Calibrating soybean parameters in JULES 5.0 from the US-Ne2/3 FLUXNET sites and the SoyFACE-O3 experiment

Authors: LEUNG, FELIX - University Of Exeter; WILLIAMS, KARINA - Met Office; SITCH, STEPHEN - University Of Exeter; TAI, AMOS - The Chinese University Of Hong Kong (CUHK); WILTSHIRE, ANDY - Met Office; GORNALL, JEMMA - Met Office; Ainsworth, Elizabeth - Lisa; ARKEBAUER, TIMOTHY - University Of Nebraska; SCOBY, DAVID - University Of Nebraska

Submitted to: Geoscientific Model Development
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2020
Publication Date: 12/7/2020
Citation: Leung, F., Williams, K., Sitch, S., Tai, A., Wiltshire, A., Gornall, J., Ainsworth, E.A., Arkebauer, T., Scoby, D. 2020. Calibrating soybean parameters in JULES 5.0 from the US-Ne2/3 FLUXNET sites and the SoyFACE-O3 experiment. Geoscientific Model Development. 13(12):6201-6213. https://doi.org/10.5194/gmd-13-6201-2020.
DOI: https://doi.org/10.5194/gmd-13-6201-2020

Interpretive Summary: Ozone is a damaging pollutant to plants and significantly decreases crop yield. Many land surface models do not yet include crop-specific parameters to simulate the effects of ozone pollution on crops. This paper uses data from long-term field experiments of soybean grown at elevated ozone, along with data from a long-term FLUXNET site in Nebraska to parameterize the Joint UK Environment Simulator (JULES) land surface model for inclusion of ozone effects on crops. The newly calibrated version of the model is described in this paper, and can be applied regionally and globally to simulate the impacts of ozone pollution on crop production.

Technical Abstract: Tropospheric ozone (O3) is the third most important anthropogenic greenhouse gas. O3 is detrimental to plant productivity, and it has a significant impact on crop yield. Currently, the Joint UK Land Environment Simulator (JULES) land surface model includes a representation of global crops (JULES-crop), but does not have crop-specific O3 damage parameters, and applies default C3 grass O3 parameters for soybean that underestimates O3 damage. Physiological parameters for O3 damage in soybean in JULES-crop were calibrated against leaf gas-exchange measurements from the Soybean Free-Air-Concentration-Enrichment (SoyFACE) with O3 experiment in Illinois, USA. Other plant parameters were calibrated using an extensive array of soybean observations such as crop height, leaf carbon, etc. and meteorological data from FLUXNET sites near Mead, Nebraska, USA. The yield, aboveground carbon and leaf area index (LAI) of soybean from the SoyFACE experiment were used to evaluate the newly calibrated parameters. The result shows good performance for yield, with the modelled yield being within the spread of the SoyFACE observations. Although JULES-crop is able to reproduce observed LAI seasonality, its magnitude is underestimated. The newly calibrated version of JULES will be applied regionally and globally in future JULES simulations. This study helps to build a state-of-the-art impact assessment model and contribute to a more complete understanding of the impacts of climate change on food production.