Estimating forest canopy parameters from satellite waveform LiDAR by inversion of the FLIGHT three-dimensional radiative 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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Evaluation of shortwave radiation fluxes in the multi-layer SPARTACUS-Urban scheme using DART

10.5194/egusphere-egu21-16076 ◽

2021 ◽

Author(s):

Megan Stretton ◽

William Morrison ◽

Robin Hogan ◽

Sue Grimmond

Keyword(s):

Radiative Transfer ◽

Urban Form ◽

Climate Models ◽

Weather Prediction ◽

Computational Cost ◽

Three Dimensional ◽

Shortwave Radiation ◽

Radiative Transfer Model ◽

Transfer Model ◽

Urban Structure

<p>The heterogenous structure of cities impacts radiative exchanges (e.g. albedo and heat storage). Numerical weather prediction (NWP) models often characterise the urban structure with an infinite street canyon &#8211; but this does not capture the three-dimensional urban form. SPARTACUS-Urban (SU) - a fast, multi-layer radiative transfer model designed for NWP - is evaluated using the explicit Discrete Anisotropic Radiative Transfer (DART) model for shortwave fluxes across several model domains &#8211; from a regular array of cubes to real cities .</p><p>SU agrees with DART (errors < 5.5% for all variables) when the SU assumptions of building distribution are fulfilled (e.g. randomly distribution). For real-world areas with pitched roofs, SU underestimates the albedo (< 10%) and shortwave transmission to the surface (< 15%), and overestimates wall-plus-roof absorption (9-27%), with errors increasing with solar zenith angle. SU should be beneficial to weather and climate models, as it allows more realistic urban form (cf. most schemes) without large increases in computational cost.</p>

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A simplified description of the three-dimensional structure of agroforestry trees for use with a radiative transfer model

Agroforestry for Sustainable Land-Use Fundamental Research and Modelling with Emphasis on Temperate and Mediterranean Applications - Forestry Sciences ◽

10.1007/978-94-017-0679-7_8 ◽

1999 ◽

pp. 121-134

Author(s):

S. Meloni

Keyword(s):

Radiative Transfer ◽

Three Dimensional ◽

Dimensional Structure ◽

Radiative Transfer Model ◽

Transfer Model ◽

Three Dimensional Structure

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A pseudo three-dimensional resonance line radiative transfer model with overlapping lines

Journal of Geophysical Research Atmospheres ◽

10.1029/1999je001231 ◽

2000 ◽

Vol 105 (E10) ◽

pp. 24613-24620 ◽

Cited By ~ 4

Author(s):

Erik Griffioen

Keyword(s):

Radiative Transfer ◽

Resonance Line ◽

Three Dimensional ◽

Radiative Transfer Model ◽

Transfer Model ◽

Dimensional Resonance

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

10.5194/gmd-2020-19 ◽

2020 ◽

Cited By ~ 1

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.

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Seeking edge-on galaxies with substantial extraplanar dust using a radiative transfer model: determination of the model parameter uncertainties for EON_10.477_41.954 (FGC 79)

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2442 ◽

2019 ◽

Vol 489 (4) ◽

pp. 4690-4704 ◽

Cited By ~ 1

Author(s):

Jong-Ho Shinn

Keyword(s):

Radiative Transfer ◽

Confidence Intervals ◽

Three Dimensional ◽

Radiative Transfer Model ◽

Model Parameters ◽

Transfer Model ◽

Target Classification ◽

Parameter Uncertainties ◽

Model Parameter ◽

Galaxy Model

ABSTRACT We have revisited the target EON_10.477_41.954 in order to determine more accurately the uncertainties in the model parameters that are important for target classification (i.e. galaxies with or without substantial extraplanar dust). We performed a Markov chain Monte Carlo (MCMC) analysis for the 15 parameters of the three-dimensional radiative-transfer galaxy model we used previously for target classification. To investigate the convergence of the MCMC sampling – which is usually neglected in the literature but should not be – we monitored the integrated autocorrelation time (τint), and we achieved effective sample sizes >5650 for all the model parameters. The confidence intervals are unstable at the beginning of the iterations where the values of τint are increasing, but they become stable in later iterations where those values are almost constant. The final confidence intervals are ∼5–100 times larger than the nominal uncertainties used in our previous study (the standard deviation of three best-fitting results). Thus, those nominal uncertainties are not good proxies for the model-parameter uncertainties. Although the position of EON_10.477_41.954 in the target-classification plot (the scale height to diameter ratio of dust versus that of light source) decreases by about 20–30 per cent when compared to our previous study, its membership in the ‘high-group’ – i.e. among galaxies with substantial extraplanar dust – nevertheless remains unchanged.

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