SWELLS 



(LARGER 



WAVES) 



WIND 

 WAVES 



hS^.::*? 



MID WATER 

 SCATTERERS 



TIME (MIN) 



Surface roughness, with small wind waves superimposed on the swell, is recorded by a 

 bottom-mounted transducer. Most detail of the sea surface is obtained by this acoustic 

 method. 



•SWELL HEIGHT- 



-I 1 FT (- 



SUMMER SWELL 



Wave recorder has pressure and wave-period factors 

 incorporated in the electronics, so that wave heights 

 can be recorded directly on 0- to 5-, 0- to 10-, or 

 0- to 20-foot scales, at chart speeds of 12 or 60 

 inches per hour. 



WINTER SWELL 



There is a seasonal variation in swell height and 

 period. Such information on sea-surface roughness 

 is needed to interpret variations in acoustic 

 scattering from the upper boundary. 



45 



