Passive Microwave Remote Sensing of an Anisotropic Random-Medium Layer

The principle of reciprocity is invoked to calculate the brightness temperatures for passive microwave remote sensing of a twolayer anisotropic random medium. The bistatic scattering coefficients are first computed with the Born approximation and then integrated over the upper hemisphere to be subtracted from unity, in order to obtain the emissivity for the random-medium layer. The theoretical results are illustrated by plotting the emissivities as functions of viewing angles and polarizations. They are used to interpret remote sensing data obtained from vegetation canopy where the aniostropic randommedium model applies. Field measurements with corn stalks arranged in various configurations with preferred azimuthal directions are successfully interpreted with this model.