The Baltic Sea is more than 1600 kilometers long, 190 kilometers wide on average, and covers an area of 420000square kilometre, totalWater storageUp to 23000cubic kilometers , YesearthLargest onBrackish waterIn the water area, the water depth is generally 70 – 100 meters, the average depth is 55 meters, and the deepest Gotland Trench is 459 meters deep.[1-2]
The Baltic Sea is the largest in the worldBrackish waterWaters.stayScandinaviaAndContinental Europebetween.From 54 ° north latitude to northeastarctic circleIt is more than 1600 kilometers long, 190 kilometers wide on average, and covers an area of 420000 square kilometers.[3]
The Baltic Sea is almost surrounded by land, and the whole sea surface is betweenSweden, Russia, Denmark, Germanypoland, Finland, Estonia, Latvia and Lithuania.It extends eastward into the Gulf of Finland between Finland and Estonia, Russia, and northward into the Gulf of Bothnia between Finland and Sweden.[1]
The west is connected to the North Sea through the Skagerrak Strait.To the east, the Kattegat Strait separates Denmark from Sweden.There are Bornholm Island, Oland Island, Gotland Island andOran(Aland) Islands.
Since the Tertiary, the Baltic Sea and its surrounding areas have experienced multiple alternations of land and water.The Baltic was the lastGlaciationAt the end, the glacier was formed after a large amount of melting.This makes the coastline of the Baltic Sea complex and diverse. The coastline is very tortuousLagoonThe north is dominated by high and steep rocky coast,Seafloor sedimentMainly sand, clay and glacierOoze。
The Baltic was at the end of the Ice AgeScandinaviaIce fieldA part of a vast ocean formed by dissolutionarcticThe sea is formed by receding and sinking of the ground.
The deepest part of the Baltic Sea isSwedenBetween the southeast coast and Gotland Island, the water depth exceeds 459 meters.There are many shallow ridges on the seabedSea basin。
The Baltic Sea is located inTemperate marine climatetowardsContinental climateIn the transition zone of, westerly winds prevail throughout the year, storms often occur in autumn and winter, and there is a lot of precipitation.Annual average in the northprecipitationAbout 500 mm, more than 600 mm in the south, and up to 1000 mm in some sea areas.It is located in middle and high latitudes, with less evaporation.Surrounding riversTotal runoffRich.
mist
Baltic Sea Region summercloudinessAbout 60%, and more than 80% in winter.The southern and central regions have an average of 59 foggy days every year,Gulf of BothniaThe north has the least fog, about 22 days a year.
ocean current
becauseNorth Atlantic Warm CurrentIt is difficult to enter the Baltic Sea, and the sea water cannot be regulated, resulting in low temperature in winter, andNorth South differencesIt is relatively large, the temperature in summer is not high, and the difference between north and south is small.
The water temperature rises from north to south, and the surface water temperature in August,Gulf of Bothnia9 ℃ – 13 ℃,Gulf of Finland15 ℃ – 17 ℃, 14 ℃ – 18 ℃ in the middle and 20 ℃ in the west.From February to March, the water temperature in the open sea area is 1 ℃ – 3 ℃,Gulf of Bothnia、Gulf of Finland、Riga BayAnd other bays are lower than 0 ℃.January from south to northAverage temperature1.1 ℃ – 10.3 ℃ below zero, and 17.5 ℃ – 15.6 ℃ in July.
During freezing
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Ice and snow
Taling Town on the Baltic Coast
The Baltic Sea is shallow and light, so it is easy to freeze.The northern and eastern sea areas usually have a period of ice cover that is not conducive to navigation every year. From the beginning of November every year, the northern part of the sea begins to freeze, and the areas covered by ice are different every year.General year,sea iceOnly in the bays.Only in severe winter can almost the whole sea area be covered with ice.The average thickness of sea ice is 65cm.The Gulf of Bothnia is icebound for 210 daysGulf of FinlandandStockholm185 days nearby,Riga BayIt lasts 80 – 90 days, and the coast of Poland and Germany is icebound for 30 – 40 days.
The southern Baltic Sea usually does not freeze, but Sweden andDenmarkThe straits between are sometimes icebound.It is also easy to form large ice packs in the north of Bothnia Bay, which sometimes can be as high as 15 meterssea transportAs a result, the ship could only dig a channel on the frozen sea and then slowly move forward.
The Baltic isNorthern EuropeAn important channel is also an important channel for trade between Russia and Europe, which is between coastal countries and to the North Sea andNorth AtlanticFromPeter the GreatSince then, the Baltic Sea has beenRussiaAn important export to Europe.Russia andIran, India and other countriesthe indian oceanandWestern EuropeThe planning of "North South Corridor" also takes the Baltic Sea as the northern terminal.[2]
The Baltic Sea is shallow and light, easy to freeze.Gulf of BothniaBottom andFinlandOn the coast, sometimes the ice is up to 15 meters high.stayOran IslandsAnd the eastern section of the Gulf of Finlandfloating iceIt is 91 cm thick.Except for the extremely cold winter,Stockholm、Turku(Turku) and Helsinki are navigable.
Since the early 1990s, the number of ships sailing in the Baltic Sea has increased sharply, and ships sailing in the Baltic Sea every yearMain channelThere are more than 40000 ships.The Baltic Sea has ferries connecting the major ports of coastal countries.And through the White Sea Baltic Sea River andWhite SeaIt is connected withVolga RiverConnect.
Important ports
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(From south to north,anti-clockwiseOrder, important ports in bold)[3]
The Baltic Sea pours a lot of fresh water from the surrounding rivers,Longest riverThey are Vistula River and Oder River.
The strong North Sea tide cannot reach the Baltic Sea, so the Baltic Sea lacks tidal current,Tidal waveIt's also very small.The water surface flows due to the storm, strongnortheasterly windIt leads to big waves on the south coast and high water level along the coast.And advantageousSouthwest windIt contributes to the accumulation of sand dunes along the German and Polish coasts, while raising the water level along the northern coast of the Baltic Sea.
The surface circulation of the Baltic Sea is cyclonic, from east to north along the southern coast, then south along the eastern coast of Sweden toOresund Strait, byOresund Straitflow out.The flow rate is about 5 cm/s – 20 cm/s.Under the action of strong wind, the flow direction and velocity in local sea area will change.
Great Belt Strait
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Sometimes it can reach more than 80 cm/s near the shore, and it can also increase to 30 cm/s in open waters.When the runoff into the sea is large, the surface layerWater channelThe Oresund Strait enters the North Sea.
The open sea water of the Baltic Sea flows from the deep part of the Great Belt Strait, first along the south coast to the east, and then along the east coast to the north, formingcounter-clockwise directionocean current.
Due to the movement of cyclonessea areaThe water level in the nearshore area ofgulfThe part close to the inland can reach 1.5 – 3 meters.In November 1824, the water level in Leningrad reached 4.1 meters.
The changing effect of the North Atlantic current is hardly felt in the Baltic Sea.
The reason why the Baltic Sea water is cold is that the salt content of the sea water here is only 1/4 of the salt content of other sea water, so it is easier to freeze.
One fifth of Europe's surface water flows into the Baltic Sea through more than 250 rivers, and a large amount of fresh water comes in. However, the Baltic Sea water is limited in water discharged into the North Sea through narrow channels, so the water in this sea is almost light.
Spring climate
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Scenery of the Baltic Sea
The long-term freezing in spring slows down the departure of the spring climate, while the slow expansion of surface freezing prolongs the autumn. Even when the Baltic Sea is navigable, due to frequent strong storms and sudden changes in wind power, sailing is also dangerous.
The Baltic Sea has the lowest salinity in the world, because the Baltic SeaFormation timeNot long, hereIce AgeAt the end, it was still a vast ocean submerged by ice water. Later, the glacier retreated northward, leaving the lowest valley to form the Baltic Sea. The water quality was already good;Secondly, the Baltic Sea area is blocked, and the channel with the open sea is shallow and narrow, so it is difficult for the seawater with high salinity to enter;In addition, the Baltic Sea has high latitude, low temperature and weak evaporation;Here againWesterliesThe climate is humid and there is much rain aroundVistula River 、Oder River、Neman River、Wiener River, West GermanyandNeva River250 rivers of equal size are injected, with annual averageRiver runoffIt is 437 cubic kilometers, which is about 4 times of the Baltic Sea's freshwater catchment area.
Salinity of seawater
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So the water in the Baltic Sea is very thin.seawaterSalinityOnly 0.7% – 0.8%, the highest recorded salinity of the sea surface is 1.0%, and the seabed is 1.5%, which is much lower than the average salinity of the world's sea water (3.5%).
The salinity of the Baltic Sea gradually decreases from the outlet to the sea,Great Belt StraitandLittle Belt ChannelThe salinity of seawater is 15 ‰, 8 ‰ – 11 ‰ in the west,Moon Island8 ‰ in the east, 6 ‰ – 8 ‰ in the middle,Gulf of Finland3 ‰ – 6 ‰ (only 2 ‰ near inland),Gulf of BothniaGenerally, it is 4 ‰ – 5 ‰ (the northernmost part is 2 ‰).The salinity of deep layer and near bottom layer is 16 ‰ in the west, 12 ‰ – 13 ‰ in the middle and about 10 ‰ in the north.When inflowAtlanticWhen the sea water increases, the salinity in the west can increase to 20 ‰.Deep Baltic SeaSeawater salinityHigh, due to high salinitythe north seaCaused by seawater inflow.
Economic culture
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Wood andFish isThe main commodity of the Baltic Sea.Finland, Sweden and RussiacorkIt is a large source of goods for export;wood processing (e.gpapermaking, fiber making andFiberboard）It is increasingly important economically.Iron ore in Sweden, shipbuilding and marine machinery in Finland and Denmark, Swedengothenburg (Goteborg）Both automobile manufacturing and light machinery are important industries along the coast.The main marine products area sole、Codfishandherring。
Smoked or pickled herring is an important traditionExport products。Produced outside Falster, DenmarkOysters、Crayfishandprawn。Large coastal cities include Copenhagen, Stockholm, Helsinki, St. Petersburg (Leningrad)Tallinn(Tallinn), Riga, KielGdansk(Gdansk) andShicheqing(Szczecin)。
Russia's pipeline "Beiliu" to transport natural gas to Germany via the Baltic Sea will be completed in 2012.Russia also plans to expand the Baltic port of Usti Luga.[4]
environmental protection
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The development of industry and shipping not only makes the strategic position of the Baltic Sea more and more important, but also makes the Baltic Sea suffer more and more serious pollution.
In 2007, an expert report of the Helsinki Commission in the Baltic region pointed out thatheating rate It is higher than the global average level, which has affected the fishery in this area and prolonged the crop growth season.The study points out that the warming rate in this region has been higher than the global average. In this centuryAnnual average temperatureIt will increase by 3 – 5 ℃.
frontSoviet UnionThe pollution left by the Baltic Sea has already beenMarine organismOfhabitatCaused great damage, andClimate warmingEven worse.In addition, the increase in temperature may bring more precipitation, reduce the salt content of the Baltic Sea, and continue to destroymarine organismLiving environment.The heating rate in the northern region will probably be higher than the global average, because the dark soil and water distributed in the north absorb much more heat than the reflective ice and snow.Warming could also prolong the growing season in the Baltic region.
Haiti temperature
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By the end of the 21st century, the temperature in the Baltic Sea region will increase by 3 ℃ – 5 ℃, extending the growth season in the northern region by 20 – 50 days, and in the southern region by 30 – 90 days, which will be conducive to the growth of crops and forests.
The ice age of the Baltic Sea will be greatly shortened, and the northern region will be shortened by 1 – 2 months,Central region2 – 3 months shorter.In the Baltic Sea, a considerable number of passing ships leak or discharge into the sea every yearWaste oilThe Baltic Sea is suffering from more and more serious pollution. Every year, as many as 150000 seabirds are killed by oil pollution.
The researchers passed a survey on the coast 50 kilometers south of Gotland Island in the Baltic SeaEnvironmental surveyIt is found that about 20000 seabirds are killed by oil pollution here every year.It can be inferred that about 150000 of the millions of seabirds wintering in the Baltic Sea each year are killed by oil pollution.In addition, the Baltic coastGrey sealThe living condition has also been seriously threatened by the pollution of the surrounding environment, and many grey seals are affected by diseases such as intestinal ulceration.There are about 10000 gray seals in the Baltic Sea. In 1900, the number of gray seals here was about 100000.Researchers pointed out that the economic activities that caused the pollution of the Baltic Sea were closely related to politics. However, due to the massive hunting of seals by humans in the 20th century and the infertility of female seals caused by pollution, the number of seals had dropped to 3000 by the 1980s.[4]
The Baltic Sea, located between Northern Europe and Central Europe, has become the most polluted sea in the world, according to the website of Lianhe Daily.European political and business leaders and non-governmental organizations gathered in Helsinki, the capital of Finland, on the 10th to hold the "Baltic Sea Action Summit" (BSAS) to discuss how to restore its clean face.The participants of this summit will discuss these two plans with the Russian side to ensure that they will not affect the ecological environment of the Baltic Sea.[4]
European countries attach great importance to this summit. Prime Minister Putin of Russia, King Gustav of Sweden, politicians from Latvia, Lithuania and other countries attended the meeting in person.Finnish President Tarja Halonen delivered a speech at the opening ceremony of the meeting on the 10th, calling on all countries to unite and take immediate action to save the Baltic Sea.Halonen pointed out: "We don't expect miracles, but if all people can seriously do it, maybe miracles will happen.".[4]
In the 1970s, due to thePolychlorinated biphenylsThe number of grey seals once dropped to 40000 due to PCB pollution.becauseoxygen contentSerious shortage. In many areas of the Baltic Sea, large areas of the seabed have evolved into "underwater deserts"sea plantsAnd animal death.Scientists found only 4 areas with more frequent animal and plant activities in 47 investigated areas, while there was almost no animal and plant activity in 37 areasLife activitiesSigns.
In the area 50 – 60 meters below the surface of the Baltic Sea, the oxygen content is close to zero, andhydrogen sulfide, nitrogen and phosphorus content is relatively rich.The automatic purification rate of seawater in the Baltic Sea Area is very slow.If this situation continues, the living things in the sea area are likely to be extinct.
world record
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The world's lightest sea:The Baltic Sea, the lowest salinity sea in the world, has a salinity of only 0.7% – 0.8%.（Guinness World Records）
Maritime rights and interests
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In August 2022, Russian President Putin signed a new version of the National Ocean Theory.In the Atlantic direction, Russia believes thatthe WestMaritime activities in the Baltic Sea "seriously affect Russia's maritime security andNational interests”Russia will cooperate withmilitary strengthBuilding "to guard the direction ofMaritime rights and interests”。[5]
