Evaluation of the FluorWPS Model and Study of the Parameter Sensitivity for Simulating Solar-Induced Chlorophyll Fluorescence

Solar-induced chlorophyll fluorescence (SIF) has been used as an indicator for the photosynthetic activity of vegetation at regional and global scales. Canopy structure affects radiative transfer process SIF within canopy causes angular-dependencies SIF. A common solution interpreting these effects is use physically-based models. As a first step, comprehensive evaluation three-dimensional (3D) transfers needed using ground truth biological hyperspectral remote sensing measurements. Due to complexity forest modeling, few studies have systematically investigated effect structural factors sun-target-viewing geometry on In this study, we evaluated capability Fluorescence model with Weighted Photon Spread method (FluorWPS) simulate at-sensor radiance top canopy, identified influence magnitude directional response in deciduous forests. To evaluate model, 3D scene was constructed from Goddard’s LiDAR Hyperspectral Thermal (G-LiHT) data. The reliability reconstructed confirmed by comparing calculated leaf area index measured ones scene, which resulted relative error 3.5%. Then, performance FluorWPS simulated spectra DUAL FLUO spectrometer HyPlant. agreed well two high-performance imaging spectrometers, coefficient determination (R2) 0.998 0.926, respectively. values DART model. Furthermore, sensitivity analysis conducted assess parameters maximum difference total can be large 45% 47% wavelengths 685 nm 740 different foliage volume densities (FAVDs), 48% 46% fractional covers (FVCs), Leaf angle distribution markedly SIF, ratio emission part range 0.48 0.72. grass layer under tree contributed 10%+ more even dense (FAVD = 3.5 m−1, FVC 76%). red wavelength had similar shape far-red but higher variability varying illumination conditions. integration modeling greatly improve interpretation scales angular configurations.