Radiative-transfer theory for the remote sensing of layered random media

The radiative-transfer theory for the remote sensing of layered media has been developed with the use of random permittivities to account for scattering effects. Analytical solutions for a three-layer model are discussed for applications to both active and passive remote sensing. Various numerical results are illustrated to show the dependence of the brightness temperature variations on the layer thickness, the variance, the correlation length, and the permittivities. Usually the brightness temperature increases when the loss tangents increase and decreases when the variances and the correlation lengths increase. We also illustrate the case of a homogeneous layer on top of a scattering layer where the brightness temperature increases as a function of frequency and the case of only a scattering layer where brightness temperature decreases as a function of frequency.