Various assumptions can be made concerning the meteorological conditions and, correspond- 

 ingly! it is possible to speak of different rates of heat release to the atmosphere by an ice-free 

 surface. In any case, the assumed mixing will delay the appearance of the ice, and then the re- 

 lease of heat from the open water surface will be faster than in our example, (i.e. , through ice). 

 In this regard, the calculation of the number of freezing degree-days given in table 73 will also 

 change. However, the total amount of heat released by the sea to the atmosphere remains un- 

 changed; only the order of magnitude of its components changes . For example, according to the 

 table, at first 6.0 kg-cal/cm2 were expended on crystallization, then 4.8 kg-cal/cm2 on cooling 

 the second layer, after this, 3.0 kg-cal/cm2 again on crystallization, etc. Under such conditions, 

 the ice was two-layered, with the division into layers at a depth of 83 cm. During preliminary 

 mixing down to 25 m, at first 4.8 kg-cal/cm2 were expended on cooling, and then 9.0 kg-cal/cm2 

 on crystallization. The ice formed would be single-layered. 



8. In Section 7, it was assumed that the storm which mixed the first and second layers be- 

 gan at the exact moment that the upper layer reached the freezing point, but these layers can mix 

 even after the sea is covered with a thin ice layer, provided the force and duration of the wind is 

 sufficient to break it. Since the heat reserve (computing from the freezing point) in the second 

 layer is 4.8 kg-cal/cm2, this reserve is sufficient to melt up to 67 cm-thick ice. 



Thus, we see that the vertical distribution of temperature and salinity in the water beneath 

 ice has a substantial effect on the stratification and thickness of ice formed under the same mete- 

 orological conditions. Apropos, I have received information of practical interest from M. M. 

 Somov. 



During the first days of July 1943, the icebreaker Mi Koyan discovered "spring ice" in 

 the region of Russky Island (Ostrov Russkii) (near the Taimyr coast of the Kara Sea). For several 

 days prior to this , unbroken shore ice still remained right up to the Kirov Islands . From this , 

 Somov concludes that the spring ice discovered by the Mikoyan existed in the midst of continuous, 

 fast ice and this ice could not have been brought in from another area; we can only assume that 

 this ice is not of spring origin, but is thinner than the surrounding ice due to some additional 

 amounts of heat carried into this region during the winter. 



In Somov 's opinion, such ice could not have been discovered earlier. Airplanes are unable 

 to distinguish it from the air, and vessels ordinarily begin to navigate only when spring and 

 autumn ice are so intermixed that it is difficult to resolve such a question. It seems to me that 

 these discussions and the example taken indicate that extensive areas of thicker or thinner ice can 

 be created by the pre-wtnter vertical distribution of oceanographic characteristics, which are 

 caused basically by sea currents, and by intense wind mixing during this period. 



Oceanographic profiles made in regions where climatic conditions can be considered com- 

 pletely identical sometimes show a great variation of the vertical temp)erature and salinity distri- 

 bution due primarily to sea currents . This is the primary reason for the difference in the freezing 

 indexes; another factor is the thickness of the ice which forms. As a rule, the warmer the sub- 

 surface layers, the greater are the freezing indexes and the thinner the ice. 



The warm saline Atlantic waters which enter the Arctic Basin via the Greenland current, 

 play an important role in the water balance of the Arctic Basin . The surface layers of the Arctic 

 Basin are freshened by shore runoff and ice melt and they are salinified by ice formation and by 

 mixing with the deep Atlantic waters . Part of the freshened water and ice is carried out of the 

 basin by the East Greenland current. As a result, specific salinity and temperature equilibrium 



219 



