Discussion of Ice and 

 Environmental Conditions 



The number of icebergs that pass 

 south of 48' N in the International 

 Ice Patrol area each year is the 

 measure by which International 

 Ice Patrol has judged the severity 

 of each year since 1913 . The 

 average number of icebergs 

 drifting south of 48° N from 1913 

 to1987is395(Alfultis, 1987). 

 With 187 icebergs south of 48° N, 

 the 1988 ice year was less severe 

 than the 1913-1987 average. 



Since the number of icebergs 

 calved each year by Greenland's 

 glaciers is in excess of 10,000 

 (Knutson and Neill, 1978), a 

 sufficient number of icebergs exist 

 in Baffin Bay during any year. 

 Therefore, annual fluctuations in 

 the generation of Arctic icebergs is 

 not a significant factor in the 

 number of icebergs passing south 

 of 48' N annually. The factors that 

 determine the number of icebergs 

 passing south of 48' N each 

 season are the supply of icebergs 

 available to drift south onto the 

 Grand Banks, those affecting 

 iceberg transport (currents, winds, 

 and sea ice), and those affecting 

 the rate of iceberg deterioration 

 (wave action, sea surface tem- 

 perature, and sea ice). 



Sea ice acts to impede the trans- 

 port of icebergs by winds and 

 currents and also protects ice- 

 bergs from wave action, the major 

 agent of iceberg deterioration. 

 Although it slows current and wind 

 transport of icebergs, sea ice is 

 itself an active medium, for it is 

 continually moving toward the ice 

 edge where melt occurs. There- 

 fore, icebergs in sea ice will 



eventually reach open water 

 unless grounded. The melting of 

 sea ice itself is affected by snow 

 cover (which slows melting) and 

 air and sea water temperatures. 

 As sea ice melt accelerates in the 

 spring and early summer, trapped 

 icebergs are rapidly released and 

 then become subject to normal 

 transport and deterioration. 



The Labrador Current, aided by 

 northwesterly winds in winter, is 

 the main mechanism transporting 

 icebergs south to the Grand 

 Banks. In addition to transporting 

 icebergs south, the relatively cold 

 waters of the Labrador current 

 keep the deterioration of icebergs 

 in transit to a minimum. 



The 1988 International Ice Patrol 

 season did not open until mid-April 

 because of the small number of 

 icebergs drifting south of 52° or 

 48° N in January, February, and 

 March. With the sea ice not 

 extending as far south as normal 

 in February and March, the 

 icebergs were not protected as 

 long from deterioration. The 

 below average sea ice conditions 

 at the beginning of the season 

 would normally lead to a relatively 

 light ice season with a late start. 



Beginning in April and continuing 

 through August, large numbers of 

 icebergs began to drift south of 

 52° N and enter HP's area. There 

 was a good supply of icebergs 

 available to drift south of 48° N 

 from April to August, but the 

 environmental and oceanographic 

 conditions were not favorable for 

 the southward drift of icebergs. 

 Most of these icebergs did not drift 

 south with the Labrador Current to 

 the Tail of the Grand Banks, but 

 drifted east. By July and August, 

 iceberg deterioration became a 

 major factor preventing icebergs 

 from surviving a drift south of 48° 

 N. In summary, it appears the 

 environmental and oceanographic 

 conditions set up an unfavorable 

 eastward drift, preventing the large 

 number of icebergs entering HP's 

 area from drifting south of 48° N 

 with the Labrador Current. 



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