EFFECT OF AIR BUBBLES ON RADAR BACKSCATTERING BY HAILSTONES

Computational results have been obtained for radar backscattering cros s sections of spherical model hailstones containing air bubbles inside the surface water or spongy ice layer. The effective refractive indic es of water-air or water-ice-air mixtures have been obtained using the Maxwell-Garnett and Bruggeman effective medium approximations. The ra dar backscattering cross sections have been calculated for a layered s phere composed of an ice core and water-air or ice-water-air outside l ayer. The amount of air in a surface layer was varied between 0% and 2 0% by volume. The presence of air bubbles in the surface layer shifts positions of the backscattering peaks and modifies the backscattered i ntensities at peak values. The dependence of the backscattering cross section on the air bubbles volume fraction is stronger at shorter wave lengths.