Ocean Currents in a Non-homogeneous Ocean 



495 





 400 

 800 

 1200 

 1600 

 2000 



dyn.cm 

 -12 -8 -4 +4 +8 





-4 +4 +8 



dyn.cm 



+ 12 



Fig. 226. Schematic example for fixing the reference-level by means of the vertical distribu- 

 tion of the dynamic depth of the standard pressures of two neighbouring stations. (The 

 lower "displaced" scale of the abscissa only has its correct position, if the reference-level is 

 assumed in the layer denoted by the vertical arrow; a position of the reference-level at the 

 dashed arrow, for example, would be quite improbable.) 



while the dynamic structure of the other layers will be divided up in a rather unintelli- 

 gible way. It is more plausible to suppose that this more prominent layer should be 

 motionless, or almost motionless, so that the reference-level should lie within it. 

 Such a layer with obviously low velocities is apparently characteristic not only for the 

 pair of stations under consideration, but is to some extent depending on the pressure 

 field of the entire oceanic region under consideration. The reliability of this method is 

 increased if the individual reference depths, determined from a large number of station 

 pairs, can be combined to give a closed system representing a definite topography of 

 the reference-level. 



To illustrate the method the difference-curves for the dynamic depths are shown in 

 Fig. 227 for a meridionally distributed set of stations in the Atlantic ; for each curve the 

 vertical extent for which a layer of no motion or only weak motion is most probable, 



dyn cm 



1 B 12 16 20 



dyn cm 



Fig. 227. Fixing of the dynamic reference-level for a series of meridionally distributed 

 stations in the Atlantic Ocean. 



