Scattering and Emission in Snow Based on QCA/DMRT and Numerical Maxwell Model of 3Dimentional Simulations (NMM3D)

An important application of dense medium is in microwave remote sensing of snow because the ice grains in snow are densely packed together. Classical radiative transfer theory assumes that the particles scatter independently. There are four major physical features in the results of classical theory, when applied to snow grains at microwave frequency from 5 GHz to 37 GHz. (1) For particle sizes small compared with wavelength, scattering is proportional to frequency of the 4th power. (2) Scattering is proportional to concentration. (3) Using classical Mie theory or Rayleigh theory, the phase matrix is close to that of the Rayleigh phase matrix so that the mean cosine of scattering is equal to or approximately equal to zero (4) The Mie phase matrix or the Rayleigh phase matrix has zero cross polarization in the plane of incidence. In dense media, the classical approach of independent scattering is not valid. We have used analytical QCA/DMRT model and numerical solutions of Maxwell equations in 3D simulations (NMM3D). In this paper, we compare the results of extinction and phase matrix among classical, QCA/DMRT and NMM3D using the same physical parameters of particle sizes, permittivity and fractional volumes. We discuss the differences and similarities of the four physical features of the results