Scattering and emission models for microwave remote sensing of snow using numerical solutions of maxwell equations

Snowpack consists of ice grains that are densely packed in the wavelength scale at microwave frequencies so that the coherent microwave interactions among the ice grains are important in microwave signatures. We have used Numerical Maxwell Model of 3D simulations (NMM3D) of random media / discrete scatterer to study such interactions. In the partial coherent model of Dense Media Radiative Transfer (DMRT), we use NMM3D to calculate the effective propagation constants, the extinction coefficients and the phase matrices. These are then used in radiative transfer equations to calculate the emission and backscattering signatures. In the fully coherent model, we use NMM3D to calculate the bistatic scattering and emissivity for a layer of snow pack over the ground. Using the fully coherent approach, we calculate the complex scattering amplitudes from the snowpack, including both magnitude and phase. In microstructure characterization of snow, we have used 2 models a) densely packed scatters of sticky particles or multiple sizes, and b) computer generated bicontinuous media. Both models can be characterized by correlation functions. In this paper, we also describe the recent simulated results for tomography and co-polarization phase differences of anisotropic dense media.