and the wind curl. It is evident that the vertical velocity com- 

 ponent must be taken into account in order to explain the steady- 

 state circulation in a bounded ocean. Otherwise, the result that 

 the permanent ocean currents are only related to the rotational 

 component of the wind stress field over the ocean would indicate 

 that the currents must vanish were the wind stress field irro- 

 tational. 



Most of the important assumptions of the previous models are 

 concerned with the lower boundary of the wind-induced circulation 

 system, or the "depth" of the currents, and with the concept of 

 lateral and vertical eddy viscosity, especially with the concept 

 of isotropic lateral mass exchange. 



With the attempt to explain some of the observed detail flow 

 patterns in the Gulf Stream north-northwest of the Azores, in the 

 California current and the Norwegian current by taking non-iso- 

 tropic lateral mass exchange into account, the author's attention 

 was called to some probable relationships between the vertical 

 density gradient, the depth of the current, the variation of lati- 

 tude while the current flows in meridional direction, and the "age" 

 of the current, that is, the time when a wind of a certain velocity 

 starts to blow over an ocean originally at rest. 



The varying depth of the wind generated oceanic circulation 

 is the first fact with which we are concerned, and which has been 

 neglected in the previous models even in the case of a steady 

 oceanic circulation. This depth depends on the density strati- 

 fication of the ocean, the "age" of the current, and possibly on 

 internal friction (lateral and vertical). At this point some 

 difficulties arose, so that we are facing the problems of the g ross 



