A numerical study of thermal emission from random dielectric rough surfaces with the SMCG/PBTG method

The 3-dimensional simulations of emissivities from a two-dimensional wet soil with random rough surfaces are studied with numerical solutions of Maxwell equations. The wet soils have large permittivity. Thus a dense discretization of the surface is required to implement the method of moment (MoM) for the surface integral equations. Such a dense discretization is also required to ensure that the emissivity can be calculated to the required accuracy of 0.01 for passive remote sensing applications. It has been shown that the physics-based two-grid method (PBTG) can efficiently compute the accurate surface fields on the dense grid. In this paper, the numerical results are calculated by using the PBTG in conjunction with the sparse-matrix canonical grid method (SMCG). The emissivities are illustrated for random rough surfaces and physical parameters of roughness for different soil moisture conditions. The results are calculated for L and C bands using the same physical roughness parameters. The numerical solutions of Maxwell´s equations are also compared with the popular H and Q empirical model showing that H and Q are dependent on soil moisture, vary angle and frequency