Appendix C 



An Historical Perspective to the Mild 1999 Ice Year 

 Donald L. Murphy 



Introduction 



By any measure, the 1999 ice 

 year was extraordinary. In an average 

 year, nearly 500 icebergs pass south of 

 48°N, the traditional boundary below 

 which icebergs are considered to be a 

 menace to transatlantic shipping. In 

 1999, 22 icebergs passed south of 

 48°N. In a typical year. International 

 Ice Patrol (IIP) issues routine iceberg 

 warnings to mariners from February 

 through July. In 1999, Ice Patrol 

 issued no formal warnings. HP's aerial 

 reconnaissance usually extends well 

 into August. In 1999, routine aerial 

 reconnaissance was suspended after 

 the return of Ice Reconnaissance 

 Detachment #6 on 4 June 1999. The 

 average iceberg season length is 147 

 days. There was no formal season in 

 1999. What made the 1999 iceberg 

 season even more remarkable was the 

 fact that there was no lack of icebergs 

 in the western North Atlantic. Indeed, 

 there were several thousand icebergs 

 along the northern Newfoundland and 

 Labrador coasts in May and June (See 

 the Ice and Environmental Conditions 

 section of this report), but only a few 

 moved toward the shipping lanes. 



This Appendix provides an 

 historical context to the 1999 season. 

 No attempt is made to answer the 

 question "Why did so few icebergs 

 pass south of 48°N in 1999?", though 

 the review of the history provides 

 several important clues. There is an 

 extensive body of literature (Marko, et 

 al., 1994) by investigators who have 



struggled to explain the variability in the 

 number of observed icebergs over the 

 many decades that IIP has been 

 keeping records. 



1999's Place in History 



The scarcity of icebergs passing 

 south of 48°N latitude in 1999 is 

 unusual, but not unprecedented. Ten 

 times in Ice Patrol's history there have 

 been fewer than 25 icebergs reported 

 south of 48°N (Table 1). The 1999 ice 

 season enters into a tie with the 1977 

 season as the ninth-mildest iceberg 

 season in Ice Patrol's history. 



Rank 



Year Iceberas 



Table 1. Years with the lowest number of icebergs 

 estimated to have drifted south of 48'N. 



Note: Table 1 reflects the current 

 definition of the ice year, which runs 

 from October through September. At 

 various times in Ice Patrol's history it 

 has been defined differently, for 

 example, in 1940 and 1941, the ice 

 year was the calendar year. In both 

 years, it was reported in MP's annual 

 reports that two icebergs passed south 

 of 48°N. One of these icebergs 



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