Modeling Land Surface Roughness Effect on Soil Microwave Emission in Community Surface Emissivity Model

Soil surface roughness is a crucial factor affecting the land surface microwave emissivity. Presented in this paper is a semiempirical model that analytically accounts for both roughness attenuation and cross-polarization-mixing effects in the frequency range of 1-100 GHz. The model is based on the finite linear superposition of hyperbolic tangent (tanh) functions over the normalized surface roughness and radiative parameter space, which proves to be very flexible and efficient in handling the distinct asymptotic features of roughness effects at the low-frequency end and high-frequency end and the nonlinear structure in between. The model performance was analyzed with the ground-based reflectivity measurements collected from different sources. In comparison with the existing semiempirical models in the literature, the new tanh-based roughness model demonstrated higher accuracy and consistent performance in the frequency range of 1.4-100 GHz and 0 degrees similar to 60 degrees incident angles.