多频段微波辐射计对农作物热辐射的遥感和分层随机介质辐射传输的数值模拟

Remote Sensing of Crops by Multi-Frequency MicrowaveRadiometers and Numerical Modeling of RadiativeTransfer of Multi-Layer Random Media

本文给出了用多频段微波辐射计(3.09,5.4,9.6,36GHz)于1990年9月对长春净月潭遥感实验站地区的水稻、大豆等农作物微波热辐射的一些测量结果;发展了多层随机介质辐射传输的理论模式,得出了矢量辐射传输方程的数值解;定量地讨论了农作物微波热辐射的特征及其与各物理参数之间的函数对应关系。

Since 1987 the thermal emission from crop canopies has been measured by multi-frequency microwave radiometers designed by Changchun Institute of Geography, Academia Sinica. The relationship between dualpolarized brightness temperature and some related parameters, such as crop height, moisture content, geometric structure, etc., has been experimentally obtained. To quantitatively understand the functional dependence of brightness temperature on those parameters and frequency, polarization, observation angle, we have developed a numerical modeling of radiative transfer for multi-layer random media, which modeled the stratified layers of fruit, leaves and stalks. The newly-derived dual-dispersion model and Polder Van/de Loor formulation are used to calculate the mean dielectric permittivity. All parameters are chosen in a consistent way. The radiative transfer equation for multi-layer random media is derived. By using the discrete-ordinate and eigen analysis methods, numerical results of radiative transfer are obtained, and are favorably compared with the experimental data. The functional relationship between the brightness temperature and various parameters are discussed.