Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 10 5 2010 10.5194/acp-10-2475-2010 http://www.atmos-chem-phys.net/10/2475/2010/ http://www.atmos-chem-phys.net/10/2475/2010/acp-10-2475-2010.html http://www.atmos-chem-phys.net/10/2475/2010/acp-10-2475-2010.pdf 2475 2490 2010-03-11 Linking urban aerosol fluxes in street canyons to larger scale emissions B. K. Tay G. B. McFiggans D. P. Jones M. W. Gallagher martin.gallagher@manchester.ac.uk C. Martin P. Watkins R. M. Harrison Centre for Atmospheric Science, SEAES, The University of Manchester, Manchester, M13 9PL, UK School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, P.O. Box 88, Manchester M60 1QD, UK Division of Environmental Health & Risk Management, School of Geography, Earth & Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK In this study we investigate ultrafine particle (UFP) fluxes using a first order eddy viscosity turbulence closure Computational Fluid Dynamics (CFD) model and determine the different factors that influence emissions of UFP into the urban boundary layer. Both vertical turbulent fluxes as well as the fluxes due to mean circulatory flow are shown to contribute to the overall ventilation characteristics of street canyons. We then derive a simple parameterised numerical prediction model for canyon top UFP venting which is then compared with tower based micrometeorological flux measurements obtained during the REPARTEE & CityFlux field experiments. Baik, J. J. and Kim, J. J.: A numerical study of flow and pollutant dispersion characteristics in urban street canyons, J. Appl. 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