Cold current refers to the large-scale flow of sea water from high latitude sea areas to low latitude sea areasocean currentThe category of (sea water) flow.[2]The water temperature of the cold current is lower than that of the area it is in, which can cool and dehumidify the place it passes by.
The cold current itself is lower than the surrounding water temperature, and is an important member of the ocean current family in the world's oceans.As an emissary of the cold ocean, it flows from the high latitude or polar ocean to the middle and low latitude regions, bringing a cool atmosphere to the sea area it flows through.
meaning
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characteristic
The cold current is characterized by low temperature, less salt content, low transparency, slow flow speed, wide range and small depth compared with the local seawater in the basin it passes through.In the process of flowing to the middle and low latitudes, the cold current keeps contacting with the surrounding sea waterHybrid switchingThe temperature and salinity gradually increase, the density of the upper layer decreases, and the cold water forms between the local waterDensity changeSharp water layer——Pycnocline, which has a great impact on underwater ship activities.
There is a transverse flow from east to northwest in the Bering Seaocean current, some of which areBering StraitFlowing into the Arctic Ocean;The other part joins the Annadel cold current from north to south on the west bankSiberiaThe eastern coast flows to the southwest, forming a powerfulKamchatka Cold Current, the mainstream of which is through KomandorstraitEntering the Pacific Ocean, this is the source of pro tide.
Tide loving continues to flow southward along the Kuril Islands, and the flow range extends to the east and west, just like the rivers in high mountains and valleys suddenly enter Hiragawa. The water flow widens. In the southern sea of Hokkaido, Japan, the main tributary is about 130~150 kilometers wide, and its center is 100~200 meters deep underwater, and it is divided into several branches.
stay40 degrees north latitude, the vast sea area in eastern Japanthe kuroshioThe northward branches of the Kuroshio River converge, presenting a "distinct" interface between the nearly green cold tide water and the dark blue Kuroshio warm water.A part of the tide after convergence flows left to the eastNorth Pacific Warm CurrentThe other part sinks below the Kuroshio and continues to flow southward as an undercurrent, which can reach around 10 degrees north latitude.
In the cold current areaair temperature It is higher than the average temperature of the sea water below, and the water vapor in the air is easy to cool and condense intodropletTherefore, the sea surface in the cold current basin is mostlySea fogThe frequent occurrence area of is very unfavorable to the navigation of ships at sea.Lower layer temperature is low, upper layer temperature is high,Atmospheric stratificationIt is stable and is not easy to have up and down convection activities, so there is little precipitation. Coastal and islands near the cold current are mostlyArid area。for exampleSouth AmericaOfPeruAlong the coast, affected by the northward Peru cold current, most of the year is covered by sea fog, with little rainAnnual precipitationIt is also mostly caused by fog drops.
Westerly drift
Southern hemisphereWesterly driftIt is the most powerful cold current in the worldAntarctica, the cold current flowing from west to east, due toPrevailing westerly windIs formed by the action of.Because it is in high latitude, coupled with Antarctic icebergs andfloating iceHere, it absorbs a lot of heat from the sea water, resulting in its cold current nature.
The westerly drift has a huge scale, with a width of 900~2000km. It is located in the South Atlantic Ocean and the South Indian OceanSouth Latitude43 °~60 ° atAfrican continentSouth end, due to strongWesterliesWith the effect of Benguela cold current, westerly drift can extend to 40 ° south latitude, which is also the farthest latitude that westerly drift extends to the north.It is located in the south of the South Pacific, 48 °~62 ° south latitude.The westerly drift has prevented the warm water in the north from entering the Antarctic sea area, and also prevented the cold air and icebergs in Antarctica from moving northward, which is conducive to maintaining the extremely cold climate and hugeIce fieldPlayed an essential role.
The westerly drift separates the branch Peru Cold Current on the west coast of South America, which is the largest branch of the westerly drift, and the Falkland Cold Current on the east coast of South AmericaAfricaBenguela cold current is separated from the west bankAustraliaThe West Bank separates the Western Australian Cold Current.
effect
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1. Most of the areas where the cold current passes are accompanied byUpflowappear.Rich deepwaterNutrient saltsIs taken to the upper layer, andoxygen contentHigh, so these areas are manyfishThe sea area where food and life are concentrated is a natural excellent fishing ground, such asSouth AmericaWesternPeru Fishing Ground。
2. Cold current flows through, makingSea surface temperatureThe water vapor is easy to condense and form fog, which affects shipping.
4. The cold current carries icebergs and ice floes from the north and south poles into the middle and low latitudes, posing a serious threat to maritime navigation.In particular, the cold current moving southward from the Arctic Ocean can carry icebergs to 40 ° north latitude.
misunderstanding
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Cold current andcold waveNot the same concept.Although the cold current is rightcoastal areasBut the cold current is not a cold wave.When the cold wave orcold airWhen people go south, they will feel cold waves invading their skin. People usually mistakenly call cold waves cold waves. In fact, they arehabituationLanguage error for.[2]
