WATER TEMPERATURES IN THE MARIANAS 

 TRENCH 



Above a deep trench, a unique characteristic of the 

 water column is the adiabatic increase of the temperature. 

 Wurst^® (192 9) has shown that a slight increase in temper- 

 ature can be anticipated below about 3000 fathoms. At this 

 depth a minimum temperature level occurs for water 

 masses of constant salinity. 



The temperature profile obtained during bathyscaph 

 Dive No. 70 (fig. 17) shows this minimum temperature 

 level followed by a gradual increase as the bathyscaph 

 descended. The recorded temperature values were acquired 

 using a resistance bridge. The accuracy of this bridge and 

 its calibrations were not adequate to permit the values to be 

 considered absolutely precise. 



The temperature at 3100 fathoms on Dive No. 76, as 

 determined by a reversing thermometer, was 2. 12 ± 0. 08° C. 

 A chart reading of 2. 3° C at the same depth in the same dive 

 was recorded. 



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