The influence of currents on climate. How do sea currents affect the weather?
Big influence Currents influence the climate of continents. In this publication we will consider warm currents.
Concept
This is forward movement water masses in sea and ocean spaces, which is caused by the action various forces. Directing them to to a large extent depends on the axial rotation of the Earth.
Based on various criteria, scientists identify several classifications of currents. In the article we will consider the temperature criterion, that is, warm and in them the water temperature, respectively, is higher or lower than the level environment. Warm ones are a few degrees higher, cold ones lower. Warm currents are directed from warmer latitudes to cooler ones, and cold currents - vice versa.
The first increase the air temperature by three to four degrees and add precipitation. Others, on the contrary, reduce temperatures and precipitation.
The average annual temperature of warm currents varies from +15 to +25 degrees. They are indicated on the map by red arrows indicating the direction of their movement. Below we will consider what warm currents there are in the World Ocean.
Gulf Stream
One of the most famous warm sea currents, which transports millions of tons of water every second. This is a powerful water flow, thanks to which many European countries formed mild climate. Flows in the Atlantic Ocean along the coast North America and reaches the island of Newfoundland.
The Gulf Stream is the whole system warm, the width of which reaches eighty kilometers. He is rightfully considered the most important element in thermal regulation of the entire planet. Thanks to him, Ireland and England did not become a glacier.
When colliding with the Labrador Current, the Gulf Stream forms so-called eddies in the ocean. Further, it partially loses its energy as a result of the influence of various factors, as a result of which the water flow is reduced.
IN Lately some scientists say that the Gulf Stream has changed its direction. Now it is moving towards Greenland, creating more warm climate in America and colder in Russian Siberia.
Kuroshio
Another of the warm currents, which is located in Pacific Ocean off the Japanese coast. The name in translation has the meaning " dark waters". It carries the warm waters of the seas to northern latitudes, whereby climatic conditions regions are softening. The speed of the current ranges from two to six kilometers per hour, and the width reaches almost 170 kilometers. In summer, the water warms up to almost thirty degrees Celsius.
Kuroshio is very similar to the aforementioned Gulf Stream. It also significantly influences the weather conditions of the Japanese islands of Kyushu, Honshu and Shikoku. In the west there is a difference in surface water temperatures.
Brazilian Current
Another current passing through Atlantic Ocean. It is formed from the Equatorial Current and is located near the coast of South America, or more precisely, it passes near the Brazilian coast. That's why it has such a name. At the Cape of Good Hope it changes its name to the Transverse Current, and then off the coast of Africa to the Benguela (South African) Current.
It reaches speeds of up to two to three kilometers per hour, and the water temperature ranges from eighteen to twenty-six degrees above zero. In the southeast it encounters two cold currents - the Falkland Current and the West Wind Current.
Guinea Current
The warm Guinea Current flows slowly off the western African coast. In the Gulf of Guinea it moves from west to east and then turns south. Together with other currents, it forms a gyre in the Gulf of Guinea.
Average annual temperatures are 26-27 degrees Celsius above zero. When moving from west to east, the speed drops, in some places reaching more than forty kilometers per day, sometimes reaching almost ninety kilometers.
Its boundaries change throughout the year. In summer they expand and the current moves slightly north. In winter, on the contrary, it shifts to the south. The main source of nutrition is the warm Southern Trade Wind Current. The Guinea Current is superficial because it does not penetrate deep into the water column.
Alaska Current
Another warm current is in the Pacific Ocean. It is part of the system Passing through the Gulf of Alaska, it enters the top of the bay in the north and moves to the southwest. At this point the current intensifies. Speed - from 0.2 to 0.5 meters per second. In summer, the water warms up to fifteen degrees above zero, and in February the water temperature is two to seven degrees above zero.
It can go to great depths, right to the bottom. Present during seasonal changes caused by winds.
Thus, the article revealed the concept of “warm and cold currents”, and also examined warm sea currents that form a warm climate on the continents. In combination with other currents, they can form entire systems.
1The article makes an attempt to clarify the issue of the degree of influence of ocean surface currents on the climatic parameters of the adjacent land. The leading role of the ocean in the entire climate system of the Earth has been determined. It has been shown that the transfer of heat and moisture to land is carried out from the entire surface of the ocean by air masses. The role of surface ocean currents is to mix warm and cold water masses. It is noted that long-period Rossby waves, which are predominantly vertical, play a significant role in the heat exchange between the ocean and the atmosphere. water flows. It has been revealed that ocean currents act locally on adjacent land - only under the condition that the land area is very small and comparable to the size of the ocean current itself. In this case, depending on the relationship between the characteristics of the current itself and the adjacent land, small temperature changes are possible (both upward and downward). The direct influence of currents on the amount of precipitation on land could not be established.
ocean surface currents
ocean-atmosphere interaction
climate system
Gulf Stream
Rossby waves
1. Anisimov M.V., Byshev V.I., Zalesny V.B., Moshonkin S.N., Neiman V.G., Romanov Yu.A., Serykh I.V. About interdecadal variability climatic characteristics ocean and atmosphere in the North Atlantic region // Modern problems of remote sensing of the Earth from space. – 2012. – T. 9, No. 2. – P. 304–311.
2. Bondarenko A.L., Borisov E.V., Serykh I.V., Surkova G.V., Filippov Yu.G., Shchevyev V.A. On the influence of Rossby waves of the world ocean on the thermodynamics of its waters and atmosphere, weather and climate of the Earth // Meteorology and Hydrology. – 2011. – No. 4. – P. 75–81.
3. Kozina O.V., Dugin V.S. Climate-forming role ocean currents// Bulletin of Nizhnevartovsky state university. – 2013. – No. 3. – P. 22–31.
4. Rostom G.R. Common geographical truths against misconceptions // Geography at school. – 2013. – No. 5. – P. 57–60.
6. Gastineau G., Frankignoul C., D’Andrea F. Atmospheric response to the north Atlantic ocean variability on seasonal to decadal time scales // Climate Dynamics. – 2013. – V. 40, No. 9–10. – P. 2311–2330.
IN last years big interest raise questions related to changes in the characteristics of the Earth's climate system and their causes. It should be noted that systematic observations of climate change began relatively recently. Back in the 17th century, meteorology was part of the science of physics. It is to physicists that we owe the invention meteorological instruments. Thus, Galileo and his students invented a thermometer, a rain gauge, and a barometer. Only from the second half of the 17th century did instrumental observations begin to be made in Tuscany. At the same time, the first meteorological theories were developed. But it took almost two centuries on the way to systematic meteorological observations. They begin in the second half of the 19th century in Europe, after the invention of the telegraph. In the 1960s Was held big job to create a global network of weather observing systems. Lately, increasingly in the means mass media Reports began to appear about increasing cases of unusually high amounts of precipitation in Europe, sudden snowfall in tropical regions of the United States and North Africa, and flowering of plants in the Atacama Desert. For a long time, debates have not stopped about the degree of influence of the Gulf Stream on the climate of Europe, about the adverse consequences of the possible cessation of the functioning of this warm current. Unfortunately, the material is presented in such a way that it seems that the world has turned upside down and some catastrophic climate phenomena should be expected soon. The complex factual picture is fueled by various futuristic predictions about significant changes the usual order of things like a significant rise in sea level, a significant change in the angle of inclination earth's axis, a strong increase in the temperature of the surface layer of the atmosphere.
In this regard great importance has the clarification of the causes of climate phenomena, which should help to adequately perceive reality and take reasonable steps to adapt to upcoming changes. This article attempts to determine the degree of influence of ocean surface currents on the climate of the adjacent land. This aspect was chosen because in Earth science the influence of ocean currents on the climate of the adjacent land is slightly overestimated. Because of this, the role of the ocean in shaping the climate of land is downplayed, thereby distorting the understanding of the behavior of the Earth's climate system and delaying the moment of taking adequate adaptation measures.
There is an opinion that warm sea currents bring precipitation and heat to the adjacent land. This is taught in schools and universities. A comprehensive analysis of the existing picture shows the ambiguous manifestation of this postulate.
Ocean water can be considered as a storage device for solar heat on Earth. Ocean water absorbs 2/3 solar radiation. The heat capacity of the ocean is so great that ocean water (except for the surface layer) practically does not change temperature over the seasons (unlike the land surface). Therefore, it is warm on the ocean coast in winter and cool in summer. If the land area (compared to the ocean area) is small (as in Europe), then the warming influence of the ocean can spread over large areas. A close connection has been revealed between the loss of heat by the ocean and the warming of atmospheric air, and vice versa, which is logical. However, recent research data indicate a more complex picture of the thermal dynamics of the ocean and atmosphere. Scientists give the leading role in the loss of heat by the ocean to such a still little-studied phenomenon as the North Atlantic Oscillation. These are periodic multi-decadal changes in ocean temperature observed in the North Atlantic. Since the late 1990s. There was a wave of warming ocean water. As a result, in many areas northern hemisphere observed unusually a large number of hurricanes. Currently, there is a transition to a period of lowering the temperature of surface ocean waters. This will likely reduce the number of hurricanes in the northern hemisphere.
The seasonal constancy of the temperature of the entire mass of ocean water, especially in the tropics, led to the formation of permanent centers above the ocean surface high pressure, which are called centers of atmospheric action. Thanks to them, there is a general circulation of the atmosphere, which is the triggering mechanism general circulation ocean waters. Thanks to action constant winds surface currents of the World Ocean arise. With their help, ocean water is mixed, namely: the flow warm waters to cold areas (with the help of “warm” currents) and cool waters - to warm ones (with the help of “cold” currents). It must be remembered that these currents are “warm” or “cold” only in relation to the surrounding waters. For example, the temperature of the warm Norwegian Current is + 3 °C, the cold Peruvian Current is + 22 °C. Systems of ocean currents coincide with systems of constant winds and are closed rings. As for the Gulf Stream, it does bring heat to the waters of the North Atlantic (but not to Europe). In turn, the warm waters of the North Atlantic transfer their heat atmospheric air, which, together with western transport, may spread to Europe.
Recent studies on the issue of heat exchange between the ocean waters of the North Atlantic and the atmosphere have shown that the leading role in changing the temperature of ocean waters is played not so much by currents as by Rossby waves.
Thermal interaction between the ocean and the atmosphere occurs when the temperature of the surface layer of ocean water and the lower layer of air in the atmosphere differs. If the water temperature of the ocean surface layer more temperature lower layer of the atmosphere, then heat from the ocean is transferred to the atmosphere. Conversely, heat is transferred to the ocean if the air is warmer than the ocean. If the temperatures of the ocean and atmosphere are equal, then heat transfer between the ocean and atmosphere does not occur. In order for there to be a flow of heat between the ocean and the atmosphere, there must be mechanisms that change the temperature of the air or water in the ocean-atmosphere contact zone. On the atmospheric side, this can be wind; on the ocean side, these are mechanisms for the movement of water in the vertical direction, ensuring the supply of water with a temperature different from the temperature of the contact zone of the ocean and the atmosphere. Such vertical movements of water in the ocean are long-period Rossby waves. These waves differ from the wind waves we know in many ways. Firstly, they have longer length(up to several hundred kilometers) and lower altitude. Researchers usually judge their presence in the sea by changes in the vector of currents of water particles. Secondly, these are long-period inertial waves, the lifetime of which reaches ten or more years. Such waves are classified as gradient-vortex waves, which owe their existence to gyroscopic forces and are determined by the law of conservation of potential vortex.
In other words, the wind generates a flow, which in turn generates inertial waves. Applied to this movement water, the term “wave” is conditional. Water particles perform predominantly rotational movements, both in the horizontal and vertical planes. As a result, either warm or cold water masses rise to the surface. One of the consequences of this phenomenon is the movement and curvature (meaning) of current systems.
Research results and discussion
Currents as a special case of manifestation of the properties of ocean waters when certain factors can have a significant impact on the meteorological indicators of coastal land. For example, the warm East Australian Current further saturates the ocean air with moisture, from which precipitation falls as it rises along the Great Dividing Range in eastern Australia. The warm Norwegian Current melts arctic ice in the western part Barents Sea. As a result, the waters of the Murmansk port do not freeze in winter (while in Murmansk itself in winter the temperature drops below - 20 ° C). It also heats a narrow strip west coast Norway (Fig. 1, a). Thanks to the warm Kuroshio Current, eastern shores Japanese Islands winter temperatures higher than in the western part (Fig. 1, b).
Rice. 1. Distribution average annual temperatures air in Norway (a) and Japan (b); in deg. Celsius: red arrow indicates warm currents
Cold currents can also affect meteorological characteristics coastal land. Thus, cold currents in the tropics western shores South America, Africa and Australia (Peruvian, Benguela, Western Australian, respectively) deviate to the west, and even colder deep waters rise in their place. As a result, the lower layers of coastal air cool, a temperature inversion occurs (when the lower layers are colder than the upper ones) and the conditions for the formation of precipitation disappear. Therefore, some of the most lifeless deserts are located here - coastal ones (Atacama, Namib). Another example is the influence of the cold Kamchatka Current off the eastern coast of Kamchatka. It additionally cools the coastal areas (especially in summer) of the elongated small peninsula, and, as a consequence, southern border The tundra extends much south of the mid-latitude boundary.
At the same time, it should be noted that it is impossible to speak with a sufficient degree of certainty about the direct influence of warm ocean currents on the increase in the amount of precipitation on coastal land. Knowing the mechanism of precipitation formation, priority in its occurrence must be given to the presence mountain areas on the coasts along which the air rises, cools, moisture in the air condenses and precipitation forms. The presence of warm currents on the coast should be considered a coincidence or an additional stimulating factor, but not the main reason for the formation of precipitation. Where there are no large mountains (for example, in the east of South America and the Arabian coast of Southwest Asia), the presence of warm currents does not lead to an increase in precipitation (Fig. 2). And this despite the fact that in these areas the wind blows from the ocean to the land, i.e. All conditions exist for the full manifestation of the influence of warm currents on the coast.
Rice. 2. Distribution annual quantity precipitation in the east of South America (a) and the Arabian coast of South-West Asia (b): the red arrow indicates warm currents
As for the formation of precipitation itself, it is well known that they are formed when air rises upward and its subsequent cooling. In this case, moisture condenses and precipitation forms. Neither warm nor cold currents have a significant effect on the rise of air. There are three regions of the Earth in which ideal conditions exist for the formation of precipitation:
1) at the equator, where air masses are always ascending due to the existing atmospheric circulation system;
2) on the windward slopes of mountains, where air rises up the slope;
3) in temperate regions affected by cyclones, where air flows are always upward. On the world precipitation map, you can see that it is in these areas of the earth that the amount of precipitation is greatest.
An important condition for the formation of precipitation is favorable stratification of the atmosphere. Thus, on a number of islands located in the center of the oceans, especially in areas adjacent to subtropical anticyclones, rain falls extremely rarely throughout the year, despite the fact that the moisture content of the air here is quite high, and moisture transfer exists here towards these islands . Most often, this situation is observed in the trade wind region, where the rising currents are weak and do not reach the level of condensation. The formation of a trade wind inversion is explained by the heating of air during its descent in the zone of subtropical anticyclones, followed by cooling lower layers from the colder water surface.
conclusions
Thus, the influence of surface ocean currents on the climate of the adjacent land is local and appears only when certain factors coincide. A favorable confluence of factors is manifested by at least, in two types of regions of the Earth. Firstly, in small areas comparable to the size of the currents. Secondly, in areas with extreme (high or low) temperatures. In these cases, if the water is warmer, the narrow coastal strip of land will be warmed (North Atlantic Current in Britain). If the current water temperature is lower, on the contrary, the narrow coastal strip of land will cool ( Peruvian Current off the west coast of South America). In general, the greatest influence on the supply of heat to land is exerted by the entire mass of ocean water through the transfer of heat by circulating atmospheric flows.
Moisture comes to land in the same way - from the surface of the entire ocean through atmospheric currents. In this case, one thing must be fulfilled additional condition- in order for the air to release the moisture received over the ocean, it must rise to the upper layers of the atmosphere to cool. Only then does the moisture condense and precipitation occurs. Ocean currents play a very minor role in this process. Most of all, ocean currents (cold in tropical latitudes) contribute to precipitation deficit. This manifests itself during the passage of cold currents in the tropics off the western coasts of South America, Africa and Australia.
As for the areas lying in the interior of the continent, for example, the Central Black Earth regions of the Russian Plain, the nature atmospheric circulation in the frost-free period of the year it determines predominantly the anticyclonic regime, sunny weather, formed in masses of continental temperate air. Marine air masses come to a given territory mainly in a modified form, having lost a significant part of their basic properties along the way.
When talking about the influence of the Gulf Stream on the climate of Europe, we must keep in mind two important points. Firstly, by the Gulf Stream in this case it is necessary to understand the entire system of warm North Atlantic currents, and not the Gulf Stream itself (it is North American and has nothing to do with Europe). Secondly, remember about the supply of heat and moisture from the surface of the entire Atlantic Ocean through their transport by air masses. A warm ocean current alone is clearly not enough to warm the whole of Europe.
In the end, it is necessary to recall that, being wind-driven, the surface currents of the World Ocean are unlikely to disappear as long as the atmospheric circulation system established on Earth exists.
Bibliographic link
Anichkina N.V., Rostom G.R. ON THE DEGREE OF INFLUENCE OF OCEAN SURFACE CURRENTS ON THE CLIMATE OF ADJACENT LAND // Advances modern natural science. – 2016. – No. 12-1. – pp. 122-126;URL: http://natural-sciences.ru/ru/article/view?id=36273 (access date: 03/29/2019). We bring to your attention magazines published by the publishing house "Academy of Natural Sciences"
Ocean currents redistribute what is absorbed solar heat in the horizontal direction and significantly influence the climate coastal areas which they wash.
Yes, it's cold Bengal Current lowers the air temperature of the coastal part West Africa. In addition, it is not conducive to rainfall, because... cools the lower layers of air in the coastal part, and cold air, as you know, it becomes heavier, denser, cannot rise, form clouds and give precipitation.
Warm currents ( Mozambique, Cape Agulhas Current), on the contrary, increase the air temperature on the eastern coast of the continent, contribute to the saturation of the air with moisture and the formation of precipitation.
Warm East Australian Current, washing the coast of Australia, causes an abundance of precipitation on the eastern slopes Great Dividing Range.
Cold Peruvian Current, passing along the western coast of South America, greatly cools the air of coastal areas and does not contribute to precipitation. Therefore here is Atacama Desert, where rain is a rare occurrence.
The warm current has a great influence on the climate of both Europe and North America. Gulf Stream (North Atlantic). Scandinavian Peninsula lies at approximately the same latitudes as Greenland island. However, the last all year round covered with a thick layer of snow and ice, while in the southern part of the Scandinavian Peninsula, washed by the North - Atlantic current, coniferous and broad-leaved forests grow.
Ebbs and flows
Periodic fluctuations in ocean (sea) level caused by the gravitational forces of the Moon and the Sun are tides And low tides.
Tidal currents in the World Ocean arise under the influence of gravitational forces (forces of attraction) of the Moon and the Sun. These are periodic fluctuations in water levels off the coasts of the open sea. The tidal force of the Moon is almost 2 times greater than the tidal force of the Sun. In the open sea, the tide is no more than 1 m, but upon entering narrowing bays the tidal wave rises; the highest tidal heights in the Bay of Fundy in southeastern Canada are 18 m. The frequency of tides can be semidiurnal, diurnal or mixed.
The world's oceans have great value in people's lives. This is a source of natural resources: biological(fish, seafood, pearls, etc.) and mineral(oil Gas). This is a transport space and a source of energy resources.
The circulation of the waters of the World Ocean determines the exchange of matter, heat and mechanical energy between the ocean and the atmosphere, surface and deep, tropical and polar waters. Sea currents carry large masses water from one area to another, often to very remote areas. Currents disrupt the latitudinal zonality in the temperature distribution. In all three oceans - the Atlantic, Indian and Pacific - under the influence of currents, temperature anomalies: positive anomalies are associated with the transfer of warm waters from the equator to higher latitudes by currents close to meridional direction; negative anomalies are caused by oppositely directed (from high latitudes to the equator) cold currents. Negative temperature anomalies are intensifying, in addition, with the rise deep waters off the western coasts of the continents, caused by the movement of water by trade winds.
The influence of currents affects not only the magnitude and distribution of average annual temperature values, but also its annual amplitudes. This is especially clearly manifested in areas of contact between warm and cold currents, where their boundaries shift throughout the year, such as, for example, in the Atlantic Ocean in the area of contact of the Gulf Stream and Labrador Currents, in the Pacific Ocean in the area of contact of the Kuroshio and Kuril (Oyashio) currents. .
Currents influence the distribution of other oceanological characteristics: salinity, oxygen content, nutrients, color, transparency, etc. The distribution of these characteristics has a huge impact on the development biological processes, vegetable and animal world seas and oceans. Variability of sea currents in time and space, their displacement frontal zones affect the biological productivity of oceans and seas.
Currents have a great influence on the Earth's climate. For example, in tropical areas, where eastern transport predominates, significant cloudiness, precipitation, and humidity are observed on the western shores of the oceans, while on the eastern shores, where winds blow from the continents, there is a relatively dry climate. Currents significantly influence pressure distribution and atmospheric circulation. A series of cyclones move above the axes of warm currents, such as the Gulf Stream, North Atlantic, Kuroshio, and North Pacific, which determine the weather conditions of the coastal regions of the continents. The warm North Atlantic Current favors the strengthening of the Icelandic low pressure, and, consequently, intense cyclonic activity in the North Atlantic, North and Baltic seas. The influence of Kuroshio on the area of the Aleutian low pressure in the northeastern region of the Pacific Ocean is similar. Warm currents penetrating into high latitudes are associated with cyclonic circulation of the atmosphere, which contributes to heavy precipitation. atmospheric precipitation. On the contrary, high pressure spurs develop above cold currents, which causes a decrease in precipitation. In areas where warm and cold currents meet, fogs and overcast.
Where warm currents penetrate deeply into temperate and subpolar latitudes, their influence on the climate is especially pronounced. The moderating influence of the Gulf Stream, the North Atlantic Current and its branches on the climate of Europe, and the Kuroshio Current on the climatic conditions of the northern part of the Pacific Ocean are well known. It should be noted higher value in this respect, the North Atlantic Current than Kuroshio, since the North Atlantic Current penetrates almost 40° north of Kuroshio.
Sharp differences in climate are created when the shores of continents or oceans are washed by cold and warm currents. For example, East Coast Canada is under the influence of the cold Labrador Current, while the western coast of Europe is washed by the warm waters of the North Atlantic Current. As a result, in the zone between 55 and 70° N. w. The duration of the frost-free period on the Canadian coast is less than 60 days, on the European coast - 150-210 days. A striking example The influence of currents on climatic and weather conditions is the Chilean-Peruvian cold current, the water temperature of which is 8-10° lower than the surrounding waters of the Pacific Ocean. Above the cold waters of this current, air masses, cooling, form a continuous cover stratocumulus clouds, as a result, the coasts of Chile and Peru are experiencing continuous cloudiness and no precipitation. The southeastern trade wind creates a surge in this area, i.e., the departure of surface waters from the shore and the rise of cold deep waters. When the coast of Peru is only under the influence of this cold current, this period is characterized by the absence of tropical storms, rains and thunderstorms, and in the summer, especially when the oncoming warm coastal current intensifies El Niño currents, tropical storms, destructive thunderstorms, downpours that erode the soil, residential buildings, dams, and embankments are observed here.
Pulsations of ocean currents, meandering and displacement of their axes to the south or north have a significant impact on the climate of coastal areas. Simultaneous observations of the temperature distribution within such large-scale flows as the Gulf Stream and Kuroshio revealed meanders (meanders) that have a wave-like character. They resemble river meanders and, in the form of condensation of isotherms in the axis of the main flow, move along with the current. For example, the shift of the Kuroshio axis to the south and north reaches 350 miles between 34 and 40 ° N. w. The position of the fronts Kuroshio - Oyashio, Gulf Stream - Labrador and other currents experiences semi-monthly, monthly, semi-annual, annual and long-term fluctuations. In this regard, fluctuations in climatological and meteorological factors are observed on the coasts of nearby continents. Weather Japan is associated with fluctuations of the Kuroshio front, the climatic conditions of the Kuril ridge, about. Hokkaido and the north of. Honshu is influenced by the cold Oyashio Current.
16.11.2007 13:52
Current is the movement of water particles from one place in the ocean or sea to another.
Currents cover huge masses of ocean waters, spreading wide stripe on the surface of the ocean and capturing a layer of water of varying depth. On great depths and near the bottom there are slower movements of water particles, most often reverse direction compared to surface currents, which are part of the general water cycle of the World Ocean.
The main forces causing sea currents are determined by both hydrometeorological and astronomical factors.
The first should include:
1) density force or driving force currents created by density differences due to uneven changes in temperature and salinity of sea water
2) the slope of sea level caused by excess or lack of water in a particular area, due to, for example, coastal runoff or wind surges and surges
3) sea level slope caused by changes in distribution atmospheric pressure, creating a decrease in sea level in areas of high atmospheric pressure and a rise in levels in areas of low pressure
4) wind friction on the surface of the sea waters and wind pressure on the rear surface of the waves.
The second ones include tidal forces of the Moon and the Sun, continuously changing due to periodic changes in the relative positions of the Sun, Earth and Moon and creating horizontal fluctuations of water masses or tidal currents.
Immediately after the occurrence of a flow caused by one or more of these forces, secondary forces arise that influence the flow. These forces are incapable of causing currents; they only modify the current that has already arisen.
These forces include:
1) the Coriolis force, which deflects any moving body to the right in the northern hemisphere, and to the left in the southern hemisphere from the direction of its movement, depending on the latitude of the place and the speed of movement of the particles
2) friction force, slowing down any movement
3) centrifugal force.
Sea currents are divided according to the following characteristics:
1. By origin, i.e. according to the factors that cause them - a) density (gradient) currents; b) drift and wind currents; c) waste or runoff currents; d) barogradient; e) tidal; f) compensatory currents, which are a consequence of the almost complete incompressibility of water (continuity), arise due to the need to compensate for the loss of water, for example, from the drive of water by the wind or its outflow due to the presence of other currents.
2. By region of origin.
3. By duration or stability: a) constant currents flowing from year to year in the same direction at a certain speed; b) temporary currents caused by transient causes and changing their direction and speed depending on the time of action and the magnitude of the generating force; c) periodic currents that change their direction and speed in accordance with the period and magnitude of tidal forces.
4. By physical and chemical characteristics, for example, warm and cold. Moreover absolute value temperature does not matter for flow characteristics; the temperature of the waters of warm currents is higher than the temperature of the waters created by local conditions, the temperature of the waters of cold currents is lower.
Main currents in the Pacific Ocean influencing the climate of Primorye
Kuroshio (Kuro-Shio) The Kuroshio system is divided into three parts: a) Kuroshio proper, b) Kuroshio drift and c) North Pacific Current. Kuroshio proper is the name given to the area of warm current in the western part of the northern half of the Pacific Ocean between the island of Taiwan and 35°N, 142°E.
The beginning of Kuroshio is the branch of the North Trade Wind Current, running north along the eastern shores Philippine Islands . Near the island of Taiwan, Kuroshio has a width of about 185 km and a speed of 0.8-1.0 m/s. Then it deviates to the right and passes along the western shores of the Ryukyu island ridge, and the speed at times increases to 1.5-1.8 m/s. An increase in Kuroshio speeds usually occurs in summer with tailwinds of the summer southeast monsoon.
On the approaches to the southern tip of Kyushu Island, the current splits into two branches: the main branch passes through Van Diemen's Strait to the Pacific Ocean (Kuroshio proper), and the other branch goes to Korea Strait(Tsushima Current). Kuroshio itself, when approaching the southeastern tip of the island of Honshu - Cape Najima (35° N, 140° E) - turns to the east, being pushed away from the coast by the cold Kuril Current.
At a point with coordinates 35°N, 142°E. Two branches separate from Kuroshio: one goes south and the other goes northeast. This last branch reaches far to the north. Traces of the northeastern branch can be observed up to Commander Islands.
The Kuroshio drift is the section of warm current between 142 and 160°E, after which the North Pacific Current begins.
The most stable of all three components of the Kuroshio system is the Kuroshio current itself, although it is subject to large seasonal fluctuations; so in December, during greatest development With the winter monsoon blowing from the north or northwest, where Kuroshio is usually located, ships often note southward currents. This indicates a strong dependence of the flow on monsoon winds, possessing off the eastern coast of Asia great strength and consistency.
Kuroshio's influence on climate coastal countries East Asia such that the warming of waters in the Kuroshio region causes an exacerbation of the winter monsoon in winter.
. Kuril Current
The Kuril Current, sometimes called the Oya Sio, is a cold current. It originates in the Bering Sea and flows first south under the name Kamchatka Current along the eastern shores of Kamchatka, and then along the eastern shores of the Kuril ridge.
IN winter time through the straits Kuril ridge(especially through its southern straits) masses enter the Pacific Ocean from the Sea of Okhotsk cold water, and sometimes ice, which greatly enhances Kuril Current. In winter, the speed of the Kuril Current fluctuates around 0.5-1.0 m/s, in summer it is slightly less - 0.25-0.35 m/s.
The cold Kuril Current flows first along the surface, penetrating south a little further than Cape Nojima - the southeastern tip of the island of Honshu. The width of the Kuril Current at Cape Nojima is about 55.5 km. Soon after passing the cape, the current drops under surface water ocean and continues for another 370 km in the form of an underwater current.
Main currents in the Sea of Japan
The Sea of Japan is located in the northwestern Pacific Ocean between the mainland coast of Asia, Japanese islands And Sakhalin Island V geographical coordinates 34°26"-51°41" N, 127°20"-142°15" E According to its physical and geographical position, it belongs to the marginal oceanic seas and is fenced off from adjacent basins by shallow barriers.
In the north and northeast, the Sea of Japan is connected to the Sea of Okhotsk by the Nevelskoy and La Perouse (Soya) straits, in the east - with Pacific Ocean, Sangar (Tsugaru) Strait, in the south - from East China Sea Korea (Tsushima) Strait. The smallest of them is the strait- Nevelskoy has maximum depth 10 m, a the deepest Sangarsky- about 200 m.
The greatest influence on the hydrological regime of the basin is exerted by subtropical waters entering through Korea Strait from the East China Sea. The movement of water in the Sea of Japan is formed as a result of the total effect of the global distribution of atmospheric pressure, wind field, heat and water flows. In the Pacific Ocean, isobaric surfaces tilt toward the Asian continent with a corresponding transfer of water. The Sea of Japan from the Pacific Ocean receives mainly the waters of the western branch of the warm Kuroshio, passing through the East China Sea and adding its waters.
Due to the shallowness of the straits, only surface water enters the Sea of Japan. Every year, from 55 to 60 thousand km3 of warm water enters the Sea of Japan through the Korean Irrigation. The stream of these waters in the form Tsushima Current changes throughout the year. It is most intense at the end of summer - beginning of autumn, when, under the influence of the southeast monsoon, the western branch of Kuroshio strengthens and water surges into East China Sea. During this period, the water inflow increases to 8 thousand km3 per month. At the end of winter, the influx of water into the Sea of Japan through the Korean Irrigation decreases to 1.5 thousand km3 per month. Due to the passage of the Tsushima Current off the western coast of the Japanese Islands, sea level here is on average 20 cm higher than in the Pacific Ocean off the eastern coast of Japan. Therefore, already in the Sangar Strait, the first along the path of the waters of this current, there is an intense flow of water into the Pacific Ocean.
Approximately 62% of the waters of the Tsushima Current leave through this strait, as a result of which it then becomes greatly weakened. Another 24% of the volume of water coming from the Korea Strait flows through the La Perouse Strait, and already to the north its flow of warm water becomes extremely insignificant, but still an insignificant part of the water Tsushima Current penetrates into the summer Strait of Tartary. In it, due to the small cross-section of the Nevelskoy Strait, most of these waters turn south. As the flow of water in the Tsushima Current moves north, water from other currents is included in it and jets are diverted from it. In particular, the jets that deviate to the west in front of the Tatar Strait merge with the waters leaving it, forming a stream flowing at low speed to the south. Primorsky Current.
South of Peter the Great Bay, this current divides into two branches: the coastal one continues to move south and, in part in separate jets, together with the return waters of the Tsushima Current in eddy gyres, exits into Korea Strait, and the eastern jet deviates to the east and connects with the Tsushima Current. The coastal branch is called the North Korean Current.
The entire listed system of currents forms a cyclonic circulation common to the entire sea, in which the eastern periphery consists of a warm current, and the western periphery consists of a cold one.
Temperature distribution and speed on the surface of the Sea of Japan are presented according to the electronic Atlas of oceanography of the Bering, Okhotsk and Japanese seas(TOI FEB RAS) for January, March, May, July, September, October.
Current speeds in the southern half of the sea are higher than in the northern half. Calculated by the dynamic method they are in the upper 25 meter layer Tsushima Current decrease from 70 cm/s to Korea Strait to approximately 29 cm/s at the latitude of the La Perouse Strait and become less than 10 cm/s at Tatar Strait. The speed of the cold current is significantly lower. It increases to the south from several centimeters per second in the north to 10 cm/s in the southern part of the sea.
In addition to constant currents, drift and wind currents are often observed, which cause surges and surges of water. There are cases when the total currents, composed mainly of constant, drift and tidal currents, are directed at right angles to the shore or away from the shore. In the first case, they are called pressing, in the second, squeezing. Their speed usually does not exceed 0.25 m/s.
Water exchange through the straits has a dominant influence on the hydrological regime of the southern and eastern half Sea of Japan. Flowing through Korea Strait subtropical waters of the Kuroshio branch warm throughout the year southern regions seas and waters adjacent to the coast of the Japanese islands up to the La Perouse Strait, as a result of which the waters of the eastern part of the sea are always warmer than the western.
Literature: 1. Doronin Yu. P. Regional oceanology. - L.: Gidrometeoizdat, 1986.
2. Istoshin I.V. Oceanology. - L.: Gidrometeoizdat, 1953.
3. Sea of Japan pilotage. Part 1, 2. - L.: Navy Cart Factory, 1972.
4. Atlas of oceanography of the Bering, Okhotsk and Japan seas (POI FEB RAS). - Vladivostok, 2002
Head of OGMM
Yushkina K.A.