The increase in ice thickness with time is shown in 

 figure 15. 



Discontinuities exist at the beginning of each 

 season, caused in 1952 by the destruction of the fast 

 ice sheet and in 1953 by the influx of drift ice which 

 remained and developed as the permanent fast ice 

 sheet. Prior to the destruction of the ice on 5 January 

 1953 by high winds and above freezing temperatures, 

 an estimated thickness of 14 to 18 inches had been 

 attained. 



The break-up of the fast ice on 29 May may be 

 indicative of the mild ice conditions experienced off 

 the northern and northwestern Alaskan coast during 

 the summer of 1954 and is approximately two weeks 

 earlier than the average observed time for the 5-year 

 period from 1951 to 1955. 



A comparison of ice thickness and accumulated 

 degree days below 29°F is given in figure 16. For 

 each season, degree days are calculated starting 

 with the dote the first slush ice was observed. The 

 average daily temperature is computed as the mean 

 of the maximum and minimum air temperature re- 

 corded at Wales. Based on the Field Station weather 

 observations, the meteorological factors of cloud 

 cover, wind speed, and humidity and the insulating 

 effect of snow cover on rate of ice growth are gen- 

 erally comparable for the two ice seasons considered 

 here. The snow cover on the ice did not exceed 4 

 inches throughout the measurement periods. Minor 

 irregularities in the comparison of degree days and 

 ice thickness are expected, due to the limited tem- 

 perature data and to the method of calculating aver- 

 age daily temperatures. 



The discontinuities during the initial formation 

 of the fast ice should be kept in mind, since these 

 have a definite bearing on the slope of the ice 

 formation curve and no doubt account for much of 

 the divergence during early stages of growth. Com- 

 parable rates of growth are indicative for both 

 seasons after an ice thickness of 31.5 inches was 

 reached. 



The complexity of the variables affecting the 

 ice growth rate is recognized and field studies are 

 now in progress to obtain more complete meteor- 

 ological, oceanographic, and temperature profile 

 (air-ice-water) data. These observations will be an- 

 alyzed in greater detail than the preceding data 

 and the observed ice growth compared with the- 

 oretical values computed by various methods dis- 

 cussed and summarized by Calaway.*^ 









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