, with the exception of the northern part of the Indian Ocean. Almost all 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 in Antarctica and northwestern Australia up to 300-500 m). The continental slope is a steep (up to 10-30°) ledge, in places dissected by the underwater valleys of the Indus, Ganges and other rivers. In the northeastern part of the ocean there is the Sunda Island Arc and the Sunda Trench associated with it, which is associated with maximum depths (up to 7130 m). The bed of the Indian Ocean is divided by ridges, mountains and swells into a number of basins, the most significant of which are the Arabian Basin, the Western Australian Basin, and the African-Antarctic Basin. The bottom of these basins is formed by accumulative and hilly plains; the former are located near continents in areas with an abundant supply of sedimentary material, the latter - in the central part of the ocean. Among the numerous ridges of the bed, the meridional East Indian Ridge, which connects in the south with the latitudinal Western Australian Ridge, stands out due to its straightness and length (about 5,000 km); large meridional ridges stretch south from the Hindustan Peninsula and the island. Madagascar. Volcanoes are widely represented on the ocean floor (Mt. Bardina, Mt. Shcherbakova, Mt. Lena, etc.), which in some places form large massifs (to the north of Madagascar) and chains (to the east of the Cocos Islands). Mid-ocean ridges are a 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 South-East. (Central Indian Ridge and Australian-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; Characterized by transverse faults, along which horizontal displacements of the bottom up to 400 km are noted. The Australian-Antarctic Rise, in contrast to the median ridges, is a more gentle swell 1 km high and up to 1500 km wide.
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 dissected relief is distributed - intermittent distribution. The most widely represented are foraminifera (on continental slopes, ridges and on the bottom of most basins at depths of up to 4700 m), diatoms (south of 50° S), radiolarians (near the equator) and coral sediments. Polygenic sediments - red deep-sea clays - are common south of the equator at a depth of 4.5-6 km or more. Terrigenous sediments - off the coast of continents. Chemogenic sediments are represented mainly by iron-manganese nodules, and riftogenic sediments are represented by products of destruction of deep rocks. Outcrops of bedrock 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, representing the slightly altered material of the Earth's upper mantle, were found.
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 (Sunda arc) and georiftogenals (mid-ocean ridge) - occupy smaller areas and are continued in the corresponding structures of Indochina and rifts East Africa. These main macrostructures, sharply different in morphology, structure earth's crust, seismic activity, volcanism, are divided into smaller structures: plates, usually corresponding to the bottom of oceanic basins, block ridges, volcanic ridges, in places topped with coral islands and banks (Chagos, Maldives, etc.), fault trenches (Chagos, Obi, etc. .), often confined to the foot of blocky ridges (East Indian, Western Australian, Maldives, etc.), fault zones, tectonic ledges. Among the structures of the Indian Ocean bed, a special place (in terms of the presence of continental rocks - granites of the Seychelles Islands and the continental type of the earth's crust) is occupied by the northern part of the Mascarene Ridge - a structure that is, apparently, part of the ancient continent of Gondwana.
Minerals: on the shelves - oil and gas (especially the Persian Gulf), monazite sands (coastal region of South-West India), etc.; in rift zones - ores of chromium, iron, manganese, copper, etc.; on the bed there are huge accumulations of iron-manganese nodules.
The climate of the northern Indian Ocean is monsoonal; in summer, when an area of low pressure develops over Asia, southwestern flows of equatorial air dominate here, in winter - northeastern flows of tropical air. To the south 8-10° S. w. atmospheric circulation is much more constant; Here, in tropical (summer and subtropical) latitudes, stable southeastern trade winds dominate, and in temperate latitudes, extratropical cyclones moving from West to East dominate. In tropical latitudes in the western part there are hurricanes 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 drops in summer to 20-25 °C at 30° S. latitude, up to 5-6 °C at 50° S. w. and below 0 °C south of 60 ° S. w. In winter, the air temperature varies from 27.5 °C at the equator to 20 °C in the northern part, to 15 °C at 30 ° S. latitude, up to 0-5 °C at 50° S. w. and below 0 °C south of 55-60 ° S. w. Moreover, in 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 Western Australian Current exists. Cloudiness in the monsoon northern part of the Indian Ocean is 10-30% in winter, up to 60-70% in summer. In summer there is also greatest number precipitation. The average annual precipitation in the east of the Arabian Sea and the Bay of Bengal is more than 3000 mm, at 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. w. - up to 80%. The average annual precipitation in the subtropics is 500 mm in the east, 1000 mm in the west, in temperate latitudes it is more than 1000 mm, and near Antarctica it drops to 250 mm.
Circulation surface waters in the northern part of the Indian Ocean it has a monsoon character: in summer - northeastern and eastern currents, in winter - southwestern and western currents. IN winter months between 3° and 8° S. w. The inter-trade wind (equatorial) countercurrent develops. In the southern part of the Indian Ocean, water circulation forms an anticyclonic circulation, which is formed from warm currents - the Southern Trade Winds in the north, Madagascar and Agulhas in the West and cold currents - the Western Winds current in the South and Western Australian in the East. South of 55° S. w. Several weak cyclonic water circulations develop, closing off the coast of Antarctica with an eastern current.
The positive component predominates in the heat balance: between 10° and 20° N. w. 3.7-6.5 GJ/(m2×year); between 0° and 10° S. w. 1.0-1.8 GJ/(m2×year); between 30° and 40° S. w. - 0.67-0.38 GJ/(m2×year) [from - 16 to 9 kcal/(cm2×year)]; between 40° and 50° S. w. 2.34-3.3 GJ/(m2×year); south of 50° S. w. from -1.0 to -3.6 GJ/(m2×year) [from -24 to -86 kcal/(cm2×year)]. In the expenditure part of the heat balance north of 50° S. w. the main role belongs to the loss of heat for evaporation, and south of 50° south. w. - heat exchange between the ocean and the atmosphere.
Surface water temperatures reach a 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 it 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° south. latitude, up to 3-5 °C at 50° S. w. and below -1 °C south of 55° S. w. In the winter of the Northern Hemisphere, the temperature in the north is 23-25 °C, at the equator 28 °C, at 30 ° S. w. 21-25 °C, at 50° S. w. from 5 to 9 °C, south of 60° S. w. 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 the 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). Main drain fresh water are given by 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 southern subtropical latitudes, salinity exceeds 35.5‰ (maximum 36.5‰ in summer, 36.0‰ in winter), and to the south 40° S. w. decreases to 33.0-34.3‰. The highest water density (1027) is observed in 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. The oxygen content in the surface layer of water increases from 4.5 ml/l in the northern part of the Indian Ocean to 7-8 ml/l south of 50° south. w. At depths of 200-400 m, the oxygen content in absolute value is significantly lower 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 Antarctic latitudes it is blue, in places with greenish tints.
Tides in the Indian Ocean, as a rule, are small (off the coast of the open ocean and on the islands from 0.5 to 1.6 m), only at the tops of some bays they reach 5-7 m; in the Gulf of Cambay 11.9 m. The tides are predominantly semidiurnal.
Ice forms in 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 are formed by waters plunging in the subtropical (subsurface waters) and Antarctic (intermediate waters) convergence zones and along the continental slope of Antarctica (bottom waters), as well as coming from the Red Sea and Atlantic Ocean(deep waters). At a depth of 100-150 m to 400-500 m, subsurface waters have a temperature of 10-18°C, a salinity of 35.0-35.7‰, intermediate waters occupy a depth of 400-500 m to 1000-1500 m, and have a temperature of 4 to 10°C, salinity 34.2-34.6‰; deep waters at depths from 1000-1500 m to 3500 m have a temperature of 1.6 to 2.8 ° C, salinity 34.68-34.78‰; Bottom waters below 3500 m have a temperature from -0.07 to -0.24 ° C in the South, a salinity of 34.67-34.69‰, in the North - about 0.5 ° C and 34.69-34.77 ‰ respectively.
Flora and fauna
The entire Indian Ocean lies within the tropical and southern temperate zones. For shallow waters tropical zone Characterized by numerous 6- and 8-rayed corals, hydrocorals, capable of creating islands and atolls together with calcareous red algae. Among the powerful coral structures lives a rich fauna of various invertebrates (sponges, worms, crabs, mollusks, sea urchins, brittle stars and starfish), small but brightly colored coral fish. Most of the coasts are occupied by mangroves, in which the mudskipper stands out - a fish that can exist in the air for a long time. The fauna and flora of beaches and rocks that dry out at low tide are quantitatively depleted as a result of the depressing effect of sunlight. IN temperate zone life on such sections of the coast is much richer; dense thickets of red and brown algae(kelp, fucus reaching enormous sizes macrocystis), a variety of invertebrates are abundant. The open spaces of the Indian Ocean, especially the surface layer of the water column (up to 100 m), are also characterized by a rich flora. Among unicellular planktonic algae, several species of peredinium and diatom algae predominate, and in the Arabian Sea - blue-green algae, which often cause so-called water blooms when they develop en masse.
The bulk of ocean animals are copepod crustaceans (more than 100 species), followed by pteropods, jellyfish, siphonophores and other invertebrate animals. The most common unicellular organisms are radiolarians; Squids are numerous. Of the fish, the most abundant are several species of flying fish, luminous anchovies - myctophids, coryphaenas, large and small tuna, sailfish and various sharks, poisonous sea snakes. Distributed sea turtles and large marine mammals (dugongs, toothed and toothless whales, pinnipeds). Among the birds, the most characteristic are albatrosses and frigatebirds, as well as several species of penguins that inhabit the coasts South Africa, Antarctica and islands lying in the temperate zone of the ocean.
Indian Ocean ranks third in area and volume of water. It occupies 1/5 of the area of the World Ocean and 1/7 of the surface of the planet (Fig. 1).
Rice. 1. Indian Ocean on the map.
Square Indian Ocean - 76.17 million km 2. Unlike the Pacific and Atlantic Oceans, it has a small number of seas, only 5. Temperature The surface layer of water is +17 °C, and the salinity is 36.5 ‰. The saltiest part of the Indian Ocean is the Red Sea, with a salinity of 41‰. Relief The Indian Ocean is unique: on the ocean floor there are 10 main basins, 11 underwater ridges and 1 trench more than 6 thousand meters deep.
Average depth The Indian Ocean is 3711 m, and the maximum is 7729 m. The coastline of the Indian Ocean is very slightly indented. Remember the location of the Indian Ocean objects: the Red Sea (Fig. 3), the Gulf of Aden, the Persian Gulf (Fig. 2), the Arabian Sea, the Bay of Bengal, the Greater Sunda Islands archipelago and the Mozambique Strait.
The most characteristic geographical feature The Indian Ocean is that 84% of its area is located in Southern Hemisphere, and there is no direct connection with the Arctic Ocean.
Rice. 2. Persian Gulf
Rice. 3. Red Sea
According to modern data, the western border of the Indian Ocean is the meridian of 20° east. on the stretch between Antarctica and Cape Agulhas in southern Africa. In the northeast, its border runs along the shores of Asia to the Strait of Malacca along the islands of Sumatra, Java, Timor, and New Guinea. Further east through the Torres Strait along the west coast of Australia and the island of Tasmania. Further along 147° E. to Antarctica. Southern border ocean is the coast of Antarctica from 20° east. long up to 147° east. d. Northern border - the southern coast of Eurasia.
History of ocean exploration
The shores of the Indian Ocean are one of the areas of ancient civilizations. The exploration of the ocean began from the north by Indian, Egyptian and Phoenician sailors, who 3 thousand years BC. e. sailed in the Arabian and Red Seas and the Persian Gulf. The first descriptions of voyage routes in the Indian Ocean were written by the Arabs. For European geographical science, information about the ocean began to accumulate since the voyages Vasco da Gama(1497–1499) (Fig. 4), who, having rounded Africa, reached India.
In 1642–1643 Abel Tasman(Fig. 5) first passed from the Indian Ocean to the Pacific along the southern coast of Australia.
At the end of the 18th century, the first depth measurements were carried out here James Cook(Fig. 6).
A comprehensive and systematic study of the ocean began at the end of the 19th century with the circumnavigation of the English expedition on the Challenger ship (Fig. 7).
However, by the middle of the 20th century, the Indian Ocean was very poorly studied. In the 50s The Soviet expedition began work on the Ob ship (Fig. 8).
Today the Indian Ocean is being studied by dozens of expeditions different countries.
Lithospheric plates
At the bottom of the Indian Ocean there is a boundary of three lithospheric plates: African, Indo-Australian and Antarctic (Fig. 9). In the depression of the earth's crust occupied by the waters of the Indian Ocean, all major structural reliefs are clearly expressed ocean floor: shelf (accounting for more than 4% of total area ocean), continental slope, ocean floor (ocean plains and basins, 56% of the total ocean area), mid-ocean ridges (17%), mountain ranges and underwater plateaus, deep-sea trench.
Rice. 9. Lithospheric plates on the map
Mid-ocean ridges divide the ocean floor into three large parts. The transition from the ocean floors to the continents is smooth, only in the northeastern part does the Sunda Islands arc form, under which the Indo-Australian lithospheric plate subducts. In this place, a deep-sea trench 4 thousand km long is formed. The deep Sunda Trench, like the underwater ridges, is a zone of active underwater volcanism and earthquakes.
Geological history of the ocean
Depression Indian Ocean is very young. It was formed about 150 million years ago as a result of the collapse of Gondwana and the moving apart of Africa, Australia, Antarctica and Hindustan. The Indian Ocean acquired its contours close to modern ones about 25 million years ago. Now the ocean is located within three lithospheric plates: African, Indo-Australian and Antarctic.
Climate
The Indian Ocean is located in the tropical and subequatorial zones of the Northern Hemisphere, as well as in all climatic zones Southern Hemisphere. In terms of surface water temperatures, this is the most warm ocean. Temperature Indian Ocean depends on geographical latitude: The northern part of the ocean is warmer than the southern part. Monsoons also form in the northern Indian Ocean. The Indian Ocean washes the shores of the largest continent - Eurasia. Their interaction determines the features of surface currents and atmospheric circulation over the northern part of the ocean and south coast Asia. In winter, an area of high atmospheric pressure, and above the ocean there is an area of low pressure. Thus, a wind is formed - the northeast monsoon. In summer, on the contrary, the southwest monsoon forms.
Sailors have long known the changing nature of the winds and currents of the northern part of the Indian Ocean and skillfully used it while sailing on sailing ships. In Arabic, “monsoon” means “season”, and “breeze” in French means “light wind”. Small sailing ships in the northern Indian Ocean are still in use today.
Tsunami
Underwater earthquake in the Indian Ocean that occurred December 26, 2004, caused a tsunami that was considered the deadliest natural disaster V modern history. The magnitude of the earthquake, according to various sources, ranged from 9.1 to 9.3. This is the second or third strongest earthquake on record. The epicenter of the earthquake was in the Indian Ocean north of the island of Simeulue, located off the northwestern coast of the island of Sumatra (Indonesia). The tsunami reached the shores of Indonesia, Sri Lanka, southern India, Thailand and other countries. The height of the waves exceeded 15 meters. The tsunami caused enormous destruction and a huge number dead people even in Port Elizabeth, South Africa, 6 thousand 900 km from the epicenter (Fig. 10).
Rice. 10. After the earthquake, December 2004
According to various estimates, from 225 to 300 thousand people died. The true death toll is unlikely to ever be known, as many people were swept out to sea.
Flora and fauna
Flora and fauna The Indian Ocean is quite rich. In the shallow waters of the tropical zone, corals grow, which create islands with red and green algae. Among the coral islands, the most famous are Maldives(Fig. 11). These robust coral structures are home to many species of invertebrates such as crabs, sea urchins, sponges, and coral fish. There are huge areas of dense thickets of brown algae here. The open ocean is mostly inhabited by planktonic algae, while the Arabian Sea is characterized by blue-green algae, which constantly cause water blooms.
Rice. 11. Maldives
Also rich and animal world ocean. For example, among the animal waters of the Indian Ocean, the most common crustaceans are copepods, and siphonophores And jellyfish. Squids and some types of flying fish live in the ocean. White shark, sailfish, poisonous sea snake, whales, turtles, seals (Fig. 12). The most common birds are frigates and albatrosses.
Rice. 12. Undersea world Indian Ocean
The flora and fauna of the Indian Ocean is very diverse and interesting, as animals and plants live in a place favorable for development. This is a flower garden for nature lovers, environmentalists and tourists. Oil is produced on the Indian Ocean shelf and natural gas. The most famous place in the world for oil production is the Persian Gulf. The Indian Ocean is considered to be the most polluted by oil compared to other oceans. There are also many shipping routes in the Indian Ocean; there are large port cities and various places of recreation and tourism: Karachi, Dar es Salaam, Maputo, Mumbai, etc.
Bibliography
1. Geography. Land and people. 7th grade: Textbook for general education. uch. / A.P. Kuznetsov, L.E. Savelyeva, V.P. Dronov, “Spheres” series. – M.: Education, 2011.
2. Geography. Land and people. 7th grade: atlas, “Spheres” series.
1. Internet portal "Complete Encyclopedia" ()
2. Internet portal "Geography" ()
3. Internet portal "All about sharks" ()
Ocean area – 76.2 million sq. km;
Maximum depth – Sunda Trench, 7729 m;
Number of seas – 11;
The most big seas– Arabian Sea, Red Sea;
The largest bay is the Bay of Bengal;
The largest islands are the island of Madagascar, Sri Lanka;
The strongest currents:
- warm - South Passatnoe, Monsoon;
- cold - Western Winds, Somali.
The Indian Ocean ranks third in size. Most of it is located in the Southern Hemisphere. In the north it washes the shores of Eurasia, in the west – Africa, in the south – Antarctica, and in the east – Australia. The coastline of the Indian Ocean is slightly indented. On the northern side, the Indian Ocean is seemingly shrouded in land, making it the only ocean that is not connected to the Arctic Ocean.
The Indian Ocean was formed as a result of the splitting of the ancient continent of Gondwana into parts. It lies on the boundary of three lithospheric plates - the Indo-Australian, African and Antarctic. The mid-ocean ridges of the Arabian-Indian, West Indian and Australian-Antarctic are the boundaries between these plates. Underwater ridges and elevations divide the ocean floor into separate basins. The ocean shelf zone is very narrow. Most of the ocean lies within the boundaries of the bed and has considerable depth.
From the north, the Indian Ocean is reliably protected by mountains from the penetration of cold air masses. Therefore, the temperature of surface waters in the northern part of the ocean reaches +29 ˚С, and in the summer in the Persian Gulf it rises to +30...+35 ˚С.
An important feature of the Indian Ocean is the monsoon winds and the monsoon current created by them, which changes its direction seasonally. Hurricanes are frequent, especially around the island of Madagascar.
The coldest areas of the ocean are in the south, where the influence of Antarctica is felt. Icebergs are found in this part of the Pacific Ocean.
The salinity of surface waters is higher than in the World Ocean. The salinity record was recorded in the Red Sea – 41%.
The organic world of the Indian Ocean is diverse. Tropical water masses rich in plankton. The most common fish include: sardinella, mackerel, tuna, mackerel, flounder, flying fish and numerous sharks.
The shelf areas and Coral reefs. In the warm waters of the Pacific Ocean there are giant sea turtles, sea snakes, a lot of squid, cuttlefish, starfish. Whales and seals are found closer to Antarctica. Pearls are mined in the Persian Gulf near the island of Sri Lanka.
Across the Indian Ocean for the most part in its northern part there are important shipping routes. Dug at the end of the 19th century, the Suez Canal connects the Indian Ocean with Mediterranean Sea.
The first information about the Indian Ocean was collected 3 thousand years BC by Indian, Egyptian and Phoenician sailors. The first sailing routes in the Indian Ocean were drawn up by the Arabs.
Vasco da Gama, after the discovery of India in 1499, Europeans began to explore the Indian Ocean. During an expedition, the English navigator James Cook made the first measurements of the depth of the ocean.
A comprehensive study of the nature of the Indian Ocean begins at the end of the nineteenth century.
Nowadays, the warm waters and picturesque coral islands of the Indian Ocean, which attract the attention of tourists from around the world, are carefully studied by numerous scientific expeditions from all over the world.