Introduction 



Ocean Station BRAVO is located in the 

 North Atlantic Ocean at latitude 56°30' N. and 

 longitude 51°00' W. This station has been 

 monitored since January 1964. The first report 

 on the data collected at this ocean station cov- 

 ers the period of time January-April 1964, in- 

 cluding 46 Oceanographic Stations. The results 

 of this initial study are published in the Coast 

 Guard Oceanographic Report No. CG 373-7. 

 The second report, Coast Guard Oceanographic 

 Report No. CG 373-9, covered the period Au- 

 gust 1964-August 1965 during which time 73 

 oceanographic stations were taken at BRAVO. 

 The Coast Guard Oceanographic Report No. 

 CG 373-14 was the third in the series. This re- 

 port covered the period October 1965-Septem- 

 ber 1966 during which time 68 stations were 

 taken. 



This is the fourth report of the series and 

 covers the period October 1966-October 1967 

 during which time 125 oceanographic stations 

 were occupied. Data from the previous reports 

 are used to show the variations of temperature 

 and salinity for the past four years. 



Procedures 



During the period October 1966-October 

 1967 U.S. Coast Guard cutters were instructed 

 to take daily Nansen casts, weather and oper- 

 ating conditions permitting, while occupying 

 Ocean Station BRAVO. These casts were made 

 at 14 prescribed levels to 1500 meters. They 

 were also instructed to take at least one deep 

 cast as close to the bottom as practicable dur- 

 ing each patrol. On shallow casts the pre- 

 scribed sample depths were as follows: 0, 25, 

 50, 100, 150, 200, 250, 300, 400, 500, 600, 800, 

 1000, and 1500, meters. The prescribed depths 

 for the deep casts were 2000, 2500, 3000, and 

 150 and 50 meters off of the bottom. 



Two deep-sea reversing thermometers were 

 attached to each Nansen bottle. Between the 

 depths of 200 and 1500 meters an unprotected 

 thermometer was also used on four to five 



Nansen bottles to determine thermometric 

 depths. Depths which were determined ther- 

 mometrically are preceded by a "T" in the sta- 

 tion data, Tables I-IX. Field observations 

 were returned to the Coast Guard Oceano- 

 graphic Unit (CGOU) for reduction to "in 

 situ" temperature and determination of sample 

 depths. The procedures used in recording and 

 processing of the thermometric data are simi- 

 lar to those in the U.S.N.H.O. Pub. No. 

 607(1955) and Lafond (1951). The CGOU used 

 a Digital Equipment Corporation PDP-5 com- 

 puter to determine corrected temperatures for 

 the protected thermometers and determine the 

 thermometric depth of the unprotected ther- 

 mometers. 



Water samples were drawn from each Nan- 

 sen bottle and stored in citrate bottles for 

 salinity determinations. The salinity was de- 

 termined aboard ship using induction salino- 

 meters. Duplicate samples were drawn from the 

 top and bottom bottles of each cast and deliver- 

 ed to CGOU for quality control purposes when 

 the vessel returned to port. 



The processed temperature and salinity data 

 were recorded on form NHO/NODC-3167/1 

 (1-61), "Physical and Chemical Data form for 

 Oceanographic Stations" and delivered to the 

 National Oceanographic Data Center (NODC). 

 The interpolated temperatures and salinities 

 for standard depths, sigma-t, specific volume 

 anomalies (AD), and sound velocities were 

 computed by NODC and are presented in Ta- 

 bles I-IX. 



The Ocean Station vessels are normally re- 

 quired to maintain station within a ten-mile 

 square grid. The actual positions of the sta- 

 tions taken on each patrol are shown in figures 

 3-11. Forty of the 125 stations taken were out- 

 side of the ten-mile grid. 



The USCGC DUANE occupied 11 oceano- 

 graphic stations during the period 8-28 Octo- 

 ber 1966. Nine of the casts were to depths 

 ranging from 1273 to 1775 meters. One station 



