SLAR use, it is probable that some of the 

 targets identified as icebergs from the SLAR 

 were not icebergs but fishing boats. Although 

 the estimate of the number of icebergs drifting 

 south of 48 North may have been effected, the 

 1983-1985 seasons would still remain classi- 

 fied as extreme. As Ice Patrol's experience 

 with the SLAR increased, the probability of the 

 operatorwrongly identifying atarget has been 

 reduced but not eliminated. 



In light of the targetdiscrimination prob- 

 lem, visual confirmation is still sought for ice- 

 bergs that set the limits of the area of iceberg 

 danger. Flights are planned during the de- 

 ployment period to make the best use of avail- 

 able visibility. 



Other Sighting Sources 



The estimate of the icebergs south of 

 48 North is made from all data collected and 

 analyzed by Ice Patrol throughout the year. 

 Ice Patrol actively solicits other reporting 

 sources to supplement Ice Patrol's own data 

 gathering efforts. Ice Patrol relies on reports 

 from commercial shipping to help improve the 

 quality and accuracy of the products delivered 

 to the maritime community. As an example, in 

 1991 reports from shipping accounted for over 

 50 percent of the icebergs entered into the drift 

 prediction model. 



Throughout the period covered by this 

 paper, other sources of iceberg sighting re- 

 ports have been added. With the addition of 

 each new source, the potential for increasing 

 the annual estimate of the icebergs drifting 

 south of 48 North increases, particularly when 

 the new source's efforts are concentrated in 

 areas not othen/vise fully covered. 



The sighting source for icebergs was 

 recorded as one of three types from 1960 to 

 1 981 . The three source categories used were 

 USCG aircraft, USCG ship report, and other. 

 IJSCG vessels transiting to and from ocean 

 stations in the North Atlantic and vessels per- 

 forming oceanographic research on the Grand 

 Banks for Ice Patrol provided the sighting 

 reports recorded under this category. Ex- 

 amples of reports received within the "other" 

 category includes commercial shipping re- 

 ports, reports from commercial, U.S., and 



Canadian military aviation, and reports from 

 lighthouses. Between 1981 and 1983, the 

 sources of sighting reports entered into the 

 drift model were not recorded and are now no 

 longer available. In 1984, a ten category 

 sighting source code was added to the drift 

 model as part of the data entry procedure. 



In the early 1 980s, the Canadian Atmo- 

 spheric Environment Service (AES) began 

 flying dedicated iceberg reconnaissance flights. 

 Funding for this program has varied and the 

 number of reports received is directly propor- 

 tional to funding. The AES iceberg reconnais- 

 sance efforts to date peaked during the 1987 

 and 1988 seasons. AES used an APS-94E 

 SI_AR as the primary iceberg sensor on their 

 Electra patrol aircraft through 1 990. The APS- 

 94E was evaluated in 1984 and its detection 

 capability was less than the APS-1 35 (Rossiter, 

 et al., 1985). In 1988, a DASH-7 with a CAL 

 SLAR was introduced into service by AES. 

 The AES iceberg flight efforts within the Ice 

 Patrol model area are concentrated near the 

 sea ice edge within the Canadian exclusive 

 economic zone. The sea ice edge is within the 

 area of higher Iceberg density. AES iceberg 

 dedicated flights emphasize visual searches. 

 AES reports SLAR targets which are not visu- 

 ally confirmed icebergs as radar targets. 



In about 1984, Ice Patrol began to re- 

 ceive iceberg reports through the NOAA/U.S. 

 Navy Joint Ice Center. The information comes 

 from a variety of Department of Defense 

 sources and is passed to Ice Patrol for entry 

 into the drift prediction model. The sighting 

 reports are spread throughout the model area. 

 In 1986, this source accounted for an all-time 

 high of 1 1 percent of the icebergs entered into 

 the model. 



In the 1 980s, exploratory efforts to de- 

 velopthe hydrocarbon resources on the Grand 

 Banks began. The Hibernia oil field area lies 

 between about 46 to 49 North on the eastern 

 portion of the Grand Banks. The Canadian 

 government regulations concerning drilling 

 requires the operators to conduct surveillance 

 for icebergs in their exploration area. Begin- 

 ning in about 1 985, the sightings made by the 

 hydrocariDon industry were voluntarily sup- 

 plied to Ice Patrol. This period of activity only 

 lasted about 4 years and led to an increase in 



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