65 



does not suffer from over-temperature. Recording should probably continue 

 to be on a smoked glass slide although a waxed card might be satisfactory. 



i. Instruments Which Give Density, Salinity Or A T-S Diagram: As 

 long as we are interested in density and salinity there will always be a need for 

 an instrument that records or indicates those values continuously. Although the 

 basic components for such instruments have been used by many groups their as- 

 sembly into a completed instrument has not been done very often and the result- 

 ing instruments were expensive and complicated. Much more needs to be done 

 along these lines. 



DISCUSSION: E.G. LaFond 



With regard to Vine's statement of the temperature-measuring instru- 

 ments needed I would like to emphasize the depth range required for measure- 

 ments in the region of the Sofar sound channel. Since the axis varies in depth 

 from around 150 meters to 1100 meters, the instrument should be capable of 

 providing detailed temperature information down to 1200 or 1500 meters. Such 

 information is important to the Navy Electronics Laboratory in the study of long- 

 range transmission and sound intensities in the Sofar channel. The details from 

 the surface to the axis are more important than those below the axis; the latter 

 information can still be obtained by reversing thermometers. On long cruises 

 in the Pacific, standard depths are not used at present for sampling water and 

 temperature through the region of the sound-channel axis, instead, 50-meter 

 intervals are used. If a new BT were developed to cover this depth range, it is 

 believed that a temperature-salinity relation might be used in certain areas to 

 obtain the sound velocity by measuring temperature alone. 



Vine brought out the desirability of using an exponential depth scale to 

 emphasize the surface layers. This has been discussed before, and there ap- 

 pear to be two ways of modifying a BT to give this changing scale in depth. One 

 is to use tapered wire in making up the pressure coil, and the other is to make 

 the diameter of the coil turns successively greater. 



Vine also mentioned the processes in the sea in which we are interested. 

 The needed information may be boiled down to actual temperatures or changes 

 in temperature. More emphasis should be given instrunnents that measure 

 changes in temperature with time, depth, and distance. An instrument which 

 gives the difference, for example, between the temperature at the surface and at 

 any depth does not require as great a range as the universal instrument which 

 measures actual temperatures; it can thus achieve greater accuracy and is 

 easier to use. For most purposes, this difference in temperature is sufficent. 



The thermal sensing devices and recording methods will partly depend 

 upon the specific problems at hand. For example, temperature instruments 

 built and used at NEL for specific studies are a TPR -- temperature-profile- 

 recorder, a 16-channel temperature recorder, and a GTD -- conductivity-tem- 

 perature-depth indicator. 



The TPR was required to measure accurately the heat capacity in lakes, 

 since the BT was believed to get out of calibration occasionally, thus nullifying 

 the study. The TPR is a portable unit consisting of a thermistor sensing ele- 

 ment, 6-volt power supply, amplifier, and an Esterline Angus recorder. The 

 recorder is geared to the drum containing an electrical cable to which the bead 

 is fastened. When the bead is lowered in the water, the paper on the recorder 

 is moved accordingly. Depth is measured by the length of wire paid out; there- 

 fore, the instrument is confined to shallow depths and wire angles of zero de- 

 grees in order to record depth properly. This instrument was used on the Lake 

 Hefner water-loss investigation for fifteen months and then recalibrated with no 



