2. Applications 



In addition to the Intellectual satisfaction of completing the des- 

 cription of sea-floor depths, a stochastic model of high spatial fre- 

 quency submarine topography, or surface roughness, has many practical 

 scientific and engineering applications. Many of the most direct appli- 

 cations are In the field of underwater acoustics. Clay and Medwln 

 (1977) provide one of the best physical descriptions of the Interaction 

 of an acoustic signal with a rough surface. Matthews (1980) reviews the 

 Importance of relative scale In acoustic bottom Interaction. Briefly, 

 the relative spatial frequencies of the incident acoustic signal and the 

 bottom roughness determine whether the surface acts as a reflector or as 

 a scatterer of energy. This relationship Illustrates the necessity of 

 describing bottom roughness in terms of spatial frequency. 



The Importance of acoustics to marine geophysical surveying systems 

 cannot be overstated. Sea-floor bottom loss of sonar and seismic sys- 

 tems, ranging of side-scan sonars, and signal strength of outer beams on 

 multlbeam sounders all depend heavily on bottom roughness. In naviga- 

 tion applications, the roughness of the sea floor has an impact on the 

 backscattering of Doppler sonar, as well as determining the background 

 noise for navigation by bottom features. A major application for the 

 U.S. Navy of bottom roughness Information is as environmental input into 

 long-range acoustic propagation models, used in submarine and surface 

 ship tracking. For engineering applications, the a priori knowledge of 

 the spatial frequency composition of the bottom could be used in 



