Structural Constraints in Current Stomatal Conductance Models Preclude Accurate Prediction of Evapotranspiration

Abstract Evapotranspiration (ET) plays a critical role in water and energy budgets at regional to global scales. ET is composed of direct evaporation (E) and plant transpiration (T) where the latter is regulated via stomatal conductance (gsc), which depends on a multitude of plant physiological proc...

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Main Authors: Pushpendra Raghav, Mukesh Kumar, Yanlan Liu
Format: Article
Language:English
Published: Wiley 2024-08-01
Series:Water Resources Research
Subjects:
Online Access:https://doi.org/10.1029/2024WR037652
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author Pushpendra Raghav
Mukesh Kumar
Yanlan Liu
author_facet Pushpendra Raghav
Mukesh Kumar
Yanlan Liu
author_sort Pushpendra Raghav
collection DOAJ
description Abstract Evapotranspiration (ET) plays a critical role in water and energy budgets at regional to global scales. ET is composed of direct evaporation (E) and plant transpiration (T) where the latter is regulated via stomatal conductance (gsc), which depends on a multitude of plant physiological processes and hydrometeorological forcings. In recent years, significant advances have been made toward estimating gsc using a variety of models, ranging from relatively simple empirical models to more complex and data‐intensive plant hydraulic models. Using machine learning (ML) and eddy covariance flux tower data of 642 site years across 84 sites distributed across 10 land covers globally, here we show that structural constraints inherent in current empirical and plant hydraulic models of gsc limit their effectiveness for predicting ET. These constraints also prevent the models from fully utilizing the available hydrometeorological data at eddy covariance sites. Even if these gsc models are calibrated locally, structural simplifications inherent in them limit their capability to accurately capture gsc dynamics. In contrast, a ML approach, wherein the model structure is learned from the data, outperforms traditional models, thus highlighting that there still is significant room for improvement in the structure of traditional models for predicting ET. These results underscore the need to prioritize improvements in gsc models for more accurate ET estimation. This, in turn, will help reduce uncertainties in the assessments of plants' role in regulating the Earth's climate.
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spelling doaj-art-bd966addc7c44005b3992c7db6c3e55e2025-08-20T02:58:21ZengWileyWater Resources Research0043-13971944-79732024-08-01608n/an/a10.1029/2024WR037652Structural Constraints in Current Stomatal Conductance Models Preclude Accurate Prediction of EvapotranspirationPushpendra Raghav0Mukesh Kumar1Yanlan Liu2Department of Civil, Construction, and Environmental Engineering University of Alabama Tuscaloosa AL USADepartment of Civil, Construction, and Environmental Engineering University of Alabama Tuscaloosa AL USASchool of Earth Sciences The Ohio State University Columbus OH USAAbstract Evapotranspiration (ET) plays a critical role in water and energy budgets at regional to global scales. ET is composed of direct evaporation (E) and plant transpiration (T) where the latter is regulated via stomatal conductance (gsc), which depends on a multitude of plant physiological processes and hydrometeorological forcings. In recent years, significant advances have been made toward estimating gsc using a variety of models, ranging from relatively simple empirical models to more complex and data‐intensive plant hydraulic models. Using machine learning (ML) and eddy covariance flux tower data of 642 site years across 84 sites distributed across 10 land covers globally, here we show that structural constraints inherent in current empirical and plant hydraulic models of gsc limit their effectiveness for predicting ET. These constraints also prevent the models from fully utilizing the available hydrometeorological data at eddy covariance sites. Even if these gsc models are calibrated locally, structural simplifications inherent in them limit their capability to accurately capture gsc dynamics. In contrast, a ML approach, wherein the model structure is learned from the data, outperforms traditional models, thus highlighting that there still is significant room for improvement in the structure of traditional models for predicting ET. These results underscore the need to prioritize improvements in gsc models for more accurate ET estimation. This, in turn, will help reduce uncertainties in the assessments of plants' role in regulating the Earth's climate.https://doi.org/10.1029/2024WR037652evaporationtranspirationeddy covarianceempiricalplant hydraulicsmachine learning
spellingShingle Pushpendra Raghav
Mukesh Kumar
Yanlan Liu
Structural Constraints in Current Stomatal Conductance Models Preclude Accurate Prediction of Evapotranspiration
Water Resources Research
evaporation
transpiration
eddy covariance
empirical
plant hydraulics
machine learning
title Structural Constraints in Current Stomatal Conductance Models Preclude Accurate Prediction of Evapotranspiration
title_full Structural Constraints in Current Stomatal Conductance Models Preclude Accurate Prediction of Evapotranspiration
title_fullStr Structural Constraints in Current Stomatal Conductance Models Preclude Accurate Prediction of Evapotranspiration
title_full_unstemmed Structural Constraints in Current Stomatal Conductance Models Preclude Accurate Prediction of Evapotranspiration
title_short Structural Constraints in Current Stomatal Conductance Models Preclude Accurate Prediction of Evapotranspiration
title_sort structural constraints in current stomatal conductance models preclude accurate prediction of evapotranspiration
topic evaporation
transpiration
eddy covariance
empirical
plant hydraulics
machine learning
url https://doi.org/10.1029/2024WR037652
work_keys_str_mv AT pushpendraraghav structuralconstraintsincurrentstomatalconductancemodelsprecludeaccuratepredictionofevapotranspiration
AT mukeshkumar structuralconstraintsincurrentstomatalconductancemodelsprecludeaccuratepredictionofevapotranspiration
AT yanlanliu structuralconstraintsincurrentstomatalconductancemodelsprecludeaccuratepredictionofevapotranspiration