EVALUATION OF THE SPARTON TIGHT-TOLERANCE AXBT

Forty-six near-simultaneous pairs of conductivity-temperature-depth (C TD) and Sparton ''tight tolerance'' air expendable bathythermograph (A XBT) temperature profiles were obtained in summer 1991 from a location in the Sargasso Sea. The data were analyzed to assess the temperature and depth accuracies of the Sparton AXBTs. The tight-tolerance criter ion was not achieved using the manufacturer's equations but may have b een achieved using customized equations computed from the CTD data. Th e temperature data from the customized equations had a one standard de viation error of 0.13-degrees-C. A customized elapsed fall time-to-dep th conversion equation was found to be z = 1.620t - 2.2384 X 10(-4)t2 + 1.291 x 10(-7)t3, with z the depth in meters and t the elapsed fall time after probe release in seconds. The standard deviation of the dep th error was about 5 m; a rule of thumb for estimating maximum bounds on the depth error below 100 m could be expressed as +/-2% of depth or +/-10 m, whichever is greater. This equation gave greater depth accur acy than either the manufacturer's supplied equation or the navy stand ard equation.