5aUW10. Modeling shallow-water propagation with an appropriate sea-surface roughness spectrum.

Session: Friday Morning, December 6

Time: 9:52

Author: Guy V. Norton
Location: Naval Res. Lab., Stennis Space Center, MS 39529-5004
Author: Jorge C. Novarini
Location: Planning Systems, Inc., Long Beach, MS 39560-9702


Predictions for shallow-water acoustic propagation are usually accomplished assuming a deep-water spectrum for the sea surface roughness. In addition, the effect of surface roughness is normally included through a loss mechanism. However, for waveguide propagation, the surface roughness mainly causes a redistribution of energy and therefore, the use of an accurate model to handle roughness is essential to obtaining accurate results. In order to properly model shallow-water surface roughness, the parametric spectrum GONO [Sanders and Bruinsma, Wave Dynamics and Radio Probing of the Ocean Surface, edited by O. M. Phillips and K. Hassemann (Plenum, New York 1986), pp. 615--637] has been implemented. This spectrum is appropriate for wind-driven surfaces in waters ranging in depth from 15 to 100 m. To investigate the impact that different spectra has on the propagating field, predictions using GONO and Pierson--Moskowitz spectra are compared for different environments and at frequencies typical of active and passive sonars. An acoustic propagation model, which includes a conformal mapping algorithm to properly handle sea surface roughness [Norton et al., J. Acoust. Soc. Am. 97, 2173--2180 (1995)] is used to generate the numerical results. [Work supported by ONR.]

ASA 132nd meeting - Hawaii, December 1996