In the same figure, let the Y-axis represent the ice thickness computed according to formula 

 (1). The resulting curve will also characterize the ice thickness along the axis of the channel. 



If we increase the rate of drift and retain the same scale in the figure, we should increase the 

 distance between the points corresponding to the given number of freezing degree-days. If the rate 

 of drift decreases, the distance between the contiguous numbers of freezing degree-days will also 

 decrease accordingly. 



The stated problem can also be solved in another manner. Actually, in formula (1) R is 



/?=eT, 



where 9 is the temperature difference between air and water, which we assume to be constant and 

 T is the number of days. 



However, 



where -D is the distance in knots traversed by the ice in a day, y is the rate of drift (in knots) per 

 day and T is the drift duration . 



Hence, we get 



/■2-I-50Z = — D, (2) 



where D is the distance of a given point in the channel from the beginning of the channel expressed 

 in knots . 



According to this last formula, the distance along the axis of the channel, counting from the 

 beginning of the channel, can be plotted along the X-axis, instead of the number of freezing 

 degree -days . 



With certain reservations, the problem as stated, can be adapted to the Kara Sea, e.g. , 

 where there is a constant northward removal of ice from the Yamal Peninsula at a rate of about 

 1.0 to 1.5 knots per day. It is clear that the problem can be complicated by making assumptions 

 concerning the distributions of velocities and temperatures along the axis of ice removal, etc. 



As an example, the lower scale in figure 78 shows the distances along the axis of removal in 

 knots, computing from the beginning of removal, on the condition that the temperature difference 

 air-water is 25 ° and the rate of removal is 1 knot/ day. 



Only the thickness of the accretion ice can be characterized by the given example. However, 

 this method can be developed somewhat. Actually, if we know the drift of the ice field for a cer- 

 tain period of time and the number of freezing degree-days to which the ice field has been subjected 

 during the same time interval, we can compute the thickness of this ice at any point of the drift by 

 formula (1) . 



As a rule, the ice in the seas of the Soviet Arctic is in constant motion both summer and 

 winter. Open water areas of various sizes appear from time to time due to the collisions of in- 

 dividual floes and fields and the subsequent hummocking, which decreases the ice area. Sometimes 

 even thick shore ice is broken up by strong winds and is carried far from the shores . At negative 

 air temperatures, new ice immediately begins to form in the open water thus created. 



224 



