WATER MASSES AND CURRENTS OF THE OCEANS 163 



are similar to the corresponding Arctic Intermediate Waters, but the 

 Subantarctic Water is distinctly different in character from the Antarctic 

 Intermediate Water. 



The regions of formation of the intermediate, deep, and bottom waters 

 are shown in the chart in fig. 40, and the characteristic temperature and 

 salinity values of these water masses can be read off from the diagrams 

 in the lower part of the figure. The deep water of the different oceans 

 will be discussed more fully when dealing with the deep-water circulation 

 of the oceans. 



Currents of the North Atlantic Ocean 



The North Equatorial Current. The system of currents in the 

 North Atlantic (chart 4) is dominated by the North Equatorial Current 

 to the south and by the Gulf Stream system to the north. The North 

 Equatorial Current flows from east to west in the trade-wind region and is 

 fed by the southeasterly currents off the west coast of North Africa. 

 Corresponding to flow from the northwest, water of relatively high 

 density and low temperature is found off the African coast, as is evident 

 from the charts of surface temperatures (charts 1 and 2). The tempera- 

 ture close to the coast is also lowered by upwelling from moderate depths, 

 owing to the action of prevailing northwesterly winds, but this upwelling 

 does not exercise as wide-spread an influence as does the corresponding 

 upwelling off the coasts of southwest Africa, or, particularly, as that off 

 the west coasts of North and South America. 



In the western part of the North Atlantic Ocean the North Equatorial 

 Current joins a branch of the South Equatorial Current which has crossed 

 the Equator and which, according to fig. 40, p. 159, carries character- 

 istically different water masses. Thus, the part of the North Equatorial 

 Current that continues into the Caribbean Sea carries water which is 

 mixed with water of South Atlantic origin, whereas the northern branch 

 of the North Equatorial Current, which flows along the northern side of 

 the Great Antilles as the Antilles Current, carries water that is identical 

 with that of the Sargasso Sea. 



The Gulf Stream System. The North Equatorial Current termi- 

 nates in the current through the Yucatan Channel and the Antilles 

 Current, and the continuation of these currents represents the beginning 

 of the Gulf Stream system, which dominates the circulation of a great 

 part of the North Atlantic Ocean. In accordance with the nomenclature 

 of Iselin the term /'Gulf Stream system" is used to include the whole 

 northward and eastward flow beginning at the Straits of Florida and 

 including the various branches and whirls that are found in the eastern 

 North Atlantic and that can be traced back to the region south of the 

 Newfoundland Banks. This system can be subdivided into the following 

 parts : 



