FOREWORD 



Successful arctic operations require considerable preparation 

 and planning. To aid such planning, the Oceanographic Office has been 

 engaged in developing vstrious techniques for forecasting formation, 

 growth, movement, and disintegration of sea ice, especially in harbor 

 areas, since each arctic and subarctic harbor constitutes a special 

 environmental problem. 



This report is based on available sea ice information and frost 

 degree data for 58 arctic stations. Freezeup and breakup dates for 

 39 stations are included. The earliest, latest, and average dates of 

 freezeup or breakup are given in calendar dates. 



KKOLL 



Rear AdBiral, U.S. Navy 

 Commander 

 U.S. Naval Oceanographic Office 



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