Sun-Induced Chlorophyll Fluorescence I: Instrumental Considerations for Proximal Spectroradiometers

Pacheco‐Labrador, Javier; Hueni, Andreas; Mihai, Laura; Sakowska, Karolina; Julitta, Tommaso; Kuusk, Joel; Sporea, Dan; Alonso, Luis; Burkart, Andreas; Cendrero-Mateo, Maria Pilar; Aasen, Helge; Goulas, Y.; Arthur, Alasdair Mac

doi:10.3390/rs11080960

Cited by 33 publications

(34 citation statements)

References 59 publications

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“…Therefore, we used the area of the peak as shown in Equation (11) instead of the height for the quantitative measure of the in-filling of the O 2 -A Fraunhofer line F area in our data. To avoid speculations, we call the variable which we measured strictly as the in-filling of the O 2 -A Fraunhofer line and not chlorophyll fluorescence, although the measured signal must also contain significant contribution of SIF [49,50].…”

Section: The In-filling Of the O 2 -A Fraunhofer Linementioning

confidence: 99%

Reflectance Properties of Hemiboreal Mixed Forest Canopies with Focus on Red Edge and Near Infrared Spectral Regions

et al. 2019

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This study present the results of airborne top-of-canopy measurements of reflectance spectra in the spectral domain of 350-1050 nm over the hemiboreal mixed forest. We investigated spectral transformations that were originally designed for utilization at very different spectral resolutions. We found that the estimates of red edge inflection point by two methods-the linear four-point interpolation approach (S2REP) and searching the maximum of the first derivative spectrum (D max ) according to the mathematical definition of red edge inflection point-were well related to each other but S2REP produced a continuously shifting location of red edge inflection point while D max resulted in a discrete variable with peak jumps between fixed locations around 717 nm and 727 nm for forest canopy (the third maximum at 700 nm appeared only in clearcut areas). We found that, with medium high spectral resolution (bandwidth 10 nm, spectral step 3.3 nm), the in-filling of the O 2 -A Fraunhofer line (F area ) was very strongly related to single band reflectance factor in NIR spectral region (ρ = 0.91, p < 0.001) and not related to Photochemical Reflectance Index (PRI). Stemwood volume, basal area and tree height of dominant layer were negatively correlated with reflectance factors at both visible and NIR spectral region due to the increase in roughness of canopy surface and the amount of shade. Forest age was best related to single band reflectance at NIR region (ρ = −0.48, p < 0.001) and the best predictor for allometric LAI was the single band reflectance at red spectral region (ρ = −0.52, p < 0.001) outperforming all studied vegetation indices. It suggests that Sentinel-2 MSI bands with higher spatial resolution (10 m pixel size) could be more beneficial than increased spectral resolution for monitoring forest LAI and age. The new index R 751 /R 736 originally developed for leaf chlorophyll content estimation, also performed well at the canopy level and was mainly influenced by the location of red edge inflection point (ρ = 0.99, p < 0.001) providing similar info in a simpler mathematical form and using a narrow spectral region very close to the O 2 -A Fraunhofer line.

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Section: The In-filling Of the O 2 -A Fraunhofer Linementioning

confidence: 99%

Reflectance Properties of Hemiboreal Mixed Forest Canopies with Focus on Red Edge and Near Infrared Spectral Regions

et al. 2019

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“…For this reason, many researchers have worked within the framework of a European cooperation in science and technology (COST) action, "Innovative optical tools for proximal sensing of ecophysiological processes" (OPTIMISE, ES1309; https://optimise.dcs.aber.ac.uk/) over the last four years to address these challenges. The OPTIMISE community has compiled three papers: One on instrument characterization [30], one on measurement setups and protocols [31], and this paper on retrieval methods to make gathered information available. This compilation of papers aims to summarize the state-of-the-art for high quality SIF measurements and bring up-to-date the review papers of Meroni et al [9] and Damm et al [32].…”

Section: Introductionmentioning

confidence: 99%

Sun-Induced Chlorophyll Fluorescence III: Benchmarking Retrieval Methods and Sensor Characteristics for Proximal Sensing

et al. 2019

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The interest of the scientific community on the remote observation of sun‐induced chlorophyll fluorescence (SIF) has increased in the recent years. In this context, hyperspectral ground measurements play a crucial role in the calibration and validation of future satellite missions. For this reason, the European cooperation in science and technology (COST) Action ES1309 OPTIMISE has compiled three papers on instrument characterization, measurement setups and protocols, and retrieval methods (current paper). This study is divided in two sections; first, we evaluated the uncertainties in SIF retrieval methods (e.g., Fraunhofer line depth (FLD) approaches and spectral fitting method (SFM)) for a combination of off-the-shelf commercial spectrometers. Secondly, we evaluated how an erroneous implementation of the retrieval methods increases the uncertainty in the estimated SIF values. Results show that the SFM approach applied to high-resolution spectra provided the most reliable SIF retrieval with a relative error (RE) ≤6% and <5% for F687 and F760, respectively. Furthermore, although the SFM was the least affected by an inaccurate definition of the absorption spectral window (RE = 5%) and/or interpolation strategy (RE = 15%–30%), we observed a sensitivity of the SIF retrieval for the simulated training data underlying the SFM model implementation.

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“…Recently, Remote Sensing (ISSN 2072-4292) had published three manuscripts in its Special Issue "OPTIMISE: Innovative Optical Tools for Proximal Sensing of Ecophysiological Processes" addressing the review of Proximal Spectroradiometers for SIF estimation by Pacheco-Labrador et al [97], Aasen et al [98], and Cendrero-Mateo et al [39]. First, Pacheco-Labrador et al [97] discussed the effects of instrumental noise and biases on SIF retrieval. This review also highlights the associated uncertainties that are required for the calibration and characterization of the state-of-the-art SIF-oriented spectroradiometers.…”

Section: Development Of the New Ground-based Passive Systems For Top-mentioning

confidence: 99%

Review of Top-of-Canopy Sun-Induced Fluorescence (SIF) Studies from Ground, UAV, Airborne to Spaceborne Observations

Bandopadhyay

Rastogi

Juszczak

2020

Sensors

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Remote sensing (RS) of sun-induced fluorescence (SIF) has emerged as a promising indicator of photosynthetic activity and related stress from the leaf to the ecosystem level. The implementation of modern RS technology on SIF is highly motivated by the direct link of SIF to the core of photosynthetic machinery. In the last few decades, a lot of studies have been conducted on SIF measurement techniques, retrieval algorithms, modeling, application, validation, and radiative transfer processes, incorporating different RS observations (i.e., ground, unmanned aerial vehicle (UAV), airborne, and spaceborne). These studies have made a significant contribution to the enrichment of SIF science over time. However, to realize the potential of SIF and to explore its full spectrum using different RS observations, a complete document of existing SIF studies is needed. Considering this gap, we have performed a detailed review of current SIF studies from the ground, UAV, airborne, and spaceborne observations. In this review, we have discussed the in-depth interpretation of each SIF study using four RS platforms. The limitations and challenges of SIF studies have also been discussed to motivate future research and subsequently overcome them. This detailed review of SIF studies will help, support, and inspire the researchers and application-based users to consider SIF science with confidence.

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Sun-Induced Chlorophyll Fluorescence I: Instrumental Considerations for Proximal Spectroradiometers

Cited by 33 publications

References 59 publications

Reflectance Properties of Hemiboreal Mixed Forest Canopies with Focus on Red Edge and Near Infrared Spectral Regions

Reflectance Properties of Hemiboreal Mixed Forest Canopies with Focus on Red Edge and Near Infrared Spectral Regions

Sun-Induced Chlorophyll Fluorescence III: Benchmarking Retrieval Methods and Sensor Characteristics for Proximal Sensing

Review of Top-of-Canopy Sun-Induced Fluorescence (SIF) Studies from Ground, UAV, Airborne to Spaceborne Observations

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