We have also seen that the coastal drainage and ice behavior play a large role la the forma- 

 tion of the water in the Soviet Arctic seas. The Atlantic water in them is therefore greatly diluted. 

 The question arises as to what can be considered as Atlantic water in the arctic? It is clear that 

 the limits both of temperature and salinity of this water can be only extremely arbitrary. 



According to Nansen, the signs of Atlantic water in the arctic are, first, positive temperature, 

 and second, high salinity (about 34.0 o/oo). The salinities determined by Nansen turned out to be 

 somewhat too high. Let us take, therefore, as the lower limit of salinity of Atlantic water a salinity 

 of 34. 5 o/oo. 



Figure 150 shows, according to Dobrovolski, the isotherms of the warm Atlantic layer at a 

 level of 300 m. The observations of the station "North Pole", the Sedov , and those of ships which 

 worked on the periphery of the Central Arctic Basin were employed for compiling this drawing. For 

 the region to the north of Wrangel Island, the drawing was completed with data of the Libin- 

 Cherevichny expedition of 1941. 



Table 111 shows the averaged values of temperature and salinity In the work region of the 

 Libin-Cherevichny expedition of 1941. Table 112 shows the vertical distribution of oxygen at one of 

 the observation points of this expedition. 



In both tables the warm Atlantic water is clearly defined. The maximum temperature was 

 observed at a level of 500 m and was equal to 0. 72° with salinity 34. 97 o/oo. Thus we may now 

 consider that the penetration of warm Atlantic water into the region to the north of Wrangel Island 

 has been decisively proven. 



As may be seen from table 112, the content of oxygen, supersaturating the water in the upper 

 levels, decreases comparatively little in the warm Atlantic layer. This fact indicates a small ex- 

 penditure of oxygen in this layer for oxidation processes, in particular for life activity of 

 organisms. 



From figure 150 it may be seen that the basic core of Atlantic water extends to the east from 

 the straits between Greenland and Spitzbergen, swerves to the right, and puts out tongues into the 

 troughs as it goes from the great depths into the northern parts of the surrounding seas. Two 

 tongues enter Barents Sea from the north — one between Spitzbergen and Victoria Island and the other 

 between Victoria Island and Franz Joseph Land. Two tongues also jut into the northern part of the 

 Kara Sea — one between the Sad'ko shoals and Severnaya Zemlya, and since the depths are greater 

 in the western trough than in the eastern, the warm layer here extends more to the south. * 



In the Laptev Sea only one tongue has been noted, and since the great depths here extend 

 farthest to the south, the warm layer also penetrates more to the south than in all the other troughs. 



The maximum temperature of the warm layer is not always found at the same level. Over 

 great depths it is generally observed at 400 m. On the periphery this depth decreases and in the 

 region to the north of Novaya Zemlya it drops to 150 m. Thus, in the furrows which stretch out 

 from the central basin, the Atlantic layer climbs up along the continental slope and further onto the 

 continental shelf. 



*The first signs of warm Atlantic water entering Kara Sea from the north were discovered by 

 Makarov in 1901. This fact was conclusively established by the Sedov in 1930. 



411 



