An examination of the composite-roughness scattering model

Abstract

A perturbation technique is applied to derive a composite-roughness theory for acoustic scattering from the sea surface. The leading term in the expansion obtained is the well-known result obtainable using ad hoc arguments. Higher order terms are evaluated to assess their contribution to the high-frequency monostatic backscattering strength of the sea. It is concluded that the leading term in the perturbation expansion provides an excellent approximation.

High-order numerical solutions in frequency-independent computational times for scattering applications associated with surfaces with composite roughness

“…as in the (zeroth order) Kirchhoff approximation (KA) [5,6] (or its next order correction [7][8][9][10]) or the wellknown 'two-scale' method [6,[11][12][13][14][15] which has limited their applicability. This low-order nature of standard asymptotic approximations was largely due to the mathematical and implementational complications that arise in attempts at increasing their order.…”

Statistical characteristics of bistatic surface scatter and mean bistatic surface scattering strengths

“…Now define 0 2 as the lower bound on the region which is far from specular, which can be modeled using the Rayleigh-Rice approximation [12]. …”

Electromagnetic Scattering from Multiple Scale Geometries

“…(See e.g. [5] where the loss of accuracy of the two-scale model at low grazing angles is demonstrated. )…”

“…However, when a multitude of scales is present on the surface none of the techniques above is adequate, and attempts to combine them in a so-called twoscale approaches [2,4,5] have been given. The twoscale models imply a splitting of the surface into a large and small scale, see e.g.…”

“…The twoscale models imply a splitting of the surface into a large and small scale, see e.g. [5,6], where typically a first order approximation in wavelength (Kirchhoff approximation) is used to treat smooth components of a surface and a first order in surface height ) is used to deal with the rough components of the surface. The results provided by these methods are not always satisfactory -precisely as a result of the limitations imposed by the low orders of approximation used in both, the high-frequency approximation and the small perturbation methods.…”