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首页> 外文会议>Geoscience and Remote Sensing Symposium, 1995. IGARSS '95. 'Quantitative Remote Sensing for Science and Applications', International >A fully polarimetric multiple scattering model for agricultural fields
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A fully polarimetric multiple scattering model for agricultural fields

机译：农业领域的全极化多重散射模型

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A discrete model has been developed at Tor Vergata University, which describes vegetation as an ensemble of discs and cylinders overlying a homogeneous half-space with a rough interface. The model predicts the backscatter coefficient including multiple scattering effects. The first version, which was based on a scalar approach (2 Stokes components) has now been improved in order to get a fully polarimetric approach (4 Stokes components). Soil scattering is represented, for each pair of incidence and scattering directions, by a 4/spl times/4 scatter matrix, computed by means of the small perturbation approximation (for smooth soils) and the geometrical optics approximation (for rough soils). The vegetation layer is subdivided into many thin layers, each filled with discs and/or cylinders. The scattering and transmission properties of a thin layer are represented, for each pair of incidence and scattering directions, by two 4/spl times/4 scatter matrices (for upper and lower half-spaces respectively) and, for each incidence direction, by a 4/spl times/4 extinction matrix. Matrices are computed by means of Rayleigh-Gans or physical optics approximations, depending on frequency. Finally, the contributions of the various thin layers and that of the soil are combined by means of the matrix doubling algorithm. In this paper, the authors' recent modeling advances are described. In particular, the differences between the scalar approach and the polarimetric approach are emphasized. The polarimetric model results are compared with experimental radar data obtained over agricultural fields of the Italian Montespertoli site during the MAC-91 Campaign. In particular, the crop biomass effects are investigated at L-band in the case of sunflowers. Some polarimetric features, like backscatter coefficients in linear and circular polarizations, and phase difference between VV and HH channels are considered.
机译：Tor Vergata大学开发了一个离散模型，该模型将植被描述为圆盘和圆柱体的集合，这些圆盘和圆柱体覆盖在具有粗糙界面的均匀半空间上。该模型预测包括多个散射效应的后向散射系数。基于标量方法（2个Stokes组件）的第一个版本现已得到改进，以便获得完全极化方法（4个Stokes组件）。对于每对入射和散射方向，土壤散射通过4 / spl次/ 4散射矩阵表示，该矩阵通过小扰动近似值（对于光滑土壤）和几何光学近似值（对于粗糙土壤）来计算。植被层被细分为许多薄层，每个薄层中都充满了圆盘和/或圆柱体。对于每一对入射和散射方向，薄层的散射和透射特性分别由两个4 / spl次/ 4散射矩阵（分别用于上半空间和下半空间）表示，并且对于每个入射方向，均用a表示。 4 / spl倍/ 4消光矩阵。取决于频率，通过瑞利甘斯或物理光学近似来计算矩阵。最后，借助矩阵加倍算法将各种薄层和土壤的贡献结合起来。本文描述了作者最近的建模进展。尤其要强调标量方法与极化方法之间的差异。将极化模型的结果与在MAC-91战役期间在意大利Montespertoli基地的农田上获得的实验雷达数据进行了比较。特别是，在向日葵的情况下，在L波段研究了作物生物量的影响。考虑了一些极化特征，例如线性和圆形极化中的反向散射系数，以及VV和HH通道之间的相位差。

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