Generalized 3D Volume Scattering Modeling for Sea Ice Using SAR Polarimetry

In the model-based polarimetric decomposition for sea ice, the volume scattering of sea ice is usually modeled as the incoherent average of the scatterings of a large volume of oriented ellipsoid particles uniformly distributed in 3D space. This uniform spatial distribution is often approximated as a uniform orientation distribution (UOD), which is achieved by ensuring the Euler angles φ and τ of particles uniformly distributed in their respective ranges and introducing a factor cos τ in the ensemble average. However, this implementation of UOD is not always effective. By deriving the total solid angle of the ellipsoid particles and combining the differential relationship between solid angle and Euler angles, a complete expression of the joint PDF p(φ, τ) is realized in this paper, which can always ensure the uniform orientation of particles of sea ice. Then a generalized volume scattering model of 3D uniformly oriented particles is achieved by ensemble integrating the coherency matrix of a single (φ, τ)-oriented particle with p(φ, τ). The performance of model in the characterization of volume behaviors is investigated by simulation on a volume of oblate and prolate particles with three polarimetric descriptors.