Indian Ocean- this is the very ocean, the depths of which keep many mysteries and secrets. Although Indonesia is washed by two oceans - the Pacific and the Indian, only the second belongs to Bali. It is the Indian Ocean that the surf spots of the island belong to. Since “you need to know your heroes by sight”, we have collected as many more facts about this ocean, some of them are amazing.
General information
The area of the Indian Ocean is about one fifth of the total area of our planet, it washes 4 parts of the world out of 6 possible at once: Australia, Africa, Asia and even Antarctica. The ocean covers 57 groups of islands, 16 countries in Africa and 18 in Asia. It is the youngest and warmest ocean in the world.
During the great discoveries in the 1500s, the Indian Ocean gained status as one of the most important transport routes. First of all, this was due to the desire of Europeans to gain access to India, where jewelry, rice, cotton, chic fabrics and much more were actively purchased. It is the Indian Ocean that connects the largest number of the most important ports in the world. By the way, it is in the Indian Ocean that about 40% of the world's oil is found. Loot comes second natural gas(according to research, the reserves amount to about 2.3 trillion cubic meters).
Indian Ocean and surfing
The most popular destinations are:
Indonesia. Surfing began about 80 years ago when American photographer Robert Coke decided to found the Kuta Beach hotel. During the events associated with World War II and Indonesia's struggle for independence, surfing was forgotten. But the insatiable Australians on home spots revived surfing in the 1960s. Countless islands led by Bali have made Indonesia the most popular surfing country in Asia. Sumatra (pictured above), Sumbawa, Java, Mentwai, Lombok, Nias, Timor - this is just a small part of the places where your vacation will definitely not be “beach”.
Sri Lanka. Surfers sailed here only in 1970. Unfortunately, the happiness did not last long, as the civil war broke out in 1983. After some time, when peace reigned, the waves began to delight surfers again. But in 2006, the island was literally destroyed by a tsunami that killed about 200,000 people. Renovation work continue to this day, but tourism and surfing is returning and gaining momentum. Of course, there are much fewer surf spots than even in Bali - there are about 3 main surf spots here.
India. History is silent about who and when decided to catch their first wave. Although many people associate India only with cows, yoga and endless meditation, surfing has a place to be. There are about 20 surf spots in the south, but getting to the waves is not that easy. Since surfing in India is not yet as popular as local population speaks almost, if not at all, English, especially if you are not in Delhi or Mumbai, then prepare for a great language barrier.
Maldives. This place is perfect not only for honeymoon but also for surfing. It was discovered by the Australians in the 70s, crossing the Indian Ocean on a merchant ship towards Male. When one of them was forced to return home, he told his friends about this fabulous place, which served as a real surf boom. Enterprising Australians immediately began to organize trips. From April to October, when the waves will delight even an avid perfectionist, two days on the way will not stop a true surfing fan.
Mauritius. It was opened at the end of the last century. The real thrill is concentrated in the south of the island. What is remarkable, at the same spot at the same time you can meet windsurfers, kitesurfers, and us, ordinary surfers. Therefore, the spots are a bit congested with such a variety. It is also worth noting that Mauritius is included in the segment of luxury resorts, however, like the Maldives, so the option of a hippie vacation or a budget surf trip is unlikely.
Reunion. Small island, former colony of France. The best spots are located on the west coast of the island. It is very attractive for surfers, even though the probability of a shark attack there is incredibly high (this year has already recorded the 19th case with, alas, a sad outcome).
- The so-called "Milk Sea" was discovered in the Indian Ocean - blue water with a shining whitish tint. The reason for this is the bacterium Vibrio Harveyi, which seeks to get into the most favorable habitat for itself - the intestines of other inhabitants of the ocean. To achieve the goal, this creature takes just such a "milky" color.
- The blue-ringed octopus is perhaps the most dangerous inhabitant of the Indian Ocean. The size of a palm, an octopus crumb is capable of killing up to 10 people with its poison at a time. It should be noted right away that in the water it does not pose a danger, but if it is thrown out of its natural habitat, then this creature shows remarkable aggression. The poison paralyzes the muscular and respiratory systems, as a result of which the person begins to suffocate. It is worth noting that the predominantly habitat of this little hitman is, of course, in Australia.
- The Indian Ocean is rich not only in surfing spots, but also unsolvable mysteries. It was in these waters that a merchant ship or ship was found more than once without a single damage, but completely empty. Where people disappeared remains a mystery to this day.
And finally, here's a great shot from Padang Padang surf spot, Bali, Indonesia
INDIAN OCEAN, the third largest ocean on Earth (after the Pacific and Atlantic), part of the World Ocean. Located between Africa in the northwest, Asia in the north, Australia in the east and Antarctica in the south.
Physico-geographical sketch
General information... The border of the Indian Ocean in the west (with the Atlantic Ocean south of Africa) is drawn along the meridian of Cape Agulhas (20 ° east longitude) to the coast of Antarctica (Queen Maud Land), in the east (with the Pacific Ocean south of Australia) - along the eastern border of the Bass Strait to the island of Tasmania, and further along the meridian 146 ° 55 'east longitude to Antarctica, in the northeast (with the Pacific Ocean basin) - between the Andaman Sea and the Strait of Malacca, then along the southwestern shores of Sumatra , Sunda Strait, the southern coast of Java, southern borders the Bali and Sava Seas, the northern border of the Arafura Sea, the southwestern shores of New Guinea and the western border of the Torres Strait. The southern high-latitude part of the Indian Ocean is sometimes referred to as Southern Ocean, which unites the Antarctic sectors of the Atlantic, Indian and Pacific oceans. However, this geographic nomenclature is not universally recognized and, as a rule, the Indian Ocean is considered within its usual boundaries. The Indian Ocean is the only one of the oceans that is located for the most part in the Southern Hemisphere and bounded in the north by a powerful land mass. Unlike other oceans, its mid-ocean ridges form three branches, diverging in different directions from the central part of the ocean.
The area of the Indian Ocean with seas, bays and straits is 76.17 million km 2, the volume of waters is 282.65 million km 3, the average depth is 3711 m (2nd place after the Pacific Ocean); without them - 64.49 million km 2, 255.81 million km 3, 3967 m. The greatest depth in the deep-water Sunda trench is 7729 m at 11 ° 10 'south latitude and 114 ° 57' east longitude. The shelf zone of the ocean (conventionally depths up to 200 m) occupies 6.1% of its area, the continental slope (from 200 to 3000 m) 17.1%, the bed (over 3000 m) 76.8%. See the map.
Seas... The seas, bays and straits in the Indian Ocean are almost three times less than in the Atlantic or Pacific Ocean, they are mainly concentrated in its northern part. Tropical seas: Mediterranean - Red; marginal - Arabian, Lakkadiv, Andaman, Timor, Arafur; Antarctic zone: marginal - Davis, Durville, Cosmonauts, Riiser-Larsen, Commonwealth (see separate articles on the seas). The largest bays: Bengal, Persian, Aden, Oman, Great Australian, Carpentaria, Prudz. Straits: Mozambique, Babel-Mandeb, Bassov, Hormuz, Malacca, Polk, Tenth Degree, Great Channel.
Islands... Unlike other oceans, the islands are few in number. total area about 2 million km 2. The largest islands of mainland origin are Socotra, Sri Lanka, Madagascar, Tasmania, Sumatra, Java, Timor. Volcanic Islands: Reunion, Mauritius, Prince Edward, Crozet, Kerguelen, etc .; coral - Lakkadiv, Maldives, Amirant, Chagos, Nicobar, most of the Andaman, Seychelles; on the volcanic cones rise the coral Comoros, Mascarene, Cocos and other islands.
The shores... The Indian Ocean is distinguished by a relatively small indented coastline, with the exception of the northern and northeastern parts, where most of the seas and the main large bays are located; there are few convenient bays. The shores of Africa in the western part of the ocean are alluvial, weakly dissected, often surrounded coral reefs; in the northwestern part - indigenous. In the north, low, weakly dissected shores with lagoons and sandy bars, in places with mangrove thickets, bordered by coastal lowlands from the land side (Malabar coast, Coromandel coast) prevail; abrasion-accumulative (Konkan coast) and delta shores are also common. In the east, the coasts are indigenous, in Antarctica, covered with glaciers descending to the sea, ending in ice cliffs several tens of meters high.
Bottom relief. Four main elements of geotecture are distinguished in the relief of the bottom of the Indian Ocean: the underwater margins of the continents (including the shelf and the continental slope), transition zones, or zones of island arcs, the ocean floor and mid-ocean ridges. The area of the submarine margins of the continents in the Indian Ocean is 17660 thousand km 2. The submarine edge of Africa is distinguished by a narrow shelf (from 2 to 40 km), its edge is located at a depth of 200-300 m. Only near the southern end of the continent, the shelf expands significantly and in the area of the Agulhas plateau extends up to 250 km from the coast. Large areas of the shelf are occupied by coral structures. The transition from the shelf to the continental slope is expressed by a clear bend in the bottom surface and a rapid increase in its slope up to 10-15 °. The underwater margin of Asia off the coast of the Arabian Peninsula also has a narrow shelf, gradually expanding on the Malabar coast of Hindustan and off the coast of the Bay of Bengal, while the depth on its outer border increases from 100 to 500 m. 4200 m, Sri Lanka island). The shelf and the continental slope in some areas are cut by several narrow and deep canyons, the most pronounced are canyons, which are underwater extensions of the channels of the Ganges rivers (together with the Brahmaputra River, annually carries into the ocean about 1200 million tons of suspended and traction sediment, which formed a layer of sediments over 3500 m thick ) and Ind. Australia's submarine edge has an extensive shelf, especially in the northern and northwestern parts; in the Gulf of Carpentaria and the Arafura Sea up to 900 km wide; the maximum depth is 500 m. The continental slope to the west of Australia is complicated by underwater scarps and separate underwater plateaus (maximum height 3600 m, Aru Islands). On the underwater outskirts of Antarctica, there are everywhere traces of the influence of the ice load of a huge glacier covering the continent. The shelf here belongs to a special glacial type. Its outer boundary almost coincides with the 500 m isobath. The shelf width is from 35 to 250 km. The continental slope is complicated by longitudinal and transverse ridges, individual ridges, valleys and deep trenches. At the foot of the continental slope, an accumulative plume is almost everywhere observed, composed of terrigenous material brought by glaciers. The largest slopes of the bottom are noted in the upper part; with increasing depth, the slope gradually flattens out.
The transition zone at the bottom of the Indian Ocean is distinguished only in the area adjacent to the arc of the Sunda Islands, and represents the south eastern part Indonesian transition area. It includes: the basin of the Andaman Sea, the island arc of the Sunda Islands and deep-sea trenches. The most morphologically expressed in this zone is the deep-water Sunda trench with a slope steepness of 30 ° and more. Relatively small deep-water trenches stand out southeast of Timor Island and east of the Kai Islands, but due to the thick sedimentary layer, their maximum depths are relatively small - 3310 m (Timor Trench) and 3680 m (Kai Trench). The transition zone is extremely seismically active.
The mid-oceanic ridges of the Indian Ocean form three underwater mountain ranges, diverging from an area with coordinates 22 ° south latitude and 68 ° east longitude to the northwest, southwest and southeast. Each of the three branches is divided according to morphological characteristics into two independent ridges: the northwestern - into the Middle Aden ridge and the Arabian-Indian ridge, the southwestern - into the West Indian ridge and the African-Antarctic ridge, the southeastern - into the Central the Indian ridge and the Australian-Antarctic uplift. Thus, the middle ridges divide the Indian Ocean bed into three large sectors. The middle ridges are vast uplifts with a total length of over 16 thousand km, shattered by transform faults into separate blocks, the foothills of which are located at depths of about 5000-3500 m.The relative height of the ridges is 4700-2000 m, width is 500-800 km, the depth of rift valleys is up to 2300 m ...
In each of the three sectors of the Indian Ocean's ocean floor, characteristic landforms are distinguished: hollows, individual ridges, plateaus, mountains, trenches, canyons, etc. -5300 m), Mozambique (4000-6000 m), Madagascar Basin (4500-6400 m), Agulhas (4000-5000 m); underwater ridges: Mascarene ridge, Madagascar, Mozambique; plateau: Agulhas, Mozambican plateau; separate mountains: Equator, Afrikana, Vernadsky, Hall, Bardina, Kurchatova; Amiranta Trench, Mauritius Trench; canyons: Zambezi, Tanganyika and Tagela. In the northeastern sector, there are depressions: Arabian (4000-5000 m), Central (5000-6000 m), Coconut (5000-6000 m), North Australian (5000-5500 m), West Australian basin (5000-6500 m), Naturalist (5000-6000 m) and the South Australian Basin (5000-5500 m); underwater ridges: Maldives ridge, East Indian ridge, West Australian; the Cuvier mountain range; Exmouth Plateau; Mill Upland; separate mountains: Moscow State University, Shcherbakov and Afanasy Nikitin; East Indian trench; canyons: the Indus, Ganges, Sitown and Murray rivers. In the Antarctic sector - the basins: Crozet (4500-5000 m), the African-Antarctic Basin (4000-5000 m) and the Austral-Antarctic Basin (4000-5000 m); plateaus: Kerguelen, Crozet and Amsterdam; separate mountains: Lena and Ob. The shapes and sizes of the basins are different: from rounded with a diameter of about 400 km (Comoros) to elongated giants with a length of 5500 km (Central), the degree of their isolation and bottom topography are different: from flat or gently undulating to hilly and even mountainous.
Geological structure. The peculiarity of the Indian Ocean is that its formation occurred both as a result of the splitting and subsidence of continental massifs, and as a result of the spreading of the bottom and new formation of the oceanic crust within the mid-ocean (spreading) ridges, the system of which was repeatedly rebuilt. The modern mid-ocean ridge system consists of three branches converging at the Rodriguez triple junction. In the northern branch, the Arabian-Indian Ridge continues northwest of the Owen transform fault zone by the rift systems of the Gulf of Aden and the Red Sea and connects with the inland rift systems of East Africa. In the southeastern branch, the Central Indian Ridge and the Austral-Antarctic Rise are separated by the Amsterdam fault zone, with which the plateau of the same name is associated with the volcanic islands of Amsterdam and Saint-Paul. The Arabian-Indian and Central Indian ridges are slow spreading (the spreading rate is 2-2.5 cm / year), they have a well-defined rift valley, and are crossed by numerous transform faults. The wide Australian-Antarctic uplift does not have a pronounced rift valley; the spreading rate on it is higher than on other ridges (3.7-7.6 cm / year). To the south of Australia, the uplift is broken up by the Australian-Antarctic fault zone, where the number of transform faults increases and the spreading axis shifts along the faults in a southerly direction. The ridges of the southwestern branch are narrow, with a deep rift valley, densely intersected by transform faults oriented at an angle to the strike of the ridge. They are characterized by a very low spreading rate (about 1.5 cm / year). The West Indian Ridge is separated from the African-Antarctic Ridge by the Prince Edward, Du Toit, Andrew Bane and Marion Fault System, which displace the axis of the ridge by almost 1000 km to the south. The age of the oceanic crust within the spreading ridges is predominantly Oligocene-Quaternary. The West Indian ridge, which penetrates into the structures of the Central Indian ridge in a narrow wedge, is considered the youngest.
Spreading ridges divide the ocean floor into three sectors - African in the west, Asian-Australian in the northeast, and Antarctic in the south. Within the sectors there are various natures of intraoceanic uplift, represented by "aseismic" ridges, plateaus and islands. Tectonic (block) uplifts have a block structure with different crustal thicknesses; often include continental outliers. Volcanic uplifts are mainly associated with fault zones. Rises are the natural boundaries of deep-water basins. The African sector is characterized by the predominance of fragments of continental structures (including microcontinents), within which the thickness of the earth's crust reaches 17-40 km (the Agulhas and Mozambique plateau, Madagascar ridge with the island of Madagascar, individual blocks of the Mascarene plateau with the Bank of the Seychelles and the Saya de Bank -Malya). Volcanic uplifts and structures include the Comoros submarine ridge, crowned with archipelagos of coral and volcanic islands, the Amiranta ridge, the Reunion islands, Mauritius, Tromelin, and the Farquhar massif. In the western part of the African sector of the Indian Ocean (the western part of the Somali Basin, the northern part of the Mozambique Basin), adjacent to the eastern submarine margin of Africa, the age of the earth's crust is predominantly Late Jurassic-Early Cretaceous; in the central part of the sector (Mascarenskaya and Madagascar basins) - Late Cretaceous; in the northeastern part of the sector (eastern part of the Somali Basin) - Paleocene-Eocene. In the Somali and Mascarene basins, ancient spreading axes and intersecting transform faults were identified.
The northwestern (Asian) part of the Asian-Australian sector is characterized by meridional "aseismic" ridges of a block structure with an increased thickness of the oceanic crust, the formation of which is associated with a system of ancient transform faults. These include the Maldives ridge, crowned with archipelagos of coral islands - Laccadives, Maldives and Chagos; the so-called 79 ° ridge, Lanka ridge with Mount Athanasius Nikitin, East Indian (the so-called 90 ° ridge), Investigeytor, etc. Powerful (8-10 km) sediments of the Indus, Ganges and Brahmaputra rivers in the northern Indian Ocean partially overlap the in this direction, ridges, as well as structures of the transition zone of the Indian Ocean - the southeastern edge of Asia. The Murri Ridge in the northern part of the Arabian Basin, bordering the Oman Basin in the south, is an extension of folded land structures; enters the Owen Fault Zone. To the south of the equator, a sublatitudinal zone of intraplate deformations with a width of up to 1000 km is revealed, which is characterized by high seismicity. It stretches in the Central and Coconut Basins from the Maldives ridge to the Sunda Trench. The Arabian Basin is underlain by the crust of the Paleocene-Eocene age, the Central Basin by the crust of the Late Cretaceous - Eocene age; the crust is the youngest in the southern part of the basins. In the Coconut Basin, the age of the crust varies from Late Cretaceous in the south to Eocene in the north; in its northwestern part, an ancient spreading axis is established, dividing the Indian and Australian lithospheric plates until the middle of the Eocene. The Coconut Ramp is a latitudinal uplift with numerous seamounts and islands (including the Cocos Islands) towering over it, and the Ru uplift, adjacent to the Sunda Trench, separate the southeastern (Australian) part of the Asian-Australian sector. The Western Australian Basin (Wharton) in the central part of the Asian-Australian sector of the Indian Ocean is underlain in the northwest by the Late Cretaceous crust, in the east by the Late Jurassic. Submerged continental blocks (the marginal plateaus of Exmouth, Cuvier, Zenith, Naturalista) divide the eastern part of the basin into separate depressions - Cuvier (north of the Cuvier plateau), Perth (north of the Naturalista plateau). The crust of the North Australian Basin (Argo) is the oldest in the south (Late Jurassic); becomes younger in a northerly direction (before the Early Cretaceous). The age of the crust of the South Australian Basin of the Late Cretaceous is Eocene. The Broken Plateau is an intraoceanic uplift with an increased (from 12 to 20 km, according to various sources) crustal thickness.
The Antarctic sector of the Indian Ocean contains mainly volcanic intraoceanic uplifts with increased crustal thickness: the Kerguelen Plateau, Crozet (Del Caño) and Conrad. Within the largest Kerguelen plateau, presumably laid on an ancient transform fault, the thickness of the earth's crust (according to some data, the Early Cretaceous age) reaches 23 km. Towering over the plateau, the Kerguelen Islands are a multiphase volcanoplutonic structure (composed of Neogene alkaline basalts and syenites). On Heard Island - Neogene-Quaternary alkaline volcanics. In the western part of the sector are the Konrad plateau with the volcanic mountains Ob and Lena, as well as the Crozet plateau with a group of volcanic islands Marion, Prince Edward, Crozet, composed of Quaternary basalts and intrusive massifs of syenites and monzonites. The age of the earth's crust within the African-Antarctic, Australian-Antarctic basins and the Crozet basin is Late Cretaceous - Eocene.
The Indian Ocean is characterized by the predominance of passive margins (continental margins of Africa, the Arabian and Indian peninsulas, Australia, Antarctica). An active margin is observed in the northeastern part of the ocean (the Sunda Indian Ocean - Southeast Asia transition zone), where the ocean lithosphere is subducted (underthrust) under the Sunda island arc. A limited in extent subduction zone - Makranskaya - was found in the northwestern part of the Indian Ocean. Along the Agulhas plateau, the Indian Ocean borders the African continent along a transform fault.
The formation of the Indian Ocean began in the middle of the Mesozoic during the splitting of the Gondwana part (see Gondwana) of the Pathea supercontinent, which was preceded by continental rifting during the Late Triassic - Early Cretaceous. The formation of the first sections of oceanic crust as a result of the spreading of continental plates began in the Late Jurassic in the Somali (about 155 million years ago) and North Australian (151 million years ago) basins. In the Late Cretaceous, the expansion of the bottom and new formation of the oceanic crust was experienced by the northern part of the Mozambique Basin (140-127 million years ago). The separation of Australia from Hindustan and Antarctica, accompanied by the opening of basins with oceanic crust, began in the Early Cretaceous (about 134 million years ago and about 125 million years ago, respectively). Thus, in the Early Cretaceous (about 120 million years ago), narrow oceanic basins arose, cutting into the supercontinent and dividing it into separate blocks. In the middle of the Cretaceous period (about 100 million years ago), the ocean floor began to expand rapidly between Hindustan and Antarctica, which led to the drift of Hindustan in a northerly direction. In the time interval 120-85 million years ago, the spreading axes that existed north and west of Australia, off the coast of Antarctica and in the Mozambique Strait, died out. In the Late Cretaceous (90-85 million years ago), a split began between Hindustan with the Mascarene-Seychelles block and Madagascar, which was accompanied by bottom spreading in the Mascarene, Madagascar and Crozet basins, as well as the formation of the Australo-Antarctic uplift. At the Cretaceous-Paleogene boundary, Hindustan separated from the Mascarene-Seychelles block; the Arabian-Indian spreading ridge arose; the spreading axes died out in the Mascarenskaya and Madagascar basins. Mid Eocene Indian lithospheric plate merged with the Australian; the still developing system of mid-oceanic ridges was formed. The Indian Ocean acquired a similar appearance to its present-day appearance at the beginning - the middle of the Miocene. In the middle of the Miocene (about 15 million years ago), with the split of the Arabian and African plates, a new formation of the oceanic crust began in the Gulf of Aden and the Red Sea.
Modern tectonic movements in the Indian Ocean are noted in the mid-ocean ridges (associated with shallow earthquakes), as well as in individual transform faults. The area of intense seismicity is the Sunda island arc, where deep-focus earthquakes are caused by the presence of a seismic focal zone plunging in a northeasterly direction. Earthquakes on the northeastern edge of the Indian Ocean may cause a tsunami.
Bottom sediments. The rate of sedimentation in the Indian Ocean is generally lower than in the Atlantic and Pacific Oceans. The thickness of the strata of modern bottom sediments varies from discontinuous distribution on mid-ocean ridges to several hundred meters in deep-water basins and 5000-8000 m at the foot of the continental slopes. The most widespread calcareous (mainly foraminiferal-coccolithic) oozes, covering over 50% of the ocean floor area (on continental slopes, ridges and the bottom of hollows at depths of up to 4700 m) in warm oceanic regions from 20 ° north latitude to 40 ° south latitude from high biological productivity of waters. Polygenic sediments - red deep-sea oceanic clays - occupy 25% of the seabed at depths of more than 4700 m in the eastern and southeastern parts of the ocean from 10 ° north latitude to 40 ° south latitude and on bottom areas remote from islands and continents; in the tropics, red clays are interspersed with siliceous radiolarian oozes that cover the bottom of the deep-water basins of the equatorial belt. In deep-sea sediments, ferromanganese nodules are present in the form of inclusions. Siliceous, mainly diatomaceous, silts occupy about 20% of the Indian Ocean floor; extended to great depths south of latitude 50 ° S. The accumulation of terrigenous sediments (pebbles, gravel, sands, silts, clays) occurs mainly along the coasts of the continents and within their submarine margins in the areas of river and iceberg runoff, significant wind removal of material. Sediments covering the African shelf are mainly of shell and coral origin; phosphorite nodules are widely developed in the southern part. Along the northwestern periphery of the Indian Ocean, as well as in the Andaman Basin and in the Sunda Trench, bottom sediments are mainly represented by sediments of turbid flows - turbidites with the participation of products of volcanic activity, underwater avalanches, landslides, etc. Sediments of coral reefs are widespread in the western parts of the Indian Ocean from 20 ° south latitude to 15 ° north latitude, and in the Red Sea - up to 30 ° north latitude. Outcrops of metal-bearing brines with temperatures up to 70 ° C and salinity up to 300 ‰ were found in the rift valley of the Red Sea. Metalliferous sediments formed from these brines contain a high content of non-ferrous and rare metals. Outcrops of bedrocks (basalts, serpentinites, peridotites) are noted on the continental slopes, seamounts, and mid-ocean ridges. Bottom sediments around Antarctica are classified as a special type of iceberg sediments. They are characterized by the predominance of a variety of clastic material, ranging from large boulders to silts and thin silts.
Climate... Unlike the Atlantic and Pacific Oceans, which have a meridional strike from the shores of Antarctica to the Arctic Circle and communicate with the Arctic Ocean, the Indian Ocean in the northern tropical region is bordered by a land mass, which largely determines the features of its climate. The uneven heating of land and ocean leads to seasonal changes in vast minima and maxima of atmospheric pressure and to seasonal displacements of the tropical atmospheric front, which in the winter of the Northern Hemisphere retreats southward to almost 10 ° S latitude, and in summer is located in the foothill regions of southern Asia. As a result, the northern Indian Ocean is dominated by a monsoon climate, which is primarily characterized by a change in wind direction throughout the year. The winter monsoon with relatively weak (3-4 m / s) and stable northeast winds operates from November to March. During this period, to the north of 10 ° S latitude, it was not uncommon to calm down. The summer monsoon with south-westerly winds occurs from May to September. In the northern tropical region and in the equatorial zone of the ocean, the average wind speed reaches 8-9 m / s, often reaching a storm force. In April and October, a restructuring of the baric field usually occurs, and during these months the wind situation is unstable. Against the background of the prevailing monsoon atmospheric circulation over the northern part of the Indian Ocean, individual manifestations of cyclonic activity are possible. During the winter monsoon, there are known cases of the development of cyclones over the Arabian Sea, during the summer monsoon - over the waters of the Arabian Sea and the Bay of Bengal. Strong cyclones in these areas are sometimes formed during monsoon periods.
A stable region is located at about 30 ° S latitude in the central Indian Ocean high pressure, the so-called South Indian maximum. This stationary anticyclone, an integral part of the high-pressure southern subtropical region, persists throughout the year. The pressure in its center varies from 1024 hPa in July to 1020 hPa in January. Under the influence of this anticyclone, stable southeastern trade winds blow in the latitudinal zone between 10 and 30 ° S latitude throughout the year.
South of 40 ° S latitude, atmospheric pressure in all seasons decreases uniformly from 1018-1016 hPa at the southern periphery of the South Indian Maximum to 988 hPa at 60 ° S. Under the influence of the meridional pressure gradient in the lower atmosphere, a stable western air transport is maintained. The highest average wind speed (up to 15 m / s) is observed in the middle of winter in the Southern Hemisphere. For the higher southern latitudes of the Indian Ocean, storm conditions are typical throughout almost the entire year, in which winds with speeds of more than 15 m / s, causing waves over 5 m, have a recurrence rate of 30%. South of 60 ° S latitude along the coast of Antarctica, easterly winds and two to three cyclones are usually observed per year, most often in July - August.
In July, the highest air temperature values in the near-surface layer of the atmosphere are noted in the top of the Persian Gulf (up to 34 ° C), the lowest - off the coast of Antarctica (-20 ° C), over the Arabian Sea and the Bay of Bengal, on average 26-28 ° C. Over the Indian Ocean, air temperature almost everywhere changes in accordance with geographical latitude.
In the southern part of the Indian Ocean, it gradually decreases from north to south by about 1 ° С for every 150 km. In January, the highest air temperature values (26-28 ° С) are noted in the equatorial zone, near the northern coasts of the Arabian Sea and the Bay of Bengal - about 20 ° С. In the southern part of the ocean, the temperature decreases uniformly from 26 ° С in the Southern Tropics to 0 ° С and slightly lower at the latitude of the Antarctic Circle. The amplitude of annual fluctuations in air temperature over most of the Indian Ocean water area is on average less than 10 ° С and only near the coast of Antarctica increases to 16 ° С.
The largest amount of precipitation per year falls in the Bay of Bengal (over 5500 mm) and off the eastern shores of Madagascar (over 3500 mm). The northern coastal part of the Arabian Sea receives the least amount of precipitation (100-200 mm per year).
The northeastern regions of the Indian Ocean are located in seismically active areas. The east coast of Africa and the island of Madagascar, the shores of the Arabian Peninsula and the Indian subcontinent, almost all island archipelagos of volcanic origin, the western coasts of Australia, especially the arc of the Sunda Islands, in the past have been repeatedly exposed to tsunami waves of varying strength, up to catastrophic ones. In 1883, after the explosion of the Krakatau volcano in the Jakarta region, a tsunami with a wave height of over 30 m was recorded; in 2004, a tsunami caused by an earthquake in the region of Sumatra had catastrophic consequences.
Hydrological regime. Seasonality in changes in hydrological characteristics (primarily temperature and currents) is most clearly manifested in the northern part of the ocean. The summer hydrological season here corresponds to the time of the southwestern monsoon (May - September), the winter - to the northeastern monsoon (November - March). The peculiarity of the seasonal variability of the hydrological regime is that the restructuring of the hydrological fields is somewhat delayed relative to the meteorological fields.
Water temperature... In winter in the Northern Hemisphere, the highest water temperatures in the surface layer are observed in the equatorial zone - from 27 ° С off the coast of Africa to 29 ° С and more east of the Maldives. In the northern regions of the Arabian Sea and the Bay of Bengal, the water temperature is about 25 ° C. In the southern part of the Indian Ocean, a zonal distribution of temperature is characteristic everywhere, which gradually decreases from 27-28 ° С at 20 ° south latitude to negative values at the edge of the drifting ice located at about 65-67 ° south latitude. In the summer season, the highest values of water temperature in the surface layer are noted in the Persian Gulf (up to 34 ° С), in the northwest of the Arabian Sea (up to 30 ° С), in the eastern part of the equatorial zone (up to 29 ° С). In the coastal regions of the Somali and Arabian peninsulas, abnormally low values (sometimes less than 20 ° C) are observed at this time of the year, which is the result of the rise to the surface of cooled deep waters in the Somali current system. In the southern part of the Indian Ocean, the distribution of water temperature throughout the year retains a zonal character, with the difference that its negative values in the winter of the Southern Hemisphere are found much further north, already at about 58-60 ° S latitude. The amplitude of annual fluctuations in water temperature in the surface layer is small and averages 2-5 ° С, only in the region of the Somali coast and in the Gulf of Oman of the Arabian Sea it exceeds 7 ° С. The water temperature rapidly decreases vertically: at a depth of 250 m, it almost everywhere drops below 15 ° С, deeper than 1000 m - below 5 ° С. At a depth of 2000 m, temperatures above 3 ° C are noted only in the northern part of the Arabian Sea, in the central regions - about 2.5 ° C, in the southern part it decreases from 2 ° C at 50 ° South latitude to 0 ° C off the coast of Antarctica. Temperatures in the deepest (over 5000 m) basins range from 1.25 ° C to 0 ° C.
Salinity surface waters The Indian Ocean is determined by the balance between the amount of evaporation and the total amount of precipitation and river flow for each area. The absolute maximum salinity (over 40 ‰) is observed in the Red Sea and the Persian Gulf, in the Arabian Sea everywhere, except for a small area in the southeastern part, salinity is higher than 35.5 ‰, in the 20-40 ° south latitude - more than 35 ‰ ... The area of low salinity is located in the Bay of Bengal and in the area adjacent to the arc of the Sunda Islands, where there is a large fresh river runoff and the greatest amount of precipitation. In the northern part of the Bay of Bengal, salinity is 30-31 ‰ in February, and 20 ‰ in August. An extensive tongue of waters with salinity of up to 34.5 ‰ at 10 ° S latitude extends from Java to 75 ° E. In Antarctic waters, salinity is everywhere below the average oceanic value: from 33.5 ‰ in February to 34.0 ‰ in August, its changes are determined by slight salinization during the formation of sea ice and the corresponding desalination during the period of ice melting. Seasonal changes in salinity are noticeable only in the upper, 250-meter, layer. With increasing depth, not only seasonal fluctuations fade out, but also the spatial variability of salinity, deeper than 1000 m, it fluctuates within 35-34.5 ‰.
Density... The highest water density in the Indian Ocean is noted in the Suez and Persian Gulfs (up to 1030 kg / m 3) and in cold Antarctic waters (1027 kg / m 3), average - in the warmest and salt waters in the northwest (1024-1024.5 kg / m 3), the smallest - near the most freshened waters in the northeastern part of the ocean and in the Bay of Bengal (1018-1022 kg / m 3). With depth, mainly due to a decrease in water temperature, its density increases, sharply increasing in the so-called jump layer, which is most pronounced in the equatorial zone of the ocean.
Ice regime. The severity of the climate in the southern Indian Ocean is such that the process of sea ice formation (at air temperatures below -7 ° C) can occur almost all year round. The greatest development of the ice cover reaches in September - October, when the width of the belt of drifting ice reaches 550 km, the smallest - in January - February. The ice cover is characterized by high seasonal variability, its formation occurs very quickly. The ice edge moves northward at a speed of 5-7 km / day, just as quickly (up to 9 km / day) retreats to the south during the melting period. Fast ice is established annually, reaches an average width of 25-40 km and melts almost completely by February. Drifting ice off the coast of the mainland moves under the influence of katabatic winds in the general direction to the west and northwest. Near the northern edge, ice drifts eastward. Characteristic feature The Antarctic ice sheet is a large number of icebergs breaking off from the outlet and ice shelves of Antarctica. Table-like icebergs are especially large, which can reach a gigantic length of several tens of meters, rising 40-50 m above the water. Their number decreases rapidly with distance from the coast of the mainland. The life span of large icebergs is 6 years on average.
Currents... The circulation of surface water in the northern Indian Ocean is formed by monsoon winds and therefore varies significantly from summer to winter. In February, from 8 ° N near the Nicobar Islands to 2 ° N latitude off the coast of Africa, there is a surface winter Monsoon Current with velocities of 50-80 cm / s; with a rod running along approximately 18 ° S latitude, the South Passat Current extends in the same direction, which has average speed on the surface about 30 cm / s. Connecting off the coast of Africa, the waters of these two streams give rise to an inter-trade countercurrent, which carries its waters to the east with velocities in the core of about 25 cm / s. Along the North African coast, with a general direction to the south, the waters of the Somali current move, partially turning into the Inter-trade countercurrent, and to the south, the Mozambique and Cape Igolny currents, going south at speeds of about 50 cm / s. Part of the South Tradewind Current off the east coast of Madagascar turns south along it (Madagascar Current). South of 40 ° S latitude, the entire ocean area is crossed from west to east by the flow of the longest and most powerful current in the World Ocean of the Western Winds (Antarctic Circumpolar Current). The velocities in its rods reach 50 cm / s, and the flow rate is about 150 million m 3 / s. At 100-110 ° E longitude, a stream branches off from it, heading north and giving rise to the West Australian Current. In August, the Somali current follows the general direction to the northeast and at a speed of up to 150 cm / s draws water into the northern part of the Arabian Sea, from where the Monsoon current, bending around the western and southern shores of the Indian subcontinent and the island of Sri Lanka, carries water to the coast of the island Sumatra, turns to the south and merges with the waters of the South Tradewind Current. Thus, in the northern part of the Indian Ocean, an extensive clockwise circulation is created, consisting of the Monsoon, South Passat and Somali currents. In the southern part of the ocean, the pattern of currents changes little from February to August. Off the coast of Antarctica, in a narrow coastal strip, a current caused by katabatic winds and directed from east to west is observed all year round.
Water masses... In the vertical structure of the Indian Ocean water masses, the hydrological characteristics and depth of occurrence differ in surface, intermediate, deep and bottom waters. Surface waters are distributed in a relatively thin surface layer and occupy the upper 200-300 m on average. From north to south, water masses are distinguished in this layer: Persian and Arabian in the Arabian Sea, Bengal and South Bengal in the Bay of Bengal; Further, south of the equator, - Equatorial, Tropical, Subtropical, Subantarctic and Antarctic. As the depth increases, the differences between neighboring water masses decrease and their number decreases accordingly. So, in intermediate waters, the lower boundary of which reaches 2000 m in temperate and low latitudes and up to 1000 m in high latitudes, there are Persian and Red Sea in the Arabian Sea, Bengal in the Bay of Bengal, Subantarctic and Antarctic intermediate water masses. Deep waters are represented by the North Indian, Atlantic (in the western part of the ocean), Central Indian (in the eastern part) and Circumpolar Antarctic water masses. Bottom waters everywhere, except the Bay of Bengal, are represented by one Antarctic bottom water mass, which fills all deep-water basins. The upper boundary of the bottom water is located on average at the horizon of 2500 m off the coast of Antarctica, where it forms, up to 4000 m in the central regions of the ocean and rises to almost 3000 m north of the equator.
Tides and excitement... The most widespread on the shores of the Indian Ocean are semidiurnal and irregular semidiurnal tides. Semi-diurnal tides are observed on the African coast south of the equator, in the Red Sea, off the northwestern shores of the Persian Gulf, in the Bay of Bengal, off the northwestern coast of Australia. Irregular semi-daily tides - off the Somali Peninsula, in the Gulf of Aden, off the coast of the Arabian Sea, in the Persian Gulf, off the southwestern shores of the Sunda Island Arc. Diurnal and irregular diurnal tides are noted off the western and southern coasts of Australia. The highest tides are off the northwestern coast of Australia (up to 11.4 m), in the mouth zone of the Indus (8.4 m), in the mouth zone of the Ganges (5.9 m), off the coast of the Mozambique Strait (5.2 m) ; in the open ocean, the magnitude of tides varies from 0.4 m in the Maldives to 2.0 m in the southeastern part of the Indian Ocean. The excitement reaches greatest strength in temperate latitudes in the zone of action of westerly winds, where the frequency of waves over 6 m in height is 17% per year. Waves with a height of 15 m and a length of 250 m were recorded near Kerguelen Island, 11 m and 400 m, respectively, off the coast of Australia.
Flora and fauna... The main part of the Indian Ocean is located within the tropical and southern temperate zones. The absence of a northern high-latitude region in the Indian Ocean and the effect of monsoons lead to two multidirectional processes that determine the characteristics of the local flora and fauna. The first factor complicates deep-sea convection, which negatively affects the renewal of deep waters in the northern part of the ocean and an increase in oxygen deficiency in them, which is especially pronounced in the Red Sea intermediate water mass, which leads to a depletion of the species composition and reduces the total biomass of zooplankton in the intermediate layers. When oxygen-poor waters in the Arabian Sea emerge on the shelf, local deaths occur (the death of hundreds of thousands of tons of fish). At the same time, the second factor (monsoons) creates favorable conditions for high biological productivity in coastal areas. The summer monsoon drives water along the Somali and Arabian coasts, causing a powerful upwelling that brings to the surface waters rich in nutrient salts. The winter monsoon, albeit to a lesser extent, leads to seasonal upwelling with similar consequences off the western coast of the Indian subcontinent.
The coastal zone of the ocean is characterized by the greatest species diversity. The shallow waters of the tropical belt are characterized by numerous 6- and 8-rayed madrepore corals, hydrocorals, which, together with red algae, are capable of creating underwater reefs and atolls. Among the powerful coral buildings, the richest fauna of various invertebrates (sponges, worms, crabs, mollusks, sea urchins, ophiuras and sea stars), small but brightly colored coral reef fish. Most of the coasts are occupied by mangroves. At the same time, the fauna and flora of beaches and rocks drying out at low tide are quantitatively depleted due to the oppressive effect of sunlight. In the temperate zone, life on such coastal areas is much richer; here dense thickets of red and brown algae (kelp, fucus, macrocystis) develop, a variety of invertebrates are abundant. According to L.A. Zenkevich (1965), over 99% of all species of bottom and bottom animals living in the ocean live in the littoral and sublittoral zones.
The open spaces of the Indian Ocean, especially the surface layer, are also characterized by rich flora. The food chain in the ocean begins with microscopic unicellular plant organisms - phytoplankton, which inhabits mainly the uppermost (approximately 100-meter) layer of ocean waters. Among them, several species of peridinium and diatom algae prevail, and in the Arabian Sea - cyanobacteria (blue-green algae), often causing the so-called water bloom during mass development. There are three areas of the highest phytoplankton production in the northern Indian Ocean: the Arabian Sea, the Bay of Bengal and the Andaman Sea. The largest production is observed off the coast of the Arabian Peninsula, where the number of phytoplankton sometimes exceeds 1 million cells / l (cells per liter). Its high concentrations are also observed in the subantarctic and antarctic zones, where during the period of spring flowering there are up to 300,000 cells / l. The smallest production of phytoplankton (less than 100 cells / l) is observed in the central part of the ocean between the parallels 18 and 38 ° south latitude.
Zooplankton inhabits almost the entire oceanic waters, but its number rapidly decreases with increasing depth and decreases by 2-3 orders of magnitude towards the bottom layers. Phytoplankton serve as food for most of the zooplankton, especially those living in the upper layers; therefore, the patterns of the spatial distribution of phyto- and zooplankton are largely similar. The highest indicators of zooplankton biomass (from 100 to 200 mg / m3) are observed in the Arabian and Andaman Seas, Bengal, Aden and Persian Gulfs. The main biomass of ocean animals is made up of copepod crustaceans (more than 100 species), slightly less pteropods, jellyfish, siphonophores and other invertebrates. Of unicellular organisms, radiolarians are typical. The Antarctic region of the Indian Ocean is characterized by a huge number of euphausian crustaceans of several species, collectively called "krill". Euphausiids provide the main food base for the largest animals on Earth - baleen whales. In addition, fish, seals, cephalopods, penguins and other bird species feed on krill.
Organisms that move freely in the marine environment (nekton) are represented in the Indian Ocean mainly by fish, cephalopods, and cetaceans. Of the cephalopods in the Indian Ocean, cuttlefish, numerous squids and octopuses are common. Of the fish, several species of flying fish are most abundant, luminous anchovies (coryphans), sardinella, sardine, mackerel fishes, notothenia, sea bass, several types of tuna, blue marlin, grenadier, sharks, rays. The warm waters are home to sea turtles and poisonous sea snakes. The fauna of aquatic mammals is represented by various cetaceans. Of the baleen whales, the following are widespread: blue, sei whale, fin whale, humpback whale, Australian (Cape) Chinese. Toothed whales are represented by sperm whales, several species of dolphins (including killer whales). In the coastal waters of the southern part of the ocean, pinnipeds are widespread: the Weddell seal, the crabeater seal, the Australian, Tasmanian, Kerguelen and South African seals, the Australian sea lion, the leopard seal, and others. , cormorants, gannets, skuas, terns, gulls. South of 35 ° S latitude, on the coasts of South Africa, Antarctica and the islands, there are numerous colonies of several species of penguins.
In 1938, a unique biological phenomenon was discovered in the Indian Ocean - the live cross-finned fish Latimeria chalumnae, which was considered extinct tens of millions of years ago. The "fossil" coelacanth lives at a depth of over 200 m in two places - near the Comoros and in the waters of the Indonesian archipelago.
Research history
The northern coastal areas, especially the Red Sea and deeply cut bays, began to be used by man for navigation and fishing already in the era of ancient civilizations, several thousand years before our era. For 600 BC, Phoenician seafarers in the service of the Egyptian Pharaoh Necho II sailed around Africa by sea. In 325-324 BC, a colleague of Alexander the Great Nearchus, commanding a fleet, sailed from India to Mesopotamia and compiled the first descriptions of the shores from the mouth of the Indus River to the top of the Persian Gulf. In the 8-9 centuries, the Arabian Sea was intensively explored by Arab navigators, who created the first sailing directions and navigational guides for this area. In the first half of the 15th century, Chinese navigators under the leadership of Admiral Zheng He made a number of voyages along the Asian coast to the west, reaching the shores of Africa. In 1497-99 Portuguese Gama (Vasco da Gama) paved for Europeans sea route to India and to the countries of Southeast Asia. A few years later, the Portuguese discovered the island of Madagascar, Amirante, Comoros, Mascarene and Seychelles. Following the Portuguese, the Dutch, French, Spanish and British entered the Indian Ocean. The name "Indian Ocean" first appeared on European maps in 1555. In 1772-75 J. Cook penetrated the Indian Ocean to 71 ° south latitude and made the first deep-sea measurements. The beginning of oceanographic research of the Indian Ocean was laid by systematic measurements of water temperature during circumnavigation Russian ships"Rurik" (1815-18) and "Enterprise" (1823-26). In 1831-36, an English expedition took place on the ship "Beagle", on which Charles Darwin carried out geological and biological work. Integrated oceanographic measurements in the Indian Ocean were carried out during the British expedition on board the Challenger in 1873-74. Oceanographic work in the northern part of the Indian Ocean was carried out in 1886 by S.O. Makarov on the Vityaz ship. In the first half of the 20th century, oceanographic observations began to be carried out regularly, and by the 1950s, they were carried out at almost 1,500 deep-sea oceanographic stations. In 1935, P. G. Schott's monograph "Geography of the Indian and Pacific Oceans" was published, the first major publication summarizing the results of all previous studies in this region. In 1959, the Russian oceanographer A. M. Muromtsev published a fundamental work - "The main features of the hydrology of the Indian Ocean." In 1960-65, the Scientific Committee on Oceanography of UNESCO conducted the International Indian Ocean Expedition (IIOE), the largest previously operated in the Indian Ocean. Scientists from more than 20 countries of the world (USSR, Australia, Great Britain, India, Indonesia, Pakistan, Portugal, USA, France, Germany, Japan, etc.) took part in the MIOE program. In the course of MIOE, large geographical discoveries: discovered underwater West Indian and East Indian ridges, tectonic fault zones - Owen, Mozambique, Tasman, Dayamantina and others, seamounts - Ob, Lena, Afanasy Nikitina, Bardina, Zenith, Equator, etc., deep-sea trenches - Ob , Chagos, Vima, Vityaz, etc. In the history of the study of the Indian Ocean, the results of research carried out in 1959-77 by the research vessel Vityaz (10 voyages) and dozens of other Soviet expeditions aboard the ships of the Hydrometeorological Service and the State Fisheries Committee stand out. Since the early 1980s, ocean research has been carried out in the framework of 20 international projects. Especially intensified research of the Indian Ocean during the period of the International World Ocean Circulation Experiment (WOCE). Since its successful completion in the late 1990s, the amount of modern oceanographic information on the Indian Ocean has doubled.
Economic use
The coastal area of the Indian Ocean is distinguished by an exceptionally high population density. More than 35 states are located on the coasts and islands of the ocean, in which about 2.5 billion people live (over 30% of the world's population). The bulk of the coastal population is concentrated in South Asia (more than 10 cities with a population of over 1 million). In most of the countries of the region, there are acute problems of finding living space, creating jobs, providing food, clothing and housing, and medical care.
The use of the Indian Ocean, like other seas and oceans, is carried out in several main areas: transport, fishing, mining of mineral resources, and recreation.
Transport... The role of the Indian Ocean in maritime transport increased significantly with the creation of the Suez Canal (1869), which opened a short sea route of communication with the states washed by the waters of the Atlantic Ocean. The Indian Ocean is an area of transit and export of all kinds of raw materials, in which almost all major seaports are of international importance. In the northeastern part of the ocean (in the Malacca and Sunda straits) there are routes of ships going to the Pacific Ocean and back. The main export to the USA, Japan and Western Europe is crude oil from the Persian Gulf. In addition, agricultural products are exported - natural rubber, cotton, coffee, tea, tobacco, fruits, nuts, rice, wool; wood; mineral raw materials - coal, iron ore, nickel, manganese, antimony, bauxite, etc .; machinery, equipment, tools and metal products, chemical and pharmaceutical products, textiles, processed gems and jewelry. The Indian Ocean accounts for about 10% of the world's shipping traffic; at the end of the 20th century, about 0.5 billion tons of cargo per year were transported across its waters (according to the IOC). According to these indicators, it ranks third after the Atlantic and Pacific Oceans, yielding to them in terms of the intensity of shipping and the total volume of cargo transportation, but surpassing all other maritime transport communications in terms of the volume of oil shipments. The main transport routes passing through the Indian Ocean are directed to the Suez Canal, the Strait of Malacca, the southern extremities of Africa and Australia, and along the northern coast. The most intensive shipping is in the northern regions, although it is limited by stormy conditions during the summer monsoon, less intensive in the central and southern regions. The growth in oil production in the Gulf countries, Australia, Indonesia and other places contributed to the construction and modernization of oil ports and the emergence of giant tankers in the Indian Ocean.
The most developed transport routes for the transportation of oil, gas and oil products: Persian Gulf - Red Sea - Suez Canal - Atlantic Ocean; Persian Gulf - Strait of Malacca - Pacific Ocean; The Persian Gulf - the southern tip of Africa - the Atlantic Ocean (especially before the reconstruction of the Suez Canal, 1981); Persian Gulf - coast of Australia (port of Fremantle). Mineral and agricultural raw materials, textiles, precious stones, jewelry, equipment, computer equipment are transported from India, Indonesia, Thailand. Coal, gold, aluminum, alumina, iron ore, diamonds, uranium ores and concentrates, manganese, lead, zinc are transported from Australia; wool, wheat, meat products, as well as internal combustion engines, passenger cars, electrical products, river boats, glass products, rolled steel, etc. Industrial goods, automobiles, electronic equipment, etc. prevail in the oncoming traffic. Passenger transportation takes an important place in the transport use of the Indian Ocean.
Fishing... Compared to other oceans, the Indian Ocean has a relatively low biological productivity, the catch of fish and other seafood is 5-7% of the total world catch. Fishing and non-fish fishing is concentrated mainly in the northern part of the ocean, and in the west it is twice as large as the catch in the eastern part. The largest volumes of bioproducts are extracted in the Arabian Sea off the western coast of India and off the coast of Pakistan. In the Persian and Bengal Gulfs, shrimp are harvested, off the east coast of Africa and on tropical islands - crayfish. In the open areas of the ocean in the tropical zone, tuna fishing is widely developed, which is carried out by countries with a well-developed fishing fleet. In the Antarctic region, nototheniaceae, ice fish and krill are caught.
Mineral resources... The deposits of oil and natural combustible gas or oil and gas show have been discovered practically over the entire shelf area of the Indian Ocean. Of the greatest industrial importance are actively developed oil and gas fields in the gulfs: Persian (Persian Gulf oil and gas basin), Suez (oil and gas basin of the Gulf of Suez), Cambay (Cambay oil and gas basin), Bengal (Bengal oil and gas basin); off the northern coast of Sumatra Island (North Sumatra oil and gas basin), in the Timor Sea, off the northwestern coast of Australia (Carnarvon oil and gas basin), in the Strait of Bass (Gippsland oil and gas basin). Gas deposits have been explored in the Andaman Sea, oil and gas regions - in the Red Sea, the Gulf of Aden, along the coast of Africa. Coastal-marine placers of heavy sands are developed off the coast of Mozambique, along the southwestern and northeastern coasts of India, off the northeastern shores of Sri Lanka, along the southwestern coast of Australia (mining of ilmenite, rutile, monazite and zircon); in the coastal regions of Indonesia, Malaysia, Thailand (mining of cassiterite). Industrial accumulations of phosphorites have been found on the shelves of the Indian Ocean. On the ocean floor, large fields of ferromanganese nodules are established - a promising source of Mn, Ni, Cu, Co. In the Red Sea, the revealed metal-bearing brines and sediments are potential sources of extraction of iron, manganese, copper, zinc, nickel, etc .; there are deposits of rock salt. In the coastal zone of the Indian Ocean, sand is mined for construction and the production of glass, gravel, limestone.
Recreational resources... From the 2nd half of the 20th century great importance for the economies of coastal countries has the use of recreational resources of the ocean. Old resorts are developing and new ones are being built on the coast of the continents and on numerous tropical islands in the ocean. The most visited resorts are in Thailand (Phuket island, etc.) - over 13 million people a year (together with the coast and islands of the Gulf of Thailand), in Egypt [Hurghada, Sharm el-Sheikh (Sharm el-Sheikh), etc. ] - over 7 million people, in Indonesia (Bali, Bintan, Kalimantan, Sumatra, Java, etc.) - over 5 million people, in India (Goa, etc.), Jordan (Aqaba), Israel (Eilat) , in the Maldives, in Sri Lanka, in the Seychelles, on the islands of Mauritius, Madagascar, in South Africa, etc.
Sharm El Sheikh. Hotel "Concord".
Port cities... Oil-loading specialized ports are located on the shores of the Indian Ocean: Ras Tanura (Saudi Arabia), Khark (Iran), Esh-Shuaiba (Kuwait). The largest ports of the Indian Ocean: Port Elizabeth, Durban (South Africa), Mombasa (Kenya), Dar es Salaam (Tanzania), Mogadishu (Somalia), Aden (Yemen), Kuwait (Kuwait), Karachi (Pakistan), Mumbai, Chennai, Kolkata, Kandla (India), Chittagong (Bangladesh), Colombo (Sri Lanka), Yangon (Myanmar), Fremantle, Adelaide and Melbourne (Australia).
Lit .: Geological and Geophysical Atlas of the Indian Ocean. M., 1975; Kanaev V. F. Bottom relief of the Indian Ocean. M., 1979; Indian Ocean. L., 1982; Udintsev GB Regional geomorphology of the ocean floor. Indian Ocean. M., 1989; The lithosphere of the Indian Ocean: according to geophysical data / Ed. A.V. Chekunov, Yu.P. Neprochnov. K., 1990; Neiman V.G., Burkov V.A., Shcherbinin A.D. Dynamics of the Indian Ocean. M., 1997; Pushcharovsky Yu. M. Tectonics of the Earth. Fav. works. M., 2005.Vol. 2: Ocean tectonics.
M. G. Deev; N.N. Turko (geological structure).
The Indian Ocean by volume accounts for 20% of the World Ocean. It is bounded by Asia in the north, Africa in the west, and Australia in the east.
In the zone of 35 ° S lat. passes the conditional border with the Southern Ocean.
Description and characteristics
The waters of the Indian Ocean are renowned for their transparency and azure color. The fact is that few freshwater rivers flow into this ocean, these "troublemakers". 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 is located - the Red Sea.
And the ocean is also rich in minerals. The area near Sri Lanka has been famous for its pearls, diamonds and emeralds since antiquity. 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, the greatest depth is the Sunda Trench (7729 m).
Average temperature: 17 ° C, but in the north the waters warm up to 28 ° C.
Currents: two cycles are conditionally distinguished - northern and southern. Both move clockwise and are separated by Equatorial Countercurrent.
Major currents of the Indian Ocean
Warm:
North 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 stream is directed to the south, where it merges with the equatorial countercurrent.
South Passatnoye- begins at the islands of Oceania and moves from east to west up to the island of Madagascar.
Madagascar- branches off from the South Passat and flows parallel to Mozambique from north to south, but slightly east of the Madagascar coast. Average temperature: 26 ° C.
Mozambican Is another branch of the South Tradewind Current. It washes the shores of Africa and merges with the Agulhas in the south. The average temperature is 25 ° C, the speed is 2.8 km / h.
Agulhas, or the current of Cape Agulhas- a narrow and fast current that runs along the eastern coast of Africa from north to south.
Cold:
Somali- current off the coast of the Somali Peninsula, which changes its direction depending on the monsoon season.
Current of the westerly winds encircles the globe in southern latitudes. In the Indian Ocean from it the South Indian, which near the coast of Australia turns into the Western Australian.
Western Australian- moves from south to north along the western coast of Australia. As it approaches 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 is rich and diverse in species terms.
The coast of the tropics is represented by vast thickets of mangroves, which are home to numerous colonies of crabs and amazing fish - mudskippers. Shallow waters are a great habitat for corals. And in temperate waters grow brown, calcareous and red algae (kelp, macrocysts, fucus).
Invertebrates: numerous molluscs, a huge number of crustacean species, jellyfish. There are many sea snakes, especially venomous ones.
Sharks of the Indian Ocean are a special pride of the water area. The largest number of shark species live here: blue, gray, tiger, great white, mako, etc.
Of the mammals, dolphins and killer whales are the most numerous. And the southern part of the ocean is a natural habitat for many species of whales and pinnipeds: dugongs, fur seals, and seals. Of the birds, most of all are penguins and albatrosses.
Despite the richness of the Indian Ocean, seafood fishing is underdeveloped here. The catch is only 5% of the world. Tuna, sardines, stingrays, lobsters, lobsters and shrimps are harvested.
Indian Ocean exploration
The coastal countries of the Indian Ocean are the centers of ancient civilizations. That is why the development of the water area began much earlier than, for example, the Atlantic or the Pacific Ocean. Approximately 6 thousand years BC. the waters of the ocean were already plowed by the shuttles and boats of the ancient people. The inhabitants of Mesopotamia sailed to the shores of India and Arabia, the Egyptians carried on a lively maritime trade with the countries of East Africa and the Arabian Peninsula.
Key dates in the history of ocean exploration:
VII century A.D. - Arab sailors compile detailed navigation maps of the coastal zones of the Indian Ocean, explore the waters off the eastern coast of Africa, India, the islands of Java, Ceylon, Timor, Maldives.
1405-1433 - Zheng He's seven sea voyages and exploration of trade routes in the northern and eastern parts of the ocean.
1497 - the voyage of Vasco de Gama and the exploration of the eastern coast of Africa.
(Vasco de Gama expedition in 1497)
1642 - two raids of A. Tasman, exploration of the central part of the ocean and the discovery of Australia.
1872-1876 - the first scientific expedition of the British corvette Challenger, studying the biology of the ocean, relief, currents.
1886-1889 - expedition of Russian researchers led by S. Makarov.
1960-1965 - International Indian Ocean Expedition, established under the auspices of UNESCO. Study of hydrology, hydrochemistry, geology and biology of the ocean.
1990s - today: ocean exploration with satellites, detailed bathymetric atlas.
2014 - after the crash of the 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 fauna in the Indian Ocean have an unusual property - they glow. In particular, this explains the appearance of glowing 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 past century, this has happened to three ships at once: the Cab Cruiser, the Houston Market and Tarbon tankers.
The second unites the southern parts of the three oceans. In the northern part of the Antarctic region, the Notal-Antarctic subregion is usually distinguished (A.G. Voronov, 1963).
The flora and fauna of the Indian Ocean
The flora and fauna of the tropical region of the Indian Ocean have much in common with the organic world of the low latitudes of the Pacific Ocean, especially its western regions, which is explained by the free exchange between these oceans through the seas and straits of the Malay Archipelago. The region is distinguished by an exceptional abundance of plankton.
Phytoplankton are mainly represented by diatoms and peridineas, as well as blue-green algae. During periods of abundant development of the unicellular alga Trichodesmius, "blooming" is observed - its surface layer becomes cloudy and changes color. The composition of zooplankton is diverse, especially numerous are radiolarians, foraminifers, copepods, amphipods, etc. The plankton of the Indian Ocean is characterized by a large number of organisms glowing at night (peridineas, ctenophores, tunicates, some jellyfish, etc.). The main representatives of plankton in the temperate and Antarctic zones are diatoms, which develop here no less luxuriant development than in the Antarctic waters of the Pacific Ocean, copepods, and euphoazids. The phytobenthos of the tropical region of the Indian Ocean is distinguished by the wide development of brown algae (sargassum, turbinarium), of the green ones, caulerpa has a significant distribution. Calcareous algae (lithothamnia and khalemeda) are characteristic, which together with corals participate in the construction of reefs. The phytobenthos of the Antarctic region is distinguished by the development of red (porphyry, gelidium) and brown (fucus and kelp) algae, among which there are giant forms. The zoobenthos of the Indian Ocean is represented by a variety of molluscs, echinoderms, crustaceans, sponges, bryozoans, etc. The tropical ocean is one of the areas where coral polyps are widespread and the development of reef structures.
The Indian Ocean necton is also diverse. Among the coastal fish are numerous sardinella, anchovies, horse mackerel, small tuna, mullet, sea catfish. In the bottom ichthyofauna of the shelf - perches, flounder, stingrays, sharks, etc. The open part of the ocean is characterized by flying fish, coryphans, tuna, sharks, etc. Notothenium and white-blooded fish live in the waters of the southern part of the ocean. Among the reptiles there are giant sea turtles, sea snakes. The world of mammals is interesting - these are cetaceans (toothless and blue whales, sperm whales, dolphins), seals, elephant seals, an endangered dugong (from the order of lilacs). Some birds - gulls, terns, cormorants, albatrosses, frigates - play a significant role in the life of the ocean, and penguins in the South Pole coastal fauna.
A characteristic element of the landscapes of the tropical coasts of the Indian Ocean are mangroves with a peculiar fauna (numerous oysters, sea acorns, crabs, shrimps, hermit crabs, mudskipper fish, etc.).
The ocean area belonging to the tropical Indo-Pacific biogeographic region is characterized by a high degree of endemism in the organic world.
There are very numerous endemics in the composition of echinoderms, ascidians, coral polyps and other invertebrates. Among tropical fish, there are more than 20 families that are characteristic only of the Indian Ocean and the western part of the Pacific (terapone, sillag, silver belly, flat-headed, etc.). Among the endemic animals of the region are sea snakes, and from coastal mammals - dugongs, whose range extends from about. Madagascar and the Red Sea to Northern Australia and the Philippines.
In the tropical zone of the Indian Ocean, the Red Sea is characterized by the greatest endemism, which is probably associated with the high temperature (21-25 ° C at a depth of 200 meters) and the salinity of this reservoir (species of sea lilies, molluscs, crustaceans, fish and other animals). The degree of endemism of the organic world of the Antarctic biogeographic region is high (90% of fish are endemic), but all these plants and animals are also characteristic of the southern parts of the Pacific Ocean and the Atlantic Ocean.
Biological resources of the Indian Ocean
Biological productivity in the Indian Ocean, like in other oceans, is extremely unevenly distributed. The largest primary production is confined to coastal areas, especially the northern part of the ocean (250-500 mg * s / m 2).
First of all, the Arabian Sea stands out here (up to 600 mg * s / m2), which is explained by seasonal (summer) upwelling. The equatorial, temperate and subantarctic zones are characterized by average values of productivity (100-250 mg * s / m 2). The smallest primary production is observed in the southern tropical and subtropical latitudes (less than 100 mg * s / m2) - in the zone of the South Indian baric maximum.
Biological productivity and total biomass, as in other oceans, sharply increase in the waters adjacent to the islands and in various shallow waters.
Apparently, they are not inferior to the resources of the Pacific and Atlantic oceans, but are currently used extremely poorly.
So, the Indian Ocean accounts for only 4-5% of the world fish catch. This is about 3 million tons per year, and more than 1.5 million tons are provided only by India. In the open waters of the tropical zone, there is one type of industrial fishing - tuna fishing. Along the way, the objects of fishing are swordfish, marlins, sailboats, and some sharks. In coastal areas, commercial value is played by sardinella, mackerel, anchovies, horse mackerel, perch, red mullet, bombed, eels, stingrays, etc. Many lobsters, shrimps, various molluscs, etc. are harvested from invertebrates. The development of resources on the shelf of the southern part of the ocean began relatively recently. The main fish species here are notothenium fish and krill. Whaling, which until recently played a significant role in the southern Indian Ocean, has now significantly decreased due to a sharp decrease in the number of whales, some species of which were almost completely exterminated. Only sperm whales and sei whales have retained sufficient numbers for fishing.
Overall, the potential for a significant increase in the use of biological resources The Indian Ocean appears to be very real, and such an increase is projected for the near future.
Our planet is luxurious in every way: a huge variety of vegetation, untold wealth fauna and an endless abundance of aquatic life. All this and much more is contained on our most beautiful Earth.
Surely everyone knows that there are four immense oceans on our planet. They are all great in their own way. Quiet, for example, the largest, the Atlantic is salty, the Arctic is the coldest, and the Indian is the warmest. It is to the latter that we will devote our article.
Did you know that the Indian Ocean is considered the third largest? Its area is no less than 76.17 million km2, which is 20% of the entire globe. So what secrets does our mysterious hero keep? Let's figure it out below.
General location information
In the north, the ocean washes mysterious Asia, in the east - adventurous Australia, in the west - sunny Africa, and in the south - frosty Antarctica. The highest point of the Indian Ocean is located at 30 o meridian of northern latitude. It is located in the Persian Gulf. The border with the Atlantic Ocean runs along the 20 o meridian of east longitude, and the border with the Pacific Ocean - at 146 o 55 of the same longitude. The length of the Indian Ocean is 100,000 km.
A few words about history
Some areas of ancient civilizations were located exactly on the shores of our hero. Researchers claim that one of the very first navigation was carried out on the waters of the Indian Ocean, about 6 thousand years ago. Arab sailors described the ocean route in detail. The first geographic information appeared in the 90s of the 15th century, even during the life of Vasco de Gama himself, who was the first in history to overcome the path from Europe to India. It was he who spoke about the innumerable water beauties that the Indian Ocean provided.
The depth of the ocean was first measured by the world famous sailor James Cook, famous for his round-the-world expeditions and numerous discoveries in the field of geography. Back in the 19th century, members of one of the famous English expeditions that plowed endless expanses on the famous ship Challenger began to study the ocean in all respects.
Which countries is washed by the Indian Ocean?
This giant washes a huge number of states, both mainland and insular.
Mainland countries of the Indian Ocean:
Australia;
Thailand;
Saudi Arabia;
Indonesia;
Pakistan;
Malaysia;
Mozambique;
Bangladesh;
Indian Ocean Island Countries:
Mauritius;
Maldives;
Sri Lanka;
Madagascar;
Seychelles.
Here is such a vast Indian Ocean.
Ocean depth
The Indian Ocean has five seas. They form the depth and area of our hero. So, for example, the Arabian Sea is one of the deepest in the Indian Ocean. The significant point is located on the mid-ocean ridge, in its center, where the rift valley is located. The depth above it is no less than 3600 m. The deepest point of the Indian Ocean is located near the island of Java, in the Javan depression, and is 7455 m. Unlike the Pacific Ocean, this is not enough, because its maximum depth is 11022 m. ( Mariana Trench).
Indian Ocean climate
Most of the ocean lies in the tropical, equatorial and subequatorial zones, only its southern region is located in high latitudes.
The climate is represented by monsoons and seasonal winds in the northern part of the ocean. There are two seasons in this area: warm, calm winters and hot, rainy, cloudy, stormy summers. Closer to the south, the southeast trade wind dominates. In temperate latitudes, a strong westerly wind constantly prevails. The maximum amount of precipitation is observed in (about 3000 mm per year). The minimum is off the shores of the Red Sea, Arabia, in the Persian Gulf.
Salinity
The maximum indicators of salinity of the surface waters of the Indian Ocean are in the Red Sea and the Persian Gulf (41%). Also enough high coefficient salinity is also observed in the southern tropics in the eastern part. As we move towards the Bay of Bengal, the figures drop significantly - up to 34%.
The increase in the salinity coefficient largely depends on precipitation and evaporation.
The minimum indicators are typical for the territory of Antarctic waters. As a rule, this coefficient in this area is influenced by the melting of glaciers.
Temperature
The temperature of the Indian Ocean on the surface of the water is +29 o C. This is the highest indicator. Less observed off the African coast, where the Somali current runs - + 22-23 o C. At the equator, the surface water temperature averages + 26-28 o C. If you move further south, it reaches -1 o C (off the coast of Antarctica).
Icebergs also make their contribution to temperature changes, which in rare cases swim into the territory of southern latitudes.
As you can see, the average temperature of the Indian Ocean is generally high, which is why our hero was awarded the title of "the warmest ocean in the world."
Gulfs
The Indian Ocean has 19 bays (3 of them belong to the Red Sea):
Indian Ocean Gulfs Red Sea
- Aqaba. In recent years, it has acquired resort significance. Length - 175 km, width - 29 km. The western bank belongs to Egypt, the eastern one belongs to Saudi Arabia, the northern one belongs to Jordan and Israel.
- Makadi. It attracts tourists with its amazing coral shores. It is a bay stretching for 30 km along the coast of the Red Sea.
- Separates the Asian Sinai Peninsula from Africa. Length - 290 km, width - 55 km.
Relief
The relief of the Indian Ocean is characterized by the presence of a ridge at its depth called the Indian Central Ridge. It stretches along the western shores of Hindustan. On average, the depth above it is 3.5 km. In some places, it decreases and is already about 2.4 km. After that, the ridge branches out. The first branch goes eastward and reaches the Pacific Ocean, almost touching Antarctica, and ends at the Australian-Antarctic uplift, the depth above which is 3.5 km.
Another branch goes to Antarctica to the south and ends with a ridge called Kargelen-Hausberg, the minimum depth above which is 0.5 km, the maximum depth is 2.3 km.
The Central Indian Ridge divides the ocean into two parts of different sizes: the western and the eastern. In the eastern part of the Indian-Australian and South Australian basins are located, the depths above which vary from 500 to 7455 m. In the northeastern part of the Indian-Australian basin is the deepest depression, which has the Indian Ocean. The depth of the ocean, more precisely, its maximum point, is near (7455 m).
The bottom of the Indian Ocean in the western relief part differs significantly from the eastern one, it is more complex in structure. This is due to the fact that on the latter, a significant increase in the bottom is quite often carried out (due to this, in most cases, small islands are formed) and an uneven arrangement of the basins.
To the north of the island of Madagascar, there is a basin called the Somali basin, the depth above which is 5.2 km. To the south of the island there is a plateau called Crozet, surrounded on all sides by hollows. The depth above it is 2.5 km. If you move to the northeast, the Central Indian Basin appears. The depth above it is 5.5 km. Between Madagascar and Crozet, a little to the north, there is a hollow called Madagascar with a depth of 5.78 km. To the south, there is a depression belonging to Cape Igolny, the depth above which is 5.5 km. The relief of the Indian Ocean towards Antarctica is characterized by the presence of a subsidence of the bottom. The depth above this area reaches 5.8 km.
Flora and fauna
The nature of the Indian Ocean is diverse and very interesting. It is home to animals and plants that are used to regular droughts and floods.
Many tropical shores of the Indian Ocean are represented by mangroves, or rhizophores. Numerous species of crabs live in this area. A fish called mudskipper inhabits almost the entire territory of the mangrove region of the Indian Ocean.
In the shallow areas of tropical waters, corals have taken root with fish and numerous invertebrates living on them.
In temperate zones, brown, blue-green grow and most of them are kelp, microcystis and fucus. Among phytoplankton, diatoms predominate, and in tropical zones, peridineas.
The most famous crayfish in to a greater extent prevail in the Indian Ocean, are copepods. Now there are more than 20 thousand species of them. In second place among the animals living in this ocean are jellyfish and squid. Among the fish are known tuna, sailfish, coryphans and light anchovies.
We have chosen the territory of the ocean and dangerous species of animals. Sharks, crocodiles and Poisonous snakes regularly instill fear in local residents.
The mammals in the Indian Ocean are dominated by dolphins, whales, dugongs and seals. The birds are penguins, albatrosses and frigates.
Pool
The Indian Ocean basin is quite diverse. It includes African rivers - Zambezi and Limpopo; the largest Asian rivers - Ayeyarwaddy, Salween; The Euphrates and Tigris, which merge just above the confluence with the Persian Gulf; Indus, flowing into the Arabian Sea.
Fishing and seafood
The coastal population has been engaged in economic activities for a long time. To this day, fishing and seafood fishing is of great importance for the economy of many countries that are washed by the Indian Ocean. The depth of the ocean provides rich gifts to people, for example, in Sri Lanka, in the north-west of Australia and in the Bahrain Islands, there is an intensive mining of mother-of-pearl and pearls.
Near Antarctica, people are actively engaged in whale fishing, and tuna fishing is carried out near the equator.
The Persian Gulf contains rich sources of oil, both on the coastal territory and under water.
Environmental problems of the Indian Ocean
Human activities have had dire consequences. Ocean waters began to become significantly polluted, which gradually leads to the extinction of some species of marine life. For example, several species of cetaceans at the end of the 20th century were threatened with complete extinction. The number of sei whales and sperm whales has significantly decreased.
In the 80s of the 20th century, a complete ban on hunting for whales was introduced by the Whale Fishing Commission. Violation of the moratorium was strictly punishable by law. But in 2010, under the influence of countries such as Japan, Denmark, Iceland, the ban, unfortunately, was canceled.
A great danger to marine life is the pollution of ocean waters with oil products, all kinds of wastes from the nuclear industry and heavy metals. Also, the routes of oil tankers, which deliver oil from the Persian Gulf to European countries, pass through the ocean. If an accident occurs suddenly on such a transport, then this will lead to the mass death of underwater inhabitants.
Studying geography is quite interesting, especially when it comes to marine beauty and inhabitants. The 7th grade of a comprehensive school studies the Indian Ocean in most detail. Children enthusiastically listen to everything that the teacher tells about this beautiful and mysterious giant, which is teeming with a variety of vegetation and the richness of the animal world.