Soil moisture–precipitation feedbacks in Central Europe: Fully coupled WRF-Hydro simulations evaluated with cosmic-ray neutron soil moisture measurements

The skill of regional climate models partly relies on their ability to represent land–atmosphere feedbacks in a realistic manner, through the coupling with a land surface model. However, these models often suffer from insufficient or erroneous information on soil hydraulic parameters. In this study, the fully coupled land–atmosphere model WRF-Hydro driven with ERA5 reanalysis is employed to reproduce the regional atmospheric conditions over Central Europe with a horizontal resolution of 4 km for the period 2017–2020. Simulated soil moisture is compared with data from cosmic-ray neutron sensors (CRNS) at three terrestrial environmental observatories of the TERENO network. Soil hydraulic parameters from the European digital soil dataset EU-SoilHydroGrids, together with hydraulic conductivity functions from the Campbell and van Genuchten–Mualem models, are used to test the impact of different representations of soil infiltration on modeled land–atmosphere feedbacks. An updated method to disentangle the proportion of convective precipitation being favored over wet, dry and mixed soils is provided, in order to shed more light on the soil moisture–precipitation feedback mechanism. It is found that WRF-Hydro with van Genuchten–Mualem and EU-SoilHydroGrids best reproduces CRNS soil moisture daily variations, in association with enhanced soil moisture in the root zone and a larger proportion of convective precipitation favored over wet soils. This study demonstrates the importance of adequately considering infiltration processes to realistically reproduce land–atmosphere feedbacks.