ω-τ model uses microwave remote sensing to retrieve soil moisture,ignoring multi-scattering effect inside vegetation layer. In order to make up the limitation of ω-τ model,a algorithm Matric Doubling based on ray tracing technique is proposed to analyse the multi-scattering between vegetation and surface. But the parameters needed in the algorithm are too many and complex, so it is difficult to apply the algorithm to the calculation of soil moisture. The purpose of this paper is to simplify Matric Doubling algorithm. This paper simulates one-order scattering, two-order scattering and multi-scattering respectively with culpa trees' parameters from field expriment. There is little difference between the results of original model and two-oder scattering model.%针对被动微波反演土壤水分中,ω-τ模型忽略植被内部多次散射的局限,将光线跟踪原理的双矩阵(Matrix Doubling)算法应用到植被覆盖地区的地表辐射以及植被与地表之间多次散射问题.这种方法可以有效地弥补ω-τ模型的缺陷,但需要的参数较多且形式复杂,很难被直接应用到模拟计算和土壤水分反演中.针对这些问题,本文将基于双矩阵(Matrix Doubling)的算法进行简化,分别考虑植被内仅存在一次散射、两次散射、三次散射以及多次散射的情况.将散射矩阵和传输矩阵表达式简化,利用野外楸树林实验得到的植被参数进行模拟.结果显示当仅考虑两次散射时模拟结果与原始模型的差别已经很小.
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