Evaluation of the FluorWPS Model and Study of the Parameter Sensitivity for Simulating Solar-Induced Chlorophyll Fluorescence
Evaluation of the FluorWPS Model and Study of the Parameter Sensitivity for Simulating Solar-Induced Chlorophyll Fluorescence
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FluorWPS模型评估及模拟日光叶绿素荧光的参数灵敏度研究
DOI：
10.3390/rs13061091
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发表时间：
2021-03
期刊：
影响因子：
5
通讯作者：
Huang Qiaolin
中科院分区：
文献类型：
--
作者：
Tong Chiming;Bao Yunfei;Zhao Feng;Fan Chongrui;Li Zhenjiang;Huang Qiaolin
太阳诱导的叶绿素荧光（SIF）已被用作区域和全球尺度上植被光合活性的指标。冠层结构影响了SIF在冠层内的辐射传递过程，造成了SIF的角依赖性。解释这些效应的一个常见解决方案是使用基于物理的辐射传输模型。作为第一步，需要利用地真生物和高光谱遥感测量对三维（3D）辐射传输进行综合评估。由于森林模型的复杂性，很少有研究系统地研究冠层结构因子和太阳-目标观测几何形状对SIF的影响。本研究利用加权光子传播方法（Weighted Photon Spread method, FluorWPS）评估了荧光模型在落叶林中模拟光传感器辐射和树冠顶部SIF的能力，并确定了树冠结构因素和太阳目标观测几何形状对落叶林中SIF大小和方向响应的影响。为了评估该模型，首先利用戈达德的激光雷达高光谱和热（g - light）激光雷达数据构建了一个3D森林场景。通过将计算的叶面积指数与实测的叶面积指数进行对比，验证了重建场景的可靠性，相对误差为3.5%。然后，通过将模拟的at-sensor辐射光谱与HyPlant的DUAL和FLUO光谱仪测量的光谱进行比较，对FluorWPS的性能进行了评估。荧光wps模拟的辐射光谱与两台高性能成像光谱仪的实测光谱吻合较好，决定系数（R2）分别为0.998和0.926。氟wps模型模拟的SIF与DART模型的值吻合较好。此外，还对冠层结构参数和太阳-目标观测几何形状对SIF的影响进行了敏感性分析。在685 nm和740 nm波段，不同叶面积体积密度（fads）对总SIF的最大差异可达45%和47%，植被覆盖度（fvc）对总SIF的最大差异可达48%和46%。叶片角度分布对SIF的大小有显著影响，其发射部分与SIF的比值在0.48 ~ 0.72之间。即使对于茂密的林冠层（植被覆盖度= 3.5 m−1，植被覆盖度= 76%），来自树下草层的SIF对冠层顶部SIF的贡献也超过10%以上。波长为685 nm的红色SIF与波长为740 nm的远红色SIF形状相似，但在不同的照明条件下具有更高的可变性。将FluorWPS模型与LiDAR建模相结合，可以大大提高不同尺度和角度配置下SIF的解释。
Solar-induced chlorophyll fluorescence (SIF) has been used as an indicator for the photosynthetic activity of vegetation at regional and global scales. Canopy structure affects the radiative transfer process of SIF within canopy and causes the angular-dependencies of SIF. A common solution for interpreting these effects is the use of physically-based radiative transfer models. As a first step, a comprehensive evaluation of the three-dimensional (3D) radiative transfers is needed using ground truth biological and hyperspectral remote sensing measurements. Due to the complexity of forest modeling, few studies have systematically investigated the effect of canopy structural factors and sun-target-viewing geometry on SIF. In this study, we evaluated the capability of the Fluorescence model with the Weighted Photon Spread method (FluorWPS) to simulate at-sensor radiance and SIF at the top of canopy, and identified the influence of the canopy structural factors and sun-target-viewing geometry on the magnitude and directional response of SIF in deciduous forests. To evaluate the model, a 3D forest scene was first constructed from Goddard’s LiDAR Hyperspectral and Thermal (G-LiHT) LiDAR data. The reliability of the reconstructed scene was confirmed by comparing the calculated leaf area index with the measured ones from the scene, which resulted in a relative error of 3.5%. Then, the performance of FluorWPS was evaluated by comparing the simulated at-sensor radiance spectra with the spectra measured from the DUAL and FLUO spectrometer of HyPlant. The radiance spectra simulated by FluorWPS agreed well with the measured spectra by the two high-performance imaging spectrometers, with a coefficient of determination (R2) of 0.998 and 0.926, respectively. SIF simulated by the FluorWPS model agreed well with the values of the DART model. Furthermore, a sensitivity analysis was conducted to assess the effect of the canopy structural parameters and sun-target-viewing geometry on SIF. The maximum difference of the total SIF can be as large as 45% and 47% at the wavelengths of 685 nm and 740 nm for different foliage area volume densities (FAVDs), and 48% and 46% for fractional vegetation covers (FVCs), respectively. Leaf angle distribution has a markedly influence on the magnitude of SIF, with a ratio of emission part to SIF range from 0.48 to 0.72. SIF from the grass layer under the tree contributed 10%+ more to the top of canopy SIF even for a dense forest canopy (FAVD = 3.5 m−1, FVC = 76%). The red SIF at the wavelength of 685 nm had a similar shape to the far-red SIF at a wavelength of 740 nm but with higher variability in varying illumination conditions. The integration of the FluorWPS model and LiDAR modeling can greatly improve the interpretation of SIF at different scales and angular configurations.
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影响因子：
13.5
作者：
Gitelson, AA;Buschmann, C;Lichtenthaler, HK
通讯作者：
Lichtenthaler, HK
DOI：
10.1109/36.508411
发表时间：
1996
期刊：
IEEE Trans. Geosci. Remote. Sens.
影响因子：
--
作者：
P. North
通讯作者：
P. North
影响因子：
11.6
作者：
Zhaoying Zhang;Yongguang Zhang;J. Joiner;M. Migliavacca
通讯作者：
Zhaoying Zhang;Yongguang Zhang;J. Joiner;M. Migliavacca
影响因子：
5.2
作者：
Kohler, Philipp;Frankenberg, Christian;Landgraf, Jochen
通讯作者：
Landgraf, Jochen
影响因子：
6.2
作者：
S. Tao;Q. Guo;Le Li;Baolin Xue;M. Kelly;Wenkai Li;Guangcai Xu;Yanjun Su
通讯作者：
S. Tao;Q. Guo;Le Li;Baolin Xue;M. Kelly;Wenkai Li;Guangcai Xu;Yanjun Su