INSTRUMENTATION AND METHODS 



STD/DDL System 



The sampling instrument used on 301 stations 

 was a Plessey Environmental Systems, Model 

 9040, S/T/D Environmental Profiling System 

 (STD). For four stations where tlie STD sys- 

 tem was not operational, Nansen bottle casts with 

 deep sea reversing thermometers were taken. The 

 FM signals received from the STD were digitized 

 by a Sonycraft, Inc. (Chicago, Illinois) digital 

 data logger (DDL) and recorded on computer 

 compatible 7-channel magnetic tape by a Kennedy 

 Co. Incremental 1600R tape recorder (Altadena, 

 Calif.). For the general description of the DDL 

 recording and processing scheme for similar 

 equipment see Rosebrook (1971) ; the procedures 

 followed during the 1973 Ice Patrol were essen- 

 tially the same in form and content. The salient 

 differences may be found in Morgan, Bishop, and 

 Mulher (1976). 



STD Quality Control 



Nansen bottle salinity samples and deep sea 

 reversing thermometers were compared with the 

 STD values for temperature and salinity at 

 maximum cast depth for all stations taken in 

 water depth greater than 1000 m. The Nansen- 

 STD differences were plotted as a function of 

 time (i.e., for each station which had quality 

 control data) for the determination of temporal 

 variation. Values that showed small random 

 variations with time were averaged, and this av- 

 erage was applied as a constant correction to the 

 STD/DDL data from the surface to maximum 

 sampling depth. The quality control corrections 

 had the following absolute value ranges: tem- 

 perature, 0.00°C to 0.05°C and salinity, 0.04°/oo 

 to 0.08%„. 



The salinity of the quality control samples 

 was determined by an inductive laboratory- sali- 

 nometer. Conductivity ratios from the salinom- 



eter were converted to salinity utilizing the 

 method established in tlie International Oceano- 

 graphic Tables published by UNESCO and the 

 National Institute of Oceanography Great 

 Britain (1966). 



TABLE 1 



Summary of Oceanographic Stations 



Ice Patrol Cruise 1-73 : 

 Dates : 3-22 April 1973 



Sections: A-i, A3B MOD, A3A, A3, A2B, 



A2A and A2 MOD 



IIP Station Nos: 11186-11248 

 Total No. of Stations : 63 



Ice Patrol Cruise 2-73 : 



Dates : 8-28 May 1973 



Sections: A4 (Twice), A3C, A3B MOD, 

 A3A, A3 (Twice), and A2B 



IIP Station Nos: 11249-11329 

 Total No. of Stations : 81 



Ice Patrol Cruise 3-73 : 



Standard Ice Patrol Sections 



Dates : 13 June-14 July 1973 



Sections : A2 MOD, A2B, and A3 



IIP Station Nos: 11419-11449 



Total No. of Stations : 31 



Intensive Dynamic Surveys 



Dates: (I) 17-22 June, (II) 26-29 June, and 

 (III) 4-7 July 



IIP Station Nos: (I) 11330-11375, (II) 

 11376-11418, and (III) 

 11450-11490 



Total No. of Stations : 130 



