move the vessel with respect to the nearly motionless waters at the bottom 

 of the cast are considered o The winds throughout the cruise were generally 

 from the East tending to drive the vessel toward the iffest» Within the 

 North and South Equatorial Currents which flow also toward the West, the 

 vessel is carried westward with respect to the deep waters by both the 

 wind and the surface current and large wire angles result = In the counter- 

 current, the flow is directed toward the East but the wind, as before, toward 

 the West (during Cruise II) <, The resultant drift of the vessel with respect 

 to the deep water is small and small wire angles result. 



The wire angles are consistent with the existence of an eddy at the 

 northern boundary of the countercurrent on the eastern section. Large wire 

 angles were encountered through the southern lobe of the eddy where the 

 current was directed West. Relatively small wire angles were recorded at 

 the stations at 13°N and Li.°N located within the easterly flow of the 

 northern lobe of the eddy. The wind velocity did not alt-er appreciably 

 across the eddy„ The large wire angles at 11°N and 12°N may indicate that 

 the center of the eddy is incorrectly located on the dynamic height and 

 current profiles = 



Larger wire angles were encountered in the vicinity of the equator 

 than in the swiftest parts of the North Equatorial Current under comparable 

 wind conditions o Therefore 5 the South Equatorial Current was probably 

 flowing more swiftly than the North Equatorial Current o 



DISCUSSION 



Upwelling is occurring in the immediate vicinity of the equator on 

 both station lines » This is evidenced, for example, by the high phosphate 

 concentrations and low temperatures in the surface layer above the equator. 

 This upwelling results from a divergence of the pure wind drift current 

 along the equator. 



An abrupt change in surface temperature indicated on the thermograph 



traces and occurring over deepenings of the homogenous surface layer 



Indicate surface convergence and sinking. The regions of sinking do not 

 coincide with the countercurrent boundary. 



The other data indicate pronounced sinking motion at the surface 

 temperature "discontinuity". The surface water rich in phosphate, for 

 example, extends farther north on the eastern than on the western section, 

 the „6 ^ g at./l» isopleth being found at about 4.°N on the former and 

 between d°S and 3*^ on the latter. This suggests that upwelled water is 

 descending farther from the equator on the eastern than on the western 

 section, which is consistent with the positions of the convergence along 

 the two sections. This evidence alone would not be conclusive, however, 

 due to a possible difference of phytoplankton activity (and other factors) 

 at the two locations, 



A cellular circulation is indicated. On both sections, surface 

 divergence and upwelling is occurring at the equator and downward motion 

 at a convergence some distance to the North o At and near the sea surface, 

 water is moving from the equatorial divergence northward to the convergence 



