Modelling the dispersion of particle numbers in five European cities

J Kukkonen,B R Denby,H A C Denier Van Der Gon,S Lützenkirchen,A Karppinen,T Petäjä,J Douros,M P Keuken,R S Sokhi,S Jonkers,V Singh,I Vouitsis,N Moussiopoulos,Z Samaras,M Karl,L Kangas,M Aarnio,A Manders

doi:10.5194/gmd-9-451-2016

Abstract

Abstract. We present an overview of the modelling of particle number concentrations (PNCs) in five major European cities, namely Helsinki, Oslo, London, Rotterdam, and Athens, in 2008. Novel emission inventories of particle numbers have been compiled both on urban and European scales. We used atmospheric dispersion modelling for PNCs in the five target cities and on a European scale, and evaluated the predicted results against available measured concentrations. In all the target cities, the concentrations of particle numbers (PNs) were mostly influenced by the emissions originating from local vehicular traffic. The influence of shipping and harbours was also significant for Helsinki, Oslo, Rotterdam, and Athens, but not for London. The influence of the aviation emissions in Athens was also notable. The regional background concentrations were clearly lower than the contributions originating from urban sources in Helsinki, Oslo, and Athens. The regional background was also lower than urban contributions in traffic environments in London, but higher or approximately equal to urban contributions in Rotterdam. It was numerically evaluated that the influence of coagulation and dry deposition on the predicted PNCs was substantial for the urban background in Oslo. The predicted and measured annual average PNCs in four cities agreed within approximately ≤ 26 % (measured as fractional biases), except for one traffic station in London. This study indicates that it is feasible to model PNCs in major cities within a reasonable accuracy, although major challenges remain in the evaluation of both the emissions and atmospheric transformation of PNCs.

Highlights

Airborne particulate matter (PM) affects human health and climate (e.g. Smith et al, 2009)
While a large base of scientific information exists on particle mass, especially for PM10 and PM2.5, there are substantially less studies on particle numbers (PNs) and in particular on modelling dispersion of PNs in urban areas (e.g., Kumar et at., 2013)
The contribution of shipping is more dominant in the current inventory, compared with the first European PN emission inventory made in the EU-funded project EUCAARI (Denier van der Gon et al, 2010a; Kulmala et al, 2011)

Summary

Introduction

Airborne particulate matter (PM) affects human health and climate (e.g. Smith et al, 2009). While a large base of scientific information exists on particle mass, especially for PM10 and PM2.5, there are substantially less studies on particle numbers (PNs) and in particular on modelling dispersion of PNs in urban areas (e.g., Kumar et at., 2013). This may be attributed to (i) scarcity of reliable information on emissions, (ii) the greater complexity of physical and chemical atmospheric processes, and (iii) lack of monitoring data of PN. PN measurement techniques are more complex and resource consuming, compared with the measurements of particulate mass fractions

Objectives

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Results

Conclusion