What are the characteristics of the Atlantic Ocean?

Geographically, the Atlantic Ocean lies between Europe, Africa, North America and South America. The Atlantic Ocean borders the Arctic Ocean in the north, Antarctica in the south, the Pacific Ocean in the southwest and the Indian Ocean in the southeast. The Atlantic Ocean includes 943 14000 square kilometers, excluding 86557000 square kilometers. The volume including the sea is 3327 1 000 cubic kilometers, and the volume excluding the sea is 323369,000 cubic kilometers; The average depth of the sea is 3575.4 meters, which is not as good as that of the Pacific Ocean and the Indian Ocean, and the average depth of the sea is 3735.9 meters. At present, the known maximum depth of the Atlantic Ocean is 92 18m.

The word "Atlantic" in English comes from Greek, which means the sea of Atlas, the great god in Greek mythology. In Latin, the Atlantic Ocean is called Mare Atlantis, and the Latin form of Greek is Atlantis. It originally refers to the Mediterranean Sea between the Strait of Gibraltar and the Canary Islands, and later refers to the whole sea area. According to some Latin documents, the Atlantic Ocean is also called oceanus West, which means the ocean of the west.

In ancient times, knowledge about the Atlantic Ocean was recorded on Ptolemy's map. From 1440 to 1540, the land boundaries of almost all islands and oceans in the Atlantic Ocean are basically clearly drawn. During1819 ~1821year, the Antarctic continent and its surrounding islands were discovered. 1770, B. Franklin's map of the North Atlantic Ocean current (mainly describing the path of the Gulf Stream) was printed. At this time, the islands, land boundaries and current maps of the Atlantic Ocean have been determined.

Since19th century, human beings have entered the stage of marine investigation and research. Among the surveys organized by various countries, the British Challenger (1872 ~ 1876) and Discovery (1925 ~ 1927 and 1929 ~ 1938) are more important. German "Antelope" (1874 ~ 1876) and "Meteor" (1925 ~ 1927) and the investigation of the Gulf Stream by the US Coast and Geodesy Bureau. These oceanographic surveys play an important role in the study of the Atlantic Ocean.

Since 1970s, in order to know more about the Atlantic Ocean, people began to conduct joint research and experiments. For example, people have carried out special investigations and field experiments on the Atlantic Ocean, such as the joint study of air-sea interaction, the dynamic experiment of polygon-middle ocean, the tropical Atlantic experiment of the global atmospheric research program and the Famus program. Since then, people have learned more about the Atlantic Ocean.

In the natural environment of the Atlantic Ocean, a large continental shelf is one of the topographical features of the Atlantic Ocean floor. Mainly distributed in the coastal areas of Europe and North America. In addition, the natural environment of the Atlantic also includes climate characteristics.

The Atlantic Ocean lies between Europe, Africa and South, North America and Antarctica. In the north, Iceland-Faroe Ridge and Wavell-Thomson Ridge are bordered by the Arctic Ocean, and in the south, Antarctica is connected with the waters of the Pacific Ocean and the South Indian Ocean. The southwest is bounded by the meridian passing through Cape Horn, the southernmost tip of South America, and the southeast is bounded by the meridian passing through Cape Agus, South Africa, which is connected with the Indian Ocean. The west is connected with the Pacific Ocean through the Panama Canal between North and South America; The Strait of Gibraltar crosses the Mediterranean Sea in east longitude, and the Suez Canal is connected with the Red Sea.

On the whole, the ocean is long and narrow from east to west, extending from north to south, with a slightly S-shaped outline, with a total length of about 6,543.8+0.6 million kilometers from north to south. The Atlantic Ocean is in the equatorial region, with the narrowest width and the shortest distance of only over 2,400 kilometers.

The coastlines on the east and west sides of the Atlantic Ocean are roughly parallel. The southern coastline is straight, with few inland sea and bays; The northern coastline is tortuous, and there are many coastal islands, bays, inland seas and marginal seas. Islands and archipelagos are mainly distributed on the continental margin, mostly mainland islands. Therefore, there are fewer islands in the open ocean of the Atlantic Ocean.

The Atlantic Ocean flows into the Haihe River Basin, the largest among several oceans, with a basin area of 47.423 million square kilometers. The main rivers are St. Lawrence River, Mississippi River, Orinoco River, Amazon River, parana river River, Congo River (Zaire River), Niger River, Loire River, Rhine River, Elbe River and Nile River flowing into the Mediterranean Sea. It can be seen that the area where the Atlantic Ocean enters the Haihe River basin is relatively extensive.

Judging from the wind direction, ocean current, temperature and other aspects of the Atlantic Ocean, it is usually 5 north latitude as the dividing line between the South and North Atlantic Oceans. In addition, the land boundary in the northern hemisphere of the Atlantic Ocean is much longer than that in the southern hemisphere, and the coast is tortuous, many of which belong to oceans and bays.

submarine topography

The average depth of the Atlantic Ocean is 3300 meters, and the deepest part is the Puerto Rico Trench, 8380 meters. The outstanding feature of the ocean floor landform is that there is a S-shaped ridge with a width of 16 10 km, which is called the mid-Atlantic ridge and is a part of the global ridge (72450 km). The average depth of the basins on both sides of the mid-ridge is between 4200m and 6300m. In the North Atlantic, there are North Asia-America-Canada Basin, Guyana Basin (west), Canary Basin and Cape Verde Basin (east). There are Brazil basin, argentine basin basin (west), Angolan basin and Cape of Good Hope basin (east) in the South Atlantic. These basins fully illustrate the submarine topography of the Atlantic Ocean.

The relatively large continental shelf area is one of the topographical features of the Atlantic Ocean, mainly distributed along the coasts of Europe and North America. 80.2% is in the deep water area above 2000 meters,1.1.0% is in the water area between 200 and 2000 meters, and the continental shelf accounts for 8.7%, which is larger than the Pacific Ocean and the Indian Ocean. The second feature of the submarine topography of the Atlantic Ocean is that there is a mid-Atlantic ridge extending about 15000 km from Iceland to Bouvet Island from north to south in the middle of the ocean floor, which is cut off by a narrow water saddle in the equatorial region, generally about 3000 meters away from the water surface, and partially protrudes from the water surface to form a series of islands. It can be seen that the whole ridge is S-shaped, which divides the Atlantic Ocean into two deep-water basins extending parallel to the ridge.

From the east and west basins, the East China Sea basin is shallower than the West Sea basin, and the depth is generally less than 6000 meters. As we know, the Xihai Basin is very deep, and most of its deep-sea trenches are in the Xihai Basin. In the southern hemisphere, the main body of the mid-Atlantic ridge extends eastward and westward, and there are many lateral ridge branches, such as Walvis Ridge on the southwest coast of Africa and Rio Grande Ridge on the east coast of South America. At the southern end of the mid-Atlantic ridge, south of Bouvet Island is an area with a water depth of 5000 meters, which is called the Atlantic-Indian Ocean Basin. The deepest place in the South Atlantic is the South Sandwich Trench, with a depth of 8428 meters. However, at the northern end of the mid-Atlantic ridge, the seabed gradually rises upwards, and the depth of seawater between Greenland, Iceland, Faroe Islands and shetland islands is less than 600 meters. There are many underwater shoals in the eastern Atlantic Ocean, especially in the tropical and subtropical regions of the northern hemisphere.

Because the Atlantic Ocean extends from north to south and the equator passes through the middle, the climate is symmetrical from north to south and the climate zone is complete, which is a remarkable climate feature of the Atlantic Ocean. At the same time, influenced by ocean currents, atmospheric circulation, land and ocean contours and other factors, the climate in different sea areas is different. The equatorial belt of the Atlantic belongs to the convergence zone of the low pressure belt and the north-south trade winds. The wind in this area is weak and the direction is uncertain, so it is called windless zone.

Atlantic climate characteristics

Because the equatorial belt of the Atlantic Ocean is a low-pressure belt with strong updraft, convective cloud precipitation often occurs. The annual precipitation in this area is as high as 2000 mm, which is a rainy zone in the Atlantic Ocean. The subtropical zone is a high-pressure area, where the airflow is mainly subsiding and diverging, with less clouds and rain, sunny weather and strong evaporation. The general precipitation is 500 ~1000 mm. In the center of the Atlantic high, that is, the sea area near the Azores in the eastern ocean, the annual precipitation is only 100 ~ 250 mm, which is far less than the evaporation, so this area is a dry zone of the Atlantic Ocean.

The airflow sinking from the subtropical high to the equatorial low is called the trade wind zone. The northern hemisphere is the northeast trade wind, and the southern hemisphere is the southeast trade wind. The trade winds are stable and strong (3 ~ 4), which has become an important wind belt in the Atlantic Ocean and the driving force for the formation and maintenance of ocean surface currents. The airflow sinking from subtropical high to subtropical low is called prevailing westerly belt, which is a powerful planetary wind belt at middle and high latitudes and the driving force for the formation of west wind drift at 40 ~ 60 degrees north and south latitudes. In addition, westerlies often merge with cold air from the polar regions to form fronts and cyclones. Under the action of this front and cyclone, it will produce changeable weather and more precipitation, especially in winter, which will often bring snowstorms, causing strong winds and waves in high-latitude waters, seriously affecting shipping, offshore fisheries and oil industry production. The high latitude sea area north of 60 in the northern hemisphere (mainly in the east) is affected by warm current and cyclone, and the annual precipitation can reach about 1000 mm; On the contrary, in the sea area south of 60 in the southern hemisphere, due to the influence of dry cold air, there is no warm current, and the precipitation is very small, generally100 ~ 250 mm.

The temperature distribution in the Atlantic Ocean and the Pacific Ocean is basically similar, extending along the latitude direction and decreasing from the equatorial region to the high latitude. The equatorial region has the highest temperature. The annual average temperature is 25 ~ 26℃, and the annual change of temperature is very small (generally not more than 3℃). Near 20 north latitude and 20 south latitude, the temperature in the hottest month is about 25℃, and that in Leng Yue is about 20℃. Near 40 north latitude, due to the influence of warm current, the temperature in the North Atlantic is higher than that in the South Atlantic, with the hottest month of 20℃, the South Atlantic is only 15℃, and Leng Yue is 13℃ and 10℃ respectively. Near latitude 60, the warming effect of the North Atlantic warm current is more obvious, with the hottest monthly temperatures reaching 10℃, South Atlantic 0℃, Leng Yue 0℃ and-10℃ respectively. Therefore, the temperature in the North Atlantic is higher than that in the South Atlantic.

At the same time, due to the different effects of cold and warm air currents on the east and west coasts of the Atlantic Ocean, the temperature in the West Sea between 30 north and south latitudes is about 5℃ higher than that in the east. The sea temperature in the east north of latitude 30 is about 5 ~ 10℃ higher than that in the west, while in the south of latitude 30, the sea area is widened due to the narrowing of land and the influence of west wind drift. So the temperature difference between the east and the west of the Atlantic Ocean is not too obvious.

There are great differences between the north and the south of the Atlantic Ocean, and there are also differences between the east and the west. The annual temperature is not high, which is below 1℃ in equatorial region, below 5℃ in subtropical region, below 10℃ in northern latitude and below 60℃ in southern latitude, only exceeding 25℃ in the northwest and southernmost part of the ocean. Northeastern trade winds prevail in the northern part of the Atlantic Ocean and southeast trade winds prevail in the southern part. The temperate zonal belt is located in the transition zone between cold and warm airflow and westerly belt, and the wind force is the largest. Therefore, there are many storms between 40 degrees and 60 degrees north and south latitude, and there are often hurricanes in tropical latitudes of the northern hemisphere from May to 10. The precipitation in the Atlantic Ocean is 500 ~ 1000 mm at high latitudes, 1000 ~ 1500 mm at mid latitudes,1000 mm from east to west in subtropical and tropical regions, and over 2000 mm in equatorial regions. The average sea surface temperature near the equator of the Atlantic Ocean is about 25 ~ 27℃, and it is colder in the east than in the west between 30 north and south latitude, but the opposite is true to the north of 30 north latitude. Therefore, in the Atlantic Ocean, the summer ice floes in the southern hemisphere and the northern hemisphere can reach about 40 degrees north and south latitude respectively.

There is little change in the annual temperature in the Atlantic Ocean, and the annual temperature difference in the equatorial region is less than 65438 0℃. In addition, the annual temperature difference is 5℃ in the subtropical region and 10℃ in the mid-latitude region, but only exceeds 20℃ in the northwest and southernmost region. The average temperature of seawater is 65438 07℃, which is slightly lower than that of the Pacific Ocean. The salinity of the Atlantic Ocean is higher than that of the Pacific Ocean, with an average of 35.4.

In the north Atlantic, the subtropical high lies between north latitude 15 ~ 30, and the northeast trade wind lies in the south. The main westerlies lie between 40 and 60 degrees north latitude. In the South Atlantic, the tropical high pressure zone is located near 30 south latitude, and the prevailing westerly belt extends almost from 40 south latitude to Antarctica. In the Atlantic Ocean with latitude of 5 ~ 20 from north to south, there are more than 7 10 months of hurricanes every year. There is often sea fog along the coast of Newfoundland in summer; In winter, the Atlantic coast of Europe is foggy; The southwest coast of Africa is foggy all the year round. It can be seen that the Atlantic ocean current forms a north-south circulation.

The circulation in the northern Atlantic Ocean is mainly composed of the North Equatorial Warm Current, the Gulf Warm Current and the Canary Cold Current. The southern circulation warms from the southern equator. Brazil Warm Current, west wind drift and Benjira Current. In addition, because the Gulf Stream is the strongest warm current in the Atlantic Ocean, it plays an obvious role in climate regulation in northwest Europe.

The Atlantic Ocean is rich in marine resources, mainly mineral resources and aquatic resources that can be used by people. The Atlantic Ocean is the second largest ocean in the world, and it is also rich in marine resources.

ocean resources

In the Atlantic Ocean, the main mineral resources are oil, natural gas, coal, iron, heavy sand and manganese nodules. There are two oil and gas areas in the basins on both sides of the Atlantic Ocean, namely the East Atlantic and the West Atlantic.

The West Atlantic oil and gas belt in the Atlantic mainly includes the following contents:

1. Venezuela has two oil fields, namely, the submarine oil field of Lake Maracaibo and the Gulf of Paria oil field between Trinidad. The proven reserves are 4.02 billion tons and the natural gas is 862.4 billion cubic meters. In recent years, the annual output of oil fields is nearly 654.38 billion tons, and the natural gas reaches 5 billion cubic meters.

2. Offshore oil fields in the Gulf of Mexico. The oilfield is mainly distributed in bay of campeche in the southwest and along the coasts of Texas and Louisiana in the United States. According to relevant personnel, bay of campeche has nearly 5 billion tons of oil reserves (1978), while the United States has 2 billion tons of oil reserves and 360 billion cubic meters of natural gas reserves in the continental shelf area of the Gulf of Mexico.

The East Atlantic oil and gas belt in the Atlantic Ocean includes the following areas:

1. Beihai continental shelf oilfield, with proven oil reserves of over 4 billion tons and natural gas of 3 trillion cubic meters (1977). In recent years, the annual output of oil has reached over 654.38 billion tons, and the annual output of natural gas is nearly 654.38 billion cubic meters. The exploitation of Beihai Oilfield has greatly improved the energy conditions of Nordic countries. However, there are many storms and rainy days in the North Sea in autumn and winter, which brings great difficulties to offshore drilling and exploitation and increases the cost of oil production.

2. The offshore oil area in the Gulf of Guinea is mainly Nigeria, with proven oil reserves of about 2.6 billion tons. In addition, oil and gas resources have also been found in the offshore continental shelf of Canada, Brazil and Argentina on the west coast of the Atlantic Ocean. At the same time, some offshore oil fields have been put into production.

Seabed coal is also an important marine resource in the Atlantic Ocean. Seabed coal is mainly distributed in the offshore of Scotland in northeast England and the continental shelf outside Nova Scotia Peninsula in Canada. Britain's seabed coal reserves are not less than 550 million tons, and the annual coal mining capacity is 20-25 million tons. In addition, coal deposits have also been found in the coastal seabed of Spain, Turkey, Bulgaria, Italy and other countries. On the east side of Newfoundland Island in North America and Canada, the world's largest submarine iron ore was discovered, with an estimated reserve of more than 2 billion tons, which has been mined. There are also submarine iron mines in the Baltic Sea and the Gulf of Finland. There are also a large number of sand mines in the Atlantic Ocean, which are distributed along the coasts of the United States, Brazil, Argentina, Norway, Denmark, Spain, Portugal and Senegal. Manganese nodules are widely distributed at the depth of 4000 ~ 5000 meters in the Atlantic Ocean, with a total reserve of about 65.438+0 trillion tons, mainly distributed in the North American basin and the bottom of argentine basin. The richness and grade of mineral resources in the Atlantic Ocean are not comparable to those in the Pacific Ocean and Indian Ocean.

In addition, the Atlantic Ocean is rich in biological resources, the most important of which is fish. The catch of Atlantic fish accounts for about 90% of the catch of Atlantic marine life. The catch of the Atlantic Ocean once ranked first in the world's oceans. After the 1960 s, it was lower than the Pacific Ocean and relegated to the second place. However, in terms of unit area, its catch reached 250kg/km2, still ranking first in the world. Among them, the largest catch is in the northeast sea, that is, around the North Sea, the Norwegian Sea and Iceland. The annual catch accounts for about 45% of the total catch in the Atlantic Ocean, the average output per unit area is 830 kg/km2, and the continental shelf area is about 1.200 kg/km2. Followed by the northwest Atlantic, the catch accounts for 20% of the total catch, and the average catch per unit area is 690 kg/km2. In the continental shelf waters east of Newfoundland, the United States and Canada, it is the single fishery with the highest yield in the world's oceans, with an average yield per unit area of1.500kg/km2.

In addition, the coastal areas of the Caribbean, the Bay of Biscay, Angola and Namibia are also important fishing areas. The Atlantic Ocean near Antarctica is an important fishing area for krill and whales. The main fish caught in the Atlantic Ocean are herring, northern cod, hairscales, long-tailed cod, flounder, tuna, salmon, horse sole, sea bass and so on. These fish are mainly distributed in the continental shelf and the continental shelf area near the island. In open waters, especially tropical waters, there are sail fish and flying fish. The coastal areas of western Europe and North America are rich in oysters, mussels, sea fans, crayfish and crabs. At present, some countries along the Atlantic coast are actively developing artificial breeding of mollusks such as mussels and sand mites.

In the Atlantic Ocean, biota form five water layers from the ocean surface to the seabed:

1. Coastal benthic zone, the maximum depth of which is within 60m, including all kinds of coastal animals and most algae;

2. Bright zone, the maximum depth of which is within180m, belongs to the part where sunlight can shine, and the creatures inhabiting this zone include a large number of zooplankton and plants, which provide 90% nutrients in the ocean;

3. The middle-deep layer, with a depth of 200-900 meters, is the living area of sperm whales and squid;

4. Deep sea area, with a depth of 900-4000m, is a dark area and a habitat for luminous animals;

5. Benthic zone, the depth of which is below 4000m, is inhabited by primitive animals.

fishery

The Atlantic Ocean is also rich in fishery resources, with Newfoundland and the North Sea in the northwest and northeast as the main fishing grounds, rich in herring, cod, sardines, mackerel, hairscales and so on. , as well as oysters, mussels, crayfish, crabs and various algae. The marine catch accounts for about 1/3 ~ 2/5 of the world. In addition, there are a large number of whales, seals and krill near the Antarctic continent, and the catch of marine animals is also quite large.

The fishing grounds in the Atlantic Ocean account for more than half of the world. High-yield areas are mainly in the coastal areas of North and South America. On the coast of Newfoundland, where the Gulf Stream meets the Labrador Current, it is the richest fishing ground in the world. Overfishing in the second half of the 20th century led to the shortage of fish in several traditional fishing grounds, especially in the North Atlantic. As a result, the fishing industry in the Atlantic has also been seriously damaged.

The Atlantic Ocean plays an extremely important role in world shipping. It connects the Panama Canal and the Pacific Ocean in the west, the Strait of Gibraltar in the east, the Suez Canal and the Indian Ocean in the Mediterranean Sea in the north, and the Arctic Ocean and Antarctic waters in the south, with convenient air routes extending in all directions. At the same time, the Atlantic coast is almost all the most developed regions on all continents and capitalist countries with high economic level, with frequent trade and economic exchanges. Therefore, the Atlantic Ocean plays an important role in the global shipping system.