Assessment of the JULES-crop model for simulating sugarcane growth in Brazil

Abstract:

Sugarcane is the main source of sugar in the world and has an important role in bioenergy production in tropical regions. Bioethanol and electricity from sugarcane biomass comprise a significant share of the energy matrix in Brazil, where over 40% of global sugarcane production is cropped. Land surface models (LSM) are important tools to understand and quantify the impacts of climate and adaptation strategies on crop productivity, whilst considering the feedback impacts of croplands on weather and climate. The JULES-crop model is a parameterization of crops within the Joint UK Land Environment Simulator (JULES), an LSM extensively used for assessing the impact of modifying a particular process on the ecosystem as a whole. Here, we provide the first parameterization and evaluation of the JULES-crop model for sugarcane. A dataset of field experiments composed by soil moisture (SM), latent heat (LE) fluxes and biomass across Brazil was used to parameterize and evaluate JULES-crop, testing model assumptions and making appropriate input parameter choices. Results of a local sensitivity analysis showed that the order of importance of JULES-crop’s parameters are those grouped in (1) Biomass Partitioning; (2) Development; (3) Structure and Composition and (4) Roots and Water Stress. The model overpredicted biomass and crop components (e.g. LAI, height) in drier environments, whereas the performance of JULES-crop’s simulations of biomass, LE and SM are comparable to widely used process-based models in wet regions. We use the results to understand model capabilities and identify improvement opportunities for next versions. The parameterization here provided could be used to set up model runs for other sites under current and future climate and study different adaptation strategies.