###### Abstract
There appear to have been no major changes in dust activity over the past three decades over North Africa, the Middle East and South America, whereas there have been substantial changes in the US high plains, central Asia and Australia [17]. Over the Northern Hemisphere, the south of Europe, the Caribbean zone, and Central to East Asia are particularly affected by dust outbreaks leading to PM\({}_{10}\) exceedances [18; 19]. From the Rocky Mountains to the central plains of USA, dust storms can also occur and lead to very high PM concentration levels in these regions with an intensification of dust storms within the last two decades [20; 21]. Concentration peaks usually occur in early spring in this region. Atmospheric transport of dust is also the major source of iron and other nutrients in ocean [22; 23] and plays an important role on the biogeochemical of marine ecosystems through atmospheric fallouts of dust. Dust storms have economic implications, most usually account for household cleaning and disruption to commercial activities (retail and service industries), air transport and construction [6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24]. Modeling tools, the so-called chemistry transport models (CTMs), have been designed to work from the global to local scales. While global models used to focus on major species such as primary organic matter, sulfates and desert dust, regional models were better developed to predict the secondary organic and inorganic chemistry. Now, regional and global models host similar chemical and physical modules, only the resolution can differ with still different goals. Global CTMs are closely linked to long-term simulations related to climate change issues and to predict monthly or annual evolution of the atmospheric composition, they are commonly used at 1\({}^{\circ}\) to 2\({}^{\circ}\) horizontal resolution to gain computing time. Model forecast of dust outbreaks from Africa to Europe have been evaluated using global and regional chemistry transport models [25]. Models tend to underestimate the long-range transport towards Northern Europe. Their analysis suggests that this is partly due to difficulties in simulating the vertical distribution of dust and horizontal winds. Recently, the NOAA National Centers for Environmental Prediction (NCEP) implemented the NOAA Environmental Modeling System (NEMS) Global Forecast System (GFS) Aerosol Component (NGAC) for global dust forecasting in collaboration with NASA Goddard Space Flight Center (GSFC). NGAC Version 1.0 has been providing five-day dust forecasts at 1\({}^{\circ}\)\(\times\) 1\({}^{\circ}\) resolution [26; 27]. Regional models are usually run for air quality purposes over short periods such as short term forecasts [28] from the regional up to the urban scales (for large cities) with resolution up to 1 or 2 km over large domains [29] showing the added value of finer resolutions to analyze the evolution of anthropogenic pollution plumes issued from source areas. However, using a finer resolution improves the bias but can lead to an impairment of the spatial correlations if the quality of emissions is not improved appropriately [29]. Regional models are also commonly used for policy analysis with yearly simulation in \"scenario modes\" [30] or for climate impact studies [31]. The meteorological conditions influencing the development of deep convection, such as mixing depth, local thermodynamic variability, and wind velocity, are best resolved by models having much higher resolution than current global CTMs [32; 33]. The added value of a finer resolution is also mentioned for models in other recent studies for the transport of dust in West Asia [34; 35]. Differences due to a finer resolution are also associated to the channelization of the dust flow through valleys and the differences in the modeled altitude of the mountains that alters the meteorology and blocks the simulated dust fronts limiting the dust transport.