Akhabue et al. (2026) Assessing JULES Across Bioclimatic Domains Through a Pan‐African Flux Tower Evaluation: Insights Into Controls on Gross Primary Productivity, Ecosystem Respiration, and Evapotranspiration Biases

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Identification

• Journal: Journal of Advances in Modeling Earth Systems
• Year: 2026
• Date: 2026-10-01
• Authors: Enimhien F. Akhabue, Andrew M. Cunliffe, Karina Williams, Anna Harper, Songyan Zhu, Petra Brigitte Holden, Jonas Ardö, Mika Aurela, Jérôme Demarty, Frédéric Dô, Jordi Etchanchu, Mangaliso J.S. Gondwe, Carole Helfter, Laurent Kergoat, Giacomo Nicolini, Yann Nouvellon, Maria Carolina Duran Rojas, Olivier Roupsard, Torbern Tagesson, Ville Vakkari, Pieter Gideon van Zyl, Aleksander Więckowski
• DOI: 10.1029/2026ms005888

Research Groups

• University of Oxford, Department of Physics
• University of Reading, Department of Meteorology
• National Centre for Atmospheric Science (NCAS)

Short Summary

This study evaluates the Joint UK Land Environment Simulator (JULES) using eddy covariance observations from 16 flux towers across Africa's diverse hydroclimatic gradients. The results highlight systematic limitations in simulating ecosystem respiration and interannual variability of gross primary productivity.

Objective

• Evaluate the performance of JULES across major African ecosystem types, focusing on gross primary productivity (GPP), ecosystem respiration (Reco), and evapotranspiration.

Study Configuration

• Spatial Scale: Continental scale, covering Africa's diverse hydroclimatic gradients.
• Temporal Scale: Long-term monitoring, with data spanning multiple years to capture interannual variability.

Methodology and Data

• Models used: Joint UK Land Environment Simulator (JULES)
• Data sources: Eddy covariance observations from 16 flux towers across Africa

Main Results

• JULES reproduced broad seasonal dynamics of carbon and water fluxes but showed systematic limitations in simulating Reco and interannual variability of GPP.
• Model performance differed among ecosystem types, with wetlands exhibiting large model‐observation mismatches and cropland sites showing GPP overestimation linked to excessive simulated leaf area index.

Contributions

• This study provides a comprehensive regional evaluation of JULES across Africa's diverse hydroclimatic gradients, highlighting the importance of strengthening benchmarking across underrepresented African ecosystems.
• The results identify hydroclimatic regimes where model development should be prioritized and emphasize the need for improved representation of soil hydrology and vegetation water stress processes.

Funding

• NERC (Natural Environment Research Council) - NE/R016429/1
• European Union's Horizon 2020 research and innovation programme under grant agreement No. 730944

Citation

@article{Akhabue2026Assessing,
  author = {Akhabue, Enimhien F. and Cunliffe, Andrew M. and Williams, Karina and Harper, Anna and Zhu, Songyan and Holden, Petra B. and Ardö, Jonas and Aurela, Mika and Demarty, Jérôme and Dô, Frédéric and Etchanchu, Jordi and Gondwe, Mangaliso J.S. and Helfter, Carole and Kergoat, Laurent and Nicolini, Giacomo and Nouvellon, Yann and Rojas, Maria Carolina Duran and Roupsard, Olivier and Tagesson, Torbern and Vakkari, Ville and Zyl, Pieter Gideon van and Więckowski, Aleksander},
  title = {Assessing JULES Across Bioclimatic Domains Through a Pan‐African Flux Tower Evaluation: Insights Into Controls on Gross Primary Productivity, Ecosystem Respiration, and Evapotranspiration Biases},
  journal = {Journal of Advances in Modeling Earth Systems},
  year = {2026},
  doi = {10.1029/2026ms005888},
  url = {https://doi.org/10.1029/2026ms005888}
}