546 EIGHTH PACIFIC SCIENCE CONGRESS 



respectively. These are, of course, values consistent with the results 

 derived from many other different sources. (Sverdrup, et al, 1942). 



13. Subsurface Circulation 

 Figures 4, 5, 6, 7, and 8 show the horizontal distribution of stream- 

 lines in the level i/gZ),, D„ H/gZ),, 2D^, and 3D, below the sea surface, 

 respectively. All give patterns similar to the surface circulation shown 

 in Figure 3. We have western currents and a boundary vortex attached 

 to each gyre. The only difference noticed is a general subsidence of 

 the motion as we go down into deeper layers. Still, we see that the 

 intensity of motion is only reduced to as low as half that of the sea sur- 

 face even in the layer 31);,. Figure 9 shows the comparison of the cur- 

 rent velocity profiles along the 33° N parallel at several levels to that 

 on the surface of the sea assuming D^ = 75 m. The maximum speeds 

 are seen at about 55 kilometers off the western boundary. Although 

 the Japanese Islands are not disposed parallel to a meridian, the above 

 result agrees with the observed profiles of this mighty current quite satis- 

 factorily. Another result of particular interest is that, at a distance 

 larger than about 150 km, there is a flow to the south with much larger 

 velocity than in upper layers. This counter current reaches a maxi- 

 mum speed of 20 to 30 cm/s at about 200 km off the western coast, 

 despite the practically motionless upper layers. Figure 10 gives the 

 comparison of the zonal distribution of EW-components along a meri- 

 dian 24 degrees of longitude to the east off the western boundary. In 

 this longitude it is expected that the influence of the western boundary 

 nearly vanishes and the actual flow pattern of the Pacific circulation 

 is disposed mostly as a zonal current system. The velocities of the 

 current in these diagrams were computed assuming D., = 75 meters. 

 For computing the velocities when the value of D^ is different, we have 

 only to multiply these figures by lh/D.„ where D^ is expressed in meters. 

 If we assume, however, that the value D, = 75 m is consistent, we have 

 for the maximum surface velocities of North Pacific Current, North 

 Equatorial Current, Equatorial Counter Current, South Equatorial 

 CuiTcnt, and Antarctic Circumpolar Current 22, 19, 8, 23 and 23 cm/sec 

 respectively. They are reduced to 18, 16, 8, 18 and 18 cm/sec respec- 

 tively at a level i/gZ), and to 11, 9, 8, 9 and 10 respectively at 2D,. The 

 Equatorial Counter Current remains nearly unaltered in its speed in 

 all depths compared above. 



14. Vertical Variation of the Currents 

 The most important objective of the present research is to get a 

 certain idea about the vertical structure of the wind-driven circulation 

 in the Pacific Ocean. Tliis will be, of course, impossible to obtain from 



