Surface water, and from 250 to about 600 meters Is Indian Central water. The 

 Antarctic Intermediate water had become mixed with other water and salinity 

 had increased; however, there are some indications of this water on the T-S 

 curve and also on Figure 9 below 600 meters. 



By the time station 17 was reached, the last traces of Antarctic Intermediate 

 Water had been left behind (Fig. 24C). The upper 50 meters contains low salinity 

 water from the Malay Archipelago. Subtropical Surface water extends from 50 

 to 100 meters, and below this is the Indian Central water mass. Station 20 

 (Fig. 24D), shows a T-S curve similar to that at station 17. At station 23 on 

 Figure 25A, there is an isothermal mixed surface layer. Below that, from 20 to 

 75 meters is Malay Archipelago water, and below that to about 500 meters 

 Indian Central water. 



Station 27, shown on Figure 25B, was taken on 15 April, with the season 

 progressing toward maximum air temperatures in May. The top, almost isothermal, 

 mixed, surface layer shows this. Below this/to 250 meters, is the thermocline cir- 

 culation. Indian Central water is found below 250 meters. Station 28 (Fig. 25C), 

 occupied on 22 April shows further evidence of approaching high air tempertures 

 in the top 50 meters. From 50 meters to 200 meters the Indian Equatorial water 

 mass is present. From 200 meters down to about 1000 meters the effect of Red 

 Sea water is evident, with the cooler, less saline water below this level . At 

 station 30/influence of Red Sea water is pronounced in the top 150 meters. Below 

 150 meters the water mass is Indian Equatorial water. 



A series of 22 surface salinity samples taken from the southern entrance to 

 the Red Sea at 12° 27' N., 44° 09" E. to the extreme end at 28° 45' N., 

 32° 57' E. (Table I), showed a steady and at most times regular salinity increase. 

 Salinity (36.27%0) at the first sample location was almost exactly that found at 

 survey station 30. This was apparently normal surface salinity for the greater 

 part of the Gulf of Aden because of the broadening out of the water area after it 

 passes the strait of Bab el Mendab . Half way up the Red Sea proper, salinity had 

 reached 39.00%o, and 40.00%nwas attained before entering the narrow portion 

 near the northern end. The highest salinity observed was at the most northern 

 collection point . It was 41 .57%;,. 



36 



