Accession Number:

AD0730393

Title:

Intensity-Range Relations in Oceanographic Acoustics,

Descriptive Note:

Corporate Author:

ADMIRALTY RESEARCH LAB TEDDINGTON (ENGLAND)

Personal Author(s):

Report Date:

1971-03-01

Pagination or Media Count:

30.0

Abstract:

A universal graph is presented for constant-depth isovelocity water, with range and frequency both scaled according to the water depth. Five acoustic propagation regions are delineated spherical spreading, cylindrical spreading, three-halves spreading due to mode stripping, single mode, and bottom path. Very simple derivations of the transmission-loss formulae are given, using an energy-flux approach which allows for the various boundary losses. Comparison is made with experimental intensity-range curves, and also with independent measures of the ray angles or modes effective in carrying the energy. It appears that the simple formulae are meaningful, and useful especially as a guide to understanding. But there are many important extra effects, such as the attenuation due to fish for which check lists are provided. These extras are different for shallow compared to deep water. A special treatment is included for mode stripping over a sloping bottom, including the case of an arbitrary depth profile. Author

Subject Categories:

  • Acoustics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE