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    于颖, 刘敏, 范文义, 卫甜甜, 程腾辉, 蒋博, 张月. 基于PROSPECT和4-scale模型的光化学植被指数尺度转换[J]. 北京林业大学学报, 2020, 42(10): 27-35. DOI: 10.12171/j.1000-1522.20190190
    引用本文: 于颖, 刘敏, 范文义, 卫甜甜, 程腾辉, 蒋博, 张月. 基于PROSPECT和4-scale模型的光化学植被指数尺度转换[J]. 北京林业大学学报, 2020, 42(10): 27-35. DOI: 10.12171/j.1000-1522.20190190
    Yu Ying, Liu Min, Fan Wenyi, Wei Tiantian, Cheng Tenghui, Jiang Bo, Zhang Yue. Scale conversion of photochemical reflectance index based on PROSPECT and 4-scale models[J]. Journal of Beijing Forestry University, 2020, 42(10): 27-35. DOI: 10.12171/j.1000-1522.20190190
    Citation: Yu Ying, Liu Min, Fan Wenyi, Wei Tiantian, Cheng Tenghui, Jiang Bo, Zhang Yue. Scale conversion of photochemical reflectance index based on PROSPECT and 4-scale models[J]. Journal of Beijing Forestry University, 2020, 42(10): 27-35. DOI: 10.12171/j.1000-1522.20190190

    基于PROSPECT和4-scale模型的光化学植被指数尺度转换

    Scale conversion of photochemical reflectance index based on PROSPECT and 4-scale models

    • 摘要:
        目的  光化学植被指数(PRI)对于准确估计植被光能利用率(LUE)有着重要的作用。但在不同的尺度(叶片、冠层、景观尺度)上,PRI与LUE二者之间的关系及其影响因素不同。传感器获得的光谱为像元及冠层光谱,叶片尺度的PRI-LUE关系模型无法直接用于冠层尺度的数据,因此需要对冠层尺度的PRI指数进行尺度转换。
        方法  首先通过叶片尺度的PROSPECT模型,模拟不同生化参数下叶片的反射率与透射率,进而计算叶片尺度PRI指数与简单比值PRI指数(记为SR-PRI)。其次,将获得的叶片尺度反射率、透射率作为参数输入到4-scale模型中,获取不同叶面积指数( LAI)下冠层尺度的反射率,计算得出冠层尺度的PRI、SR-PRI。建立不同LAI下PRI、SR-PRI的冠层−叶片尺度转换函数,并对不同尺度上影响PRI、SR-PRI的因子进行敏感性分析。
        结果  PRI、SR-PRI在进行冠层与叶片尺度转化过程中,都表现出很明显的线性关系,并且拟合效果(R2)呈现出随LAI的增大而增大的趋势。对比相同LAI水平下的PRI、SR-PRI的拟合结果发现,SR-PRI的拟合效果普遍要优于PRI。
        结论  4-scale模型用来进行PRI与SR-PRI在冠层、叶片间的尺度转换是可行的,通过建立不同LAI下的尺度转换函数,可以实现将冠层尺度的PRI、SR-PRI转化到叶片尺度。

       

      Abstract:
        Objective  Photochemical reflectance index (PRI) plays an important role in accurately estimating photosynthetic light use efficiency (LUE). However, at different levels, such as leaf, canopy and landscape levels, the relationship between PRI and LUE and their influencing factors are different. The spectra obtained by the sensor are pixel and canopy spectra. The PRI-LUE relationship model of the leaf level cannot be directly used for canopy-level data. Therefore, the canopy level PRI needs to be scale-converted to obtain the leaf level PRI.
        Method  In this paper, the leaf-level PROSPECT model was used to simulate the reflectance and transmittance of the leaves considering different biochemical parameters, and then the leaf-level PRI and the simple ratio PRI (denoted as SR-PRI) were calculated. Secondly, the obtained leaf-level reflectance and transmittance were input as parameters to 4-scale model to get canopy reflectance under different LAIs, and the canopy-level PRI and SR-PRI were calculated. Finally, the regression analysis of PRI and SR-PRI in canopy and leaf level was carried out under different LAIs. The sensitivity of the influencing factors on PRI and SR-PRI at different scales was analyzed.
        Result  PRI and SR-PRI of the canopy level have a good linear relationship with that of the leaf level. SR-PRI is generally better than PRI at the relationship of both levels, and the coefficients R2 is positively correlated with LAI.
        Conclusion  The 4-scale model is feasible for scale conversion between canopy and leaf for PRI and SR-PRI. Canopy level PRI and SR-PRI can be transformed to leaf level by the functions established at different LAIs efficiently.

       

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