Summary 



From 28 February to 27 August 1983, the In- 

 ternational Ice Patrol (IIP), an office of the U. S. 

 Coast Guard, conducted the International Ice 

 Patrol Service, which has been provided an- 

 nually since the sinking of the RMS TITANIC on 

 April 15, 1912. During past years, Coast Guard 

 ships and/or aircraft have patrolled the ship- 

 ping lanes off Newfoundland within the area 

 40°N - 52°N, 39°W - 57°W, detecting icebergs 

 and warning mariners of these hazards. During 

 the 1983 Ice Patrol season, Coast Guard 

 HC-130 aircraft deployed out of Gander, New- 

 foundland to search for icebergs in the Grand 

 Banks region of the North Atlantic. These air- 

 craft flew 73 ice reconnaissance sorties log- 

 ging over 427 flight hours. A total of 1352 

 icebergs were sighted south of 48°N latitude by 

 aircraft and ships transiting the area. This was 

 well above the annual average of 381. New 

 detection equipment, the AN/APS-135 Side 

 Looking Airborne Radar (SLAR), was introduc- 

 ed into Ice Patrol duty during the 1983 season. 

 It proved to be an excellent tool for the detec- 

 tion of both icebergs and sea ice, and provided 

 97 percent of the 1983 iceberg sightings. The 

 iceberg population was greater then normal 

 this year due, in part, to lower than normal 

 temperatures recorded throughout New- 

 foundland and Labrador which hindered the 

 melting process of the sea ice and extended 



its limits farther south. A combination of nor- 

 therly winds in the Labrador Sea combined with 

 generally southwesterly and westerly winds off 

 the Newfoundland coast also hindered the 

 breakup of the sea ice, which protected the 

 icebergs, allowing them to drift farther south 

 and in larger numbers. 



Oceanographic conditions were monitored 

 during the ice season through the use of seven 

 Tiros Oceanographic Drifters (TOD) which sup- 

 plied real time current information to the IIP. In 

 cooperation with the U. S. Coast Guard 

 Research and Development Center, three 

 icebergs were tracked via satellite using Tiros 

 Arctic Drifters (TAD) for periods of over two 

 months. The information provided by TOD and 

 TAD drifts (see Figures B-1 and B-2) was ex- 

 tremely useful in updating the iceberg drift 

 model (IBERG) which is utilized to update 

 iceberg positions in the Grand Banks region un- 

 til they either melt or break up. Another 

 oceanographic innovation during the 1983 Ice 

 Patrol season was the development and use of 

 a computer program to model iceberg 

 deterioration. This deterioration model was 

 conservatively used to elimimate icebergs from 

 the drift plot based upon wave, sea surface 

 temperature, and wind convective effects. 



