Temperature : South-west Monscxdn 



At the Surface (Chart 13). — The surface temperatures during the 

 second survey were not greatly different from those during the first survey. 

 The values were mostly within one-half degree of 29 • 5° c. throughout. 

 Temperatures were over 30-0° c. south of Negros and at two stations 

 in the north. It is interesting to note that, although the north-eastern 

 half of the area was surveyed in the middle of June and the south- 

 western half during the middle of July, somewhat higher temperatures 

 were found in the north-eastern portion as was the case during the north- 

 east monsoon when the area was surveyed in October and December. 



At 50 Metres (Chart 14). — -The temperatures at the 50-metre level at 

 this season showed a much more complex condition than at this level 

 during the north-east monsoon, indicating that the depth of the wind 

 layer was less than during the north-east monsoon. A centre of high 

 temperatures in the north corresponding to the North Central Eddy 

 had values above 29-0° c. Another such centre occurred to the south 

 and corresponds to the anticyclonic eddy to the south of the South 

 Central Eddy. Between these two centres there is a small centre of low 

 temperature with values around 27-0° c. To the west is a centre with low 

 values, less than 25-5° c. Comparatively low temperatures were found 

 east of Palawan. 



At 75 Metres (Chart 15). — The pattern of horizontal temperature 

 distribution at the 75-metre level is similar to that at 50 metres, except 

 that the centres of low and high temperature are not so pronounced. 

 The highest value was 27-68° c. in the North Central Eddy ; the lowest 

 value was 23-63° c. in the South Central Eddy. Lower temperatures 

 were found at 75 metres west of Balabac Strait in the China Sea, but this 

 cold water apparently did not enter the Sulu Sea. As at the 50-metre 

 level, the water east of Palawan was colder than that farther east in the 

 Sulu Sea. 



An outstanding feature of the temperature distribution at 75 metres 

 during the south-west monsoon is the lower values observed. Throughout 

 most of the year the temperatures are from 0-5° to 1-0° lower than during 

 the north-east monsoon. Along Palawan the difference is about 2-0° 

 with temperatures near 25° c. during the south-west monsoon. : 



At 100 M\etres (Chart 16). — The distribution of temperature at 100' 

 metres during the south-west monsoon is dominated b};^ a centre of low 

 temperatures corresponding to the South Central Eddy. Values here are 

 less than 21° c. At the 100-metre level, as at the 75-metre level, the 

 temperatures during the south-west monsoon were lower than during the 

 north-east monsoon. 



At 200 Metres (Chart 17).— The temperatures at the 200-metre 

 level are remarkably similar to those for this depth observed during the 

 north-east monsoon. Apparently seasonal changes in the temperature 

 of the Sulu Sea do not extend to the 200-metre level. 



At the 400-metre level and the 800-metre level the horizontal dis- 

 tribution of temperature is just as uniform as at these levels during the 

 north-east monsoon. 



Salinity : North-east Monsoon 



At the Surface (Chart 18). — The salinity in the eastern third of the 

 Sulu Sea during the first survey was about 33-8 "/oo. To the north-west 

 and in the southern portion the values were near 33-2°/oo- A centre 



244 



