Evaluation of remote sensing of vegetation fluorescence by the analysis of diurnal cycles

Abstract

Chlorophyll fluorescence (ChF) emission is a direct indicator of the photosynthetic activity of vegetation, which is a key parameter of the carbon cycle. This paper analyses chlorophyll fluorescence evolution at leaf level during a complete diurnal cycle in simulated and natural conditions, for two species under different stress conditions. Absolute spectral radiance of the ChF emission is obtained allowing a quantitative derivation of the fluorescence yield of the ChF, which correlates well with established fluorescence instruments. The studied cases show that the ChF emission is mainly driven by the photosynthetic active radiation during the whole cycle, but the fluorescence yield is severely reduced during the central hours of the day when the plant is under stress due to light and heat. Results show that the Fraunhofer Line Discriminator method is an accurate way of retrieving quantitative values of ChF from remote sensing sensors at 760 nm and suggest that the mid-morning period is the best time of the day to maximize signal levels while identifying vegetation stress state.

New Spectral Fitting Method for Full-Spectrum Solar-Induced Chlorophyll Fluorescence Retrieval Based on Principal Components Analysis

“…The results show that the double-peak characteristic of the SIF spectrum has been successfully reconstructed; the diurnal variation trend in the SIF is also reasonable and consistent with the results from literature (e.g. [40][41][42]). …”

Diurnal Cycle Relationships between Passive Fluorescence, PRI and NPQ of Vegetation in a Controlled Stress Experiment

“…The fiber optic of the ASD spectroradiometer was aligned to point to the This experiment was conducted in 2006 and partly presented in an earlier work that investigated the comparability of the active and passive Chl F measurements and formulated the best satellite overpass time for the remote sensing of Chl F [16][17][18]. Here, we present new results on the diurnal interaction between the different energy dissipation mechanisms that can be measured through active and passive techniques.…”

Tracking photosynthetic injury of Paraquat-treated crop using chlorophyll fluorescence from hyperspectral data

“…Although the observed vegetation reflectance inevitably includes contributions from both reflected and fluoresced radiation, many researchers have proved that it is possible to separate SIF radiation from observed apparent vegetation reflectance. For example, the SIF signals at 656 nm, 687 nm, and 760 nm were successfully separated from the observed apparent vegetation reflectance based on the Fraunhofer-line principle [Mcfarlane et al, 1980;Carter et al, 1996;Liu et al, 2005;Amoros-Lopez et al, 2008]. Furthermore, Guanter et al [2007] proved for the first time that spaceborne estimation of chlorophyll fluorescence is feasible by coupling an atmospheric correction scheme during the SIF retrieval.…”

“…The SIF signal is less than 1% of the incident energy, but in principle it can be separated from the reflectance signal. The effect of chlorophyll fluorescence emissions on the apparent vegetation reflectance spectrum has recently been investigated [Zarco-Tejada et al, 2001;Liu et al, 2005;Amoros-Lopez et al, 2008]. Although the observed vegetation reflectance inevitably includes contributions from both reflected and fluoresced radiation, many researchers have proved that it is possible to separate SIF radiation from observed apparent vegetation reflectance.…”