Radar scattering by boulders studied using geometric optics

We simulate radar scattering from meter-scale boulders of ice and rock using an algorithm of geometric optics. The scattering particles are Gaussian-random-sphere particles with different levels of irregularity. We study the effect of particle size, geometry, and material on the radar albedo and circular polarization ratio at microwaves concentrating on the S-band wavelength of 12.6cm. We show that increased absorption causes the radar albedos in both polarization states to attenuate exponentially when the contribution of the internally scattered waves decreases. Consequently, also the polarization ratio decreases. Semi-empirical models for the radar albedos are derived. •Computations for electromagnetic scattering by Gaussian-random-sphere particles in the geometricoptics regime are presented.•Semi-empirical equations for the radar albedos are derived.•Applications to radar scattering by boulders of rock and ice are discussed.