TABLE 2 



Summary of Current Meter Deployments 



Current Meter Mooring No. 1 



Date/Time Established : 13 1530Z April 1973 

 Retrieved: 14 2215Z May 1973 



Position: 44°12.9'N Lat. 



48° 52.3' W Long. 



Depth to Bottom : 923 Meters 



Depth of Current Meter : 879 Meters 



Current Meter Model/Serial No. 

 EG&G 850/301 



Recording Rate : 15 Samples/15 Min. 



Record Length : 31.06 Days 



Current Meter Mooring No. 2 



Date/Time Established : 18 1632Z May 1973 

 Retrieved : 30 1300Z June 1973 



Position: 45°33.1'N Lat. 



48°15.9'W Long. 



Depth of Bottom : 987 Meters 



Depth of Current Meter: 951 Meters 



Current Meter Model/Serial No. 

 EG&G 850/300 



Recording Rate: 15 Samples/15 Min. 



Record Length : 42.84 Days 



Dynamic Calculations in Shallow Water 



The calculation of dynamic heights for stations 

 shallower than the 1000 decibar surface (which 

 for the Ice Patrol is considered approximately 

 equal to 1000 meters and is the reference level) 

 was performed in a manner similar to that of 

 Helland-Hansen (1934). Isosteric surfaces inter- 

 secting the ocean-sediment interface ai'e assumed 

 to extend horizontally inward such that the level 

 surfaces they repi'esent imply motionless water. 

 The method employed here, which is described 

 by KoUmeyer (1967), relies upon the extension 

 of temperature " and salinity contours into the 

 continental slope from which sigma-t is calculated 

 down to the Ice Patrol reference level. These 

 values combined with the sigma-t's from the 

 water column above are used in the determination 

 of dynamic height for stations shallower than 

 1000 meters on each section. 



Current Meter Data Processing 



The EG&G A850 current meter is a Savonius 

 rotor type of in situ recording current meter. 

 Signals from the rotor, vane follower, and com- 

 pass ai'e recorded discretely on a single track of 

 magnetic tape. The tape is a cartridge with two 

 tracks. When track A is filled the recorder auto- 

 matically shifts to track B to complete the re- 

 cording. Depending upon the sampling rate, this 

 current meter can be set to record for approxi- 

 mate periods of 81/2, 451/2, 86V2, and 156 days. 

 At the sampling rate of 15 samples every 15 

 minutes, which was used for the IIP-1973 cur- 

 rent meter moorings, the endurance was 861/^ 

 days. 



The current meter tapes were processed under 

 contract by the manufacturer who provided vec- 

 tor averaged north and east components over the 

 sampling period. Further analysis performed at 

 the Oceanographic Unit included a filtering pro- 

 gram (FILTR) that gave time series plots of the 

 north and east (or normal and tangential relative 

 to an arbitrarily selected direction) components 

 of velocity for data with frequencies higher than 

 0.5 cycles/hour, higher than 0.8 cycles/day, and 

 the periodic residuals resulting when one is sub- 

 tracted from the other. This program aids in 

 identification of the presence of any dominant 

 periodic trends in the current meter record. 

 Another program called HARMA was designed 

 to test the statistical significance of harmonic 

 periods selected for analysis from the filtering 

 program. 



These current meter arrays were subsurface, 

 taut-line moorings established near the ocean 

 bottom on the continental slope. The moorings 

 were designed using a computer program named 

 BUOY-M which was adapted for use by the 

 Oceanographic Unit from the program of 

 Berteaux and Chhabra (1973). The array com- 

 ponents and design were similar to those appear- 

 ing in the description of the intermediate mooring 

 in Heinmiller and Walden (1973). 



Navigation 



Loran A, Loran C, and UQN/4 fathometer, 

 and dead reckoning were the primary means of 

 navigation. The estimated range of accuracy of 

 navigational fixes was reported as 1.8-5.6 kil- 

 ometers. 



