SUPERSONIC TRANSMISSION 



153 



RAY DIAGRAM AND BOTTOM PROFILE 



BT INFORMATION 



50 60 70 



TEMPERATURE F 



2000 4000 6000 



RANGE IN YARDS 



Figure 11. Transmission run over MUD with NAN pattern. 



HaTf 6-1-1944 

 TIME 1415 



BT CLASS NAN 



WATER nrCTu 47 FM 



I 



SWELL. 

 WIND 



Forty-six runs were made in water of 6 fathoms or 

 less and over SAND bottoms. These runs were 

 analyzed as a separate group. Table 5 summarizes 

 the results. Figure 13 shows the complete distribu- 

 tion of SAND runs. 



The majority of the runs used in this analysis were 

 carried out in the presence of downward refraction, 

 but no attempt was made to separate the runs with 

 downward refraction from those with the projector 

 located in a mixed laj'^er. This method of analysis may 

 account for the wide quartile spread and more par- 

 ticularly for the great upper quartile spread for wind 

 force 4. The reduction of Rao between wind force or 1 

 and 3 amounts to an increase in the slope of the trans- 

 mission anomaly curve of roughly 1 db per kyd. 



6.2.3 Summary 



Transmission experiments at 24 kc indicate that 

 the sea bottoms can be roughly divided into well- 

 reflecting bottoms comprising ROCK, CORAL, 

 STONY, SAND, and CLAY bottoms, and poorly 

 reflecting bottoms, mostly MUD and some of the 

 SAND-AND-MUD. Most of the SAND-AND- 

 MUD bottoms are intermediate between well and 



Table 4. Rw versus wind force over SAND in water 

 depth greater than 6 fathoms. 



poorly reflecting bottoms. Present evidence indicates 

 that in shallow water at least 10 fathoms deep and in 

 the presence of downward refraction, transmission 

 anomalies over SAND and STONY bottoms increase 

 with the range by 5 + 2 db per kyd, and over 

 ROCK bottoms by 6 + 2 db per kyd. The trans- 

 mission is not significantly affected by hydrophone 



