(S>35.30 °/oo) is centered between 800 m and 900 m depth and the 27.3 a^ and 

 27.5 a^ surfaces and is also characteristic of Red Sea Water. 



Sections 7 and 8, taken from 29 to 31 August 1979, were made to assess 

 the structure of the Socotra Eddy. The geostrophic currents (cm sec"l ) 

 calculated relative to 1500 dbar along these two sections are presented in 

 figure 44. Between stations 21 and 22 (11° 0.4'N, 55° 53.9'E) westerly- 

 setting currents down to about 1200 m are found with the strongest flow in the 

 upper 100 m exceeding 30 cm sec"K This is the westerly flow associated with 

 the southern edge of the Socotra Eddy. The strongest easterly-setting cur- 

 rents are found between stations 22 and 23 (13° 39.8'N, 56° 10.5' E) and in the 

 near-surface layers are in excess of 30 cm sec". This easterly flow is 

 associated with the northern half of the Socotra Eddy. Section 8, comprising 

 stations 23, 24 (11° 54.2'N, 57° 31.1'E), and 25 (9° 54.8'N, 59° 14.8'E), is 

 characterized by weak (<10 cm sec"^ ) easterly-setting surface and near-surface 

 currents. The dyanmic topography charts of the area (figures 32, 33, and 34) 

 indicate that section 8 parallels rather than crosses the northeastern edge of 

 the Socotra Eddy. 



The salinity analysis associated with section 7 and 8 is presented in 

 figure 45. Like the previous salinity cross-sections, sections 7 and 8 reveal 

 the complex and highly variable salinity structure of the upper and middle 

 depths of the northwestern Indian Ocean. The high surface salinities (S>35.7 

 °/oo) along these two sections identify this area as a source of high salinity 

 water. At stations 22 and 23 a salinity maximum (S>35.60 °/oo) is found at 

 about 300 m depth centered between the 26.4 a^ and 26.9 Of surfaces. This 

 water is characteristic of Persian Gulf Water. Between 700 m and 300 m a deep 

 salinity maximum (S>35.50 °/oo) is observed centered about the 27.3 o^ and 

 27.4 Of surfaces. The water associated with this salinity maximum is charac- 

 teristic of Red Sea Water. 



Figure 46 shows geostrophic currents (cm sec"^ ) along section 9 calculated 

 relative to 1500 dbar. This section was taken along the southern edge of the 

 Socotra Eddy and more nearly parallels than crosses the lines of constant 

 dynamic height. The weak northerly flow (<10 cm sec"') between stations 25 

 and 26 (9° 07.3' N, 57° 03.0' E) results from the trough in the dynamic topogra- 

 phy between the Socotra Eddy and Great Whirl (figure 32). Weak southerly flow 

 is found between stations 26 and 27 (7° 34.6'N, 55° 10.3'E) resulting from the 

 intermediate trough in the dynamic topography between the Socotra Eddy and 

 Great Whirl. This section was taken across an area of cyclonic shear between 

 these two eddies. 



The salinity cross-section associated with section 9 (figure 47) reveals 

 a general decrease of salinity with depth. The surface salinity maxima 

 (S>35.80 °/oo) at stations 25 and 26 is characteristic of Arabian Sea surface 

 water. At stations 25 and 26 salinity maxima (S>35.55 °/oo) is centered 

 between 200 m and 300 m depth and the 26.6 at and 26.7 ct+. surfaces. The depth 

 of occurrence and a^ values a,ssociated with these salinity maxima indicate 

 that this water has originated in the Persian Gulf. The weak salinity maximum 

 (S>35.45 o/oo) at station 26 is centered between 600 m and 700 m -"epth and the 

 27.2 Of and 27.3 a^ surfaces. This indicates that the water ha^ originated in 

 the Red Sea. 



17 



