1. Routine instruments 



a. Standard bathythermograph 



For synoptic description of the thermal structure, large vol- 

 umes of data taken by nonscientific personnel are required. For this 

 purpose the standard BT is considered to be the most valuable instru- 

 ment that will be available for many years. Mechanically, the standard 

 BT is an excellent instrument. It is rugged, simple to operate, and 

 relatively inexpensive. Its potential accuracy is believed to be limited 

 only by the ability to read the trace against the grid (about ± 0.2°F 

 and ±1 percent of the full depth scale). This potential accuracy usually 

 is not reached because existing observational and calibration proce- 

 dures are not adequate. 



Studies of mechanical and procedural inaccuracies are being made 

 and are expected to result in a modified standard operating procedure 

 that will include a simple technique for a partial field calibration. 

 Required improvements for future BT instrumentation include built-in 

 calibration devices, increased depth range to 3,000 feet and a winch to 

 handle the additional wire involved, increased resolutional capability 

 of the slide, and a design for rectilinear grid coordinates to allow 

 automatic and semi-automatic processing and analog-to- digital conver- 

 sion of the temperature trace. 



It is recommended that the Hydrographic Office support further 

 development of the present bathythermograph with a view toward 

 achieving the improvements listed above. The requirement for a built- 

 in calibration device should be given first priority The Hydrographic 

 Office should continue investigation and evaluation of the problem. 



b. Hull-mounted temperature probe 



A great need exists for a bow-mounted surface temperature 

 probe on all ships reporting marine -weather and especially ships 

 participating in the oceanographic surveillance net. The resulting 

 data would replace the injection temperatures which are nearly al- 

 ways erroneous. The instrument should record remotely on the bridge 

 where time and position data may be annotated on the record in the 

 same way as they are on depth records. These temperature records 

 should be filed with the Hydrographic Office for possible subsequent 

 analysis, but most important, reliable radio reports of these sea 

 surface temperatures would contribute immensely to a better under- 

 standing of transient horizontal temperature distributions in the 



III -7 



