Sensitivity of summer precipitation simulated by the CLM with respect to initial and boundary conditions

The knowledge of the uncertainty resulting from the sensitivity of a regional climate model to physical parameterisation schemes, horizontal resolution, domain size and location, as well as to initial and boundary conditions is crucial for the interpretation of model results, e.g. for dynamical downscaling of global climate predictions. In this study, we assess some of these aspects by investigating daily precipitation statistics simulated by the regional climate model CLM (Climate version of the Local Model). Different sensitivity experiments related to initialisation date, domain size and location and to the lateral boundary forcing have been performed for the summer of 1974. The evaluation domain is Germany, located approximately in the centre of the model domain. Comparisons to the control run show that the spatially averaged precipitation statistics can be significantly affected by this modification, not only in specific regions, but also in entire Germany. The results also indicate that the strength of the lateral boundary forcing has a crucial influence oil the simulated characteristics.