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The Barcelona Supercomputing Center (BSC) is the National Supercomputer Facility in Spain, hosting MareNostrum, one of the most powerful Supercomputers in Europe. The Earth Sciences Department of BSC operates daily regional dust and air quality forecasts and conducts intensive modelling research for short-term operational prediction. This contribution summarizes the latest developments and current activities in the field of sand and dust storm modelling and forecasting. 1. Dust modelling and forecasting at BSC The Earth Sciences Department of BSC maintains dust forecast operations with the Dust REgional Atmospheric Model (DREAM) and conducts modelling research and developments for short-term prediction. BSC-DREAM [1] predicts the atmospheric life cycle of the eroded desert dust and was developed as a pluggable component of the Eta/NCEP (National Centers for Environmental Prediction) model. BSC-DREAM solves the Euler-type partial differential non-linear equation for dust mass continuity and it is fully inserted as one of the governing prognosis equations in the atmospheric Eta/NCEP atmospheric model equations [2,3,4,5,6,7,8,9,10]. BSC-DREAM simulates all the major processes of the atmospheric dust cycle. During model integration, calculation of the surface dust injection fluxes is made over the model grid points declared as deserts. Once injected into the air, dust aerosol is driven by the atmospheric model variables: by turbulent parameters in the early stage of the process when dust is lifted from the ground to the upper levels; by model winds in the later phases of the process when dust travels away from the sources; finally, by thermodynamic processes and rainfall of the atmospheric model and land cover features which provide wet and dry deposition of dust over the Earth surface. One of the key components of the dust model is the treatment of the sourcing terms in the concentration continuity equation. Failure to adequately simulate/predict the production phase of the dust cycle leads to wrong representation of all other dust processes in the model. Therefore, special WMO/GEO Expert Meeting on an International Sand and Dust Storm Warning System IOP Publishing IOP Conf. Series: Earth and Environmental Science 7 (2009) 012013 doi:10.1088/1755-1307/7/1/012013 c © 2009 IOP Publishing Ltd 1 attention is made to properly parameterize dust production phase. Wind erosion of the soil in BSCDREAM parameterization scheme is controlled mainly by the following factors: type of soil, type of vegetation cover, soil moisture content, and surface atmospheric turbulence. In the model, grid points acting as desert dust sources are specified using arid and semiarid categories of the global USGS 1-km vegetation data set. Another data participating in dust production calculations is the FAO 4-km global soil texture data set from which particle size parameters are evaluated. The main general features of the model are listed below: • Dust production scheme with introduced viscous sub-layer [11,6]. • 8 particle size bin distribution. • Soil wetness effects on dust production [12]. • Dry deposition [13] and below cloud scavenging. • Horizontal and vertical advection, turbulent and lateral diffusion [6] represented as for other scalars in the Eta/NCEP model. • Dust radiative feedbacks on meteorology [14]. Eight size transport bins between 0.1 and 10 μm are considered. In this interval, the aerosol effects on solar radiation are the most significant. Within each transport bin, dust is assumed to have timeinvariant, sub-bin log-normal distribution [15] employing the transport mode with mass median diameter of 2.524 μm [16] and geometric standard deviation 2.0 [17]. The analytic sub-bin distribution allows accurate prescription of physical and optical properties known to vary across the bin width. Since there are not yet satisfactory three-dimensional dust concentration observations, the initial state of dust concentration in the model is defined by the 24-hour forecast from the previous-day model run. The model at the starting day is run using “cold start” conditions, i.e., the zeroconcentration initial state. The model needs about 2-3 days for spinning up and for establishing reliable dust concentration conditions. (a) (b) Figure 1. Northern Africa-Europe-Mediterranean-Middle East (a) and East-Asia (b) forecast domains of BSC-DREAM. BSC-DREAM has been delivering operational dust 72h forecasts over North Africa-EuropeMediterranean (which include North of Africa, the Mediterranean basin, Middle East and Europe) and Asia regions (figure 1) in the last years (http://www.bsc.es/projects/earthscience/DREAM). The operational resolution is 0.3ox0.3o and 24 layers up to 15 km in the vertical. WMO/GEO Expert Meeting on an International Sand and Dust Storm Warning System IOP Publishing IOP Conf. Series: Earth and Environmental Science 7 (2009) 012013 doi:10.1088/1755-1307/7/1/012013