Anchor Stations 



Direct current measurements were made at 

 two anchor stations (See fig. 2 for location.) in 

 about 100 m. of water. A Hydro Products Model 

 502 in-situ Current and Temperature Recording 

 System was lowered on the hydrographic wire 

 at each station. Observations were made at 

 depths of 25, 50, and 75 m. for 30 minutes each. 



Taut-Line Instrumented Arrays 



Many of the problems inherent in designing 

 a taut-line moored buoy system were avoided by 

 adopting and modifying a successful design de- 

 veloped by Woods Hole Oceanographic Institu- 

 tion (Berteaux and Walden, 1969). Two taut- 

 line instrumented arrays were moored in 216 m. 

 of water on 21 July 1970 and were recovered on 

 4 August 1970 (See fig. 4 for location.). A total 

 of five current meters was placed on the two 

 arrays (fig. 6). Two photographically recording 

 current meters were placed on the first array 

 (54-30N, 54-32W) at the 38 and 81 m. levels, 

 while three magnetic tape recording current 

 meters were placed at the 37, 81, and 124 m. 

 levels on the second array (54-29N, 54-30W). 

 The two shallowest current meters on each ar- 

 ray were to determine the current milieu that 

 would act on a representative medium size ice- 

 berg. 



The site chosen for the arrays was picked 

 because it satisfied the following conditions : the 

 bottom was nearly horizontal, the water depth 

 was not substantially greater than 200 m., cur- 

 rent speeds did not greatly exceed one knot, 

 and the location was near standard section Al. 

 These criteria were followed in site selection to 

 provide the greatest probability of the project's 

 success. 



The data from all of the current meters were 

 processed by Woods Hole Oceanographic Insti- 

 tution (WHOI) under a Department of Trans- 

 portation contract (DOT-CG-10618-A). The 

 tapes or the films were read, and the unedited 

 data were placed on a computer-compatible mag- 

 netic tape. The original tapes were then put in 

 a permanent storage file at WHOI and are avail- 

 able for reexamination at any time. The original 

 films were returned to Coast Guard Oceano- 

 graphic Unit for retention. The computer- 

 compatible magnetic tape was then reformatted 

 to a standard WHOI binary format, and the 



data were displayed in several ways to evaluate 

 the quality of the recording. Experienced per- 

 sonnel then edited the displays and eliminated 

 erroneous data points. The data from the mag- 

 netic tape recording current meters were of ex- 

 tremely high quality, and little editing was 

 required. The data from the photographically 

 recording current meters required some diag- 

 nostic work prior to further processing. There 

 were three distinct problem areas with the pho- 

 tographically recording current meters: 



• Slow clock (meter J-237) 



• Sticky compass (meter J-138) 



• Forbidden zones (near and 12.5 cm. /sec) 

 in the speed records (both meters). 



During data processing at WHOI, corrective ac- 

 tion was taken to alleviate each of these prob- 

 lems observed in the photographically recorded 

 data. However, the speed values for meter J-138 

 (81m. level) still remained unreahstic. The data 

 from J-138 were not analyzed further, except 

 for the construction of plots of current direc- 

 tion vs. time. 



The result of the editing procedure was a time 

 series of vectors representing the observed cur- 

 rent with one vector produced for each record 

 on the film or tape. This vector time series was 

 then processed to produce one-hour vector aver- 

 ages which were used in all the ensuing pro- 

 cessing. The following graphic presentations 

 were prepared for each current meter record : 



• Current direction and speed vs. time 



• North-south and east-west components of 

 velocity vs. time 



• Cross-spectral estimates including both co- 

 herence and phase (not done for the pho- 

 tographically recording current meters) 



• Progressive vector diagrams 



• Kinetic energy density spectral estimates 



• Power density spectral estimates. 



Meteorological Observations 



Meteorological observations of wet and dry 

 bulb temperatures, wind, sea and swell, baro- 

 metric pressure, visibility, and present weather 

 were made at each hydrographic station and 

 each anchor station. 



Data Reduction 



A PDP-8/S computer (Digital Equipment 

 Corporation) was used to correct reversing ther- 



