The area of the Sea of Okhotsk is 1.603 million square meters. km. Average depth 1780 m maximum depth 3521 m. West Side The sea has shallow depth and is located on the continental shelf. In the center of the sea are the Deryugin depression (in the south) and the TINRO depression. In the eastern part there is the Kuril Basin, where the depth is maximum.
From October to May-June, the northern part of the sea is covered with ice. The southeastern part practically does not freeze.
The coast in the north is heavily indented; in the northeast of the Sea of Okhotsk its largest bay is located - Shelikhov Bay. Of the smaller bays in the northern part, the most famous are the Eirine Bay and the bays of Sheltinga, Zabiyaka, Babushkina, Kekurny, Odessa Bay on the island of Iturup. In the east, the coastline of the Kamchatka Peninsula is practically devoid of bays. In the southwest, the largest are Aniva and Terpeniya bays.
Fishing (salmon, herring, pollock, capelin, navaga, etc.).
Main ports: on the mainland - Magadan, Ayan, Okhotsk (port point); on the island of Sakhalin - Korsakov, on the Kuril Islands - Severo-Kurilsk.
The Sea of Okhotsk is named after the Okhot River, which in turn comes from the Even word okat - “river”. The Japanese traditionally called this sea "Hokkai" (北海), literally "North Sea". But since now this name refers to North Sea Atlantic Ocean, then they changed the name of the Sea of Okhotsk to “Ohotsuku-kai” (オホーツク海), which is an adaptation of the Russian name to the norms of Japanese phonetics.
The sea is located on the Okhotsk subplate, which is part Eurasian plate. Bark under for the most part Sea of Okhotsk continental type.
The Sea of Okhotsk is one of the largest and deepest seas in Russia. Important sea routes linking Vladivostok with the northern regions pass here. Far East and the Kuril Islands. Major ports on the coast of the mainland - Magadan and Okhotsk; on the island of Sakhalin - Korsakov; on the Kuril Islands - Severo-Kurilsk.
The Sea of Okhotsk was discovered by Russian explorers I. Yu. Moskvitin and V. D. Poyarkov in the first half of the 17th century. In 1733, work began on the Second Kamchatka Expedition, whose participants compiled detailed maps of almost all of its shores.
The Sea of Okhotsk, also called the Lama or Kamchatka Sea, is a semi-enclosed sea in the northwestern part of the Pacific Ocean. It washes the shores of Russia and Japan (Hokkaido Island).
From the west it is limited by the continent of Asia from Cape Lazarev to the mouth of the Penzhina River; from the north - the Kamchatka Peninsula; from the east by the islands of the Kuril ridge and from the south by the islands of Hokkaido and Sakhalin.
The Sea of Okhotsk is connected to the Pacific Ocean through the Kuril Straits system. There are more than 30 such straits and their total width is more than 500 kilometers. It communicates with the Sea of Japan through the Nevelskoy and La Perouse straits.
Characteristics of the Sea of Okhotsk
The sea is named after the Okhota River flowing into it. The area of the Sea of Okhotsk is 1,603,000 square kilometers. Its average depth is 1780 meters, with maximum depth at 3916 meters. From north to south the sea stretches for 2445 kilometers, and from east to west for 1407 kilometers. The approximate volume of water contained in it is 1365 thousand cubic kilometers.
The coastline of the Sea of Okhotsk is slightly indented. Its length is 10,460 kilometers. Its largest bays are considered to be: Shelikhov Bay, Sakhalin Bay, Udskaya Bay, Tauiskaya Bay and Academy Bay. The northern, northwestern and northeastern shores are high and rocky. At the confluence of large rivers (Amur, Uda, Okhota, Gizhiga, Penzhina), as well as in the west of Kamchatka, in the northern part of Sakhalin and Hokkaido, the banks are predominantly low-lying.
From October to May - June, the northern part of the sea is covered with ice. The southeastern part practically does not freeze. In winter, the water temperature at the sea surface ranges from −1.8 °C to 2.0 °C; in summer, the temperature rises to 10-18 °C.
Salinity surface waters The Sea of Okhotsk is 32.8-33.8 ppm, and the salinity of coastal waters usually does not exceed 30 ppm.
Climate of the Sea of Okhotsk
The Sea of Okhotsk is located in the monsoon climate zone of temperate latitudes. For most of the year, cold, dry winds blow from the mainland, cooling the northern half of the sea. From October to April, negative air temperatures and stable ice cover are observed here.
In the northeastern part of the sea average temperature in January - February it ranges from - 14 to - 20 ° C. In the northern and western regions, the temperature varies from - 20 to - 24 ° C. In the southern and eastern parts of the sea, winter is much warmer from - 5 to - 7 ° C.
Average temperatures in July and August, respectively, are 10-12 ° C; 11-14° C; 11-18° C. The annual amount of precipitation in different places of the Sea of Okhotsk is also different. Thus, in the north, 300-500 mm of precipitation falls per year; in the west up to 600-800 mm; in the southern and southeastern parts of the sea - over 1000 mm.
In terms of the composition of organisms living in the Sea of Okhotsk, it is more arctic in nature. Species of the temperate zone, due to the thermal effects of oceanic waters, are inhabited mainly in the southern and southeastern parts of the sea.
In coastal zones there are numerous settlements of mussels, littorinas and other mollusks, barnacles, sea urchins, among crustaceans there are many crabs.
A rich invertebrate fauna has been discovered at the great depths of the Sea of Okhotsk. Glass sponges, sea cucumbers, deep-sea corals, and decapod crustaceans live here.
The Sea of Okhotsk is rich in fish. The most valuable salmon species are: chum salmon, pink salmon, coho salmon, chinook salmon and sockeye salmon. Commercial fishing for herring, pollock, flounder, cod, navaga, capelin and smelt is carried out here.
The Sea of Okhotsk is home to large mammals - whales, seals, sea lions and seals. There are many seabirds that organize noisy “bazaars” on the coasts.
The UN recognized the enclave of the Sea of Okhotsk as part of the Russian shelf
Inessa Dotsenko
The UN Commission on the Limits of the Continental Shelf recognized the Sea of Okhotsk enclave with an area of 52 thousand square kilometers as part of the Russian continental shelf.
According to ITAR-TASS, this was stated by the Minister natural resources and ecology of the Russian Federation Sergei Donskoy.
We have officially received a document from the UN Commission on the Continental Shelf on the satisfaction of our application to recognize the enclave in the Sea of Okhotsk as the Russian shelf. This has actually already taken place, so I would like to congratulate everyone on this,” he said.
The commission's decision, according to the minister, is unconditional and reverse action does not have. Now the enclave is fully subject to Russian jurisdiction.
As ITAR-TASS reports, Donskoy also said that Russia’s application to expand the continental shelf in the Arctic will be ready this fall. The time for submitting the application to the UN Commission on the Limits of the Continental Shelf depends on how other countries’ claims to the enclave in the Arctic will be built.
All resources that will be discovered there will be extracted exclusively within the framework of Russian legislation,” Donskoy noted. He said that according to geologists, the total volume of hydrocarbons discovered in this area exceeds a billion tons.
Magadan Governor Vladimir Pecheny believes that recognition of the enclave in the middle of the Sea of Okhotsk as part of the Russian continental shelf opens up new prospects for the economy of Kolyma and the entire Far East. First of all, it will relieve the region’s fishermen of numerous administrative barriers.
Firstly, fishing for fish, crab, and shellfish can be carried out freely anywhere in the Sea of Okhotsk. No special permits from the border service will be required either when going to sea or upon returning. Secondly, when Russian territory there will be not only a 200-mile zone, but the entire sea, we will get rid of poaching by foreign fishermen in our waters. It will be easier to preserve the unique environment,” the press service of the regional government quotes Pecheny as saying.
Reference
In the center of the Sea of Okhotsk there is an elongated enclave of considerable size. Previously, all of it was considered the “open sea”. Vessels of any state could move and fish freely on its territory. In November 2013, Russia managed to prove rights to 52 thousand square kilometers of water in the center of the Sea of Okhotsk. For comparison, this is larger than the area of Holland, Switzerland or Belgium. The center of the Sea of Okhotsk ceased to be part of the World Ocean and became completely Russian. After approval at the UN session, the process of legally classifying the enclave as part of the Russian continental shelf can be considered completely completed.
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 conditional lines 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 marginal seas 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 the belt 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 often form. 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. At long distance The coastline 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 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, Ricord 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 mainly surrounded by high and steep banks. 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. It's huge flat plain, lying at a depth of about 3300 m. Its width in the western part is approximately 212 km, 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 northern tip O. 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 are well expressed different kinds periodic tidal currents: 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 have a very complex nature. 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 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 highest altitudes waves reach 10-11 m. The most turbulent are the southern and southeastern regions of the sea, where the average frequency of storm waves is 35-40%, and in the northwestern part it decreases to 25-30%. At strong excitement 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 northwest of the sea is –20 - 25°, in central regions–10–15°, and in the southeastern 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 above southern part Tropical cyclones - typhoons - pass through the seas quite often. 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 position, large length along the meridian, monsoon changes in winds 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:
superficial water mass, which 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. Most high values temperatures and salinities are observed in the northeast and partly in northwestern regions, which is associated here with the rise of waters, and the smallest values of the characteristics are characteristic of the western and southern regions, where the 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 Kruzenshtern 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 south and southeastern parts sea, along the Kuril Islands, 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, the 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. Some less density 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 time 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 there is never a continuous stationary ice, 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 harsh winters The floating ice is pressed against the Kuril Islands by north-west 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.
Sea of Okhotsk- one of the largest water basins washing the shores of our country.
Its area - 1,603,000 km 2 - is one and a half times larger than the area of the Sea of Japan and is second only to the Bering Sea, from which it is separated by the Kamchatka Peninsula. The Sea of Okhotsk is fenced off from the Pacific Ocean by a chain of active and extinct volcanoes of the Kuril island chain, and the islands of Hokkaido and Sakhalin are fenced off from the Sea of Japan. Penzhinskaya Bay in the north, Udskaya in the west, Tugursky, Academy, Terpeniya and Aniva bays in the south protrude deep into the land. Completely closed in the north, the Sea of Okhotsk in the west exchanges waters through 19 Kuril straits with the Pacific Ocean, and even further south, through the La Perouse and Tatar straits, with the Sea of Japan. Its coastline stretches for 10,444 km.
Morse covers the ancient land of Okhotia, and therefore it is shallow over most of its water area. Only in the South Okhotsk Basin the depth reaches 3372 m. If you look at the geomorphological map of the Sea of Okhotsk, you can find a number of depressions and uplifts on it: the heights of the USSR Academy of Sciences, the TINRO, Deryugin depressions, the Makarov and Peter Schmidt troughs. In the north, the shelf of the Sea of Okhotsk is shallow; to the south, the depths gradually increase. The shelf area makes up 36% of the entire sea area.
The Sea of Okhotsk feeds many large and small rivers, but its main artery is the Amur, the great river of East Asia. The shores of the Sea of Okhotsk islands and the Kamchatka Peninsula are mostly low-lying, swampy, with relict salt lakes, bays and lagoons. There are especially many of them on Sakhalin. The western coast of the Sea of Okhotsk is mountainous, with steep straight shores. The Pribrezhny and Ulinsky ridges and the spurs of the Suntar-Khayata ridge come close to the sea near Ayan, Okhotsk and Magadan.
In the Sea of Okhotsk, almost all the islands are located near the coast. The largest of them is Sakhalin, whose area is 76,400 km 2. The Kuril archipelago, stretching for 1200 km between the Japanese island of Hokkaido and Cape Lopatka in Kamchatka, has 56 islands (except for small ones of volcanic origin). Volcanologists identified and recorded here. 38 active and 70 extinct volcanoes. In the extreme west of the sea are the Shantar Islands. The most significant of them is Big Shantar. Its area is 1790 km2. Some of these 15 islands have long been inhabited by birds and have attracted the attention of scientists. South of the Terpeniya Peninsula is the small island of Tyuleniy, famous for its seal rookery. But the tiny island of Iona, lying 170 miles east of Ayan, is just a lonely rock, visited only by seabirds and sea lions. In addition to these fragments of land, at the very top of the Sakhalin Bay there are the islands of Chkalov, Baidukov and Belyakov, named after the brave Soviet aces.
The water masses of the Sea of Okhotsk, moving mainly counterclockwise, form a cyclonic system of currents. This is due to two main factors - river water flow and influx warm waters Pacific Ocean through the Krusenstern and Bussol straits. Around the Shantar Islands there is a circular movement in reverse direction(clockwise), reminiscent of the currents in the bays of Aniz and Terpeniya.
Branches of two powerful water streams enter the south of the sea - the warm Kuro-Sivo current and the cold Oya-Sivo current. In addition to these currents, jets of the warm Soya Current penetrate into the Sea of Okhotsk through the La Perouse Strait. Influence warm currents intensifies in summer and weakens in winter. In addition to the Oya-Sivo Current, which flows into the Sea of Okhotsk through the Kuril Straits, the water cooling is also caused by the along-shore East Sakhalin Current, directed from north to south. Through the southern Kuril Straits, cold waters flow into the Pacific Ocean.
The Sea of Okhotsk is known for its powerful tides. In Penzhinskaya Bay their height reaches almost 13 m (a kind of record for the USSR), a slightly smaller difference in sea levels at full (high tide) and low (low tide) water is observed in Gizhiginskaya Bay and on the Shantar Islands.
Storms often occur in the vast expanses of the Sea of Okhotsk. The southern region of the sea is especially troubled, where strong winds blow from November to March, and wave crests rise to a height of 10-11 m. Another feature of this huge water basin- his efficiency is the greatest in the Far East. Only off the western shores of Kamchatka and the Middle Kuril Islands is a strip of clean water preserved in winter. The destruction of the ice cover lasts from April to August - as we see, it is not by chance that our sea is called icy. The movement of air masses also affects the harsh nature of the Sea of Okhotsk. The winter anticyclone determines the northwestern direction of the winds, and in the summer southeastern winds predominate, which is typical for the monsoon climate. The amplitude of annual air temperature fluctuations is 35° C, 10° higher than that in the Bering and Japan seas. The average annual air temperature in the Sea of Okhotsk varies from -7° (in the Gizhigi region) to 5.5° (Abashiri in Hokkaido).
Summer heating of the waters of the Sea of Okhotsk is limited to the uppermost layers. In August, the surface water temperature reaches 16-18° off the coast of Hokkaido and 12-14° C in the northwest. The lowest summer surface water temperatures are found along the Middle Kuril Islands (6-8°C) and near the Pyagina Peninsula (4-6°C). In February (the coldest month), negative temperatures prevail throughout the Sea of Okhotsk. Hydrologists call the layer of “permafrost” the horizon of water lying at a depth of between 50 and 100 m. Off the coast of Sakhalin, the temperature of this layer of water is the lowest and reaches -1.6°. Deeper, about 200 m, the temperature again rises by 1.5-2° above zero. Only in the northern part of the sea and southeast of Sakhalin is this depth characterized by negative temperatures. With further diving, the temperature slowly increases, reaching 2.4° at around 1000 m (due to warmer ocean waters), and then decreases slightly again. At depths of two to three thousand meters it is 1.9° C in winter and summer.
In the area of the Kuril Islands, the salinity of the waters of the Sea of Okhotsk reaches 33 ppm (a little more than 30 grams of salts in one liter). In other places the salinity is lower; The most desalinated water is in the Sakhalin Bay, where the Amur flows. The salinity of sea water increases with depth, and below two thousand meters it is quite consistent with ocean water, reaching 34.5 ppm.
Maximum saturation of water with oxygen and highest degree hydrogen ion concentrations were recorded at a depth of 10 m, which is associated with the intensive development of phytoplankton. At a depth of 1000-1500 m, a sharp oxygen deficiency was noted - up to 10% saturation. Here a zone of “biological depression” is formed. Deeper the oxygen content increases to 20-25%. Filled through straits with oceanic waters with a low oxygen content, the Sea of Okhotsk basin contains water masses that are weakly mixed due to sharp differences in density between individual layers. Vertical circulation of water occurs within the first two-hundred-meter layer. This is caused by the formation of a denser and colder intermediate layer of water at a depth of 50-100 m. Their winter cooling is accompanied by an increase in salinity and density, which leads to the sinking of these masses from the surface.
Differences in water salinity in the Amur Estuary can reach 22 ppm. Salty water comes into the estuary from the north sea waters, mixing with fresh river water. With strong southern winds, a countercurrent sometimes occurs in the Amur, salty water rises up its bed, and a so-called “faunal barrier” is formed, which animals cannot overcome.
Bottom sediments of the Sea of Okhotsk are represented by sands, pebbles and rocky placers with an admixture of silt on the shelf. In closed bays, separated from the sea by sand spits, pure silts are deposited. Sandy sediments predominate in the Sakhalin Bay, and pebble sediments predominate in the Penzhinskaya Bay. In the deep-sea basin in the south of the sea, the bottom is covered with sandy silts, and in its central part, greenish and brown silts at depths between 1000 and 3000 m determine the distribution of the zone of stagnant waters. Iron-manganese nodules were discovered around the island of Iona at a depth of about 500 m.
There are many tiny flint shells in the sediments single-celled organisms- Diamotaceous algae and radiolarians.
The history of the Sea of Okhotsk goes back many hundreds of millions of years. Seaweed and bacteria that existed over one and a half billion years ago left traces of their vital activity on west coast the present Sea of Okhotsk. In the Silurian period (about 450 million years ago), the southwestern part of the modern Sea of Okhotsk basin and the area of Sakhalin Island were under water. The same situation persisted in the Devonian (400-350 million years ago) in the area of the Shantar Islands, where even coral reefs, or rather reef-like communities with the participation of coral polyps, bryozoans, sea urchins and crinoids, developed. However, most of the basin rose above sea level during the Paleozoic. The ancient land of Okhotia located here about 220 million years ago included the central part of the present sea, Sakhalin and Kamchatka. From the north, west and south, Okhotia was washed by a fairly deep sea with many islands. Findings of remains of ferns and cycadophytes indicate that subtropical flora grew here, which required heat and humid climate.
Another 100 million years passed. In place of Sakhalin and the Japanese Islands there is a huge chain of coral reefs, larger in size than the current Great Barrier Reef off the eastern coast of Australia. The Jurassic reef system probably marked for the first time the position of the future island arc that separated the Sea of Japan from the Pacific Ocean. A major transgression flooded the entire Okhotia and adjacent land areas about 80 million years ago. On the site of Kamchatka, two parallel island ridges arose. As we get closer to modern era they extended more and more in a southern direction, separating the basins of the Bering and Okhotsk seas with another arc.
50-60 million years ago, a sharp drop in sea level led to the complete drying of Okhotia and Beringia. Great connoisseur ancient history Sea of Okhotsk professor G.W. Lindberg convincingly showed that Okhotia was even mountainous in places and large rivers flowed through its territory, starting far in the west - Paleoamur and Paleopenzhina. They developed deep canyons, which later became underwater depressions. Some forms of land relief and traces of ancient coastlines have been preserved on the bottom of the Sea of Okhotsk to this day.
Okhotia went under water about 10 thousand years ago, with the end of the last Quaternary glaciation. Over time, the South Okhotsk Basin was separated from the Pacific Ocean by the youngest island arc of the Far East - the Kuril Islands - and the outlines of the Sea of Okhotsk were finally determined.
Centuries have passed. The first inhabitants appeared on the Okhotsk coast. The bays and estuaries of the sea were replete with seal rookeries, and walruses entered the northern part of it. The ancient northerners were engaged in sea fishing, collecting edible shellfish and algae.
The significant similarity of the ancient cultures of the Koryaks, Aleuts and the indigenous inhabitants of Kodiak Island near Alaska, noted by the Siberian historian R.V. Vasilievsky, gives reason to assume that aborigines took part in the settlement of the New World, at least starting from the Neolithic, and perhaps earlier Sea of Okhotsk and Kamchatka. This researcher discovered proto-Aleut features in the structure of Koryak harpoons, the shape of stone fat lamps and arrowheads, characteristic type tools with notched grooves, hooks, spears, awls, spoons and other hunting and household equipment.
In the south of the Sea of Okhotsk there was an island culture, similar in a number of features to the ancient Koryak. We note the presence of a rotating harpoon and a significant number of seal and whale bones at the excavations, similar ceramics and stone implements of the Amur settlements and sites of the ancient inhabitants of Sakhalin and the Kuril Islands.
Soviet anthropologist M. G. Levin noted that “the anthropological, linguistic and cultural closeness of the Nivkhs of Sakhalin and Amur, undoubtedly reflecting the processes constant communication between them over a number of recent centuries, goes back, at the same time, with its roots in the more distant past - the Neolithic era... It is likely that the Ainu legends about tons depict the ancestors of the Gilyaks or related tribes, whom the Ainu found on Sakhalin during their resettlement to this island" (Ethnic anthropology and problems of enthogenesis of the peoples of the Far East, M., 1958, pp. 128 - 129).
But who are the Nivkhs, or Gilyaks, as these indigenous inhabitants of the Lower Amur and Sakhalin were called until recently? The word "nivkh" means "man". Rituals and customs, religious beliefs, myths and legends of the Nivkhs reflect the history of this ancient people of the Amur region and have long been the subject of scientific research. Not long ago, scientists were excited by reports of striking analogies in the language of the Nivkhs and some African tribes, in particular in Western Sudan. It also turned out that the dugout boats and axes of the Nivkhs are similar to the boats and axes of the inhabitants of the islands of Tahiti and the Admiralty.
What do such coincidences indicate? It is still difficult to answer this question. Maybe some thread will stretch from the sacred chants of the Nivkhs?
The sea was still boiling. The seals and fish died.
There are no people, no fish.
Then a mountain was born from the sea.
Then the earth was born from the sea.
Doesn't this legend indicate that the Kuril Islands were born before the eyes of the Nivkhs? If we admit the possibility of such an interpretation, then we should recognize the Nivkhs as one of the most ancient peoples of the Far East. From shamanic chants we learn about warm seas and white mountains, shallows of white sand and abandoned wives of the Nivkhs. As it appears, we're talking about O coral islands The Pacific Ocean, from where the ancestors of the Nivkhs could have come to the Sea of Okhotsk basin.
The history of the Ainu, who unexpectedly appeared among the aborigines of Sakhalin, seems even more mysterious. As early as 1565, the monk de Froes reported in “ Japanese letters": "... the Ainu, with their almost European appearance and thick hair covering their heads... differed sharply from the beardless Mongoloids." Their belligerence, endurance, the custom of women to blacken their lips, nudity, barely covered by the “belt of modesty” so common among the South Pacific Islanders - all this so amazed the imagination of travelers that some of them even called the Ainu black people. Vasily Poyarkov’s “questioning speeches” talk about the island lying to the east (i.e. Sakhalin), the Nivkhs inhabiting its northern part, and “black people called Kuys” living in the south. Local historians discovered a Negroain site in Petropavlovsk-Kamchatsky already in our days.
According to the outstanding Soviet scientist L. Ya. Sternberg, the cultural and anthropological features of the Ainu bring them closer to some peoples of South India, Oceania and even Australia. One of the arguments in favor of the theory of the Austronesian origin of the Ainu is the cult of the snake, which is also common among some tribes of Southeast Asia.
When in the 2nd millennium BC. e. The Ainu came to the southern islands of the Sea of Okhotsk, they found Tonchen here. If you believe the legends, these were sea hunters and fishermen.
The conclusion suggests itself that the peoples who once inhabited the southern archipelagos of the Pacific Ocean, India and even Australia rolled into the area of the Sea of Okhotsk in waves. Partially mixing with the local population, they adopted its culture and customs. Typical inhabitants of southern countries, the Ainu borrowed the design of a canoe from the Itelmen of Kamchatka, a type of boat from the Tonchi of Sakhalin, and winter clothing from the Nivkhs. Even in Ainu ornaments, as R. V. Kozyreva writes (Ancient Sakhalin, Leningrad, 1967), simple and geometric patterns and notches characteristic of early periods history of local culture.
Already before human eyes, the formation of the modern coastline of the Sea of Okhotsk continued. Even in new and modern times its level did not remain constant. Just 200 years ago, as Khabarovsk paleogeographer L.I. Sverlova believes, Sakhalin was connected to the mouth of the Amur. According to her calculations based on establishing functional dependence Between fluctuations in the level of the World Ocean and changes in the temperature regime of the Earth, the lowest sea waters occurred in 1710-1730. Comparing these data with the dates of the voyages of famous sailors, L. I. Sverlova came to the conclusion that J. F. Laieruz in 1787, W. R. Broughton in 1797, and even I. F. Krusenstern in 1805 did not could pass through the Tatar Strait, because it did not exist at all: Sakhalin in those years was a peninsula.
In 1849-1855, during the period of the Amur expedition, sea waters had already blocked the bridge between the mainland and Sakhalin, and this allowed G.I. Nevelsky to convey to N.N. Muravyov: “Sakhalin is an island, entrance to the estuary and the Amur River is possible for seagoing vessels from the north and south. The age-old delusion has been positively dispelled, the truth has been revealed” (B.V. Struve. Memoirs of Siberia 1848-1854, St. Petersburg, 1889, p. 79).
And yet L.I. Sverlova apparently overestimates the real significance of ocean level fluctuations. Without a shadow of a doubt, she writes, for example, that in 1849-1855. this level was 10 m higher than the modern one. But where, in this case, are the marine sediments, terraces, abrasion areas and many other signs that inevitably accompany displacements of coastlines? The only proof is more high level Far Eastern seas in post-glacial times - a low terrace 1-3 m high, the remains of which have been found in many places. However, the time of its formation is several thousand years distant from our days.
THE SEA OF OKHOTSK is a marginal sea in the northwestern part of the Pacific Ocean.
The Sea of Okhotsk is almost completely limited by continental and island coastlines, located between the shores of Eastern Eurasia, its Kamchatka Peninsula, the Kuril Islands chain, the northern tip of Hokkaido and the eastern part of Sakhalin Island. It is separated from the Sea of Japan in the Tatar Strait along the line Cape Sushchev - Cape Tyk, in the La Perouse Strait along the line Cape Crillon - Cape Soya. The border with the Pacific Ocean runs from Cape Nosyappu (Hokkaido Island) along the ridge of the Kuril Islands to Cape Lopatka (Kamchatka Peninsula). Area 1603 thousand km2, volume 1316 thousand km3, greatest depth 3521 m.
The coastline is slightly indented, the largest bays are: Academies, Aniva, Sakhalinsky, Terpeniya, Tugursky, Ulbansky, Shelikhova (with Gizhiginskaya and Penzhinskaya bays); Tauiskaya, Udskaya lips. The north and northwestern shores are predominantly elevated and rocky, most of them abrasive, in places heavily altered by the sea; in Kamchatka, in the northern parts of Sakhalin and Hokkaido, as well as at the mouths of large rivers - low-lying, largely accumulative. Most of the islands are located near the coast: Zavyalova, Spafareva, Shantarskie, Yamskie, and only the small island of Jonah is located in the open sea.
Relief and geological structure of the bottom.
The bottom topography is very diverse. The shelf occupies about 40% of the bottom area, it is most common in the northern part, where it is of the submerged type, its width varies from 180 km near the Ayano-Okhotsk coast to 370 km in the Magadan region. Up to 50% of the bottom area falls on the continental slope (depths up to 2000 m). To the south part is the deepest (more than 2500 m) area of the sea, occupying St. 8% pl. bottom. In the central part of the Sea of Okhotsk, the rises of the Academy of Sciences and the Institute of Oceanology are distinguished, dividing the sea depression into 3 basins (depressions): TINRO in the northeast (depth up to 990 m), Deryugin in the west (up to 1771 m) and the deepest - Kuril in the south (up to 3521 m).
The foundation of the Sea of Okhotsk basin is heterogeneous; power earth's crust 10-40 km. The uplift in the central part of the sea has continental crust; the rise in the southern part of the sea consists of two raised blocks separated by a trough. The deep-sea Kuril Basin with oceanic crust, according to some researchers, is a captured section of the ocean plate; according to others, it is a back-arc basin. The Deryugin and TINRO basins are underlain by transitional crust. In the Deryugin basin, an increased heat flow and hydrothermal activity have been established compared to the rest of the territory, as a result of which barite structures are formed. The sedimentary cover has highest power in basins (8-12 km) and on the northern and eastern shelves, composed of Cenozoic terrigenous and siliceous-terrigenous deposits (near the Kuril Islands with an admixture of tuffaceous material). The Kuril Islands chain is characterized by intense seismicity and modern volcanism. Earthquakes that regularly occur in the area often produce dangerous tsunami waves, such as the one in 1958.
Climate.
The Sea of Okhotsk is characterized by a monsoon climate of temperate latitudes. The sea is located relatively close to the Siberian Pole of Cold, and the Kamchatka ridges block the path to warm Pacific air masses, so in general it is cold in this area. From October to April, the combined influence of the Asian anticyclone and the Aleutian depression prevails over the sea with strong, stable northwestern and northern winds with speeds of 10-11 m/s, often reaching storm force. The coldest month is January, temperatures range from -5 to -25 °C. From May to September, the sea is under the influence of the Hawaiian anticyclone with weak southeast winds of 6-7 m/s. In general, the Pacific (summer) monsoon is weaker than the Asian (winter) monsoon. Summer temperatures (August) range from 18 °C in the southwest to 10 °C in the northeast. The average annual precipitation ranges from 300-500 mm in the north, to 600-800 mm in the west, in the southern and south-eastern parts of the sea - over 1000 mm.
Hydrological regime.
Large rivers flow into the Sea of Okhotsk: Amur, Bolshaya, Gizhiga, Okhota, Penzhina, Uda. The river flow is about 600 km3/year, about 65% falls on the Amur. Desalination of the surface layer of the sea is noted. water due to the excess of river flow over evaporation. The geographical location of the Sea of Okhotsk, in particular its large length along the meridian, the monsoon wind regime, and water exchange through the straits of the Kuril ridge with the Pacific Ocean determine the characteristics of the hydrological regime. The total width of all the Kuril Straits reaches 500 km, but the depths above the rapids in the straits vary greatly. For water exchange with the Pacific Ocean, the Bussol straits with a depth of over 2300 m and the Kruzenshtern strait - up to 1920 m are of greatest importance. This is followed by the Frieza, Fourth Kurilsky, Ricord and Nadezhda straits, all with depths at the rapids of more than 500 m. The remaining straits have depths of less than 200 m and small cross-sectional areas. In small straits, unidirectional flows into the sea or into the ocean are usually observed. In deep straits, a two-layer circulation predominates: in the near-surface layer in one direction, in the near-bottom layer in the opposite direction. In the Bussol Strait, Pacific waters flow into the sea in the surface layers, and flow into the ocean in the bottom layers. In general, the flow of Sea of Okhotsk waters predominates in the southern straits, while the influx of Pacific waters predominates in the northern straits. The intensity of water exchange through the straits is affected. seasonal and annual variability.
In the Sea of Okhotsk, a subarctic structure of waters with well-defined cold and warm intermediate layers is observed; the Sea of Okhotsk, Pacific and Kuril regional varieties are distinguished. There are 5 large water masses in the Sea of Okhotsk: the surface one is a very thin (15-30 m) upper layer, which easily mixes and, depending on the season, takes on spring, summer or autumn modifications with corresponding characteristic values of temperature and salinity; in winter, as a result of strong cooling of the surface layer, the Sea of Okhotsk water mass is formed, which in spring, summer and autumn exists in the form of a cold transition layer at horizons from 40 to 150 m, the temperature in this layer is from -1.7 to 1 °C, salinity 31 -32.9‰; the intermediate one is formed as a result of the sliding of cold waters along the continental slope, is characterized by a temperature of 1.5 °C, a salinity of 33.7‰ and occupies a layer from 150 to 600 m; the deep Pacific is located in a layer from 600 to 1300 m, consists of Pacific water entering the Sea of Okhotsk in the lower horizons of the deep Kuril Straits, and exists as a warm intermediate layer with a temperature of about 2.3 °C and a salinity of 34.3‰, deep Kuril the southern basin is also formed from Pacific waters, located in a layer from 1300 m to the bottom, water temperature 1.85 °C, salinity 34.7‰.
The distribution of water temperature on the surface of the Sea of Okhotsk strongly depends on the season. In winter, the water cools to about -1.7 °C. In summer, the waters are heated most strongly near the island. Hokkaido up to 19 °C, in the central regions up to 10-11 °C. Salinity on the surface in the eastern part of the Kuril ridge is up to 33‰, in the western regions 28-31‰.
The circulation of surface waters is predominantly cyclonic in nature (counterclockwise), which is explained by the influence of wind conditions over the sea. Average current speeds are 10-20 cm/s, maximum values can be observed in the straits (up to 90 cm/s in the La Perouse Strait). Periodic tidal currents are well expressed, the tides are mainly daily and mixed, ranging in size from 1.0-2.5 m in the southern part of the sea, up to 7 m near the Shantar Islands and 13.2 m in Penzhinskaya Bay (the largest in the seas of Russia). Significant level fluctuations (surges) of up to 2 m are caused on the coasts during the passage of cyclones.
The Sea of Okhotsk is an arctic sea; ice formation begins in November in the bays of the northern part and by February spreads to most of the surface. Only the extreme southern part does not freeze. In April, the melting and destruction of the ice cover begins; in June, the ice completely disappears. Only in the area of the Shantar Islands can sea ice partially remain until autumn.
History of the study.
The sea is open in mid-17th century century by Russian explorers I.Yu. Moskvitin and V.D. Poyarkov. The first coastal maps were compiled during the Second Kamchatka Expedition (1733-1743) (see Kamchatka Expeditions). I.F. Kruzenshtern (1805) conducted an inventory of the eastern coast of Sakhalin. G.I. Nevelskoy (1850-1855) examined the southwestern shores of the Sea of Okhotsk and the mouth of the Amur River and proved the island position of Sakhalin. The first complete report on sea hydrology was compiled by S.O. Makarov (1894). IN Soviet time complex systems were deployed in the Sea of Okhotsk research papers. Systematic research has been carried out for many years by the Pacific Fisheries Research Center (TINRO-Center), the Pacific Oceanological Institute of the Far Eastern Branch of the Russian Academy of Sciences, several large expeditions were carried out by the Oceanology Institute on the ship "Vityaz", as well as by ships of the Hydrometeorological Service (see Federal Service of Russia for Hydrometeorology and Monitoring environment), Oceanographic Institute and other institutions.
Economic use.
In the Sea of Okhotsk there are about 300 species of fish, of which about 40 are commercial species, including cod, pollock, herring, navaga, and sea bass. Salmon species are widespread: pink salmon, chum salmon, sockeye salmon, coho salmon, and chinook salmon. Inhabited by whales, seals, sea lions, and fur seals. Crabs are of great economic importance (1st place in the world in terms of commercial crab reserves). The Sea of Okhotsk is promising in terms of hydrocarbons; proven oil reserves exceed 300 million tons. The largest deposits have been identified on the shelves of the Sakhalin, Magadan and West Kamchatka islands (see the article Okhotsk oil and gas province). Sea routes pass through the Sea of Okhotsk connecting Vladivostok with the northern regions of the Far East and the Kuril Islands. Large ports: Magadan, Okhotsk, Korsakov, Severo-Kurilsk.