Model Evaluation 



No field evaluations of the deterioration 

 model were conducted this year, although two 

 were planned. Evaluations are planned for next 

 year. The evaluations will consist of 

 measurements of the environmental factors 

 and the response (deterioration) of the iceberg 

 to the observed parameters over a period of 

 several days. Attempts will be made to observe 

 several different sizes and types of icebergs. 



The results of ice reconnaissance flights by 

 IIP provided a preliminary evaluation of the 

 deterioration model. The model was evaluated 

 from the results of the flights using the follow- 

 ing criteria: 



- icebergs were identified as being re- 

 moved from the active berg list as a result of an 

 ice reconnaissance flight. 



- the melt percent predicted by the model 

 for the icebergs removed from the list was 

 tabulated (Table C-4). 



- icebergs that had been on plot less than 

 four days and removed were not considered for 

 inclusion in Table C-4. These bergs were 

 assumed to be improperly interpreted SLAR 

 targets when not resighted by a subsequent ice 

 reconnaissance flight. 



- icebergs that were in areas of no en- 

 vironmental data, i.e., areas close to the coast, 

 were not included in Table C-4. 



NOTE: Bergs whose melt percent exceeded 

 175% were being removed on a daily 

 basis including the days of ice recon- 

 naissance flights. 



The results shown in Table C-4 are encourag- 

 ing. Part of the 18% of the icebergs being 

 removed with a melt percent less than 66% can 

 be accounted for by improper sizing of SLAR 

 targets. Approximately 97% of all icebergs 

 entered into the model this year were SLAR 

 targets interpreted as icebergs. No attempt 

 was made to evaluate resighted berg sizes to 

 check if the new observed length corresponded 

 with the length predicted by the model because 

 the sizing information of SLAR iceberg targets 

 had not been verified. 



After the model has been thoroughly 

 evaluated, the model can be integrated into the 

 ICEPLOT program package where automatic 

 downgrading of iceberg sizes and removal of 

 melted icebergs will be possible. Before this 

 can be accomplished, several years of evalua- 

 tions will need to be completed. 



One other method used to evaluate the 

 deterioration model was to review iceberg 

 deterioration described in the literature and 

 compare these with the deterioration predicted 

 by the model. Two bases for this comparison 

 were found (Robe, et al., 1977 and Kollemeyer, 

 et al. 1966). In both instances the actual 

 deterioration of the iceberg was faster than 

 that predicted by the deterioration model. This 

 is a positive result since the model was de- 

 signed to be conservative. The iceberg 

 deterioration model, in the meantime, can be 

 used as another tool in disseminating, as ac- 

 curately as possible, iceberg information to the 

 maritime community. 



Table C-4 



Month 



Less than 66% 



Between 66% and 100% Greater than 100% 



February 



March 



April 



May 



June 



July 



August 



5 

 25 

 19 

 24 



5 

 14 



3 



8 

 32 

 28 

 70 

 17 

 39 



5 



15 

 15 

 23 

 58 

 14 

 91 

 6 



Total 



Totals 

 Percent 



95 



18% 



199 



39% 



222 



43% 



516 



Model percent melt of icebergs removed from the active berg file as a result of IIP ice recon- 

 naissance flights during the 1983 season. 



72 



