APPENDIX A 



OCEANOGRAPHIC CONDITIONS 1978 



LT C. R. WEIR 



DR. D. G. MOUNTAIN 



MR. R. M. HAYES 



U.S. Coast Guard Oceanographic Unit 



INTRODUCTION 



The International Ice Patrol (IIP) oceanographic 

 mission in 1978 consisted of two USCGC 

 EVERGREEN (WAGO 295) cruises to the Grand 

 Banks of Newfoundland from 30 March to 23 April 

 and 1-26 June 1978. The first cruise provided sea 

 current data from hydrographic surveys for the 

 computer prediction of iceberg drift by 

 Commander, International Ice Patrol. Two 

 satellite-tracked drogued buoys (BTT's) were 

 deployed in a cooperative project with the Woods 

 Hole Oceanographic Institution. The information 

 obtained was used to verify and improve opera- 

 tional iceberg drift by making Lagrangian 

 measurements of the sea current to compare with 

 estimates obtained by the hydrographic methods. 

 The second CGC EVERGREEN cruise was 

 dedicated to an on-going research project by the 

 Coast Guard Research and Development Center on 

 iceberg drift and deterioration. For the second 

 year a researcher from the University of 

 Washington, Seattle, Washington conducted an in- 

 vestigation examining the physical aspects of 

 iceberg deterioration. 



Two additional projects were accomplished 

 during the CGC EVERGREEN cruises. A 

 Geophysical Ocean Bottom Instrument (GOBI) 

 which measured pressure, water temperature, 

 water current, and gravity was deployed and 

 recovered for the Lamont-Doherty Geological 

 Observatory in the Laurentian Fan west of the Tail 

 of the Banks. During transit to and from the Grand 

 Banks on both cruises an XBT survey was made 

 across the mouth of the Gulf of Maine for the 

 National Marine Fisheries Service. 



OPERATIONAL DYNAMIC SURVEYS 



Methods and Materials— The dynamic surveys 

 were accomplished using a Plessey Environmental 

 Systems, Inc. Conductivity/Temperature/Depth 



(CTD), Model 9040, Environmental Profiling 

 System. The data were recorded and processed on 

 a Wang Laboratories, Inc. Model 600-14-TP 

 Programmable Calculator, a Wang Model 629 Dual 

 Tape Drive, and a Wang Counting Interface 

 (Electronics Lab USCG Station, Alexandria, 

 Virginia). 



Corrections were applied to the CTD system 

 temperature and salinity data from measurements 

 made by Nansen bottles with deep-sea reversing 

 thermometers at the bottom of each cast and from 

 surface bucket samples. Salinity was determined 

 with a Guildline Instruments, Inc. (Larchmont, 

 N.Y.) Model 8400 Autosal. The temperature 

 quality control value of -0.02°C was determined 

 from the average difference between the CTD and 

 the Nansen bottle data, and was applied as a 

 constant correction with depth. The salinity quality 

 control values were similarly determined from the 

 Nansen bottle data and the surface bucket 

 samples. Both the top and bottom salinity 

 correction values were -0.08°/oo- 



Standard Sections— IIP standard monitoring 

 sections A2C, A2B, and A2A were occupied 

 between 6-9 April. Sections AlB, AlC, and a 16 

 station special survey were completed between 

 13-17 April. Section A2 was begun, but due to a 

 hydraulic system casualty only 8 stations were 

 occupied. The special survey [see Table lA for 

 station locations] was arranged to delineate the 

 structure of the Labrador Current as it approached 

 Flemish Pass. 



The dynamic topography [Fig. lA] indicated that 

 the Labrador Current entered the survey area 

 flowing southeastward along the steep continental 

 slope. The current followed the bottom topography 

 turning south through Flemish Pass and along the 

 eastern edge of the Grand Banks similarly to the 

 average observed conditions [Scobie and Schultz, 

 1976]. The special survey indicated that the 



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