estimated 1 753 icebergs drifted south of 48°N; 

 whereas, during 1992 876 icebergs drifted 

 south of 48°N. Based on the historic iceberg 

 counts of its entire 79 year history, IIP classi- 

 fies the severity of the ice seasons. Ice years 

 with fewer than 300 icebergs crossing 48°N 

 are defined 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 

 (Alfultis, 1987). 1993 was an extreme year 

 when compared to the entire history in addi- 

 tion, it is well above average for the recent 

 years in which SLAR has been used. Appen- 

 dix D presents a detailed description of HP's 

 reconnaissance techniques since 1960. 



Table 2 

 Number of Icebergs South of 48°N 



^ 



Era 

 Average 



927 1753 



^ 



The 1 993 season was the first year that 

 IIP used its iceberg Data Management and 

 Prediction System (DMPS). This system, which 

 is nearly identical to the iceBerg Analysis and 

 Prediction System (BAPS) used at the Cana- 

 dian Ice Centre, Ottawa, combines an iceberg 

 drift model with a deterioration model. The 

 model uses wind, ocean current data, and 

 iceberg size data to predict the movement and 

 deterioration of all icebergs entered into DMPS. 

 Appendix F presents an examination of the 

 impact of the DMPS on MP's correlation of 

 most recent sighting data with the predicted 

 movement of previously sighted icebergs. The 

 drift prediction model uses a historical current 

 data base which is modified weekly using 

 satellite-tracked ocean drifting buoy data, thus 

 taking into account local, short-term, current 

 fluctuations. Murphy and Anderson (1985) 

 described and evaluated the drift model. 



The iceberg deterioration model 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 (1 987) described the IIP deterioration 

 model in detail. 



Eight satellite-tracked ocean drifting 

 buoys were deployed to provide current data 

 for MP's iceberg drift model during the 1993 

 season. All were World Ocean Circulation 

 Experiment (WOCE) drifters. All buoys were 

 equipped with temperature sensors. One of 

 the buoys had a drogue at 15 meters and the 

 remainder were drogued at 50 meters. Drift 

 data from the buoys are discussed in the IIP 

 1993 Drifting Buoy Atlas, which is available 

 upon request. Appendix E discusses in detail 

 recent improvements in the drifting buoy pro- 

 gram. 



llPconductedanoceanographiccruise 

 aboard USCGC BITTERSWEET (WLB 389) 



