The Sea of Japan lies between the continent of Asia, the Korean Peninsula, and Sakhalin and the Japanese islands, separating it from the ocean and two neighboring seas. In the north, the border between the Sea of Japan and the Sea of Okhotsk runs along the line between Cape Sushchev and Cape Tyk on Sakhalin. In the La Perouse Strait, the border is the line between Cape Soya and Cape Crillon. In the Sangar Strait, the border runs along the line of Cape Syria - Cape Estan, and in the Korea Strait - along the line of Cape Nomo (Kyushu Island) - Cape Fukae (Goto Island) - Island. Jeju - Korean Peninsula.
The Sea of Japan is one of the largest and deepest seas in the world. Its area is 1062 km 2, volume - 1631 thousand km 3, average depth - 1536 m, greatest depth - 3699 m. This is a marginal oceanic sea.
There are no large islands in the Sea of Japan. Of the small ones, the most significant are the islands of Moneron, Rishiri, Okushiri, Ojima, Sado, Okinoshima, Ullyndo, Askold, Russky, and Putyatina. Tsushima Island is located in the Korea Strait. All islands (except Ulleungdo) are located near the coast. Most of them are located in the eastern part of the sea.
The coastline of the Sea of Japan is relatively slightly indented. The simplest in outline is the coast of Sakhalin; the coasts of Primorye and the Japanese Islands are more winding. The large bays of the mainland coast include De-Kastri, Sovetskaya Gavan, Vladimir, Olga, Peter the Great, Posyet, Koreysky, on the island. Hokkaido - Ishikari, on the island. Honshu - Toyama and Wakasa.
Landscapes of the Sea of Japan
The coastal boundaries are cut through by straits that connect the Sea of Japan with the Pacific Ocean, the Sea of Okhotsk and the East China Sea. The straits vary in length, width and, most importantly, depth, which determines the nature of water exchange in the Sea of Japan. Through the Sangar Strait, the Sea of Japan communicates directly with the Pacific Ocean. The depth of the strait in the western part is about 130 m, in the eastern part, where its maximum depths are located, about 400 m. The Nevelskoy and La Perouse straits connect the Sea of Japan and the Sea of Okhotsk. The Korea Strait, divided by the islands of Jeju, Tsushima and Ikizuki into the western (Broughton passage with the greatest depth of about 12.5 m) and eastern (Kruzenshtern passage with the greatest depth of about 110 m) parts, connects the Sea of Japan and the East China Sea. The Shimonoseki Strait, with depths of 2-3 m, connects the Sea of Japan with the Inland Sea of Japan. Due to the shallow depths of the straits and the great depths of the sea itself, conditions are created for isolating its deep waters from the Pacific Ocean and adjacent seas, which is the most important natural feature Sea of Japan.
The coast of the Sea of Japan, varied in structure and external forms in different areas, belongs to different morphometric types of coasts. These are predominantly abrasive, mostly unaltered, shores. To a lesser extent, the Sea of Japan is characterized by accumulative shores. This sea is surrounded by predominantly mountainous shores. In some places, single rocks - kekurs - characteristic formations of the Sea of Japan coast rise from the water. Low-lying shores are found only on certain sections of the coast.
Bottom relief
Bottom topography and currents of the Sea of Japan
According to the nature of the bottom topography, the Sea of Japan is divided into three parts: northern - north of 44° N, central - between 40 and 44° N. and southern - south of 40° N.
The northern part of the sea is like a wide trench, gradually rising and narrowing towards the north. Its bottom in the direction from north to south forms three steps, which are separated from one another by clearly defined ledges. The northern step is located at a depth of 900-1400 m, the middle one is at a depth of 1700-2000 m, and the southern step is at a depth of 2300-2600 m. The surfaces of the steps are slightly inclined to the south.
The coastal sandbank of Primorye in the northern part of the sea is approximately 20 to 50 km long, the edge of the sandbank is located at a depth of about 200 m.
The surfaces of the northern and middle steps of the central trough are more or less level. The relief of the southern step is significantly complicated by numerous individual uplifts up to 500 m high. Here, on the edge of the southern step, at a latitude of 44°, there is a vast hill called “Vityaz” with a minimum depth above it of 1086 m.
The southern step of the northern part of the Sea of Japan breaks off with a steep ledge to the bottom of the central basin. The steepness of the ledge is on average 10-12°, in some places 25-30°, and the height is approximately 800-900 m.
The central part of the sea is a deep closed basin, slightly elongated in the east-northeast direction. From the west, north and east it is limited by the steep slopes of mountain structures sloping into the sea in Primorye, the Korean Peninsula, the islands of Hokkaido and Honshu, and from the south by the slopes of the Yamato underwater hill.
In the central part of the sea, coastal shallows are very poorly developed. A relatively wide sandbank is found only in the area of southern Primorye. The edge of the shallows in the central part of the sea is very clearly expressed throughout its entire length. The bottom of the basin, located at a depth of about 3500 m, in contrast to the complexly dissected surrounding slopes, is leveled. On the surface of this plain there are isolated hills. Approximately in the center of the basin there is an underwater ridge stretching from north to south with a height of up to 2300 m. The southern part of the sea has a very complex topography, since in this area there are the marginal parts of large mountain systems - the Kuril-Kamchatka, Japanese and Ryu-Kyu. Here is the vast underwater Yamato Rise, which consists of two ridges elongated in the east-northeast direction with a closed basin located between them. From the south, a wide underwater ridge of approximately meridional strike adjoins the Yamato Rise.
In many areas of the southern part of the sea, the structure of the underwater slope is complicated by the presence of underwater ridges. On the underwater slope of the Korean Peninsula, wide underwater valleys can be traced between the ridges. The continental shelf is no more than 40 km wide throughout almost its entire length. In the area of the Korea Strait, the shallows of the Korean Peninsula and about. The Honshu close together and form shallow waters with depths of no more than 150 m.
Climate
The Sea of Japan lies entirely in the monsoon climate zone of temperate latitudes. In the cold season (from October to March) it is influenced by the Siberian anticyclone and the Aleutian low, which is associated with significant horizontal gradients of atmospheric pressure. In this regard, strong northwest winds with speeds of 12-15 m/s and more dominate over the sea. Local conditions change wind conditions. In some areas, under the influence of coastal topography, there is a high frequency of northern winds, while in others, calms are often observed. On the southeastern coast, the regularity of the monsoon is disrupted; western and northwestern winds predominate here.
During the cold season, continental cyclones enter the Sea of Japan. They cause strong storms, and sometimes severe hurricanes, which last for 2-3 days. At the beginning of autumn (September), tropical cyclones-typhoons sweep over the sea, accompanied by hurricane winds.
The winter monsoon brings dry and cold air, the temperature of which increases from south to north and from west to east. In the coldest months - January and February - the average monthly air temperature in the north is about -20°, and in the south about 5°, although significant deviations from these values are often observed. During the cold seasons, the weather is dry and clear in the northwestern part of the sea, wet and cloudy in the southeast.
In warm seasons, the Sea of Japan is affected by the Hawaiian High and, to a lesser extent, by the depression that forms in the summer over Eastern Siberia. In this regard, southern and southwestern winds prevail over the sea. However, pressure gradients between areas of high and low pressure are relatively small, so wind speeds average 2-7 m/s. A significant increase in wind is associated with the entry of oceanic, and less often continental, cyclones into the sea. In summer and early autumn (July-October), the number of typhoons over the sea increases (with a maximum in September), causing hurricane-force winds. In addition to the summer monsoon, strong and hurricane winds associated with the passage of cyclones and typhoons, local winds are observed in different areas of the sea. They are mainly caused by the peculiarities of coastal orography and are most noticeable in the coastal zone.
In the Far Eastern seas
The summer monsoon brings warm and humid air. The average monthly temperature of the warmest month - August - in the northern part of the sea is approximately 15°, and in the southern regions about 25°. In the northwestern part of the sea, significant cooling is observed due to the influx of cold air brought by continental cyclones. In spring and summer, cloudy weather with frequent fogs prevails.
A distinctive feature of the Sea of Japan is the relatively small number of rivers flowing into it. The largest of them is Suchan. Almost all rivers are mountainous. Continental flow into the Sea of Japan is approximately 210 km 3 /year and is fairly evenly distributed throughout the year. Only in July does the river flow increase slightly.
The geographical location, the outlines of the sea basin, separated from the Pacific Ocean and adjacent seas by high thresholds in the straits, pronounced monsoons, water exchange through the straits only in the upper layers are the main factors in the formation of the hydrological conditions of the Sea of Japan.
The Sea of Japan receives a large amount of heat from the sun. However, the total heat consumption for effective radiation and evaporation exceeds the input solar heat Therefore, as a result of processes occurring at the water-air interface, the sea loses heat annually. It is replenished by the heat brought by Pacific waters entering the sea through the straits, therefore, on the average long-term value, the sea is in a state of thermal equilibrium. This indicates important role water heat exchange, mainly heat influx from outside.
Hydrology
Significant natural factors are the exchange of water through the straits, the flow of precipitation onto the sea surface and evaporation. The main influx of water into the Sea of Japan occurs through the Korea Strait - about 97% of the total annual amount of incoming water. The largest flow of water goes through the Sangar Strait - 64% of the total flow; 34% flows through the La Perouse and Korean straits. The share of fresh components of the water balance (continental runoff, precipitation) remains only about 1%. Thus, the main role in the water balance of the sea is played by water exchange through the straits.
Scheme of water exchange through straits in the Sea of Japan
Features of the bottom topography, water exchange through the straits, and climatic conditions form the main features of the hydrological structure of the Sea of Japan. It is similar to the subarctic type of structure of the adjacent areas of the Pacific Ocean, but has its own characteristics that have developed under the influence of local conditions.
The entire thickness of its waters is divided into two zones: surface - to a depth of an average of 200 m and deep - from 200 m to the bottom. The waters of the deep zone are relatively uniform in physical properties throughout the year. The characteristics of surface water under the influence of climatic and hydrological factors change in time and space much more intensely.
In the Sea of Japan, three water masses are distinguished: two in the surface zone: the surface Pacific, characteristic of the southeastern part of the sea, and the surface Sea of Japan - for the northwestern part of the sea, and one in the deep part - the deep Sea of Japan water mass.
The surface Pacific water mass is formed by the water of the Tsushima Current; it has the largest volume in the south and southeast of the sea. As you move north, its thickness and area of distribution gradually decrease, and at approximately 48° N latitude. due to a sharp decrease in depth, it wedges out into shallow water. In winter, when the Tsushima Current weakens, the northern boundary of the Pacific waters is located at approximately 46-47° N latitude.
Water temperature and salinity
Surface Pacific water is characterized by high temperatures (about 15-20°) and salinity (34-34.5‰). This water mass contains several layers, the hydrological characteristics of which and their thickness vary throughout the year:
the surface layer, where the temperature throughout the year varies from 10 to 25°, and salinity - from 33.5 to 34.5‰. The thickness of the surface layer varies from 10 to 100 m;
the upper intermediate layer has a thickness varying from 50 to 150 m. It exhibits significant gradients in temperature, salinity and density;
the lower layer has a thickness of 100 to 150 m. The depth of its occurrence and the boundaries of its distribution change throughout the year; temperature varies from 4 to 12°, salinity - from 34 to 34.2‰. The lower intermediate layer has very slight vertical gradients in temperature, salinity and density. It separates the surface Pacific water mass from the deep Sea of Japan.
As you move north, the characteristics of Pacific water gradually change under the influence climatic factors as a result of its mixing with the underlying deep Sea of Japan water. With the cooling and desalination of Pacific water at latitudes 46-48° N. The surface water mass of the Sea of Japan is formed. It is characterized by relatively low temperature (on average about 5-8°) and salinity (32.5-33.5‰). The entire thickness of this water mass is divided into three layers: surface, intermediate and deep. As in the Pacific Ocean, in the surface water of the Japanese Sea, the greatest changes in hydrological characteristics occur in the surface layer with a thickness of 10 to 150 m or more. The temperature here varies throughout the year from 0 to 21°, salinity - from 32 to 34‰. In the intermediate and deep layers, seasonal changes in hydrological characteristics are insignificant.
Deep Sea of Japan water is formed as a result of the transformation of surface waters that descend to depths due to the process of winter convection. The vertical changes in the characteristics of the deep Sea of Japan water are extremely small. The bulk of these waters have a temperature of 0.1-0.2° in winter, 0.3-0.5° in summer, and a salinity throughout the year of 34.1-34.15‰.
Water temperature on the surface of the seas of Japan, Yellow, East China, South China, Philippines, Sulu, Sulawesi in summer
The structural features of the waters of the Sea of Japan are well illustrated by the distribution of oceanological characteristics in it. Surface water temperatures generally increase from northwest to southeast.
In winter, the water temperature on the surface rises from negative values close to 0° in the north and northwest to 10-14° in the south and southeast. This season is characterized by a well-defined contrast in water temperature between the western and eastern parts of the sea, and in the south it is weaker than in the north and central part of the sea. Thus, at the latitude of Peter the Great Bay, the water temperature in the west is close to 0°, and in the east it reaches 5-6°. This is explained, in particular, by the influence of warm waters moving from south to north in the eastern part of the sea.
As a result of spring warming, the surface water temperature throughout the sea rises quite quickly. At this time, temperature differences between the western and eastern parts of the sea begin to smooth out.
In summer, the surface water temperature rises from 18-20° in the north to 25-27° in the south of the sea. Temperature differences across latitude are relatively small.
On the western shores, the surface water temperature is 1-2° lower than on the eastern shores, where warm waters spreading from south to north.
In winter, in the northern and northwestern regions of the sea, the vertical water temperature changes slightly, and its values are close to 0.2-0.4°. In the central, southern and southeastern parts of the sea, the change in water temperature with depth is more pronounced. In general, the surface temperature, equal to 8-10°, remains up to horizons of 100-150 m, from which it gradually decreases with depth to approximately 2-4° at horizons of 200-250 m, then it decreases very slowly - to 1-1. 5° at horizons of 400-500 m, deeper the temperature drops slightly (to values less than 1°) and remains approximately the same to the bottom.
In summer, in the north and northwest of the sea, high surface temperature (18-20°) is observed in the 0-15 m layer, from here it drops sharply with a depth of up to 4° at a horizon of 50 m, then its decrease occurs very slowly to a horizon of 250 m, where it is approximately 1°, deeper and to the bottom the temperature does not exceed 1°.
In the central and southern parts of the sea, the temperature decreases quite smoothly with depth and at a horizon of 200 m is approximately 6°, from here it decreases somewhat faster and at horizons of 250-260 m it is equal to 1.5-2°, then it decreases very slowly at horizons 750-1500 m (in some areas at horizons of 1000-1500 m) reaches a minimum of 0.04-0.14°, from here the temperature rises towards the bottom to 0.3°. The formation of an intermediate layer of minimum temperature values is presumably associated with the immersion of the cooled in harsh winters waters of the northern part of the sea. This layer is quite stable and is observed all year round.
Salinity on the surface of the seas of Japan, Yellow, East China, South China, Philippines, Sulu, Sulawesi in summer
The average salinity of the Sea of Japan, approximately 34.1‰, is slightly lower than the average salinity of the waters of the World Ocean.
In winter, the highest salinity of the surface layer (about 34.5‰) is observed in the south. The lowest surface salinity (about 33.8‰) is observed along the southeastern and southwestern coasts, where heavy precipitation causes some desalination. In most of the sea, salinity is 34.l‰. In spring, in the north and northwest, desalination of surface water occurs due to melting ice, and in other areas it is associated with an increase in precipitation. Salinity remains relatively high (34.6-34.7‰) in the south, where at this time the influx of saltier waters entering through the Korea Strait increases. In summer, the average salinity on the surface varies from 32.5‰ in the north of the Tatar Strait to 34.5‰ off the coast of the island. Honshu.
In the central and southern regions of the sea, precipitation significantly exceeds evaporation, which leads to desalination of surface waters. By autumn, the amount of precipitation decreases, the sea begins to cool, and therefore the salinity on the surface increases.
The vertical variation of salinity is generally characterized by small changes in its values along the depth.
In winter, most of the sea experiences a uniform salinity from surface to bottom, equal to approximately 34.1‰. Only in coastal waters is there a weakly expressed minimum salinity in the surface horizons, below which the salinity increases slightly and remains almost the same to the bottom. At this time of year, vertical changes in salinity in most of the sea do not exceed 0.6-0.7‰, and in its central part they do not reach
Spring-summer desalination of surface waters forms the main features of the summer vertical distribution of salinity.
In summer, minimal salinity is observed on the surface as a result of noticeable desalination of surface waters. In subsurface layers, salinity increases with depth, creating noticeable vertical salinity gradients. The maximum salinity at this time is observed at horizons of 50-100 m in the northern regions and at horizons of 500-1500 m in the southern regions. Below these layers, salinity decreases slightly and remains almost unchanged to the bottom, remaining within the range of 33.9-34.1‰. In summer, the salinity of deep waters is 0.1‰ less than in winter.
Water circulation and currents
The density of water in the Sea of Japan depends mainly on temperature. The highest density is observed in winter, and the lowest in summer. In the northwestern part of the sea the density is higher than in the southern and southeastern parts.
In winter, the surface density is quite uniform throughout the sea, especially in its northwestern part.
In spring, the uniformity of surface density values is disrupted due to different heating of the upper layer of water.
In summer, horizontal differences in surface density values are greatest. They are especially significant in the area of mixing waters with different characteristics. In winter, the density is approximately the same from surface to bottom in the northwestern part of the sea. In the southeastern regions, the density increases slightly at horizons of 50-100 m; deeper and to the bottom it increases very slightly. The maximum density is observed in March.
In summer in the northwest, the waters are noticeably interlayered in density. It is small on the surface, rises sharply at horizons of 50-100 m and increases more gradually deeper to the bottom. In the southwestern part of the sea, the density increases noticeably in the subsurface (up to 50 m) layers, at horizons of 100-150 m it is quite uniform, below the density increases slightly to the bottom. This transition occurs at horizons of 150-200 m in the northwest and at horizons of 300-400 m in the southeast of the sea.
In autumn, the density begins to level out, which means a transition to winter view density distribution with depth. Spring-summer density stratification determines a fairly stable state of the waters of the Sea of Japan, although it is expressed to varying degrees in different areas. In accordance with this, more or less favorable preconditions are created in the sea for the emergence and development of mixing.
Due to the predominance of winds of relatively low strength and their significant intensification during the passage of cyclones under conditions of water stratification in the north and northwest of the sea, wind mixing penetrates here to horizons of about 20 m. In the less stratified waters of the southern and southwestern regions, the wind mixes the upper layers to the horizons 25-30 m. In autumn, stratification decreases and winds increase, but at this time of year the thickness of the upper homogeneous layer increases due to density mixing.
Autumn-winter cooling, and in the north, ice formation, cause intense convection in the Sea of Japan. In its northern and northwestern parts, as a result of rapid autumn cooling of the surface, convective mixing develops, which covers deep layers within a short time. With the onset of ice formation, this process intensifies, and in December convection penetrates to the bottom. At great depths, it extends to horizons of 2000-3000 m. In the southern and southeastern regions of the sea, which are cooled to a lesser extent in autumn and winter, convection extends mainly to horizons of 200 m. In areas of sharp changes in depth, convection is enhanced by the sliding of water along the slopes, as a result of which density mixing penetrates to horizons of 300-400 m. Below mixing is limited by the density structure of water, and ventilation of the bottom layers occurs due to turbulence, vertical movements and other dynamic processes.
On the roadstead of Tokyo port
The nature of the circulation of sea waters is determined not only by the influence of the winds acting directly above the sea, but also by the circulation of the atmosphere over the northern part of the Pacific Ocean, since the strengthening or weakening of the influx of Pacific waters depends on it. In summer, the southeast monsoon increases water circulation due to the influx of large amounts of water. In winter, the persistent northwest monsoon prevents the flow of water into the sea through the Korea Strait, causing weakening water circulation.
Through the Korea Strait, the waters of the western branch of the Kuroshio, which passed through the Yellow Sea, enter the Sea of Japan and spread in a wide stream to the northeast along the Japanese islands. This flow is called the Tsushima Current. In the central part of the sea, the Yamato Rise divides the flow of Pacific waters into two branches, forming a divergence zone, which is especially pronounced in the summer. In this zone, deep waters rise. Having skirted the hill, both branches connect in an area located in the northwest of the Noto Peninsula.
At a latitude of 38-39°, a small flow separates from the northern branch of the Tsushima Current to the west, towards the Korea Strait, and turns into a countercurrent along the coast of the Korean Peninsula. The bulk of the Pacific waters are carried out from the Sea of Japan through the Sangarsky and La Perouse straits, while some of the waters, having reached the Tatar Strait, give rise to the cold Primorsky Current, moving south. South of Peter the Great Bay, the Primorsky Current turns east and merges with the northern branch of the Tsushima Current. A small part of the water continues to move south to Korea Bay, where it flows into the countercurrent formed by the waters of the Tsushima Current.
Thus, moving along the Japanese Islands from south to north, and along the coast of Primorye - from north to south, the waters of the Sea of Japan form a cyclonic gyre centered in the northwestern part of the sea. In the center of the gyre, rising waters are also possible.
In the Sea of Japan, two frontal zones are distinguished - the main polar front, formed by the warm and salty waters of the Tsushima Current and the cold, less salty waters of the Primorsky Current, and the secondary front, formed by the waters of the Primorsky Current and coastal waters, which in summer have more high temperature and lower salinity than the waters of the Primorsky Current. IN winter time the polar front runs slightly south of the parallel of 40° N, and near the Japanese Islands it runs approximately parallel to them almost to the northern tip of the island. Hokkaido. In summer, the location of the front is approximately the same, it only moves slightly to the south, and off the coast of Japan - to the west. The secondary front passes near the coast of Primorye, approximately parallel to them.
The tides in the Sea of Japan are quite distinct. They are created mainly by the Pacific tidal wave entering the sea through the Korea and Sangar Straits.
The sea experiences semi-diurnal, diurnal and mixed tides. In the Korea Strait and in the north of the Tatar Strait there are semi-diurnal tides, on the eastern coast of Korea, on the coast of Primorye, near the islands of Honshu and Hokkaido - diurnal tides, in Peter the Great and Korean Gulfs - mixed.
The nature of the tide corresponds to tidal currents. In open areas of the sea, semidiurnal tidal currents with speeds of 10-25 cm/s are mainly observed. Tidal currents in the straits are more complex, where they have very significant speeds. Thus, in the Sangar Strait, tidal current speeds reach 100-200 cm/s, in the La Perouse Strait - 50-100, in the Korea Strait - 40-60 cm/s.
The greatest level fluctuations are observed in the extreme southern and northern regions of the sea. At the southern entrance to the Korea Strait, the tide reaches 3 m. As you move north, it quickly decreases and already at Busan it does not exceed 1.5 m.
In the middle part of the sea the tides are low. Along the eastern coasts of the Korean Peninsula and Soviet Primorye, up to the entrance to the Tatar Strait, they are no more than 0.5 m. The tides are of the same magnitude off the western coasts of Honshu, Hokkaido and Southwestern Sakhalin. In the Tatar Strait, the tide height is 2.3-2.8 m. In the northern part of the Tatar Strait, the tide heights increase, which is determined by its funnel-shaped shape.
In addition to tidal fluctuations, seasonal level fluctuations are well expressed in the Sea of Japan. In summer (August - September) the maximum rise in level is observed on all shores of the sea; in winter and early spring (January - April) the minimum level is observed.
In the Sea of Japan, surge level fluctuations are observed. During the winter monsoon off the western coast of Japan, the level can rise by 20-25 cm, and off the mainland coast it can drop by the same amount. In summer, on the contrary, off the coast of North Korea and Primorye the level rises by 20-25 cm, and near Japanese shores decreases by the same amount.
Strong winds caused by the passage of cyclones and especially typhoons over the sea develop very significant waves, while monsoons cause less strong waves. In the northwestern part of the sea, northwestern waves predominate in autumn and winter, and eastern waves prevail in spring and summer. Most often, disturbances with a force of 1-3 points are observed, the frequency of which varies from 60 to 80% per year. In winter, strong waves prevail - 6 points or more, the frequency of which is about 10%.
In the southeastern part of the sea, thanks to the stable northwest monsoon, waves from the northwest and north develop in winter. In summer, weak, most often southwesterly, waves prevail. The largest waves have a height of 8-10 m, and during typhoons, the maximum waves reach a height of 12 m. Tsunami waves are observed in the Sea of Japan.
The northern and northwestern parts of the sea, adjacent to the mainland coast, are covered with ice annually for 4-5 months, the area of which occupies about 1/4 of the entire sea.
Ice cover
The appearance of ice in the Sea of Japan is possible as early as October, and the last ice lingers in the north sometimes until mid-June. Thus, the sea is completely ice-free only during the summer months - July, August and September.
The first ice in the sea forms in closed bays and bays of the mainland coast, for example in Sovetskaya Gavan Bay, De-Kastri and Olga Bays. In October - November, ice cover mainly develops within bays and bays, and from late November - early December, ice begins to form in the open sea.
At the end of December, ice formation in coastal and open sea areas extends to Peter the Great Bay.
Fast ice is not widespread in the Sea of Japan. It forms first in the bays of De-Kastri, Sovetskaya Gavan and Olga; in the bays of Peter the Great Bay and Posyet it appears after about a month.
Every year, only the northern bays of the mainland coast freeze completely. South of Sovetskaya Gavan, the fast ice in the bays is unstable and can break up repeatedly during the winter. In the western part of the sea, floating and stationary ice appears earlier than in the eastern part; it is more stable. This is explained by the fact that the western part of the sea in winter is under the predominant influence of cold and dry air masses spreading from the mainland. In the east of the sea, the influence of these masses weakens significantly, and at the same time the role of warm and humid marine air masses increases. The ice cover reaches its greatest development around mid-February. From February to May, conditions favorable for ice melting (in situ) are created throughout the sea. In the eastern part of the sea, ice melting “begins earlier and occurs more intensely than at the same latitudes in the west.
Ice cover in the Sea of Japan varies significantly from year to year. There may be cases when the ice cover in one winter is 2 times or more greater than the ice cover in another.
Economic importance
Inhabitants of the Sea of Japan
The fish population of the Sea of Japan includes 615 species. The main commercial species of the southern part of the sea include sardine, anchovy, mackerel, and horse mackerel. In the northern regions, the main fish caught are mussels, flounder, herring, greenling and salmon. In summer, tuna, hammerfish, and saury penetrate into the northern part of the sea. The leading place in the species composition of fish catches is occupied by pollock, sardine and anchovy.
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 water, spreading in a wide strip on the surface of the ocean and capturing a layer of water of varying depth. At greater depths and near the bottom, there are slower movements of water particles, most often in the opposite direction compared to surface currents, which is 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 of 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 tilt caused by changes in the distribution of 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. According to physical and chemical characteristics, for example, warm and cold. Moreover, the absolute value of temperature does not matter for the 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 the period of greatest development of the winter monsoon, blowing from the north or northwest, where Kuroshio is usually located, ships often note currents directed to the south. This indicates a strong dependence of the current on the monsoon winds that occur off the eastern coast of Asia. great strength and consistency.
The influence of Kuroshio on the climate of coastal countries of 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, 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 descends under the surface waters of the ocean and continues for another 370 km as 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 in 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- Nevelskogo has a maximum depth of 10 m, and 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 on the oceanography of the Bering, Okhotsk and Japan Seas (POI 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 up 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 of the Sea of Japan. Flowing through Korea Strait The subtropical waters of the Kuroshio branch throughout the year warm the southern regions of the sea and the 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.
In size it is inferior to the sea and, its area is up to 1,062 tons km2, and the deepest depression reaches up to 3,745 m. It is generally accepted that the average depth is 1,535 m. Large depths with a geographical location indicate that the sea belongs to the marginal oceanic seas.
There are medium and small islands in the sea. The most significant of them are Rishiri, Oshima, Sado, Momeron, Russian. Almost all the islands are located along the mainland in the eastern part.
The coastline is slightly indented, the outlines of Sakhalin Island are especially simple. with the Japanese Islands it has a more indented coastline. The main major seaports are Vostochny Port, Wonsan, Kholmsk, Vladivostok, Tsuruga, Chongjin.
Currents of the Sea of Japan
Tides in the Sea of Japan
Tides are expressed differently in different areas of the sea; they are especially pronounced in the summer and reach up to three meters in the Korea Strait. To the north, the tides decrease and do not exceed 1.5 m. This is explained by the fact that the bottom has a funnel shape. The greatest fluctuations are observed in the northern and southern extreme regions of the sea in the summer.
I offer you an interesting video “Parallel World - Sea of Japan” from the “Russian underwater expeditions” series.
—
The East Korean Current is a branch of the Tsushima Current along the coast of Korea. A feature of the current is its separation from the shore, which is usually noticeable at 38° N. This branch of the Tsushima Current is more powerful than the other two. Warm waters transported north through it meet cold waters and form the Subarctic Front. Numerous vortices and jets depart from this branch, so that the interaction of cold subarctic and warm subtropical does not occur along a narrow line, but in a large frontal zone. 80-90% of its waters return to the south in the form of a countercurrent and only a small part of them penetrates to the north and northeast (mainly through eddies and jets). The salinity and concentration of dissolved oxygen in the waters transported by the East Korean Current are similar to those of the Tsushima Current waters (34.10-34.40 ‰ and less than 5 ml/l, respectively). The temperature, both in summer and winter, never falls below 12 °C. The highest current speed values were noted in the zone located between the 4-8 °C isotherms at a horizon of 100 m (Tanioka K., 1968). The average speed of the current is 9 cm/s, and the average width of the stream is 30 miles. But the characteristics of the flow are variable: for example, the volumetric transport by the current varies from 0.3 to 3.2 light. It is believed that the current speed is higher in summer (47 cm/s) than in winter (17 cm/s), and interannual variability is greater than intraannual variability (Shuto K., 1982).
The Primorsky Current is a flow of cold desalinated waters along the coast of the continent from the northern part of the Tatar Strait to Peter the Great Bay. Its origins are unclear. The characteristics of the Primorsky Current and the characteristics of the waters carried by it have never been specifically studied. The characteristics of its waters according to different sources are very contradictory. The most reliable information is about salinity (always less than 34.00 ‰), since the waters of the Tatar Strait have always been characterized by low salinity and high concentration of dissolved oxygen (usually more than 6.0 ml/l). It was noted (Hidaka K.) that “the cold currents of the Sea of Japan are significantly weaker than the warm ones.” Due to the fact that in the Sea of Japan the warm currents themselves are rather weak, the Primorsky Current is most noticeable only in winter, when northern and northwestern winds prevail over Primorye. At this time, numerous jets move away from the current (Istoshin Yu.V., 1950).
The North Korean Current is a southward flow of cold input from Peter the Great Bay, at least to 38° N. latitude. Due to the fact that this current is artificially separated from the Primorsky current, the area of its formation is only conditionally assigned to the Peter the Great Gulf. Often this current is not particularly noticeable. The current is located in North Korea's exclusive economic zone, so special conditions oceanographic work led to its extremely low oceanographic knowledge. For these reasons, very little is known about this current. M. Uda noticed that the North Korean Current is stronger than the Primorsky Current. The width of this current, according to M. Uda’s calculations, is 100 km, the thickness of the layer it transports is 50 m, and the average speed is 25 cm/sec.
The Tsushima Current is a flow of warm and salty subtropical waters from the Tsushima Strait in the south to the middle of the Tatar Strait in the north. The warm waters of the Yellow Sea also take part in the formation of its waters, but it is usually considered only as a branch of the Kuroshio, separated from the main flow in the area of the island. Kyushu. Its waters differ from surrounding waters primarily in their high (more than 34.3 ‰) salinity. The core of the current is usually traced around the 100 m horizon. This current is weak compared to Kuroshio. His speed is, on average, 20 times less than Kuroshio's speed. The average transport (across the Tsushima Strait) is about 2 sv, but it is thought to vary throughout the year from a minimum (less than 1 sv) in February to a maximum in August (more than 5 sv). Due to its low speed, the current strongly meanders, separating warm eddies, branches and jets. Two main branches of the current are visible already in the strait. The transfer ratio in the western and eastern parts of the strait is, according to K. Naganuma, 3:1. Despite the fact that the current is sometimes presented as meandering, it is usually represented as consisting of two branches: along the coast of Japan (Tsushima Current), along the coast of Korea (East Korean Current). Sometimes another (nameless) branch is identified between them. Approximately at 38°N. the second branch breaks away from the shore. Despite the fact that the reason for the separation of the Kuroshio and the East Korean Current is the same (the uneven rotation of the Earth at different latitudes), the latitude of the separation of the East Korean Current exceeds the latitude of the Kuroshio separation by hundreds of kilometers. Flow branches do not always exist simultaneously. For example, in 1973, the first branch was observed only in the summer (from March to August), the second - from June to August, and only the third usually exists throughout the year (although seasons and years are known when it was absent). The first branch penetrates the sea only through the eastern part of the Tsushima Strait, and the other two - through the western. The temperature of the water carried by the current decreases from 28 °C in summer (14 °C in winter) in the Tsushima Strait to 17 °C (8 °C) in the Hokkaido region. The concentration of dissolved oxygen in the subtropical waters of the current never exceeds 5.0 ml/l, and the conditional density is 27.20.
The Sea of Japan is considered one of the largest and deepest seas in the world. It is a marginal sea of the Pacific Ocean.
Origin
The first information about this sea was received from Chinese sources in the 2nd century BC. Historically, it is believed that this reservoir was formed as a result of the melting of a glacier and rising water levels in the world's oceans.
Historical events
In the 14th-16th centuries, pirates seized power at sea. All maritime trade was under their control. From 1603 to 1867, the Sea of Japan was one of the busiest transport links and the main route of entry for Dutch and Korean embassies.
Sea of Japan on the map photo
The Sea of Japan witnessed the Russo-Japanese War (1901-1902). Today, the Sea of Japan is an important domestic and international transport artery.
Characteristic
Main characteristics of the Sea of Japan:
- Area 1,062,000 square km
- Average sea depth: 1536 m.
- Greatest depth: 3742 m.
- Salinity: 34-35 ‰.
- Length: from north to south 2,255 km, from west to east about 1,070 km.
- In winter, part of the Sea of Japan freezes - the Russian coastal side, but the ice can break up periodically;
- Average annual temperature: in the north 0-12C, in the south 17-26C.
shore of the Sea of Japan photo
Currents
The main current of the Sea of Japan is the Tsushima, whose width is approximately 200 km. This current contains surface and intermediate water masses. In addition, the following cold currents are observed in the Sea of Japan:
- Limanskoye, moving at low speed to the southwest;
- North Korean, going south;
- Coastal, or cold current, going to the central part.
Japanese Sea. Primorsky Krai photo
These cold currents form a counterclockwise circulation. The warm Kuroshio Current prevails in the southern part of the sea.
What rivers flow into
Few rivers flow into the Sea of Japan, most of them are mountainous. Let us note the largest of them:
- Partisan;
- Tumnin;
- Samarga;
- Rudnaya.
Where does the Sea of Japan flow into?
Sea waters enter through the straits:
- through the Nevelsky Strait to the Sea of Okhotsk;
- through the Sangar Strait to the Pacific Ocean;
- through the Korea Strait into the East China Sea.
Japanese Sea. storm photo
Climate
The climate of the sea is monsoon, temperate. The western and northern parts of the sea are much colder than the southern and eastern. The temperature difference reaches +27 C. Hurricanes and typhoons often pass over the sea surface.
Despite the fact that the sea is separated from the ocean by the Japanese islands and Sakhalin, storms and hurricanes often rage in the northern part of the sea, especially in autumn. Such exposure can last up to three days, and the waves reach 12 meters in height. The Siberian anticyclone brings such weather. For this reason, the Sea of Japan is not very calm for shipping.
Japanese Sea. port of Vladivostok photo
In November, the northern part of the sea is covered with ice, and in March-April the ice breaks up. In summer the weather is cloudy and weak monsoon winds from the southeast prevail.
Relief
The bottom topography of the Sea of Japan is divided into:
- the northern part (a wide trench that narrows and rises to the north);
- the central part (a deep closed basin, elongated in a northeast direction);
- the southern part (the terrain is complex, alternating shallow water with troughs).
The shores of this sea are mostly mountainous. Low-lying coastlines are extremely rare. The coastline is quite flat on Sakhalin. The shores of Primorye are more rugged.
underwater world of the Sea of Japan photo
Cities and ports
Let us note the more significant Russian port cities located in the Sea of Japan:
- Vladivostok;
- Nakhodka;
- Oriental;
- Sovetskaya Gavan;
- Vanino;
- Shakhtersk
Flora and fauna
Brown algae and kelp grow abundantly along the seashores. The Sea of Japan is very rich in fish fauna due to the abundance of oxygen and food. Approximately 610 species of fish live here. The main types of fish fauna are:
- In the southern part of the sea - anchovy, sardine, horse mackerel, mackerel.
- In the northern regions - flounder, herring, salmon, greenling, mussels, saury, hammerfish, tuna.
Fishing in the Sea of Japan lasts all year round. This region is home to 6 species of seals, 12 species of sharks that are not dangerous to humans, squid and octopuses.
Few people know the following interesting facts about the Sea of Japan:
- Residents of North Korea call this sea the Korean East Sea;
- Residents South Korea- Eastern Sea.
- Here you can meet representatives of 31 orders of fish out of 34 orders existing in the world;
- The Sea of Japan leads in fish diversity among all the seas of the Russian Federation;
- A small jellyfish lives in the algae of the sea, capable of infecting the central nervous system, and with repeated contact its poison can be fatal. There are no famous resorts here, but the Sea of Japan is very important for the trade and economy of several countries, including Russia.
