OCEANOGRAPHY OF THE GRAND BANKS REGION OF NEWFOUNDLAND 



AND THE LABRADOR SEA IN 1970 



April-October 1970 



ROBERT ERWIN ETTLE' 



THOMAS CARLYLE WOLFORD' 



INTRODUCTION 



Four cruises were conducted on the Grand 

 Banks of Newfoundland and the Labrador Sea 

 during 1970 to study ocean currents that may 

 affect the drift of icebergs into the North At- 

 lantic shipping lanes (fig. 1). The study in- 

 cluded hydrographic surveys, direct current 

 measurements from vessels at anchor, and di- 

 rect current measurements from two taut-line 

 instrumented arrays set near 54-30N, 54-30W. 

 During the Ice Patrol season (March-July), ma- 

 rine environmental data were transmitted to 

 Commander, International Ice Patrol at New 

 York for use in predicting iceberg drift. 



Two of the cruises were conducted from Bos- 

 ton, Massachusetts aboard USCGC EVER- 

 GREEN (WAGO-295) during the Ice Patrol 

 season. The first cruise began on 1 April 1970 

 and ended on 27 April 1970. Since two port calls 

 were made at St. John's, Newfoundland (11-14 

 April and 18-20 April), the first cruise was di- 

 vided into three segments (fig. 2). The second 

 cruise began on 13 May 1970 and ended on 6 

 June 1970. One port call was made at St. John's, 

 Newfoundland (26-28 May), thus dividing the 

 second cruise into two segments (fig. 3). 



A post season cruise was conducted from Bos- 

 ton, Massachusetts aboard USCGC EVER- 

 GREEN (WAGO-295) from 15 July 1970 to 8 

 August 1970. In addition to the usual oceano- 

 graphic stations, two taut-line instrumented 

 arrays were set and recovered during this cruise 

 (fig. 4). 



A fall cruise was conducted from New York, 

 N.Y. aboard USCGC ROCKAWAY (WAGO- 

 377) from 30 September 1970 to 14 October 

 1970 (fig. 5). 



^ U. S. Coast Guard Oceanographic Unit, Bldg. 159-E, 

 Navy Yard Annex, Washington, D. C. 20390 



INSTRUMENTATION AND METHODS 

 STD Casts 



Data at 205 hydrographic stations were ob- 

 tained using a Bissett-Berman 9040 Salinity- 

 Temperature-Depth (STD) System. During the 

 Ice Patrol season, the STD analog frequencies 

 were digitized and recorded on IBM-compatible 

 magnetic tape using a Bissett-Berman 8114A 

 Digital Data Logger. With the exception of one 

 defective underwater unit and occasional elec- 

 tronic malfunctions of the deck unit, the system 

 performed well. 



Quality control samples were taken at each 

 station so that small corrections could be applied 

 to the STD data. To obtain quality control sam- 

 ples, a Niskin bottle with three deep sea re- 

 versing thermometers was placed 5 m. above the 

 underwater unit ; this was tripped when the 

 underwater unit was in an isohaline and iso- 

 thermal region. A temperature difference and a 

 salinity difference (quality control minus STD 

 observed) were calculated for each station ; 

 these were averaged over a group of stations to 

 obtain a correction for that group. The differ- 

 ences noted were fairly consistent, but some 

 significant changes in calibration occurred. Usu- 

 ally the changes in calibration could be related 

 to physical changes in the system. 



Nansen Casts 



Data at 29 hydrographic stations were ob- 

 tained using teflon-lined Nansen bottles fitted 

 with paired deep-sea reversing thermometers. 

 The conductivity ratios of the water samples 

 were determined using inductive laboratory sa- 

 linometers and were converted to salinity using 

 Tables la and lb of the International Oceano- 

 graphic Tables (1966). 



