Dependence of Microwave Brightness Temperature on Bistatic Surface Scattering: Model Functions and Application to AMSU-A

摘要: For significant surface reflection, the brightness temperature above planetary surfaces depends not only on temperature, emissivity, and atmospheric emission, but also type of bistatic scattering. a plane-parallel atmosphere, this dependence can be specified by an effective incidence angle thetaseff from zenith downwelling radiation. We obtained analytic expressions for reflectivity typical scattering functions such as Lambert, Lommel-Seeliger, multiple isotropic (Chandrasekhar), Peake's grass model. In all cases, decreases with increasing opacity (considered range: 0 to 1), in most observation direction is small. These results are contrast specular where given angle, which is, course, independent opacity. The terrestrial polar-region temperatures was studied advanced microwave sounding unit-A (AMSU-A). difference between upwelling calculated diffuse greatest opacities range 0.3 0.6, it emissivity. A potential exists infer parameter AL describing relative contributions Lambertian (AL = 1) 0) Some non-Lambertian give values > 1. example, Lommel-Seeliger that observed near vertical about 1.2, still larger (1.6) model Peake. AMSU-A measurements vicinity Dome C, Antarctica, agrees Lambert