Phase functions of large snow meltclusters calculated using the geometrical optics method

Abstract

Large snow meltclusters of 1 cm-order size are ubiquitously observed in summer snow cover on sea ice in the Southern Ocean. To study their effect on remotely sensed signals, we have to understand the absorption and single scattering properties of electromagnetic waves by these meltclusters. In this study, the meltclusters are characterized as spheres and scattering phase function and asymmetry factor are calculated on the basis of geometrical optics methods. The number of internal reflections and transmissions are truncated based on the ratio of incident irradiance at the n-th interface to the initial incident irradiance. The effect of finite size in absorption efficiency calculation using GOM method is corrected using Mie calculation. We use a combination of bracketing and a hybrid algorithm of bisection and Newton-Raphson methods to find the incident angles for a given scattering angle. The absorption efficiency, scattering efficiency, and phase function of a large single snow grain are calculated for the whole solar spectrum.