四种常用的太阳诱导植被叶绿素荧光 反演方法对比分析研究

Comparative analysis of four commonly used sun-inducedchlorophyll fluorescence retrieval methods

关键词:  太阳诱导叶绿素荧光（SIF）  反演方法  SCOPE  夫琅禾费暗线方法

Key words:  Sun-induced chlorophyll fluorescence（SIF）  retrieval methods  Soil- Canopy-Observation of Photosynthesis and the Energy Balance（SCOPE）  Fraunhofer Line Discrimination（FLD）  Spectral Fitting Method（SFM）

摘要:

【目的】太阳诱导叶绿素荧光（SIF）是一种新型的植被参数，可用于监测植物光合作 用状态和评估总初级生产力。利用模拟数据对比分析常用SIF 反演方法的精度，为野外测量 仪器SIF 反演方法的选择提供理论基础。【方法】选择SCOPE 模型模拟了不同生化理化参数 下的模拟数据，并以该数据为基础生成不同光谱分辨率（SR）和不同信噪比（SNR）下的 模拟数据集。选择4 种常用SIF 反演方法进行SIF 反演：夫琅禾费暗线法（FLD），3FLD、 iFLD 和光谱拟合法（SFM）。【结果】基于模拟数据的反演结果表明SFM 和iFLD 方法能够获 得更准确的SIF，其均方根误差（RMSE）分别为0.1142 W/m2/μm/sr 和0.1114 W/m2/μm/sr； 3FLD 法亦能取得较准确的SIF 结果，其RMSE 为0.2014 W/m2/μm/sr；而FLD 法的精度较差， 其RMSE 大于0.5 W/m2/μm/sr。在高SR 和SNR 条件下，SFM 和iFLD 法明显优于3FLD 和 FLD 法，但随着SR 和SNR 的降低，4 种反演方法的精度也随之降低，其中iFLD 法受SNR 影响最为明显。【结论】利用SFM 和iFLD 方法能够得到更准确的SIF 反演结果，且随着仪 器SR 和SNR 的提高其反演精度也随着提高，但iFLD 方法易受SNR 的影响。因此，对于光 谱分辨率优于1 nm 的测量仪器应优先选择SFM 方法来反演SIF。

Abstract:

［Purpose］Solar-induced chlorophyll fluorescence（SIF）is a novel vegetation parameter that can be used to monitor plant photosynthesis status and assess total primary productivity. The accuracy of the four commonly used SIF retrieval methods is compared and analyzed using simulation data and field measured data，which provides a theoretical basis for the selection of SIF retrieval methods for field measurement instruments.［Method］The SCOPE （Soil-Canopy-Observation of Photosynthesis and the Energy Balance）model was selected to simulate the simulated data sets under different vegetation biochemical and physical parameters. Analog dataset under different resolutions（SR）and different signal-to-noise ratio（SNR）were generated based on the data. Four commonly used SIF retrieval methods were selected to retrieve the SIF：Fraunhofer Line Discrimination（FLD），3FLD（modified FLD），iFLD（improved FLD）and SFM（Spectral Fitting Method）methods.［Result］The retrieval results based on the simulated data show that the SFM and iFLD methods can obtain more accurate SIF results with root mean square error（RMSE）of 0.1142 W/m2/μm/sr and 0.1114 W/m2/μm/sr，respectively. The 3FLD method can also obtain accurate SIF results with an RMSE of 0.2014 W/m2/μm/sr. The accuracy of the FLD method is poor，and its RSME is greater than 0.5 W/m2/μm/sr. Under high SR and SNR conditions，SFM and iFLD algorithms are significantly better than 3FLD and FLD algorithms，but with the decrease of SR and SNR，the accuracy of the four retrieval methods is also reduced，and the iFLD method is most affected by SNR.［Conclusion］The SFM and iFLD methods can obtain more accurate SIF results，and the retrieval accuracy increases with the improvement of SR and SNR，but the iFLD method is susceptible to SNR. Therefore，the SFM method is preferred for spectrometric instruments with spectral resolutions below 1 nm.