Ice information was collected by the International Ice Patrol during 

 the ice season from several different sources, viz: 



(a) International Ice Patrol aerial ice reconnaissance in the Grand 

 Banks area and northward to the Strait of Belle Isle, 



(b) commercial and military vessels and aircraft traversing ice- 

 infested areas, 



(c) Canadian Department of Transport aerial ice reconnaissance m 

 the Gulf of St. Lawrence and approaches, 



(d) U. S. Hydrographic Office ice reports covermg the Labrador 

 Sea and Baffin Bay, 



(e) various other sources of information regarding local ice condi- 

 tions in harbors and the approaches thereto, e. g., harbormasters, 

 harbor pilots, signal stations, shipping company representatives. 



Ice drift and rate of melting were estimated by means of current 

 charts constructed from oceanographic data collected by USCGC 

 Evergreen on three surveys in the ice patrol area,^ sea surface isotherm 

 charts prepared semimonthly from the sea temperatures reported by 

 shipping and wind data provided by the U. S. Navy Fleet Weather 

 Central at Argentia. The current charts and isotherm charts for the 

 season are shown in figures 13 to 15 and 1 to 8, respectively. 



The 1955 ice season in the Grand Banks area was lighter than the 

 average and was the fifth consecutive season m which fewer than the 

 average number of bergs drifted south across latitude 48° N 

 shown in the following table: 



as 



Year 



1950 

 1951 

 1952 

 1953 

 1954 



No. of bergs 

 crossing Lat. 



48° N. 



460 



6 



14 



56 



312 



Year 



1955 



1900-1955 average 



1900-1955 maximum (in 

 1929) 



No. of bergs 



crossing Lat. 



48° N. 



61 

 396 



1351 



The distribution as well as the number of bergs which crossed the 48th 

 parallel during the season was quite different from the normal. No 

 bergs were carried by the Labrador Current down the east slope of 

 the Grand Banks or east toward the Flemish Cap area. Instead, 

 most of the bergs which entered the Grand Banks area ended in 

 positions along the east and south coasts of the Avalon Peninsula and 

 the remainder in the central and northwestern sectors of the Grand 

 Banks. At no time during the season were the United States- 

 European North Atlantic Track Agreement tracks B and C endangered 

 by ice. Of the Canadian-European routes, track D, in effect until 

 10 April, was not endangered by ice during the season; track E, while 

 in effect from 11 April to 15 May, was easily navigable but encum- 



1 DetaUs of the oceanographic program are presented in another section of this bulletin. 



