East Siberian Sea
The E.S.S. is one of the mainland marginal seas of the Arctic Ocean. Its area is 913 thousand km2, shelf area 889.1 thousand km2, volume 49 thousand km3, average depth 54 to 58 m, and maximum depth 915 m. The sea is shallow because it lies fully on a continental shelf, 72 % are less than 50 m deep.
Relatively large bays are the Chaun Bay, the Kolyma Bay, and the Omulyakh and Khromskaya Bays. There are not many large islands: Medvezhyi, Ayon, and Shalaurov Island. In the coastal area of the E.S.S., small islands are mostly clustered. There are such groups of islands close to the Kolyma mouth from the north side, at the entrance to the Chaun Bay and the Aachim Bay.
The shoreline presents quite large curves, sometimes continuing into the land, sometimes protruding into the sea, but there are areas with a straight shoreline. All the shores lie within the territory of the Russian Federation. Small curves usually associate with the mouths of small rivers. The landscapes of the western coast of the E.S.S. differ drastically from those of the eastern coast. In the area from the New Siberian Islands up to the mouth of the Kolyma River, the shores are very low and drab. Here waterlogged tundra comes close to the sea. Further to the east from the shores of the Kolyma, after Cape Bolshoy Baranov, the coast gets hilly. Hills come close to the water from the Kolyma mouth to Ayon Island and sometimes cliff sharply. The Chaun Bay is fringed with low but steep straightened shores. The coast that is different in relief and formation belongs to different morphological types of shores.
The submerged relief of the shelf, forming the sea bottom, is generally speaking a plain, which is slightly sloping from the southwest to the northeast. The sea bottom does not have any significant depressions or uplands. Predominant depth is 20–25 m. To the northeast of the Indigirka mouth and the Kolyma mouth, there are shallow trenches on the sea bottom. They are believed to be the remnants of ancient river valleys which were flooded by the sea. The area of small depths in the western part of the sea presents the so-called Novosibirskaya Shoal. The deepest parts of the sea are in its northeastern part. It gets noticeably deeper within the depths from 100 to 200 m.
The E.S.S. situated in the high altitudes lies in the zone of the Atlantic and the Pacific Oceans’ influence. Rare as they are, the western part of the sea sees cyclones of the Atlantic origin, the eastern part – those of the Pacific origin. The climate of the E.S.S. is polar marine but with continental characteristics.
In winter the most influence on the sea comes from the spur of the Siberian High which approaches the coast, but the ridge of the Polar High is not very influential here. This accounts for cold southwestern and south winds with the speed of 6–7 m/s blowing over the sea. They bring cold air from the continent, which is why the average temperature in January is only about −28… –30 °C. In winter the weather is quiet and cloudless spoilt only by cyclone intrusions in some days. The Atlantic cyclones in the western part of the sea cause strong winds and some warming, and the Pacific cyclones with cold continental air only increase the speed of wind and cloud cover and lead to snowstorms in the southeastern part of the sea. In the hilly areas of the coast, the Pacific cyclones cause local foehn with storms which accounts for a slight rise in temperature and a drop in air humidity.
In the summer the pressure over the Asian continent is low, and over the sea it is high, which is why northern winds are predominant. At the beginning of the season, they are very weak, but during the summer their speed gradually grows reaching 6–7 m/s. By the end of the summer, the western part of the E.S.S. becomes one of the stormiest parts of the Northern Sea Route. There is often wind blowing at the speed of 10–15 m/s. The strengthening of the wind here is due to foehns. The southeastern part of the sea is much calmer. Stable northern and northeastern winds determine the low air temperature. The average temperature in July in the north of the sea is 0–1 °C and 2–3 °C in the coastal areas. In summer time the E.S.S. mostly sees cloudy weather with drizzling rain and sometimes a mix of snow and rain.
In autumn the weather very rarely gets warm which is explained by the fact that the sea is remote from the ocean atmospheric centers and their influence on atmospheric processes is too weak. Typical climatic characteristics of the sea are a relatively cold summer in all the sea region, rough weather at the end of summer and especially in autumn in marginal regions of the sea, and still weather in its central part.
Continental runoff in the E.S.S. is relatively small, only 230–250 kmЗ/year, which presents 10 % of the total river runoff into all the Arctic Seas. The rivers flowing into the sea are the Indigirka, Alazeya, and Kolyma. The biggest of the flowing rivers, the Kolyma, brings to the sea about 120–130 km3 of water annually, the second biggest river, the Indigirka, −60 km3 a year, and the Alazeya only 10 km3 a year. All the other rivers in the same period of time bring to the sea around 35 km3 a year. The river water flows to the southern part of the sea, 90 % of the stream flow coming in summer months, like in other Arctic Seas. The water gets strongly desalinated on the area of 50,000 km2 which accounts for about 6 % of its total area.
Though the sea is quite large, the coastal stream flow does not influence its hydrological regime to a large extent, rather explaining some water peculiarities of the coastal areas in summer time. The main characteristic features of the hydrological regime of the E.S.S. are caused by high latitudes, free communication with the Central Arctic Basin, big ice coverage, and small river runoff.
As the sea is shallow and lacks deep trenches spreading outside the northern limits, most of its volume from the surface to the bottom is occupied by the surface Arctic waters. Only a limited number of areas close to the river mouths can boast of specific water originating as a result of a mix of river and seawater. It is marked by higher temperatures and low salinity. The surface water temperature in all seasons generally drops in the direction from the south to the north. In winter it approaches the freezing point and amounts to −0.2…–0.6 °C near the river mouths and closer to the sea borders reaches −1.7…–1.8 °C. In summer the range of surface temperature is determined by the ice conditions. Water temperature in bays reaches 7–8 °C, in open ice-free areas it reaches 2–3 °C, and at the ice edge, it is close to 0 °C.
Changes in water temperature depending on its depth in winter and spring are difficult to notice. Only close to the mouths of large rivers, it drops to −0.5 °C in subglacial areas and to −1.5 °C at the bottom. In the summer the ice-free districts show a slight drop in water temperatures from the surface to the bottom in the coastal area in the west of the sea. In its eastern part, the surface temperature can be found in the layer of 3–5 m deep, and then it drops abruptly at the depth of 5–7 m and then decreases smoothly closer to the bottom. In the zones of coastal runoff influence the area 7–10 m deep can boast of homogeneous temperature, between 10 and 20 m deep it drops, at first abruptly and then smoothly decreases to the bottom. Shallow, scarcely heated E.S.S. is one of the coldest Arctic Seas.
Water salinity on the surface generally grows from southwest to northeast. In winter and spring, it comprises 4–5 ‰ close to the mouth of the Kolyma and the Indigirka, reaches the point of 24–26 ‰ by the Medvezhyi Islands and the point of 28–30 ‰ in the central areas of the sea, and grows up to 31–32 ‰ in its remote northern parts. In summer due to the flow of river water and the ice melting, these figures drop to 18–22 ‰ in the coastal areas, 20–22 ‰ in the Medvezhyi Islands, and 24–26 ‰ in the north, at the melting ice edge.
In winter most of the sea gets slightly saltier from the surface to the bottom. Only in the northwestern district where the ocean waters come from the north, the salinity grows up to 23 ‰ in the upper layer 10–15 m deep and 30 ‰ at the bottom. Close to the river mouths, the upper desalted layer 10–15 m deep from the surface is underlain by water with more salinity. Starting from the end of spring and all through the summer, there is desalted layer 20–25 m thick forming in the ice-free areas. Under this layer the salinity grows with the depth of the sea. As a result in the shallow areas (up to the depth of 10–20 or even 25 m), all the water column gets desalted. In deeper areas in the north and east of the sea, in the areas 5–10 m and at times 10–15 m deep, the salinity surges and then grows smoothly up to the very bottom.
In autumn and winter, the water mass density is higher than in spring and summer. It is higher in the north and the east than in the west where desalted waters from the Laptev Sea permeate. But this difference is not really big. Usually the water mass density grows with the depth. Its vertical distribution is similar to the salinity scheme.
The waters have different layer patterns, which create different conditions for water circulation in different areas of the E.S.S. In relatively badly stratified and ice-free areas, heavy winds stir the water up to the level of 20–25 m in the summer. So in the areas where the water depth is not bigger than 25 m, the wind-driven circulation reaches the bottom.
In the areas of abrupt water stratification in terms of density, the wind-driven circulation reaches the level of only 10–15 m, where its significant vertical density gradients lie.
Autumn and winter water convection in the E.S.S. at the depth of 40–50 m (more that 70 % of its total area) reaches the bottom. By the end of the cold season, the winter vertical circulation spreads to the depth of 70–80 m, where it is limited by strong vertical water stability.
Constant currents on the surface of the E.S.S. create weak cyclonic circulation. Along the mainland coast, there is a regular water transfer from the west to the east. Close to Cape Billings, part of the water flows to the north and northwest and into the north marginal seas where it is mixed with the water flowing to the west. Water movement scheme changes according to different meteorological situations. Part of the water from the E.S.S. flows through the De Long Strait into the Chukchi Sea. Constant currents are often interfered by wind-driven ones, which are sometimes even stronger than the former. Flood tide streams are not very influential here.
The E.S.S. boasts of regular lunisolar semidiurnal tides. They are caused by a tidal surge which enters the sea from the north and moves toward the mainland coast. Its front is stretching from the north-northwest to the east-southeast, from the New Siberian Islands to Wrangel Island. The tides are more expressed in the north and northwest. Closer to the south, they get weaker as the ocean tidal surge slackens on the vast shallow area. So, in the part of the sea from the Indigirka to Cape Shelagskiy, the tides are almost unobservable. To the west and east of this district, the size of the tide is also very small comprising only 5–6 cm. In the mouth of the Indigirka, the shore configuration and the relief cause the growth of tides up to 20–25 cm. On the mainland coast, the water level changes are mostly caused by meteorological reasons.
The annual level variations are characterized by the highest position in June and July when the river flow is plentiful. A drop in coastal runoff in August leads to a 50–70 cm drop in the sea level. As a result of heavy winds in autumn (in October), the sea level rises. In winter the level decreases and in March or April it reaches its minimum.
Surges that violate the sea level up to 60–70 cm are very well expressed in summer season. In the mouth of the Kolyma and Dmitry Laptev Strait, they reach their maximum – 2.5 m. Fast and abrupt sea level variations are one of the typical features of the sea coastal areas.
Ice-free areas of the sea develop significant wave disturbance. It gets especially rough in times of stormy northwest and southeast winds which speed up over the surface of ice-free water. The waves reach the height of maximum 5 m, their normal height being 3–4 m. Strong wave disturbance is mostly typical at the end of summer and the beginning of autumn (September) when the ice edge retreats to the north. The western part of the sea is rougher than the eastern one. Its central areas are relatively quiet.
The E.S.S. is the most ice-infested sea in the Russian Arctic. It is fully covered with ice in the period from October–November to June–July. At this time the inwash of ice from the Arctic Basin to the sea is predominant unlike in other Arctic Seas where the outwash ice drift is more common. A characteristic feature of the E.S.S. ice is formation of strong land ice in winter. It is important to mention that it is mostly spread in the western shallow part of the sea and occupies a narrow coastal area in the east of the sea. In the west the width of the land ice reaches 400–500 km. Here it joins the Laptev Sea land ice. In the central areas its width comprises 250–300 km and closer to the east of Cape Shelagskiy 30–40 km. The ice margin approximately coincides with the isobath curve 25 m which lies 50 km northward from the New Siberian Islands and then turns to the southeast approaching the mainland coast near Cape Shelagskiy. By the end of the winter, the land ice thickness reaches 2 m. It reduces from the west to the east. Outside the border of the land ice, there lies the drift ice. Usually it is first-year or second-year ice 2–3 m thick. In the extreme north of the sea, it is possible to encounter multiyear pack ice. South winds prevailing in winter often drive the drift ice away from the northern ice edge. As a result there appear quite large areas of ice-free water and young ice that form Novosibirskaya (in the west) and Zavrangelevskaya (in the east) stationary ice polynyas.
In the beginning of the summer after the land ice breaks and gets eroded, the position of the ice edge is determined by wind and current action. However ice is permanent to the north of the line between Wrangel Island and the New Siberian Islands. In the western part of the sea in place of a vast area of land ice, there forms the New Siberian Ice Massif. It consists of predominantly first-year ice and by the end of the summer gets eroded. Most of the eastern area of the sea is occupied by a branch of Ayon Oceanic Ice Massif, which to a great extent forms heavy old ice. Its southern periphery during the year almost joins the mainland coast determining the ice situation in the sea.
The ESS is the most difficult sea among other seas in the Northern Sea Route, through which the transit traffic goes. The transportation of food and consumer products to the northern parts of East Siberia goes through Pevek Port.
The fauna in the coastal zone and the mouths of large rivers is relatively abundant. This is the place for those animals that are adjusted to the life in low-salinated water. In the central areas, it is possible to see cold water and brackish water animals. Among the fishes the most important are brook trout, Siberian white salmon, Arctic cisco, cisco, navaga, and flounder. Fish hunting is important on a local scale.
The main ports of the E.S.S. are Ambarchik in the mouth of the Kolyma and Pevek in the Chaun Bay. On the coast there have appeared new settlements and industrial enterprises. In the Soviet times the native population, the Yakuts (to the west of the Kolyma) and the Chukchi (to the east of the Kolyma), obtained a writing system. The region saw the opening of schools, medical institutions, as well as reindeer and hunting farms. On Wrangel Island there is a natural preserve – the main breeding ground of polar bears.