Measured surface spectrum dependence of backscattering from rough surface

The wavelength dependence of backscatter from a smoothly undulating randomly rough surface was measured over a broad continuous range of wavelengths using acoustic waves in water. The experiment resulted in discovering a transition region in which the wavelength dependence changed abruptly from
\lambda^{0}
to
\lambda^{+3}
, apparently due to change in the surface height spectrum. The wavelength dependence corresponded to the measured surface height spectrum through the transition region in the manner predicted by the composite surface model formulated by Wright and others. A similar spectrum-dependent effect has been found in broad-spectrum electromagnetic measurements of natural surfaces.