engleski

Regional climate simulations using RegCM4 over Europe and Mediterranean: the impacts of boundary conditions, horizontal resolution and the model time-step

Regional climate model RegCM4 is applied over the EURO-CORDEX domain for the purpose of estimating model performance in the historical climate and as a preparation step for the future climate projections. Previous 12.5 km and 50 km RegCM4 experiments using ERA-Interim as a forcing dataset showed strong sensitivity of e.g. model near- surface temperature and total precipitation to the horizontal resolution. In this study we expand initial set of experiments by forcing RegCM4 using global models HadGEM2-ES, EC-EARTH, MPI-ESM-LR and CNRM-CM5 for the period 1970-2005 at the 50 km resolution and for the period 1970-1974 at the 12.5 km resolution. The model performance in this ensemble of simulation is evaluated against the E- OBS gridded observational dataset. In order to estimate potential impact of the reduced time-step in the 12.5 km simulations, additional set of simulations is performed where RegCM4 at the 50 km resolution used the time-step from the initial 12.5 km simulations (i.e. a change from 150 s to 30 s). The results of this study will provide the basis for the selection of the global model for the extended simulation at the 12.5 km (1970-2005 historical simulation and 2005-2050 using RCP4.5 scenario) and will provide additional insight to the causes of the model systematic errors.

regional climate model; systematic errors; discretization

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