Knowledge Title: Arctic ocean

Other Title: Arctic Ocean

Knowledge Content:

    The world's smallest and coldest ocean. Located at the northernmost tip of the earth, largeto the Arctic as its center, the Arctic Circle is the ocean surrounded by the northern coasts of Asia, Europe and North America. The foreign name Arctic is derived from the Greek language, meaning the ocean facing the constellation of The Big Bear. With an area of 1,478.8 million square kilometres, it is 1/14 of the Pacific Ocean, 1/7 of the Atlantic Ocean and 1/6 of the Indian Ocean, accounting for 4.1% of the world's ocean area. The average depth of the Arctic Ocean is 1,225 meters, one-third of the Pacific Ocean, and the maximum depth is 5,527 meters, less than 1/2 of the Pacific Ocean. More than two-thirds of its area belongs to the underwater edge of the continent, i.e. it has a very wide continental shelf around the Arctic Ocean.

    The Arctic coastline is very tortuous, forming many shallow and wide edge sea and bay. Coastal types include erosion coasts, fjord-style coasts, delta coasts and lagoon-type coasts. The banks of the Asian mainland include the Barents Sea, the Kara Sea, the Laptev Sea, the East Siberian Sea and the Chukchi Sea. Along the coast of North America is the Beaufort Sea and the Greenland Sea. The Arctic Ocean has many islands, second only to the Pacific Ocean. The total area of the island is about 3.8 million square kilometers, all of which are continental islands, mostly located on the continental shelf. The main rivers flowing into the Arctic Ocean are the Obi, Yenisei, Renae and Maer. On the edge of the Arctic Ocean, there are countless icebergs, not as high as antarctic icebergs, but strange shape. Icebergs drift south along the sea, some from the Arctic to the North Atlantic. Because the rafting route is not fixed, it causes great harm to ships sailing in the North Atlantic.

    Due to the cold climate and ice cover, the Arctic Survey was small, and it was not until the 1930s that floating science stations were set up on the ice to conduct some more systematic expeditions. In 1937, the Soviet Union landed in the Arctic by ice plane and established the Arctic 1 Floating Science Station in the Arctic Ocean. In the 1940s, the United States, Canada and other countries made 20 polar ice landings from the air, and built 8 marine stations and 1 scientific station. During the International Geophysical Year (1957-1958), in addition to flight activities, many continuous observational floating stations were added and nuclear-powered submarines were used to examine the situation under the ice sheet.

    The Arctic Ocean has a broad continental shelf along the coast of the Eurasian continent, and in the Arctic, Norwegian and Greenland sea floors, there are a series of ridges and seafloor bulging, which are interlaced with the basins and troughs (sea troughs). There are sedimentary layers on the ocean floor.

    Continental Shelf The bottom area of the Arctic Ocean is more than half (50.3 per cent) occupied by the continental shelf. The continental shelf near the Russian coast is the most fully developed, with a width of 1300 to 1500 km, and is the largest continental shelf area in the world's oceans. The continental shelf is out of the water, forming a continental island. Mainly: Arctic Islands, New Land Islands, Spitsbergen Islands, Northern Islands, Novosibirsk Islands and The Frans Joseph Istin Islands.

    There are 3 ridges at the bottom of the Arctic Ocean, namely the Lomonosov Ridge, the Mendelev Ridge and the Nansen Ridge. (1) The Lomonosov Ridge is located in the central part of the Arctic Ocean, roughly from Russia's Novosibirsk Islands, passing through the Arctic along the 140-degree line east of the Island of Elsmir in the Canadian Arctic Archipelago. About 1800 kilometers long, 60 to 200 kilometers wide, 3300 to 3700 meters above the bottom of the ocean, ridges generally 900 to 1650 meters from the ocean surface. The Lomonosov Ridge, though volcanic, is not a mid-ocean ridge, but may be a pleated mountain range that has been complicated by tectonic fractures along the meridian. Because of this ridge barrier, there are obvious differences in ocean currents, water temperature and salinity in the east and west of the Arctic Ocean. (2) Mendeleev Ridge, also known as the Alpha Sea Range, is parallel to the Lomonosov Ridge. It starts on The Island of Flangel and extends to the vicinity of Ellesmere Island. The mountain is relatively small in height, with lighter cutting and a gentle slope. (3) Nansen Ridge, also known as The Gakley Ridge, is the middle ridge of the Arctic Ocean. It starts near the mouth of the Renae River, extends north to the north of the Greenland Sea, then turns south and reaches the North Atlantic Ridge near Iceland. It is not more than 200 km wide and the highest point is about 1000 meters from the ocean surface.

    The three ridges mentioned above separate the Nordic waters of the Arctic Ocean into the Norwegian and Greenland basins, and the Arctic seas into the Nansen Basin, the Amundsen Basin (also known as the Fram Basin), the Makalov Basin and the Canadian Basin. The bottom of each basin is flat, with a depth of 3000 to 4000 meters, mostly due to earthquakes and crustal fractures. Among them, the Canadian basin is 1100 kilometers wide, the largest basin in the Arctic Ocean. At a depth of 3,850 meters, the bottom of the basin is mostly flat on the canadian deep plains, and the southern part of the basin has alluvial cones formed by the erosion of more rivers by horses. The Nansen basin has the largest depth, the north is mostly more than 4000 meters, the maximum depth is 5449 meters, the bottom of the basin is a flat deep-sea plain, the north surrounds the Nansen Ridge.

    The ocean floor is deposited in the Arctic Ocean, and only the most surface layer of the bottom sediment (up to 4 m thick) is studied. The uniqueness of sedimentation at the bottom of the Arctic Ocean is that (1) the sediments are very good land-based sediments and (2) the entire sediment layer is thicker than other oceans (1000-3500 m). The main distribution on the continental shelf is the sedimentation of sandy and powdered sand land sources, and there are not many impurities in biolime and silicon components. The role of glacier sediments is manifested in the imperfection of sediment sorting at the bottom and the presence of coarse inclusions in finer sediments. But there are a large number of secondary sedimentary residues. The deep water area of the Arctic Ocean can be divided into two types of sedimentation - deep water deposition and extreme deep water sedimentation.

    The sediment layer at the bottom of the paved basin is called extremely deep-water sedimentation. This is mainly a sort of soft mud, the glacier sent very little gravel inclusions. Manganese is found in most areas of deep-sea basins, so these sediments can be called low manganese deposition. Ferromanganese nodules have not been seen in deep water deposits. However, the presence of this TB on the continental shelf is significant.

    The climate and low water temperature sway the thriving development of calcium plankton and the strong dissolution of lime particles. The accumulation of diatom residues far exceeds the inflow of land-based material.

    Climate The Arctic Ocean is basically located in the Arctic Circle, the winter polar night is long, a large amount of heat dissipation, the summer polar days are long and the sun's height angle is small, and the need to consume a lot of heat energy to melt snow and sea water; The average temperature in most areas from November to April is -20 to -40 degrees Celsius, with only the Norwegian Sea and the Barents Sea affected by the North Atlantic warm current and temperate cyclones coming eastwards near low pressure in Iceland, with temperatures reaching around 0 degrees Celsius. There is no real summer in the Arctic Ocean, and even in the warmest months, temperatures are only 0 to 6 degrees Celsius.

    The Arctic Ocean is mainly controlled by polar high pressure, the air flow is sinking, storm weather is not much, but at its edge, due to the increase in air pressure gradient, often with the season,” and wind speed is quite large. During the winter, due to the influence of low pressure in Iceland and low pressure aleutian, cyclones are often formed in the northern coastal waters of the Asian-European continent and off the coast of northern Alaska.

    Annual precipitation in the Arctic Ocean is generally only 100 to 200 mm, and mainly snow. Even in the warmest July and August months, snow is often carried in the rain. Although the annual precipitation in the Arctic Ocean is small, but due to the weak evaporation, the low flat part of the island still suspects excessive water. In addition, affected by the underside of the ice sheet, over the Arctic Ocean, whenever July to August, often formed a low cloud, and foggy, visibility is very low.

    Marine Hydrology The surface of the Arctic Ocean is covered with sea ice. According to geographical location can be divided into shore ice, floating ice and Arctic ice clumps 3 categories. Shore ice and floating ice were mainly distributed in the northern shore of the Asian and European continent sewelters, the ice thickness is 0.5 to 1.5 meters and 0.8 to 1.8 meters, melting most of the summer. The Arctic ice clumps are located outside the shore ice belt and are interlaced with the floating ice of that year, with ice thickness of 2.5 to 4 meters. Arctic ice clumps are made up of huge ice cubes, which are often separated by cracks or ice caves. The surface of the general ice cube is flat or wave-like. Sometimes it becomes a messy group of ice because of the crowding of ice and ice. Without a strong icebreaker, shipping is difficult.

    Floating ice rafting is often dominated by prevailing winds and currents. In the Barents Sea and its adjacent waters, year-round by the North Atlantic warm currents, floating ice with the ocean currents in the direction of the anti-time needle circulation, but not closed circulation, floating ice drift first to the northeast, and then back to the southwest direction, incorporated into the east Greenland cold current. The east Greenland cold snap brings water and floes from the Arctic Ocean into the North Atlantic. It is estimated that this cold snap will take 10 cubic meters of ice from the Arctic Ocean each year. In the Pacific Ocean and the waters north of North America, they are often dominated by the cyclone circulation, so that floating ice flows more clockwise. In drifting ice, common high-burst icebergs doped in between. The icebergs were formed when glaciers from Greenland, the islands of northern Canada, some islands in northern Russia and islands such as Spitsbergen slipped into the sea. Icebergs often surface up to 10 to 12 meters, sinking into the sea is often as high as 50 to 60 meters.

    The Arctic Ocean is the main source of cold currents in the northern hemisphere ocean. The east-east Greenland cold snap and Labrador cold snap are the strongest. The east Greenland cold current flows from north to southwest along the east coast of Greenland, 175 to 200 km wide, with a flow rate of 2 million cubic meters per second at the exit, and a year-round water temperature of less than 0 degrees Celsius. The Labrador cold current originates in Baffin Bay and flows south along the east coast of the Labrador Peninsula, with a winter water temperature of -1C, 2C in summer and a flow rate of 3.4 to 5.4m/s, making it a major source of icebergs and floating ice in the North Atlantic.

    Marine resources Because most areas are covered by ice, especially most of the sea surface upper water temperature is below 0 degrees C year-round, hindering the proliferation of plankton, phytoplankton only 200 species. For this reason, there are far fewer species and quantities of fish that use plankton as bait than any other ocean. The Barents Sea fish and sea animals, which are only affected by the north Atlantic warm currents, are abundant. Fish include herring, cod, black-line cod, sea bass, mackerel, mackerel, mackerel, etc.; Salmon, white salmon and cucumber fish are often in the arctic Ocean, where large amounts of water are diluted by rivers, but not in large numbers. It is also home to Arctic-specific animals such as walruses, seals and polar bears, and Arctic foxes. But the numberhasing has fallen very quickly, thanks to the mass killings in recent years.

    Mineral resources are also abundant. Oil and gas in the Barents Sea, the Kera, The Beaufort Sea and the northern canadian islands and straits, particularly the northern coastal islands of Canada and its adjacent straits, are estimated to have oil reserves of 100 x 108 tons. Manganese nodules are also found on the bottom of the Arctic Ocean, mainly in the Barents Sea, the White Sea and the Kara Sea. The Barents Sea is an important fishing ground in the Arctic Ocean. The United States has been drilling for oil in the northern Gulf of Alaska.

    Although the Arctic Ocean is a short-cut way to communicate the Atlantic and Pacific Oceans and the three continents of Europe, Asia and North America, it is poorly exploited due to its remote location and harsh climate. Sea shipping, except for the southern part of the Barents Sea is generally unfrozen, often by passenger and cargo ships, the northern part of Russia and the northern edge of the United States, Canada, sea shipping is very difficult. Although the Soviet Union had opened up its northern route in the 1930s under Stalin, it was difficult to travel between Murmansk and Vladivostok, even in the warmest season, without a powerful icebreaker.

    The air transport over the Arctic Ocean is the shortest route for Japan and the Far East to North and Northern Europe and Western Europe. In 1957, the first air route from Tokyo, Japan, through Anchorage, Alaska, and the Arctic to Copenhagen, Denmark, reduced the original range of 1.56 x 104 kilometers by 2,700 kilometers. In 1969, the same route was opened from Tokyo and Osaka to Paris and London. In addition, There are also routes over the Arctic between Tokyo and San Francisco and New York.

    The strategic position of the Arctic Ocean is particularly important, having for many years been a front for the United States to compete with the Soviet Union. There are military bases along the Arctic coast, and from the ocean to the sea to the coast, are in contention. Important ports along the Arctic coast are Arkhangelsk, Murmansk (unfrozen port), Dixon, Dujinka, Pewick, Narvik (unfrozen port), Trondheim (unfrozen port), Tromso (unfrozen port), Hamerphster (unfrozen port) and so on.