Accession Number:

AD0466138

Title:

A DETAILED STUDY OF SOUND REFLECTIONS FROM A LAYERED OCEAN BOTTOM.

Descriptive Note:

Technical rept.,

Corporate Author:

SACLANT ASW RESEARCH CENTRE LA SPEZIA (ITALY)

Personal Author(s):

Report Date:

1965-05-15

Pagination or Media Count:

44.0

Abstract:

The effect of layered sediments on sound reflection from the ocean bottom has been investigated theoretically and experimentally. Very detailed, systematic and computer-aided calculations of the reflection coefficient of a twolayer bottom are made, using well-known theory and varying the following parameters 1 velocity and density contrasts 2 layer thickness normalized with respect to wavelength 3 absorption in the sediments in dbwavelength 4 shear wave velocity in the lower layer. Calculations are made both for a harmonic source and for a broadband source analysed within certain bands around the harmonic source frequency. A series of curves is obtained representing the two-layer effect for a range of parameters that encompasses typical ocean bottom values. It is shown that absorption in the upper layer is of great importance in sound reflection, especially beyond a critical angle, but that moderate shear wave velocities have little effect. An octave band analysis of experimental data -- using a broadband source -- tends to support this theoretical two-layer model. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE