Oceanographic Observations 



North Atlantic Standard Monitoring Sections 



A5, A6, and A7, 1967-69 



Bv 



Robert Quincy Robe^ 



INTRODUCTION 



Standard Monitoring Sections A5, A6, and A7 

 lie in the western North Atlantic with their near- 

 shore ends in the shallow waters off the eastern 

 coast of the United States and their offshore ends 

 in deep water off the continental slope (fig. 1). 

 Section A5 extends from the continental shelf at 

 the eastern extremity of the Gulf of Maine to a 

 location approximately 275 miles northwest of 

 Bermuda. Section A6 runs southeast from Cape 

 Hatteras to 31°55'N and thence due east to Ber- 

 muda. Section AT is located on the parallel of 

 latitude 28°3.5'N running from a point off the 

 east Florida coast near Cape Kennedy, 425 

 miles due east. All three sections are designed to 

 cross the Gulf Stream system completely and 

 nearly perpendicularly. On 1 May 1972 these 

 sections were shortened by eliminating several 

 stations on the seaward end of the sections. 



As a first step toward understanding large 

 scale oceanic processes, U.S. Coast Guard 

 Ocean Station Vessels have occupied standard 

 sections in the North Atlantic since 1964. The 

 goal was to occupy sections A5. A6, and A7 

 quarterly. Ocean Station Vessels occupied these 

 sections on their return from Ocean Stations 

 BRAVO, CHARLIE, DELTA, and ECHO. 

 U.S. Coast Guard oceanographic ships ROCK- 

 AWAY and EVERGREEN occupied A5, A6, and 

 A7 as required. 



'U.S. Coast Guard Oceanographic t'nil, Washington, D.C. 20390 



DATA ACQUISITION AND PROCESSING 



Temperature data were acquired either with 

 paired reversing thermometers on Nansen bottles 

 or with a salinity-temperature-depth sensor sys- 

 tem (STD). The acquisition and processing of 

 temperature data from the reversing thermome- 

 ters generally followed the procedures specified 

 by U.S. Naval Hydrographic Office Publication 

 No. 607 (1955) and La Fond (1951). A PDP-5 or 

 PDP-8 computer was used for thermometer cor- 

 rections. STD temperature values were read from 

 an analog trace and corrected using reversing 

 thermometer values at the surface and bottom of 

 the cast for quality control. 



Salinity values were either determined from a 

 sample collected with teflon-lined Nansen bot- 

 tles and analyzed on board with inductive 

 salinometers or were read from an analog STD 

 trace, quality controlled by a salinity sample 

 from the surface and bottom of the cast. The 

 salinometers were calibrated with standard 

 (Copenhagen) water at least once per 30 sam- 

 ples. The conductivity values obtained were 

 converted to salinity by use of the International 

 Oceanographic Tables published jointly by 

 UNESCO and the National Institute of Oceanog- 

 raphy of Great Britain (1966). 



Sampling depths on Nansen casts were de- 

 termined with paired protected and unprotected 



1 



