Headline: A multiscale modelling approach for evaluation of urban air quality in Modena (Italy)

A multi-scale modelling system was developed to provide hourly NOx concentrations field at building resolving scale in the urban area of Modena. The WRF-Chem model was employed with aim of reproducing local background concentrations taking into account meteorological and chemical transformation at regional scale, conversely the PMSS modelling system was applied to simulate 3D air pollutant dispersion with a very high-resolution (4 m) on a 6 km x 6 km domain. Modelled NOx concentrations reproduced by this modelling system show a good agreement with observation at both traffic and background urban stations.