waters. The Atlantic Water core entering the Kara Sea through the 



two troughs rises from a depth of 300 meters to a depth of 150 meters 



within 50 nautical miles as it encounters the continental shelf. 



Above 150 meters, Atlantic Water loses Its distinguishing characteristics 



by admixture with other waters. 



D. Arctic Water. 



The primary source of Arctic Water found in the Arctic Basin 

 is Continental Runoff from the Arctic Ocean's peripheral seas (Cross 

 section 0-0', Fig. A-16) . Coachman (1962) divided Arctic Water into 

 the following three sublayers: The shallow layer (0 to 25-50 meters), 

 a relatively dilute, generally cold layer formed primarily by summer 

 melting of pack ice; the subsurface layer (25-50 to 100 meters), a 

 cold layer which increases In salinity with depth (33-34 %o); and 

 the mixed layer (100 to 200 meters) , a layer with increased temperatures 

 and a slight increase in salinity marking the approach to the Atlantic 

 Water core at 300 meters. 



Coachman (1962) refers to these sublayers as Surface Water, and 

 Nansen (1902) refers to them as North Polar Water. The temperature/ 

 salinity relationship is such that the water mass must be advected 

 into the Arctic Basin from some outlying area. The NORTHWIND survey 

 has allowed a re-examination of the questions of where the water 

 originates and what waters mix. 



One explanation of the anomalously high salinities found in the 

 Surface Water in the Kara and Laptev Seas is intensive mixing of 

 the saline Atlantic Water brought via the Svyataya Anna and Voronin 

 Troughs with river effluent (Coachman, 1962)... this mixing results 

 in the formation of the subsurface layer of Arctic Water at 25-50 

 to 100 meters which overlies the Arctic Basin. Another explanation 

 for the high salinity is the sizeable amount of Atlantic Water entering 

 the Kara Sea from the Barents Sea as discussed above. Zenkevitch 

 (1963), on the other hand, states that the high salinity values can 

 be attributed to the formation of ice in winter. 



Examination of the northernmost line of stations allows study 

 of this freezing process in action. It may be seen from the T-S plot 

 (Fig. 28) that Arctic Water is being formed at the surface in this 

 location. It should also be noted that the temperatures of the Arctic 

 Water mass approximate the freezing point of sea water for those particular 

 salinities. 



The extent of Arctic Water in the Kara Sea can be determined 

 by examining three temperature cross sections, J-J' (Fig. A-11) , 0-0' 

 (Fig. A-16), and V-V (Fig. A-23) . The core of Arctic Water in these 

 sections will be considered to be the -l.S'C Isotherm. This isotherm 

 places the core at approximately 75 meters. The isotherms in section 

 J-J' show the pinching out of the Arctic Water at station 77 as Arctic 



42 



