D was assumed to be constant. Therefore, the term responsible 

 for the "westward intensification", j^ jtr- > which contains the 

 variation of the Coriolis parameter with latitude (planetary vor- 

 ticity) was not cancelled out by the variation of the depth D with 

 latitude (topographic vorticity, according to Ekman's terminology). 



It seems unlikely that the east -west asymmetry of the gross 

 features of the oceanic circulation is caused by the variation of 

 the Coriolis parameter with latitude, but since there is an inten- 

 sification of ocean currents along the east coasts of North America 

 and Eastern Asia, this particular flow pattern requires another 

 explanation. This may also answer the question why an analogous 

 intensification of the subtropical gyre (Munk, 1950) is not found 

 in the Southern Hemisphere. 



It seems more likely that the ocean reacts to the planetary 

 v orticit y effect in such a way that it rather tends to adjust its 

 l evel of no motion for the wind driven circulation than to displace 

 t he whole gyre with relatively h igh current velocities to the west . 

 Whether or not this adjustment is complete is a question which still 

 has to be answered. 



It may be added that the relationship as stated in equation (13) 

 does not say anything about "cause and effect". The zero layer may 

 be the result of the current system, and probably it is to some 

 degree in the gross features and even in the details. However, 

 several other external and internal forces and factors, besides those 

 taken into account, are involved in the mutual relationships between 

 the oceanic circulation and the stratification. Some of these 

 factors are the large scale heat gain and loss through the sea sur- 

 face and evaporation, precipitation, and lateral and vertical mixing 



16 



