ICEBERG DISTRIBUTION IN BAFFIN BAY AND THE LABRADOR SEA AS DETERMINED 

 FROM PRESEASON ICE PATROL FLIGHTS BY THE UNITED STATES COAST GUARD 



By C. W. Morgan, U.S. Coast Guard 



Abstract 



The purpose and background of preseason Ice 

 Patrol flights by the U.S. Coast Guard is dis- 

 cussed. The technique of preseason aerial iceberg 

 reconnaissance is described. The results of the 

 flights are analyzed in terms of average and ob- 

 served icebergs per two square degrees for Baffin 

 Bay in summer and fall, for southwestern Baffin 

 Bay and the Labrador coast in early December 

 and January, and for the Labrador coast in Feb- 

 ruary. Deviations from the average are analyzed 

 for the fall Baffin Bay data. 



Data from the preseason flights show that pat- 

 terns of iceberg concentration are generally the 

 same from year to year, although there are usual- 

 ly changes in the overall level of concentration. 

 Patterns of iceberg concentration in Baffin Bay 

 indicate that the movement of icebergs directly 

 across Baffin Bay may be as important as the 

 route north through Melville Bay. Analysis of 

 the dissipation of a large positive iceberg anom- 

 aly off Cape York during the period 1966-69 

 indicates that it takes about 3 years for a heavy 

 accumulation of icebergs in northern Baffin Baj' 

 to clear out. Analysis of the February data indi- 

 cates that there is a fair positive correlation 

 (0.61) between iceberg concentrations observed 

 on the February flight and the severity of the 

 iceberg season on the Grand Banks. There is also 

 fair positive correlation (0.77) between the south- 

 ernmost extent of icebergs observed on the Feb- 

 ruary flight and the date when icebei-gs arri\'e 

 on the Grand Banks. 



Introduction 



The icebergs which drift south in the spring 

 of each year to threaten shipping in the area of 

 the Grand Banks of Newfoundland come mostly 

 from the glaciers which terminate in Baffin Bay. 

 The questions of exactly how icebergs drift from 



their source glaciers to the Grand Banks, how 

 long it takes, and how icebergs are distributed 

 in Baffin Bay and along the Labrador coast have 

 been of interest to the U.S. Coast Guard in man- 

 aging the International Ice Patrol and to others, 

 for many years. 



The interest of the U.S. Coast Guard concern- 

 ing icebergs in Baffin Bay and along the Labra- 

 dor coast giew from a desire to understand better 

 the entire iceberg problem. Following the R.]\I.S. 

 Titanic disaster of 1912 the Coast Guard was 

 assigned the duty of operating the Ice Patrol. It 

 was readily apparent that an understanding of 

 the natural factors controlling the drift and de- 

 terioration of icebergs would be of great value 

 in intelligentlj' operating the patrol. Information 

 on iceberg distributions in Baffin Bay and along 

 the Labrador coast is an important part of under- 

 standing the total iceberg problem. It has long 

 been suspected that the number and distribution 

 of icebergs available to drift south from Baffin 

 Bay could be a signiflcant factor in determining 

 the severity of iceberg conditions on the Grand 

 Banks during a given ice season. 



The fii'st attempt to collect information system- 

 atically on iceberg distributions north of the 

 Giand Banks was in the summer of 1914 when 

 the LT.S. Revenue Cutter Seneca, sailed as far 

 north as southern Labrador "to observe the origin 

 of the ice wliich annually appears on the Banks 

 of Newfoundland, and to investigate the agencies 

 by which it is transported from the North." 

 (Johnson, 1915). The next expedition took place 

 14 years later when the U.S. Coast Guard Cutter 

 Ma)'ion was dispatched as far north as Disko 

 Island for oceanography and ice observation 

 under the command of Lieutenant Commander 

 (later Rear Admiral) IMward H. "Iceberg" 

 Smith (Smith, 1931). Later cruises and expedi- 

 tions were made by the ships indicated below. 



