Future Emission Scenario Analysis over Rome Urban Area Using Coupled Traffic Assignment and Chemical Transport Models

The city of Rome is characterized by high ozone, NO2 and PM10 levels claiming for the implementation of emission control strategies to improve the air quality and to decrease the risks of health effects on inhabitants. In this perspective an atmospheric modelling system based on the chemical transport model FARM has been applied for the year 2005 over a nested domain including the metropolitan area. To improve the description of local scale atmospheric circulation characteristics, observational meteorological data are analysed using the Isentropic Analysis package (ISAN). Since urban traffic emissions represent a relevant source of pollutants, hourly emissions coming from this sector have been estimated by means of a traffic assignment model, based on a source-destination approach, coupled with an emission model based on COPERT-3 methodology. The emissions from the other sectors have been derived from the national inventory and then disaggregated at the municipal level. The analysis of model results for the year 2005 against experimental data reveals a good agreement suggesting the use of the modelling system to study the impact on the air quality of different emission control strategies at both regional and urban scales. The 2010 has been considered as the future year base case scenario and the traffic limitation within the Rome urban core has been considered as an emission control action. The impact of this emission scenario has been then analysed by means of a semi-empiric approach: a significant decrease of PM10 and NO2 yearly average concentrations is expected to occur at urban traffic stations while the minimum reduction is expected at urban background and rural stations.