USCGC Evergreen made three oceanographic surveys in the 

 critical sectors of the Grand Banks area during the ice season. 

 By means of the current maps resulting from these surveys, semi- 

 monthly isotherm charts prepared from sea temperatures reported 

 by shipping and wind data supplied by the U. S. Fleet Weather 

 Central at Argentia, estimates of the set, drift and melting rate 

 of bergs and field ice were made. These estimates were useful in 

 planning ice observation flights, particularly after extended 

 periods during which such flights were impracticable because 

 of poor visibility conditions. The current charts and isotherm 

 charts for the season are shown in figures 12 to 14 and 1 to 7, 

 respectively. 



Only 80 bergs drifted south of latitude 48 °N in the Grand Banks 

 area during all of 1956, a low figure in comparison with the 

 1900-1956 average, 391 bergs. None of these bergs approached 

 very close to the United States-European North Atlantic Track 

 Agreement tracks B and C. The Canadian-European tracks E 

 and F were free of field ice during the periods they were regularly 

 scheduled to be in effect, but were encumbered by a few bergs 

 throughout the ice season. The field ice blocking Track G was prac- 

 tically all gone by 16 June, but bergs were to be found throughout 

 the season in the Strait of Belle Isle and eastward on this track 

 to the 1,000 fathom curve. The steamer track from Cabot Strait 

 to the St. Lawrence River ports was essentially free of ice by 

 4 April. 



The International Ice Patrol office at Argentia was closed and 

 broadcast of ice bulletins terminated on 13 July. By that time 

 there was no ice far enough south in the Labrador Current to 

 survive the trip to the vicinity of the Tail of the Banks and en- 

 danger the major steamer tracks traversing that area. Periodic 

 post-season ice reconnaissance flights were made by the United 

 States Coast Guard Air Detachment at Argentia to guard against 

 any stray berg reaching those tracks without warning to shipping. 



