A Backscatter Model for a Randomly Perturbed Periodic Surface

A backscatter model for a randomly perturbed periodic surface has been developed to explain backscatter measurements from a bare soil surface with row structure. It is assumed that the rowdirection effect can be included by integrating the scattering coefficient σˢˢ (θ') due to the random roughness component over the underlying periodic component of the soil surface. It is found that the rowdirection effect is strongly dependent upon the rate-of-change of σˢˢ (θ') with the local angle θ' and that for sinusoidal surfaces, the maximum difference between looking parallel and perpendicular to the row direction occurs around an incidence angle whose tangent is usually smaller than the slope of the periodic surface at the inflection point.