WATER MASSES AND CURRENTS OF THE OCEANS 195 



Within the countercurrent, descending motion takes place at the 

 southern boundary and ascending motion at the northern boundary, and 

 between the Equator and the countercurrent descending motion takes 

 place at the boundary of the countercurrent and ascending motion at the 

 Equator. Thus, two cells appear with divergence at the northern limit 

 of the countercurrent and at the Equator, and with a convergence at the 

 southern boundary of the countercurrent. This system, which appears 

 so clearly in the Carnegie section, is quite similar to the one that Defant, 

 on the basis of theoretical considerations, has derived for the counter- 

 current in the Atlantic Ocean (fig. 50, p. 184). 



Owing to the convergence and the divergences the water does not flow 

 due east or due west, but superimposed upon the major current there is 

 a spiral motion which within the countercurrent carries water from the 

 northern to the southern boundary at the surface and carries water in 

 the opposite direction at depths between 50 and 200 m. Similarly, 

 within the Equatorial Current between the Equator and the counter- 

 current the surface water moves from the Equator toward the counter- 

 current, but at depths between 100 and 150 m the water moves in the 

 opposite direction. To the north of the countercurrent and to the south 

 of the Equator, subsurface water moves toward the divergences at the sur- 

 face, and this water must originate from the regions of the Tropical 

 Convergences, which lie outside the section under consideration. Accord- 

 ing to Defant's estimate the maximum north-south component of velocity 

 is not more than one fifth of the east-west component. 



From the above discussion it is evident that the equatorial divergence 

 is not related to the proximity of land and that the conditions met with 

 in the Galapagos area and to the west do not simply represent a con- 

 tinuation of the conditions off the coast of Peru, as had been previously 

 assumed. 



The character of the countercurrent is complicated both at the origin 

 of the current between New Guinea and the Philippines and at the termi- 

 nation against the American coast. Schott has shown that large seasonal 

 changes take place to the north of New Guinea, where from June to 

 August the South Equatorial Current follows the north coast of New 

 Guinea and converges sharply with the North Equatorial Current in about 

 lat. 5°N, where the countercurrent begins, whereas from December to 

 February part of the North Equatorial Current bends completely around 

 off the southern islands of the Philippines, sending one branch toward 

 the southeast along the north coast of New Guinea, and another branch, 

 the countercurrent, toward the east. 



Similarly, great seasonal variations occur in the Central American 

 region, as is evident from the data presented on the U. S. Hydrographic 

 Pilot Charts, but in this region the picture is complicated by numerous 

 eddies whose locations appear to vary from one year to another. The 



