178 DISCOVERY REPORTS 



the flow of the intermediate current is principally in the layer of minimum salinity, and that its flow 

 in the layer of minimum temperature is probably much affected by turbulent mixing with the under- 

 lying deep water. 



A well-marked layer of minimum salinity was encountered at all stations off the continental shelf 

 on both of the surveys. Table 7 shows the depths and observed salinities in the layer of minimum 

 salinity. Wiist developed a method for studying the mixing path of a water type from its T-S relation- 

 ships. Initially the water type is plotted as a point on a T-S diagram. As it mixes with adjacent layers 



SALINITY '/o» 



34 00 



-J I L 



3500 



35 50 



Fig. 32. Temperature -salinity relationships of the water layers between 100 m. and the salinity minimum of the Antarctic 

 intermediate water. The heavy line shows the relationship in the core of the Antarctic intermediate water from its source 

 (left) to its northern limit (right), after Wiist, 1935. The thin line is the line characteristic of South Atlantic central water 

 (Sverdrup, 1946). 



the point moves along a line, until eventually its characteristic, say a salinity minimum, disappears 

 (Fig. 32). Thus one can follow the water type from its beginning until it is completely obliterated by 

 mixing with other waters. This method is known as the ' Kernschichte methode ' — the core method. 

 Applying it to the intermediate water one finds that in the core of the antarctic intermediate layer the 

 effect of vertical mixing has altered the T-S relationship from the original water type (T = 2-2° C, 

 S = 33-80 %o) to a value of T = 4-7° C, S = 34-4 % off South-west Africa (Fig. 32). As the salinity 



Table 7. Salinity minima in the antarctic intermediate layer 



Station 



WS976 

 WS 977 

 WS978 

 WS986 

 WS996 

 WS 997 

 WS 1056 

 WS 1070 

 WS 1080 

 WS 1081 



WS 1 102 



Salinity minimum 



(%o) 



34-5° 

 34-34 

 34-45 

 34-38 

 34-34 

 34-3 1 

 34-33 

 34-42 

 34-38 

 34-29 

 34-3 1 



Depth 

 (m.) 



700 



820 



600' 



800 



600 



570 



600 



600, 820 



780 



990 



630 



The figures show the minimum values of salinity recorded at 'William Scoresby' stations, 



and the depths of the observations. 



