172 Thekmohaline Features 



in the ocean. Were the eddy diffusion coefficients independent of depth, the 

 depth of maximum w might nearly correspond to the bottom of the main 

 thermocUne. 



In summary, then, the Une of argument and interpretation of data pre- 

 sented here, although by no means conclusive, do suggest: (i) that the 

 interior of the subtropical and equatorial Atlantic Ocean is essentially wind- 

 driven, from a djmamical point of view; (ii) that in subpolar regions thermo- 

 haline processes are important; (iii) that in the western boundary currents, 

 effects due to the mass- conservation requirements imposed by both the 

 wind stress and the thermohaline process are important, even in subtropical 

 and equatorial latitudes; (iv) that the portion of the surface-layer western 

 current which is driven by wind stress is intimately connected -with Munk's 

 gyres, or a cell-like structure of wind currents; (v) that the thermohaUne 

 portion of the surface-layer western current flows from 40° S. latitude to 

 40° N. latitude almost unchanged in transport; (vi) that the deep circu- 

 lation at all latitudes is essentially thermohaline, but in subtropical and 

 equatorial latitudes is confined to a narrow western current of the (perhaps 

 inertial) boundary-layer type; and (vii) that, therefore, the mean vertical 

 flux of mass in the interior of subtropical regions at depths of 1000-2000 m. 

 is probably considerably less than that used in the theoretical rectangular 

 ocean (less than 10 cm. /day).* 



* Since the preparation of the manuscript for this book, I have written and 

 pubhshed a review article which supplements the ideas presented in this chapter: 

 'A Survey of Ocean Current Theory', Deep-Sea Research, 4 (1957): 149-184. Also, 

 I have attempted to make an analysis of hydrographic data in the North Atlantic 

 according to equation (27) under the title: 'On the Determination of the Depth of 

 No Meridional Motion', Deep-Sea Research, 3 (1956): 273-278. 



