NOTED 



Result 4 states "Comparison of XBT temperatures with average hydrocast and 

 STD/SV temperatures, quasisimultaneous STD/SV temperatures, and thermistor chain 

 temperatures taken under way at 3 knots shows that the 460-m XBT systems measure on 

 the average temperatures that are higher and vertical temperature gradients that are larger 

 than those measured by other systems." Note the use of the words larger and higher. The 

 mathematical convention that a positive number is larger than a negative number is used in 

 this paper. Thus a ±0.12°C/100-m gradient is larger than a -0.22°C/100-m gradient. If 

 the temperature differences are a positive increasing function of depth, the absolute value 

 of the gradient is reduced. However, if the above convention is used, the mathematical 

 value of the gradient becomes larger. Thus there is no contradiction. The author agrees 

 with the Sippican comment. It is a matter of definition of terms. 



NOTE E 



The simultaneous XBT measurements made on the ORB were by J. R. Lovett of 

 NOSC. The 1 830-m probes used were purchased from Sippican especially for this set of 

 measurements. No problems with wind, high seas, or salt buildup around the hps of the 

 launchers were encountered. However, according to J. R. Lovett, "The short deck cable 

 used with the 1 830-m probes constrained the location of the launcher to a position about 

 15 ft from an ORB cable. This adverse location probably accounted for most of the 

 catastrophic failures encountered with these deep probes." The relative location of the 

 launchers is noted in the section, Comparison of Simultaneous XBT Measurements. 



NOTEF 



Since each XBT probe has its individual rate-of-fall characteristic, this suggestion 

 can be used only where water depths are less than 460 m or 1 830 m, depending on the 

 type of probe used. Since many measurements are made in water depths greater than 

 these, the author feels that the incorporation of some simple sensor that would make one 

 depth measurement at some depth, such as 400 m, would greatly improve the vaUdity of 

 the assumption that depth can be determined from the fall time and, if there were a dis- 

 agreement between the two measurements, would provide a first-order depth correction. 



142 



