DEPTH COMPENSATION 
To get the depth of the thermistor beads (in the next section 
it is shown how the depth of the isotherms is subsequently obtained) 
a pressure transducer is used. The zero adjust and the sensitivity 
are set in the laboratory and/or at dockside, so that the depth in- 
dicated by the pressure transducer system is the same as the keel 
depth as indicated by the master depth gauge (with the submarine at 
zero bubble). Underway, checks are made at various depths. 
Since the pressure transducer is quite linear, a linear interpola- 
tion between two check points that straddle the thermocline are 
used. Thus, the keel depth at zero bubble is given by 
A= Zip (6) 
where Z is the true keel depth, and z is that indicated by the pres- 
sure transducer. At the two check points 
Zi =a2, 4D, fad, 2 (7) 
al J 
and thus the constants qand } can be determined. Now qandb may 
drift slightly with time. If necessary, the values of aand b may be 
linearly interpolated between check points. 
Finally, the depth z,, of the Ath bead is given by 
i = + - 
ik az+(b D) (8) 
where 0 j, is the vertical distance of the thermistor to the keel. 
INTERPOLATION FOR DEPTH OF A GIVEN 
ISOTHERM 
The data obtained in the field for a given sequence of read- 
ings are the temperatures at several points on the strut and the 
strut depth. These data are not immediately useful. They can be 
used, however, to give isotherms along the track of the recording 
platform. 
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