Modelling the dispersion of particle numbers in five European cities

Abstract

We have presented an overview of the modelling of particle number concentrations (PNC’s) in five major European cities, namely Helsinki, Oslo, London, Rotterdam and Athens, in 2008. We have presented emission inventories of particle numbers both on urban and European scales, atmospheric dispersion modelling of PNC’s in the cities and on a European scale, and evaluated the predicted results against available measured PNC’s. The concentrations of PN in the selected cities were mostly influenced by the emissions from local vehicular traffic. However, harbor and airport activities can also have a substantial influence on the PN concentrations. There was a substantial variation in the performance of the models from site to site, when compared with the available measurements, both regarding the annual average concentrations, and the temporal correlation of the hourly time series. In the future, more accurate emission inventories and emission factors will be needed for the relevant source categories. More long-term measurements of PNC’s will also be needed in various urban locations.