Okhotsk
The edge of the Pacific Northwest. Located in Kuril Islands and between. The longest is 2460 kilometers from north to south, and the widest from east to west is 1480 kilometers, 10,000 square kilometers. The coastline is relatively straight, with a total length of 10,460 km. Sherekhov Bay, Oud Bay, TaiWan, Akademi Bay, etc. The sea is shallow in the north and deep in the south, with an average depth of 821 meters, a maximum depth of 3521 meters, and a water capacity of 136. 50,000 cubic kilometers.
Geomorphological geology
The Sea of Okhotsk was formed in the Quaternary Period (2.5 million to 10,000 years ago) and has experienced many glacial retreats. The slope of the seabed slopes downward from north to southwest. According to its geomorphological characteristics, it can be roughly divided into shelf area, land slope area and deep-water basin. The nearshore shelf area accounts for 40 per cent of the total area of the maritime area.
The central part of the seafloor is a land slope area, with a few subsubjected highlands, depressions and troughs.
There are two main deep-water basins: on the east side of Sakhalin Island is a wide Jelyujin Sea Basin, with rugged terrain; on the inner side of the Kuril Islands is the Thousand Island Basin, which is a deep-sea plain, which is the deepest part of the whole sea area. Seabed sediments, coarse gravel, fine gravel and sand in the inshore zone, sand in the shelf and island shelf areas, silty mud, silty clay and mud in deep waters, and tuff sediment in the Kuril Islands region, generally containing volcanic clastic material, have formed tuff sediment layers of various granular sizes in many places.
Earthquakes often occur on the seabed around the islands in the Sea of Okhotsk and form destructive waves (earthquake tsunamis). The continental shelf is vast (more than 42 per cent of the seafloor area) and is about 400 km wide and distributed in the north and west; the southern part of the Kuril Islands is the deep-sea basin (more than 9 per cent); the central part is a striped continental slope, alternating between submarine depressions and submarine plateaus (more than 48%). The current flows from the northeast through the central and Kuril Islands to the Pacific Ocean, where it merges with the currents from the Bering Sea to form the Kuril Islands Cold Current (pro-tide);
geographical location
The marginal seas of the Pacific Northwest are mostly surrounded by different topographical regions of Northeast Asia. The Sea of Okhotsk is bordered to the west by Russia's Siberian coast, from the Heilongjiang Estuary Bay in the south to the Penzhina estuary in the north. It is bounded by the Kamchatka Peninsula and the Kuril Islands to the east, Hokkaido, Japan, to the south, and Sakhalin Island in Russia to the southwest. The Sea of Okhotsk covers an area of 1,583,000 square kilometers, with an average depth of 777 meters, and the sea washes across the coasts of Japan and Russia.
Most of the continental coast is high rocky banks, interspersed with the mouths of regional rivers that flow into the sea. Such as Heilongjiang, Wudi River, Okhota River, Gizhiga River and Pinrena River. The seafloor slopes from north to south and southwest. The northern and northwestern parts are continental sheds up to 200 metres deep, while the rest (about 70 per cent of the total area) are continental slopes ranging from 200 m to 1500 m deep.
Terrain features
It is 2,460 kilometers long from north to south, 1,480 kilometers wide from east to west, has an area of about 1,528,000 square kilometers, and has an average water depth of 838 meters. There is a broad continental shelf in the north, and the water depth increases to the south. The water depth in the central part is 1000-1600 meters, and the deepest point in the east is 3658 meters. The coastline is relatively straight, with a total length of 10,460 km. The larger bays are Sherekhov Bay, Ude Bay, TaiWan Bay, Akademi Bay and so on. The sea is shallow north and deep in the south, with an average depth of 821 meters, and the north is shallow and deep in the south, with a maximum depth of 3521 meters (Thousand Island Basin). The water capacity is 1.365 million cubic kilometers. Salinity 32.8‰-33.8‰.
The Sea of Okhotsk is shallow to the north and deep to the south, the northern coast is the continental shelf area, the central is the continental slope area, and the southern sakhalin island (Sakhalin Island) is the east side and the inner kuril islands are two deep-water basins. The Kuril Islands at the edge of the basin are located in the crustal activity zone, with continental sheds up to 200 metres deep in the north and northwest, while the rest (about 70% of the total area) are continental slopes ranging from 200 m to 1500 m deep. The seafloor is frequently earthquakes and volcanic activity, with 30 active volcanoes and 70 extinct volcanoes. The seabed terrain slopes from north to south, with a wide continental shelf in the north and the famous Thousand Island Basin in the southeast, with a maximum depth of 3521 meters. The climate differences between the north and south of the Sea of Okhotsk are obvious. The north is at a high latitude, and extends into the Asian continent, with a subarctic continental climate, the winter is cold and long, the summer is warm and short, the annual precipitation is 400 mm-700 mm; the southern part is regulated by the ocean and belongs to the temperate oceanic climate, with an annual precipitation of more than 1000 mm. The average temperature in the north is -24°C in the north and -10°C in the south, while in August the average temperature in the north is 11°C and in the south is 17°C. Dry and cold northwesterly winds from the mainland in winter can not only stir up large waves on the sea surface, but also cause widespread cooling, causing most of the sea area to freeze. Ice generally begins in November in the north, with the ice age lasting until June, and the southern ice age mostly not exceeding 3 months. The sea area is icy or has ice floes, which is not conducive to navigation. Due to the confluence of cold and warm currents, thick fog forms in the sea area. There are many nutrients and salts in the seawater, which is conducive to the reproduction of marine life, producing Kamchatka crabs, salmon, herring, cod, flounder and so on. Important ports include Magadan and Okhotsk.
Coastal conditions
Most of the coast is steep and steep; the west coast of kamchatka, Sakhalin and the north shore of Hokkaido are low,craggy and have a relatively straight shoreline. The Great Bays are sherekhov Bay, Sakhalin Bay and Terpeniya Bay. Interspersed with the mouths of large regional rivers that flow into the sea. Such as the Heilongjiang, Uda, Okhota, Gizhiga and Pinrenna rivers.
Geological activity
The Hong Kong Observatory recorded a violent earthquake at 10:19 on 5 July 2008, with a central center about 380 kilometers west-northwest of Petropavlovsk, Russia, with a magnitude of 7.5 on the Richter scale. Preliminary analysis shows that the epicenter was located in the Sea of Okhotsk (53.9°N, 153.0°E) and no casualties or damage have been reported.
The China Earthquake Network officially determined that an earthquake of magnitude 8.2 occurred in the Sea of Okhotsk (54.9 °N, 153.3 °E) at 13:44 on May 24, 2013, with a depth of 600 kilometers.
The earthquake had two distinguishing features:
1. Huge earthquakes with a depth of more than 600 kilometers, which are very rare in the history of seismic observation;
2. Because the source is 600 kilometers deep (located in the mantle), the seismic wave propagates faster, the energy decay slows down, and the huge energy carried by the low-frequency component can be transmitted farther, which makes most of China have earthquakes.
Climatic characteristics
The Sea of Okhotsk has a temperate monsoon climate. Average temperatures: -20°C in the north and -7°C in the south in February, 12°C in the northeast and 18°C in the south in August. Surface water temperature: below 0 °C in winter and 8 °C-12 °C in summer. Surface salinity 25‰-35‰. The sea freezes from October to June, with the largest ice range in March, with an ice thickness of 1 meter. April-August is foggy, with heavy fog in the north and northwest. Winters are blizzards. Irregular daily tide, half-day tide, the maximum tide difference is 12.9 meters (Pinrenna Bay), the flow rate is about 7.5 knots. The current circulates in a counterclockwise direction at a velocity of 0.5 knots to 1.5 knots. Annual precipitation: 710 mm in the north, 1040 mm in the south. The average annual temperature varies with latitude, with minus 6°C in the north and 5.5°C in the south; at the same latitude, the east is 10°C higher than the west. Average monthly temperatures are lowest in January, with Scherikhov Bay and Uda Bay in the north at minus 24°C, while the Kuril Islands and Kamchatka are -10°C in the south, with a highest in August, with 11°C in the north and 17°C in the south.
Most of the Sea of Okhotsk freezes from October to June. The northern and western seas are influenced by the Asian continent and belong to the subarctic continental climate, with an average temperature of -20 °C to minus 24 °C in winter from January to February, 12 °C to 14 °C from July to August, an annual precipitation of 400 mm to 700 mm, and an ice freezing period of up to 7 months (November to June) with an ice thickness of 0.8 m-1 m. The southern and eastern parts are close to the Pacific Ocean, with an average temperature of -5°C to minus 7°C from January to February, and 12°C-18°C from July to August, with an annual water volume of more than 1000 mm. Due to the intersection of cold and warm currents in the sea area, there is thick fog during the melting ice period, and there is drift ice activity, which is not conducive to navigation. The salinity of the surface of the sea is 25‰-27‰ near Sakhalin Island, 32‰-33‰ near Kamchatka and 33‰ in the central part.
At the same time, the monsoon climate is very significant, with winter winds blowing from land to the sea, which is stronger and longer-lasting, and summer is more sea breeze. In autumn, there are many strong storms, with wind speeds of 20m/s-30m/s and waves as high as 8m-12m. In addition, the sea area is vulnerable to the Jin Wave (Earthquake and Tsunami), which is as high as 20 meters in an instant. With a wavelength of several kilometers and a propagation speed of 400 km/h to 800 km/h, it has caused great damage to the coastal areas, especially the Kuril Islands.
Ice is so severe that almost all of the sea area has sea ice to varying degrees. In the north, ice begins in November, with an ice period of up to 280 days and an ice thickness of 0.8 m-1 m; Kamchatka and the Kuril Islands are ice-less areas with an average of no more than 3 months per year. During the harsh winter season, sometimes the northwest wind blows ice floes towards the Kuril Islands, blocking certain straits. In summer, only sea ice remains near the Shantar Islands, and no ice in other sea areas.
Affected by the extreme climate of the Asian continent, the seas of northeast, north and west of Okhotsk have severe winters, and from October to April of the following year, the temperature in these areas is very low, and the sea waters have been frozen. The southern and southeastern seas are close to the Pacific Ocean and have a mild oceanic climate. The average temperature in the northern seas is minus 20 °C in February and 12 °C in August. The average temperature in the southern seas is -7°C in February and 18°C in August. At the end of October, the sea began to freeze, and by March it was the most severe.
Hydrological characteristics
The average depth of the Sea of Okhotsk is 821 meters, and the maximum depth is 3916 meters. The surface currents of the sea area generally flow from the northeast through the central and Kuril Islands to the Pacific Ocean, and merge with the currents from the Bering Sea to form a cyclonic circulation. The sea waters of the Sea of Okhotsk consist of water discharged from the mainland, rainwater, water flowing west from the Pacific Ocean through countless straits through the Kuril Islands, and water flowing north from the Sea of Japan through the Strait of La Perouse (also known as Zonggu). Affected by these currents, the water temperature in the eastern half of the sea is higher than in the western half, and the sea water generally flows in a counterclockwise direction. The waters that converge from the Pacific Ocean, especially between the eastern and central Kuril Islands, form turbulent rapids on several tributaries in the east and flow northwards, while in the west, waters flowing from the Siberian continent flow south in similar rapids.
The current is roughly cyclonic. After the warm water of the Pacific Ocean flows into the sea through the northern strait of the Kuril Islands, it is divided into two branches:
One headed northwest toward John Island, weakening in intensity. The other branches head north, to the northern coast and then turn west and southwest. Along the south, fresh water from various rivers (especially the runoff of the Heilongjiang River) is continuously incorporated, and then south along Sakhalin Island, which is a cold coastal current; and a small part flows from the north side of the La Piruze Strait (Zonggu Strait) to the Sea of Japan.
Warm water from the Sea of Japan flows into the Honkai area from the south side of the Lapiruz Strait (Munakata Strait) and flows east along the north shore of Hokkaido, known as the Soya Current. Flow rates can reach 50cm/s-90cm/s. Thus, a cyclonic total circulation is constituted. Flow rate, near shore is greater than the open sea. The flow rate in the open sea is generally 5cm/s-10cm/s, and the flow direction is relatively stable. The sea area is exchanged with the Pacific Ocean, mainly through the Straits of the Kuril Islands. For the archipelago as a whole, the upper layer flows north into and south out, while the deep layer flows mainly from the Pacific Ocean, which is different from the way the Strait of La Piruze (Soya Strait) enters and exits from the north and south with the Sea of Japan.
The main water masses are surface water, middle water and deep Pacific water. Surface water (0 m layer - 150 m layer or 200 m layer) is formed by vertical convection of seawater in winter, and the temperature and salinity characteristic values are -1.7C to 0.6C and 32.0C to 33.5C, respectively. The middle layer of water (200 m layer to 800 m layer) is formed by the mixed denaturation of the upper water flowing into the Pacific Ocean, and its temperature and salinity characteristic values are 0.1C-2C and 33.3C-33.8C, respectively. Deep Pacific water (800 m deep) is characterized by deep water inflow from the Pacific Ocean and is characterized by high temperatures (about 2.4C), low oxygen (<1 ml/l), and salinity of 34.3‰-34.4‰.
Tidal waves are introduced from the Pacific Ocean, and the tides are dominated by irregular full-day tides. Only the northern and northwestern coasts and the vicinity of the Shantar Islands are irregular half-day tides. The tide difference is small north and south. Near the Astronomical Cape of Pinnen Bay, the tidal range can reach 13 meters, the Shantar Islands can reach 7 meters, and the southern sea area is only 0.8 meters to 2.5 meters. The trend is divided into half-day tide and full-day tide. The flow rate varies from place to place, with only 5 cm/s to 10 cm/s in the open sea and 2 m/s to 4 m/s in the estuary of the strait and bay.
Straits and ports
The Sea of Okhotsk is the marginal sea of the Pacific Northwest. It is located between the Kuril Islands and the Asian mainland. It connects the Sea of Japan via the Strait of Munya (La Piruze) and the Pacific Ocean through the straits of the Kuril Islands. The Sea of Okhotsk has regular shipping links between the ports of the Russian Far East. The main ports along the coast are Magadan and Okhotsk in nagayevo bay. Korsakov on Sakhalin Islands and Severo-Kurilsk in the Kuril Islands in the North and Yuzhno-Kurilsk in the Kuril Islands are also important. Large chunks of ice floes hinder shipping in winter and fog obstruct traffic in summer. The Okhotsk Sea is bordered by kamchatka to the east, kuril islands to the southeast, Hokkaido island to the south, Siberia to the west and north, and Sakhalin Island to the southwest. The Sea of Okhotsk is connected to the Pacific Ocean via the Straits of the Kuril Islands and to the Sea of Japan in the Tatar Strait and the Strait of La Piruz (Mungu Strait). The most famous local landscape is the ice floes that appear on the surface of the sea in winter.
Biological condition
There are many nutrient salts in the seawater in this sea area, which is conducive to the reproduction of marine organisms. Phytoplankton are up to 20 g/m, mainly belonging to the phylum Diatoms, followed by dinoflagellates. Zooplankton biomass, in some areas up to 1 g/m -3 g/m. The total biomass of benthic organisms in the whole marine area is 200 million tons. Among the various fauna, molluscs are the most numerous, followed by echinoderms and polychaetes, and the more economically valuable are Kamchatka crabs, blue crabs and certain molluscs. There are about 300 species of fish, including salmon, herring, cod, flounder and other 30 species of fish, all of which have important economic value. There are also mammals such as sperm whales, sea lions and seals.
The waters of the continental shelf are rich in fishery resources, with many cold fish, mainly herring, salmon, trout and other fish, and there is the world's largest crab hunting farm near Kamchatka in the east. It is rich in salmon, trout, herring, cod and woolly scales. Coastal ports include Russia's Magadan, Okhotsk, Korsakov and Japan's Abashiri. There are many fur seals, beluga whales, sea donkeys, seals and other animals. Development was late, and it was only in 1713 that the voyage from Okhotsk to Kamchatka was launched. Important ports include Magadan, Okhotsk, Nikolayevsk (Temple Street), Korsakov, and Japan's Abashiri and Monobetsu, most of which are fishing ports. The waters around kamchatka are rich in fish and crabs. The warmer seasons of the Waters of Okhotsk are quite suitable for marine life. Marine plants include seaweed and seaweed, marine animals such as crayfish, mussels, crabs, sea urchins, polyps and a variety of fish, among which salmon, herring, green cod, flounder, cod, scaly fish and courgette fish, as well as crabs and brown shrimp are of high economic value. The Sea of Okhotsk is also home to mammals such as whales, seals, sea lions and fur seals.