ANTARCTIC INTERMEDIATE WATER 71 



of crests and troughs which do not appear to be as regular as the similar curve in the 

 eastern part of the South Atlantic Ocean. South of the latitude of Durban (about 30 S) 

 the phosphate is greatest in or close to the salinity minimum of the intermediate current, 

 but north of this latitude the maximum content is found in the upper layers of the 

 warm deep water. In this respect the Antarctic intermediate current in the western 

 part of the South Indian Ocean is different from that in both the eastern and western 

 South Atlantic Ocean, where, north of the Rio Grande ridge in the west and, of the 

 latitude of approximately 46 S in the east, maximum phosphate always occurs in the 

 intermediate current 



The phosphate content of the intermediate current along section 7 across the South 

 Indian Ocean, between the ice-edge in 48 43'7' E and Fremantle, Australia, in May 1932, 

 may be seen in Plate XII. The phosphate content at the salinity minimum varied 

 between 108 mg. and 147 mg. but was in general of the order 120-125 m §-> tne high 

 value of 147 mg. being exceptional and occurring in the shallower water west of 

 Fremantle. The order of these values is slightly less than that of the stations south of 

 Cape Town. In the section across the South Indian Ocean the maximum content of 

 phosphate was not found in the Antarctic intermediate water but in the upper layers of 

 the warm deep water. This warm deep water is of complex origin, but the upper part 

 of the current contains a large proportion of North Indian Ocean deep water which 

 has a high phosphate content. The presence of North Indian deep water may be the 

 reason why the maximum phosphate content occurs in the deep water and not in the 

 intermediate water. 



South of Australia and Tasmania the content at the salinity minimum of the inter- 

 mediate current in June 1 93 2 along sections 9 and 1 o varied between 1 1 2 mg. and 1 1 8 mg. 

 and 121 mg. and 84 mg. respectively. These sections which were made between the ice- 

 edge in 130 07' E and Melbourne (Sts. 887-896), and between Melbourne and the ice- 

 edge in 1 54 26-2' E (Sts. 896-906), are shown in Plates XIV and XV. According to Deacon 

 (1937, p. 69) the intermediate current has a very small volume and a high salinity south 

 of Australia and Tasmania. He attributes this to the restriction placed on the northward 

 flow of the intermediate current by the land-mass of Australia and partly perhaps to the fact 

 that a large volume of highly saline water is forced to flow southwards in the subsurface 

 layer in order to flow south of Australia. The northward flow of Antarctic surface water 

 in the Antarctic zone itself may also be smaller owing to the relatively low latitude of 

 the Antarctic Continent in this part of the ocean. At none of the stations north of the 

 Antarctic convergence was there any indication of a temperature inversion. It was also 

 found that the phosphate content of the intermediate current south of Australia is 

 less than farther west as shown by sections 6 and 7 from Enderby Land to Guardafui 

 and Fremantle. The intermediate layer has less phosphate south of Australia than has 

 the warm deep water. 



South of the eastern half of the Tasman Sea, Deacon (1937, p. 69) notes that the 

 intermediate current has a slightly greater volume and is less saline than south of 

 Australia. In Plate XVI, which shows a section between the ice-edge in 158 24-5' E 



