improved the drift predictions of tfie International Ice 

 Patrol's IBERG model. Ttie model's predictive ability was 

 evaluated by comparison of re-sighted iceberg data and 

 Viras found to be within approximately 5.8 ( + /- 2.5) nautical 

 miles per day. With the addition of real-time current infor- 

 mation from the TOD tracks, we hope to see this error circle 

 decrease. 



Evaluation of this year's data and data from previous 

 years (1979-81) suggests that topographic steering (Shuhy, 

 1981) is a very Important process that cannot be ignored in 

 the Ice Patrol area. The data suggests that objects drifting 

 south in the Labrador Current will follow one of three paths 

 as they near Flemish Cap. If the object is between the 

 200-and 500-meter contours, then it will most likely con- 

 tinue south through the Pass in the mainstream of the cur- 

 rent. If the object is between the 1000- and 2000-meter con- 

 tours it will most likely turn to the northeast and then pass 

 around the Cap. If the object is outside the 2000-meter con- 



tour then it will most likely spin off to the east and then to 

 the northeast as it passes north of Flemish Cap. From here, 

 it will enter the eastward North Atlantic Drift removing It 

 completely from the Ice Patrol area. 



We have found that TODs provide us accurate current in- 

 formation and much timelier measurements at a reduced 

 cost compared to shipborne hydrographic surveys. With 

 the increase in satellite technology, we hope to increase 

 the accuracy of our model by adding more real-time en- 

 vironmental Information. During the upcoming 1983 Ice 

 Patrol season we will be testing another addition to our 

 model, an iceberg deterioration program. This program will 

 depend on inputs of SST, significant wave heights and 

 period, and the relative speed of icebergs with respect to 

 the current. LT lain ANDERSON, USCG, of the Atlantic Area 

 Marine Sciences Branch developed this program. With its 

 addition, we hope to more accurately predict the change in 

 an iceberg's size, which will affect the error of our drift 

 prediction. 



References 



Mooney, K. A. (1978). "A Method for Manually Calculating 

 the Local Wind Current". U.S. Coast Guard 

 Oceanographic Unit Technical Report 78-2. 



Murray, J. J. (1979). "Oceanographic Conditions", Report of 

 the International Ice Patrol Services in the North Atlantic 

 Ocean, Season of 1979. Coast Guard 188-34, Bulletin No. 

 65. 



Shuhy, J. L. (1981). "Oceanographic Conditions on the 

 Grand Banks During the 1981 International Ice Patrol 

 Season", Report of the International Ice Patrol Service in 

 the North Atlantic Ocean, Season of 1981. Coast Guard 

 188-36, Bulletin No. 66. 



Table B-1 



* TOD #2598's parachute failed to open upon deployment from the aircraft and the ensuing impact caused this TOD to 

 cease functioning immediately. 



B-2 



