544 EIGHTH PACIFIC SCIENCE CONGRESS 



responding to the East Australian Current, though actually this current 

 never develops so strongly because of many passages connecting the 

 Southern Pacific to the Indian Ocean through the numerous islands 

 and archipelagoes in the Australian-Asiatic Mediterranean. Had we 

 not these passages together with the Southern Antarctic Circumpolar 

 Ocean, we could have a much stronger western current in the South 

 Pacific Ocean than actually observed. 



It looks also rather strange that we do not have any strong west- 

 ward flow in the latitudes between 5° N and 2° S. Actually the north- 

 ern margin of the South Equatorial Current is in this zone. This comes 

 as the consequence that the Equatorial Counter Current appears in our 

 theoretical result much broader and much more diffuse than actually 

 observed. This is also the same in Munk's and Hidaka's results. The 

 theory of the Equatorial Counter Current has been attacked and ex- 

 plained by several authors (Montgomery and Palm^n, 1940, Neumann, 

 1947) in some other ways than ours. 



12. Evaluation of the Coefficient of Vertical Mixing 

 The streamlines in Figure 3 are drawn for an interval 

 A^ = 250 X lOio/D^ cm2/sec. 

 of the stream function. The velocity can be determined as the ratio 

 A^/Ax, where Ax is the actual distance between two consecutive stream- 

 lines. Because these diagrams are not drawn in a common scale for 

 the north-south and east-west directions, it would be rather laborous 

 to compute the magnitude of current velocity for all parts of the Pacific. 

 Still it will be easy to know it when the streamlines run in exactly north- 

 south or east-west directions. 



The values of the stream function at several points along the 33" N 

 parallel are computed as compiled in Table IV. Assuming the Pacific 

 Ocean is 10,000 kilometers across in its east-west direction, we obtained 

 the velocity of the Kuroshio at its swiftest zone, which is located approxi- 

 mately 55 km off the coast, to be 329 cm/sec, 219 cm/sec, 165 cm/sec, 

 and 110 cm/sec according as we assume D^ = 50 m, 75 m, 100 m and 

 150 m, respectively. 



Actual velocity of the Kuroshio has been estimated at approximately 

 3 to 5 knots, or about 150 to 250 cm /sec in its swiftest zone. From 

 Table IV we recognize that the computed velocity of the Kuroshio, 

 assuming for D^ a value between 50 m and 150 m, agrees with the ob- 

 served values fairly well. The previously determined values for D^ fall 

 mostly in this range also. This enables us to compute the values of 

 vertical coefficient of mixing from the formula (18). The above values 

 of Dj correspond to the values 188, 422, 750 and 1688 g/cm/sec of A^ 



