HYDROLOGY OF THE SOUTH ATLANTIC 



225 



salinity scale has been made to read in a negative direction, the downward slope of the 

 curves towards the north thus showing a decrease in oxygen content, but an increase in 

 salinity. 



The two curves, which are approximately parallel, show maxima and minima which 

 correspond to the water which flows northwards from the region of mixing in different 

 seasons. Water which sinks from the Antarctic surface layer and flows northwards in 

 summer has a greater oxygen content and a lower salinity than water which sinks and 

 flows northwards in winter. There are not sufficient points on the curves to allow them 

 to be drawn exactly, but if they have any meaning at all their shape cannot diff^er very 



> 



O CALCULATED FROM OXYGEN MAXIMA 

 A CALCULATED FROM SALINITY MINIMA 

 \ CALCULATED FROM OXYGEN MINIMA 

 L CALCULATED FROM SALINITY MAXIMA 



Fig. 2j. The change in the speed of the Antarctic intermediate current towards the north. 



much from that shown. From the distance apart of the consecutive maxima or minima 

 the distance travelled by the water in one year can be calculated. 



In Fig. 23 the velocities calculated in this way have been plotted against latitude. 

 South of 20° S the velocities calculated from consecutive oxygen maxima and salinity 

 minima are greater than those calculated from the oxygen minima and salinity maxima. 

 This diff'erence would arise if the water which sinks in winter flows, at first, more quickly 

 than that which sinks in summer, and this might be the result of the greater density of 

 Antarctic surface water in winter, causing it to sink more quickly and take a more direct 

 path northwards. The difl^erence could also be explained if the water of minimum salinity 



