Polarimetric scattering coefficients of half-space heterogeneous medium

摘要

Almost all natural media such as a rain, ice, fog, snow, clouds, leaves, forests, surface soil layer, agricultural plants, etc. can be considered as some kind of heterogeneous random medium embedded with nonspherical discrete particles. In this paper the polarimetric backscattering coefficients of half-space random medium are calculated for the purposes of the environmental remote sensing using polarimetric radars. The stochastic model of the half-space heterogeneous medium consists of a random current propagating in a hypothetical isotropic medium. The parameters of the model used in this paper are derived by the aid of strong permittivity fluctuation theory under a bilocal as well low-frequency approximations. The symmetry of scattering matrix F was proven in backscattering direction of measurement of scattered electromagnetic field in the atmosphere. It was shown that the polarimetric covariance matrix C consists of two polarimetric covariance matrices of unperturbed and random parts of scattered electromagnetic field. It was as well shown that in backscattering direction the scattering coefficients /spl sigma//sub hv/, /spl sigma//sub hhhv/, /spl sigma//sub hvvv/ are different from zero in general. The expressions of polarimetric backscattering scattering coefficients given in this paper are valid for arbitrary joint probability density function P(/spl theta/,/spl phi/) of scatterers spatial orientation. The obtained results can be used for the purposes of polarimetric remote sensing of heterogeneous natural media embedded with discrete scatterers having non spherical geometry.