PROCESSING PROCEDURES 



Figure 10. — Graph for determining thermometric depth 

 anomaUes from corrected thermometer readings, 

 7"u~ Tai and thermometer constant, Q. 



slightly with depth at a rate comparable to the 

 rate of increase with depth of p„. Thus p^Q 

 would be nearly constant, and depth would be 

 almost directly proportional to the difference in 

 corrected thermometer readings. If this is true 

 the curves of figure 10 will be nearly straight 

 lines. 



When depth of reversal has been determined 

 for each water bottle to which an unprotected 

 thermometer was attached, depths of reversal 

 of the intervening water bottles in the series are 

 found. One method is to calculate the ratio 

 of depth to wire length for each water bottle of 

 known depth, the meter wheel readings of wire 

 length having first been corrected for cali- 

 bration. Next the ratio is plotted against wire 

 length as shown in figure 1 1 , and a smooth 

 curve drawn through the points. Values of the 

 ratio are read from the curve for the wire length 

 to each bottle and multiplied by the wire length 

 to obtain the depth of reversal of each bottle. 

 This depth is frequently called the accepted 

 depth. An example of the calculation is shown 

 below in figure 12. The data used for illustra- 

 tion are from the sample station to be discussed 

 in detail later in section D.4, page 19. The 

 figure entered in the ratio column at zero wire 

 length and plotted at the top of the graph is 

 the cosine of the wire angle at the surface, and 

 thus represents the ratio of depth to wire length 

 at the surface. If the wire angle is small the 

 ratio is nearly constant and approaches unity. 

 However, if the angle is large the ratio usually 



Figure 11. — Graphs for determining depths of observations 

 between calculated thermometric depths by the ratio 

 method (thermometric depth divided by wire length). 



*Cosine of wire angle 35°. 



Figure 12. — Example of calculating depths of observations 

 by ratio method. 



