TRANSDUCER HORIZONTAL 



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100 



200 300 500 700 1000 2000 5000 10,000 



3000 7000 



RANGE IN YARDS 



Figure 23. Dependence of standard reverberation level on range and wind speed. 



100 200 300 500 700 1000 



RANGE IN YARDS 



2000 3000 



Figure 24. Sample plot of standard reverberation 

 level at high wind speed. 



groups, two pairs of which were taken in the same 

 area at different seasons. The data grouped in this 

 way are summarized in Table 1. On the whole, Table 

 1 shows that the mean reverberation levels at 1,500 

 yd are independent of season and area, although the 

 Cedros II and Point Conception data may indicate 

 some systematic variation. 



Figure 26 is an analysis of the dependence of the 

 observed reverberation levels on a parameter which 

 has been found to correlate significantly with trans- 

 mission studies at 24 kc. This parameter is the depth 

 -D2 in the ocean at which the temperature is 0.3 F less 

 than at the surface.'' The levels in Figure 26 are re- 

 ferred, for convenience, to an arbitrary zero level 

 which was, however, the same for all curves. Only 

 data obtained after March 22, 1944 were used for 

 this comparison since most of the earlier runs ended 

 at about 2,000 yd. The median curves are seen to be 

 practically the same for Dj between 5 and 40 ft, 

 but fall off less rapidly for D^ between 40 and 160 ft. 

 Since, according to reference 7, increasing D2 means 

 a decreasing transmission anomaly A in equation 



