Somov's method was carried out by Biriulin and Somov for the calculation of the average 

 thickness of ice in the southern part of the Laptev Sea for the past years. The borders of the 

 region to which the calculations refer, are shown in figure 105. 



S0° WO 



110° 120° 130' 140° 



Figure 105. Borders of the examined part of the Laptev Sea. 



The calculations of the accretion of ice were carried out according to the formula proposed 

 by me, in which the necessary number of degree days of frost was computed as the arithmetical 

 mean for the observations of the stations which were located on the periphery of the region and 

 namely; the "Cape Cheliuskin, " "Tiksi Bay," "Schalamrov" and "Koletsnoi Island." 



Two points on latitude 75° and 80° along the meridian 125° were chosen for the calculations 

 of the elements of the drift. According to my method (see Sections 135 and 136) and chiefly on the 

 assumption that the wind drift occurs along the isobars and with a velocity inversely proportional 

 to the distance between the isobars; according to monthly charts of pressures, the directions and 

 velocities of drifts for 3 points were calculated and later averaged. The average thickness of the 

 ice in the Laptev Sea without the calculations of the drift — according to formula (2) — and the 

 average thickness of the ice with the calculation of the drift as shown in figure 106 according to 

 Biriulin and Somov. 



It is distinctly clear from the picture that the influence of the drift on the average thickness 

 of the ice begins to significantly show an effect from February, gradually increasing in effect until 

 May, inclusive. The difference between the thickness of the ice which is computed without reckon- 

 ing of the drift and of the thickness which is computed with reckoning of the drift may reach 70 cm, 

 which comprises about 40 per cent of the maximum thickness of the ice. 



Proceeding from the average thickness of the ice to the total quantity of the ice in the sea, 

 is possible to conclude that due to the drift, 40 per cent of the total quantity of the ice which is 

 formed m the course of the winter appears to be transported from the sea (until May). 



it 



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