A SLOPING BOUNDARY CONDITION FOR EFFICIENT PE CALCULATIONS IN RANGE–DEPENDENT ACOUSTIC MEDIA

The traditional one-way parabolic equation (PE) formulation for range-dependent layered acoustic media is modified to include effects associated with the boundary conditions along a sloping interface. Essentially, the boundary condition for continuity of the normal displacement along a sloping interface is cast in an approximate form which does not depend on range but does contain terms up to second order in the derivatives with respect to depth. The new sloping-boundary condition is then applied along an "equivalent" horizontal interface within each range-independent step of the PE. Numerical results obtained for standard test cases indicate that the sloping-boundary condition, incorporated into a one-way PE, maintains the efficiency yet improves the accuracy of forward predictions.