## 1 Introduction  
The Intergovernmental Panel on Climate Change [1] has recognized mineral dust as the main component of atmospheric aerosols, and considered it as an 'essential climate variable'. It may be defined as one of the largest natural aerosol sources and influencing significantly the weather and climate system [2]. Aerosol particles influence climate by modifying directly the global energy budget by scattering and absorbing long- and short-wave radiation [3] and interacting with clouds modifying the development and occurrence of precipitation (indirect effects). The Sahara Desert contributes to the total emission of dust to more than half of the global [4]. Strong convective structures generated by the intense surface heating raise the dust particles for thousands of meters into the troposphere, where they are finally transported at the continental and intercontinental scales [5]. It has been estimated that 10% of the Saharan dust amount is transported across the Mediterranean Sea to Europe [6; 7] in episodic storms or following periodic patterns [8; 9]. In recent studies [10; 11], it was reported an average contribution between 30% and 40% to the optical depth over different cities in southern Europe. The most important parameter describing the level of columnar aerosols in the atmosphere is the Aerosol Optical Depth (AOD). AOD may be measured at ground level with a sun-photometer or from space by Spectroradiometer (e.g., Moderate Resolution Imaging Spectroradiometer, MODIS). At this purpose, a federation of ground-based sun-photometers has been established by NASA and the French CNRS. It includes nearly 1000 sun photometers distributed worldwide within the Aerosol Robotic Network (AERONET) [12] whose data are processed according to the same aerosol retrieval algorithms [13; 14]. On the other side, AOD measurements from space started in 1999 by NASA with the launch of the Terra spacecraft that is carrying the MODIS sensor. The characterization of atmospheric aerosol is a core of the MODIS mission [15] and the AOD still represents the most robust aerosol physical parameter derived from space. To complement measurements, numerical modeling may be considered a useful approach to study the dust transport from the Saharan arid and semi-arid regions toward the Mediterranean area, allowing a comprehensive understanding of the dust intrusions and their effects on air quality [16] and human health [17]. The Weather Research and Forecasting model coupled with chemistry (WRF-Chem; [18]) has been previously used by many research groups to study this argument, among the others we may cite [PERSON] et al. [19] that studied the influence of biomass burning during summertime over the eastern Mediterranean, [PERSON] et al. [20] who investigated an intense photochemical activity and their impact on air quality over the eastern Mediterranean, [PERSON] et al. [21] who evaluated dust extinction and vertical profiles with different dust emission schemes into the WRF-Chem (v4.02) model over North Africa, and [PERSON] [22] and [PERSON] et al. [23] that evaluated the model performance in the simulation of dust concentrations over an eastern Asia domain using different dust emission formulations. Previous studies of the WRF-Chem reproduction of the AOD over the Mediterranean area have been performed by [PERSON] et al. [24] that made a sensitivity analysis over the broader Mediterranean regions of the WRF-Chem (V3.6.1) model to different dust emission parametrization, by [PERSON] et al. [9; 25], that evaluated the different dust emission schemes in the same version of the WRF-Chem model and by [PERSON] et al. [26] that implemented a dust wet deposition scheme in a dust module of WRF-Chem (V3.8). Experimental data of mineral dust deposition are useful to improve the understanding of deposition processes itself but also to support the development and parameterizations of more sophisticated, size dependent deposition schemes in the WRF-Chem model.