Oceanographic Observations on North Atlantic 

 Ocean Station ECHO 



November 1967— December 1968 



Alan D. Rosebrook^ 



INTRODUCTION 



Ocean Station ECHO (figs. 1 and 2) is one of 

 four stations in the North Atlantic Ocean 

 which have been regularly occupied by U.S. 

 Coast Guard cutters for the acquisition of me- 

 teorological and oceanographical data. The 

 Coast Guard Oceanographic Unit, in coopera- 

 tion with the U.S. Naval Oceanographic Office 

 (NAVOCEANO), first conducted oceanographic 

 observations at ECHO aboard CGC CASCO 

 in January-February 1963. These data were 

 published in U.S. Coast Guard Oceanographic 

 Report No. CG 373-2 (Morse and McGary, 

 1964). A long-term series of observations was 

 initiated by CGC YAKUTAT in September- 

 October 1966. The results of oceanographic ob- 

 servations taken from September 1966 through 

 October 1967 were presented in U.S. Coast 

 Guard Oceanographic Report No. CG 373-21 

 (Shuhy, 1969). 



DATA COLLECTION AND PROCESSING 



A total of 315 oceanographic stations was 

 taken by U.S. Coast Guard cutters at Ocean 

 Station ECHO during 14 patrols from 28 No- 

 vember 1967 to 5 December 1968. A summary 

 of oceanographic operations during the period 

 is presented as table 1. 



On 12 patrols, 226 daily Nansen casts were 

 made to sample 14 prescribed levels to 1,500 

 meters, weather and operational commitments 

 permitting. Initially, shallow cast observations 

 were desired at 0, 25, 50, 75, 100, 150, 200, 400, 

 500, 600, 800, 1,000, 1,250 and 1,500 m. During 



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

 Washington, D.C. 20390 



the June-July 1968 patrol by CGC HALF 

 MOON a Nansen bottle was placed at 300 m 

 and the 1,250 bottle was deleted. For the re- 

 mainder of the observational period the desired 

 depths were 0, 25, 50, 75. 100, 150, 200, 300, 

 400, 600, 800, 1,000, 1,250 and 1,500 m. In addi- 

 tion, once during each patrol at least one deep 

 cast to near bottom was attempted. The addi- 

 tional sampling depths prescribed for deep 

 casts were 2,000, 2,500, and 3,000 m, and 150 

 and 50 m off the bottom. Twenty deep casts 

 were taken successfully during the period. 



Each Nansen bottle was equipped with two 

 protected deep sea reversing thermometers. In 

 addition, five Nansen bottles used at 200 meters 

 and below were each fitted with an unprotected 

 thermometer so that thermometric depths 

 could be determined. Temperature data were 

 transmitted to the Coast Guard Oceanographic 

 Unit via radioteletype immediately after each 

 cast for real-time data processing and quality 

 control. In situ temperature values were com- 

 puted by a Digital Equipment Corp. PDP-5 

 computer to determine corrected temperatures 

 and thermometric depths. After the data were 

 quality controlled, they were relayed to Fleet 

 Weather Central, Norfolk, Va., and to Fleet 

 Numerical Weather Central, Monterey, Calif., 

 for use in forecasting synoptic oceanic condi- 

 tions. 



Water samples were drawn from the Nansen 

 bottles and the salinity of the samples was de- 

 termined using a shipboard inductive salino- 

 meter. The conductivity values obtained were 

 converted to salinity by use of the International 

 Oceanographic Tables published jointly by 

 UNESCO and the National Institute of Ocean- 



