Recent advances in remote sensing of solar-induced chlorophyll fluorescence (SIF) have improved the capabilities of monitoring large-scale Gross Primary Productivity (GPP). However, SIF observations are subject to directional effects which can lead to considerable uncertainties in various applications. Practical approaches for normalizing directional SIF observations to nadir viewing, to minimize the directional effects, have not been well studied. Here we developed two practical and physically-solid approaches for removing the directional effects of anisotropic SIF observations: one is based on near-infrared or red reflectance of vegetation (NIRv and Redv), and the other is based on the kernel-driven model with multi-angular SIF measurements. The first approach uses surface reflectance while the second approach directly leverages multi-angular SIF measurements. The performance of the two approaches was evaluated using a dataset of multi-angular measurements of SIF and reflectance collected with a high-resolution field spectrometer over different plant canopies. Results show that the relative mean absolute errors between the normalized nadir SIF and the observed SIF at nadir decrease by 3–6% (far-red) and 6–8% (red) for the first approach, and by 7–13% and 6–11% for the second approach, compared to the original data, respectively. The effectiveness and simplicity of our proposed approaches provide great potential to generate long-term and consistent SIF data records with minimized directional effects.

Hao, D., Zeng, Y., Qiu, H., Biriukova, K., Celesti, M., Migliavacca, M., et al. (2021). Practical approaches for normalizing directional solar-induced fluorescence to a standard viewing geometry. REMOTE SENSING OF ENVIRONMENT, 255(15 March 2021) [10.1016/j.rse.2020.112171].

Practical approaches for normalizing directional solar-induced fluorescence to a standard viewing geometry

Biriukova K.;Celesti M.;Rossini M.;
2021

Abstract

Recent advances in remote sensing of solar-induced chlorophyll fluorescence (SIF) have improved the capabilities of monitoring large-scale Gross Primary Productivity (GPP). However, SIF observations are subject to directional effects which can lead to considerable uncertainties in various applications. Practical approaches for normalizing directional SIF observations to nadir viewing, to minimize the directional effects, have not been well studied. Here we developed two practical and physically-solid approaches for removing the directional effects of anisotropic SIF observations: one is based on near-infrared or red reflectance of vegetation (NIRv and Redv), and the other is based on the kernel-driven model with multi-angular SIF measurements. The first approach uses surface reflectance while the second approach directly leverages multi-angular SIF measurements. The performance of the two approaches was evaluated using a dataset of multi-angular measurements of SIF and reflectance collected with a high-resolution field spectrometer over different plant canopies. Results show that the relative mean absolute errors between the normalized nadir SIF and the observed SIF at nadir decrease by 3–6% (far-red) and 6–8% (red) for the first approach, and by 7–13% and 6–11% for the second approach, compared to the original data, respectively. The effectiveness and simplicity of our proposed approaches provide great potential to generate long-term and consistent SIF data records with minimized directional effects.
Articolo in rivista - Articolo scientifico
Angular normalization; Directional effects; Kernel-driven model; Near-infrared reflectance of vegetation; Red reflectance of vegetation; Solar-induced chlorophyll fluorescence;
English
24-dic-2020
2021
255
15 March 2021
112171
none
Hao, D., Zeng, Y., Qiu, H., Biriukova, K., Celesti, M., Migliavacca, M., et al. (2021). Practical approaches for normalizing directional solar-induced fluorescence to a standard viewing geometry. REMOTE SENSING OF ENVIRONMENT, 255(15 March 2021) [10.1016/j.rse.2020.112171].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/324424
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