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 associ ated with the boundary conditions along a sloping interface. Essential ly, the boundary condition for continuity of the normal displacement a long 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 deri vatives with respect to depth. The new sloping-boundary condition is t hen applied along an ''equivalent'' horizontal interface within each r ange-independent step of the PE. Numerical results obtained for standa rd test cases indicate that the sloping-boundary condition, incorporat ed into a one-way PE, maintains the efficiency yet improves the accura cy of forward predictions.