DISCUSSION OF ICEBERG AND ENVIRONMENTAL CONDITIONS 



1974 ICE SEASON 



The 1974 Season total of 1386 icebergs south of 

 48°N was the second heaviest in Ice Patrol his- 

 tory, surpassing the 1929 count of 1329. Of 

 almost equal historical significance is that never 

 before had there been three very heavy years in 

 succession, that of 1584 icebergs during the 1972 

 Season and 947 during 1973. In attempting to 

 explain the severity of the 1974 Season, the en- 

 vironmental factors, including the number of ice- 

 bergs available to drift south of 48°N, the 

 strength and duration of the northwesterly winds 

 that help produce southerly iceberg transport, 

 the sea ice cover that protects the icebergs, the 

 development of the Labrador Current features 

 (discussed in the Oceanographic Conditions, 1974 

 section), and the deterioration of icebergs are 

 analyized in the following paragraphs. 



During the January preseason flight a total of 

 1281 icebergs were sighted as shown in figure 1. 

 Almost 600 of these bergs were counted by ex- 

 tending the survey area northward to Cape 

 Christian, but it was still over a hundred bergs 

 shy of the season total. Either of two suggestions 

 are offered: the environmental conditions were 

 extreme allowing for icebergs to drift from north 

 of Cape Christian to south of 48°N or, East 

 Greenland icebergs provided a more significant 

 input to the seasonal berg total by drifting west- 

 ward across the northern Labrador Sea and the 

 Davis Strait. The February preseason survey 

 totaled 2403 icebergs, as shown in figure 3, pro- 

 viding a reasonable explanation for its ex- 

 tremely heavy year and still allowing for berg 

 casualties on the 1000 plus mile journey down the 

 coast of Labrador into the Grand Banks area. 

 In both January and February a large number 

 of icebergs were located in the middle of the 

 Davis Strait. As will be shown in the environ- 

 mental conditions, icebergs from both north of 

 Cape Christian and southeast of Davis Strait had 

 the potential to move into the area between the 

 January and February surveys. 



Figures 26a through 26h show the normal and 

 the 1974 surface pressure patterns for January 

 through August. Because the January preseason 

 survey revealed only three icebergs south of 56°N, 

 those off Hamilton Inlet, it was not deemed 

 necessary to analyze any of the prior months. The 

 mean pressure pattern for January 1974 was 

 dominated by the Icelandic Low, located 60°N 

 27°W, with a pressure of 973 mb. With the nor- 

 mal of almost lOOOmb, a 27-mb anomoly was 

 centered in the Low. Not only was the Icelandic 

 Low more intense, the Azores High was higher 

 in pressure at 1027 mb, and covered more area in 

 the east-west direction. Thus the winds along 

 the Baffin Island and Labrador coasts were ex- 

 treme northerlies, possibly even a record, and 

 provided for maximum iceberg southerly drift,. 

 Thus, the increased berg count in the February 

 over the January survey can be accounted for. 



The February 30-day mean pressure pattern 

 was near normal in configuration, but the Ice- 

 landic Low, although recovering to 993 mb, was 

 still over 10-mb lower than normal and displaced 

 some 400 miles east of its usual position. The 

 Azores High was normally located, but at 1025 

 mb it was 4 mb higher than usual. Thus, com- 

 pared to January, the anomalies were small, but 

 there was still a significant negative 9-mb anom- 

 aly off Labrador with an anomalous trough over 

 Newfoundland. This enhanced the transport of 

 icebergs across the Davis Strait and south along 

 the Labrador coast. 



The March mean pressure pattern was normal 

 in appearance like February, but the central 

 pressures were more extreme. The Icelandic Low 

 at 993 mb was more than 12 mb deeper than usual 

 and located 100 miles south of Kap Farvel, 

 slightly west of its normal position. With the 

 Azores High 5 mb higher than normal, major 



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