Regional Climate Model Validation for Central/Eastern Europe using Hydrostatic vs Non-Hydrostatic Approaches

An open-source regional climate model, namely, the RegCM4.5 (available from the ICTP, Trieste) is used to compare different approaches as well, as different moisture parameterizations. The main goal is to reconstruct as reliable as possible the historical (recent past) regional precipitation characteristics of the Carpathian region located in Central/Eastern Europe. For this purpose, several model experiments at 10 km horizontal resolution were completed for a 10-year-long period (1981–1990) using 0.75° ERA-Interim reanalysis data as initial and boundary conditions. Our simulation matrix consists of hydrostatic and non-hydrostatic runs together with the different treatments of moisture, namely, (i) Subgrid Explicit Moisture Scheme (SUBEX) is used to handle non-convective clouds and precipitation resolved by the model, (ii) the new microphysics scheme allows a proper treatment of mixed-phase clouds and a physically more realistic representation of cloud microphysics and precipitation. In this detailed validation study RegCM outputs are compared to the homogenized, 0.1° resolution CarpatClim data as reference, since the gridded time series are based on the measurements of regular meteorological stations within the Carpathian region (i.e. 44°–50°N, 17°–27°E). On the basis of the results we can conclude that the outputs of the convection permitting simulations (using non-hydrostatic approach) overestimate the precipitation in the mountainous areas, which is greater than in the simulations using the hydrostatic approach.