1 96 WATER MASSES AND CURRENTS OF THE OCEANS 



only persistent features are that the countercurrent is in most months well 

 developed between lat. 5° and 6°N and that the greater volume of water 

 transported by the countercurrent is deflected to the north and northwest, 

 where a strong current prevails off the coast of Central America. Another 

 but weaker and much more irregular branch turns to the south. In the 

 Gulf of Panama, large seasonal changes occur that are associated with 

 the change in the prevailing wind direction. 



Currents of the North Pacific Ocean 



The North Equatorial Current. There is considerable similarity 

 between certain currents of the North Pacific and of the North Atlantic 

 Oceans, but there are also striking differences that are due mainly to the 

 occurrence of large quantities of Subarctic Water in the North Pacific, as 

 contrasted to the small amounts of that type in the North Atlantic. The 

 Subarctic Water of the Pacific and the currents that carry Subarctic 

 Water are present in the northern and eastern areas, and similarity to the 

 North Atlantic is therefore found in the southern and western part 

 of the ocean, where the North Equatorial Currents correspond to each 

 other and where the Kuroshio corresponds to the Florida Current and the 

 Gulf Stream. 



The North Equatorial Current of the Pacific Ocean runs from east to 

 west, increasing in volume transport because new water masses join the 

 current from the north. The very beginning of the North Equatorial 

 Current is found where the waters of the countercurrent turn to the north 

 off Central America. To these water masses are later added the waters 

 of the California Current, which have attained a relatively higher tem- 

 perature and salinity, owing to heating and evaporation, and which have 

 been mixed with waters of the tropical region. Between the American 

 coast and the Hawaiian Islands, Eastern North Pacific Water is added 

 to the equatorial flow, and to the west of the Hawaiian Islands a consider- 

 able addition of Western North Pacific Water appears to take place. No 

 details are known as to the character of the current, and only a few 

 isolated computations of velocities can be made. These indicate that one 

 has to deal with a broad and relatively deep current within which the 

 maximum velocities are mostly less than 20 cm/sec. A vertical trans- 

 verse circulation is present with ascending motion at the northern 

 boundary of the countercurrent and with descending motion at the 

 Tropical Convergence. The waters therefore move in a spiral-like 

 fashion, and the motion is probably highly complicated owing to the great 

 distance between the regions of major divergence and convergence and 

 to the presence of local divergences and convergences. 



It is probable that before reaching the western boundary of the ocean 

 the Equatorial Current begins to branch off mainly to the north, but also 

 partly to the south, feeding the countercurrent. To the east of the 



