Radar scattering by volcanic debris flow surface analogues

Measured roughness spectra from 10-year-old primary volcanic debris flows at Mount St. Helens conform to a power-law spectral model. It is difficult to rigorously test rough surface scattering models using in situ measurements of radar backscatter because natural targets are often inhomogeneous or non-stationary, because volume scattering may he significant, and because characterisation of natural rough surfaces is difficult and time-consuming. The authors have manufactured debris flow surface analogues by milling rough surfaces with specified power-law roughness spectra on homogeneous slabs of polyethylene. Measured radar backscatter from these surface analogues provides test data for scattering studies. The surface analogues serve as test surfaces which are homogeneous, well characterized, and free of volume scattering effects