If you are asked how many oceans there are on the planet, I think you will be somewhat bewildered, unless, of course, you were good at geography in school, you will answer four (Pacific, Arctic, Atlantic, Indian) and you will be... wrong, because since 2000 there were five of them. Fifth was the Southern Ocean (or Antarctic Ocean).
Southern Ocean (or Antarctic Ocean)- the fourth largest ocean on Earth, surrounding Antarctica.
This ocean was first identified in 1650 by the Dutch geographer B. Varenius, and until the 1st quarter of the 20th century the name “Southern Ocean” was placed on maps and atlases, while in many countries the territory of Antarctica was also included in it, since the ice continent was considered to the ocean region and its border the latitude of the Antarctic Circle was adopted.
From the 2nd quarter of the 20th century, the boundary of the Southern Ocean began to be drawn from 35° S. (based on water and atmospheric circulation) up to 60° S. (according to the nature of the bottom topography). In the Soviet Atlas of the Antarctic (vol. 2, 1969), the northern boundary of the Antarctic convergence zone, located near 55° S, is accepted as the boundary of the Southern Ocean.
In the spring of 2000, the International Hydrographic Organization decided to declare the water area north of the coast of Antarctica to 60° south latitude a separate ocean - the Southern Ocean. The decision is based on the latest oceanographic data indicating the uniqueness of the waters surrounding Antarctica. IN Russian tradition The Southern Ocean is a relative concept. Its approximate boundary is considered to be the Antarctic Convergence Zone (the northern limit of Antarctic surface waters). In other countries, the border is also blurred - the latitude south of Cape Horn, the border of floating ice, the Antarctic Convention zone.
The ocean area is 86 million km 2, the average depth is 3500 m, the maximum depth is (South Sandwich Trench) 8428 m. Off the coast of Antarctica there are 13 seas: Weddell, Scotia, Bellingshausen, Ross, as well as Amundsen, Davis, Lazarev, Rieser -Larsen, Cosmonauts, Commonwealth, Mawson, D'Urville, Somov. The most important Southern Ocean Islands: Falkland (Malvinas), Kerguelen, South. Georgiy, South. Shetland, South Orkney, South Sandwiches. The Antarctic shelf is submerged to a depth of 500 m.
Intense cyclonic activity has developed over the Southern Ocean. Most cyclones move from west to east. Air temperature in January, off the coast of Antarctica, it does not exceed 0°С (-6°С in the Weddell and Ross seas), at 50° south latitude. in the Indian and Atlantic sectors increases to 7°C, and to 12°C in the Pacific. In winter, the contrasts are even greater: in the coastal zone the average temperature drops to -20°C (in the Weddell and Ross Seas to -30°C), and at 50° S. latitude. is 2-3°C in the Atlantic and Indian sectors and 6-7°C in the Pacific.
Main feature of the Southern Ocean- the current of westerly winds, which spreads throughout the entire thickness of the waters and transports them in an easterly direction. To the south of this current, the Western Coastal Current is formed. Cold and dense water masses from the shores of Antarctica flow along the ocean floor far to the north.
The ice cover of the Southern Ocean is more developed in the Western Hemisphere and varies greatly with the seasons: in September-October its area is 18-19 million km 2, and in January-February - only 2-3 million km 2.
Average width of the drifting ice belt in November at 30° W. length is 2000 km, at 170° west. d. - 1500 km, at 90-150° east. d. - 250-550 km.
Icebergs are constantly calving off the Antarctic Ice Sheet. At the same time, there are more than 200 thousand icebergs in the Southern Ocean, average length equal to 500 m, but there are giants up to 180 km long and several tens of kilometers wide. Icebergs are carried to the north and can be found even at 35-40° S. They exist in the ocean for an average of 6 years, but in some cases their age can exceed 12-15 years.
Despite the harsh climate, the Southern Ocean is rich in life. There are huge masses of phyto- and zooplankton, krill, sponges and echinoderms are abundant, several families of fish, especially notothenia. Among the birds, petrels, skuas, and penguins are numerous. There are many whales in the ocean (blue whale, fin whale, sei whale, humpback whale, etc.) and seals (Weddell seal, crabeater seal, leopard seal, fur seal). Whaling is prohibited, but a lot of krill and fish are caught.
Oceanologist of the Department of Marine Forecasts
Kitchenko N.V.
The Southern Ocean is the part of the World Ocean that covers the waters of the Pacific, Indian and surrounding Antarctica.
The Southern Ocean was formed approximately 30 million years ago when South America separated from Antarctica, forming the Drake Passage.
The Southern Ocean contains a huge amount of plankton and krill - the main elements of the diet of whales. One of the most common species of whale in the Southern Ocean, the humpback is also one of the most agile whales, loving to perform spectacular acrobatic stunts, jumping high out of the water.
On most marine navigation charts there is no such thing as the Southern Ocean at all. Sailors also do not use it for practical purposes. Moreover, there is no agreement in the scientific community regarding precise definition its borders.
The boundaries of this ocean are extremely arbitrary because the very definition of the location of the ocean is in question. It was marked as a separate ocean on maps as early as 1650 by the geographer of German-Dutch origin Bernhard Waren, also called Bernhardus Warenius (1622-1650). In the last year of Varenius’s life, his main work “General Geography: a general scientific systematized description of the surface of the Earth” was published, in which Varenius tried to collect all the geographical knowledge accumulated by that time by humanity.
The reason why Varenius combined the Antarctic regions of the three oceans into one - the Southern - is that at that time all other regions above the Antarctic Circle had not yet been discovered.
In 1845, the Royal Geographical Society in London tried to introduce the name "Southern Ocean", but it did not catch on.
Southern Ocean was present geographical maps until the beginning of the 20th century. In 1937, the International Hydrographic Organization used the name "Southern Ocean" in a number of publications. Moreover, many editions of geographical atlases referred to the Southern Ocean and the territory of the ice-covered continent of Antarctica. In this case, the latitude of the Antarctic Circle (66°33"44"" S) was considered the boundary of the Southern Ocean.
By the beginning of the 20th century. The southern regions of the three oceans had already been sufficiently studied, and disputes began in the scientific community regarding the boundary of the Southern Ocean. Each science considered its own way of determining the boundaries of the ocean to be the only correct one. Hydrologists and climatologists drew the boundary of the Southern Ocean based on the circulation of water and the atmosphere: 35° S. w. Marine geologists, having studied the nature of the bottom, insisted on drawing the boundary at 60° south. w. Oceanologists of the USSR, when compiling the Atlas of the Antarctic in 1969, drew the boundary of the Southern Ocean at 55° south. w. - the northern border of the Antarctic convergence zone (the zone of convergence of northern, relatively warmer, and southern, cold surface waters).
In 2000, the International Hydrographic Organization accepted the division into five oceans, but this decision was not finally ratified.
Since the identification of a separate ocean had no practical significance, the issue of the Southern Ocean gradually disappeared from the practice of navigation, and it ceased to be mentioned in maritime manuals. Currently, the topic of the Southern Ocean is sometimes raised by scientists specializing in very narrow branches of oceanology.
The issue of the boundary of the Southern Ocean has remained controversial, but as a compromise, most experts draw the northern boundary at 60° N. sh., and the southern one - along the coast of Antarctica. In accordance with this, the Southern Ocean can be considered the fourth largest by area.
Geography
The Southern Ocean is located in the South Polar region of the Earth. Most often this is the name given to the southern parts of the Atlantic, Indian and Pacific Oceans adjacent to Antarctica. The southern boundary of the ocean is considered to be the coast of Antarctica; the northern boundary is conventionally drawn approximately along the parallel of 60° S. w. Here (more precisely, up to 55° S) is the northern limit of Antarctic surface waters (Antarctic Circumpolar Current).
The sailors nicknamed the “Roaring Forties” the oceanic space between 40° and 50° latitude in the Southern Hemisphere of the Earth, where strong and persistent westerly winds constantly blow, causing frequent storms.
A distinctive feature of the Southern Ocean is the atmospheric circulation of air masses moving a considerable distance over the open ocean, never encountering barriers in the form of mountains or large areas of flat land.
Intense cyclonic activity is extremely developed over the Southern Ocean. Most cyclones move from west to east. This zone is part of the region between the 60th and 70th parallels of south latitude, called the “howling sixties” due to the strong winds that constantly dominate the region, reaching speeds of 145 km/h and raising waves 15 m high and higher.
One more distinctive feature Southern Ocean - the current of the Western winds, which spreads throughout the entire thickness of the waters and transports them in an easterly direction. To the south of this current, the Western Coastal Current forms. The cold and dense water masses formed here move from the shores of Antarctica along the ocean floor far to the north.
It is here in the Southern Ocean that the largest icebergs form, constantly breaking off from the Antarctic Ice Sheet. At the same time, there are more than 200 thousand icebergs in the Southern Ocean. The average length of an iceberg is about 500 m, but there are colossal ice floes up to 180 km long and several tens of kilometers wide. Currents carry icebergs to the north, and they can even reach 35-40° S. sh.: a significant mass melts under the sun long time. Average duration The existence of an iceberg in the Southern Ocean is 6 years, but there are also “veterans” aged 12-15 years.
Flora and fauna
The climatic conditions for the flora and fauna of the Southern Ocean only seem harsh. On the contrary, plants and animals have perfectly adapted to use cold as a protective element. The Southern Ocean is distinguished by gigantic accumulations of phyto- and zooplankton, krill; many species of sponges and echinoderms live on the bottom. There are several families of fish here, but nototheniids predominate.
The birds are very unique: the southern giant petrel, black-browed albatross, and skua are able to travel long distances by air, and the flightless penguin can walk on ice. The abundance of food explains the exceptional species diversity whales (blue whale, fin whale, sei whale, humpback whale) and seals (Weddell seal, crabeater seal, leopard seal, fur seal). Industrial fishing for cetaceans has seriously reduced their numbers, and whaling is now prohibited. Other dangers threatening the number of local fauna include poaching overfishing and the breeding of rats on the Antarctic islands, where the number of bird nests is very high.
Population
On the islands and continental coast South Sea the population is fickle and small: they are primarily polar explorers. In accordance with the Convention on Antarctica, there cannot be any other settlers there, since the continent and islands located south of 60° S. sh., cannot belong to any state, and only scientific activity. Unfortunately, this does not mean that the states party to the convention have no territorial claims: very large territories on the continent are claimed by Great Britain, Norway, Australia, since 1908 by Great Britain, since 1940 by Chile, since 1943 by Chile. Argentina. The USA and Russia also have their sights on them. Since 1929, Norway has laid claim to the island of Peter I. There are also a number of disputed islands in the Southern Ocean, but all of them have no permanent population; only in the summer are the islands visited by scientific expeditions.
General information
Location: Southern Hemisphere.Composition: water area around Antarctica (southern regions of the Atlantic, Indian and Pacific oceans).
Seas: Atlantic Ocean (Lazarev, Rieser-Larsen, Scots), Indian (Davis, Cosmonauts, Mawson, Commonwealth), Pacific (Amundsen, Bellingshausen, D'Urville, Somov).
Geographical boundaries: northern - 60° S. sh., southern - the coast of Antarctica.
Largest islands: Rossa, Adelaide, archipelagos: Palmera South Shetland Islands, South Orkney Islands, including the largest Antarctic islands completely surrounded by shelf ice: Alexander Land, Berkner, Thurston.
Numbers
Area: 20.327 million km2.Average depth: 3500 m.
Maximum depth: South Sandwich Trench (Atlantic Ocean, 8428 m).
Antarctic shelf depth: up to 500 m.
Ice cover area in September-October: 1819 million km 2, in January-February - 2-3 million km 2.
■ Natural: Ross Ice Shelf, Una Peaks (Le Mer Channel), Banger Oasis (western Wilkes Land), table-shaped icebergs, bird colonies.
Curious facts
■ The 60th parallel of latitude is not only the northern limit of the Southern Ocean, but also the northern limit of the demilitarized nuclear-weapon-free zone (Antarctic Treaty 1959).
■ In the Northern Hemisphere of the Earth, 61% of its surface is occupied by water, and in the Southern Hemisphere - 81%.
■ In the Southern Ocean there are sectors: Atlantic - between the northern tip of the Antarctic Peninsula and the meridian of the Cape of Good Hope, Indian - between the meridian of the Cape of Good Hope and the meridian of the South East Cape on the island of Tasmania, and Pacific - between the meridian of the South East Cape on the island of Tasmania and the northern tip of the Antarctic Peninsula.
■ The South Sandwich Trench is not only the deepest in the Southern Ocean, but also the second deepest in Atlantic Ocean- after the Puerto Rico trench (8742 m).
■ Most of the southern ocean species of fauna that live at water temperatures close to freezing (up to -1.9 ° C) have in the blood and other body fluids a kind of automobile “anti-freeze”: glycoproteins - a special connection of sugars with proteins that prevents the formation of ice in the body.
■ The grey-headed albatross is listed in the Guinness Book of Records as the bird with the fastest horizontal flight: 127 km/h - the speed that the albatross maintained for more than 8 hours returning to its nest on South Georgia Island. The wandering albatross, which lives there, has the largest wingspan among birds: up to 325 cm.
■ Another record holder among Antarctic birds is the gentoo penguin from the Falkland Islands, which reaches a speed of 36 km/h underwater - the fastest of all penguins.
Representatives of the older generation studied 4 oceans in geography lessons at school: the Pacific, Atlantic, Indian and Arctic. However, not so long ago, part of the educational community identified a fifth ocean - the Southern. The International Hydrographic Association has agreed to highlight this ocean since 2000, but this decision is still not recognized by everyone.
What is the Southern Ocean? Who discovered it and under what circumstances? Where is it? Which shores does it wash and what currents circulate in it? Answers to these and many other questions await you in the article.
History of exploration of the fifth ocean
In the 21st century, there are no unexplored places left on the world map for humans. Technological progress made it possible not only to see previously inaccessible territories on a satellite image, but also to get there relatively comfortably.
During new history neither existed yet space satellites, no powerful icebreaker ships capable of breaking through the permafrost layer, no internal combustion engines. Man only had his own physical strength and mental flexibility. It is not surprising that the first mentions of the Southern Ocean are theoretical.
First mention of the ocean
Back in the 17th century, in 1650, the Dutch geographer Verenius declared the existence of a continent in the southern, as yet unexplored, pole of the Earth, washed by ocean waters. The idea was initially expressed in the form of a theory, since humanity was unable to unambiguously confirm or refute it.
"Random" discoveries
Like many geographical discoveries, the first “swims” towards the South Pole occurred by accident. Thus, Dirk Geeritz's ship was caught in a storm and lost its course, sailing beyond 64 degrees south latitude and hitting the South Orkney Islands. South Georgia, Bouvet Island, and Kargelan Island were explored in a similar way.
The first expeditions to the South Pole
In the 18th century, maritime powers actively explored this region. Until this time, no targeted exploration of the pole had been carried out.
One of the first serious expeditions to the southern part globe historians call the expedition of the Englishman Cook, who passed the Arctic Circle at 37 degrees east longitude. Having run into impenetrable ice fields, having spent considerable strength to overcome them, Cook had to turn his ships around. In the future, he created such a colorful description of the Southern Ocean that the next daredevil set off to storm the South Pole only at the beginning of the 19th century.
Bellingshausen expedition
In the early thirties of the 19th century, the Russian explorer Bellingshausen circled the South Pole for the first time in history. At the same time, the navigator discovered the island of Peter I and the Land of Alexander I. Particular weight is given to the traveler’s merit by the fact that he traveled on light, maneuverable ships, not at all designed to deal with ice.
Dumont-Derville Expedition
The French campaign in 1837 culminated in the discovery of the Land of Louis Philippe. The expedition also discovered Adélie Land and the Clary Coast. The expedition was complicated by the fact that Dumont-Derville's ships were “captured” by the ice, from which they had to be rescued with the help of ropes and manpower.
American expeditions
The then “young” United States of America made a significant contribution to the research of the Southern Ocean. During the expedition of 1839, a group of ships led by Villiers tried to pass from the Tierra del Fuego Archipelago to the south, but ran into ice barriers and turned around.
In 1840, an expedition led by Wilkes discovered part of the territory of East Antarctica, which later received the name “Wilkes Land”.
Where is the Southern Ocean?
Geographers call the southern part of the World Ocean, consisting of the southernmost parts of the Indian, Pacific, and Atlantic. The waters of the Southern Ocean wash Antarctica on all sides. The fifth ocean does not have such clear island boundaries as the other four.
Today, it is customary to limit the boundaries of the Southern Ocean to the 60th parallel of southern latitude - an imaginary line encircling the Southern Hemisphere of the Earth.
The problem of determining the actual boundaries is quite relevant today. Researchers have tried to delineate the boundaries of the fifth ocean using the currents of the Southern Ocean. This attempt was unsuccessful, as the currents gradually changed their trajectory. It also proved problematic to establish the island boundaries of the “new” ocean. Thus, the clear answer to the question of where the Southern Ocean is located is: beyond the 60th parallel of south latitude.
Some interesting facts
The deepest point of the fifth ocean is almost 8300 meters (South Sandwich Trench). The average depth is 3300 meters. The length of the ocean coast reaches 18 thousand kilometers.
The extent of the Southern Ocean from north to south is determined very arbitrarily, since there are no reference points from which to count. Until now, geographers do not have a common opinion about the boundaries of the ocean.
What seas does the fifth ocean consist of?
Oceans are the largest hydrographic objects in modern geography. Each consists of several seas adjacent to land or expressed by the Earth's relief under water.
Consider the ocean. Today, geographers identify 20 seas that are part of the “new” ocean. Five of them were discovered by Russian and Soviet researchers.
| Name of the sea | |
| Sea of Lazarev | From 0 to 15 degrees east longitude |
| Sea of King Haakon VII | From 20 to 67 degrees south latitude |
| Rieser-Larsen Sea | From 14th to 34th degrees east longitude |
| Weddell Sea | From 10 to 60 degrees west longitude, from 78 to 60 degrees south latitude |
| Sea of Cosmonauts | From 34th to 45th degree east longitude |
| Sea of Scotia | From 30 to 50 degrees east longitude, from 55 to 60 degrees south latitude |
| Commonwealth Sea | From 70 to 87 degrees east longitude |
| Bellingshausen Sea | From 72 to 100 degrees west longitude |
| Davis Sea | From 87th to 98th degrees east longitude |
| Amundsen Sea | From 100 to 123 degrees west longitude |
| Mawson Sea | From 98th to 113th degrees east longitude |
| Ross Sea | From 170 degrees east longitude to 158 degrees west longitude |
| Sea of D'Urville | From 136th to 148th degrees east longitude |
| Sea of Somov | From 148 to 170 degrees east longitude |
It should be noted that geographers rarely distinguish the King Haakon VII Sea due to its adjacent territories with the Lazarev Sea. However, the Norwegian side, which discovered it, insists on separating the Sea of King Haakon VII and does not recognize the boundaries of the Lazarev Sea.
Southern Ocean Currents
The main current characteristic of the ocean is the Antarctic Current - the most powerful flow of water in the World Ocean. Geographers call it Circular because it flows around the continent - Antarctica. This is the only current that crosses absolutely all meridians of the globe. Another, more romantic name is the current of the Western Winds. It carries its waters between the subtropical zone and the Antarctic zone. If expressed in degrees, then it flows within 34-50 degrees south latitude.
Speaking about the flow of the Western Winds, one cannot fail to note that interesting fact, that almost along its entire length it is divided into two symmetrical flows located at the northern and southern edges of the current. These streams capture enough high speed- up to 42 centimeters per second. Between them the current is weaker and more moderate. Thanks to this phenomenon, which encloses Antarctica with a continuous ring, Antarctic waters cannot leave their circulation. This conventional band is called the Antarctic convergence.
In addition, there is another zone of water circulation in the ocean. It is located at 62-64 degrees south latitude. Here, the current speed is noticeably weaker than in the Antarctic Convergence and amounts to up to 6 centimeters per second. Currents in this area are predominantly directed to the east.
Currents near Antarctica make it possible to talk about the circulation of water around the continent in the opposite direction - to the west. However, this theory has not been proven to date. The main reason for this is periodic changes in currents, which occur quite often.
An interesting feature of water circulation in the fifth ocean, which distinguishes it from other hydrographic objects in this category, is the depth of water circulation. The point is that the current in the Southern Ocean moves water masses not only on the surface, but also to the very bottom. This phenomenon is explained by the presence of special gradient currents that also capture deep waters. In addition, the density and homogeneity of water in the “new” ocean is higher than in others.
Ocean temperature
The temperature range on the mainland and in the surrounding ocean is very wide. The most high temperature, recorded in Antarctica, was 6.5 degrees Celsius. The lowest temperature is minus 88.2 degrees.
As for the average ocean temperature, it ranges from minus 2 degrees to 10 degrees Celsius.
Most low temperatures cover Antarctica in August, and the highest in January.
It is interesting that during the day the temperature in Antarctica is lower than at night. This phenomenon is still unsolved.
The climate of the Southern Ocean is clearly characterized by the level of continental glaciation. Scientists have found that glaciation of the continent is slowly but beginning to decrease. This suggests that the average air temperature in Antarctica and the fifth ocean is increasing. True, in this case we are talking about the so-called global warming, which covers not only the South Pole, but the entire Earth. The main proof of this theory is the parallel decrease in glaciation at the North Pole.
Icebergs
The gradual melting of Antarctic ice leads to the appearance of icebergs - huge pieces of ice that break off from the mainland and set sail across the World Ocean. The largest of them can measure hundreds of meters and cause big trouble ships they met on their way. The “lifespan” of such icebergs drifting in the ocean can be up to 16 years. This fact significantly increases the risk of damage to the ship when sailing in these latitudes.
Some testing countries are trying to use giant icebergs to mine it. To do this, icebergs are caught and towed to specially equipped places for fresh water extraction.
Ocean inhabitants
Despite the difficult climatic conditions, the ocean area is quite densely populated by fauna.
The most prominent representatives The fauna of Antarctica and the Southern Ocean are penguins. These flightless seabirds feed in waters teeming with plankton and small fish.
Of the other birds, the most common are petrels and skuas.
The Southern Ocean is the habitat of many species of whales. The humpback whale, blue whale and other species live here. Seals are also common at the south pole.
General information. The ring of oceanic waters washing Antarctica combines characteristic features separate ocean and well-defined natural features of the Atlantic, Pacific and Indian Oceans.
A difficult issue in this situation is the issue of boundaries. In the south it is limited by the coast of the southern polar continent. This ocean has no western or eastern border. According to modern scientifically based ideas, the northern border is considered to be the northern periphery of the Antarctic convergence line (a strip of convergence of relatively warm and cold surface waters) at approximately 40-50° S. sh., which is close to the northern border of the Antarctic Circumpolar Current.
The main feature of this conditional geographical boundary of the Southern Ocean is its certain changes in time and space due to interannual and interseasonal fluctuations in the position of the Antarctic convergence lines.
Within the designated boundaries, the area of the Southern Ocean is 86 million km (according to some sources, this is a controversial issue), the average depth is 3503 m, the greatest depth is 8264 m (South Sandwich Trench, Meteor). There are many islands of varying sizes scattered throughout the Southern Ocean, most of which have complex mountainous terrain. The seas are located on the southern periphery of the ocean. The Scotia Sea is unique. In the south, the seas are limited to the coast of Antarctica, and in the north they are open to the ocean.
Relief of the ocean floor. Based on modern research Geographical science, the continent and its surrounding waters lie mainly on the continental-oceanic Antarctic. Some sections of the bottom of the northern reaches of the Southern Ocean are located on other plates adjacent to the Pacific-South American plate, the Scotia Sea, etc. The features and topography of the Southern Ocean bottom are associated with this. All the main geomorphological forms are clearly expressed on the bottom; the shelf zone is characterized by a small width (on average 150 km). Only in the Ross Seas does its width reach 1000-1100 km. The average depth of the shelf zone reaches 200 m.
The continental slope of Antarctica, especially its eastern part, is dissected by steps and cut through by an abundance of underwater canyons. In the Antarctic part, the continental slope is steep near the Pacific coast and relatively flat and weakly dissected near the Antarctic coast.
The ocean floor is characterized by a number of underwater ridges, small rises and basins. The largest ranges are the West Indian and Central Indian, within which rift valleys are clearly visible. They are essentially the southern spurs of mid-ocean ridges.
Within the Southern Ocean there are the Australian-Antarctic, South Pacific and partially East Pacific rises. In the area of 60° south. w. There are large ocean basins: African-Antarctic (6787 m), Australian-Antarctic (6098 m) and Bellingshausen (5399 m).
In the general circulation of ocean waters, their vertical movement plays an important role. Between the Eastern and Western Currents, due to their divergence (divergence), deep waters enriched with nutrients rise.
Over the continental slope within the Weddell Sea in winter, cooled and saline surface waters, being heavier, sink into the deeper layers. As a result of this phenomenon, relatively cold and salty bottom waters are formed. They spread east around Antarctica and north into the Atlantic, and where they mix with their waters.
Wind waves develop in ice-free areas of the Southern Ocean. It happens most strong in winter between 40 and 60° S. w. Waves with a height of about 2 m predominate here, and during a storm they reach a height of 8-9 m. The highest ones are recorded near the Kerguelen Island (sector of the Indian Ocean) - up to 35 m. Significant waves with a wave height of 4-6 m are noted to the west of the Drake Passage and in the area to the southwest. In summer, the strength of the waves weakens, the height of the waves decreases. Area 40-60° S. w. They are usually called the “roaring forties” and the “furious fifties”.
Tides in the Southern Ocean are observed everywhere, their largest values (about 8 m) are observed in southern shores. In other areas the value is 2-2.5 m.
Ice is one of the most characteristic features nature of the Southern Ocean. They exist all year round. During maximum development (September-October), ice covers an area of 18-19 million km2, and in summer time(January-February) - only 2-3 million km2.
Sea ice (fast ice and drifting ice), shelf ice and ice are found here. To the north of the fast ice there is drifting ice. The patterns and direction of their movement are determined by winds and currents.
Between the edge of the fast ice and the drifting ice there are flaw polynyas - large spaces clean water. The presence of shelf ice is associated with the coastal strip of the shelf. This ice sedimentary origin, its continental edge is a continuation of the land cover. It lies completely on the ground. The average height of the shelf ice is 430 m, and above sea level it rises by 10 and sometimes by 50 m.
The presence of icebergs is the most significant feature of the Southern Ocean. They are formed as a result of the breaking off of coastal parts of continental and shelf ice under the influence of waves, swell and. According to available data, over 200,000 icebergs are found in the waters of the Southern Ocean every year. Their average length is about 500 m, and their height is 50 m above sea level. Individual icebergs are up to 5 km long. The bulk of icebergs melt within 3-5 years. Largest quantity icebergs are found at a distance of 100-150 km from the coast. At a distance of up to 700 km they are quite rare. Under the influence of wind and current, icebergs drift in the coastal zone of Antarctica. As they drift over time, they are destroyed and take on bizarre shapes.
Organic life in the ocean. The presence of the Antarctic Circumpolar Current in the ocean determines the composition and distribution of organic life. Huge masses of ice limit life in the ocean, but nevertheless, the Antarctic seas can compete with many tropical areas of the World Ocean in the abundance and diversity of living organisms. The long existence of flora and fauna in a little changing environment (at least 5 million years) has led to the fact that organisms have adapted to harsh living conditions. Diatoms remain viable down to a temperature of -20 °C. Fish have developed adaptations for living in supercooled water, and the inhabitants of the lower surface of the fast ice use the ice as a shelter, where rich pastures of ice algae - regrowth - are formed.
The circumpolar position of the Southern Ocean is associated with sharp seasonal dynamics of the main condition for photosynthesis - . Under such conditions, a large amplitude of quantitative changes in phytoplankton and a shift in the flowering zone from the north, where spring begins earlier, to the south, where it is delayed, are observed throughout the year. In low latitudes, two peaks of flowering have time to develop, and in high latitudes only one. IN surface waters biological latitudinal zonation is clearly expressed. The inhabitants of the bottom do not have such zoning, since in their development important role plays a role in the bottom topography and barriers that prevent the exchange of flora and fauna. In the Southern Ocean, phytoplankton is dominated by diatoms (about 180 species).
Blue-green algae make up a small number. In quantitative terms, diatoms also predominate, especially in high latitudes, where they are almost 100%. During the period of maximum bloom, the number of diatoms reaches its largest concentration.
There is a clear relationship between the distribution of algae and the vertical stability of waters. In summer, a significant mass of algae is found in the surface 25-meter layer.
In the direction from south to north, the composition of phytoplankton changes: high-latitude cold-water species gradually disappear from the flora, being replaced by warm-water ones.
Zooplankton in the waters of the Southern Ocean is represented by copepods (about 120 species), amphipods (about 80 species), etc., chaetognaths, polychaetes, ostracods, appendicularia and mollusks are of lesser importance. In quantitative terms, copepods are in first place, accounting for almost 75% of the zooplankton biomass of the Pacific and Indian sectors of the ocean. There are few copepods in the ocean sector, since euphausiids (krill) are widespread.
The Southern Ocean, especially its Antarctic regions, is characterized by massive accumulations of krill (Antarctic crustaceans). The krill biomass in these areas reaches 2,200 million tons, which makes it possible to catch up to 50-70 million tons of krill annually. Here, krill is the main food of baleen whales, seals, fish, cephalopods, penguins and tubenosed birds. Crustaceans feed on phytoplankton.
The number of zooplankton has two peaks during the year. The first is associated with the rise of overwintered species and is observed in surface waters. The second peak is characterized by the abundance of zooplankton throughout the entire thickness and is due to the emergence of a new generation. Both peaks appear in the form of two latitudinal bands of zooplankton concentration. This is the period of the zooplankton bloom in summer, when most of the zooplankton enters the upper layers and moves north, where a noticeable accumulation occurs in the Antarctic Convergence Zone.
In winter, condensation is observed in the divergence area, where individuals from the deep gather. In winter, the maximum species abundance was noted at depths of 250-1000 m.
The question of the vertical distribution of zooplankton is complicated by the ability of many organisms to perform regular (daily, seasonal) migrations from one zone to another.
Phytobenthos and zoobenthos in the waters of the Southern Ocean amazes with its richness and diversity. The number of phytobenthos decreases from South America to Antarctica. If 300 species are known, in Kerguelen - 138, then off the coast of Antarctica there are from 20 to 40 species. Mainly predominate various types red algae. Brown algae reach gigantic sizes (Marcocystis - 80 and sometimes 90 m in length) with limited biomass.
Among the representatives of zoobenthos, filter feeders predominate, mainly sponges (300 species), polychaetes (300), bryozoans (320), brachiopods (15), mollusks (300), and echinoderms (320 species).
The biomass of zoobenthos in coastal areas averages up to 0.5 kg/m2, and in some places reaches 3 kg/m2 at depths of 20-50 m; there are no permanent inhabitants in the surface zone. The fauna is distributed unevenly along the coast. The decrease in biomass begins at a depth of 500 m. It should be noted that if in other areas of the World Ocean the lower boundary of the sublittoral is at a depth of 200 m, then near Antarctica sublittoral animals live at depths of 500-700 m. The greatest species diversity is characteristic to a depth of 200-300 m , fish - at depths of 200-500 m.
The Antarctic region of the Southern Ocean has a rich, unique fauna and many endemic species. The fauna is characterized by gigantism of many representatives (for example, among sponges).
Near the Kerguelen Island, the fauna is 5 times poorer than mainland areas. There are about 100 species of fish in the Southern Ocean. Among them, only 12 are bottom-dwelling, belonging to the nototenaceae family, and of commercial importance. White pike, grenadier, gray and marbled notothenia, and southern blue whiting are widely represented in the Antarctic sector. In the Indian sector of the ocean, the number of commercial fish is small. It is home to striped whitefish (icefish), gray and marbled notothenia. In the Pacific sector, the largest in area, southern blue whiting and New Zealand macroruno are found.
Mammals. The total number of whales in the Southern Ocean is estimated to be approximately over 500 thousand. Pinnipeds include the crabeater seal, leopard seal, southern elephant seal, Ross seal, Weddell seal and a number of others. Antarctic seals make up up to 56% of the global pinniped population.
Ornithofauna. It is represented by 44 species of birds with a total number of 200 million individuals. Among them, 7 species of penguins account for 90% of the total biomass.
The Southern Ocean is considered the youngest on the planet. It is located in the Southern Hemisphere and neighbors other oceans. The waters of the Southern Ocean wash only one continent - Antarctica.
History of the discovery of the Southern Ocean
Interest in the Southern Ocean arose a long time ago. They first tried to explore it in the 18th century, but travelers were stopped by large accumulations of ice - the technology of that time did not allow them to overcome this obstacle. But it appeared on the map even earlier, in 1650.
English and Norwegian whalers visited polar Antarctica in the 19th century, and in the 20th century the Southern Ocean became a place for whaling and scientific research. The International Geographical Organization identified the Southern Ocean in 2000, combining the waters of the southern regions of the Atlantic, Pacific and Indian Oceans into one. And although the Southern Ocean has only conditional boundaries (this is due to the fact that there are no islands or continents in its southern part), its existence has long been proven, although the decision of the hydrological organization has never been legitimized.
Characteristics of the Southern Ocean
The Southern Ocean covers an area of more than 20 million square meters. m. In the south it borders on the coast of the southern polar continent; in the west and east it does not have clearly defined boundaries. The most deep place ocean - South Sandwich Trench (Meteor Trench). Its maximum depth is 8428 m, and the average depth is 3503 m. Near the shores of Antarctica, 14 marginal seas that are part of the ocean are identified: Somov, D'Urville, Mawson, Commonwealth, Cosmonauts, King Haakon VII, Riiser-Larsen, Lazarev, Davis, Amundsen , Ross, Bellingshausen, Scotch and Weddell.
The main feature of the Southern Ocean is the change in its conventional geographical boundaries in time and space due to interseasonal and interannual changes in the position of the Antarctic convergence lines. Another feature of the ocean is large number icebergs (scientists record more than 200 thousand annually).
Southern Ocean Climate
The Southern Ocean coast is an area where harsh elements reign. Above water, the climate is predominantly maritime, while on the shore it is closer to Antarctic. It is cloudy, windy and cold throughout the year. Snow falls in any season.
Closer to the Arctic Circle, the most powerful winds on the planet are formed. Big difference temperatures favor frequent storms. In winter, temperatures can drop to 65 degrees below zero. Scientists classify the atmosphere over the Southern Ocean as environmentally friendly.
Such weather conditions are due to a number of factors: the close location of Antarctica, the absence of warm currents, and the constant presence of ice cover. A zone is constantly formed over land high blood pressure, and around it there is a zone of low pressure.
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