AN EQUIVALENT FLUID APPROXIMATION FOR A LOW SHEAR SPEED OCEAN BOTTOM

The acoustic reflection coefficient for a homogeneous fluid over a homogeneous solid with a low shear speed is shown to be well approximated by replacing the solid with a fluid of different parameters. Explicit formulas for the density and attenuation coefficient of the equivalent fluid are given. Since the acoustic field in the upper fluid depends only on the reflection coefficient of the bottom, a uniform solid bottom with low shear speed can be approximated by assuming a fluid bottom with suitably chosen parameters. Shallow water examples are given.