Roger M. Oba
Naval Res. Lab., Stennis Space Center, MS 39529-5004
An inverse relation of bottom loss to frequency was successfully modeled by random fine-scale sediment layering [C. W. Holland and G. Muncill, J. Acoust. Soc. Am. 94, 1609--1620 (1993)]. A computational method for propagation of the Helmholtz equation in a water column with stochastic volume variation was developed to compute average complex pressure field and average square of the field numerically in a single pass. This model is revised for use in sediment with uncertain layering, assuming negligible shear interaction. A uniform upward refracting sediment has inclusions of fixed thickness, sound speed, and density, but of uncertain vertical spatial distribution. The vertical interlayer spacing is treated as a random variable with gamma distribution. This model also can be used to isolate phenomena associated with density variation versus sound speed variation. [Work supported by the Naval Research Laboratory and the Office of Naval Research.]