HI. SEA WATER TEMPERATURE MEASUREMENTS 



Murray H. Schefer 



A. INTRODUCTION 



The measurement of sea water temperature must be regarded as 

 the most fundamental in oceanography. It is also the ocean variable 

 about which the most data nave been collected. However, it reasonably 

 can be assumed that temperature measurements will continue to be 

 collected and will be studied intensively in an attempt to solve many 

 oceanographic problems. 



Although temperature measurements date back to the early days of 

 science, and the techniques and instruments for making these measure- 

 ments have reached a high degree of accuracy, sensitivity, and reliabil- 

 ity, special problems associated with the measurement of sea water 

 temperatures leave much to be desired, and there exists considerable 

 room for improvement. The measurement of sea water temperatures has 

 been complicated by several factors. The most important of these are: 



1. No standard data requirement can be stated. The specifications for 

 temperature measurements depend upon the use to which the data will be 

 applied or upon the specific problem under study. 



2. The sea must be considered as consisting of several layers in 

 each of which the thermal structure is generally different and the ther- 

 mal processes actually differ. Further, the time scale for these pro- 

 cesses varies considerably in the different layers, and the magnitudes 

 of the changes are of different orders. 



3. The concealment afforded by the oceans, which may be an advan- 

 tage in military operations, works against the scientist or surveyor 

 attempting to measure physical variables. Communication between the 

 sensing element and the observer, or a recorder, becomes complicated. 

 Also the effects of water under great pressure create many problems 

 of design. 



4. Equipment designed for use at sea must be rugged and reliable. 

 Ruggedness often is obtained at a cost of sensitivity. Reliability is 

 particularly important because too often the proper maintenance facil- 

 ities and personnel are not available aboard the survey ship. 



These, then, are the major problems associated with the measure- 

 ment of sea water temperatures. Other minor problems also exist that 



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