CALCULATIONS OF MIE BACK-SCATTERING FROM MELTING ICE SPHERES

Abstract

Calculations of the normalized back-scattering cross-section, σb, of ice spheres surrounded by shells of liquid water have been made from an extension of the Mie theory to a two-layer model. Curves of σb as a function of the thickness of the liquid-water shell are presented for various-sized spheres for 3.21, 4.67 and 10.0 cm radiation. It is shown that, depending upon the size of the sphere and the wavelength of the incident radiation, the back-scattering may either increase or decrease as the ice acquires a liquid-water shell. For certain-sized spheres, interference phenomena, which in some instances may lower the value of σb by several orders of magnitude, are in evidence during the course of melting.Comparisons are made between the theoretical results presented here and experimental measurements of σb for melting ice spheres performed by Atlas et al (1960).