太阳诱导叶绿素全波段连续荧光光谱遥感探测机理与方法研究

The emission spectrum of solar-induced vegetation chlorophyll fluorescence (SIF) mainly occurs within the 650-800 nm spectral region, characterizing both intensity and shape information. Quantitative remote retrieval of the continuous SlF spectrum at large scales will play a vital role in monitoring of global vegetation and carbon cycle. However, most of current passive remote retrieval methods (e.g., FLD series methods) of SIF depend on the Fraunhofer lines as well as nearby limited reference bands, resulting in that only one or a few SlFs at Fraunhofer lines could be estimated. As a result, a lot of useful information for vegetation monitoring will be missing. To address the issue, using simulation and field hyperspectral data, the mechanisms of SIF retrieval algorithms will be investigated. On this basis, optimal fitting technologies for full-band vegetation reflectance and fluorescence spectra will be explored, and then remotely sensed models for continuous full-band SIF spectrum will be developed. This proposal will lay the foundations for the promotion of the application capability of chlorophyll fluorescence and for future novel fluorescence satellite sensors, due to enabling the entire SIF spectrum estimation from the reflected flux.

植被叶绿素受太阳光诱导后发射的荧光主要在650-800nm范围，是一条兼具强度和形状信息的连续光谱。从遥感大尺度探测这一荧光光谱，对于全球植被监测及碳循环研究具有重要意义。然而，目前荧光被动遥感算法（如FLD系列算法）大都依赖于大气吸收暗线及其前后少量的参考波段，而只能探测单一或少数波段的荧光，导致丢失了大量对植被监测有用的信息。针对这一问题，本项目拟联合模型模拟与地面实测超光谱数据，深入研究太阳诱导叶绿素荧光遥感探测算法机理，探索基于全波段信息的反射率与荧光光谱最优拟合原理与方法，构建全波段连续的荧光光谱遥感探测模型，解决从遥感反射中提取完整叶绿素荧光光谱（650-800nm）的难题，为太阳诱导叶绿素荧光应用能力的提升和未来新型荧光遥感卫星载荷的设计奠定基础。

针对目前主流被动遥感探测算法难以获取全波段连续的叶绿素荧光光谱的问题，本项目系统总结分析了当前太阳诱导叶绿素荧光（SIF）遥感反演思路与方法；在此基础上，开展了SIF遥感探测算法机理研究，以及SIF与反射辐射（冠层结构效应）相互影响机制研究；定量分析了影响全波段不同反演窗口算法模型的关键敏感因子（如荧光波形函数等），深入开展了基于全波段信息的FLD原理算法改进和基于数据驱动的连续荧光谱反演机理与算法优化研究，确定了基于数据驱动的全波段荧光反演模型参数的设置与获取方法；最后，采用不同的数据源与方案对本项目算法模型进行了综合评估与验证。本项目取得的研究成果已服务于我国首颗林业碳卫星荧光载荷（预计2020年发射）型号工程论证，国家林业局组织专家评审认为研究可为我国首颗林业碳卫星荧光载荷的产品生产及应用等提供技术支持。