cial shipping were the major 

 sources of iceberg sighting 

 reports this season. AES of 

 Canada was not able to pro- 

 vide as many reports this 

 season as last. Appendix A 

 lists all iceberg sighting re- 

 ports, including reports of ra- 

 dar targets, received from 

 commercial shipping, regard- 

 less of the sighting location. 

 In Appendix A, a sighting re- 

 port may represent several 

 targets. 



There Is an apparent 

 disparity between the number 

 of sightings reported in 1990 

 and 1989 and the relative 

 severity of the two seasons. 

 Although 1990 was a much 

 more severe season than 

 1989, the total sightings en- 

 tered into the drift model were 

 similar for the two years. This 

 disparity is partly explained by 

 cutbacks in AES Canada's 

 iceberg flights in 1990 and, 

 ironically, the severity of the 

 1990 season. The 1990 sea- 

 son was severe both in terms 

 of the number of icebergs 

 south of 48°N and the extreme 

 southern extent of icebergs. 

 Eight icebergs drifted south 

 of 40°N (normally considered 

 the southern boundary of 

 MP's operations area and the 

 southern extent of HP's com- 

 puter model which predicts 

 iceberg drift) during the year, 

 and the southernmost berg 



Page 6 



sighted during the season was 

 at 38-48°N, 47-1 9°W. Be- 

 cause of this severity, IIP had 

 to devote most of its aerial 

 patrols to surveys of the 

 southern iceberg limits. Thus, 

 IIP was unable to patrol the 

 interior of the operating area, 

 which normally contains the 

 largest number and highest 

 concentration of icebergs. 



Table 2 compares the 

 estimated number of icebergs 

 crossing 48°N for each month 

 of 1 990 with the monthly mean 

 number of icebergs crossing 

 48°N for each of the four re- 

 connaissance eras. During 

 the 1990 ice year, an esti- 



mated 793 icebergs drifted 

 south of 48°N latitude, com- 

 paredto301 during 1989. The 

 average number of icebergs 

 drifting south of 48°N per 

 year from 1 900 to 1 987 is 403 

 icebergs (Alfultis, 1987). IIP 

 defines those ice years with 

 less than 300 icebergs cross- 

 ing 48°N as light ice years; 

 those with 300 to 600 crossing 

 48°N as average; those with 

 600 to 900 crossing 48°N as 

 heavy; and those with more 

 than 900 crossing 48°N as 

 extreme. Thus, 1990 was a 

 heavy year. 



MP's computer model 

 consists of one routine which 



Table 2: Average Number of Icebergs South of 48°N - 

 The four periods shown are pre-lnternational Ice Patrol 

 (1900-1912), ship reconnaissance (1913-45), aircraft 

 visual reconnaissance (1946-82), and SLAR 

 reconnaissance (1983-89). 



