Reconstruction of the full spectrum of solar-induced chlorophyll fluorescence: Intercomparison study for a novel method
Reconstruction of the full spectrum of solar-induced chlorophyll fluorescence: Intercomparison study for a novel method
复制标题
重建太阳诱导叶绿素荧光的全光谱：一种新方法的比对研究
DOI：
10.1016/j.rse.2018.10.021
复制
发表时间：
2018-12
影响因子：
13.5
通讯作者：
Jianxi Huang
中科院分区：
文献类型：
--
作者：
Feng Zhao;Rong Li;Wout Verhoef;Sergio Cogliati;Xinjie Liu;Yanbo Huang;Yiqing Guo;Jianxi Huang
太阳诱导的叶绿素荧光(SIF)与植物的光合作用活动密切相关，可以作为植被功能和状态的早期非侵入性指标。大多数现有的方法在很少的离散吸收线附近提取SIF。然而，完整的SIF光谱可以提供有关光合作用机械功能状态的更多信息。欧洲航天局将于2022年发射的荧光探测器(FLEX)任务致力于精确重建陆地上的全SIF光谱，并将两个SIF峰的高度和位置以及总荧光发射(光谱积分值)纳入计划的二级产品中。本文提出了一种改进的荧光光谱重建方法(AFSR)，利用现有方法的特点重建SIF全光谱。AFSR方法使用基光谱的线性组合来逼近SIF的光谱和反射因子，并利用SIF发射光谱范围内的所有可用波段对SIF和反射辐射进行光谱拟合。基于贝叶斯信息准则，自适应地确定了反射系数的基谱个数。利用模拟和实验数据集对aFSR方法和其他三种方法(即荧光光谱重建法、全光谱拟合法和specFit法)进行了全面的比较。对于模拟数据集，考虑了光谱分辨率(SR)、信噪比(SNR)、大气校正、冠层结构、叶片生化参数和方向效应对SIF光谱重建精度的影响。结果表明，当光谱分辨率和信噪比较高时(如SR ≤ 0.3 nm和SNR ≥ 70 0)，虽然所有方法都能达到FLEX任务设定的精度标准(光谱集成SIF的平均绝对相对误差为10%)，但aFSR重建精度最高。首次研究了SIF谱重构在三维辐射传输(RT)模拟中的性能，并与典型的一维模拟结果进行了比较。冠层异质性从一维增加到三维并没有明显降低aFSR的精度，这意味着aFSR适用于不同的冠层结构。与其他方法相比，aFSR方法受大气改正和方向效应的影响较小，因此具有更强的鲁棒性。在实验数据集上，aFSR重建的应力强度因子谱在形状、大小和日变化方面与文献报道吻合较好，并与其他方法相一致：aFSR重建结果与其他三种方法重建的应力强度因子谱的平均值之间的决定系数和均方根误差分别大于0.93和小于0.09 W·m−2·sr−1·μm−1。
Solar-Induced chlorophyll Fluorescence (SIF) can serve as an early and non-invasive indicator of the functioning and status of vegetation due to its close link to photosynthetic activity. Most existing approaches retrieve SIF at around few discrete absorption lines. However, the full SIF spectrum can provide more information on the functional status of photosynthetic machinery. European Space Agency's FLuorescence EXplorer (FLEX) mission, to be launched in 2022, is dedicated to the accurate reconstruction of the full SIF spectrum over land and incorporates the heights and positions of the two SIF peaks and the total fluorescence emission (spectrally-integrated value) into planned Level-2 products.In this paper, an advanced Fluorescence Spectrum Reconstruction (aFSR) method was proposed to reconstruct the full SIF spectrum by capitalizing on the features of existing methods. The aFSR method used linear combinations of basis spectra to approximate the spectra of SIF and the reflectance factor and exploited all available bands within the spectral range of SIF emission for spectral fitting of SIF and reflected radiance. The number of basis spectra of the reflectance factor used was self-adaptively determined based on the Bayesian information criterion. A comprehensive intercomparison between the aFSR method and three other methods (i.e., the Fluorescence Spectrum Reconstruction method, the Full-spectrum Spectral Fitting Method, and the SpecFit method) was performed using simulated and experimental datasets. For simulated datasets, the impact of spectral resolution (SR), signal-to-noise ratio (SNR), atmospheric correction, canopy structure, leaf biochemical parameters and directional effect on the accuracy of SIF spectrum reconstruction was considered. Results show that while all methods could achieve the accuracy standard set by the FLEX mission (average absolute relative error of spectrally-integrated SIF <10%) when spectral resolving power and SNR were high (e.g., SR ≤ 0.3 nm and SNR ≥ 700), aFSR generally provided the highest reconstruction accuracy. For the first time we investigated the performance of the SIF spectrum reconstruction on 3-D radiative transfer (RT) simulations and compared with that on typical 1-D simulations. The increase of canopy heterogeneity from 1-D to 3-D did not noticeably deteriorate the accuracy of aFSR, implying that aFSR was applicable to different canopy structures. The aFSR method was also more robust than other methods as it was less affected by atmospheric correction and directional effect. For the experimental dataset, the SIF spectra reconstructed by aFSR agreed well with literature in terms of shape, magnitude and diurnal variation and were in agreement with the other methods: the coefficient of determination and the root-mean-square error between the reconstruction results of aFSR and the average of the SIF spectra reconstructed through three other methods were higher than 0.93 and lower than 0.09 W·m−2·sr−1·μm−1, respectively.
登录
查看更多内容
影响因子：
4.3
作者：
Agati, G;Mazzinghi, P;Cecchi, G
通讯作者：
Cecchi, G
影响因子：
5.2
作者：
Rossini, M.;Nedbal, L.;Rascher, U.
通讯作者：
Rascher, U.
影响因子：
5
作者：
Coppo, Peter;Taiti, Alessio;Drusch, Matthias
通讯作者：
Drusch, Matthias
影响因子：
11.6
作者：
Zhang, Yongguang;Guanter, Luis;Koehler, Philipp
通讯作者：
Koehler, Philipp
影响因子：
8.9
作者：
Shari Van Wittenberghe;L. Alonso;J. Verrelst;I. Hermans;J. Delegido;Frank Veroustraete;R. Valcke;J. Moreno;R. Samson
通讯作者：
Shari Van Wittenberghe;L. Alonso;J. Verrelst;I. Hermans;J. Delegido;Frank Veroustraete;R. Valcke;J. Moreno;R. Samson