520 EIGHTH PACIFIC SCIENCE CONGRESS 



dinate system, except in the magnitude of the mass transport. These 

 facts show us that we have only to treat the circulation driven by a 

 zonal wind system. 



An earlier paper (Hidaka 1950) contained a theory of ocean circu- 

 lation using the current velocity in place of the mass transport. The 

 analysis was complex because the vertical variation of the movement 

 of water had to be taken into account. The result was nonetheless 

 quite ridiculous; no perceptible concentration of the streamlines towards 

 the west coast could be found. The explanation for this result was 

 that the approximation to the mass transport was inadequate for its 

 east-west variation. Thus, the solution smoothed out the western cur- 

 rents and boundary vortices which were apparent in Munk's paper. 



The mass transport method which has been adopted by Defant 

 (1941), Stockmann (1945-46), Sverdrup( 1947), Reid (1948), Munk (1950, 

 1951) and recently by Walter Hansen (1952) is surely eminent, especially 

 in the point that it enables us to reduce the analysis to two dimensions, 

 and makes the mathematical procedure very simple. Moreover, it is 

 not necessary for us to consider the vertical variation of density and 

 vertical coefficient of eddy viscosity. These authors have indeed con- 

 tributed greatly to the solution of many important problems on the 

 oceanic circulation by this method. The author himself also employed 

 this method several times in discussing the problems in this direction. 

 However, it is impossible for this method to show how the wind-driven 

 circulation varies in a vertical direction. Neumann also expressed re- 

 cently (1952) his opinion for the necessity of the dynamical treatment 

 of ocean currents as a three-dimensional problem. 



All of these circumstances lead one to recompute the general circu- 

 lation of the Pacific Ocean under the modified conditions and assump- 

 tions. The present investigation is one of the results of the author's 

 efforts in this direction. We here treat the general circulation of the 

 water in a square ocean comparable in size to the entire Pacific Ocean 

 Basin. Spherical coordinates, which were used in a preceding paper 

 (Hidaka 1951), are not used here partly in order to avoid mathematical 

 difficulties. But the more basic reason is that the two systems of co- 

 ordinates did not give any important difference between Munk's and 

 the author's results except for the magnitude of mass transport. The 

 value of the lateral mixing coefficient is taken 3.08 X 10^ c.g.s., a value 

 consistent with the research of former investigators. The wind system 

 is considered zonal, because this assumption is far simpler for the sub- 

 sequent analysis, and also because there has been found no' essential 

 difference between the results obtained under the assumptions of zonal 

 and anticyclonic wind distributions. Of course, the variation of the 



