DISCUSSION OF ICE AND 

 ENVIRONMENTAL 

 CONDITIONS 



Since more than 10,000 icebergs 

 are calved by Greenland's glaciers 

 into the Baffin Bay each year 

 (Knutson and Neill, 1978), annual 

 fluctuations in the generation of 

 Arctic icebergs are not a significant 

 factor influencing the number of 

 icebergs passing south of 48 N 

 annually. The factors that deter- 

 mine the number of icebergs pass- 

 ing south of 48° N each season are 

 the supply of icebergs available to 

 drift south onto the Grand Banks, 

 those factors affecting iceberg 

 transport (currents, winds, and sea 

 ice), and those affecting the rate of 

 iceberg deterioration (wave action, 

 sea surface temperature, and sea 

 ice). 



Sea ice acts to impede the transport 

 of icebergs by winds and currents 

 and also protects icebergs from wave 

 action, the major agent of iceberg 

 deterioration. Although it slows 

 current and wind transport of ice- 

 bergs, sea ice is itself an active 

 medium, continually moving toward 

 the ice edge where melt occurs. 

 Therefore, icebergs in sea ice will 

 eventually reach open water unless 

 grounded. The melting of sea ice is 

 affected by snow cover (which slows 

 melting) and air and sea water 

 temperatures. As sea ice melt ac- 

 celerates in the spring and early 

 summer, trapped icebergs are rap- 

 idly released and then become 

 subject to normal transport and de- 

 terioration. 



The Labrador Current, aided by 

 northwesterly winds in winter, is the 

 main mechanism transporting ice- 

 bergs south to the Grand Banks. In 

 addition to transporting icebergs 

 south, the relatively cold waters of 

 the Labrador Current keep the dete- 

 rioration of icebergs in transit to a 

 minimum. 



During December, 1988, a more 

 intense than normal low pressure 

 to the south of Greenland resulted 

 in stronger than normal northwest- 

 erly winds over eastern Canadian 

 waters. This combined with below 

 normal temperatures to produce an 

 early freeze-up. During January, 

 February, and March, temperatures 

 continued to be below normal for 

 Newfoundland and Labrador, and 

 freezing degree accumulations 

 were higher than normal. There- 

 fore, the growth and spread of ice 

 were ahead of normal, and mean 

 pack ice was thicker and extended 

 further south than normal for these 

 three months. More westerly than 

 normal winds during February and 

 March also caused the ice to extend 

 further east than normal off the 

 Newfoundland and Labrador 

 coasts. 



Because sea ice conditions were 

 above normal for the first part of the 

 1989 season and the sea ice edge 

 was farther south than normal, ice- 

 bergs were protected from deterio- 

 ration longer and released farther 

 south than normal. As expected, 

 this resulted in a fairly large number 

 of icebergs south of 48°N during 

 Febnjary and March, and the sea- 

 son opened on 1 March 1989. 



Although sea ice conditions were 

 greater than normal during the first 

 three months of the year, 1 989 was 

 only an average iceberg year. 

 Slightly warmer than normal tem- 

 peratures and a southwesterly wind 

 during the first part of May caused 

 the sea ice to retreat faster than 

 normal along the Labrador Coast at 

 the end of May. Slightly warmer 

 than normal temperatures persisted 

 throughout the remainder of the ice 

 season as well. 



In summary, ice conditions during 

 the first few months of 1989 were 

 more severe than normal, but those 

 toward the end of the ice season 

 were less severe, resulting in an 

 average iceberg year. 



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