A SEA FLOOR MICROROUGHNESS SCALE AND 

 WORLDWIDE ZONES OF ISOROUGHNESS 



Microrelief Numerical Ratings 



Individual descriptions of sea floor microrelief, and 

 predictions of its environmental distribution, have little 

 practical value unless the results can be expressed quanti- 

 tatively. In a numerical form, however, roughness of the 

 sea floor can be correlated with other factors influencing 

 the transmission of underwater sound, such as sediment 

 properties, sound velocity, temperature, salinity, and 

 larger topographic features. 



An arbitrary scale of sea floor roughness has been 

 developed from the measurements and photo-interpretations 

 of table 1, and is presented here as table 3. In addition to 

 numerical ratings, table 3 includes an explanation or defini- 

 tion of the meaning of each rating. 



This numerical scale of sea floor microroughness 

 is a beginning attempt, with a minimum of data, to provide 

 a means of predicting microrelief for acoustic purposes. 

 It is hoped that roughness ratings for all sea floor areas 

 can eventually be obtained for use in both military and 

 commercial applications. The success of this endeavor 

 will depend on the accumulation of more and better data, 

 and particularly on accurate ship positioning, camera 

 control, and depth measurement. 



A summary of microrelief characteristics follows 

 which, it is hoped, will make the ratings more useful. 



TABLE 3. NUMERICAL SCALE OF SEA FLOOR MICROROUGHNESS AND DESCRIPTIVE NOTES 





Numerical Rating 

 of the Relief 



Canyon — inner 



5 



Bank 



4 



Irregular topography 



4 



Smal 1 local ridge 



4,3 



Island slope 



4,2 



Local ridge 



3,4 



53 



