Sensitivity of simulated climate over the MENA region related to different land surface schemes in the WRF model

The effects of different land surface scheme (LSS) implementations on the simulated climate of the Middle East and North Africa (MENA) have been investigated with the Weather Research and Forecasting (WRF) regional model. Six simulations were carried out using four different LSSs (Noah, NoahMP, CLM, RUC) for the period 2000-2010, driven by ERA-Interim meteorological reanalyses at a horizontal resolution of 50 km. Deviations of key surface climate variables, radiation, and turbulent fluxes from the different LSS runs are presented relative to the default Noah scheme. The simulated annual mean climate variables in the MENA (indicating uncertainty) range from 0.7 to 2.4(circle)C for air temperature, 2.0 to 3.4(circle)C for land temperature, and 5 to 25 mm/month (54-65%) for precipitation. The Noah scheme deviates less than - 1 W/m(2)from the domain-wide surface energy balance and the NoahMP less than - 2 W/m(2), while for CLM and RUC the deviation is 3-4 W/m(2). Considering the differences among the surface energy balance from the various LSSs compared to the reference Noah, a surface climate response is calculated, and average LSS-induced climate sensitivity is derived for the air (and land) temperature of 0.1(circle)C per W/m(2)and - 6 mm per W/m(2)for precipitation. The LSS-induced range in the modelled climate is of similar magnitude to the climate change projection estimates for the region, which highlights the importance of carefully selecting a land surface scheme in the regional climate simulations.