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摘要： 日光诱导叶绿素荧光(SIF)是一种植物光合作用直接探测新方法。目前O2-A和O2-B吸收线波段的叶绿素荧光填充效应被广泛应用于探测近红外(760 nm)和红光波段(687 nm)的植被冠层SIF信号。SIF光谱范围为650~800 nm，虽然水吸收波段(719 nm)介于叶绿素荧光发射峰值690 nm和740 nm之间，且具备较强的光谱吸收特征，但该水汽吸收光谱特征尚未应用于冠层SIF探测，因此，基于模型模拟和野外实验观测数据，使用夫琅禾费暗线SIF反演法，评价了基于719 nm 波段水吸收波段的SIF反演潜力，其中野外光谱数据采用ASD FieldSpec Pro便携式地物光谱仪(3 nm分辨率)测量。首先，利用FLD、3FLD、iFLD等3种经典的SIF反演方法，检验和对比分析了719水汽吸收波段的SIF反演性能，结果表明使用水吸收线比使用O2-B吸收线表现更优，反演RMSE为0.154 W/m2/μm/sr。其次，定量计算了水汽和氧气吸收波段SIF反演的敏感度和不确定性，结果表明，719水汽吸收波段与O2-B吸收线相比，其吸收线内外的反射率和荧光比值估算误差对SIF反演误差的贡献更小，但是显大于比02-A波段。最后，利用野外多角度和日变化观测实验数据，检验和分析了三个大气吸收波段的SIF反演结果，发现719 nm水吸收波段的冠层SIF与 O2-A和O2-B 氧气吸收波段具有相似的角度变化和日变化特征，表现为后视和热点方向的SIF高、前视和暗点方向的SIF低，以及中午SIF高、早晚SIF低。研究表明利用719 nm 波段的水汽吸收波段的光谱信息，可以准确反演近地面冠层SIF信号，研究结果为近地面冠层SIF 观测提供了一个新的波段。   Abstract: In the visible and near-infrared region，at a spectral resolution of 1 nm，the solar irradiance spectrum exhibits four absorption features:the HαFraunhofer line (656.4 nm)，H2O absorption at 719 nm，the O2-B (687 nm) and O2-A (761 nm) bands.Although the H2O band is located between the chlorophyll fluorescence emission peaks at about 690 and 740 nm，it has never been investigated for SIF retrieval.In this paper，the potential of the H2O absorption band at 719 nm for SIF retrieval is investigated using different Fraunhofer line discrimination (FLD) methods based on the FluorMOD simulations and field data taken by an ASD FieldSpec Pro spectrometer (3 nm resolution).Firstly，the SIF retrieval performance using the H2O band was examined with different FLD methods at a spectral resolution of 1 nm.the results obtained using the HO band are better than for the O2-B band，and the associated RMSE is 0.154 W/m2/μm/sr.Then，the sensitivities and uncertainties of the SIF retrieval using the improved FLD (iFLD) method were calculated for the three atmospheric absorption bands.the total SIF estimation error and its contribution to the theoretical error in the two correction coefficients are found to be smaller using the H2O band than using the O2-B band，but significantly larger than that achieved using the O2-A band.Finally，the SIF retrieval using the iFLD method in the three atmospheric absorption bands is also examined in a field experiment.the SIF retrieval using the H2O band at 719 nm is found to have a similar performance to that using the O2-B and O2-A bands at canopy level.Finally，the SIF retrievals using the iFLD method in the three atmospheric absorption bands were also examined using field experiments.the SIF retrievals using the H2O band at 719 nm are similar to those at O2-A and O2-B oxygen absorption band，showing high values in backward and hot-spot directions and low values in forward and dark directions，and high SIF values at noon and low SIF in the morning and afternoon.Therefore，the H2-O absorb band provides a new band for retrieval of canopy SIF at near-ground platform.

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