The Labrador Current Between Hamilton Inlet 

 and the Strait of Belle Isle 



July 1968 



Henrv S. Aii<ler§en ' 



INTRODUCTION 



From 17 July to 16 August 1968, the Coast 

 Guard Oceanographic Unit conducted a cruise 

 aboard the USCGC EVERGREEN (WAGO 

 295) to collect information about iceberg drift 

 and deterioration. This cruise was part of a 

 continuing Coast Guard program to monitor the 

 movements and deterioration of icebergs and 

 associated meteorological and oceanographic 

 conditions. The results of the oceanographic 

 observations are presented here; iceberg drift 

 and deterioration will be the subject of a future 

 publication. 



The USCGC EVERGREEN sailed from Bos- 

 ton, Massachusetts on 17 July 1968 en route to 

 the area of operation in the western Labrador 

 Sea between Hamilton Inlet and the Strait of 

 Belle Isle (fig. 1). A medium-size drydock ice- 

 berg was located on 22 July and tracked until 9 

 August 1968. The trajectory of the iceberg was 

 determined by using moored reference markers 

 and periodic radar plotting. Concurrent with the 

 tracking of the iceberg, direct current mea- 

 surements were obtained by parachute drogues. 

 A four-section hydrographic survey consisting 

 of 48 Nansen stations was conducted during 

 22-26 July to determine the dynamic topogra- 

 phy of the area. The USCGC EVERGREEN re- 

 turned to Boston on 16 August. 



Mr. Thomas C. Wolford, Oceanographer, 

 served as Field Party Chief for this cruise. He 

 was assisted by Lieutenant Commander Martin 

 J. Moynihan, USCG, and Ensign Henry S. An- 

 dersen, USCGR. Technical assistance was pro- 

 vided by Danny L. Allen, Aerographer's Mate 



' U.S. Coast Guard Oceanographic Unit, Washington, 

 D.C. 20390. Present address. Office of Environmental 

 Affairs, U.S. Department of State, Washington, D.C. 

 20520. 



Third Class; Michael L. Combs, Aerographer's 

 Mate Third Class; Kenneth L. Mitchell, Sonar- 

 man Third Class; and Mr. Ronald B. Lorenz, 

 student trainee. 



HATA COLLECTION AND PROCESSING 



Temperature data was acquired with paired 

 reversing thermometers mounted on Teflon- 

 lined Nansen bottles. Salinities were determined 

 on board with an inductive salinometer, using 

 tables prepared by UNESCO/NIO (UNESCO, 

 1966) for computing salinity from the mea- 

 sured conductivity ratios. Depths of sampling 

 were determined from the wire angle of the 

 cast and pairs of unprotected and protected 

 thermometers on selected Nansen bottles. Dy- 

 namic heights were computed on board using 

 a PDP-8/S computer. Dynamic heights in water 

 shallower than the reference level were com- 

 puted in a manner described by Kollmeyer 

 (1967). 



The data presented in the Tables of Ocean- 

 ographic Data are reproduced from a computer 

 listing from the National Oceanographic Data 

 Center (Cruise No. 31-1260). Anomalies of dy- 

 namic height in the listing were computed by 

 NODC, but all discussion of dynamic heights 

 in the text and related computations in this 

 report were based on dynamic heights com- 

 puted on board USCGC EVERGREEN or by 

 the Coast Guard Oceanographic Unit. 



INTERPRETATION OF RESULTS 



The Labrador Current comprises two distinct 

 bands — one over the continental shelf and the 

 other over the steepest part of the continental 

 slope (Smith, et al., 1937). Near Hamilton Inlet, 

 the inshore band over the continental shelf 

 possesses colder (<1°C), fresher (<33.5%o) wa- 



