IV. DISCUSSION OF RESULTS 



The area of turbulence In the Indian Ocean, in the areas examined by 

 EASTWIND, extended from the surface to a depth of about 50 meters, and in 

 places somewhat deeper. As in other oceans, conditions in this region were 

 fairly stable and uniform, but below this depth sudden and pronounced changes 

 were encountered as the thermocline was reached. Below the thermocline at 

 depths of from 200 to 600 meters, depending upon the geographic location, 

 conditions tapered off slowly to the deepest observations. Despite the rough 

 and variable bottom contour along the 32° S. parallel (Figs. 2 through 7), 

 conditions did not show any striking trends. On the south-north profiles along 

 the 78° E. meridian (Figs. 8 through 13), salinities and dissolved oxygen pre- 

 sented a complex pattern that indicated a divergence or upwelling between 

 stations 11 and 16, at about 10° and 18° south latitude. The profiles constructed 

 between stations 27 and 30 (Figs. 14 through 19), are somewhat artificial be- 

 cause of the wide spaces between stations and because of the existence of the 

 Maldlve Islands between stations 27 and 28. For this reason, these two stations 

 were connected by broken line isopleths. Also, station 30, off Socotra Island, 

 was taken at a considerably shallower depth than most of the other stations; and, 

 as a consequence, without Intervening data, isopleths at the lower depths were 

 shown as terminating at an indefinite point. 



A . Temperature 



As depicted in Figures 2 and 20, temperatures along the 32° S. parallel 

 from 1 10° to 78° E. in the zone of turbulence showed only a slight Increase 

 toward the west. The comparatively shallower water between 96° and 102° E. 

 was reflected slightly in the curves of the isotherms at depth; all isotherms below 

 the turbulence zone remained roughly parallel to the surface. The thermocline 

 (and here the word is used in Its strictest sense, namely a sustained drop of at 

 least 1°C. per 30 meters change In depth) was located between 30 and 50 meters 

 down to a depth of only 100 meters as far as station 5. The 2° Isotherm was 

 found throughout this section at depths between 2200 and 2500 meters. Substan- 

 tially the same temperatures at depth were observed by DIAMANTINA in 1959 

 (C.S.I.R.O., 1962) although her temperatures were somewhat lower (17° to 

 19°) In the zone of turbulence because of the time of year (November) at which 

 the temperatures were taken . 



The most Interesting profile Is the one starting at 32° S . latitude and 

 running north along the 78° E. meridian to 4° N. latitude. This profile com- 

 prised 23 stations. (Fig. 8, 20, 21, and 22). Stations were occupied at 2° 

 Intervals as far north at 4° S . latitude and at 1° intervals from there to 4° N. 

 latitude. In the zone of turbulence, which showed a slight Increase in depth 

 (from 30 to 75 meters) until 13° S . was reached, temperatures Increased from 



31 



