An experimental study of relative contributions from surface and volume scattering mechanisms in saline ice

A randomly rough surface with Gaussian height distribution and a Gaussian correlation function was manufactured as a good conducting mold to generate a thin ice layer with the same surface geometry. This ice layer was superimposed on a thick smooth saline ice with known salinity property to form a saline ice medium with a known air-ice roughness characteristic. Multifrequency radar backscattering measurements were taken at C through X bands on the mold itself, and at X through Ku bands on the smooth saline ice medium before adding the rough ice boundary and after adding the rough ice boundary. Measurements of the mold were made to establish a reference for scattering. The objective of the ice measurements is to establish the contribution from surface roughness alone, from the smooth saline ice before and after adding roughness so that a clear understanding is achieved regarding the roles of surface and volume scattering and how these two mechanisms combine to total scattering from an inhomogeneous medium with irregular boundary. It is anticipated that because saline ice has a low albedo, the volume scattering contribution from it is not observable except at large angles of incidence. Results indicate that surface scattering dominates at small angles of incidence and its range of dominance decreases with an increase in frequency. This happens because the increase in volume scattering due to larger albedos exceeds the increase in surface scattering as frequency increases