数据驱动SIF反演算法在塔基观测中的应用效果评价

Performance of Data-driven Algorithm for SIF Retrieval from Tower-based Observation

日光诱导叶绿素荧光(Solar-Induced Chlorophyll Fluorescence,SIF)与植被光合作用关系密切,能够揭示植被真实生理状况,准确获取SIF信息对陆地生态碳循环和全球植被监测具有重要意义。以3FLD算法的SIF反演结果和NIRvR为参考,开展了基于塔基平台的数据驱动SIF反演算法性能评价研究。首先利用塔基连续冠层光谱观测数据,分析了SVD算法在不同大气窗口的SIF反演效果;其次利用大气校正前后的实测数据,探究大气因素对SVD算法反演SIF的影响程度;最后,将实测数据按照光照条件区分,对比了天气稳定与天气波动条件下,基于SVD算法的SIF反演结果的稳定性。结果表明:(1)SVD算法在735~759 nm(不包含大气吸收波段)、745~780 nm(包含大气吸收波段)窗口的SIF反演精度较高;(2)SVD算法的SIF反演精度受大气影响远小于3FLD算法;(3)当光照条件剧烈变化时,使用SVD算法可以有效克服FLD类SIF反演算法对同步太阳光谱观测的依赖;即使光照迅速变化,基于SVD算法依旧能够得到稳定可靠的SIF反演结果。综上所述,SVD算法对于塔基SIF反演来说具有非常大的应用潜力。

Solar-Induced Chlorophyll Fluorescence(SIF)is closely related to vegetation photosynthesis and can reveal the true physiological status of vegetation.Accurate acquisition of SIF information is of great significance for terrestrial ecological carbon cycle and global vegetation monitoring.In this study,taking the SIF retrieval re⁃sults of the 3FLD algorithm and NIRvR as references,the performance evaluation of data-driven SIF retrieval algorithm based on tower-based platform was carried out.Firstly,the SIF retrieval effect of the SVD algorithm in different atmospheric windows was analyzed by using the tower-based spectral observation data.Secondly,using the measured data before and after atmospheric correction,we explored the influence of atmospheric fac⁃tor on the retrieval of SIF by SVD algorithm.Finally,the measured data are distinguished according to the light⁃ing conditions,and the stability of the SIF retrieval results based on the SVD algorithm is compared under the conditions of stable weather and fluctuating weather.The results show that:(1)The SVD algorithm has higher SIF retrieval accuracy in the 735~759 nm(excluding the atmospheric absorption band)and 745~780 nm(in⁃cluding the atmospheric absorption band)windows.(2)The SIF inversion accuracy of the SVD algorithm is much less affected by the atmosphere than the 3FLD algorithm.(3)When the illumination conditions change drastically,the use of SVD algorithm can effectively overcome the dependence of FLD-type SIF retrieval algo⁃rithm on synchronous solar spectrum observation;even if the illumination changes rapidly,a stable and reliable SIF retrieval result can still be obtained based on the SVD algorithm.In summary,the SVD algorithm has great application potential for tower-base SIF retrieval.