Effect of soil roughness on microwave emission: comparison between experimental data and models

The influence of surface roughness on microwave emission from soil has been analyzed using experimental data at L X and Ka bands and theoretical models with appropriate approximations for each frequency range. Soil emissivity has been predicted from reflectivity by using the Kirchhoff approach (geometrical optics) at the higher frequencies and the small perturbation method at L band. The emissivity of smooth soil has been computed considering the soil as a homogenous medium at uniform temperature. The comparison of experimental data with theory has been carried out considering direct relations between normalized microwave temperatures and roughness parameters, and by analyzing the effect of roughness on the relation between L band emission and soil moisture.