INTRODUCTION 



Ocean Station DELTA (44°00' N., 41°00' W.) 

 is located near the edge of the North Atlantic 

 Drift (an extension of the Gulf Stream system) 

 which is usually described as having a multiple- 

 current structure and, therefore, the oceanograph- 

 ic conditions at DELTA would be expected to be 

 complex. The U.S. Coast Guard Oceanographic 

 I"'^nit, in cooperation with the U.S. Naval Oceano- 

 graphic Office (NAVOCEANO), first investi- 

 gated the oceanographic en^^ronment at DELTA 

 aboard tlie USCGC CASCO in March-April 1963 

 with the i^urpose of initiating a long term series 

 of observations. These data were published in the 

 U.S. Coast Guard Oceanographic Eeport No. 3, 

 CG 373-3 (McGary and Morse, 1964). Analysis 

 of these data indicated that there were several 

 distinct water masses present in the near vicinity 

 of Ocean Station DELTA and that there were 

 large horizontal gradients in the temperature and 

 salinity distributions. 



NAVOCEANO conducted five 3-week cruises 

 at Ocean Station DELTA between June 1962 and 

 July 1963 to determine the vertical and horizontal 

 variability in water properties in the immediate 

 area of DELTA. Analysis of these data revealed 

 that due to the proximity of DELTA to the North 

 Atlantic Current, time sampling is similar to space 

 sampling (Corton. 1967). 



The water masses at DELTA were described as : 

 (1) The surface mass of North Atlantic Drift (of 

 Gulf Stream origin) which varied in thickness 

 from 47.5 to 780 meters; (•2) intermediate water 

 masses, a cold water mass of subarctic origin and 

 Mediterranean water which advects into the area, 

 and (3) deep water masses, North Atlantic deep 

 water and Newfoundland basin water. 



The U.S. Coast Guard was unable to begin its 

 time-series study at DELTA immediately in 1963 

 due to a shortage of deep sea reversing thermome- 

 ters. The long term series of observations was 

 initiated in July 1966 by the USCGC ESCA- 

 NABA. The oceanographic sampling program 

 consisted of daily Nansen bottle casts to 1,500 

 meters on alternate 3-week patrols. This program 

 was expected to reveal large scale or seasonal 

 changes in the water properties at DELTA. This 

 report contains the data from 136 oceanographic 

 stations at DELTA taken during the period from 

 July 1966 to August 1967 by eight U.S. Coast 

 Guard cutters. They were the USCGC ESCA- 

 NABA, 1.5 July-2 August 1966; USCGC CAMP- 



BELL, 27 August-16 September 1966; USCGC 

 HUMBOLDT, 12 October-2 November 1966; 

 USCGC CHINCOTEAGUE, 26 November-17 

 December 1966; USCGC DUANE, 10-31 January 

 1967; USCGC CASCO, 20 March-11 April 1967; 

 USCGC OWASCO, 26 May-17 June 1967; and 

 USCGC SPENCER, 11 July-3 August 1967. 



PROCEDURES 



The sampling program at Ocean Station 

 DELTA consisted of daily Nansen bottle casts to 

 a depth of 1,500 meters when weather and other 

 operations permitted. The Ocean Station vessels 

 are normally required to make their oljservations 

 within a 10-mile square grid centered on the nomi- 

 nal Ocean Station (44°00' N., 41°00' W. at 

 DELTA). The location of DELTA in relation to 

 the other Ocean Stations in the world is shown 

 in figure 1. 



For the daily casts the desired sampling depths 

 were surface, 25, 50, 100, 150, 200, 250, .300, 400, 

 500, 600, 800, 1,000, 1,250, and 1,500 meters. For 

 the deep casts the desired depths were 2,000, 2,500, 

 3,000, 3,500, and 4,000 meters plus 150 and 50 

 meters above the bottom as indicated by the ves- 

 sel's echo-sounder. Serial observations of tempera- 

 ture and salinity were made at each station. 



A pair of protected deep sea reversing thermom- 

 eters were fitted into each Nansen bottle and, in 

 addition, four or five bottles below 200 meters had 

 an unprotected thermometer paired with the two 

 protected ones for the thermometric determina- 

 tion of the sampling depths. Depths which were 

 determined thermometrically are preceded by a 

 "T" in the Oceanographic tables. Field observa- 

 tions of temperature were transmitted via radio 

 teletype to the Coast Guard Oceanogi-aphic Unit 

 immediately after the oceanographic station for 

 real-time data processing and quality control. The 

 reductions to In situ temperatures were accom- 

 plished with the use of a Digital Equipment Cor- 

 poration PDP-5 computer. The processed data 

 were then transmitted within 18 hours of observa- 

 tion to the Fleet Numerical Weather Facility, 

 Monterey, Calif., for use in oceanographic 

 forecasting. 



"Water samples for the determination of salinity 

 were dra^^^l from each Nansen bottle and stored in 

 citrate bottles. The salinity content of each sam- 

 ple was determined aboard ship using inductive 

 salinometers. The results of the salinity determi- 

 nations were transmitted to the Coast Guard 



