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Processes controlling atmospheric dispersion through city centres

  • S. E. Belcher (a1), O. Coceal (a2), E. V. Goulart (a1), A. C. Rudd (a1) and A. G. Robins (a3)...


We develop a process-based model for the dispersion of a passive scalar in the turbulent flow around the buildings of a city centre. The street network model is based on dividing the airspace of the streets and intersections into boxes, within which the turbulence renders the air well mixed. Mean flow advection through the network of street and intersection boxes then mediates further lateral dispersion. At the same time turbulent mixing in the vertical detrains scalar from the streets and intersections into the turbulent boundary layer above the buildings. When the geometry is regular, the street network model has an analytical solution that describes the variation in concentration in a near-field downwind of a single source, where the majority of scalar lies below roof level. The power of the analytical solution is that it demonstrates how the concentration is determined by only three parameters. The plume direction parameter describes the branching of scalar at the street intersections and hence determines the direction of the plume centreline, which may be very different from the above-roof wind direction. The transmission parameter determines the distance travelled before the majority of scalar is detrained into the atmospheric boundary layer above roof level and conventional atmospheric turbulence takes over as the dominant mixing process. Finally, a normalised source strength multiplies this pattern of concentration. This analytical solution converges to a Gaussian plume after a large number of intersections have been traversed, providing theoretical justification for previous studies that have developed empirical fits to Gaussian plume models. The analytical solution is shown to compare well with very high-resolution simulations and with wind tunnel experiments, although re-entrainment of scalar previously detrained into the boundary layer above roofs, which is not accounted for in the analytical solution, is shown to become an important process further downwind from the source.

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Corresponding author

Email address for correspondence:


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Present address: Federal University of Espirito Santo, Vitoria, Brazil.


Present address: Centre for Ecology and Hydrology, Wallingford OX10 8BB, UK.



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Arya, S. P. 1999 Air Pollution Meteorology and Dispersion. Oxford University Press.
Belcher, S. E. 2005 Mixing and transport in urban areas. Phil. Trans. R. Soc. 363, 29472963.
Belcher, S. E., Coceal, O., Hunt, J. C. R., Carruthers, D. J. & Robins, A. G.2013 A review of urban dispersion modelling. Atmospheric Dispersion Modelling Liaison Committee Report ADMLC-R7, Annex B, pp. 94.
Belcher, S. E., Jerram, N. & Hunt, J. C. R. 2003 Adjustment of the atmospheric boundary layer to a canopy of roughness elements. J. Fluid Mech. 488, 369398.
Berkowitz, R. 2000 OSPM – a parameterised street pollution model. J. Env. Moni. Assess. 65, 323331.
Bohnenstengel, S. I., Evans, S., Clark, P. A. & Belcher, S. E. 2011 Simulations of the London urban heat Island. Q. J. R. Meteorol. Soc. 137, 16251640.
Branford, S., Coceal, O., Thomas, T. G. & Belcher, S. E. 2011 Dispersion of a point-source release of a passive scalar through an urban-like array for different wind directions. Boundary-Layer Meteorol. 139, 367394.
Briggs, G. A.1973 Diffusion Estimation for Small Emissions, preliminary draft, Atmospheric Turbulence and Diffusion Laboratory. Available at
Britter, R. E. & Hanna, S. R. 2003 Flow and dispersion in urban areas. Annu. Rev. Fluid Mech. 35, 469496.
Cai, X., Barlow, J. F. & Belcher, S. E. 2008 Dispersion and transfer of passive scalars in and above street canyons – large-eddy simulations. Atmos. Environ. 42, 58855895.
Carpentieri, M., Hayden, P. & Robins, A. G. 2012 Wind tunnel measurements of pollutant turbulent fluxes in urban intersections. Atmos. Environ. 46, 669674.
Carruthers, D. J., Edmunds, H. A., Lester, A. E., McHugh, C. A. & Singles, R. J. 2000 Use and validation of ADMS-urban in contrasting urban and industrial locations. Intl J. Environ. Pollut. 14 (1–6), 364374.
Coceal, O. & Belcher, S. E. 2004 A canopy model of mean winds through urban areas. Q. J. R. Meteorol. Soc. 130, 13491372.
Coceal, O., Dobre, A., Thomas, T. G. & Belcher, S. E. 2007 Structure of turbulent flow over regular arrays of cubical roughness. J. Fluid Mech. 589, 375409.
Coceal, O., Thomas, T. G., Castro, I. P. & Belcher, S. E. 2006 Mean flow and turbulence statistics over groups of urban-like cubical obstacles. Boundary-Layer Meteorol. 121, 491519.
Davidson, M. J., Mylne, K. R., Jones, C. D., Phillips, J. C. & Perkins, R. J. 1995 Plume dispersion through large groups of obstacles – a field investigation. Atmos. Environ. 29, 32453256.
Davidson, M. J., Snyder, W. H., Lawson, R. E. & Hunt, J. C. R. 1996 Wind tunnel simulations of plume dispersion through groups of obstacles. Atmos. Environ. 30, 37153725.
DePaul, F. & Sheih, C. 1986 Measurements of wind velocities in a street canyon. Atmos. Environ. 20, 455459.
Dobre, A., Arnold, S. J., Smalley, R. J., Boddy, J. W. D., Barlow, J. F., Tomlin, A. S. & Belcher, S. E. 2005 Flow field measurements in the proximity of an urban intersection in London, UK. Atmos. Environ. 39, 46474657.
Evans, S., Hudson-Smith, A. & Batty, M.2005 3-D GIS: Virtual London and beyond. Cybergeo, Selection des meilleurs articles de SAGEO 2005, Article 359. Available at
Fernando, H. J. S., Zajic, D., Di Sabatino, S., Dimitrova, R., Hedquist, B. & Dallman, A. 2010 Flow, turbulence, and pollutant dispersion in urban atmospheres. Phys. Fluids 22 (5), 051301.
Goulart, E. V.2012 Flow and dispersion in urban areas. PhD thesis, University of Reading, UK.
Griffiths, R. F. 1994 Errors in the use of the Briggs parameterisation for atmospheric dispersion coefficients. Atmos. Environ. 28, 28612865.
Hall, D. J., Spanton, A. M., Griffiths, I. H., Hargrave, M., Walker, S. & John, C. 2001 The UDM: a puff model for estimating dispersion in urban areas. In Proceedings of 7th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes, Belgirate, Italy, pp. 256260.
Hamlyn, D., Hilderman, T. & Britter, R. 2007 A simple network approach to modelling dispersion among large groups of obstacles. Atmos. Environ. 41, 58485862.
Hilderman, T. & Chong, R.2007 A laboratory study of momentum and passive scalar transport and diffusion within and above a model urban canopy. Contract Report DRDC Suffield CR 2008-025, p. 70.
Macdonald, R. W., Griffiths, R. F. & Cheah, S. C. 1997 Field experiments of dispersion through regular arrays of cubic structures. Atmos. Environ. 31, 783795.
Macdonald, R. W., Griffiths, R. F. & Hall, D. J. 1998 A comparison of results from scaled field and wind tunnel modelling of dispersion in arrays of obstacles. Atmos. Environ. 32, 38453862.
Oke, T. 1987 Boundary Layer Climates. Routledge.
Philips, D. A., Rossi, R. & Iaccarino, G. 2013 Large-eddy simulation of passive scalar dispersion in an urban-like canopy. J. Fluid Mech. 723, 404428.
Rudd, A. C., Robins, A. G., Lepley, J. J. & Belcher, S. E. 2012 An inverse method for determining source characteristics for emergency response applications. Boundary-Layer Meteorol. 144, 120.
Soulhac, L.2000 Modelisation de la dispersion atmospherique a l’interieur de la canopee urbaine. PhD thesis, Ecole Centrale de Lyon.
Soulhac, L., Garbero, V., Salizzoni, P., Mejean, P. & Perkins, R. J. 2009 Flow and dispersion in street intersections. Atmos. Environ. 43, 29812996.
Soulhac, L., Salizzoni, P., Cierco, F.-X. & Perkins, R. 2011 The model SIRANE for atmospheric urban pollutant dispersion. Part I. Presentation of the model. Atmos. Environ. 45, 73797395.
Soulhac, L., Salizzoni, P., Mejean, P., Didier, D. & Rios, I. 2012 The model SIRANE for atmospheric urban pollutant dispersion. Part II. Validation of the model on a real case study. Atmos. Environ. 49, 320337.
Theurer, W., Plate, E. J. & Hoeschele, K. 1996 Semi-empirical models as a combination of wind tunnel and numerical dispersion modelling. Atmos. Environ. 30, 35833597.
Wilf, H. S. 1994 Generating Functionology, 2nd edn. Academic.
Wood, C. R., Arnold, S. J., Balogun, A. A., Barlow, J. F., Belcher, S. E., Britter, R. E., Cheng, H., Dobre, A., Lingard, J. J. N., Martin, D., Neophytou, M., Petersson, F. K., Robins, A. G., Shallcross, D. E., Smalley, R. J., Tate, J. E., Tomlin, A. S. & White, I. R. 2009 Dispersion experiments in central London: the 2007 DAPPLE project. Bull. Am. Meteorol. Soc. 90, 955969.
Yee, E. & Biltoft, C. A. 2004 Concentration fluctuation measurements in a plume dispersing through a regular array of obstacles. Boundary-Layer Meteorol. 111, 363415.
Yee, E., Gailis, R. M., Hill, A., Hilderman, T. & Kiel, D. 2006 Comparison of wind tunnel and water-channel simulations of plume dispersion through a large array of obstacles with a scaled field experiment. Boundary-Layer Meteorol. 121, 389432.
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Processes controlling atmospheric dispersion through city centres

  • S. E. Belcher (a1), O. Coceal (a2), E. V. Goulart (a1), A. C. Rudd (a1) and A. G. Robins (a3)...


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