Integrated modeling of canopy photosynthesis, fluorescence, and the transfer of energy, mass, and momentum in the soil–plant–atmosphere continuum (STEMMUS–SCOPE v1.0.0)

Abstract

Abstract. Root water uptake by plants is a vital process that influences terrestrial energy, water, and carbon exchanges. At the soil, vegetation, and atmosphere interfaces, root water uptake and solar radiation predominantly regulate the dynamics and health of vegetation growth, which can be remotely monitored by satellites, using the soil–plant relationship proxy – solar-induced chlorophyll fluorescence. However, most current canopy photosynthesis and fluorescence models do not account for root water uptake, which compromises their applications under water-stressed conditions. To address this limitation, this study integrated photosynthesis, fluorescence emission, and transfer of energy, mass, and momentum in the soil–plant–atmosphere continuum system, via a simplified 1D root growth model and a resistance scheme linking soil, roots, leaves, and the atmosphere. The coupled model was evaluated with field measurements of maize and grass canopies. The results indicated that the simulation of land surface fluxes was significantly improved by the coupled model, especially when the canopy experienced moderate water stress. This finding highlights the importance of enhanced soil heat and moisture transfer, as well as dynamic root growth, on simulating ecosystem functioning.

Modelling of Multi-Frequency Microwave Backscatter and Emission of Land Surface by a Community Land Active Passive Microwave Radiative Transfer Modelling Platform (CLAP)

“…It is noted that the essential CLAP inputs such as moisture content and temperature of soil and vegetation as well as vegetation geometry (e.g., size, shape, 705 orientation and distributions of elements) are not always available in situ. One of the innovative approaches to circumvent this limitation is to include the integrated process model STEMMUS-SCOPE (Wang et al, 2021b) in the CLAP, in which the SCOPE (Van Der Tol et al, 2009) radiative and photochemical processes provides vegetation information and STEMMUS model (Zeng et al, 2011a;Yu et al, 2018;Yu, 2022) provides information of profile soil moisture and temperature. The 710 corresponding investigations carried out with this new integrated framework are expected to provide insights for resolving the challenge of remote sensing of vegetation: to be able to describe and separate the contributions of the different components in the observed total signature of the vegetated lands, to further root satellite observations into the actual surface conditions for ecological and hydrological applications.…”

Down to the root of vegetated soil: challenges and state-of-the-art

“…The soil water potential at depth z ψ s (z, t) and the leaf water potential at the surface of the root ψ l (t) is what drives the water uptake. The proportionality α is essentially derived from the root architecture, e.g., by taking into account the axial conductivity and root geometry (see its various formulations in [34,65,66]). Substituting the following constitutive laws into Eq.…”

“…In order to describe the response of root growth to the soil environment (e.g., pore pressure, nutrient concentration, pore size distribution), root architecture models, are coupled with soil water flow models [66]. At the root scale, the root water uptake is driven by the time-evolving distribution of the water potential gradients between soil and root.…”

“…Promising constitutive models [23,24] have been proposed for rooted soil with predefined root system architecture. To develop mechanical models that can be integrated into a so-called soil-plantatmosphere framework [94], root system growth and its influence on the water retention capacity should be incorporated. In a similar fashion as the discrete and the continuum model are developed for the root-zone bio-hydrology, constitutive laws for rooted soil should be developed at the particle/root scale and the macroscopic scale, in order to facilitate their coupling.…”

STEMMUS-UEB v1.0.0: integrated modeling of snowpack and soil water and energy transfer with three complexity levels of soil physical processes

“…It is achieved by simultaneously solving the balance equations of soil mass, energy, and dry air in a fully coupled way. The mediation effect of vegetation on such interactions was recently incorporated via the root water uptake sub-module (Yu et al, 2016) and by coupling with the detailed soil and vegetation biogeochemical process (Wang et al, 2021;Yu et al, 2020a). It facilitates our understanding of the hydrothermal dynamics of respective components in the frozen soil medium (i.e., soil liquid water, water vapor, dry air, and ice) by implementing the freezethaw process (hereafter STEMMUS-FT, for applications in cold regions, Yu et al, 2018aYu et al, , 2020c.…”