Local evaluation of the Interaction between Soil Biosphere Atmosphere soil multilayer diffusion scheme using four pedotransfer functions

The Surface Monitoring Of the Soil Reservoir Experiment (SMOSREX) site is used in this study to evaluate the performance of the Interaction between Soil Biosphere Atmosphere soil multilayer diffusion scheme (ISBA-DF) in reproducing short-term and long-term evolution of soil moisture and temperature profiles, surface energy fluxes, and drainage rate using both the Brooks and Corey and the van Genuchten models describing soil-water retention and conductivity curves. The site consists of a fallow field in southwestern France where intensive measurements were made during the 2001-2007 period. Two sets of four simulations describing homogeneous and heterogeneous soil properties are performed using four continuous pedotransfer functions. ISBA-DF is also compared with the ISBA "force-restore" soil scheme (ISBA-FR) since this version is currently used in several meteorological, hydrological, and/or climate applications. ISBA-DF exhibits a good performance in terms of simulating the soil moisture profile and the surface energy fluxes, especially when heterogeneous soil properties are considered. Its soil moisture dynamic does not depend on the field capacity, which is a clear advantage compared with ISBA-FR. However, it shows some drawbacks in simulating the surface temperature. The Brooks and Corey model exhibits the best skill scores in simulating the soil moisture profile and the surface fluxes compared with the van Genuchten model. Nevertheless, the differences are not significant, and the results on a single site reduce the generality of this intercomparison. Finally, two additional sets of experiments are performed to assess the scheme sensitivity to increasing soil depth and to the soil vertical discretization.