Middle East - North Africa (MENA) region is characterized by increasing energy demand combined with high energy costs and short reserves of fossil fuels. Hence, the knowledge of the spatial and temporal variability of Global Horizontal Irradiance (GHI) is necessary for assessing the efficiency of alternative energy sources. In this study, satellite retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS, versions 6 and 6.1) and radiative transfer model simulations are used to evaluate the effect of aerosol optical properties on GHI under cloud-free conditions in the MENA region. The modeled GHI is validated against ground-based measurements at six MENA sites. Due to induced uncertainties in modeled GHIs, two site-adaptation methodologies (Empirical Quantile Mapping-EQM and Linear Least Squares-LIN) are further evaluated to diminish the systematic and dispersion errors. EQM is revealed to be more efficient, causing a significant correction to the statistical distribution of the modeled GHI. For almost all sites, modeled GHI values present the best statistical results when MODIS version 6.1 is used. (C) 2020 Elsevier Ltd. All rights reserved.