ABSTRACT 



The authority for, mission, forces assigned and method of operation 

 of the International Ice Patrol during the 1957 ice season are described. 



Aerial ice observation, surface ice patrol and communications statistics 

 are presented. 



All ice reports made to the International Ice Patrol in 1957 are tab- 

 ulated. A general month-by-month description of ice conditions in the 

 Grand Banks of Newfoundland area is given. A summary of ice con- 

 ditions in the Gulf of St. Lawrence and Strait of Belle Isle is included. 



The most outstanding features of the 1957 ice season were the severity 

 of the ice conditions and the employment of ships as a surface patrol for 

 the first time since 1950. The widespread and prolonged ice season, 

 evaluated as approximately 2.4 times heavier than average, make this 

 year appear notable in the annals of the International Ice Patrol. A 

 total of 931 known icebergs drifted south of the 48th parallel and 31 of 

 these reached below 43° N. 



The two dynamic topographic charts resulting from the season's current 

 surveys and the dynamic topography found at the Bonavista triangle 

 during the post season cruise are discussed with respect to surface cir- 

 culation. 



Temperature-salinity relationships of the Labrador Current water, 

 Atlantic Current water and mixed water, found in the Grand Banks region 

 during 1957, are compared with mean T-S curves for the period 1948-57. 

 The continuation of the trend of the last few years to increasing salinity 

 in the upper 200 meters in the Labrador Current and freshening of the 

 water below that level is noted. 



Year to year changes in density of the Labrador Current water are 

 noted for the periods 1934-41 and 1948-57. 



The apparent relation between the position of the cold wall in the 

 Grand Banks sector and sea level differences at Bermuda and Charleston 

 are further investigated in the light of more recent data, and it is con- 

 cluded that the correlation found in prewar years was fortuitous. 



A more detailed analysis of the circulation in the upper 1,000 meters 

 is made on the basis of volume and heat transports and mean and mini- 

 mum observed temperatures at 12 selected sections across the Labrador 

 Current occupied during the 1957 season and post season surveys. 



The exceptionally vigorous circulation on both the Labrador and 

 Greenland sides of the Labrador Sea in 1957 is noted. 



The temperature and salinity of the intermediate and deep waters of 

 the Labrador Sea in 1957 are examined and compared with averages for 



