SUMMARY 



During six acoustic experiments conducted between 1971 and 1975, a total of 1978 

 XBT temperature profiles were acquired - 26 by means of 1830-m XBT systems and 1961 

 by means of 460-m systems. Included were special sets of measurements that provided data 

 bases for absolute and relative accuracy studies. The measurements were made on eleven 

 460-m and two 1830-m systems from four ships and two research platforms. In addition, 

 independent temperatures were measured by using hydrocasts, STD/SV, thermistor chain, 

 surface towed thermistors, and bucket thermometers. 



It is common practice to read XBT analog records visually with a temperature 

 accuracy of ±0.2°C and a depth accuracy of ±2 m. In this study, all XBT records were read 

 with a Hewlett-Packard 9864A Digitizer that has a temperature resolution of ±0.05°C and a 

 depth resolution of ±0.94 m. 



XBT PERFORMANCE 



The following is a summary of the performance of the XBT systems used to provide 

 the data for this study. 



460 m 1830 m 



Profiles attempted 

 Catastrophic failures 

 Miscellaneous failures 

 Partial successes 

 Successes 

 Visually acceptable 



where the above categories are defined as follows: 



Catastrophic failure — No usable measurements for depths greater than 50 m. 



Miscellaneous failure — Failed because of operator error, wire blowing 

 against ship, etc. 



Partial success - Visually acceptable to a depth greater than 50 m but less 

 than the maximum depth. 



Success — Visually acceptable to maximum depth. 



Visually acceptable - The sum of the successes and partial successes. No 

 basis for rejecting as incorrect based on a visual inspection of the analog 

 record. 



SYSTEM MEASUREMENT ERRORS 



STD/SV, CTD/SV, SVTP, XBT, thermistor chain, towed thermistor, and bucket 

 thermometer temperatures were compared with hydrocast measurements to determine the 

 corrections required to bring these measurements into agreement with the hydrocast 

 measurements. These corrections are referred to as the system errors. 



126 



1961 



100.0% 



26 



100.0% 



126 



6.4% 



8 



30.8% 



52 



2.7% 







0.0% 



212 



10.8% 



8 



30.8% 



1571 



80.1% 



10 



38.4% 



1783 



90.9% 



18 



69.2% 



