58 THE OCEAN 



very marked over the open ocean. In the 

 intertropical Atlantic the line of lowest 

 mean atmospheric pressure, towards which 

 the prevailing winds and their attendant 

 ocean currents flow, is situated at all seasons 

 to the north of the equator, and therefore the 

 surface currents of the South Atlantic, gener- 

 ated and maintained by the south-east 

 trades, cross the equator, conveying a high 

 temperature and a high salinity into a hemi- 

 sphere other than that in which they originate. 

 The remarkable salinity of the North Atlantic, 

 markedly higher than that of any other ocean, 

 has its explanation in the enormous overflow- 

 ings into it by the surface currents of the 

 South Atlantic, together with the equally 

 remarkable contributions to the salinity at 

 greater depths from the Mediterranean (see 

 Fig. 2). 



In the western portion of the Pacific, on the 

 other hand, the line of lowest atmospheric 

 pressure lies to the south of the equator for 

 eight months of the year, and accordingly 

 northerly winds with their accompanying 

 ocean currents cross the equator to lat. 15° S., 

 carrying a high salinity into the South Pacific. 

 Thus the conditions of salinity in the Atlantic 

 and Pacific are reversed, the highest salinity 

 being found to the north of the equator in the 

 Atlantic and to the south of it in the Pacific. 



