as the 40° parallel . The Red Sec, nevertheless, is much less important in 

 supplying the Indian Ocean with water than is the Mediterranean the Atlantic 

 because the Red Sea supply is variable with the season and from year to year. 



However, unlike the Atlantic, in the Indian Ocean there is apporently no 

 deep, northward-flowing return current, or if such exists, it is of much less 

 importance and is sluggish. Also, the intermediate water is characterized by 

 its low oxygen content which is lowest in the north and which increases toward 

 the south, apparently gaining oxygen by mixture with other water (Sverdrup, 

 Johnson, and Fleming, 1942). 



Much of the earlier data collected in the Indian Ocean were either 

 inaccurate or insufficiently refined for use in determining water mass move- 

 ments . Thus, Mailer's sections based on work prior to 1929 (Mailer, 1929) 

 are not generally recognized today. The work of Clowes and Deacon (1935) 

 and Deacon (1937) were perhaps the earliest attempts at an accurate picture of 

 circulation in the Indian Ocean. Later, the published reports of Tchernia, 

 Lacombe, and LeFloch (1951) and of Tchernia, Lacombe, and Guibout (1958) 

 have made use of more recent data. Circulation of the deep water in the 

 western Indian Ocean was reported upon in a recent paper by Le Pichon (1960) 

 In which the "core method" together with geostrophic computations were used. 

 Le Pichon reported a deep current setting to the north which was deflected 

 and weakened by the complex system of ridges. Deacon's (1937) idea of the 

 mixing of Atlantic deep water with Indian Ocean water south of Africa was 

 also confirmed in Le Pichon 's paper. 



Surface and near-surface currents form a rather complex pattern which 

 varies with the season and from year to year. In general, an easterly current 

 sets between Africa and Australia, and during the summer this bends and joins 

 a current coming from the Pacific south of Australia. In winter this current 

 continues on along the southern Australian Coast. The southern part of the 

 Indian Ocean has a large anticyclonic system of currents which, again. Is 

 similar to that found in the Atlantic, but the currents in the Indian Ocean are 

 much more variable. North of 20° S., a westerly setting, equatorial current 

 flows. This current is strongest in winter because It is reinforced with water from 

 the Pacific coming along north of Australia; however, in summer, the water north 

 of Australia flows into the Pacific. The Agulhas Current, which sets south along 

 the African coast, is reinforced by part of the South Equatorial Current which 

 turns south. Most of this strong current returns to the Indian Ocean south of Africa, 

 but some, apparently, turns westward and flows into the Atlantic. Probably some 

 Antarctic Intermediate water flows northward In the southern portion of the Indian 

 Ocean. Deep water from the Atlantic comes Into the Indian Ocean around Africa. 

 There Is, evidently, some intermixing of Intermediate water with deep water and 

 bottom water. Red Sea water can be traced as far south as the Antarctic (Thomsen, 

 1933, 1935). 



