SOME CHARACTERISTICS OF SEA WATER STRUCTURE 647 



However, in most cases, there is considerable short-term fluctuation in 

 the fine structure and even in the dimensions of the boundary and up- 

 per zones. Examination of several series of hourly bathythermograph 

 observations, such as illustrated in Figure G, indicated that this fine 

 structure was transient, that the thickness and depth of the major zones 

 varied with time, but the principal characteristics such as the gradient 

 and range of values of the properties in the major zones were constant. 

 It is evident that the fine detail is not significant, within the limits of 

 the usual serial observation, and that the structure is adequately de- 

 fined by the simplest interpretation. 



From these considerations it may be concluded that a zone is a 

 layer of water in the sea where the gradient of a property is a single 

 linear function of the logarithm of depth, -within small limits of error. 



Structure of Ifidependent Properties 



Figure 7 illustrates the temperature, salinity, density (o-^^ ), and 

 dissolved oxygen structure from a single serial observation, which is 

 representative of the general experience. The structure ^vith respect 

 to each property is readily interpreted by the log-plot technicjue but 

 the structure do not coincide. 



TABLE III 



Summary of Experience of Fitting the Log-Plot to Serial 



oceanographic observations in the deep zones of the 



Northeast Pacific Ocean 



Sufficient examinations, as shoAvn in Table III, have been made 

 to prove that the log-plot fits the density structure as ^\'ell or better than 

 it fits the temperature or salinity structvue, but as shown in Figure 7, 

 the structure is a combination of these. The distribution of dissolved 

 oxygen is also found to be logarithmic, but the structure is distinct from 

 these others. Similar conclusions Avere indicated by the cursory exam- 

 ination of some dissolved phosphate data. 



Evidently the structure -^vith respect to each independent property 

 is unique. The limits of the temperature zones are different from the 

 limits of the salinity zones, and the dissolved oxygen structure is dif- 

 ferent from both. This is reasonable since the advection and dissipation 

 of these properties are independent functions. 



