Thermal Microwave Emission from a Three-Layer Random Medium with Three-Dimensional Variations

The radiative transfer theory has been used to study the thermal microwave emission from a three-layer random medium. The random medium is characterized by correlation functions that are Gaussian in the horizontal direction and exponential in the vertical direction. Gaussian quadrature methods are used to solve for the brightness temperatures. The spectral and angular dependence of the brightness temperature are illustrated numerically. In particular we compare the case of a two-layer random medium whose brightness temperature decreases with frequency with the case of a three-layer random medium whose brightness temperature increases with frequency.