scholarly journals UPSCALING OF SOLAR INDUCED CHLOROPHYLL FLUORESCENCE FROM LEAF TO CANOPY USING THE DART MODEL AND A REALISTIC 3D FOREST SCENE

2017 ◽  
Vol XLII-3/W3 ◽  
pp. 107-111 ◽  
Author(s):  
W. Liu ◽  
J. Atherton ◽  
M. Mõttus ◽  
A. MacArthur ◽  
H. Teemu ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Forest Canopy ◽  
Multiple Scales ◽  
Canopy Structure ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Fluorescence Signal ◽  
Forest Canopies ◽  
Vertical Heterogeneity ◽  
Leaf Level

Solar induced chlorophyll a fluorescence (SIF) has been shown to be an excellent proxy of photosynthesis at multiple scales. However, the mechanical linkages between fluorescence and photosynthesis at the leaf level cannot be directly applied at canopy or field scales, as the larger scale SIF emission depends on canopy structure. This is especially true for the forest canopies characterized by high horizontal and vertical heterogeneity. While most of the current studies on SIF radiative transfer in plant canopies are based on the assumption of a homogeneous canopy, recently codes have been developed capable of simulation of fluorescence signal in explicit 3-D forest canopies. Here we present a canopy SIF upscaling method consisting of the integration of the 3-D radiative transfer model DART and a 3-D object model BLENDER. Our aim was to better understand the effect of boreal forest canopy structure on SIF for a spatially explicit forest canopy.

scholarly journals Radiative Transfer Modeling of a Coniferous Canopy Characterized by Airborne Remote Sensing

2008 ◽  
Vol 9 (2) ◽  
pp. 228-241 ◽  
Author(s):  
Richard Essery ◽  
Peter Bunting ◽  
Aled Rowlands ◽  
Nick Rutter ◽  
Janet Hardy ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Laser Scanning ◽  
Large Scale ◽  
Forest Canopy ◽  
Canopy Structure ◽  
Spatial Variations ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Temporal Averaging ◽  
Radiative Transfer Modeling

Abstract Solar radiation beneath a forest canopy can have large spatial variations, but this is frequently neglected in radiative transfer models for large-scale applications. To explicitly model spatial variations in subcanopy radiation, maps of canopy structure are required. Aerial photography and airborne laser scanning are used to map tree locations, heights, and crown diameters for a lodgepole pine forest in Colorado as inputs to a spatially explicit radiative transfer model. Statistics of subcanopy radiation simulated by the model are compared with measurements from radiometer arrays, and scaling of spatial statistics with temporal averaging and array size is discussed. Efficient parameterizations for spatial averages and standard deviations of subcanopy radiation are developed using parameters that can be obtained from the model or hemispherical photography.

scholarly journals FLiES-SIF ver. 1.0: Three-dimensional radiative transfer model for estimating solar induced fluorescence

2020 ◽  
Author(s):  
Yuma Sakai ◽  
Hideki Kobayashi ◽  
Tomomichi Kato
Keyword(s):  
Sensitivity Analysis ◽  
Chlorophyll Fluorescence ◽  
Radiative Transfer ◽  
Three Dimensional ◽  
Radiative Transfer Model ◽  
Model Description ◽  
Transfer Model ◽  
Plant Canopy ◽  
Parallel Layer ◽  
Leaf Level

Abstract. Global terrestrial ecosystems control the atmospheric CO2 concentration through gross primary production (GPP) and ecosystem respiration processes. Chlorophyll fluorescence is one of the energy release pathways of excess incident lights in the photosynthetic process. Over the last ten years, extensive studies have been revealed that canopy scale sun-induced chlorophyll fluorescence (SIF), which potentially provides a direct pathway to link leaf level photosynthesis to global GPP, can be observed from satellites. SIF is used to infer photosynthetic capacity of plant canopy, however, it is not clear how the leaf-level SIF emission contributes to the top of canopy directional SIF. Plant canopy radiative transfer models are the useful tools to understand the causality of directional canopy SIF. One dimensional (1-D) plane parallel layer models (e.g. the Soil Canopy Observation, Photochemistry and Energy fluxes (SCOPE) model) have been widely used and are useful to understand the general mechanisms behind the temporal and seasonal variations in SIF. However, due to the lack of complexity of the actual canopy structures, three dimensional models (3-D) have a potential to delineate the realistic directional canopy SIFs. Forest Light Environmental Simulator for SIF (FLiES-SIF) version 1.0 is the 3-D Monte Carlo plant canopy radiative transfer model to understand the biological and physical mechanisms behind the SIF emission from complex forest canopies. In this model description paper, we focused on the model formulation and simulation schemes, and showed some sensitivity analysis against several major variables such as view angle and leaf area index (LAI). The simulation results show that SIF increases with LAI then saturated at LAI > 2–4 depending on the spectral wavelength. The sensitivity analysis also shows that simulated SIF radiation may decrease with LAI at higher LAI domain (LAI > 5). These phenomena are seen in certain sun and view angle conditions. This type of non-linear and non-monotonic SIF behavior to LAI is also related to spatial forest structure patterns. FLiES-SIF version 1.0 can be used to quantify the canopy SIF in various view angles including the contribution of multiple scattering which is the important component in the near infrared domain. The potential use of the model is to standardize the satellite SIF by correcting the bi-directional effect. This step will contribute to the improvement of the GPP estimation accuracy through SIF.

A First-Order Radiative Transfer Model for Microwave Radiometry of Forest Canopies at L-Band

2011 ◽  
Vol 49 (9) ◽  
pp. 3167-3179 ◽  
Author(s):  
Mehmet Kurum ◽  
Roger H. Lang ◽  
Peggy E. O'Neill ◽  
Alicia T. Joseph ◽  
Thomas J. Jackson ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Microwave Radiometry ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Forest Canopies ◽  
First Order ◽  
L Band

scholarly journals Radiative Transfer Modeling of Phytoplankton Fluorescence Quenching Processes

2018 ◽  
Vol 10 (8) ◽  
pp. 1309 ◽  
Author(s):  
Peng-Wang Zhai ◽  
Emmanuel Boss ◽  
Bryan Franz ◽  
P. Werdell ◽  
Yongxiang Hu
Keyword(s):  
Quantum Yield ◽  
Radiative Transfer ◽  
Sensitivity Study ◽  
Radiative Transfer Model ◽  
Photochemical Quenching ◽  
Transfer Model ◽  
Fluorescence Signal ◽  
New Space ◽  
Non Photochemical Quenching ◽  
Radiative Transfer Modeling

We report the first radiative transfer model that is able to simulate phytoplankton fluorescence with both photochemical and non-photochemical quenching included. The fluorescence source term in the inelastic radiative transfer equation is proportional to both the quantum yield and scalar irradiance at excitation wavelengths. The photochemical and nonphotochemical quenching processes change the quantum yield based on the photosynthetic active radiation. A sensitivity study was performed to demonstrate the dependence of the fluorescence signal on chlorophyll a concentration, aerosol optical depths and solar zenith angles. This work enables us to better model the phytoplankton fluorescence, which can be used in the design of new space-based sensors that can provide sufficient sensitivity to detect the phytoplankton fluorescence signal. It could also lead to more accurate remote sensing algorithms for the study of phytoplankton physiology.

scholarly journals FLiES-SIF version 1.0: three-dimensional radiative transfer model for estimating solar induced fluorescence

2020 ◽  
Vol 13 (9) ◽  
pp. 4041-4066
Author(s):  
Yuma Sakai ◽  
Hideki Kobayashi ◽  
Tomomichi Kato
Keyword(s):  
Sensitivity Analysis ◽  
Chlorophyll Fluorescence ◽  
Radiative Transfer ◽  
Three Dimensional ◽  
Radiative Transfer Model ◽  
Model Description ◽  
Transfer Model ◽  
Plant Canopy ◽  
Parallel Layer ◽  
Leaf Level

Abstract. Global terrestrial ecosystems control the atmospheric CO2 concentration through gross primary production (GPP) and ecosystem respiration processes. Chlorophyll fluorescence is one of the energy release pathways of excess incident light in the photosynthetic process. Over the last 10 years, extensive studies have revealed that canopy-scale Sun-induced chlorophyll fluorescence (SIF), which potentially provides a direct pathway to link leaf-level photosynthesis to global GPP, can be observed from satellites. SIF is used to infer photosynthetic capacity of plant canopy; however, it is not clear how the leaf-level SIF emission contributes to the top-of-canopy directional SIF. Plant canopy radiative transfer models are useful tools to understand the mechanism of anisotropic light interactions such as scattering and absorption in plant canopies. One-dimensional (1-D) plane-parallel layer models (e.g., the Soil Canopy Observation, Photochemistry and Energy fluxes (SCOPE) model) have been widely used and are useful to understand the general mechanisms behind the temporal and seasonal variations in SIF. However, a 1-D model does not explain the complexity of the actual canopy structures. Three-dimensional models (3-D) have a potential to delineate the realistic directional canopy SIFs. Forest Light Environmental Simulator for SIF (FLiES-SIF) version 1.0 is a 3-D Monte Carlo plant canopy radiative transfer model to understand the biological and physical mechanisms behind the SIF emission from complex forest canopies. The FLiES-SIF model is coupled with leaf-level fluorescence and a physiology module so that users are able to simulate how the changes in environmental and leaf traits as well as canopy structure affect the observed SIF at the top of the canopy. The FLiES-SIF model was designed as three-dimensional model, yet the entire modules are computationally efficient: FLiES-SIF can be easily run by moderate-level personal computers with lower memory demands and public software. In this model description paper, we focused on the model formulation and simulation schemes, and showed some sensitivity analysis against several major variables such as view angle and leaf area index (LAI). The simulation results show that SIF increases with LAI then saturated at LAI>2–4 depending on the spectral wavelength. The sensitivity analysis also shows that simulated SIF radiation may decrease with LAI at a higher LAI domain (LAI>5). These phenomena are seen in certain Sun and view angle conditions. This type of nonlinear and nonmonotonic SIF behavior towards LAI is also related to spatial forest structure patterns. FLiES-SIF version 1.0 can be used to quantify the canopy SIF in various view angles including the contribution of multiple scattering which is the important component in the near-infrared domain. The potential use of the model is to standardize the satellite SIF by correcting the bidirectional effect. This step will contribute to the improvement of the GPP estimation accuracy through SIF.

scholarly journals Application of a Three-Dimensional Radiative Transfer Model to Retrieve the Species Composition of a Mixed Forest Stand from Canopy Reflected Radiation

2018 ◽  
Vol 10 (10) ◽  
pp. 1661 ◽  
Author(s):  
Natalia Levashova ◽  
Dmitry Lukyanenko ◽  
Yulia Mukhartova ◽  
Alexander Olchev
Keyword(s):  
Solar Radiation ◽  
Radiative Transfer ◽  
Tree Species ◽  
Forest Canopy ◽  
Mixed Forest ◽  
Three Dimensional ◽  
Forest Stand ◽  
Deciduous Tree ◽  
Radiative Transfer Model ◽  
Transfer Model

The paper introduces a three-dimensional model to derive the spatial patterns of photosynthetically active radiation (PAR) reflected and absorbed by a non-uniform forest canopy with a multi-species structure, as well as a model algorithm application to retrieve forest canopy composition from reflected PAR measured along some trajectory above the forest stand. This radiative transfer model is based on steady-state transport equations, initially suggested by Ross, and considers the radiative transfer as a function of the structure of individual trees and forest canopy, optical properties of photosynthesizing and non-photosynthesizing parts of the different tree species, soil reflection, and the ratio of incoming direct and diffuse solar radiation. Numerical experiments showed that reflected solar radiation of a typical mixed forest stand consisting of coniferous and deciduous tree species was strongly governed by canopy structure, soil properties and sun elevation. The suggested algorithm based on the developed model allows for retrieving the proportion of different tree species in a mixed forest stand from measured canopy reflection coefficients. The method accuracy strictly depends on the number of points for canopy reflection measurements.

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