not very realistic. As on the previous two sections, the strongest north- 

 easterly-setting currents are found immediately adjacent to the coast where 

 cold, upwelled coastal water produces a pronounced trough in the dynamic 

 topography. The currents diminish in strength away from the Somali Coast. 

 However, records of ship set and drift along this section indicate that there 

 was a strong easterly component of the current at the surface that paralleled 

 rather than crossed the section. 



The salinity cross-section associated with section 4 (figure 41) is 

 highly complex and irregular. Relatively fresh (S<35.10 °/oo) water pre- 

 dominates in the upper 100 m at stations 17, 16, 15, and 14. This water is 

 advected eastward a considerable distance (about 250 nmi) off the Somali Coast 

 along the northern edge of the Great Whirl. Between 80 nmi and 100 nmi east 

 of station 14 a sharp surface salinity gradient is encountered which is also 

 evident in figure 19 as the boundary between relatively fresh (S<35.1 °/oo) 

 upwelled coastal water and relatively saline (S>35.6 °/oo) oceanic Arabian Sea 

 water. Below the subsurface layers three intermediate salinity maxima are 

 apparent, especially at station 14. The shallowest salinity maximum (S>35.40 

 °/oo) occurs between 300 m and 350 m depth at station 14 and is centered 

 between the 26.7 o^ and 26.8 a-j- surfaces. Although the salinity analysis 

 connects this salinity maximum with the highly saline (S>35.50 °/oo) surface 

 water east of station 14, the a-t values of 26.7 to 26.8 associated with it 

 suggest that the water may have originated in the Persian Gulf. Problems in 

 the analysis are posed by the long distance separating stations 13 and 14. 

 The next salinity maximum apparent at station 14 occurs between 500 m and 

 600 m depth and is centered about the 27.0 a^ surface which is intermediate 

 between Persian Gulf and Red Sea Waters. The deepest salinity maximum at 

 station 14 (S>35.40 °/oo) is centered near 900 m depth about the 27.4 at 

 surface and is characteristic of Red Sea Water. 



Figure 42 depicts the geostrophic currents (cm sec"^ ) relative to 1500 

 dbar along section 5 and 6 taken from 26 to 29 August 1979. The currents in 

 the near-surface layers are northeasterly-setting and quite weak (<20 cm sec"'), 

 The circulation in this area is chaotic and complex as indicated by the TIROS- 

 N Satellite infrared image for 27 August 1979 (figure 3), and it is highly 

 likely that the wide spacing of STD stations has aliased out important small 

 scale features of the thermohaline structure in the area. Moreover, section 5 

 parallels rather than crosses the lines of constant dynamic height anomalies. 



Figure 43 reveals the irregular salinity structure associated with 

 sections 5 and 6 in the upper and middle depths. Again, several intermediate 

 salinity maxima are apparent. A near-surface salinity maximum at station 18 

 (9° 42.4' N, 52° 03.4' E) is centered at about 70 m depth and the 25.9 at 

 surface. This salinity maximum breaks the surface along section 6 thus indi- 

 cating that the formation area of this water lies in the high evaporation area 

 of the Arabian Sea. The next salinity maximum (S>35.30 °/oo) is found at 

 stations 18 and 19 (11° 14.8'N, 52° 31.7'E) between 200 m and 300 m depth. 

 Being centered between the 26.5 at and 26.9 at surfaces this water exhibits 

 characteristics of Persian Gulf Water. Station 21 (9° 21.0'N, 54° 33.0'E) is 

 characterized by a strong (S>35.50 °/oo), deep (400 m to 600 m) salinity 

 maximum. This water, owing to the depth and strength of the salinity maxi- 

 mum, most likely originates in the Red Sea. The deepest salinity maximun) 



16 



