【摘要】 本文采用多频段(1.4,5.4,9.2,36GHz)微波辐射计测量了不同湿度土壤的微波辐射亮度温度。应用非均匀温度湿度廓线的耗散介质的起伏逸散定理和WKB法,进行了理论模式的数值计算,并和实验结果取得了很好的一致。还对极重函数、非均匀廓线和其它参数作了定量的灵敏度分析。更多还原

【Abstract】 Since 1977 microwave brightness temperature of wet soil have been measured by multi-frequency (1.4, 5.4, 9.2 and 36 GHz) radiometer designed by Changchun Institute of Geography, Academia Sinica. The relationship between dualpolarized brightness temperature and soil moisture has been experimentally obtained. In numerical simulation, wet soil was modeled as stratified, half-space dissipated media. By using the dyadic Green’s function of stratified media and the fluctuation-dissipation theorem, thermal radiance from such media may be calculated. However, in the previous approaches of the fluctuation dissipation and radiative transfer, the functional dependence of practical soil dielectric profile with soil temperature, wetness, soil structure and so on were lacking. By employing the empirical formulation of multi-phase mixture for soil dielectric profile, and applying the fluctuation dissipation approach in WKB method, we developed a numerical model to simulate the brightness temperature versus soil surface wetness, frequency, observation angle, etc.. Our numerical results are shown to agree well with multi-frequency data measured in our Jing Yu Tang Remote Sensing Site. We also discuses in this paper the contribution from weighting function in radiative transfer at different depth for multi-frequency, and the effects due to wetness and temperature profiles, polarization, and observation angle. It does show quantitatively the functional dependence of brightness temperature on these conditions. Sensitivity of some parameters, such as wetness transition which is closely related with soil structure, is also tested.更多还原