日光诱导叶绿素荧光是植被光合作用遥感监测的有力工具，荧光的精确观测与反演是其应用研究的基础保障，但目前的荧光遥感反演算法还存在诸多不确定性。项目将聚焦植被二向反射特征对叶绿素荧光遥感反演的影响这一有待解决的科学问题，研究植被BRDF效应与叶绿素荧光在氧气吸收波段的耦合机制，阐明植被BRDF效应对氧气吸收波段虚假“填充”效应的产生机理，研究植被直射光/漫射光反射率差异、漫射光比例、冠层结构等参数对氧气吸收波段虚假“填充”效应的影响，基于半经验BRDF模型分析优化自然条件下植被直射光/漫射光反射率差异的估算方法，并在此基础上构建植被BRDF效应对荧光反演影响的校正模型。研究成果将可有效改进基于氧气吸收波段的荧光反演精度，为荧光应用研究提供更为准确可靠的数据源。

Solar-induced chlorophyll fluorescence (SIF) has become a powerful tool for the monitoring of photosynthesis by remote sensing. Accurate observation and retrieval of the SIF signal is the basis for the application of SIF. However, there are still lots of uncertainties in the algorithms for SIF retrieval to date. This project will focus on the effect of the canopy bi-directional reflectance on the retrieval of SIF, which is still an unsolved scientific issue. In this project, we will: analyze the interaction between the BRDF effect and the SIF emission at the oxygen absorption band; explain the mechanism of the artificial in-filling effect at the oxygen band by the BRDF effect; analyze the relationship between the in-filling effect and the reflectance of direct/diffuse radiation, the diffuse-to-global radiation ratio, and canopy structure parameters; optimize the methods for the estimation of the difference between the reflectance of direct and diffuse radiation under natural conditions; and hence, establish the correction model for the BRDF effect on the SIF retrieval. The outcomes of the project will be effective on improving the SIF retrieval accuracy at the oxygen absorption band, and will be able to provide more accurate and reliable data source for the application of SIF.