

Temperature 

 Difference, °C 





Temperature 

 Difference, °C 



GULF OF ALASKA 



-0.17 



ORB-4 



0.02 



SUDS I 1972 





CAPER* 





LEE 



DE STEIGUER 



CAPE 



-0.05 

 0.23 

 0.05 



DE STEIGUER 

 MOAN A WAVE 

 FLIP 



0.03 

 0.12 



ORB-3 





RAPLOC/DEEPTOW 





System A 

 System B 



0.11 

 0.09 



System A 

 System B 

 System C 



-0.11 

 -0.16 

 -0.19 



*Not enough measurements to establish a final system error for FLIP. 

 Table 16. Final XBT system errors. 



from -0.1 9°C to 0.23°C. These errors are fixed and not random. The random errors are 

 the errors associated with repeated measurements made with the same system. To be 

 certain that the absolute value of the temperatures recorded by a given XBT system is 

 accurate, it appears necessary to determine the XBT system error. To do this, independent 

 and simultaneous temperature measurements are required. In the absence of these latter 

 measurements, the absolute value of the XBT recorded temperature is questionable if 

 accuracies in the average temperatures of better than about ±0.2°C are required. 



THERMISTOR CHAIN SYSTEM ERROR 



The thermistor chain is a towed device used for measuring temperatures from the 

 surface to a maximum depth of 242 m. It consists of 44 thermistors spaced 5.6 m apart, 

 plus associated shipboard equipment consisting of a winch and the necessary electronics for 

 recording the temperature as measured by the 44 thermistors. The instrument is designed to 

 measure a vertical temperature profile every 10 s with a resolution of ±0.03°C and an 

 estimated accuracy of about ±0.1 °C. 



During SUDS I, temperatures were measured simultaneously by the thermistor 

 chain hanging vertically in the water (zero tow speed) and the STD/SV system (reference 7). 

 STD/SV 3 was made to a depth of 312 m in 10 min, starting at 0415 LST on 12 February 

 1972. STD/SV 3 reached a depth of 242 m, the maximum depth of the thermistor chain 

 measurements, in 8 min at 0423 LST. During the period 0418-0422 LST, the chain made 

 27 scans of its sensors. Figure 9 summarizes the results of a comparison between these two 

 sets of measurements. The left-hand figure is a plot of STD/SV 3 at the thermistor chain 

 sensor depths.* The right-hand figure shows the differences between the average thermistor 

 chain measurements and the STD/SV 3 measurements at the same depths. Two features are 

 of interest. One is the relatively large differences from 96 to 124 m. These differences are 



"The STD/SV system measures temperature every 0.2 s and records the measurements on magnetic tape. 

 On the original tape the temperatures were missing at the depths where no temperatures are plotted in 

 figure 9 . 



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