Main Features of General Oceanic Circulation and their Physical Exploration 695 





tZ*^ 



QOO^O'' 



>o\ dWe' 



rqerice 



Equatorial counter current 

 Equotoriol divergence 



South 



equo/o 



Current 





i^e/o 



'^^-e^ 



Fig. 33 1. Meridional vertical cross-section from pole to pole through the Atlantic Ocean. 

 Schematic representation of the tropospheric and stratospheric oceanic circulation. 

 — ocean bottom, , boundary layer between tropo- and strato- 

 sphere from Northern polar front to Southern polar front. Salinity distribution: 

 Fw>n>1 , >36-0%o, B>i?l , 36-0-34-9?4, ^^^ , 34-9-34-6%„, 1^^^ , <34-6%o, 

 — >-, current-form spreading,-'- ,,', convection-like spreading and convection-like sinking, 



exaggeration about 1 :400. 



stand out particularly in this diagram. In the north the effects are more sub-arctic due 

 to the bottom topography, but their influence on the stratospheric water movements is 

 still extremely important. 



If we ask for the driving forces of the stratospheric oceanic circulation it must be 

 stated that only differences in the thermo-haline structure of the water masses can be 

 the cause for these circulations, and these contrasts can only be maintained by atmos- 

 pheric influences affecting the regions north of the oceanic polar fronts and are so 

 regenerated again and again. Thermodynamic machines of this type can only do work 

 when the compressions of the medium set into motion occur at a lower pressure 

 than the expansions (see p. 489 and following pages). The water in the upper circulation 

 branch is set in motion from a region of smaller to a region of greater density, and in 



