Section 106. The Increase in the Power of the Ice Cover 

 as a Result of Drift and Ice Hummocking 



As the observations of the Fram and the Sedov showed, parts of the ice which were formed 

 exclusively as a result of accretion, can be preserved in the Arctic Basin for a long time (2 to 3 

 years) but all the same, they do not determine the basic masses of ice, but the ices of the pile-up. 



An endeavor to consider the influence of ice hummocking and the cleared spaces of water 

 which resulted from ice hummocking and drift, on the increase of the total force of the ice cover 

 was made by Somov and later led to the quantitative expression in the work of Biriulin and Somov. 



Calculating the average thickness of the ice as the quotient for the division of the general 

 volume of ice by the area of the examined part of the sea, Somov points out that this thickness of 

 ice is summed up from the interaction of the following factors: 



1. Accretion from below due to heat emission into the atmosphere. 



2. The bearing out of the ice from the sea and returning it from other seas. 



3. Formations of young ice in clear water, which is caused as a result of drift and 

 hummocking. 



4. Ice melting. 



It is natural that during the period of ice formation it is necessary to consider the first three 

 factors, but during the period of melting, only the second and fourth. 



E\irthermore, for the solution of the problem, Somov makes the following assumptions: 



1. The area of the sea is equi-dimensional to a certain rectangular sea, whose width is 

 equal to the average width of the given sea, and the length is equal to the average length of the 

 given sea. 



2. The sea on three sides is bordered by shores; the fourth side of it is in free communica- 

 tion with the Arctic Basin. 



The Laptev Sea answers such a condition in the first approximation (if possibility of an ice 

 exchange with the Kara and the East Siberian Seas across the straits of the archipelagos of 

 Severnaya Zemlya and the north Siberian Islands is disregarded). 



3. The sea is encompassed at the same time by the drift (average for a 10 day period or for 

 a month); the drift flows over the entire area of the sea with an equal velocity and in the same 

 direction. This assumption has been indicated to some degree by the simultaneous drifts in the 

 winter of 1937-1938 of the fleet of the ships: of the ice breaker Lenin in the southwestern part, 

 and of the steamer icebreaker SadKou in the northeastern part of the Laptev Sea. 



4. With the drift of ice, which is accompanied by hummocking or carr3dng of ice from the 

 sea, the sum of the areas of water free from ice is equi-dimensional to that area, which would be 

 received as a result of the simultaneous movement of ice on the entire sea in the form of a solid 

 cover with a given velocity and direction of drift. 



289 



