Abstract

An operational air quality forecast model system has been set up in order to predict air pollutants levels over Italy. The atmospheric circulation is predicted by the Fifth-Generation NCAR/Penn State Mesoscale Model (MM5) and the transport, deposition and chemical reactions are driven by U.S. EPA... Show moreAn operational air quality forecast model system has been set up in order to predict air pollutants levels over Italy. The atmospheric circulation is predicted by the Fifth-Generation NCAR/Penn State Mesoscale Model (MM5) and the transport, deposition and chemical reactions are driven by U.S. EPA's Community Multiscale Air Quality (CMAQ) Modeling System. The system, called AQM-Air Quality Manager, runs using three nested domains with increasingly grid resolution (54 km, 18 km, 6 km), the first one including Northern Africa to take into account also Saharan dust intrusions. MM5 simulations run with initial and boundary conditions provided by NCEP Global Forecast. Saharan dust flux is calculated employing a dedicated algorithm, meteorology-dependent, driven by MM5. The release of aerosol is considered when the friction velocity exceeds a threshold velocity which is a function of the particle diameter, the soil moisture content and the soil roughness length. The quantity of dust released in the atmosphere depends on the soil texture, in particular on the fraction of clay. The anthropogenic and biogenic emission inventory is performed according to CORINAIR methodology using EPER Register data, EMEP emission database, EDGAR information system and the National Emission Inventory. Emission data are elaborated to provide a spatial disaggregation by municipalities over Italian territory. NMVOCs and PM2.5 emissions are speciated by SPECIATE 4.0 integrated in the Sparse Matrix Operator Kernel Emission (SMOKE) system. In AQM SMOKE also provides CMAQ hourly and grid mesh values of biogenic NMVOCs and anthropogenic NOx, NMVOCs, PM10, PM2.5, SOx and CO emissions. The Carbon Bond Mechanism (CB-IV) is employed for solving chemical kinetics. AQM daily provides hourly concentrations for 24/48/72/120 hours, an Air Quality Index to easily inform the population, the comparison of the last forecast with the concentration measured by the local monitoring network and the forecast performance index calculated accordingly to the EU Directive for model evaluation. Show less