700 Main Features of General Oceanic Circulation and their Physical Exploration 



vertically integrated transport vanishes at all points. This internal thermo-haline 

 circulation postulated by Stommel is in full accord with the deep-sea currents deduced 

 from the observations of the "Meteor expedition. The sinking of sub-Arctic water 

 masses in the Iceland-Greenland region (p. 684), the concentration of the North 

 Atlantic Deep Current close along the western side (p. 672), the rise in the sub- 

 Antarctic region of the water masses carried southwards (p. 687) and the sub- Antarctic 

 intermediate current flowing north (p. 679) are the principal constituents of this 

 internal thermo-haline circulation which derives its driving force from the density 

 differences between the sub-Arctic and the sub-Antarctic oceanic regions. The defi- 

 ciency of the Stommel representation of this internal circulation is that in the Atlantic 

 as in the other oceans, the Antarctic Bottom Current in which the Antarctic water after 

 sinking at the continental shelf into the deepest troughs flows northwards beneath the 

 sub-Arctic branch of the thermo-haline internal circulation (lower Atlantic Deep 

 Current), penetrates further into the North American Basin and after mixing with the 

 upper waters is carried south again in this current (see Figs. 323 and 331 ). 



In Fig. 335b, Stommel now shows separately a wind-driven circulation in the upper 

 layer corresponding to Fig. 334, except for the additional gyre just north of the equator 

 caused by the presence of an area of doldrums in the wind field there (p. 601). Both 



Fig. 335. A schematic interpretation of the circulation in the Atlantic Ocean constructed by 

 a superposition of an internal thermo-haline mode associated with a flow across a level 

 surface L at mid-depth (a) and a purely wind-driven circulation in the surface layers (b). 



The sum of these two is shown in Fig. (c). According to Stommel, 1957. 



Dashed arrows indicate portions of flow not given by elementary theory but evidently 



required by continuity and sketched in. 



