EGUsphere EGUsphere EGUsphere EGUsphere Copernicus Publications Göttingen, Germany 10.5194/egusphere-2024-4077 A first calibration of the JULES-crop version 7.4 for rice using the novel O<sub>3</sub>-FACE experiment in China Xu Beiyao https://orcid.org/0000-0002-1230-1850 1 2 Dobbie Steven 2 Yang Huiyi 3 4 Yang Lianxin 5 Jiang Yu 6 Challinor Andrew 2 Williams Karina https://orcid.org/0000-0002-1185-535X 4 7 Wang Yunxia 8 Wang Tijian 1 School of Atmospheric Sciences, Nanjing University, China Institute for Climate and Atmospheric Science, University of Leeds, UK Natural Resources Institute, University of Greenwich, UK Global Systems Institute, University of Exeter, UK Key Lab of Crop Genetics & Physiology of Jiangsu Province, Yangzhou University, China Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, China Met Office, Exeter, UK College of Environmental Science and Engineering, Yangzhou University, China 12 03 2025 2025 1 24 Copyright: © 2025 Beiyao Xu et al. 2025 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://egusphere.copernicus.org/preprints/2025/egusphere-2024-4077/ The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2025/egusphere-2024-4077/egusphere-2024-4077.pdf

Ozone (O<sub>3</sub>) pollution poses an escalating threat to rice production and food security in China, with concentrations projected to rise under future climate scenarios. Accurately quantifying O<sub>3</sub> impacts on rice is thus crucial for informed agricultural planning. This study is the first to utilise Free Air Concentration Enrichment (FACE) observations specific to rice for calibrating a crop model (JULES-crop) and assessing the impacts of O<sub>3</sub>. FACE experiments, which involve growing crops under natural field conditions while exposing them to elevated O<sub>3</sub> levels, provide an ideal approach for studying the effects of O<sub>3</sub> on crops. Utilising data from the only O<sub>3</sub>-FACE facility dedicated to rice, we calibrated physiological and O<sub>3</sub>-response parameters in JULES-crop and evaluated the model against additional independent FACE observations. The calibration establishes this as the first crop model refined with ideal open-air field observations, significantly enhancing its capability to simulate rice growth processes and O<sub>3</sub>-induced yield losses, surpassing the performance of simulations based on the default parameters in JULES-crop. With this newly calibrated model, JULES-crop is now equipped to assess the impacts of O<sub>3</sub> on agriculture, offering a valuable tool to inform mitigation strategies.