Abstract

Abstract. The Soil Canopy Observation of Photosynthesis and Energy fluxes (SCOPE) model aims at linking satellite observations in the visible, infrared, and thermal domains with land surface processes in a physically based manner, and quantifying the microclimate in vegetation canopies. It simulates radiative transfer in the soil, leaves, and vegetation canopies, as well as photosynthesis and non-radiative heat dissipation through convection and mechanical turbulence. Since the first publication 12 years ago, SCOPE has been applied in remote sensing studies of solar-induced chlorophyll fluorescence (SIF), energy balance fluxes, gross primary production (GPP), and directional thermal signals. Here, we present a thoroughly revised version, SCOPE 2.0, which features a number of new elements: (1) it enables the definition of layers consisting of leaves with different properties, thus enabling the simulation of vegetation with an understorey or with a vertical gradient in leaf chlorophyll concentration; (2) it enables the simulation of soil reflectance; (3) it includes the simulation of leaf and canopy reflectance changes induced by the xanthophyll cycle; and (4) the computation speed has been reduced by 90 % compared to earlier versions due to a fundamental optimization of the model. These new features improve the capability of the model to represent complex canopies and to explore the response of remote sensing signals to vegetation physiology. The improvements in computational efficiency make it possible to use SCOPE 2.0 routinely for the simulation of satellite data and land surface fluxes. It also strengthens the operability for the numerical retrieval of land surface products from satellite or airborne data.

Highlights

  • Vegetation, as a dynamic component of the Earth system, affects the climate via its influence on the exchange of energy and matter between the land surface and the atmosphere

  • They include one Radiative transfer models (RTMs) for incident radiation from the Sun and the sky (RTMo), two for thermal radiation emitted by the soil and vegetation (RTMt_sb and RTMt_planck), one for chlorophyll fluorescence (RTMf, van der Tol et al, 2009; Van der Tol et al, 2019), and one for the dynamic modulations of leaf reflectance and transmittance due to pigment changes in the xanthophyll cycle (RTMz, only available in SCOPE v1.70 or later, Vilfan et al, 2018)

  • RTM for fluxes induced by the xanthophyll cycle leaf-absorbed radiation, canopy structure, leaf reflectance, transmittance, soil reflectance dynamic modulations of canopy reflectance biochemical biochemical model for photosystem energy partitioning leaf-absorbed radiation, leaf tempera- photosynthesis rate, fluorescence emisture, photosynthetic parameters sion efficiency and heat dissipation ebal energy balance leaf-absorbed radiation, leaf tempera- sensible and latent heat fluxes module ture

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Summary

Introduction

Vegetation, as a dynamic component of the Earth system, affects the climate via its influence on the exchange of energy and matter between the land surface and the atmosphere. Combined radiative transfer and plant physiological modelling is a promising way to investigate the exchange of energy, water, and carbon among soil, vegetation, and atmosphere, and to develop remote sensing techniques for monitoring of vegetation functioning. One needs to model non-radiative processes of energy dissipation via photosynthesis, phase transitions of water, heat storage, and turbulent heat exchange between the surface and the atmosphere This enables investigations beyond the monitoring of vegetation biophysical and biochemical properties, towards monitoring of fluxes. The Soil Canopy Observation of Photosynthesis and Energy fluxes (SCOPE) model simulates the radiative transfer of incident light and thermal and fluorescence radiation emitted by soil and plants, component temperatures, photosynthesis, and turbulent heat exchange (van der Tol et al, 2009). We present a description of basic functionality of the model followed by several recent developments

Starting points
Model domain and representation
Structure of the model
Energy balance module
Leaf biochemical model
Interactions among the submodels
Model inputs and outputs
Input irradiance for the atmosphere boundary condition
Model outputs
Implementation of the BSM soil reflectance model
Inclusion of dynamic reflectance induced by the xanthophyll cycle
Adaption of the RTMs for multi-layer canopies
An alternative way to estimate the ground heat flux
Improvements in energy balance closure
Angular aggregation of sunlit leaves
Improvements in the computational efficiency
Additional outputs
Findings
Conclusions
Full Text
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