The Coordinated Regional climate Downscaling EXperiment (CORDEX), endorsed by the World Climate Research Program (WCRP), provides global coordination of Regional Climate Downscaling (RCD) for improved regional climate change adaptation and impact assessment.
In a paper recently published on Meteorology and Athmospheric Physics a team of authors (among them, CMCC researchers E. Bucchignani, L. Cattaneo and P. Mercogliano) present the results of a sensitivity work based on ERA-Interim driven COSMO-CLM simulations over the Middle East-North Africa (CORDEX-MENA) domain. 
The purpose of this study was to ascertain model performances with respect to changes in physical parameters which are mainly related to surface, convection, radiation and cloud parameterizations.

The abstract of the paper:
The results of a sensitivity work based on ERA-Interim driven COSMO-CLM simulations over the Middle East-North Africa (CORDEX-MENA) domain are presented. All simulations were performed at 0.44° spatial resolution. The purpose of this study was to ascertain model performances with respect to changes in physical and tuning parameters which are mainly related to surface, convection, radiation and cloud parameterizations. Evaluation was performed for the whole CORDEX-MENA region and six sub-regions, comparing a set of 26 COSMO-CLM runs against a combination of available ground observations, satellite products and reanalysis data to assess temperature, precipitation, cloud cover and mean sea level pressure. The model proved to be very sensitive to changes in physical parameters. The optimized configuration allows COSMO-CLM to improve the simulated main climate features of this area. Its main characteristics consist in the new parameterization of albedo, based on Moderate Resolution Imaging Spectroradiometer data, and the new parameterization of aerosol, based on NASA-GISS AOD distributions. When applying this configuration, Mean Absolute Error values for the considered variables are as follows: about 1.2°C for temperature, about 15 mm/month for precipitation, about 9% for total cloud cover, and about 0.6 hPa for mean sea level pressure.

Read the integral version of the paper:

Bucchignani E., Cattaneo L. , Panitz H., Mercogliano P.
Sensitivity analysis with the regional climate model COSMO-CLM over the CORDEX-MENA domain
2015, Meteorology and Atmospheric Physics, DOI: 10.1007/s00703-015-0403-3