Zhang Yongqi, Liu Xinjie, Du Shanshan, Qi Mengjia, Jing Xia, Liu Liangyun
College of Geomatics, Xi'an University of Science and Technology, Xi'an 710054, China.
International Research Center of Big Data for Sustainable Development Goals, Beijing 100094, China.
Sensors (Basel). 2025 Jan 24;25(3):689. doi: 10.3390/s25030689.
Solar-induced chlorophyll fluorescence (SIF) is essential for monitoring vegetation photosynthesis. The water vapor absorption band, the broadest absorption window, has a deeper absorption line than the O-B band, providing significant potential for SIF retrieval; however, substantial variation in atmospheric water vapor column concentrations limits research on SIF retrieval using this band. This study evaluates seven common SIF retrieval algorithms, including sFLD, 3FLD, iFLD, pFLD, SFM, SVD, and DOAS, using simulated datasets under varying atmospheric water vapor concentrations, spectral resolution (SR), and signal-to-noise ratios (SNRs). Additionally, the SIF retrieval results from the HO, O-B, and O-A absorption bands are compared and analyzed to explore the fluorescence retrieval potential of the water vapor band. Furthermore, the potential of commonly used spectrometers, including Ocean Optics QE Pro and ASD FieldSpec 3, for SIF retrieval using the water vapor absorption band was evaluated. The results were further validated using ground-based tower observations. The results show that sFLD consistently overestimates SIF in the water vapor band, limiting its reliability, while SFM performs best across varying conditions. In comparison, 3FLD and pFLD, along with SVD, are accurate at high resolutions but less effective at lower ones. iFLD performs relatively poorly overall, whereas DOAS excels in low SR retrievals. At the same time, our study also shows that the water vapor band offers higher accuracy in ground-based SIF retrieval compared to the O-B band, demonstrating strong application potential and providing valuable references for selecting SIF retrieval algorithms.
太阳诱导叶绿素荧光（SIF）对于监测植被光合作用至关重要。水汽吸收带是最宽的吸收窗口，其吸收线比O - B带更深，为SIF反演提供了巨大潜力；然而，大气水汽柱浓度的显著变化限制了利用该波段进行SIF反演的研究。本研究使用在不同大气水汽浓度、光谱分辨率（SR）和信噪比（SNR）下的模拟数据集，评估了七种常见的SIF反演算法，包括sFLD、3FLD、iFLD、pFLD、SFM、SVD和DOAS。此外，还对HO、O - B和O - A吸收带的SIF反演结果进行了比较和分析，以探索水汽带的荧光反演潜力。此外，还评估了常用光谱仪（包括海洋光学QE Pro和ASD FieldSpec 3）利用水汽吸收带进行SIF反演的潜力。结果通过地面塔台观测进一步验证。结果表明，sFLD在水汽带中始终高估SIF，限制了其可靠性，而SFM在各种条件下表现最佳。相比之下，3FLD和pFLD以及SVD在高分辨率下准确，但在低分辨率下效果较差。iFLD总体表现相对较差，而DOAS在低SR反演中表现出色。同时，我们的研究还表明，与O - B带相比，水汽带在地面SIF反演中具有更高的精度，具有很强的应用潜力，为选择SIF反演算法提供了有价值的参考。
