Sea of Okhotsk water temperature in summer. Physiographic conditions of the Sea of Okhotsk
This natural reservoir is considered one of the deepest and largest in Russia. The coolest Far Eastern sea is located between the Bering and Sea of Japan.
The Sea of Okhotsk separates the territories of the Russian Federation and Japan and represents the most important port point for our country.
After reading the information in the article, you can learn about the rich resources of the Sea of Okhotsk and the history of the formation of the reservoir.
About the name
Previously, the sea had other names: Kamchatka, Lamskoye, Hokkai among the Japanese.
The sea received its current name from the name of the Okhota River, which in turn comes from the Even word “okat”, which translates as “river”. The former name (Lamskoe) also came from the Even word “lam” (translated as “sea”). Japanese Hokkai literally means "North Sea". However, due to the fact that this Japanese name now refers to the North Atlantic Sea, its name was changed to Ohotsuku-kai, which is an adaptation of the Russian name to the norms of Japanese phonetics.
Geography
Before we move on to a description of the rich resources of the Sea of Okhotsk, let us briefly introduce its geographical location.
Located between the Bering and Sea of Japan, the body of water extends far into the mainland. The arc of the Kuril Islands separates the waters of the sea from the waters of the Pacific Ocean. The reservoir has for the most part natural boundaries, and its conditional boundaries are with the Sea of Japan.
The Kuril Islands, which are about 3 dozen small areas of land and separate the ocean from the sea, are located in a seismic zone due to the presence of a large number of volcanoes. In addition, the waters of these two natural reservoirs are separated by the island of Hokkaido and Kamchatka. The largest island in the Sea of Okhotsk is Sakhalin. The largest rivers flowing into the sea: Amur, Okhota, Bolshaya and Penzhina.
Description
The area of the sea is approximately 1603 thousand square meters. km, water volume - 1318 thousand cubic meters. km. The maximum depth is 3916 meters, the average is 821 m. The sea type is mixed, continental-marginal.
Several bays run along the fairly flat coastal border of the reservoir. The northern part of the coast is represented by many rocks and rather sharp cliffs. Storms are a frequent and quite common phenomenon for this sea.
The features of nature and all the resources of the Sea of Okhotsk are partly related to climate conditions and unusual terrain.
For the most part, the seashores are rocky and high. From the sea, from afar, on the horizon, they stand out as black stripes, framed on top by brownish green spots of sparse vegetation. Only in some places (the western coast of Kamchatka, the northern part of Sakhalin) the coastline is low-lying, fairly wide areas.
The bottom in some respects is similar to the bottom of the Sea of Japan: in many places there are hollows under the water, which indicate that the area of the present sea in the Quaternary period was above ocean level, and huge rivers - Penzhina and Amur - flowed in this place.
Sometimes during earthquakes, waves appear in the ocean reaching several tens of meters in height. One interesting historical fact is connected with this. In 1780, during an earthquake, one of these waves carried the ship “Natalia” deep into the island of Urup (300 meters from the shore), which remained on land. This fact is confirmed by a record preserved from those times.
Geologists believe that the territory of the eastern part of the sea is one of the most “turbulent” areas on the globe. And today quite large movements of the earth’s crust are taking place here. Underwater earthquakes and volcanic eruptions are often observed in this part of the ocean.
A little bit of history
The rich natural resources of the Sea of Okhotsk began to attract the attention of people from its very discovery, which occurred during the first campaigns of the Cossacks to the Pacific Ocean through Siberia. It was then called the Sea of Lama. Then, after the discovery of Kamchatka, trips by sea and shore to this rich peninsula and to the mouth of the river. Penzhins became more frequent. In those days, the sea already bore the names Penzhinskoye and Kamchatka.
Having left Yakutsk, the Cossacks moved east not straight through the taiga and mountains, but along winding rivers and channels between them. Such a caravan trail eventually led them to a river called Okhota, and along it they moved to the seashore. That is why this reservoir was named Okhotsk. Since then, many significant and important large centers have arisen on the sea coast. The name that has been preserved since then testifies to the important historical role of the port and the river, from which people began to develop this huge, rich sea area.
Features of nature
The natural resources of the Sea of Okhotsk are quite attractive. This is especially true for the areas of the Kuril Islands. This is a very special world, consisting of a total of 30 large and small islands. This range also includes rocks of volcanic origin. Today there are active volcanoes on the islands (about 30), which clearly indicates that the bowels of the earth are unquiet here and now.
Some islands have underground hot springs (temperatures up to 30-70°C), many of which have healing properties.
The climatic conditions for life on the Kuril Islands (especially in the northern part) are very harsh. Fogs linger here for a long time, and in winter, severe storms often occur.
Rivers
Many rivers, mostly small, flow into the Sea of Okhotsk. This is the reason for the relatively small continental flow (about 600 cubic km per year) of water into it, with about 65% of it belonging to the Amur River.
Other relatively large rivers are the Penzhina, Uda, Okhota, and Bolshaya (in Kamchatka), which carry a much smaller volume of fresh water into the sea. Water flows in to a greater extent in spring and early summer.
Fauna
The biological resources of the Sea of Okhotsk are very diverse. This is the most biologically productive sea in Russia. It provides 40% of domestic and more than half of the Far Eastern catches of fish, crustaceans and mollusks. At the same time, it is believed that the biological potential of the sea is currently underutilized.
A huge variety of depths and bottom topography, hydrological and climatic conditions in certain parts of the sea, a good supply of fish food - all this determined the richness of the ichthyofauna of these places. The northern part of the sea contains 123 species of fish in its waters, the southern part - 300 species. Approximately 85 species are endemic. This sea is a real paradise for sea fishing lovers.
Fishing, seafood production and the production of salmon caviar are actively developing in the sea. Inhabitants of the sea waters of this region: pink salmon, chum salmon, cod, sockeye salmon, flounder, coho salmon, pollock, herring, navaga, chinook salmon, squid, crabs. On the Shantar Islands there is hunting (limited) for seals, and the hunting of kelp, mollusks and sea urchins is also becoming popular.
Of the animals of particular commercial value, beluga whales, seals and seals are of particular commercial value.
Flora
The resources of the Sea of Okhotsk are inexhaustible. The flora of the reservoir: Arctic species predominate in the northern part, and species from the temperate region predominate in the southern part. Plankton (larvae, mollusks, crustaceans, etc.) provide abundant food for fish throughout the year. The sea's phytoplankton are dominated by diatoms, and the bottom flora contains many species of red, brown and green algae, as well as extensive meadows of sea grass. In total, the coastal flora of the Sea of Okhotsk includes about 300 species of vegetation.
In comparison with the Bering Sea, the bottom fauna here is more diverse, and in comparison with the Japanese Sea, it is less rich. The main feeding grounds for deep-sea fish are the northern shallow waters, as well as the eastern Sakhalin and western Kamchatka shelves.
Mineral resources
The mineral resources of the Sea of Okhotsk are especially rich. Only sea water contains almost all the elements of D.I. Mendeleev’s table.
The seabed has exceptional reserves of globigerine and diamondite silts, consisting mainly of shells of unicellular tiny algae and protozoa. Silts are valuable raw materials for the production of insulating building materials and high quality cement.
The sea shelf is also promising for searching for hydrocarbon deposits. The rivers of the Aldan-Okhotsk watershed and the lower reaches of the Amur have been famous since ancient times for their placers of valuable metals, which suggests that there is a possibility of underwater ore deposits being found in the sea. There may be many still undiscovered raw material resources in the Sea of Okhotsk.
It is known that the lower shelf horizons and the part of the continental slope bordering them are enriched in phosphorite nodules. There is another more realistic prospect - the extraction of rare elements contained in the bone remains of mammals and fish, and such accumulations are found in the deep-sea sediments of the South Okhotsk basin.
We cannot remain silent about amber. The very first discoveries of this mineral on the eastern coast of Sakhalin date back to the mid-19th century. At that time, representatives of the Amur expedition were working here. It should be noted that Sakhalin amber is very beautiful - it is perfectly polished, cherry-red and is quite highly valued by specialists. The largest pieces of fossil wood resin (up to 0.5 kg) were discovered by geologists near the village of Ostromysovsky. Amber is also found in the oldest deposits of the Taygonos Peninsula, as well as in Kamchatka.
Conclusion
In short, the resources of the Sea of Okhotsk are extremely rich and diverse, it is impossible to list them all, much less describe them.
Today, the importance of the Sea of Okhotsk in the national economy is determined by the use of its rich natural resources and maritime transport. The main wealth of this sea is game animals, primarily fish. However, even today, a fairly high level of danger of pollution of sea fishing zones with oil products as a result of discharges of oil-containing water by fishing vessels creates a situation that requires certain measures to increase the level of environmental safety of the work being carried out.
The Sea of Okhotsk is part of the Pacific Ocean, separated from it by the Kamchatka Peninsula, the Kuril Islands and the island of Hokkaido. The sea washes the shores of Russia and Japan.
Area - 1603 thousand km². Average depth - 1780 m, maximum depth - 3916 m.
Ideas about the cyclonic nature of the general circulation of the sea developed at the end of the 19th - beginning of the 20th centuries. mainly based on indirect data (Fig. 2.9). Due to the lack of direct measurements of currents, the main research method remains calculations on mathematical models using the dynamic method, for example (K.V. Moroshkin 1966).
The results of current measurements in the Sea of Okhotsk confirm the presence of cyclonic circulation (Rogachev K.A. 2001). Currents were measured for 3 months at Kashevarova on the horizon 140 m at a distance of 14 m from the bottom. (Fig. 2.9 v. 1.) The currents are unidirectional (as in the Middle Caspian) from north to south (Fig. 2.10 a). The figure shows that the currents change with a high frequency, and the constant component is also large (45-120 cm/s).
It should be noted that there are 4 different opinions regarding the nature of the currents observed on the Kashevarov Bank.
The author himself (Rogachev 2001) believes that high-frequency currents are tidal currents. Low frequency currents o are formed as a result of the interaction of two tidal harmonics with close periods of 25.82 hours. and 23.93h. Modulations are formed with periods of 13.66 days (I - II, II - III, III - IV, etc., Fig. 2.10 a, b).
V.N. Zyryanov (1985) believes that the Kashevarov bank is an example of a topographic vortex system. The controlling mechanism of water dynamics in the bank area is a vortex torus formed by the anticyclonic Taylor-Hogg vortex and its cyclonic satellite.
Rice. 2.9. Scheme of large-scale currents in the Sea of Okhotsk. Sea currents, represented as streamlines, are indicated by a smooth thick line with arrows. 1-4 – buoy placement points. (Bondarenko A.L., Rudykh N.I. 2003). The dotted line is the estimated large-scale circulation contour, coinciding with the isobath line.
A.L. Bondarenko (Bondarenko et al. 2004) uses a filter to identify the moving equilibrium average with an averaging period of 48 hours. Large-scale currents U (indicated in the figure by a thick line) and currents of the tidal waves themselves V (Fig. 2.10b). A comparison of Figures 2.10a and 2.10b shows that at moments I, II, III, etc., the amplitudes of velocity fluctuations of the wave currents themselves are minimal; at moments I ′, II ′, III ′, etc. – maximum.
The wave transfer of U changes with the same period of 13.66 days, and is proportional to the values amplitudes of fluctuations in the speed of tidal wave currents V approximately according to equation
U=3V
The maximum velocities of tidal wave currents V are 35 cm/s, and the maximum velocities of large-scale circulation currents U are 120 cm/s. (Bondarenko and etc. 2004) concludes: tidal waves V, as well as continental shelf waves, are capable of creating wave transport at high speeds.
In the work (Shchevyev 2005) he doubts the possibility of waves with an amplitude of up to 35 cm/s, oscillations around the equilibrium position, creating unidirectional transfer of water masses with maximum speeds of up to 120 cm/s. Another interpretation of this unique experiment is being considered.
Rice. 2.10. Currents in the Sea of Okhotsk on the Kashevarov Bank (Rogachev K. A. 2001).
In addition to the measurement results (Fig. 2.10), a spectral analysis of high-frequency oscillations, which appeared to be tidal, was performed. He showed that these are inertial oscillations with a period (13.63 - 15.38 hours) and two harmonics (Fig. 2.11).
Rice. 2.11. Spectral density function of currents on the Kashevarov bank. (Built by Trubkin I.P., GOIN).
It is more plausible to explain the observational results (Fig. 2.10.) as follows: in all internal and marginal seas of the northern hemisphere there are long-period wave currents running around the basin cyclonically.
In Fig. 2.10a shows the result of measuring the total flow, n.ch. and v.ch. The resulting movement of these currents is the large-scale cyclonic circulation. Movement long-period wave flow is deflected into the Coriolis force field. Inertial waves are formed (Fig. 2.10.b).
The sea has predominantly natural boundaries and is only separated from the waters by conventional boundaries. The Sea of Okhotsk is a fairly large and deep sea in our country. Its area is about 1603 thousand km2, the volume of water is 1318 thousand km3. The average depth of this sea is 821 m, the maximum depth is 3916 m. According to its characteristics, this sea is a marginal sea of a mixed continental-marginal type.
There are few islands in the waters of the Sea of Okhotsk, among which the largest is. The Kuril ridge consists of 30 different in size. Their location is seismically active. There are over 30 active and 70 extinct ones here. Zones of seismic activity can be located both on islands and under water. If the epicenter is under water, then huge ones rise.
The coastline of the Sea of Okhotsk, despite its considerable length, is quite equal. There are many large bays along the coastline: Aniva, Terpeniya, Sakhalinsky, Academy, Tugursky, Ayan and Shelikhova. There are also several lips: Tauiskaya, Gizhiginskaya and Penzhinskaya.
Sea of Okhotsk
The bottom represents a wide range of different underwater elevations. The northern part of the sea is located on a continental shelf, which is a continuation of the land. In the western zone of the sea there is a sandbank of Sakhalin, located near the island. In the east of the Sea of Okhotsk is Kamchatka. Only a small part is located in the shelf zone. A significant part of the water expanses is located on the continental slope. The sea depth here varies from 200 m to 1500 m.
The southern edge of the sea is the deepest zone, the maximum depth here is more than 2500 m. This part of the sea is a kind of bed, which is located along the Kuril Islands. The southwestern part of the sea is characterized by deep depressions and slopes, which is not typical for the northeastern part.
In the central zone of the sea there are two hills: the Academy of Sciences of the USSR and the Institute of Oceanology. These hills divide the underwater sea space into 3 basins. The first basin is the northeastern depression of TINRO, which is located west of Kamchatka. This depression is characterized by shallow depths, about 850 m. The bottom has. The second basin is the Deryugin depression, located east of Sakhalin, the water depth here reaches 1700 m. The bottom is a plain, the edges of which are slightly raised. The third basin is the Kuril basin. It is the deepest (about 3300 m). is a plain that extends for 120 miles in the western part, and 600 miles in the northeastern part.
The Sea of Okhotsk is influenced by. The main source of cold air is located in the west. This is due to the fact that the western part of the sea is strongly cut into the mainland and is located not far from the Asian pole of cold. From the east, the relatively high mountain ranges of Kamchatka impede the advance of warm Pacific waves. The greatest amount of heat comes from the waters of the Pacific Ocean and the Sea of Japan through the southern and southeastern borders. But the influence of cold air masses dominates over warm air masses, so in general the Sea of Okhotsk is quite harsh. The Sea of Okhotsk is the coldest compared to the Sea of Japan.
Sea of Okhotsk
During the cold period (which lasts from October to April), the Siberian and Aleutian lows have a significant influence on the sea. As a result, winds from the northern and northwestern directions predominate in the vastness of the Sea of Okhotsk. The power of these winds often reaches storm force. Particularly strong winds are observed in January and February. Their average speed is about 10 – 11 m/s.
In winter, the cold Asian monsoon contributes to a strong depression in the northern and northwestern parts of the sea. In January, when the temperature reaches its minimum limit, on average the air cools to – 20 – 25 °C in the northwestern part of the sea, to – 10 – 15 °C in the central part and to –5 – 6 °C in the southeastern part. The last zone is influenced by warm Pacific air.
In autumn and winter, the sea is influenced by continental influences. This leads to increased winds and, in some cases, colder temperatures. In general, it can be characterized as clear with reduced. These climatic features are influenced by cold Asian air. In April–May, the Siberian anticyclone ceases to operate, and the impact of the Honolulu maximum intensifies. In this regard, during the warm period, small southeast winds are observed, the speed of which rarely exceeds 6 - 7 m/s.
In summer, different temperatures are observed depending on. In August, the highest temperature is recorded in the southern part of the sea, it is +18°C. In the central part of the sea the temperature drops to 12 – 14°C. The northeast has the coldest summer, the average temperature does not exceed 10–10.5°C. During this period, the southern part of the sea is subject to numerous oceanic cyclones, due to which the wind strength increases, and storms rage for 5–8 days.
Sea of Okhotsk
A large number of rivers carry their waters into the Sea of Okhotsk, but they are all mostly small. In this regard, it is small, it is about 600 km 3 during the year. , Penzhina, Okhota, Bolshaya - the largest ones flowing into the Sea of Okhotsk. Fresh waters have little impact on the sea. The waters of the Sea of Japan and the Pacific Ocean are of great importance for the Sea of Okhotsk.
The Sea of Okhotsk protrudes quite deeply into the land and extends noticeably from southwest to northeast. It has shorelines almost everywhere. It is separated from the Sea of Japan by about. Sakhalin and the conventional lines of Cape Sushchev - Cape Tyk (Nevelskoy Strait), and in the La Perouse Strait - Cape Soya - Cape Crillon. The southeastern border of the sea goes from Cape Nosappu (Hokkaido Island) and through the Kuril Islands to Cape Lopatka (Kamchatka Peninsula).
The Sea of Okhotsk is one of the largest and deepest seas in the world. Its area is 1,603 thousand km 2, volume - 1,316 thousand km 3, average depth - 821 m, greatest depth - 3,521 m.
The Sea of Okhotsk belongs to the marginal seas of the mixed continental-ocean type. It is separated from the Pacific Ocean by the Kuril ridge, which has about 30 large and many small islands and rocks. The Kuril Islands are located in a belt of seismic activity, which includes more than 30 active and 70 extinct volcanoes. Seismic activity occurs on the islands and underwater. In the latter case, tsunami waves are often formed. In the sea there is a group of Shantarsky islands, the Spafaryev, Zavyalov, Yamsky islands and the small island of Jonah - the only one of all that is remote from the coast. Although the coastline is long, it is relatively weakly indented. At the same time, it forms several large bays (Aniva, Terpeniya, Sakhalinsky, Akademii, Tugursky, Ayan, Shelikhova) and bays (Udskaya, Tauyskaya, Gizhiginskaya and Penzhinskaya).
The Nevelskoy and La Perouse straits are relatively narrow and shallow. The width of the Nevelskoy Strait (between capes Lazarev and Pogibi) is only about 7 km. The width of the La Perouse Strait is 43-186 km, depth is 53-118 m.
The total width of the Kuril Straits is about 500 km, and the maximum depth of the deepest of them, the Bussol Strait, exceeds 2300 m. Thus, the possibility of water exchange between the Seas of Japan and the Sea of Okhotsk is incomparably less than between the Sea of Okhotsk and the Pacific Ocean.
However, even the depth of the deepest of the Kuril Straits is significantly less than the maximum depth of the sea, and therefore the Kuril ridge is a huge threshold that fences off the sea depression from the ocean.
The most important for water exchange with the ocean are the Bussol and Krusenstern straits, since they have the largest area and depth. The depth of the Bussol Strait was indicated above, and the depth of the Kruzenshtern Strait is 1920 m. Of less importance are the Frieza, Fourth Kurilsky, Rikord and Nadezhda straits, whose depths are more than 500 m. The depths of the remaining straits generally do not exceed 200 m, and their areas are insignificant.
On distant shores
The shores of the Sea of Okhotsk in different areas belong to different geomorphological types. For the most part, these are abrasive shores modified by the sea, and only in Kamchatka and Sakhalin are there accumulative shores. The sea is mostly surrounded by high and steep shores. In the north and northwest, rocky ledges descend directly to the sea. Along the Sakhalin Bay the shores are low. The southeastern coast of Sakhalin is low, and the northeastern coast is low. The shores of the Kuril Islands are very steep. The northeastern coast of Hokkaido is predominantly low-lying. The coast of the southern part of Western Kamchatka has the same character, but the shores of its northern part rise somewhat.
Shores of the Sea of Okhotsk
Bottom relief
The bottom topography of the Sea of Okhotsk is varied. The northern part of the sea is a continental shelf - an underwater continuation of the Asian continent. The width of the continental shelf in the area of the Ayano-Okhotsk coast is approximately 185 km, in the area of Udskaya Bay - 260 km. Between the meridians of Okhotsk and Magadan, the width of the shoal increases to 370 km. On the western edge of the sea basin is the island sandbank of Sakhalin, on the east - the sandbank of Kamchatka. The shelf occupies about 22% of the bottom area. The rest, most (about 70%) of the sea is located within the continental slope (from 200 to 1500 m), on which individual underwater hills, depressions and trenches are distinguished.
The deepest, southern part of the sea (more than 2500 m), which is a section of the bed, occupies 8% of the total area of the sea. It stretches as a strip along the Kuril Islands and gradually narrows from 200 km against the island. Iturup up to 80 km against the Krusenstern Strait. Great depths and significant bottom slopes distinguish the southwestern part of the sea from the northeastern part, which lies on the continental shallows.
Of the large elements of the bottom relief of the central part of the sea, two underwater hills stand out - the Academy of Sciences and the Institute of Oceanology. Together with the protrusion of the continental slope, they divide the sea basin into three basins: the northeastern - TINRO depression, the northwestern - Deryugin depression and the southern deep-sea - Kuril depression. The depressions are connected by gutters: Makarov, P. Schmidt and Lebed. To the northeast of the TINRO depression, the Shelikhov Bay trench extends.
The deepest depression is TINRO, located west of Kamchatka. Its bottom is a plain lying at a depth of about 850 m, with a maximum depth of 990 m.
The Deryugin Depression is located east of the underwater base of Sakhalin. Its bottom is a flat plain, raised at the edges, lying on average at a depth of 1700 m, the maximum depth of the depression is 1744 m.
The Kuril Depression is the deepest. This is a huge flat plain lying at a depth of about 3300 m. Its width in the western part is approximately 212 km, and its length in the northeast direction is about 870 km.
Bottom topography and currents of the Sea of Okhotsk
Currents
Under the influence of winds and the influx of water through the Kuril Straits, the characteristic features of the system of non-periodic currents of the Sea of Okhotsk are formed. The main one is a cyclonic system of currents, covering almost the entire sea. It is caused by the predominance of cyclonic atmospheric circulation over the sea and the adjacent part of the Pacific Ocean. In addition, stable anticyclonic gyres can be traced in the sea: to the west of the southern tip of Kamchatka (approximately between 50-52° N and 155-156° E); above the TINRO depression (55-57° N and 150-154° E); in the area of the Southern Basin (45-47° N and 144-148° E). In addition, a vast area of cyclonic water circulation is observed in the central part of the sea (47-53° N and 144-154° E), and the cyclonic circulation is to the east and northeast of the northern tip of the island. Sakhalin (54-56° N and 143-149° E).
Strong currents move around the sea along the coastline counterclockwise: the warm Kamchatka Current, directed north into Shelikhov Bay; flow of a western and then southwestern direction along the northern and northwestern shores of the sea; the stable East Sakhalin Current going south, and the rather strong Soya Current entering the Sea of Okhotsk through the La Perouse Strait.
On the southeastern periphery of the cyclonic circulation of the central part of the sea, a branch of the Northeast Current is distinguished, opposite in direction to the Kuril Current in the Pacific Ocean. As a result of the existence of these flows, stable areas of convergence of currents are formed in some of the Kuril straits, which leads to lowering of waters and has a significant impact on the distribution of oceanological characteristics not only in the straits, but also in the sea itself. And finally, another feature of the circulation of the waters of the Sea of Okhotsk is two-way stable currents in most of the Kuril Straits.
Surface currents on the surface of the Sea of Okhotsk are most intense off the western coast of Kamchatka (11-20 cm/s), in the Sakhalin Gulf (30-45 cm/s), in the Kuril Straits (15-40 cm/s), over the Southern Basin ( 11-20 cm/s) and during the Soya (up to 50-90 cm/s). In the central part of the cyclonic region, the intensity of horizontal transport is much less than at its periphery. In the central part of the sea, velocities vary from 2 to 10 cm/s, with the predominant velocities being less than 5 cm/s. A similar picture is observed in Shelikhov Bay: fairly strong currents off the coast (up to 20-30 cm/s) and low speeds in the central part of the cyclonic gyre.
In the Sea of Okhotsk, various types of periodic tidal currents are well expressed: semidiurnal, diurnal and mixed with a predominance of semidiurnal or diurnal components. Tidal current speeds range from a few centimeters to 4 m/s. Far from the coast, current speeds are low - 5-10 cm/s. In straits, bays and off the coast, their speeds increase significantly. For example, in the Kuril Straits, current speeds reach 2-4 m/s.
The tides of the Sea of Okhotsk are very complex. The tidal wave enters from the south and southeast from the Pacific Ocean. The semidiurnal wave moves north, and at the 50° parallel it divides into two parts: the western one turns northwest, and the eastern one moves toward Shelikhov Bay. The daily wave also moves north, but at the latitude of the northern tip of Sakhalin it is divided into two parts: one enters Shelikhov Bay, the other reaches the northwestern coast.
Diurnal tides are the most widespread in the Sea of Okhotsk. They are developed in the Amur Estuary, Sakhalin Bay, on the coast of the Kuril Islands, off the western coast of Kamchatka and in the Gulf of Penzhina. Mixed tides are observed on the northern and northwestern coasts of the sea and in the area of the Shantar Islands.
The highest tides (up to 13 m) were recorded in Penzhinskaya Bay (Cape Astronomichesky). In the area of the Shantar Islands, the tide exceeds 7 m. The tides are significant in the Sakhalin Bay and in the Kuril Straits. In the northern part of the sea their size reaches 5 m.
Fur seal rookery
The lowest tides were observed off the eastern coast of Sakhalin, in the area of the La Perouse Strait. In the southern part of the sea, the tides are 0.8-2.5 m.
In general, tidal level fluctuations in the Sea of Okhotsk are very significant and have a significant impact on its hydrological regime, especially in the coastal zone.
In addition to tidal fluctuations, surge level fluctuations are also well developed here. They occur mainly when deep cyclones pass over the sea. Surge increases in level reach 1.5-2 m. The largest surges are noted on the coast of Kamchatka and in Terpeniya Bay.
The considerable size and great depths of the Sea of Okhotsk, frequent and strong winds above it determine the development of large waves here. The sea is especially rough in the fall, and in ice-free areas even in winter. These seasons account for 55-70% of storm waves, including those with wave heights of 4-6 m, and the highest wave heights reach 10-11 m. The most turbulent are the southern and south-eastern regions of the sea, where the average frequency of storm waves is 35 -40%, and in the northwestern part it decreases to 25-30%. When the waves are strong, a crowd forms in the straits between the Shantar Islands.
Climate
The Sea of Okhotsk is located in the monsoon climate zone of temperate latitudes. A significant part of the sea in the west extends deep into the mainland and lies relatively close to the cold pole of the Asian landmass, so the main source of cold for the Sea of Okhotsk is located to the west of it. The relatively high ridges of Kamchatka make it difficult for warm Pacific air to penetrate. Only in the southeast and south is the sea open to the Pacific Ocean and the Sea of Japan, from where a significant amount of heat enters it. However, the influence of cooling factors is stronger than warming ones, so the Sea of Okhotsk is generally cold. At the same time, due to the large meridional extent, significant differences in synoptic conditions and meteorological conditions arise here. In the cold part of the year (from October to April), the sea is affected by the Siberian Anticyclone and the Aleutian Low. The influence of the latter extends mainly to the southeastern part of the sea. This distribution of large-scale pressure systems causes strong, sustained northwest and northerly winds, often reaching gale force. Little wind and calm are almost completely absent, especially in January and February. In winter, the wind speed is usually 10-11 m/s.
The dry and cold Asian winter monsoon significantly cools the air over the northern and northwestern regions of the sea. In the coldest month - January - the average air temperature in the north-west of the sea is -20 - 25°, in the central regions -10-15°, and in the south-eastern part of the sea it is -5 - 6°.
In autumn-winter, cyclones of predominantly continental origin enter the sea. They bring with them increased wind, sometimes a decrease in air temperature, but the weather remains clear and dry, as continental air arrives from the cooled mainland. In March - April, a restructuring of large-scale pressure fields occurs. The Siberian anticyclone is collapsing, and the Hawaiian high is intensifying. As a result, during the warm season (from May to October), the Sea of Okhotsk is influenced by the Hawaiian High and the low pressure area located over Eastern Siberia. At this time, weak south-easterly winds prevail over the sea. Their speed usually does not exceed 6-7 m/s. These winds are most common in June and July, although stronger northwest and northerly winds are sometimes observed during these months. In general, the Pacific (summer) monsoon is weaker than the Asian (winter) monsoon, since in the warm season the horizontal pressure gradients are smoothed out.
In summer, the average monthly air temperature in August decreases from the southwest (from 18°) to the northeast (to 10-10.5°).
In the warm season, tropical cyclones - typhoons - quite often pass over the southern part of the sea. They are associated with increased winds to storm force, which can last up to 5-8 days. The predominance of south-eastern winds in the spring-summer season leads to significant cloudiness, precipitation, and fog.
Monsoon winds and stronger winter cooling of the western part of the Sea of Okhotsk compared to the eastern are important climatic features of this sea.
Quite a lot of mostly small rivers flow into the Sea of Okhotsk, therefore, despite the significant volume of its waters, the continental flow is relatively small. It is approximately 600 km 3 /year, with about 65% of the flow coming from the Amur. Other relatively large rivers - Penzhina, Okhota, Uda, Bolshaya (in Kamchatka) - bring significantly less fresh water to the sea. Runoff occurs mainly in spring and early summer. At this time, its greatest influence is felt mainly in the coastal zone, near the mouths of large rivers.
Hydrology and water circulation
Geographical location, large length along the meridian, monsoon wind changes and good communication between the sea and the Pacific Ocean through the Kuril Straits are the main natural factors that most significantly influence the formation of the hydrological conditions of the Sea of Okhotsk. The amounts of heat inflow and outflow into the sea are determined mainly by the rational heating and cooling of the sea. The heat brought by Pacific waters is of subordinate importance. However, for the water balance of the sea, the arrival and flow of water through the Kuril Straits plays a decisive role.
The flow of surface Pacific waters into the Sea of Okhotsk occurs mainly through the northern straits, in particular through the First Kuril Strait. In the straits of the middle part of the ridge, both the influx of Pacific waters and the outflow of Okhotsk waters are observed. Thus, in the surface layers of the Third and Fourth Straits, apparently, there is a flow of water from the Sea of Okhotsk, in the bottom layers there is an influx, and in the Bussol Strait it’s the other way around: in the surface layers there is an influx, in the deep layers there is a runoff. In the southern part of the ridge, mainly through the Ekaterina and Frieze straits, water predominantly drains from the Sea of Okhotsk. The intensity of water exchange through the straits can vary significantly.
In the upper layers of the southern part of the Kuril ridge, the flow of Sea of Okhotsk waters predominates, and in the upper layers of the northern part of the ridge, the influx of Pacific waters occurs. In the deep layers, the influx of Pacific waters predominates.
Water temperature and salinity
The influx of Pacific waters significantly affects the distribution of temperature, salinity, structure formation and general circulation of waters in the Sea of Okhotsk. It is characterized by a subarctic water structure, in which cold and warm intermediate layers are well defined in summer. A more detailed study of the subarctic structure in this sea showed that there are Sea of Okhotsk, Pacific and Kuril varieties of the subarctic water structure. Although they have the same vertical structure, they have quantitative differences in the characteristics of water masses.
The following water masses are distinguished in the Sea of Okhotsk:
surface water mass that has spring, summer and autumn modifications. It is a thin heated layer 15-30 m thick, which limits the upper maximum of stability, determined mainly by temperature. This water mass is characterized by temperature and salinity values corresponding to each season;
The Sea of Okhotsk water mass is formed in winter from surface water and in spring, summer and autumn appears in the form of a cold intermediate layer lying between horizons of 40-150 m. This water mass is characterized by a fairly uniform salinity (31-32.9‰) and varying temperatures. In most of the sea its temperature is below 0° and reaches -1.7°, and in the area of the Kuril Straits it is above 1°;
The intermediate water mass is formed mainly due to the descent of water along underwater slopes, within the sea, ranging from 100-150 to 400-700 m, and is characterized by a temperature of 1.5° and a salinity of 33.7‰. This water mass is distributed almost everywhere, except for the northern part of the sea, Shelikhov Bay and some areas along the coast of Sakhalin, where the Sea of Okhotsk water mass reaches the bottom. The thickness of the layer of intermediate water mass decreases from south to north;
The deep Pacific water mass is the water of the lower part of the warm layer of the Pacific Ocean, entering the Sea of Okhotsk at horizons below 800-1000 m, i.e. below the depth of the waters descending in the straits, and in the sea it appears in the form of a warm intermediate layer. This water mass is located at horizons of 600-1350 m, has a temperature of 2.3° and a salinity of 34.3‰. However, its characteristics change in space. The highest values of temperature and salinity are observed in the northeastern and partly in the northwestern regions, which is associated here with rising waters, and the lowest values of the characteristics are characteristic of the western and southern regions, where subsidence of waters occurs.
The water mass of the southern basin is of Pacific origin and represents the deep water of the northwestern part of the Pacific Ocean near the horizon of 2300 m, i.e. horizon corresponding to the maximum depth of the threshold in the Kuril Straits, located in the Bussol Strait. This water mass fills the basin from a horizon of 1350 m to the bottom and is characterized by a temperature of 1.85° and a salinity of 34.7‰, which vary only slightly with depth.
Among the identified water masses, the Sea of Okhotsk and the deep Pacific are the main ones; they differ from each other not only in thermohaline, but also in hydrochemical and biological parameters.
The water temperature at the sea surface decreases from south to north. In winter, almost everywhere the surface layers are cooled to a freezing temperature of –1.5-1.8°. Only in the southeastern part of the sea does it remain around 0°, and near the northern Kuril Straits, under the influence of Pacific waters, the water temperature reaches 1-2°.
Spring warming at the beginning of the season mainly leads to the melting of ice, only towards the end of it does the water temperature begin to rise.
In summer, the distribution of water temperature on the sea surface is quite varied. In August, the waters adjacent to the island are warmest (up to 18-19°). Hokkaido. In the central regions of the sea, the water temperature is 11-12°. The coldest surface waters are observed near the island. Iona, near Cape Pyagin and near the Krusenstern Strait. In these areas, the water temperature is between 6-7°. The formation of local centers of increased and decreased water temperatures on the surface is mainly associated with the redistribution of heat by currents.
The vertical distribution of water temperature varies from season to season and from place to place. In the cold season, temperature changes with depth are less complex and varied than in warm seasons.
In winter, in the northern and central regions of the sea, water cooling extends to horizons of 500-600 m. The water temperature is relatively uniform and varies from -1.5-1.7° on the surface to -0.25° at horizons of 500-600 m, deeper rises to 1-0°, in the southern part of the sea and near the Kuril Straits the water temperature from 2.5-3° on the surface drops to 1-1.4° at horizons of 300-400 m and then gradually rises to 1.9-2 .4° in the bottom layer.
In summer, surface waters are heated to a temperature of 10-12°. In the subsurface layers, the water temperature is slightly lower than on the surface. A sharp drop in temperature to -1 - 1.2° is observed between horizons of 50-75 m, deeper, to horizons of 150-200 m, the temperature quickly rises to 0.5 - 1°, and then it rises more smoothly, and at horizons of 200 - 250 m is equal to 1.5 - 2°. Further, the water temperature remains almost unchanged until the bottom. In the southern and southeastern parts of the sea, along the Kuril Islands, the water temperature from 10 - 14° on the surface drops to 3 - 8° at a horizon of 25 m, then to 1.6-2.4° at a horizon of 100 m and to 1 ,4-2° at the bottom. The vertical temperature distribution in summer is characterized by a cold intermediate layer. In the northern and central regions of the sea the temperature is negative, and only near the Kuril Straits it has positive values. In different areas of the sea, the depth of the cold intermediate layer is different and varies from year to year.
The distribution of salinity in the Sea of Okhotsk varies relatively little between seasons. Salinity increases in the eastern part, which is under the influence of Pacific waters, and decreases in the western part, desalinated by continental runoff. In the western part, salinity on the surface is 28-31‰, and in the eastern part - 31-32‰ and more (up to 33‰ near the Kuril ridge),
In the northwestern part of the sea, due to desalination, the salinity on the surface is 25‰ or less, and the thickness of the desalinated layer is about 30-40 m.
Salinity increases with depth in the Sea of Okhotsk. At horizons of 300-400 m in the western part of the sea, salinity is 33.5‰, and in the eastern part it is about 33.8‰. At a horizon of 100 m, salinity is 34‰ and then towards the bottom it increases slightly, by only 0.5-0.6‰.
In individual bays and straits, the salinity value and its stratification may differ significantly from the waters of the open sea, depending on local conditions.
In accordance with temperature and salinity, denser waters are observed in winter in the northern and central areas of the sea, covered with ice. The density is somewhat lower in the relatively warm Kuril region. In summer, the density of water decreases, its lowest values are confined to zones of influence of coastal runoff, and the highest are observed in areas of distribution of Pacific waters. In winter, it rises slightly from the surface to the bottom. In summer, its distribution depends on temperature in the upper layers, and on salinity in the middle and lower layers. In summer, a noticeable density stratification of waters is created vertically, the density increases especially noticeably at horizons of 25-50 m, which is associated with the heating of waters in open areas and desalination off the coast.
Wind mixing occurs during the ice-free season. It occurs most intensely in spring and autumn, when strong winds blow over the sea, and the stratification of waters is not yet very pronounced. At this time, wind mixing extends to horizons of 20-25 m from the surface.
Intense ice formation over most of the sea stimulates enhanced thermohaline winter vertical circulation. At depths of up to 250-300 m, it spreads to the bottom, and below it is prevented by the maximum stability that exists here. In areas with rugged bottom topography, the spread of density mixing into the lower horizons is facilitated by the sliding of water along the slopes.
Ice cover
Severe and long winters with strong northwest winds contribute to the development of large masses of ice in the sea. The ice of the Sea of Okhotsk is an exclusively local formation. Here there are both fixed ice - fast ice, and floating ice, which is the main form of sea ice.
Ice is found in varying amounts in all areas of the sea, but in summer the entire sea is cleared of ice. The exception is the area of the Shantar Islands, where ice can persist in the summer.
Ice formation begins in November in the bays and lips of the northern part of the sea, in the coastal part of the island. Sakhalin and Kamchatka. Then ice appears in the open part of the sea. In January and February, ice covers the entire northern and middle part of the sea.
In normal years, the southern border of the relatively stable ice cover bends to the north and runs from the La Perouse Strait to Cape Lopatka.
The extreme southern part of the sea never freezes. However, thanks to the winds, significant masses of ice are carried into it from the north, often accumulating near the Kuril Islands.
From April to June, destruction and gradual disappearance of the ice cover occurs. On average, sea ice disappears in late May - early June. The northwestern part of the sea, due to currents and the configuration of the shores, is most clogged with ice, which persists until July. Ice cover in the Sea of Okhotsk lasts for 6-7 months. More than 3/4 of the sea surface is covered with floating ice. The compact ice of the northern part of the sea poses serious obstacles to navigation even for icebreakers.
The total duration of the ice period in the northern part of the sea reaches 280 days a year.
The southern coast of Kamchatka and the Kuril Islands belong to areas with little ice cover: here the ice lasts on average no more than three months a year. The thickness of the ice that grows during the winter reaches 0.8-1 m.
Strong storms and tidal currents break up the ice cover in many areas of the sea, forming hummocks and large open waters. In the open part of the sea, continuous, motionless ice is never observed; usually the ice here is drifting, in the form of vast fields with numerous leads.
Some of the ice from the Sea of Okhotsk is carried into the ocean, where it almost immediately collapses and melts. In severe winters, floating ice is pressed against the Kuril Islands by northwestern winds and clogs some straits.
Economic importance
There are about 300 species of fish in the Sea of Okhotsk. Of these, about 40 species are commercial. The main commercial fish are pollock, herring, cod, navaga, flounder, sea bass, and capelin. Salmon catches (chum salmon, pink salmon, sockeye salmon, coho salmon, chinook salmon) are small.
The extreme points characterizing the geographical position of the Sea of Okhotsk are the following: the top of the Penzhina Bay (62° 42" N, 164° 25" E, in the north; the Nemuro (Izmena) Strait (43° 43" N, 145 ° 15"E in the south; the top of the "Udskaya Bay (54°50"N, 135°10"E in the west and the mouth of the Penzhina River (62°30"N 164°45" in d.) to the east.
The Sea of Okhotsk is surrounded on almost all sides by mountain structures. In the east, west and south are the Cenozoic folded ridges of Kamchatka, Sakhalin and Hokkaido. In the northwest, the East Transbaikal-Amur region of Mesozoic folding approaches the Sea of Okhotsk. Mountain structures either come close to the shore or are separated from the Sea of Okhotsk by vast lowlands (as in Kamchatka, the northern part of Sakhalin and near the mouth of the Amur and other rivers). The absolute height of mountain ranges is on average 1–2.5 km, increasing in Kamchatka to 3.5 km.
The largest water supply from the Amur is 371 km3. The rivers of the northwestern coast (Tugur, Uda, Ulya, etc.) bring approximately 57.2 km3 of water; rivers of the northern coast (Okhota, Kukhtui, Ulbeya, Inya, Taui, Yama, Gizhiga, Penzhina, etc.) - approximately 82.1 km3; Kamchatka rivers - 52.3 km3; rivers of the Kuril Islands and Hokkaido - 6.8 km3; Sakhalin River - 16.6 km3, etc.
Geological history of the Sea of Okhotsk
The northern shallow waters and the central part of the Sea of Okhotsk represent a relatively stable platform, not “captured by tertiary folding and experiencing recent subsidence. The Deryugin Basin and the TINRO depression also formed relatively recently. They can be considered as marginal depressions in relation to the folded structures of Sakhalin and Kamchatka.
The southern deep-sea basin is the most ancient depression in the Sea of Okhotsk. Its development continues to this day. The Kuril Arc is a large double geoanticline, the inner ridge of which is crowned by a chain of active volcanoes associated with a large deep fault; the outer ridge appears to be of more ancient origin; There are no manifestations of modern volcanic activity on it.
The southern deep-sea basin, together with the Kuril island arc and the adjacent Kuril-Kamchatka trench, is part of the zone of incomplete Cenozoic folding, i.e. they are part of the modern geosynclinal system. The most intense volcanic and seismic activity is concentrated here.
Volcanic activity is especially pronounced in the Kuril Islands area, where there are 39 active land volcanoes and a large number of underwater volcanoes. There are five active volcanoes on the island of Hokkaido. The most powerful earthquakes are also concentrated in the Kuril Islands area; they reach 9 points here. Weaker earthquakes were recorded on Sakhalin (up to 7-8 points) and on the northern coast of the Sea of Okhotsk (up to 5-7 points). Minimal seismicity is observed in the northwestern part of the Sea of Okhotsk.
Bottom sediments
In the coastal areas of the Sea of Okhotsk, the bottom is covered with boulder-pebble-gravel and sandy sediments. Boulder-pebble-gravel sediments (fragment sizes range from 10 cm to 1 mm) are common in certain areas of the bottom at depths of several meters; Pebble-gravel sediments occupy vast areas not only near the coast, but also in the open sea. They are also found on the tops and slopes of underwater rises. Most often, such sediments are found at depths of up to 50-100 m, and in some places - at depths of up to 1200-2500 m.
In the zone of distribution of pebble-gravel sediments, small patches of shell or bryozoan deposits are found. Sands (particle sizes 1-0.1 mm) cover large areas on continental and island shallows. They are common along the coasts and seaward of the zone of pebble-gravel sediments, most often at depths of 30-300 m.
In areas adjacent to the Kuril Islands, they are found at depths of up to 1500-2500 m. Foraminiferal sands are found here in some places. In the deeper parts of the Sea of Okhotsk, silty, silty-clayey and clayey silts are common.
Silty silts (particle sizes 0.1–0.01 mm) are deposited on the outer edge of shelves and on slopes, as well as on underwater elevations in the central part of the Sea of Okhotsk at depths of up to 1000 m. In the area of the Kuril Islands they extend to depths of up to 2800– 3000 m. Silty-clayey silts (containing 50-70% of particles less than 0.01 mm) extend to the maximum depths of the Sea of Okhotsk. They usually contain from 20 to 50% (or more) amorphous silica, mainly in the form of skeletons of diatoms, so that these sediments can be classified as siliceous diatomaceous oozes. Bottom sediments in the area of the Kuril Islands, as a rule, include pyroclastic material and in many places change into tuffite deposits of granulometric types.
The study of the remains of diatoms, as well as spores and pollen in sediment cores up to 34 m long, made it possible to identify three warm-water horizons in the Sea of Okhotsk, corresponding to the post-glacial (Holocene) and the last two interglacial epochs. Between them two horizons are identified, synchronous with two eras of Quaternary glaciation.
Climate of the Sea of Okhotsk
Due to the fact that a significant part of it extends deeply into the Asian continent with very cold and long winters, the climate of the Sea of Okhotsk, especially in winter, in the northern part of the sea differs little from the climate of the polar seas. From October to April, the winter monsoon sets in in the Sea of Okhotsk with fresh winds predominantly from the north or north-west (75%), often of storm force. Summer monsoons, interspersed with calms (30%), begin in May and continue until September. Average annual air temperatures in the northern part of the Sea of Okhotsk are from -6 to -6.9 ° C, and in the southern part about +5 ° C. In January, the minimum temperature in the city of Okhotsk is -25.2 ° C, and the maximum (Cape Soya. In summer, the maximum and minimum average temperatures are approximately 18 and 11 ° C. The average annual precipitation in the north is 230-300 mm, in the south 800-1000 mm, which is explained by the influence of dry continental air in the northwest and humid sea air in the south .For 6-7 months, 3/4 of the Sea of Okhotsk water area is covered with ice.Unrest in the Sea of Okhotsk can reach great strength, especially during autumn-winter storms and during the passage of typhoons. At such times, the height of waves in the open sea can reach 8-10 m or more, and the length can reach 100-130 m. Amount of water entering the Sea of Okhotsk from Japan, approximately 15 thousand km3; continental runoff water is 600 km3; atmospheric precipitation is approximately 900 km3 per year.
A narrow strip of counterclockwise coastal currents extends along the coastline. In the southeastern part of the Sea of Okhotsk, it begins in the area of the northernmost Kuril Straits, through which the surface waters of the Pacific Ocean enter the Sea of Okhotsk. These waters then spread along the coast of Kamchatka to the north.
The rather strong Soya Current, caused by the influx of water from the Sea of Japan through the La Perouse Strait, is part of the coastal circulation to the southwest. Coastal current velocities range from 11–20 cm/s off the coast of Kamchatka to 50–90 cm/s in the Soya Current area.
A feature of the abyssal circulation of the Sea of Okhotsk is a warm (about 2.5° C) deep current entering the Sea of Okhotsk from the Pacific Ocean through a gap in the underwater rise of the Kuril tectonic arc near the Kruzenshtern Strait at a depth of 750-1250 m. In the Sea of Okhotsk it branches: one a branch goes north, the other goes south, to Sakhalin, along the inner slope of the Kuril Islands.
The upper layers of the water column are highly saturated with oxygen (up to 103%). The oxygen minimum (up to 1 ml 02 / l) is confined to the warmest deep waters (750-1500 m); in the Deryugin Basin it is located near the bottom. In the southern deep-sea basin, the oxygen saturation of bottom waters increases. The waters of the Sea of Okhotsk are rich in nutrients, the concentration of which increases with depth. The maximum content of silicon and phosphorus at a depth of 4000 m, respectively, is 90 mg/l.
Chemical composition of water in the Sea of Okhotsk favors the development of phytoplankton, the main components of which are peridinea (58 species) and diatoms (290 species), the latter accounting for 70-100% of the phytoplankton biomass. Phytoplankton biomass can reach 20 g per 1 m3 of water.
The coastal flora of the Sea of Okhotsk includes about 300 species of algae, among which kelp predominates. The ichthyofauna of the Sea of Okhotsk includes about 300 species and subspecies of fish, 30 of which are of commercial importance
