Salinity and water temperature of the Sea of Okhotsk. Sea of Okhotsk. Bottom and coastline

Sea of Okhotsk located in the northwestern part Pacific Ocean off the coast of Asia and is separated from the ocean by a chain Kuril Islands and the Kamchatka Peninsula. From the south and west it is bounded by the coast of the island of Hokkaido, east coast Sakhalin Island and the coast of the Asian mainland. The sea is significantly elongated from southwest to northeast within a spherical trapezoid with coordinates 43°43"–62°42" N. sh. and 135°10"–164°45"E. d. Maximum length the water area in this direction is 2463 km, and the width reaches 1500 km. The surface area of the sea surface is 1603 thousand km2, the length of the coastline is 10460 km, and the total volume of sea water is 1316 thousand km3. In my own way geographic location it belongs to the marginal seas of the mixed continental-marginal type. The Sea of Okhotsk is connected to the Pacific Ocean by the numerous straits of the Kuril Islands, and to the Sea of Japan through the La Perouse Strait and through the Amur Estuary by the Nevelskoy and Tatar Straits. The average value of the sea depth is 821 m, and the largest is 3521 m (in the Kuril basin).

The main morphological zones in the bottom topography are: the shelf (the continental and insular shoals of Sakhalin Island), the continental slope, on which separate underwater elevations, depressions and islands stand out, and the deep-water basin. The shelf zone (0–200 m) is 180–250 km wide and occupies about 20% of the sea area. 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, occupies 8% of the sea area. Within the area of the continental slope, several elevations and depressions are distinguished, where the depths change dramatically (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 threshold separating the sea basin from the ocean.

The Amur Estuary, Nevelskoy in the north and Laperouse in the south straits connect the Sea of Okhotsk with the Sea of Japan, and the numerous Kuril Straits with the Pacific Ocean. The chain of the 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 Okhotsk with adjacent areas of the Sea of Japan and the Pacific Ocean provide the possibility of water exchange between the basins, which, in turn, have a significant impact on the distribution hydrological characteristics. The Nevelskoy and La Perouse straits are relatively narrow and shallow, which is the reason for the relatively weak water exchange with the Sea of Japan. The straits of the Kuril Islands, which stretch for about 1200 km, on the contrary, are deeper, and their total width is 500 km. The deepest are the Bussol (2318 m) and Krusenstern (1920 m) straits.

The northwestern coast of the Sea of Okhotsk is practically devoid of large bays, while the northern coast is significantly indented. The Tauiskaya Bay protrudes into it, the coasts of which are indented with bays and bays. The bay is separated from the Sea of Okhotsk by the Koni Peninsula.

The largest bay of the Sea of Okhotsk lies in its northeastern part, extending 315 km into the mainland. This is Shelikhov Bay with Gizhiginskaya and Penzhinskaya lips. The Gizhiginskaya and Penzhinskaya bays are separated by the elevated Taigonos Peninsula. In the southwestern part of 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.

The shores of the Kuril Islands are complex in outline and form small bays. From the Sea of Okhotsk side, the most large bays are located near the island of Iturup, which are deep-water and have a very intricately dissected bottom.

Quite a few mostly small rivers flow into the Sea of Okhotsk, 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 flow comes from the Amur River. Others comparatively major rivers- Penzhina, Okhota, Uda, Bolshaya (in Kamchatka) - bring much less to the sea fresh water. The flow comes mainly in spring and early summer. At this time, its greatest influence is felt mainly in the coastal zone, near the mouth areas of large rivers.

coast Sea of Okhotsk in different areas belong to different geomorphological types. For the most part, these are abrasion shores altered by the sea, and only on the Kamchatka Peninsula and Sakhalin Island are accumulative shores found. In general, the sea is surrounded by high and steep shores. In the north and northwest, rocky ledges descend directly to the sea. The coasts along the Sakhalin Bay are low. The southeastern coast of Sakhalin is low, and the northeastern coast is low. The shores of the Kuril Islands are very steep. The northeastern coast of Hokkaido is predominantly low-lying. The coast of the southern part of Western Kamchatka has the same character, but the shores of its northern part are somewhat elevated.

According to the features of the composition and distribution bottom sediments three main zones can be distinguished: the central one, which is composed mainly of diatomaceous silt, silty-argillaceous and partially clayey silts; the distribution zone of hemipelagic and pelagic clays in the western, eastern and northern parts of the Sea of Okhotsk; as well as the distribution zone of inequigranular sands, gravel sandstones and silts - in the northeast of the Sea of Okhotsk. Coarse clastic material, which is the result of ice rafting, is ubiquitous.

The Sea of Okhotsk is located in the monsoon zone. climate temperate latitudes. A significant part of the sea in the west deeply protrudes 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 Okhotsk is located to the west of it. Relatively high ridges Kamchatka impedes the penetration of warm Pacific air. Only in the southeast and south is the sea open to the Pacific Ocean and Sea of Japan where it receives a significant amount of heat. However, the influence of cooling factors is stronger than warming factors, so the Sea of Okhotsk is generally cold.

In the cold part of the year (from October to April), the Siberian anticyclone and the Aleutian low act on the sea. The influence of the latter extends mainly to the southeastern part of the sea. This distribution of large-scale baric systems causes strong persistent northwestern and northern winds often reaching storm strength. In winter, the wind speed is usually 10–11 m/s.

In the coldest month - January - average temperature air in the north-west of the sea is -20 ... -25 ° С, in central regions- –10...–15°С, and in the southeastern part of the sea - –5...–6°С.

In autumn and winter, cyclones are predominantly of continental origin. They bring with them an increase in wind, sometimes a decrease in air temperature, but the weather remains clear and dry, as continental air comes from the cooled mainland. In March - April, large-scale baric fields are restructured, the Siberian anticyclone is destroyed, and the Hawaiian maximum is strengthened. As a result, in the warm season (from May to October), the Sea of Okhotsk is under the influence of the Hawaiian maximum and the area of low pressure located above Eastern Siberia. At the same time, weak southeasterly winds prevail over the sea. Their speed usually does not exceed 6–7 m/s. Most often, these winds are observed in June and July, although stronger northwesterly and northerly winds are sometimes observed in these months. In general, the Pacific (summer) monsoon is weaker than the Asian (winter) monsoon, since the horizontal pressure gradients are smoothed out 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).

During the warm season over southern part seas quite often pass tropical cyclones - typhoons. They are associated with an increase in wind to a storm, which can last up to 5–8 days. The predominance of southeasterly winds in the spring-summer season leads to significant cloudiness, precipitation, and fog.
Monsoon winds and stronger winter cooling of the western part of the Sea of Okhotsk compared to the eastern part are important climatic features this sea.

Geographical position, large extent along the meridian, monsoonal change of winds and good connection seas with the Pacific Ocean through the Kuril Straits - the main natural factors, which most significantly affect the formation hydrological conditions Sea of Okhotsk.

The flow of surface Pacific waters into the Sea of Okhotsk occurs mainly through the northern straits, in particular through the First Kuril Strait.

In the upper layers of the southern part Kuril ridge the runoff of the Sea of Okhotsk waters predominates, and in the upper layers of the northern part of the ridge, Pacific waters enter. In the deep layers, the inflow of Pacific waters prevails.

The inflow of Pacific waters significantly affects the distribution of temperature, salinity, and the formation of the structure and general circulation of the waters of the Sea of Okhotsk.

The following water masses are distinguished in the Sea of Okhotsk:

– surface water mass with spring, summer and autumn modifications. It is a thin heated layer 15–30 m thick, which limits the upper stability maximum, which is mainly determined by temperature;
– the Sea of Okhotsk water mass is formed from surface water in winter and manifests itself in spring, summer and autumn as a cold intermediate layer lying between 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 descent of water 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 water mass is distributed 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 Okhotsk at the 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 represents the deep water of the northwestern part of the Pacific Ocean near the horizon of 2300 m. This water mass fills the basin from the horizon of 1350 m to the bottom and is characterized by a temperature of 1.85 ° C and a salinity of 34.7 change only slightly with depth.

Water temperature on the sea surface decreases from south to north. In winter, almost everywhere, the surface layers cool down to a freezing temperature of –1.5...–1.8°C. Only in the southeastern part of the sea does it stay around 0°C, and near the northern Kuril Straits, under the influence of Pacific waters, the water temperature reaches 1–2°C.
Spring warming at the beginning of the season mainly goes to the melting of ice, only towards the end of it does the water temperature begin to rise.

In summer, the distribution of water temperature on the sea surface is quite diverse. In August, the waters adjacent to the island of Hokkaido are warmest (up to 18–19°C). 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 Pyagin and near the Kruzenshtern Strait. In these areas, the water temperature is kept in the range of 6-7°C. 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 warm seasons.

In winter, in the northern and central regions of the sea, water cooling extends to horizons of 500–600 m. The water temperature is relatively uniform and varies from –1.5 ... 600 m, deeper it rises to 1–0°С, in the southern part of the sea and near the Kuril Straits, the water temperature drops from 2.5–3°С on the surface to 1–1.4°С at horizons of 300–400 m and further gradually rises to 1.9–2.4°C in the bottom layer.

In summer, surface waters are warmed up to a temperature of 10–12°C. In the subsurface layers, the water temperature is slightly lower than on the surface. A sharp decrease in temperature to –1...–1.2°С is observed between horizons of 50–75 m, deeper, to horizons of 150–200 m, the temperature quickly rises to 0.5–1°С, and then it rises more smoothly , and at the horizons of 200–250 m it is 1.5–2°С. Further, the temperature of the water almost does not change to the bottom. In the south and southeastern parts sea, along the Kuril Islands, the water temperature drops from 10–14°С on the surface to 3–8°С at a horizon of 25 m, then to 1.6–2.4°С at a horizon of 100 m and to 1.4–2 °C 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 Okhotsk, relatively little changes with seasons. Salinity increases in the eastern part, which is under the influence of Pacific waters, and decreases in the western part, which is desalinated by continental runoff. In the western part, 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 freshening, the salinity on the surface is 25‰ or less, and the thickness of the freshened layer is about 30–40 m.
Salinity increases with depth in the Sea of Okhotsk. At the horizons of 300–400 m in the western part of the sea, the salinity is 33.5‰, and in the eastern part it is about 33.8‰. At a horizon of 100 m, salinity is 34‰ and further towards the bottom it increases slightly, by only 0.5–0.6‰.

In some bays and straits, the salinity value, its stratification can differ significantly from the waters high seas 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. Some less density in a relatively warm Kuril region. In summer, the water density decreases, its lowest values are confined to the zones of influence of coastal runoff, and the highest values 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 horizons. IN summer time a noticeable density stratification of waters along the vertical is created, the density increases especially noticeably at the horizons of 25–50 m, which is associated with the heating of waters in open areas and desalination near the coast.

Intense ice formation over most of the sea excites an enhanced thermohaline winter vertical circulation. At depths up to 250–300 m, it propagates to the bottom, and below it is prevented by the maximum stability that exists here. In areas with a rugged bottom topography, the spread of density mixing into the lower horizons is facilitated by the sliding of water along the slopes.

Under the influence of winds and water inflow through the Kuril Straits, character traits systems of non-periodic currents Sea of Okhotsk. The main one is the cyclonic system of currents, covering almost the entire sea. It is due to the predominance of cyclonic circulation of the atmosphere over the sea and the adjacent part of the Pacific Ocean. In addition, stable anticyclonic gyres can be traced in the sea.
Strong currents bypass the sea along the coastline counterclockwise: the warm Kamchatka Current, the stable East Sakhalin Current and the fairly strong Soya Current.
And finally, one more feature of the water circulation in the Sea of Okhotsk is two-way stable currents in most of the Kuril straits.

Currents on the surface of the Sea of Okhotsk are most intense near the western coast of Kamchatka (11–20 cm/s), in the Sakhalin Bay (30–45 cm/s), in the region of the Kuril Straits (15–40 cm/s), over the Kuril Basin (11 –20 cm/s) and during the Soya (up to 50–90 cm/s).

In the Sea of Okhotsk are well expressed different kinds periodical tidal currents: semidiurnal, diurnal mixed with a predominance of semidiurnal or diurnal components. The velocities of tidal currents range from a few centimeters to 4 m/s. Away 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 Okhotsk are very significant and have a significant impact on its hydrological regime, especially in the coastal zone.
In addition to tidal fluctuations, surge fluctuations in the level are also well developed here. They occur mainly during the passage of deep cyclones over the sea. Surge rises in the level reach 1.5–2 m. The largest surges are noted on the coast of Kamchatka and in the Gulf of Patience.

Significant size and great depths Sea of Okhotsk, frequent and strong winds over it cause the development of large waves here. The sea is especially stormy in autumn, and in some areas even in winter. These seasons account for 55–70% of storm waves, including those with wave heights of 4–6 m, and greatest heights waves 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 ordinary years, the southern border of a 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, due 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 Okhotsk lasts for 6–7 months. floating ice more than 75% of the sea surface is covered. Close-packed ice in 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 Okhotsk is carried into the ocean, where it breaks up and melts almost immediately.

Forecast resources hydrocarbons Sea of Okhotsk is estimated at 6.56 billion tons of oil equivalent, explored reserves - over 4 billion tons. The largest deposits on the shelves (along the coast of Sakhalin Island, the Kamchatka Peninsula, Magadan region). The deposits of Sakhalin Island are the most studied. Exploration work on the shelf of the island began in the 70s. In the 20th century, by the end of the 1990s, 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 North-Eastern Sakhalin. The total gas reserves on the Sakhalin shelf are estimated at 3.5 trillion m3.

Vegetation and animal world are of great variety. 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, sockeye - a source of red caviar. Intensive fishing is carried out for herring, pollock, flounder, cod, navaga, capelin, etc. Whales, seals, sea lions, fur seals live in the sea. The fishing of mollusks and sea urchins is gaining more and more interest. Various algae are ubiquitous in the littoral.
Due to the poor development of the adjacent territories, maritime transport has become of primary importance. Important sea routes lead to Korsakov on Sakhalin Island, Magadan, Okhotsk and other settlements.

the greatest anthropogenic load the areas of the Tauiskaya Bay in the northern part of the sea and the shelf areas of Sakhalin Island are affected. IN northern part The sea annually receives about 23 tons of oil products, with 70–80% coming from river runoff. Pollutants enter the Tauyskaya Bay from onshore industrial and municipal facilities, and the wastewater from Magadan enters the coastal zone practically without treatment.

The shelf zone of Sakhalin Island is polluted by coal, oil and gas production enterprises, pulp and paper mills, fishing and processing vessels and enterprises, and sewage from municipal facilities. Annual receipt of oil products in southwestern part seas are estimated at about 1.1 thousand tons, with 75–85% of river runoff.
Petroleum hydrocarbons enter the Sakhalin Bay mainly with the runoff of the Amur River; therefore, their maximum concentrations, as a rule, are noted in the central and western parts bay along the axis of incoming Amur waters.

The eastern part of the sea - the shelf of the Kamchatka Peninsula - is polluted by river runoff, with which the main part of petroleum hydrocarbons 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 wastewater discharged into the coastal zone of the sea.

The northern part of the sea - Shelikhov Bay, Tauyskaya and Penzhinskaya bays - is the most polluted area of the sea with an average content of petroleum carbons in 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 low average annual temperatures water and, consequently, the low capacity of the ecosystem for self-purification. The highest level of pollution in the northern part of the Sea of Okhotsk was noted in the period from 1989 to 1991.

The southern part of the sea - the La Perouse Strait and the Aniva Bay - are subjected to intense oil pollution in the spring-summer period by commercial and fishing fleets. On average, the content of petroleum hydrocarbons in the La Perouse Strait does not exceed the limit of permissible concentration. Aniva Bay is slightly more polluted. The highest level of pollution in this area was noted near the port of Korsakov, once again confirming that the port is a source of intense pollution of the marine environment.
Pollution coastal zone 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 80s of the last century did not exceed the maximum permissible concentration.

Salinity at the sea surface

The salinity of sea waters is determined by many processes. These include the volume of fresh precipitation, the amount of runoff of the Amur and other rivers, the amount of evaporation, the amount of input into the sea warm waters increased salinity, ice formation and melting, tidal mixing and upwelling. The uneven change in these components over a large area of the sea and in different seasons determines significant changes in salinity, both spatial and temporal.

During the year, the salinity of the surface waters of the sea varies widely from less than 20‰ to 33.2‰. Salt waters with values of more than 32.5‰ are located mainly where warm currents pass: along about. Hokkaido, the Kuril Islands and a strip expanding to the northwest from the 4th Kuril Strait. Desalinated waters with relatively low values (less than 32.0‰) are mainly observed where the river flow is significant: in the Sakhalin Bay, near the Shantar Islands, along the coast of the island. Sakhalin and the continent.

In winter, the salinity of surface waters is maximum. It increases everywhere with the influx of salt during the formation of ice and a decrease in river flow in winter. In February, the salinity of ice-free surface waters is 32.6-33.3‰.

In spring, when the ice melts and the river runoff increases sharply, the salinity of surface waters in coastal zones drops to 30-31‰ (near the northeastern shores of Sakhalin Island, to 20-25‰). In the open sea, it is 32.5-33.0‰; Hokkaido and the Kuril Islands - 33.0-33.5‰.

In summer, the salinity of surface waters is minimal. Sakhalin - up to 32‰, and in the open sea - up to 32.4‰. Only a strip of warm and salty (more than 32.8‰) water, stretching from the 4th Kuril Strait, and the coastal area along the island. Hokkaido is characterized by high (up to 33.2‰) salinity.

In November-December, salinity in the entire area of the sea increases again with the formation of ice.

In the warm season, even in average salinity fields near Sakhalin, Kamchatka, in the Taui Bay), zones of increased horizontal gradients are distinguished - salinity fronts. Coastal salinity fronts pass approximately in the same place as thermal fronts. Only in the central part of the sea are the thermal and salinity fronts completely different. If the thermal fronts limiting the belt of warm water narrowing from all the Kuril Islands to the north are directed to the northeast, then the salinity fronts limiting the belt expanding to the north salt water, are directed from the 4th Kuril Strait to the northwest. The salinity in this belt with values over 32.9‰ is significantly (by 0.2-0.4‰) higher than the salinity of the surrounding waters.

With depth, salinity increases almost continuously throughout the entire sea and in all seasons.

Salinity in deep layers

At the 50 m horizon, spatial changes in salinity decrease to the range of 32–33.5‰, while seasonal changes do not exceed 0.5–1.5‰. At the end and immediately after winter (in April-May), the highest water salinity on this horizon was noted near the northwestern coast of Kamchatka. But in summer (July-August), when the northwestern part of the sea is free of ice, here the salinity of the waters at the 50 m horizon is comparable (up to 33.3‰) with the salinity (up to 33.4‰) of the waters of those areas where warm waters penetrate (p- s Kamchatka and Hokkaido).

In September and October, the salinity of the waters at this horizon decreases everywhere. And only off the coast of. Hokkaido it is increasing. In December, salinity increases everywhere and the area of low salinity waters decreases. The highest values, as well as on the sea surface, are confined to areas of penetration of warm waters. At the same time, high (more than 33.1‰) values are typical not only for the region of the 4th Kuril Strait and coastal waters of the island. Hokkaido, but also for the area around about. Ions.

At a horizon of 100 m, intra-annual changes in salinity decrease even more (to 0.5-1.0‰), while highest values it is characteristic of the Kuril Straits. At a horizon of 200 m, spatial changes in salinity decrease to 0.2–0.3‰, and temporal changes to 0.1–0.15‰.

At the 500 m horizon, the average salinity increases to 33.6–33.8‰. At the same time, salinity increases in the direction from the southeast to the northwest. At the 1000 m horizon, salinity increases to 34.2–34.4‰. Salinity also increases in the direction from the southeast to the northwest. This horizon is special. In the southern part of the sea, on this horizon, the main halocline is located (in the central part of the sea, it is several hundred meters higher). The salinity growth rate up to this horizon is 0.1‰ per 100 m, and below this horizon it sharply decreases to 0.02‰ deeper than 1200 m.

The horizontal distribution of salinity in April, June, August and November at standard horizons is presented in the appendix.

1. Sea of Okhotsk.

2. The sea enters the Pacific basin.

3. Located in the northwestern part of the Pacific Ocean, separated from the ocean by the Kamchatka Peninsula, the Kuril Islands and the island of Hokkaido.

4. Located between 43° and 62° parallel north latitude.

5. Position of the sea between 135° and 165° meridians east longitude.

6. The length of the sea in directions in degrees and kilometers:

The extent of the sea from south to north is 19° degrees, i.e. approximately 2100 km;

The length of the sea from east to west is 20° degrees, 1575 km.

The length in km was calculated based on the length between parallels and meridians on a map with a scale of 1:35,000,000.

7. Washes the shores of Russia and Japan: the Kamchatka Peninsula, the Kuril Islands, about. Hokkaido, oh Sakhalin, Shantar Islands.

8. neighboring seas: the La Perouse Strait and the Tatar Strait (through the Amur Estuary) connect the Sea of Okhotsk with the Sea of Japan.

Neighbor Ocean: The First Kuril Strait and a number of straits in the chain of the Kuril Islands, such as the Fourth Kuril Strait, the Krusenstern Strait, the Bussol Strait and the Friza Strait, connect the Sea of Okhotsk to the Pacific Ocean.

9. View of the sea: marginal sea.

10. In winter, the water temperature at the sea surface ranges from -1.8° to 2.0° C, in summer surface waters warm up to 10° C and above.

11. The maximum depth of the sea: 3521 m (in the Kuril basin), in some sources there is a depth of 3916 m, but I did not find this figure on the map, so you can operate with it if it is in your textbook.

Fig. 12. Distribution of depths The shelf zone (0–200 m) occupies about 20% of the sea area, the continental slope (200–2000 m), on which separate underwater heights, depressions and islands are distinguished by a sharp change in depths, and the deep-sea basin occupies about 65%, and the deepest basin (more than 2500 m), located in the southern part of the sea - 8% of the sea area.

13. Distribution of water salinity: according to the map of the average annual salinity of the surface waters of the World Ocean, in the northern and eastern parts of the sea, the salinity of surface waters is up to 32 ppm, and in the central, western and southern parts of the sea, the salinity of surface waters is up to 33 ppm.

14. The Sea of Okhotsk is located in a temperate climate zone, while its East End(in the region of the Kuril Islands) is located in maritime area temperate climate, and the rest in the temperate monsoon region.

15. Features of the structure of the bottom:

The bottom is a wide range of different underwater elevations, depressions and trenches. The northern part of the sea is located on the continental shelf. In the western part of the sea there is a sandbank of Sakhalin, located near the island. In the east of the sea is the continental shelf of Kamchatka. As indicated in paragraph 12, most of the water expanses are located on the continental slope. South edge sea is the deepest zone, this part of the sea is a bed that is located along the Kuril Islands. The southwestern part of the sea is characterized deep depressions and slopes. In the central zone of the sea there are two elevations: the Academy of Sciences and the Institute of Oceanology, they divide the marine underwater space into 3 basins: the northeastern TINRO basin (small depth of about 850 m, flat terrain), which is located west of Kamchatka. The second basin is the Deryugin depression, located east of Sakhalin, the water depth here reaches 1700 m, the bottom is a plain, the edges of which are somewhat elevated. The third basin - the Kuril - is the deepest (about 3300 m) of these three.

16. Features of the organic world.

Flora and fauna, on the one hand, are distinguished by great diversity, and, on the other hand, by the uneven distribution of this diversity. If in the southern, warmer part, the number of fish species is about 300, then in the northern, colder part, the number of species is more than two times less, only about 123 species. Nevertheless, 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, sockeye salmon as a source of red caviar. There is also intensive fishing for herring, pollock, flounder, cod, navaga, capelin, etc. Whales, seals, sea lions, fur seals live in the sea. A huge amount of green, brown and red medicinal algae stands out from the flora.

Separated by conditional boundaries. The Sea of Okhotsk is a fairly large and deep sea in our country. Its area is about 1603 thousand km2, the volume of water is 1318 thousand km3. Average depth this sea is 821 m, maximum depth- 3916 m. According to its features, this sea is a marginal sea of a mixed continental-marginal type.

There are few islands in the waters of the Sea of Okhotsk, among which the largest is. The Kuril ridge consists of 30 different in size. Their location is seismically active. There are more than 30 active and 70 extinct ones here. Seismic activity zones can be located both on islands and under water. If the epicenter is under water, then huge ones rise.

The coastline of the Sea of Okhotsk, with a considerable length, is quite equal. There are many large bays along the coastline: Aniva, Patience, Sakhalin, Academies, Tugursky, Ayan and Shelikhov. There are also several lips: Tauiskaya, Gizhiginskaya and Penzhinskaya.

Sea of Okhotsk

The bottom is a wide range of different underwater elevations,. The northern part of the sea is located on the continental shelf, which is a continuation of the land. In the western zone of the sea there is a shoal of Sakhalin, located near the island. In the east of the Sea of Okhotsk is Kamchatka. Only a small part is located in the shelf zone. A significant part of the water expanses is located on the continental slope. The depth of the sea here varies from 200 m to 1500 m.

The southern edge of the sea is the deepest zone, the maximum depth here is more than 2500 m. This part of the sea is a kind of bed, which is located along the Kuril Islands. The southwestern part of the sea is characterized by deep depressions and slopes, which is not characteristic of the northeastern part.

In the central zone of the sea there are two hills: the Academy of Sciences of the USSR and the Institute of Oceanology. These elevations divide the sea underwater space into 3 basins. The first basin is the northeastern TINRO basin, which is located to the west of Kamchatka. This depression is distinguished by small depths, about 850 m. The bottom has. The second basin is the Deryugin depression, located to the east of Sakhalin, the water depth here reaches 1700 m. The bottom is a plain, the edges of which are somewhat elevated. The third basin is the Kuril. It is the deepest (about 3300 m). is a plain that extends 120 miles in the western part, and 600 miles in the northeast.

The Sea of Okhotsk is influenced by the monsoon climate. The main source of cold air is located in the west. This is due to the fact that the western part of the sea is strongly cut into the mainland and is located not far from the Asian cold pole. Relatively high from the east mountain ranges Kamchatka impede the advancement of warm Pacific. The largest number heat comes from the waters of the Pacific Ocean and the Sea of Japan through the southern and southeastern borders. But the influence of cold air masses dominates over warm air masses, therefore, in general, the Sea of Okhotsk is quite severe. The Sea of Okhotsk is the coldest in comparison with the Sea of Japan.

Sea of Okhotsk

During the cold period (which lasts from October to April), the Siberian and Aleutian lows have a significant effect on the sea. As a result, winds from the northern and northwestern directions prevail in the Sea of Okhotsk. The power of these winds often reaches storm strength. Especially strong winds are observed in January and February. Their average speed is about 10 - 11 m / s.

In winter, the cold Asian monsoon contributes to a strong decrease in the northern and northwestern parts of the sea. In January, when the temperature reaches its minimum limit, on average the air cools down to -20-25°C in the northwestern part of the sea, to -10-15°C in the central part and to -5-6°C in the southeastern part. In the last zone, the influence of warm Pacific air is felt.

In autumn and winter, the sea is under the influence of continental. This leads to increased wind, and in some cases to cooling. In general, it can be described as clear with reduced. These climatic features are influenced by cold Asian air. In April-May, the Siberian anticyclone ceases to operate, and the influence of the Honolulu maximum increases. In this regard, during the warm period, small southeast winds are observed, the speed of which rarely exceeds 6–7 m/s.

In summer, there are different temperatures depending on. In August, the highest temperature is recorded in the southern part of the sea, it is +18°C. In the central part of the sea, the temperature drops to 12-14°C. The northeast has the coldest summer, the average temperature does not exceed 10-10.5°C. During this period, the southern part of the sea is subject to numerous oceanic cyclones, due to which the wind strength increases, and storms rage for 5-8 days.

Sea of Okhotsk

A large number of rivers carry their waters to the Sea of Okhotsk, but they are all mostly small. In this regard, it is small, it is about 600 km 3 during the year. , Penzhina, Okhota, Bolshaya - the largest flowing into the Sea of \u200b\u200bOkhotsk. Fresh waters have little effect on the sea. The waters of the Sea of Japan and the Pacific Ocean are of great importance for the Sea of Okhotsk.

The Sea of Okhotsk is 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 bounded by the coast of Hokkaido, the eastern coast of Sakhalin Island and the coast of the Asian mainland. The sea is significantly elongated from southwest to northeast within a spherical trapezoid with coordinates 43°43'–62°42' N. sh. and 135°10’–164°45′ E. e. The greatest length of the water area in this direction is 2463 km, and the width reaches 1500 km. The surface area of the sea surface is 1603 thousand km2, the length of the coastline is 10460 km, and the total volume of sea water is 1316 thousand km3. According to its geographical position, it belongs to the marginal seas of the mixed continental-marginal type. The Sea of Okhotsk is connected to the Pacific Ocean by the numerous straits of the Kuril Islands, and to the Sea of Japan through the La Perouse Strait and through the Amur Estuary by the Nevelskoy and Tatar Straits. The average value of the sea depth is 821 m, and the largest is 3521 m (in the Kuril basin).

The Amur Estuary, Nevelskoy in the north and Laperouse in the south straits connect the Sea of Okhotsk with the Sea of Japan, and the numerous Kuril Straits with the Pacific Ocean. The chain of the 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 Okhotsk with the adjacent areas of the Sea of Japan and the Pacific Ocean provide the possibility of water exchange between the basins, which, in turn, have a significant impact on the distribution of hydrological characteristics. The Nevelskoy and La Perouse straits are relatively narrow and shallow, which is the reason for the relatively weak water exchange with the Sea of Japan. The straits of the Kuril Islands, which stretch for about 1200 km, on the contrary, are deeper, and their total width is 500 km. The deepest are the Bussol (2318 m) and Krusenstern (1920 m) straits.

The shores of the Kuril Islands are complex in outline and form small bays. On the Sea of Okhotsk side, the largest bays are located near Iturup Island, which are deep-water and have a very intricately dissected bottom.

Quite a few mostly small rivers flow into the Sea of Okhotsk, 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 flow comes from the Amur River. Other relatively large rivers - Penzhina, Okhota, Uda, Bolshaya (in Kamchatka) - bring much less fresh water to the sea. The flow comes mainly in spring and early summer. At this time, its greatest influence is felt mainly in the coastal zone, near the mouth areas of large rivers.

The shores of the Sea of Okhotsk in different regions belong to different geomorphological types. For the most part, these are abrasion shores altered by the sea, and only on the Kamchatka Peninsula and Sakhalin Island are accumulative shores found. In general, the sea is surrounded by high and steep shores. In the north and northwest, rocky ledges descend directly to the sea. The coasts along the Sakhalin Bay are low. The southeastern coast of Sakhalin is low, and the northeastern coast is low. The shores of the Kuril Islands are very steep. The northeastern coast of Hokkaido is predominantly low-lying. The coast of the southern part of Western Kamchatka has the same character, but the shores of its northern part are somewhat elevated.

According to the features of the composition and distribution of bottom sediments, three main zones can be distinguished: the central zone, which is composed mainly of diatomaceous silt, silty-argillaceous and partially clayey oozes; the distribution zone of hemipelagic and pelagic clays in the western, eastern and northern parts of the Sea of Okhotsk; as well as the distribution zone of inequigranular sands, gravel sandstones and silts - in the northeast of the Sea of Okhotsk. Coarse clastic material, which is the result of ice rafting, is ubiquitous.

The Sea of Okhotsk is located in the monsoon climate zone of temperate latitudes. A significant part of the sea in the west deeply protrudes 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 Okhotsk is located to the west of it. The relatively high ridges of Kamchatka make it difficult for warm Pacific air to penetrate. Only in the southeast and south is the sea open to the Pacific Ocean and the Sea of Japan, from where a significant amount of heat enters it. However, the influence of cooling factors is stronger than warming factors, so the Sea of Okhotsk is generally cold.

In the cold part of the year (from October to April), the Siberian anticyclone and the Aleutian low act on the sea. The influence of the latter extends mainly to the southeastern part of the sea. This distribution of large-scale baric systems causes strong persistent northwesterly and northerly winds, often reaching storm strength. In winter, the wind speed is usually 10–11 m/s.

In the coldest month - January - the average air temperature in the north-west of the sea is -20 ... -25 ° С, in the central regions - -10 ... -15 ° С, and in the south-eastern part of the sea - -5 ... -6 ° WITH.

In autumn and winter, cyclones are predominantly of continental origin. They bring with them an increase in wind, sometimes a decrease in air temperature, but the weather remains clear and dry, as continental air comes from the cooled mainland. In March - April, large-scale baric fields are restructured, the Siberian anticyclone is destroyed, and the Hawaiian maximum is strengthened. As a result, during the warm season (from May to October), the Sea of Okhotsk is under the influence of the Hawaiian maximum and the area of low pressure located over Eastern Siberia. At the same time, weak southeasterly winds prevail over the sea. Their speed usually does not exceed 6–7 m/s. Most often, these winds are observed in June and July, although stronger northwesterly and northerly winds are sometimes observed in these months. In general, the Pacific (summer) monsoon is weaker than the Asian (winter) monsoon, since the horizontal pressure gradients are smoothed out 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 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 predominance of southeasterly winds in the spring-summer season leads to significant cloudiness, precipitation, and fog.

Monsoon winds and stronger winter cooling of the western part of the Sea of Okhotsk compared to the eastern part are important climatic features of this sea.

Geographical position, large length along the meridian, monsoonal change of winds and good connection of the sea with 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 Okhotsk.

The flow of surface Pacific waters into the Sea of Okhotsk occurs mainly through the northern straits, in particular through the First Kuril Strait.

In the upper layers of the southern part of the Kuril ridge, the runoff of the Sea of Okhotsk waters predominates, and in the upper layers of the northern part of the ridge, Pacific waters enter. In the deep layers, the inflow of Pacific waters prevails.

The inflow of Pacific waters significantly affects the distribution of temperature, salinity, and the formation of the structure and general circulation of the waters of the Sea of Okhotsk.

The following water masses are distinguished in the Sea of Okhotsk:

surface water mass with spring, summer and autumn modifications. It is a thin heated layer 15–30 m thick, which limits the upper stability maximum, which is mainly determined by temperature;
the Sea of Okhotsk water mass is formed from surface water in winter and manifests itself in spring, summer, and autumn as a cold intermediate layer lying between 40–150 m horizons. This water mass is characterized by fairly uniform salinity (31–32‰) and different temperatures;
the intermediate water mass is formed mainly due to the descent of water 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 water mass is distributed 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 Okhotsk at horizons below 800–1000 m. This water mass is located at horizons of 600–1350 m, has a temperature of 2.3 ° C and a salinity of 34.3‰ .

The water temperature on the sea surface decreases from south to north. In winter, almost everywhere, the surface layers cool down to a freezing temperature of –1.5…–1.8°C. Only in the southeastern part of the sea does it stay around 0°C, and near the northern Kuril Straits, under the influence of Pacific waters, the water temperature reaches 1–2°C.
Spring warming at the beginning of the season mainly goes to the melting of ice, only towards the end of it does the water temperature begin to rise.

In winter, in the northern and central regions of the sea, water cooling extends to horizons of 500-600 m. The water temperature is relatively uniform and varies from -1.5 ... -1.7 ° С on the surface to -0.25 ° С at horizons of 500-600 m , deeper it rises to 1–0°C, in the southern part of the sea and near the Kuril Straits, the water temperature drops from 2.5–3°C on the surface to 1–1.4°C at 300–400 m horizons and then gradually rises up to 1.9–2.4°С in the bottom layer.

In summer, surface waters are warmed up to a temperature of 10–12°C. In the subsurface layers, the water temperature is slightly lower than on the surface. A sharp drop in temperature to –1…–1.2°C is observed between horizons of 50–75 m, deeper, to horizons of 150–200 m, the temperature quickly rises to 0.5–1°C, and then it rises more smoothly, and at the horizons of 200–250 m it is 1.5–2°С. Further, the temperature of the water almost does not change to the bottom. In the southern and southeastern parts of the sea, along the Kuril Islands, the water temperature drops from 10–14°С at the surface to 3–8°С at the 25 m horizon, then to 1.6–2.4°С at the 100 m horizon. and up to 1.4–2°C near 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 Okhotsk varies relatively little from season to season. Salinity increases in the eastern part, which is under the influence of Pacific waters, and decreases in the western part, which is desalinated by continental runoff. In the western part, 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 freshening, the salinity on the surface is 25‰ or less, and the thickness of the freshened layer is about 30–40 m.

Salinity increases with depth in the Sea of Okhotsk. At the horizons of 300–400 m in the western part of the sea, the salinity is 33.5‰, and in the eastern part it is about 33.8‰. At a horizon of 100 m, salinity is 34‰ and further towards the bottom it increases slightly, by only 0.5–0.6‰.

In individual bays and straits, 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 less in the relatively warm Kuril region. In summer, the water density decreases, its lowest values are confined to the zones of influence of coastal runoff, and the highest values 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 horizons. In summer, a noticeable density stratification of waters along the vertical is created, the density increases especially noticeably at horizons of 25–50 m, which is associated with the heating of waters in open areas and desalination near the coast.

Under the influence of winds and water inflow through the Kuril Straits, characteristic features of the system of non-periodic currents of the Sea of Okhotsk are formed. The main one is the cyclonic system of currents, covering almost the entire sea. It is due to the predominance of cyclonic circulation of the atmosphere over the sea and the adjacent part of the Pacific Ocean. In addition, stable anticyclonic gyres can be traced in the sea.

Strong currents bypass the sea along the coastline counterclockwise: the warm Kamchatka Current, the stable East Sakhalin Current and the fairly strong Soya Current.

And finally, one more feature of the water circulation in the Sea of Okhotsk is two-way stable currents in most of the Kuril straits.

In the Sea of Okhotsk, various types of periodic tidal currents are well expressed: semidiurnal, diurnal, and mixed with a predominance of semidiurnal or diurnal components. The velocities of tidal currents range from a few centimeters to 4 m/s. Away 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.

The significant size and great depths of the Sea of Okhotsk, frequent and strong winds over it determine the development of large waves here. The sea is especially stormy in autumn, and in some areas even in winter. These seasons account for 55–70% of storm waves, including those with wave heights of 4–6 m, and the highest wave heights reach 10–11 m. The most 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 ordinary years, the southern boundary of the relatively stable ice cover curves northward and runs from the La Perouse Strait to Cape Lopatka.
The extreme southern part of the sea never freezes. However, due 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 Okhotsk lasts for 6–7 months. Floating ice covers more than 75% of the sea surface. Close-packed ice in 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 Okhotsk is carried into the ocean, where it breaks up and melts almost immediately.

The predicted hydrocarbon resources of the Sea of Okhotsk are estimated at 6.56 billion tons of oil equivalent, the proven reserves are over 4 billion tons. The largest deposits are on the shelves (along the coast of Sakhalin Island, the Kamchatka Peninsula, the Khabarovsk Territory and the Magadan Region). The deposits of Sakhalin Island are the most studied. Exploration work on the shelf of the island began in the 70s. In the 20th century, by the end of the 1990s, 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 North-Eastern Sakhalin. The total gas reserves on the Sakhalin shelf are estimated at 3.5 trillion m3.

The flora 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, sockeye - a source of red caviar. Intensive fishing is carried out for herring, pollock, flounder, cod, navaga, capelin, etc. Whales, seals, sea lions, fur seals live in the sea. The fishing of mollusks and sea urchins is gaining more and more interest. Various algae are ubiquitous in the littoral.
Due to the poor development of the adjacent territories, maritime transport has become of primary importance. Important sea routes lead to Korsakov on Sakhalin Island, Magadan, Okhotsk and other settlements.

The areas of the Tauiskaya Bay in the northern part of the sea and the shelf areas of Sakhalin Island are subjected to the greatest anthropogenic load. About 23 tons of oil products enter the northern part of the sea annually, 70–80% of which comes from river runoff. Pollutants enter the Tauyskaya Bay from onshore industrial and municipal facilities, and the wastewater from Magadan enters the coastal zone practically without treatment.

Petroleum hydrocarbons enter the Sakhalin Bay mainly with the runoff of the Amur River, therefore, their maximum concentrations, as a rule, are noted in the central and western parts of the bay along the axis of the incoming Amur waters.

The northern part of the sea - Shelikhov Bay, Tauyskaya and Penzhinskaya bays - is the most polluted area of the sea with an average content of petroleum carbons in 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, the low ability of the ecosystem to self-purify. The highest level of pollution in the northern part of the Sea of Okhotsk was noted in the period from 1989 to 1991.

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, it did not exceed the maximum permissible concentration.

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Salinity and water temperature of the Sea of ​​Okhotsk. Sea of ​​Okhotsk. Bottom and coastline

Salinity at the sea surface

Salinity in deep layers

Salinity and water temperature of the Sea of Okhotsk. Sea of Okhotsk. Bottom and coastline