]. The western part of the sea is located above a gentle continent and has a shallow depth. In the center of the sea are the Deryugin Basins (in the south) and the TINRO Basin. In the eastern part, there is the Kuril basin, in which 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 \u200b\u200bOkhotsk is its largest bay - Shelikhov Bay. Of the smaller bays in the northern part, the most famous are Eirineyskaya Bay and the bays of Sheltinga, Zabiyaka, Babushkina, Kekurny. In the east, the coastline of the Kamchatka Peninsula is practically devoid of bays. In the west, the coastline is heavily indented, forming the Sakhalin Bay and the Shantar Sea. In the south, the largest are Aniva and Terpeniya bays, Odessa Gulf on Iturup Island. The rivers Amur, Okhota, Kukhtui flow into the river.
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The Sea of \u200b\u200bOkhotsk is named after the Okhota River, which in turn comes from Evensk. okat - "river". Previously it was called Lamsky (from Even lamas - "sea"), as well as the Kamchatka sea. The Japanese traditionally called this sea the Hokkai (北海), literally "North Sea". But since now this name refers to the North Sea of \u200b\u200bthe Atlantic Ocean, they changed the name of the Sea of \u200b\u200bOkhotsk to Okhotsuku-kai (オ ホ ー ツ ク 海), which is an adaptation of the Russian name to the norms of Japanese phonetics.
Legal regime
The water area of \u200b\u200bthe Sea of \u200b\u200bOkhotsk consists of internal waters, a territorial sea and an exclusive economic zone of two coastal states - Russia and Japan. In terms of its international legal status, the Sea of \u200b\u200bOkhotsk is closest to a semi-enclosed sea (Article 122 of the UN Convention on the Law of the Sea), since it is surrounded by two or more states and mainly consists of a territorial sea and an exclusive economic zone of two states, but it is not, since connected to the rest of the world's oceans not by a single narrow passage, but by a series of passages. In the central part of the sea, at a distance of 200 nautical miles from the baselines, there is a stretch in the meridional direction, traditionally called Peanut Hole in the English language literature, which is not part of the exclusive economic zone and is an open sea outside the jurisdiction of Russia; in particular, any country in the world has the right here to fish and carry out other activities permitted by the UN convention on the law of the sea, excluding activities on the shelf. Since this region is an important element for the reproduction of the population of some species of commercial fish, the governments of some countries explicitly prohibit their vessels from fishing in this area of \u200b\u200bthe sea.
On November 13-14, 2013, the Sub-Commission, created within the framework of the UN Commission on the Limits of the Continental Shelf, agreed with the arguments of the Russian delegation as part of the consideration of the RF application for recognition of the bottom of the above-mentioned section open sea continuation of the Russian continental shelf. On March 15, 2014, the 33rd session of the Commission in 2014 adopted a positive decision on the Russian application, which was first filed in 2001 and filed in a new version at the beginning of 2013, and the central part of the Sea of \u200b\u200bOkhotsk outside the exclusive economic zone of the Russian Federation was recognized continental shelf of Russia. Consequently, in the central part, other states are prohibited from harvesting "sedentary" biological resources (for example, crab, molluscs) and mining. Fishing for other biological resources, for example, fish, is not subject to the restrictions of the continental shelf. Consideration of the application on the merits became possible thanks to the position of Japan, which, by an official note dated May 23, 2013, confirmed its consent to the consideration of the essence of the application by the Commission, regardless of the resolution of the issue Kuril Islands.
Temperature regime and salinity
Fifteen ships were captured by ice, with about 700 people on board.
The operation was carried out by the forces of the icebreaker flotilla: the icebreakers Admiral Makarov and Krasin, the icebreaker Magadan and the tanker Victoria worked as auxiliary vessels. The coordination headquarters of the rescue operation was located in Yuzhno-Sakhalinsk, work was carried out under the leadership of the Deputy Minister of Transport of the Russian Federation Viktor Olersky.
Most of the vessels got out on their own, icebreakers rescued four vessels: the trawler Cape Elizabeth, the research vessel Professor Kizevetter (first half of January, Admiral Makarov), the refrigerator Coast of Hope and the Sodruzhestvo floating base.
The second freed ship was Professor Kiesewetter, whose captain, as a result of the investigation, was deprived of his diploma for six months.
In the area of \u200b\u200bJanuary 14, the icebreakers gathered together the remaining ships in distress, after which the icebreakers escorted both ships of the convoy on a hitch.
After the break of the "mustache" of the "Commonwealth", it was decided to first lead the refrigerator through the heavy ice.
The wiring was suspended around January 20 due to weather conditions, but on January 24, it was possible to bring the refrigerator "Coast of Hope" to clean water.
On January 26, the towing "whiskers" broke again, and I had to lose time for the delivery of new ones by helicopter.
On January 31, the Sodruzhestvo floating base was also withdrawn from the ice captivity, the operation ended at 11:00 Vladivostok time.
Notes
- Old maps of Russian cities - from ancient times to the present day (unspecified) ... www.retromap.ru. Date of treatment January 15, 2016.
- The Sea of \u200b\u200bOkhotsk is our everything (unspecified) ... // rg.ru. Retrieved 22 November 2015.
- FAO: World review of highly migratory species and straddling stocks ...
- Peanut Hole scheme
Okhotsk sea located in the northwestern part of the Pacific Ocean off the coast of Asia and is separated from the ocean by the chain of the Kuril Islands and the Kamchatka Peninsula. From the south and west, it is limited by the coast of Hokkaido Island, the eastern coast of Sakhalin Island and the coast of the Asian continent. The sea is significantly elongated from south-west to north-east within a spherical trapezoid with coordinates 43 ° 43 "- 62 ° 42" N. sh. and 135 ° 10 "–164 ° 45" E. The greatest length of the water area in this direction is 2463 km, and the width reaches 1,500 km. The area of \u200b\u200bthe sea surface mirror is 1603 thousand km2, the length coastline - 10 460 km, and the total volume of sea waters - 1316 thousand km3. In their own way geographic location it belongs to the marginal seas of the mixed continental-marginal type. The Sea of \u200b\u200bOkhotsk is connected with the Pacific Ocean by numerous straits of the Kuril island ridge, and with the Sea of \u200b\u200bJapan - through the La Perouse Strait and through the Amur estuary - by the Nevelskoy and Tatarsky straits. The average value of the sea depth is 821 m, and the highest is 3521 m (in the Kuril Basin).
The main morphological zones in the bottom topography are: the shelf (continental and island shoals of Sakhalin Island), the continental slope, on which separate seamounts, depressions and islands are distinguished, and a deep-water basin. The shelf zone (0-200 m) is 180-250 km wide and occupies about 20% of the sea area. A wide and gentle, in the central part of the basin, the continental slope (200-2000 m) occupies about 65%, and the deepest basin (more than 2500 m), located in the southern part of the sea - 8% of the sea area. Within the area of \u200b\u200bthe continental slope, several elevations and depressions are distinguished, where the depths change sharply (the uplift of the Academy of Sciences, the uplift of the Institute of Oceanology and the Deryugin Basin). The bottom of the deep-water Kuril Basin is a flat abyssal plain, and the Kuril Ridge is a natural sill separating the sea basin from the ocean.
The straits of the Amursky Estuary, Nevelskoy in the north and La Perouse in the south connect the Sea of \u200b\u200bOkhotsk with the Sea of \u200b\u200bJapan, and by numerous Kuril straits - with the Pacific Ocean. The chain of Kuril Islands is separated from the island of Hokkaido by the Strait of Treason, and from the Kamchatka Peninsula - by the First Kuril Strait. The straits connecting the Sea of \u200b\u200bOkhotsk with the adjacent areas of the Sea of \u200b\u200bJapan and the Pacific Ocean provide the possibility of water exchange between basins, which, in turn, have a significant impact on the distribution of hydrological characteristics. The straits of Nevelskoy and La Perouse are relatively narrow and shallow, which is the reason for the relatively weak water exchange with the Sea of \u200b\u200bJapan. The straits of the Kuril Island Ridge, which stretches for about 1200 km, on the contrary, are deeper, and their total width is 500 km. The deepest straits are Bussol (2318 m) and Krusenstern (1920 m).
The northwestern coast of the Sea of \u200b\u200bOkhotsk is practically devoid of large bays, and the northern one is significantly indented. The Tauiskaya Bay juts out into it, the shores of which are indented by bays and bays. The bay is separated from the Sea of \u200b\u200bOkhotsk by the Koni Peninsula.
The largest bay in the Sea of \u200b\u200bOkhotsk lies in its northeastern part, extending 315 km into the mainland. This is Shelikhov Bay with Gizhiginskaya and Penzhinskaya bays. Gizhiginskaya and Penzhinskaya bays are separated by the elevated Taigonos Peninsula. In the southwestern part of the Shelikhov Bay, north of the Pyagin Peninsula, there is a small Yamskaya Bay.
The western coast of the Kamchatka Peninsula is leveled and practically devoid of bays.They are complex in shape and form shallow bays on the shores of the Kuril Islands. On the Okhotsk side, the largest bays are located near Iturup Island, which are deep-water and have a very complexly dissected bottom.
Quite a lot of mainly small rivers flow into the Sea of \u200b\u200bOkhotsk, therefore, with a significant volume of its waters, the continental runoff is relatively small. It is equal to about 600 km3 per year, while about 65% of the runoff comes from the Amur River. Other relatively large rivers - Penzhina, Okhota, Uda, Bolshaya (in Kamchatka) - bring much less fresh water to the sea. The runoff comes mainly in spring and early summer. At this time, its greatest influence is felt mainly in the coastal zone, near the estuarine areas of large rivers.
ShoresSea of \u200b\u200bOkhotsk in different areas belong to different geomorphological types, mostly abrasive, altered by the sea, and only on the Kamchatka Peninsula and Sakhalin Island there are accumulative shores. Basically, the sea is surrounded by high and steep shores. In the north and northwest, rocky ledges descend directly to the sea. The shores are low along the Sakhalin Bay. South east coast Sakhalin is low, and the northeast is low. The shores of the Kuril Islands are very steep. The northeastern coast of Hokkaido is mostly low-lying. The coast of the southern part of Western Kamchatka is of the same character, but the shores of its northern part rise somewhat.
By the characteristics of the composition and distribution bottom sedimentsthree main zones can be distinguished: the central one, which is composed mainly of diatomaceous silt, silty-clayey and partially clayey silts; the zone of distribution of hemipelagic and pelagic clays in the western, eastern and northern parts of the Sea of \u200b\u200bOkhotsk; as well as the zone of distribution of different-grained sands, sandstones, gravel and silt - in the northeast of the Sea of \u200b\u200bOkhotsk. Coarse clastic material is ubiquitous, which is the result of ice spread.
The Sea of \u200b\u200bOkhotsk is in the monsoon climatetemperate latitudes. A significant part of the sea in the west juts deep into the mainland and lies relatively close to the cold pole of the Asian land, therefore main source cold for the Sea of \u200b\u200bOkhotsk is located to the west of it. The relatively high ridges of Kamchatka impede the penetration of warm Pacific air. Only in the southeast and in the south is the sea open to the Pacific Ocean and the Sea of \u200b\u200bJapan, from where a significant amount of heat enters it. However, the influence of cooling factors is stronger than that of warming factors, therefore the Sea of \u200b\u200bOkhotsk is generally cold.
In the cold part of the year (from October to April), the sea is affected by the Siberian anticyclone and the Aleutian minimum. The influence of the latter extends mainly to the southeastern part of the sea. This distribution of large-scale baric systems causes strong stable northwestern and north windsoften reaching stormy strength. In winter, the wind speed is usually 10–11 m / s.
In the coldest month - January - the average air temperature in the northwest of the sea is –20 ...– 25 ° С, in the central regions - –10 ...– 15 ° С, and in the southeastern part of the sea - –5 ...– 6 ° C.
In the autumn winter time cyclones of predominantly continental origin. They bring with them an increase in wind, sometimes a decrease in air temperature, but the weather remains clear and dry, since continental air comes from the cooled mainland. In March - April, a restructuring of large-scale baric fields occurs, the Siberian anticyclone collapses, and the Hawaiian maximum increases. As a result, during the warm season (from May to October), the Sea of \u200b\u200bOkhotsk is under the influence of the Hawaiian maximum and an area of \u200b\u200blow pressure located above Eastern Siberia... At the same time, weak southeast winds prevail over the sea. Their speed usually does not exceed 6-7 m / s. These winds are most often observed in June and July, although stronger northwest and northerly winds are occasionally observed during these months. In general, the Pacific (summer) monsoon is weaker than the Asian (winter) monsoon, since the horizontal pressure gradients are smoothed in the warm season.
In summer, the average monthly air temperature in August decreases from the southwest to the northeast (from 18 ° C to 10–10.5 ° C).In the warm season, tropical cyclones - typhoons quite often pass over the southern part of the sea. They are associated with an increase in wind to a storm, which can last up to 5–8 days. The prevalence of southeastern winds in the spring-summer season leads to significant cloudiness, precipitation, fog.
Monsoon winds and stronger winter cooling of the western part of the Sea of \u200b\u200bOkhotsk compared to the eastern are important climatic features of this sea.Geographical position, great length along the meridian, monsoon change of winds and good communication of the sea with the Pacific Ocean through the Kuril Straits are the main natural factorsthat most significantly affect the formation hydrological conditions Sea of \u200b\u200bOkhotsk.
The inflow of the surface waters of the Pacific Ocean into the Sea of \u200b\u200bOkhotsk occurs mainly through the northern straits, in particular through the First Kuril Strait.
In the upper layers of the southern part of the Kuril ridge, the runoff of the Okhotsk Sea waters prevails, and in the upper layers of the northern part of the ridge, the inflow of Pacific waters occurs. In the deep layers, the influx of Pacific waters prevails.
The inflow of Pacific waters significantly affects the distribution of temperature, salinity, the formation of the structure and general circulation of the waters of the Sea of \u200b\u200bOkhotsk.
The following water masses are distinguished in the Sea of \u200b\u200bOkhotsk:
- surface water mass with spring, summer and autumn modifications. It is a thin heated layer 15–30 m thick, which limits the upper maximum of stability, mainly due to temperature;
- the Okhotsk Sea water mass is formed from surface water in winter and in spring, summer and autumn manifests itself in the form of a cold intermediate layer lying between the 40–150 m horizons. This water mass is characterized by a fairly uniform salinity (31–32 ‰) and different temperatures;
- the intermediate water mass is formed mainly due to the discharge of waters along the underwater slopes, within the sea, ranging from 100-150 to 400-700 m, and is characterized by a temperature of 1.5 ° C and a salinity of 33.7 ‰. This mass of water is spread almost everywhere;
- the deep Pacific water mass is the water of the lower part of the warm layer of the Pacific Ocean entering the Sea of \u200b\u200bOkhotsk at horizons below 800-1000 m. This water mass is located at the horizons of 600-1350 m, has a temperature of 2.3 ° C and a salinity of 34.3 ‰.The water mass of the southern basin is of Pacific origin and is the deep water of the northwestern Pacific Ocean near the 2300 m horizon.This water mass fills the basin from the 1350 m horizon to the bottom and is characterized by a temperature of 1.85 ° C and a salinity of 34.7 ‰, which only slightly change with depth.
Water temperature on the sea surface it decreases from south to north. In winter, almost everywhere, the surface layers are cooled to a freezing point of –1.5 ... –1.8 ° С. Only in the southeastern part of the sea does it keep about 0 ° С, and near the northern Kuril straits, under the influence of the Pacific waters, the water temperature reaches 1–2 ° С.
Spring warming up at the beginning of the season is mainly spent on ice melting, only towards the end of it the water temperature begins to rise.In summer, the distribution of water temperature on the sea surface is quite diverse. In August, the warmest (up to 18–19 ° С) waters are adjacent to the island of Hokkaido. In the central regions of the sea, the water temperature is 11–12 ° С. The coldest surface waters are observed near Iona Island, near Cape Pyagina and near the Kruzenshtern Strait. In these areas, the water temperature is kept within 6-7 ° С. The formation of local foci of increased and decreased water temperature 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, the change in temperature with depth is less complex and varied than in the warm seasons.
In winter, in the northern and central regions of the sea, water cooling extends to the levels of 500–600 m. The water temperature is relatively uniform and varies from –1.5 ... –1.7 ° С on the surface to –0.25 ° С at 500– 600 m, deeper it rises to 1–0 ° С, in the southern part of the sea and near the Kuril straits the water temperature from 2.5–3 ° С on the surface drops to 1–1.4 ° С at horizons of 300–400 m and beyond gradually rises to 1.9–2.4 ° С in the bottom layer.
In summer, surface waters are warmed up to temperatures of 10–12 ° С. In the subsurface layers, the water temperature is slightly lower than on the surface. A sharp drop in temperature to –1 ... –1.2 ° С is observed between horizons of 50–75 m, deeper, to horizons of 150–200 m, the temperature rapidly rises to 0.5–1 ° С, and then it rises more smoothly , and at levels 200–250 m is equal to 1.5–2 ° С. Further, the water temperature almost does not change to the bottom. In the southern and southeastern parts of the sea, along the Kuril Islands, the water temperature from 10-14 ° C on the surface drops to 3-8 ° C at the 25 m horizon, then to 1.6-2.4 ° C at the 100 m horizon and up to 1.4–2 ° С 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 in it is negative, and only near the Kuril straits does it have positive values. In different areas of the sea, the depth of the cold intermediate layer is different and varies from year to year.
Distribution salinity in the Sea of \u200b\u200bOkhotsk, relatively little changes with the seasons. Salinity rises in the eastern part, influenced by the Pacific waters, and decreases in the western part, which is freshened by continental runoff. In the western part, the salinity on the surface is 28–31 ‰, and in the east - 31–32 ‰ or 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 \u200b\u200bOkhotsk. At the horizons of 300–400 m in the western part of the sea, salinity is 33.5 а, and in the eastern part it is about 33.8 ‰. At a horizon of 100 m, salinity is 34 ‰ and further to the bottom it increases slightly, only by 0.5–0.6 ‰.In some bays and straits, the salinity and its stratification can 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 regions of the sea covered with ice. The density is somewhat lower in the relatively warm Kuril region. In summer, the water density decreases, its lowest values \u200b\u200bare confined to the zones of influence of coastal runoff, and the highest are observed in the 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 vertical density stratification of waters is created; the density increases especially noticeably at the 25–50 m horizons, which is associated with the warming up of waters in open areas and desalination near the coast.
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 hindered by the maximum stability existing here. In areas with rugged bottom topography, the spread of density mixing to the lower horizons is facilitated by the sliding of waters along the slopes.
Under the influence of winds and the influx of water through the Kuril Strait, characteristic features of a system of non-periodic currents Sea of \u200b\u200bOkhotsk. The main one is the cyclonic system of currents, covering almost the entire sea. It is caused by the prevalence of cyclonic atmospheric circulation over the sea and the adjacent part of the Pacific Ocean. In addition, stable anticyclonic gyres are observed in the sea.
Strong currents bypass the sea along the coastline counterclockwise: the warm Kamchatka Current, the stable East Sakhalin Current, and the rather strong Soya Current.
And finally, one more feature of the Sea of \u200b\u200bOkhotsk water circulation is bilateral stable currents in most of the Kuril straits.The currents on the surface of the Sea of \u200b\u200bOkhotsk are most intense near the western shores of Kamchatka (11–20 cm / s), in the Sakhalin Gulf (30–45 cm / s), in the region of the Kuril straits (15–40 cm / s), above the Kuril Basin (11 –20 cm / s) and during the Soybean (up to 50–90 cm / s).
In the Sea of \u200b\u200bOkhotsk, various types of periodic tidal currents: semi-daily, daily and mixed with a predominance of semi-daily or daily components. The velocities of tidal currents are from a few centimeters to 4 m / s. Far from the coast, the current velocities are low - 5–10 cm / s. In straits, bays and off the coast, their speeds increase significantly. For example, in the Kuril straits, current velocities reach 2–4 m / s.
In general, tidal level fluctuations in the Sea of \u200b\u200bOkhotsk are very significant and have a significant impact on its hydrological regimeespecially in the coastal area.
In addition to tidal fluctuations, the level fluctuations are well developed here. They occur mainly when deep cyclones pass over the sea. Surge rises in the level reach 1.5–2 m. The largest surges were recorded on the coast of Kamchatka and in the Terpeniya Bay.The considerable size and great depths of the Sea of \u200b\u200bOkhotsk, frequent and strong winds over it cause the development of large waves here. The sea is especially stormy in autumn, and in some areas 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 restless 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%.
In normal years, the southern border is 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, owing to the winds, significant masses of ice are carried into it from the north, often accumulating near the Kuril Islands.The ice cover in the Sea of \u200b\u200bOkhotsk lasts for 6–7 months. More than 75% of the sea surface is covered with floating ice. The dense ice of the northern part of the sea presents 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. Part of the ice from the Sea of \u200b\u200bOkhotsk is carried out into the ocean, where it collapses and melts almost immediately.
Forecast resources hydrocarbons The Sea of \u200b\u200bOkhotsk is estimated at 6.56 billion tons in oil equivalent, the explored reserves are over 4 billion tons. The largest deposits on the shelves (along the coast of Sakhalin Island, Kamchatka Peninsula, Khabarovsk Territory and Magadan Region). The most studied are the deposits of Sakhalin Island. Prospecting works on the island's shelf began in the 70s. Twentieth century, by the end of the 90s, seven large fields (6 oil and gas condensate and 1 gas condensate) and a small gas field in the Tatar Strait were discovered on the shelf of Northeast Sakhalin. The total gas reserves on the Sakhalin shelf are estimated at 3.5 trillion m3.
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Vegetation and fauna are very diverse. In terms of stocks of commercial crab, the sea ranks first in the world. Salmon fish are of great value: chum salmon, pink salmon, coho salmon, chinook salmon, sockeye salmon - a source of red caviar. Intensive fishing is carried out for herring, pollock, flounder, cod, navaga, capelin, etc. The sea is inhabited by whales, seals, sea lions, fur seals. There is an increasing interest in shellfish fishing and sea \u200b\u200burchins... Various algae are ubiquitous in the littoral.
In connection with the poor development of the adjacent territories, maritime transport has acquired primary importance. Important sea routes lead to Korsakov on Sakhalin Island, Magadan, Okhotsk and other settlements.The greatest anthropogenic load areas of the Tauiskaya Bay in the northern part of the sea and the shelf areas of Sakhalin Island are exposed. The northern part of the sea receives about 23 tons of oil products annually, 70–80% of which comes from river runoff. Pollutants enter the Tauiskaya Bay from coastal industrial and municipal facilities, and Magadan's effluents enter the coastal zone practically without treatment.
The offshore zone of Sakhalin Island is polluted by coal, oil and gas production enterprises, pulp and paper mills, fishing and processing vessels and enterprises, waste waters of municipal facilities. The annual flow of oil products into the southwestern part of the sea is estimated at about 1.1 thousand tons, with 75–85% of it with river runoff.
Oil carbons enter the Sakhalin Bay mainly with the Amur River runoff; therefore, their maximum concentrations are usually noted in the central and western parts of the Bay along the axis of the Amur waters entering.The eastern part of the sea - the shelf of the Kamchatka Peninsula - is polluted by river runoff, with which the main part of oil-carbons enters the marine environment. In connection with the reduction of work at the fish canning enterprises of the peninsula since 1991, there has been a decrease in the volume of wastewaterdischarged into the coastal zone of the sea.
The northern part of the sea - Shelikhov Bay, Tauiskaya and Penzhinskaya bays - is the most polluted area of \u200b\u200bthe sea with an average content of petroleum hydrocarbons in the water 1–5 times higher than the permissible concentration limit. This is determined not only by the anthropogenic load on the water area, but also by the low average annual water temperatures and, consequently, by the low ability of the ecosystem to self-purify. The highest level of pollution in the northern part of the Sea of \u200b\u200bOkhotsk was recorded in the period from 1989 to 1991.
The southern part of the sea - the La Perouse Strait and the Aniva Bay - are subject to intense oil pollution in the spring-summer period by merchant and fishing fleets. On average, the content of petroleum carbons in the La Perouse Strait does not exceed the permissible concentration limit. Aniva Bay is slightly more polluted. The highest level of pollution in this area was observed near the port of Korsakov, once again confirming that the port is a source of intense pollution of the marine environment.
Pollution of the coastal zone of the sea along the northeastern part of Sakhalin Island is mainly associated with the exploration and production of oil and gas on the shelf of the island and until the end of the 1980s did not exceed the maximum permissible concentration..gif)
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Basic physical and geographical features. In the chain of our Far Eastern seas, it occupies a middle position, juts out quite deeply into the Asian continent, and is separated from the Pacific Ocean by the arc of the Kuril Islands. The Sea of \u200b\u200bOkhotsk has natural boundaries almost everywhere, and only in the southwest from the Sea of \u200b\u200bJapan it is separated by conventional lines: Cape Yuzhny - Cape Tyk and in the La Perouse Strait Cape Krillon - Cape Soya. The southeastern border of the sea goes from Cape Nosyappu (Hokkaido Island) through the Kuril Islands to Cape Lopatka (Kamchatka), with all the passages between about. Hokkaido and Kamchatka are included in the Sea of \u200b\u200bOkhotsk. Within these limits, the sea space extends from north to south from 62 ° 42 ′ to 43 ° 43 ′ N. sh. and from west to east from 134 ° 50 ′ to 164 ° 45 ′ E. e. The sea is significantly elongated from the southwest to the northeast and widened approximately in its central part (Fig. 1).
Figure: 1. Types of shores and bottom relief of the Sea of \u200b\u200bOkhotsk. CONV. see notation
The Sea of \u200b\u200bOkhotsk is one of the largest and deepest seas in our country. Its area is 1603 thousand km 2, volume is 1318 thousand km 3, average depth is 821 m, maximum depth is 3916 m.In terms of geographical location, prevalence of depths of up to 500 m and significant areas occupied by great depths, the Sea of \u200b\u200bOkhotsk belongs to marginal seas of mixed continental-marginal type.
There are few islands in the Sea of \u200b\u200bOkhotsk. The largest border island is Sakhalin. The Kuril ridge has about 30 large, 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 islands and under water. In the latter case, tsunami waves are formed. In addition to the named "marginal" islands in the sea are the islands of Shantarskie, Spafareva, Zavyalova, Yamskie and a small island of Iona - the only one remote from the coast. With a large length, the coastline is relatively weakly indented. At the same time, it forms several large bays (Aniva, Terpeniya, Sakhalinsky, Akademii, Tugursky, Ayan, Shelikhova) and lips (Udskaya, Tauiskaya, Gizhiginskaya and Penzhinskaya).
The straits connecting the Sea of \u200b\u200bOkhotsk with the Pacific Ocean and with the Sea of \u200b\u200bJapan and their depths are very important, as they determine the possibility of water exchange. The straits of Nevelskoy and La Perouse 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 slightly larger - about 40 km, and the maximum depth is 53 m.
At the same time, 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 Sea of \u200b\u200bJapan and the Sea of \u200b\u200bOkhotsk is incomparably less than between the Sea of \u200b\u200bOkhotsk and the Pacific Ocean. However, even the depth of the deepest of the Kuril straits is much less than the maximum depth of the sea, therefore the Kuril ridge is a huge threshold that separates the sea basin from the ocean.
The Bussol and Krusenstern straits are the most important for water exchange with the ocean, since they have the largest area and depth. The depth of the Bussol Strait was indicated above, and the depth of the Krusenstern Strait is 1920 m. The Fries, Fourth Kuril, Rikord and Nadezhda straits, the depths of which are more than 500 m, are of lesser importance. The depths of the remaining straits generally do not exceed 200 m, and the areas are insignificant.
The shores of the Sea of \u200b\u200bOkhotsk, dissimilar in external forms and structure, in different regions belong to different geomorphological types. Fig. 38 shows that for the most part these are abrasive, sea-altered coasts, only in the west of Kamchatka and in the east of Sakhalin there are accumulative shores. Basically, the sea is surrounded by high and steep shores. In the north and northwest, rocky ledges descend directly to the sea. A less high, and then low-lying continental coast approaches the sea near the Sakhalin Bay. The southeastern coast of Sakhalin is low, and the northeast is low. The shores of the Kuril Islands are very steep. The northeastern coast of Hokkaido is mostly low-lying. The coast of the southern part of western Kamchatka is of the same character, but its northern part is distinguished by a slight rise in the coast.
The bottom relief of the Sea of \u200b\u200bOkhotsk is varied and uneven (see Fig. 38). In general, it is characterized by the following main features. 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 \u200b\u200bthe Ayano-Okhotsk coast is about 100 miles, in the area of \u200b\u200bthe Ud Bay - 140 miles. Between the meridians of Okhotsk and Magadan, its width increases to 200 miles. On the western edge of the sea basin is the Sakhalin island bank, on the eastern edge - the Kamchatka continental bank. 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 separate seamounts, depressions and trenches are distinguished.
The deepest southern part of the sea deeper than 2500 m, which is a section of the bed, occupies 8% of the total area. It stretches out in a strip along the Kuril Islands, gradually narrowing from 200 km against about. Iturup up to 80 km against the Kruzenshtern Strait. Great depths and significant bottom slopes distinguish the southwestern part of the sea from the northeastern one, which lies on the continental shelf.
Among the large relief elements of the bottom of the central part of the sea, two seamounts stand out - the Academy of Sciences of the USSR and the Institute of Oceanology. Together with the projection of the continental slope, they determine the division of the sea basin into three basins: the northeastern TINRO depression, the northwestern Deryugin basin, and the southern deep-water Kuril basin. The depressions are connected by grooves: Makarov, P. Schmidt and Lebed. To the northeast of the TINRO Basin, the Shelikhov Gulf trench departs.
The shallowest TINRO depression is located to the 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 to the east of the Sakhalin submarine basement. Its bottom is a flat, elevated plain at the edges, lying on average at a depth of 1700 m, the maximum depth of the depression is 1744 m. The deepest is the Kuril Basin. It is a huge flat plain, lying at a depth of about 3300 m. Its width in the western part is about 120 miles, and its length in the northeast direction is about 600 miles.
The elevation of the Institute of Oceanology has a rounded shape, it is stretched in the latitudinal direction for almost 200 miles, and in the meridional direction for about 130 miles. Minimum depth about 900 m above it. The height of the USSR Academy of Sciences is cut by the tops of underwater valleys. A remarkable feature of the relief of the hills is the presence of flat peaks, occupying a large area.
By its location, the Sea of \u200b\u200bOkhotsk is in the zone of the monsoon climate of temperate latitudes, which is significantly influenced by the physical and geographical features of the sea. Thus, a significant part of it in the west juts deep into the mainland and lies relatively close to the cold pole of the Asian land, therefore the main source of cold for the Sea of \u200b\u200bOkhotsk is in the west, and not in the north. The relatively high ridges of Kamchatka make it difficult for the warm Pacific air to penetrate. Only in the southeast and in the south is the sea open to the Pacific Ocean and the Sea of \u200b\u200bJapan, from where a significant amount of heat enters it. However, the influence of cooling factors is stronger than that of warming, therefore the Sea of \u200b\u200bOkhotsk as a whole is the coldest of the Far Eastern seas. At the same time, its large meridional length determines significant spatial differences in synoptic conditions and meteorological indicators in each season. In the cold part of the year from October to April, the sea is affected by the Siberian anticyclone and the Aleutian minimum. The influence of the latter extends mainly to the southeastern part of the sea. Such a distribution of large-scale baric systems determines the dominance of strong stable northwestern and northern winds, often reaching storm strength. 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 winter Asian 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 °, only in the southeastern part of the sea it is −5-6 °, which is explained by the warming effect Pacific Ocean.
The fall-winter period is characterized by the emergence of cyclones of predominantly continental origin. They entail intensification, winds, and sometimes a decrease in air temperature, but the weather remains clear and dry, since they are supplied with continental air from the cooled mainland of Asia. In March - April, a restructuring of large-scale baric fields occurs. The Siberian anticyclone collapses, and the Honoluli maximum increases. As a result, during the warm season (from May to October), the Sea of \u200b\u200bOkhotsk is under the influence of the Honoluli maximum and the area of \u200b\u200blow pressure located over Eastern Siberia. In accordance with such a distribution of the centers of action of the atmosphere, weak southeast winds prevail over the sea at this time. Their speed usually does not exceed 6-7 m / s. These winds are most often observed in June and July, although stronger northwesterly 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 small. murat gokhan yalciner
In summer, the air warms up unevenly over the entire sea. The average monthly air temperature in August decreases from the southwest to the northeast from 18 ° in the south, to 12-14 ° in the center, and to 10-10.5 ° in the northeast of the Sea of \u200b\u200bOkhotsk. In the warm season, oceanic cyclones often pass over the southern part of the sea, which are associated with an increase in wind to a stormy one, which can last up to 5-8 days. The prevalence of southeastern winds in the spring-summer season leads to significant cloudiness, precipitation, fog. Monsoon winds and stronger winter cooling of the western part of the Sea of \u200b\u200bOkhotsk compared to the eastern part are important climatic features of this sea.
Quite a lot of mainly small rivers flow into the Sea of \u200b\u200bOkhotsk, therefore, with such a significant volume of its waters, the continental runoff is relatively small. It is equal to about 600 km 3 / year, while Amur gives about 65%. Other relatively large rivers - Penzhina, Okhota, Uda, Bolshaya (in Kamchatka) - bring much less fresh water to the sea. It arrives mainly in spring and early summer. At this time, the influence of continental runoff is most noticeable, mainly in the coastal zone, near the mouth areas of large rivers.
Geographical position, great length along the meridian, monsoon change of winds and a good connection between the sea and the Pacific Ocean through the Kuril straits are the main natural factors that most significantly affect the formation of the hydrological conditions of the Sea of \u200b\u200bOkhotsk. The values \u200b\u200bof the arrival and consumption of heat in the sea are mainly determined by the radiation warming up and cooling of the sea. The heat brought by the Pacific waters is of subordinate importance. However, for the water balance of the sea, the arrival and discharge of water through the Kuril straits plays a decisive role. Details and quantitative indicators of water exchange through the Kuril straits have not yet been studied enough, but the main ways of water exchange through the straits are known. The inflow of surface waters from the Pacific Ocean into the Sea of \u200b\u200bOkhotsk occurs mainly through the northern straits, in particular through the First Kuril. In the straits of the middle part of the ridge, both the inflow of the Pacific waters and the runoff of the Okhotsk waters are observed. So, in the surface layers of the Third and Fourth Kuril Straits, apparently, there is a runoff of waters from the Sea of \u200b\u200bOkhotsk, in the bottom layers - an inflow, and in the Bussol Strait, on the contrary: in the surface layers, an inflow, in the deep ones - a runoff. In the southern part of the ridge, mainly through the Catherine and Frisa straits, there is mainly water flow from the Sea of \u200b\u200bOkhotsk. The rate of water exchange through straits can vary significantly. In general, in the upper layers of the southern part of the Kuril ridge, the runoff of the Okhotsk Sea waters prevails, and in the upper layers of the northern part of the ridge, the inflow of Pacific waters occurs. In the deep layers, the inflow of Pacific waters generally prevails.
The influx of Pacific waters largely affects the distribution of temperature, salinity, the formation of the structure and general circulation of the Sea of \u200b\u200bOkhotsk waters.
Hydrological characteristics. Water temperature on the sea surface it generally decreases from south to north. In winter, almost everywhere, the surface layers are cooled to a freezing point of −1.5-1.8 °. Only in the southeastern part of the sea does it keep about 0 °, and near the northern Kuril straits, the water temperature under the influence of the Pacific waters penetrating here reaches 1-2 °.
Spring warming up at the beginning of the season is mainly spent on ice melting, only towards the end of it the water temperature begins to rise. In summer, the distribution of water temperature on the sea surface is rather diverse (Fig. 39). In August, the warmest (up to 18-19 °) waters adjacent to about. Hokkaido. In the central regions of the sea, the water temperature is 11-12 °. The coldest surface waters are observed at about. Iona, near Cape Pyagin and near the Kruzenshtern Strait. In these areas, the water temperature is kept within 6-7 °. The formation of local centers of increased and decreased water temperature 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, the change in temperature with depth is less complex and varied than in the warm seasons. In winter, in the northern and central regions of the sea, water cooling extends to horizons of 100-200 m.The water temperature is relatively uniform and decreases from −1.7-1.5 ° on the surface to −0.25 ° at horizons of 500-600 m, deeper it rises to 1-2 ° in the southern part of the sea, near the Kuril straits, the water temperature from 2.5-3.0 ° on the surface decreases to 1.0-1.4 ° at the horizons of 300-400 m and then gradually rises to 1, 9-2.4 ° at the bottom.
In summer, surface waters are warmed up to temperatures of 10-12 °. In the subsurface layers, the water temperature is slightly lower than on the surface. A sharp decrease in temperature to values \u200b\u200bof -1.0-1.2 ° is observed between horizons of 50-75 m, deeper to horizons of 150-200 m, the temperature rises to 0.5-1.0 °, and then its rise occurs more smoothly and by horizons 200-250 m, it is equal to 1.5-2.0 °. From here the water temperature hardly changes to 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 the 25 m horizon, then to 1.6-2.4 ° at the 100 m horizon and up to 1 , 4-2.0 ° at the bottom. The vertical distribution of temperature in summer is characterized by a cold intermediate layer - the remainder of the winter cooling of the sea (see Fig. 2). In the northern and central regions of the sea, the temperature in it is negative and only near the Kuril straits does it have positive values. In different areas of the sea, the depth of the cold intermediate layer is different and varies from year to year.
Figure: 2. Temperature distribution on the surface and in depth in the Sea of \u200b\u200bOkhotsk
Figure: 3. Distribution of salinity on the surface and in depth in the Sea of \u200b\u200bOkhotsk
Distribution salinity in the Sea of \u200b\u200bOkhotsk, it changes relatively little over the seasons and is characterized by its increase in the eastern part, which is under the influence of the Pacific waters, and a decrease in the western part, which is freshened by the continental runoff (Fig. 3). In the western part, the salinity on the surface is 28-31 ‰, and in the eastern part it is 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 \u200b\u200bOkhotsk. At the horizons of 300-400 m in the western part of the sea, salinity is 33.5 ‰, and in the eastern part about 33.8 ‰. At a horizon of 100 m, salinity is 34.0 ‰ and further to the bottom it increases slightly - only 0.5-0.6 ‰. In some bays and straits, the salinity and its stratification can differ significantly from the open sea, depending on local hydrological conditions.
Temperature and salinity determine the values \u200b\u200band distribution density waters of the Okhotsk Sea. Accordingly, denser waters are observed in winter in the northern and central ice-covered areas of the sea. The density is somewhat lower in the relatively warm Kuril region. In summer, the water density decreases, its lowest values \u200b\u200bare confined to the zones of influence of coastal runoff, and the highest are observed in the areas of distribution of Pacific waters. Density increases with depth. In winter, it rises relatively slightly from the surface to the bottom. In summer, its distribution depends on temperature values \u200b\u200bin the upper layers, and on salinity in the middle and lower layers. In summer, a noticeable vertical density stratification of water is created, the density increases especially significantly at the 25-35-50 m horizons, which is associated with the warming up of waters in open areas and desalination near the coast.
The features of the vertical distribution of oceanological characteristics are largely associated with the development opportunities mixing waters Sea of \u200b\u200bOkhotsk. Wind mixing is carried out during the ice-free season. It proceeds most intensively in spring and autumn, when strong winds blow over the sea, and water stratification is not yet very pronounced. At this time, wind mixing extends to a horizon of 20-25 m from the surface. Strong cooling and powerful ice formation in the autumn-winter time contributes to the development of convection in the Sea of \u200b\u200bOkhotsk. However, it proceeds unevenly in its different regions, which is explained by the features of the bottom topography, climatic differences, the influx of Pacific waters and other factors. Thermal convection in most of the sea penetrates up to 50-60 m, since the summer heating of surface waters, and in the zones of influence of coastal runoff and significant desalination cause vertical stratification of waters, which is most pronounced at the indicated horizons. The increase in the density of surface waters due to cooling and the convection caused by this is not able to overcome the maximum stability located at the mentioned horizons. In the southeastern part of the sea, where the Pacific waters mainly spread, there is a relatively weak vertical stratification; therefore, thermal convection spreads here to horizons of 150-200 m, where it is limited by the density structure of the waters.
Intense ice formation in most of the sea stimulates enhanced thermohaline winter vertical circulation. At depths of up to 250-300 m, it spreads to the bottom, and its penetration to deeper depths is prevented by the maximum stability existing here. In areas with rugged bottom topography, the spread of density mixing to the lower horizons is facilitated by the sliding of waters along the slopes. In general, the Sea of \u200b\u200bOkhotsk is characterized by good mixing of its waters.
The features of the vertical distribution of oceanological characteristics, mainly water temperature, indicate that the Sea of \u200b\u200bOkhotsk is characterized by a subarctic water structure, in which cold and warm intermediate layers are well expressed in summer. A more detailed study of the subarctic structure in this sea has shown that there are Okhotsk, Pacific and Kuril varieties of the subarctic water structure in it. With the same nature of the vertical structure, they have quantitative differences in the characteristics of the water masses.
Based on analysis T, S-curves in combination with consideration of the vertical distribution of oceanological characteristics in the Sea of \u200b\u200bOkhotsk distinguish the following water masses. Surface water masswith spring, summer and autumn modifications. It represents the upper maximum of stability, mainly due to temperature. This water mass is characterized by the values \u200b\u200bof temperature and salinity corresponding to each season, on the basis of which its mentioned modifications are distinguished.
Sea of \u200b\u200bOkhotsk water mass formed in winter from surface water and in spring, summer and autumn manifests itself in the form of a cold intermediate layer flying between the 40-150 m horizons.This water mass is characterized by a fairly uniform salinity (about 32.9-31.0 ‰) and different from place to place temperature. In most of the sea, its temperature is below 0 ° and reaches -1.7 °, and in the Kuril straits, it is higher than 1 °.
Intermediate water mass is formed mainly due to the sinking of waters along the slopes of the bottom, within the sea it is located 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 northwestern part of the sea, Shelikhov Bay and some areas along the Sakhalin coast, where the Sea of \u200b\u200bOkhotsk water mass reaches the bottom. The thickness of the intermediate water layer generally decreases from south to north.
Deep pacific aquatic the mass is water in the lower part of the warm layer of the Pacific Ocean, entering the Sea of \u200b\u200bOkhotsk at horizons below 800-2000 m, that is, below the depth of the waters sinking in the straits, and in the sea it manifests itself as a warm intermediate layer. This water mass is located at the 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 \u200b\u200bof temperature and salinity are observed in the northeastern and partly in the northwestern regions, which is associated here with the rise of waters, and the smallest values \u200b\u200bof the characteristics are characteristic of the western and southern regions, where the waters sink.
The water mass of the South Basin is of Pacific origin and represents the deep water of the northwestern Pacific Ocean from a horizon of 2300 m, corresponding to the maximum depth of the rapids in the Kuril Straits (Bussol Strait). The considered water mass generally fills the named basin from the horizon of 1350 m to the bottom. It 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 \u200b\u200bOkhotsk and the deep Pacific are the main ones and differ from each other not only in thermohaline, but also in hydrochemical and biological indicators.
Under the influence of winds and the influx of water through the Kuril Strait, characteristic features of a system of non-periodic currents Sea of \u200b\u200bOkhotsk (Fig. 4). The main one is the 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 and vast areas of cyclonic water circulation are traced in the sea.
Figure: 4. Currents on the surface of the Sea of \u200b\u200bOkhotsk
At the same time, a narrow strip of stronger coastal currents is quite clearly distinguished, which, continuing each other, as if bypass the coastline of the sea counterclockwise; warm Kamchatka current directed northward to Shelikhov Bay; the flow of the western and then the south-western direction along the northern and north-western coast of the sea; the stable East Sakhalin current flowing to the south; and the rather strong Soya current, entering the Sea of \u200b\u200bOkhotsk through the La Perouse Strait.
On the southeastern periphery of the cyclonic circulation in the Central part of the sea, a branch of the Northeast Current is distinguished, opposite in the direction of the Kuril Current (or Oyashio) in the Pacific Ocean. As a result of the existence of these streams in some of the Kuril straits, stable areas of convergence of currents are formed, which leads to the subsidence 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, one more feature of the circulation of the Sea of \u200b\u200bOkhotsk is bilateral stable currents in most of the Kuril straits.
Non-periodic currents on the surface of the Sea of \u200b\u200bOkhotsk are most intense near the western shores of Kamchatka (11-20 cm / s), in the Sakhalin Gulf (30-45 cm / s), in the region of the Kuril straits (15-40 cm / s), above the Southern Basin ( 11-20 cm / s) and during the Soybean (up to 50-90 cm / s). In the central part of the cyclonic region, the intensity of horizontal transport is much less than in its periphery. In the central part of the sea, velocities vary from 2 to 10 cm / s, with velocities less than 5 cm / s prevailing. A similar picture is observed in Shelikhov Bay, rather strong currents near the coast (up to 20-30 cm / s) and low velocities in the central part of the cyclonic gyre.
In the Sea of \u200b\u200bOkhotsk, periodic (tidal) currents are also well expressed. Here, there are various types of them: semi-daily, daily and mixed with a predominance of semi-daily or daily components. The velocities of tidal currents are different - from a few centimeters to 4 m / s. Far from the coast, current velocities are low (5-10 cm / s). In straits, bays and off the coast, the speed of tidal currents increases significantly, for example, in the Kuril Straits, they reach 2-4 m / s.
Tides The Sea of \u200b\u200bOkhotsk are very complex. The tidal wave enters from the south and southeast from the Pacific Ocean. The semidiurnal wave moves to the north, and at the parallel of 50 ° it splits into two branches: the western one turns to the north-west, forming amphidromic areas north of Cape Terpeniya and in the northern part of the Sakhalin Bay, the eastern one moves towards the Shelikhov Bay, at the entrance to which it appears another amphidromia. The diurnal wave also moves northward, but at the latitude of the northern tip of Sakhalin it is divided into two parts: one enters the Shelikhov Bay, the other reaches the northwestern coast.
In the Sea of \u200b\u200bOkhotsk, there are two main types of tides: diurnal and mixed. The most common are daily tides. They are observed in the Amur estuary, Sakhalin Bay, on the Kuril Islands, off the western coast of Kamchatka and in the Penzhinsky Bay. Mixed tides are observed on the northern and northwestern coasts of the sea and in the region of the Shantar Islands.
The greatest value of tides was noted in Penzhinskaya Bay near Astronomical Cape (up to 13 m). These are the highest tides for the entire coast of the USSR. In second place is the region of the Shantar Islands, where the tide value exceeds 7 m. The tides in the Sakhalin Gulf and in the Kuril straits are very significant. In the northern part of the sea, the magnitude of tides reaches 5 m. The smallest tides were noted off the eastern coast of Sakhalin, in the area of \u200b\u200bthe La Perouse Strait. In the southern part of the sea, the magnitude of tides is 0.8-2.5 m. In general, tidal fluctuations in the level in the Sea of \u200b\u200bOkhotsk are very significant and have a significant impact on its hydrological regime, especially in the coastal zone.
In addition to tidal surges, there are well-developed surge level fluctuations... They occur mainly when deep cyclones pass over the sea. Surge rises in the level reach 1.5-2 m. The largest surges were recorded on the coast of Kamchatka and in the Terpeniya Bay.
The considerable size and great depths of the Sea of \u200b\u200bOkhotsk, frequent and strong winds over it cause the development of large waves here. The sea is especially stormy in autumn, and in iceless regions also 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 southeastern regions of the sea, where the average frequency of storm waves is 35 -50%, and in the north-western part it decreases to 25-30%. With strong waves in the straits between the Kuril Islands and between the Shantar Islands, a crowd is formed.
Harsh and long winters with strong northwest winds contribute to the development of intense ice formationin the Sea of \u200b\u200bOkhotsk. The ice of the Sea of \u200b\u200bOkhotsk is exclusively local. There are both fixed ice (fast ice) and floating ice, which is the main form of sea ice. In varying amounts of ice is found in all areas of the sea, but in summer the entire sea is cleared of ice. An exception is the region of the Shantar Islands, where ice can persist in summer.
Ice formation begins in November in the bays and inlets of the northern part of the sea, in the coastal part of about. Sakhalin and Kamchatka. Then ice appears in the open sea. In January and February, ice covers the entire northern and middle part of the sea. In ordinary years, the southern boundary of the relatively stable ice cover runs, bending to the north, from the La Perouse Strait to Cape Lopatka. The extreme southern part of the sea never freezes. However, owing to the winds, significant masses of ice are carried into it from the north, often accumulating near the Kuril Islands.
From April to June, the ice cover breaks down and gradually disappears. On average, the sea ice disappears in late May - early June. Due to the currents and coastal configuration, the northwestern part of the sea is most of all clogged with ice, which remains there until July. Consequently, the ice cover in the Sea of \u200b\u200bOkhotsk persists for 6-7 months. More than three quarters of the sea surface is covered with floating ice. The dense ice of the northern part of the sea presents a serious obstacle 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 are classified as areas with low ice coverage, where ice stays on average no more than three months a year. The thickness of the ice growing during the winter reaches 0.8-1.0 m. Strong storms, tidal currents break the ice cover in many areas of the sea, forming hummocks and large floodplains. In the open part of the sea, continuous motionless ice is never observed, usually here ice drifts in the form of vast fields with numerous openings. Part of the ice from the Sea of \u200b\u200bOkhotsk is carried into the ocean, where it collapses and melts almost immediately. In severe winters, floating ice is pressed against the Kuril Islands by north-westerly winds and clogs up some straits. Thus, in winter, there is no place in the Sea of \u200b\u200bOkhotsk where meeting with ice would be completely excluded.
Hydrochemical conditions. Due to constant water exchange with the Pacific Ocean through the deep Kuril straits chemical composition waters of the Sea of \u200b\u200bOkhotsk, in general, does not differ from the ocean. The values \u200b\u200band distribution of dissolved gases and nutrients in the open sea areas are determined by the influx of Pacific waters, and in the coastal part, coastal runoff has a certain effect.
The Sea of \u200b\u200bOkhotsk is rich in oxygen, but its content is not the same in different regions of the sea and varies with depth. A large amount of oxygen is dissolved in the waters of the northern and central parts of the sea, which is explained by the richness of phytoplankton here, which produces oxygen. In particular, in the central part of the sea, the development of plant organisms is associated with the rise of deep waters in the zones of convergence of currents. The waters of the southern regions of the sea contain less oxygen, since comparatively phytoplankton-poor Pacific waters enter here. The highest content (7-9 ml / l) of oxygen is noted in the surface layer, deeper it gradually decreases and at a horizon of 100 m is equal to 6-7 ml / l, and at a horizon of 500 m - 3.2-4.7 ml / l, further, the amount of this gas decreases very rapidly with depth and reaches a minimum (1.2-1.4 ml / l) at horizons of 1000-1300 m, but in deeper layers it increases to 1.3-2.0 ml / l. The oxygen minimum is confined to the deep Pacific water mass.
The surface layer of the sea contains 2-3 μg / l of nitrites and 3-15 μg / l of nitrates. With depth, their concentration increases, and the content of nitrites reaches a maximum at horizons of 25-50 m, and the amount of nitrates here sharply increases, but the highest values \u200b\u200bof these substances are noted at horizons of 800-1000 m, from where they slowly decrease to the bottom. The vertical distribution of phosphates is characterized by an increase in their content with depth, especially noticeable from horizons of 50-60 m, and the maximum concentration of these substances is observed in the bottom layers. In general, the amount of nitrites, nitrates and phosphates dissolved in sea waters increases from north to south, which is mainly associated with the rise of deep waters. Local features of hydrological and biological conditions (water circulation, tides, degree of development of organisms, etc.) form the regional hydrochemical features of the Sea of \u200b\u200bOkhotsk.
Household use. The national economic significance of the Sea of \u200b\u200bOkhotsk is determined by the use of its natural resources and marine transportation... The main wealth of this sea is game animals, first of all fish. Here, mainly its most valuable species are caught - salmon (chum, pink salmon, sockeye salmon, coho salmon, chinook salmon) and their caviar. At present, salmon stocks have decreased, therefore, their production has decreased. Fishing for this fish is limited. In addition, herring, cod, flounder and other types of marine fish are caught in the sea in limited quantities. The Sea of \u200b\u200bOkhotsk is the main area for crab fishing. Squid is hunted in the sea. One of the largest herds of fur seals is concentrated on the Shantar Islands, the production of which is strictly regulated.
Sea transport lines connect the Okhotsk ports of Magadan, Nagaevo, Ayan, Okhotsk with other Soviet and foreign ports. Various cargoes come here from different regions of the Soviet Union and foreign countries.
To a large extent, the studied Sea of \u200b\u200bOkhotsk still needs to solve various natural problems. In terms of their hydrological aspects, studies of water exchange between the sea and the Pacific Ocean, general circulation, including vertical water movements, their fine structure and eddy-like movements, ice conditions, especially in the forecast direction of the timing of ice formation, the direction of ice drift, etc., occupy an essential place. The solution of these and other problems will contribute to the further development of the Sea of \u200b\u200bOkhotsk.
The Sea of \u200b\u200bOkhotsk juts out rather deep into the land and is noticeably elongated from the southwest to the northeast. It has coastal lines almost everywhere. It is separated from the Sea of \u200b\u200bJapan by about. Sakhalin and the conditional lines of Cape Sushchev - Cape Tyk (Strait of Nevelskoy), and in the La Perouse Strait - Cape Soya - Cape Krillon. The southeastern border of the sea runs from Cape Nosappu (Hokkaido Island) and through the Kuril Islands to Cape Lopatka (Kamchatka Peninsula).
The Sea of \u200b\u200bOkhotsk is one of the largest and deep seas the world. Its area is 1 603 thousand km 2, volume - 1 316 thousand km 3, average depth - 821 m, maximum depth - 3 521 m.
The Sea of \u200b\u200bOkhotsk belongs to the marginal seas of the mixed continental-oceanic type. It is separated from the Pacific Ocean by the Kuril ridge, which has about 30 large, 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 islands and under water. In the latter case, tsunami waves are often formed. In the sea there is a group of Shantarsky islands, Spafareva, Zavyalov, Yamskie islands and a small Iona island - the only one remote from the coast. With a great length, the coastline is relatively weakly indented. At the same time, it forms several large bays (Aniva, Terpeniya, Sakhalinsky, Akademii, Tugursky, Ayan, Shelikhova) and lips (Udskaya, Tauiskaya, Gizhiginskaya and Penzhinskaya).
The straits of Nevelskoy and La Perouse 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, the 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 Sea of \u200b\u200bJapan and the Sea of \u200b\u200bOkhotsk is incomparably less than between the Sea of \u200b\u200bOkhotsk and the Pacific Ocean.
However, even the depth of the deepest of the Kuril straits is much less than the maximum depth of the sea, and therefore the Kuril ridge is a huge threshold that separates the sea basin from the ocean.
The Bussol and Krusenstern straits are the most important for water exchange with the ocean, since they have the largest area and depth. The depth of the Bussol Strait was indicated above, and the depth of the Krusenstern Strait is 1920 m. The Fries, Fourth Kuril, Rikord and Nadezhda straits, the depths of which are more than 500 m, are of lesser importance. The depths of the remaining straits do not generally exceed 200 m, and their areas are insignificant.
On distant shores
The shores of the Sea of \u200b\u200bOkhotsk in different regions belong to different geomorphological types. For the most part, these are abrasive, sea-altered coasts, and only Kamchatka and Sakhalin are accumulative shores. Basically, the sea is surrounded by high and steep shores. In the north and northwest, rocky ledges descend directly to the sea. The shores are low along the Sakhalin Bay. The southeastern coast of Sakhalin is low, and the northeast is low. The shores of the Kuril Islands are very steep. The northeastern coast of Hokkaido is mostly low-lying. The coast of the southern part of Western Kamchatka has the same character, but the coast of its northern part rises slightly.
Shores of the Sea of \u200b\u200bOkhotsk
Bottom relief
The relief of the bottom of the Sea of \u200b\u200bOkhotsk is diverse. The northern part of the sea is a continental shelf - an underwater continuation of the Asian continent. The width of the continental shoal in the area of \u200b\u200bthe Ayano-Okhotsk coast is about 185 km, in the area of \u200b\u200bthe 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 basin of the sea there is an island bank of Sakhalin, on the east - a bank 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 separate seamounts, 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 sea area. It stretches out in a strip along the Kuril Islands and gradually narrows from 200 km against about. Iturup up to 80 km against the Kruzenshtern Strait. Great depths and significant slopes of the bottom distinguish the southwestern part of the sea from the northeastern one, which lies on the continental shelf.
Of the large relief elements of the bottom of the central part of the sea, two seamounts 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 one - the TINRO depression, the northwestern one - the Deryugin depression, and the southern deep-water - the Kuril depression. The depressions are connected by grooves: Makarov, P. Schmidt and Lebed. To the northeast of the TINRO Basin, the Shelikhov Gulf trench departs.
The least deep is the TINRO depression, located to the 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 to the east of the Sakhalin submarine base. Its bottom is a flat, elevated plain at the edges, lying on average at a depth of 1700 m, the maximum depth of the depression is 1744 m.
The deepest is the Kuril depression. It is a huge flat plain lying at a depth of about 3300 m. Its width in the western part is about 212 km, its length in the northeastern direction is about 870 km.
Topography of the bottom and current of the Sea of \u200b\u200bOkhotsk
Currents
Under the influence of winds and the influx of water through the Kuril straits, characteristic features of the system of non-periodic currents of the Sea of \u200b\u200bOkhotsk are formed. The main one is the cyclonic system of currents, covering almost the entire sea. It is due to the prevalence of cyclonic atmospheric circulation over the sea and the adjacent Pacific Ocean. In addition, stable anticyclonic gyres are traced in the sea: west of the southern tip of Kamchatka (approximately between 50-52 ° N and 155-156 ° E); over the TINRO depression (55-57 ° N and 150-154 ° E); in the area of \u200b\u200bthe Southern Basin (45-47 ° N and 144-148 ° E). In addition, a vast area of \u200b\u200bcyclonic 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 bypass the sea along the coastline counterclockwise: warm Kamchatka current, directed northward into Shelikhov Bay; flow of the western and then south-western direction along the northern and northwestern shores of the sea; the stable East Sakhalin current flowing to the south; and the rather strong Soya current, entering the Sea of \u200b\u200bOkhotsk through the La Perouse Strait.
On the southeastern periphery of the cyclonic circulation in the central part of the sea, a branch of the Northeast Current is distinguished, opposite to the Kuril Current in the Pacific Ocean. As a result of the existence of these flows in some of the Kuril straits, stable areas of convergence of currents are formed, which leads to a sinking 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, one more feature of the Sea of \u200b\u200bOkhotsk water circulation is bilateral stable currents in most of the Kuril straits.
Surface currents on the surface of the Sea of \u200b\u200bOkhotsk are most intense near the western shores of Kamchatka (11-20 cm / s), in the Sakhalin Gulf (30-45 cm / s), in the region of the Kuril straits (15-40 cm / s), above the Southern Basin ( 11-20 cm / s) and during the Soybean (up to 50-90 cm / s). In the central part of the cyclonic region, the intensity of horizontal transport is much less than in its periphery. In the central part of the sea, velocities vary from 2 to 10 cm / s, with velocities less than 5 cm / s prevailing. A similar picture is observed in Shelikhov Bay: rather strong currents near the coast (up to 20-30 cm / s) and low velocities in the central part of the cyclonic circulation.
In the Sea of \u200b\u200bOkhotsk, various types of periodic tidal currents are well expressed: semidiurnal, diurnal and mixed, with a predominance of semidiurnal or diurnal components. The speed of tidal currents is from a few centimeters to 4 m / s. Far from the coast, the current velocities are small - 5-10 cm / s. In straits, bays and off the coast, their speeds increase significantly. For example, in the Kuril Straits, current velocities reach 2-4 m / s.
The tides of the Sea of \u200b\u200bOkhotsk are very complex. The tidal wave enters from the south and southeast from the Pacific Ocean. The semidiurnal wave moves to the north, and at the parallel of 50 ° it is divided into two parts: the western one turns to the north-west, the eastern one moves to the 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 the Shelikhov Bay, the other reaches the northwestern coast.
Diurnal tides are most widespread in the Sea of \u200b\u200bOkhotsk. 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 Penzhinsky Bay. Mixed tides are noted on the northern and northwestern coasts of the sea and in the region of the Shantar Islands.
The greatest value of tides (up to 13 m) was recorded in the Penzhinskaya Bay (Cape Astronomical). In the area of \u200b\u200bthe Shantar Islands, the tide value 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.
Seal rookery
The smallest tides were noted off the eastern coast of Sakhalin, in the area of \u200b\u200bthe 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 \u200b\u200bOkhotsk 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 well developed here. They occur mainly when deep cyclones pass over the sea. Surge rises in the level reach 1.5-2 m. The largest surges were recorded on the coast of Kamchatka and in the Terpeniya Bay.
The considerable size and great depths of the Sea of \u200b\u200bOkhotsk, frequent and strong winds over it cause the development of large waves here. The sea is especially stormy in autumn, and in iceless regions also 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 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%. With strong waves in the straits between the Shantar Islands, a crowd is formed.
Climate
The Sea of \u200b\u200bOkhotsk is located in the monsoon climate zone of temperate latitudes. A significant part of the sea in the west juts deep into the mainland and lies relatively close to the cold pole of the Asian land, so the main source of cold for the Sea of \u200b\u200bOkhotsk is to the west of it. The relatively high ridges of Kamchatka make it difficult for the warm Pacific air to penetrate. Only in the southeast and in the south is the sea open to the Pacific Ocean and the Sea of \u200b\u200bJapan, from where a significant amount of heat enters it. However, the influence of cooling factors is stronger than that of warming, therefore the Sea of \u200b\u200bOkhotsk is generally cold. At the same time, due to the large meridional extent, significant differences arise here in the synoptic situation and meteorological conditions. In the cold part of the year (from October to April), the sea is affected by the Siberian anticyclone and the Aleutian minimum. The influence of the latter extends mainly to the southeastern part of the sea. This distribution of large-scale baric systems causes strong, sustained northwesterly and northerly winds, often reaching stormy 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 winter Asian 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 the central regions –10–15 °, and in the southeastern part of the sea it is –5–6 °.
In the autumn-winter time, cyclones of predominantly continental origin come to the sea. They bring with them an increase in wind, sometimes a decrease in air temperature, but the weather remains clear and dry, since continental air comes from the cooled mainland. In March - April, a restructuring of large-scale baric fields occurs. The Siberian anticyclone collapses, and the Hawaiian maximum increases. As a result, during the warm season (from May to October), the Sea of \u200b\u200bOkhotsk is under the influence of the Hawaiian maximum and the area of \u200b\u200blow pressure located over Eastern Siberia. At this time, weak southeastern winds prevail over the sea. Their speed usually does not exceed 6-7 m / s. These winds are most often observed in June and July, although stronger northwesterly and northerly winds are sometimes observed during these months. In general, the Pacific (summer) monsoon is weaker than the Asian (winter) monsoon, since the horizontal pressure gradients are smoothed in the warm season.
In summer, the average monthly air temperature in August decreases from the southwest (from 18 °) to the northeast (up 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 an increase in wind to a storm, which can last up to 5-8 days. The prevalence of southeastern winds in the spring-summer season leads to significant cloudiness, precipitation, fog.
Monsoon winds and stronger winter cooling of the western part of the Sea of \u200b\u200bOkhotsk compared to the eastern part are important climatic features of this sea.
Quite a lot of mainly small rivers flow into the Sea of \u200b\u200bOkhotsk, therefore, with a significant volume of its waters, the continental runoff is relatively small. It is equal to about 600 km 3 / year, while about 65% of the runoff is provided by the Amur. Other relatively large rivers - Penzhina, Okhota, Uda, Bolshaya (in Kamchatka) - bring much less fresh water to the sea. Runoff comes mainly in spring and early summer. At this time, its greatest influence is felt mainly in the coastal zone, near the estuarine areas of large rivers.
Hydrology and water circulation
Geographical position, great length along the meridian, monsoon change of winds and a good connection between the sea and the Pacific Ocean through the Kuril straits are the main natural factors that most significantly affect the formation of the hydrological conditions of the Sea of \u200b\u200bOkhotsk. The values \u200b\u200bof the arrival and consumption of heat in the sea are mainly determined by the rational warming up and cooling of the sea. The heat brought by the Pacific waters is of subordinate importance. However, for the water balance of the sea, the arrival and discharge of water through the Kuril straits plays a decisive role.
The inflow of surface waters from the Pacific Ocean into the Sea of \u200b\u200bOkhotsk occurs mainly through the northern straits, in particular through the First Kuril. In the straits of the middle part of the ridge, both the inflow of the Pacific waters and the runoff of the Okhotsk waters are observed. So, in the surface layers of the Third and Fourth straits, apparently, there is a runoff of waters from the Sea of \u200b\u200bOkhotsk, in the bottom layers - an inflow, and in the Bussol Strait - on the contrary: in the surface layers - an inflow, in the deep ones - a runoff. In the southern part of the ridge, mainly through the Catherine and Frisa straits, there is mainly water flow from the Sea of \u200b\u200bOkhotsk. The rate of water exchange through straits can vary significantly.
In the upper layers of the southern part of the Kuril ridge, the runoff of the Okhotsk Sea waters prevails, and in the upper layers of the northern part of the ridge, the inflow of Pacific waters occurs. In the deep layers, the influx of Pacific waters prevails.
Water temperature and salinity
The inflow of Pacific waters significantly affects the distribution of temperature, salinity, structure formation and general circulation of the Sea of \u200b\u200bOkhotsk waters. It is characterized by a subarctic structure of waters, in which cold and warm intermediate layers are well expressed in summer. A more detailed study of the subarctic structure in this sea has shown that there are Okhotsk, Pacific and Kuril varieties of the subarctic water structure in it. With the same nature of the vertical structure, they have quantitative differences in the characteristics of the water masses.
The following water masses are distinguished in the Sea of \u200b\u200bOkhotsk:
surface water mass with spring, summer and autumn modifications. It is a thin heated layer 15-30 m thick, which limits the upper maximum of stability, mainly due to temperature. This water mass is characterized by the values \u200b\u200bof temperature and salinity corresponding to each season;
the Okhotsk Sea water mass is formed in winter from surface water and in spring, summer and autumn it manifests itself in the form of a cold intermediate layer lying between the horizons of 40-150 m. This water mass is characterized by a rather uniform salinity (31-32.9 ‰) and different temperatures. In most of the sea, its temperature is below 0 ° and reaches -1.7 °, and in the region of the Kuril straits, it is higher than 1 °;
the intermediate water mass is formed mainly due to the sinking of waters along the underwater slopes, ranging from 100-150 to 400-700 m within the sea, 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 \u200b\u200bOkhotsk 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 water from the lower part of the warm layer of the Pacific Ocean entering the Sea of \u200b\u200bOkhotsk at horizons below 800-1000 m, i.e. below the depth of the waters sinking in the straits, and in the sea it manifests itself in the form of a warm intermediate layer. This water mass is located at the 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 \u200b\u200bof temperature and salinity are observed in the northeastern and partly in the northwestern regions, which is associated here with the rise of waters, and the smallest values \u200b\u200bof the characteristics are characteristic of the western and southern regions, where the waters sink.
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 2300 m horizon, i.e. horizon corresponding to the maximum depth of the sill in the Kuril Straits, located in the Bussol Strait. This water mass fills the basin from the 1350 m horizon 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 \u200b\u200bOkhotsk and the deep Pacific are the main ones; they differ from each other not only in thermohaline, but also in hydrochemical and biological indicators.
The sea surface temperature decreases from south to north. In winter, almost everywhere, the surface layers are cooled to a freezing point of –1.5–1.8 °. Only in the southeastern part of the sea does it keep about 0 °, and near the northern Kuril straits, under the influence of the Pacific waters, the water temperature reaches 1-2 °.
Spring warming up at the beginning of the season is mainly spent on ice melting, only towards the end of it the water temperature begins to rise.
In summer, the distribution of water temperature on the sea surface is quite diverse. In August, the warmest (up to 18-19 °) waters adjacent to about. Hokkaido. In the central regions of the sea, the water temperature is 11-12 °. The coldest surface waters are observed at about. Iona, near Cape Pyagin and near the Kruzenshtern Strait. In these areas, the water temperature is kept within 6-7 °. The formation of local centers of increased and decreased water temperature 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, the change in temperature with depth is less complex and varied than in the warm seasons.
In winter, in the northern and central regions of the sea, water cooling extends to the horizons of 500-600 m.The water temperature is relatively uniform and varies from -1.5-1.7 ° at the surface to -0.25 ° at the horizons of 500-600 m, deeper it 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 the horizons of 300-400 m and then gradually rises to 1.9-2 , 4 ° in the bottom layer.
In summer, surface waters are warmed up to temperatures 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 the horizons of 50-75 m, deeper, to horizons of 150-200 m, the temperature rises rapidly to 0.5 - 1 °, and then it rises more smoothly, and at the horizons 200 - 250 m is equal to 1.5 - 2 °. Further, the water temperature almost does not change to 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 the 25 m horizon, then to 1.6-2.4 ° at the 100 m horizon and up 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 in it is negative, and only near the Kuril straits does it have 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 \u200b\u200bOkhotsk varies relatively little over the seasons. Salinity rises in the eastern part, which is influenced by the Pacific waters, and decreases in the western part, which is desalinated by the 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 \u200b\u200bOkhotsk. At the horizons of 300-400 m in the western part of the sea, salinity is 33.5 ‰, and in the eastern - about 33.8 ‰. At a horizon of 100 m, salinity is 34 ‰ and further to the bottom it increases slightly, by only 0.5-0.6 ‰.
In some bays and straits, the salinity 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 regions of the sea covered with ice. The density is somewhat lower in the relatively warm Kuril region. In summer, the water density decreases, its lowest values \u200b\u200bare confined to the zones of influence of coastal runoff, and the highest are observed in the 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 vertical density stratification of water is created, the density increases especially noticeably at the horizons of 25-50 m, which is associated with the warming up of waters in open areas and desalination near the coast.
Wind mixing is carried out during the ice-free season. It proceeds most intensively in spring and autumn, when strong winds blow over the sea, and water stratification is not yet very pronounced. At this time, wind mixing spreads to horizons of 20-25 m from the surface.
Intense ice formation in 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 hindered by the maximum stability existing here. In areas with rugged bottom topography, the spread of density mixing to the lower horizons is facilitated by the sliding of waters along the slopes.
Ice cover
Harsh 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 \u200b\u200bOkhotsk is exclusively a 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. An exception is the region of the Shantar Islands, where ice can persist in summer.
Ice formation begins in November in the bays and inlets of the northern part of the sea, in the coastal part of about. Sakhalin and Kamchatka. Then ice appears in the open sea. In January and February, ice covers the entire northern and middle part of the sea.
In normal years, the southern boundary 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, owing to the winds, significant masses of ice are carried into it from the north, often accumulating near the Kuril Islands.
From April to June, the ice cover breaks down and gradually disappears. On average, the sea ice disappears in late May - early June. Due to the currents and coastal configuration, the northwestern part of the sea is most of all clogged with ice, which persists until July. The ice cover in the Sea of \u200b\u200bOkhotsk lasts for 6-7 months. More than 3/4 of the sea surface is covered with floating ice. The dense ice of the northern part of the sea presents 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 are classified as areas with low ice coverage: here ice stays on average no more than three months a year. The thickness of the ice growing during the winter reaches 0.8-1 m.
Strong storms, tidal currents break up the ice cover in many areas of the sea, forming hummocks and large openings. In the open part of the sea, continuous stationary ice is never observed, usually here the ice is drifting, in the form of vast fields with numerous openings.
Part of the ice from the Sea of \u200b\u200bOkhotsk is carried into the ocean, where it collapses and melts almost immediately. In severe winters, floating ice is pressed against the Kuril Islands by north-westerly winds and clogs up some straits.
Economic value
There are about 300 species of fish in the Sea of \u200b\u200bOkhotsk. Of these, about 40 species are commercial. The main commercial fish are pollock, herring, cod, navaga, flounder, sea bass, capelin. Catches of salmon (chum salmon, pink salmon, sockeye salmon, coho salmon, chinook salmon) are small.
Geographical position and boundaries of the Sea of \u200b\u200bOkhotsk
The Sea of \u200b\u200bOkhotsk is located in the northwestern part of the Pacific Ocean and, in terms of its geographical position, belongs to the type of marginal seas. It washes the shores of Asia in the north and is separated from the ocean in the southeast by the ridges of the Kuril Islands and the Kamchatka Peninsula. Its western border is drawn along the eastern coast of about. Sakhalin and about. Hokkaido.
Geographical position of the Sea of \u200b\u200bOkhotsk
Sea straits
The straits of the Amur estuary, Nevelskoy in the north and La Perouse in the south connect the Sea of \u200b\u200bOkhotsk with the Sea of \u200b\u200bJapan, and the numerous Kuril straits with the Pacific Ocean. The chain of the Kuril Islands is separated from about. Hokkaido Strait Treason, and from the Kamchatka Peninsula - the First Kuril Strait. The deepest straits of the island chain are Bussol and Krusenstern. Of the others, the largest straits are: Catherine, Frisa, Rikorda, Fourth Kuril. According to N.N.Zubov's classification, the Sea of \u200b\u200bOkhotsk belongs to the basin seas, since the depth of the straits is much less than the maximum depths of the bottom of the basin.
Coastline
The coastline of the Sea of \u200b\u200bOkhotsk has complex outlines. Its bends, connected with the protrusions of large capes and peninsulas, form bays and lips. It is most sinuous in the southwestern and northeastern parts of the sea. In the southwest, the largest are Aniva and Terpeniya bays, separated from the open sea by the Tonino-Anivsky and Terpeniya peninsulas, respectively. In the northeast about. Sakhalin is poorly indented, but on the coast, in close proximity to the sea, there is a chain of large lagoons called bays: Lunsky, Nabilsky, Nyisky, Chayvo, Piltun. These lagoons are separated by spits, between which there are narrow shallow passages. The lagoons are shallow and in most cases covered with algae. North of the hall. Piltun along the east coast of about. Sakhalin is a chain of lakes and lagoons, which are usually rounded and relatively small in size. Sakhalin Bay juts out 100 km between the north of the island. Sakhalin and the mainland coast. It is bordered by Cape Elizabeth in the east and Cape Alexandra in the west, the width of the bay between them is about 200 km. Two smaller bays protrude into the eastern coast of the Sakhalin Bay: Pomr 'and Baikal, and into the western coast - the bays of Ekaterina, Reineke, Shchastya, etc.
From the Sakhalin Bay to the Udskaya Bay there is the most indented section of the coast with numerous large bays: Alexandra, Akademiya, into the shores of which, in turn, the bays of Nikolai, Ulbansky and Konstantin are wedged; Tugursky, separated from the hall. Academy of the Tugur Peninsula. The northwestern coast of the Sea of \u200b\u200bOkhotsk is practically devoid of large bays, and the northern one is significantly indented. The Tauiskaya Bay juts out into it, the shores of which are indented by bays and bays (Motykleisky, Akhmatonsky and Odyan bays). The bay is separated from the Sea of \u200b\u200bOkhotsk by the Koni Peninsula. Of the smaller bays on the northern coast of the Sea of \u200b\u200bOkhotsk, the Eirineyskaya Bay and the bays of Ushki, Sheltinga, Zabiyaka, Babushkina, and Kekurny should be noted. The largest bay in the Sea of \u200b\u200bOkhotsk lies in its northeastern part, extending 315 km into the mainland. This is the hall. Shelikhov from the Gizha and Penzhinsky lips. The southern border of the hall. Shelikhov is a line connecting Cape Tolstoy on the P'ya-gina Peninsula with Cape Utkholoksky on the Kamchatka Peninsula. Gizhinskaya and Penzhinskaya bays are separated by the elevated Taigonos Peninsula. The Penzhinskaya Bay narrows sharply to 40 km by the Elistratov Peninsulas in the west and the Mametchinsky Peninsulas in the east. This narrowness is called the throat. In the southwestern part of the hall. Shelikhov, north of the Pyagin Peninsula, there is a small Yamskaya Bay with the Perevalochny and Malka-Chansky bays. The western coast of the Kamchatka Peninsula is leveled and practically devoid of bays. They are complex in shape and form shallow bays on the shores of the Kuril Islands. On the Okhotsk side, the largest bays are located near Iturup: Dobroe Beginning, Kuibyshevsky, Kurilsky, Prostor, as well as Lion's Mouth and others. The bays are deep and have a very dissected bottom.
Islands
The islands in the Sea of \u200b\u200bOkhotsk are very diverse both in size and shape, and in origin. There are single islands and archipelagos, the islands in which are located in a compact group or elongated in the form of a ridge. The mainland islands and the islands of the transition zone are distinguished. The mainland islands are land masses located within the same block of the earth's crust with the mainland. The islands of the transition zone include linear-elongated archipelagos crowning the ridges of powerful curved underwater ridge-cordilleras. They are called island arcs. King notes a characteristic pattern in the distribution of island chains in the transition zone. They are usually double. The concave inner ridge is occupied by volcanic edifices, and the outer ridge is occupied by the drained projections of the folded base of the Cordillera. Small islands are known from the mainland islands off the coast of East Sakhalin: Tyuleniy and the Rock of Danger Stone. Tyuleniy Island has a flat top and steep shores. An accumulative surface streamer departs from the southern tip. Rock Stone of Danger - a small group of bare stones in the pr. La Perouse.
Iona Island is located 200 km north of the island. Sakhalin. Its height is 150 m, the shores are rocky and almost steep. The Shantar Islands lie in the northwest of the Sea of \u200b\u200bOkhotsk. They are an archipelago of 15 islands with an area of \u200b\u200babout 2,500 km. The largest islands: Bolshoy Shantar (area 1790 km2), Feklistova (about 400 km2), Maly Shantar (about 100 km2), Belichy (about 70 km2). The climate on the islands is harsh. Of the islands on the northern coast, the most significant are located in the Taui Bay. These are the Zavyalov and Spafaryev islands. Spafareva Island rises to 575 m, and about. Zavyalova is mountainous and reaches a height of 1130 m. Its slopes are covered with bushes, the banks are rocky. In the Shelikhov Hall, the islands are located close to the coast and are small in size. The most distant from the coastline are Yamskie (Atykan, Matykil), as well as small islands of Kokontse, Baran, Hatemalyu. They are located at a distance of up to 20 km east of the Pyagin Peninsula. Small islands: Third, Extreme, Dobrzhansky, Rovny, Zubchaty, Konus, Chemeivytegartynup - are located in the Penzhinsky Bay. There is only one noticeable island off the coast of western Kamchatka - Ptichiy, located to the north of Cape Khairyuzovo. The garland of islands in the transition zone, forming the Great Kuril Ridge, stretched from the Siretoko Peninsula (Hokkaido Island) in the southwest to Lopatka Cape (Kamchatka Peninsula) in the northeast. Its length is about 1300 km. In plan, the ridge has the shape of an angle equal to 150 °, with a top in the area of \u200b\u200bthe strait. Boussol, facing the Pacific Ocean. It consists of 30 large, 20 small islands and rocks. total area of the islands of the Great Kuril ridge is 15.6 thousand km2. The archipelago is divided into three parts by the deep straits of Bussol and Krusenstern: the Southern, Middle and Northern Kuriles.
The southern Kurils include the large islands of the Great Kuril ridge: Kunashir, Iturup Urup, as well as the small islands of Black Brothers and Broughton. A significant area of \u200b\u200bthe large islands is hilly and terraced. Volcanic edifices with a height of 1200-1800 m rise above them (Tyatya, Mendeleeva, Atsonupuri, Berutarube, etc.) - Urup Island is somewhat distinguished by its massive basement. The Middle Kurils are the least represented large islands ridges: Ketoy, Ushishir, Rasshua, Matua, Raikoke. The largest of them is about. Simushir. The islands are the surface peaks of single volcanoes, reaching elevations up to 1500 m. The Northern Kuriles include the islands of Shi-ashkotan, Ekarma, Chirinkotan, Onekotan, Harim-kotan, Makanrushi, Antsiferova, Paramushir, Shumshu, Atlasova. They do not form a single chain. The largest of them (Paramushir and Shumshu islands) are located on the eastern edge of the Greater Kuril ridge. On about. Paramushir volcanoes exceed the mark of 1300 m (Karpinsky, Chikurach-ki), slightly below the Ebeko volcano (1183 m). The highest point of the island belongs to the top of the Fussa volcano - 1772 m.Of other islands, one can mention the Onekotan and Shiashkotan islands - groups of two volcanoes connected by low-lying jumpers, as well as the highest island of the Great Kuril ridge - Atlasova, which is the summit of the Alaid volcano and reaching 2339 m.
