Uncertainty in representation of ecosystem processes in Europe by the Community Land Model v5

<p>Understanding hydrological and biogeochemical ecosystem process variability in response to a changing climate is important to improve land surface models and assess current and future states of ecosystem functioning. However, the representation of spatial heterogeneity of ecosystem processes in state-of-the-art land-surface models has not been evaluated thoroughly until today. Here we compare gross primary production (GPP) and evapotranspiration (ET) simulated by the Community Land Model version 5 (CLM5) for the period 1995-2018 over the Euro-CORDEX domain with in-situ data from eddy-covariance sites as well as remote sensing and reanalysis data. Additionally, we conducted a parameter sensitivity analysis to identify the impact of uncertainty coming from ecosystem parameters (in particular default parameters for given plant functional types) for selected sites in Europe.&#160;</p> <p>&#160;</p> <p>Our results show that GPP and ET variation across hydroclimates show in general a good agreement between CLM5 and remote sensing and reanalysis products. However, both GPP and ET simulated by CLM5 show large differences with measured in-situ data, depending on the ecosystem type. Further, we identify sensitive parameters that will be adjusted to improve ecosystem representation in CLM5 in a future study. This work is important to improve land surface models and parameterization of plant functional types to understand and improve predictions of ecosystem functioning.</p>