Salinity of the Ocean, its Variation in Oceanic Space and in Time 



155 



salinity variations to be found; these are supplemented by a chart showing mean 

 annual amplitudes. Over the major part of the open ocean surface away from coastal 

 areas the annual range in salinity in middle latitudes is less than 0-5%o, usually less 

 than 0-25%o. A zone with more than 0-5%o and a core with more than \%o and oc- 

 casionally over l-5%o extends right across the Atlantic from South America to Africa 

 between 5° and 15° N. and includes the area of the equatorial counter current. There 

 is a further region with values greater than 0-5%o and several cores about l%o in the 

 Gulf Stream region until the south-east of the Newfoundland banks. Otherv^dse the 

 maxima of annual variation are found in coastal areas especially off the mouths of the 

 larger rivers (Amazon, La Plata, and the inner part of the Gulf of Guinea) with large 

 seasonal variations in fresh-water inflow or in polar areas with seasonal melting of the 



Table 70. Diurnal salinity variation 



Minimum; f Maximum 



Fig. 64. Diurnal salinity variation. Above: the mean of five "Meteor" anchor stations 



between 21 ° S. and 4° N. in the Atlantic Ocean. Below: the mean for three days at the Altair 



anchor station (44-5° N., 34" W.). 



