Abstract

A Monte Carlo-based three-dimensional radiative transfer model has been developed to describe the reflection and scattering of solar radiation within a spatially heterogeneous plant canopy. In the model the plant canopy is considered as a group of trees with a similar spatial structure, modeled using fractal geometry. The architecture of an individual tree is described using its height, the number and length of branches of different orders, the angle of inclination of the branches, and the number of leaves. To describe the spatial patterns of solar radiation within a non-uniform plant canopy, the contribution of each model ‘‘photon’’ is calculated in the model taking its interaction and possible multiple reflection on vegetation elements and the soil surface based on the Lambert’s law into account. Possible directions of photon propagation were determined according to the 9th order Gauss-Markov quadrature formulas. The results of numerical experiments for the case of the solar radiation interaction with an individual tree have shown that the model adequately describes the spatial heterogeneity of reflected and transmitted direct solar radiation.

中文翻译：

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蒙特卡罗方法在林冠太阳辐射反射与透射建模中的应用

摘要

已开发出基于蒙特卡洛的三维辐射传递模型，以描述空间异质植物冠层内太阳辐射的反射和散射。在模型中，植物冠层被视为一组具有类似空间结构的树木，并使用分形几何进行建模。使用其高度，不同阶数的分支的数量和长度，分支的倾斜角度以及叶子的数量来描述单个树的体系结构。为了描述不均匀植物冠层中太阳辐射的空间格局，根据兰伯特定律，在模型中考虑了每个模型“光子”的相互作用以及对植被元素和土壤表面的可能多次反射，从而计算了模型“光子”的贡献。考虑在内。光子传播的可能方向是根据9阶高斯-马尔可夫正交公式确定的。在太阳辐射与一棵单独的树木相互作用的情况下的数值实验结果表明，该模型充分描述了反射和透射的直接太阳辐射的空间异质性。