are in Table 1. The 4370 

 sightingsenteredintollP'sdrift 

 model represented only a 

 fraction of the total sightings 

 reported to IIP. Sightings of 

 targets outside I IP's operations 

 area or grounded or in areas 

 of little or poorly defined cur- 

 rent along the Newfoundland 

 coast were not entered into 

 the model. 



Table 2 compares the 

 estimated number of icebergs 

 crossing 48°N for each month 

 of 1991 with the monthly mean 

 number of icebergs crossing 

 48°N from 1983 - 1990, the 

 period during which IIP has 

 been patrolling with SLAR- 

 equipped aircraft. During the 

 1991 ice year, an estimated 

 1 974 icebergs drifted south of 

 48°N latitude, compared to 793 

 during 1990. llPdefinesthose 

 ice years with less than 300 

 icebergs crossing 48°N as light 

 ice years; those with 300 to 

 600 crossing 48°N as aver- 

 age; those with 600 to 900 

 crossing 48°N as heavy; and 

 those with more than 900 

 crossing 48°N as extreme. 

 Thus, 1991 was an extreme 

 year. 



HP's computer model 

 consists of one routine which 

 predicts the drift of each ice- 

 berg and another which pre- 

 dicts the deterioration of each. 



Page 6 



The drift prediction program 

 uses a historical current file 

 which is modified weekly us- 

 ing satellite-tracked ocean 

 drifting buoy data, thus taking 

 into account local, short-term, 

 current fluctuations. Murphy 

 and Anderson (1 985) describe 

 and evaluate the IIP drift 

 model. 



The IIP iceberg dete- 

 rioration program uses daily 

 sea surface temperature and 

 wave height information from 

 the U.S. Navy Fleet Numeri- 

 cal Oceanography Center 

 (FNOC) to predict the melt of 

 icebergs. Anderson (1983) 

 and Hanson (1987) describe 



the IIP deterioration model in 

 detail. It is the combined abil- 

 ity of the SLAR to detect ice- 

 bergs in all weather and MP's 

 computer models to estimate 

 iceberg drift and deterioration 

 which enables IIP to schedule 

 aerial iceberg surveys every 

 other week rather than every 

 week. 



Twelve satellite- 

 tracked ocean drifting buoys 

 were deployed to provide 

 operational data for HP's 

 iceberg drift model. Six 

 buoys were the standard size 

 drifting buoys IIP has been 

 deploying for sixteen years. 

 The other six were smaller 



