Accession Number : AD0614196

Title :   ANALYSIS OF SPREADING LOSS FOR REFRACTED/ REFLECTED RAYS IN CONSTANT-VELOCITY-GRADIENT MEDIA,

Corporate Author : MIAMI UNIV FLA MARINE LAB

Personal Author(s) : Jacobson,M. J.

Report Date : 11 JUN 1964

Pagination or Media Count : 8

Abstract : The analytical properties of existing spreading-loss formulas are not well-known in the case where a ray experiences multiple boundary reflections. This paper investigates spreading loss in detail for refracted/ bottom-reflected rays when the velocity gradient is a negative constant and the bottom is horizontal. Expressions for the spreading loss are derived, special cases are examined, and upper bounds are obtained. It is shown that there are some points on every ray at which the spreading loss is less than inverse-square loss and some points on some rays at which the loss exceeds inverse-square loss. The loss behavior is examined as a ray path is traversed, and is found to be markedly dependent upon initial ray inclination, the ray lobe being considered, and velocity structure. The problem of multiple arrivals at a fixed receiver is also studied. Relationships are given between the number of arrivals and their intensity, travel time, initial inclination, and number of reflections. Two examples are presented. The results in this paper apply not only to refracted/ bottom-reflected transmissions, but also to surfacechannel and deep-sound-channel transmissions. (Author)

Descriptors :   (*SOUND TRANSMISSION, UNDERWATER), (*ACOUSTICS, UNDERWATER), ATTENUATION, REFRACTION, REFLECTION, UNDERWATER SOUND, MATHEMATICAL ANALYSIS

Distribution Statement : APPROVED FOR PUBLIC RELEASE