58 



While the BT is not a particularly complicated instrument its reliability and 

 surprisingly accuracy have vastly increased our knowledge and appreciation of 

 the complexity of the thermal structure of the ocean. 



WHAT SHOULD WE MEASURE? 



This section is aimed at showing what a large range of thermal measur- 

 ing problems exist in the ocean and what a large variety of instruments will be 

 required to solve them. It is also aimed at making us look more critically at 

 the measurements which we take. 



Figure 2 is an attempt to show that one can find thermal problems in the 

 ocean of almost any linear dimension in depth one chooses. This figure indi- 

 cates the various full scale depth ranges 

 one might use for different problems. 

 Figure 2 illustrates several features: 

 a. No matter what depth scale one 



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chooses to work over there are 

 other smaller scale phenomena 

 and problems. There are also 

 very apt to be larger scale 

 phenomena. 



b. An individual instrument will only 

 cover a farily small range of 

 depths, usually this is from full 

 scale to 1% or possibly l/lO% of 

 full scale. Because of this limi- 

 tation many problems must be 

 tackled with two or more types of 

 instruments. 



c. Attention is called to the logarith- 

 mic chart because it infers that 

 the surface (zero depth) cannot be 

 attained. The writer used to be 

 worried about this aspect of loga- 

 rithmic presentation but he is now 

 convinced that this is an experi- 

 mental reality with which we must 

 live. The finite size of thermal 

 probes, the characteristic infra 

 red radiation methods, and the 

 general oscillatory motion of the 

 water surface make the true sur- 

 face temperature something about which we can speculate but can probably 

 never measure. This may seem like a trivial point but to study evaporation 

 problems one may well want to know what is happening in the top few 

 microns. 



d. The fact that oceanography involves problems covering a full scale depth 

 range of over 100, 000, 000 is something we should bear in mind when con- 

 sidering future research problems. 



Any division into categories must necessarily be somewhat arbitrary but 

 the writer also suggests the following breakdown of operating depth as the ones 

 which usually affect pressure case design, length of cables, etc. 



Fig. 2. Depth Scale 



1. Above the water 



Marine meteorology, 

 or the vapor phase of 

 oceanography 



