Understanding discrepancies in simulated evaporative fluxes across the land biosphere models

Land biosphere models which simulate interactive carbon and vegetation dynamics, are critical for understanding and predicting the water and carbon cycles. However, significant discrepancies exist among models regarding simulated variables, raising questions about the accuracy of the underlying process representations. In this study, we use land biosphere models from the TRENDY (Trends and Drivers of Terrestrial Sources and Sinks of Carbon Dioxide) project to understand the discrepancies in evaporative fluxes, including canopy evaporation, transpiration, evapotranspiration, and soil evaporation. Particularly, we try to understand how we can identify differences in process representation that cause these discrepancies. Initial results suggest that models differ from each other and significantly overestimate or underestimate the sensitivity of fluxes compared to data products such as GLEAM, FLUXCOM-X-BASE, and PML. These findings indicate a critical gap in how current models parametrize the coupling between vegetation structure and evaporative fluxes, which may explain part of the uncertainty in future projections.