Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 9 5 2009 10.5194/acpd-9-18065-2009 http://www.atmos-chem-phys-discuss.net/9/18065/2009/ http://www.atmos-chem-phys-discuss.net/9/18065/2009/acpd-9-18065-2009.html http://www.atmos-chem-phys-discuss.net/9/18065/2009/acpd-9-18065-2009.pdf 18065 18112 2009-09-01 Linking aerosol fluxes in street canyons to urban city-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 and Risk Management, School of Geography, Earth and 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 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 and CityFlux field experiments. Baik,~J J. and Kim,~J J.: On the escape of pollutants from urban street canyons, Atmos. Environ., 36, 527–536, 2002. 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