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1.
CityFlux perfluorocarbon tracer experiments
Fredrik K Petersson, Damien Martin, Iain R White, Stephen J Henshaw, Graham Nickless, Ian Longley, Carl J Percival, Martin Gallagher, Dudley E. Shallcross, 2010, izvirni znanstveni članek

Opis: In June 2006, two perfluorocarbon tracer experiments were conducted in central Manchester UK as part of the CityFlux campaign. The main aim was to investigate vertical dispersion in an urban area during convective conditions, but dispersion mechanisms within the street network were also studied. Paired receptors were used in most cases where one receptor was located at ground level and one at roof level. One receptor was located on the roof of Portland Tower which is an 80m high building in central Manchester. Source receptor distances in the two experiments varied between 120 and 600 m. The results reveal that maximum concentration was sometimes found at roof level rather than at ground level implying the effectiveness of convective forces on dispersion. The degree of vertical dispersion was found to be dependent on source receptor distance as well as on building height in proximity to the release site. Evidence of flow channelling in a street canyon was also found. Both a Gaussian profile and a street network model were applied and the results show that the urban topography may lead to highly effective flow channelling which therefore may be a very important dispersion mechanism should the right meteorological conditions prevail. The experimental results from this campaign have also been compared with a simple urban dispersion model that was developed during the DAPPLE framework and show good agreement with this. The results presented here are some of the first published regarding vertical dispersion. More tracer experiments are needed in order to further characterise vertical concentration profiles and their dependence on, for instance, atmospheric stability. The impact of urban topography on pollutant dispersion is important to focus on in future tracer experiments in order to improve performance of models as well as for our understanding of the relationship between air quality and public health.
Najdeno v: osebi
Ključne besede: air quality, atmospheric chemistry, concentration (composition), convective system, dispersion, public health, street canyon, tracer, urban area
Objavljeno: 18.07.2019; Ogledov: 429; Prenosov: 0
.pdf Polno besedilo (1,07 MB)

2.
Atmospheric chemistry and physics in the atmosphere of a developed megacity (London): An overview of the REPARTEE experiment and its conclusions
Gavin J Phillips, Carole Helfter, Chiara F Di Marco, Eiko Nemitz, Fay Davies, Janet F Barlow, Tyrone Dunbar, Iain R White, Dudley E Shallcross, Stephen J Henshaw, K Fredrik Peterson, Brian Davison, Damien Martin, Ben Langford, C Nicholas Hewitt, Stephen M Ball, Justin M Langridge, A K Benton, Roderick L Jones, Paul I Williams, John Whitehead, Martin W Gallagher, Claire Martin, James R Dorsey, Hugh Coe, James D Allan, William J Bloss, Alistair J Thorpe, David C S Beddows, Manuel DallOsto, Roy M Harrison, Steven Smith, 2012, pregledni znanstveni članek

Opis: The Regents Park and Tower Environmental Experiment (REPARTEE) comprised two campaigns in London in October 2006 and October/November 2007. The experiment design involved measurements at a heavily trafficked roadside site, two urban background sites and an elevated site at 160-190 m above ground on the BT Tower, supplemented in the second campaign by Doppler lidar measurements of atmospheric vertical structure. A wide range of measurements of airborne particle physical metrics and chemical composition were made as well as measurements of a considerable range of gas phase species and the fluxes of both particulate and gas phase substances. Significant findings include (a) demonstration of the evaporation of traffic-generated nanoparticles during both horizontal and vertical atmospheric transport; (b) generation of a large base of information on the fluxes of nanoparticles, accumulation mode particles and specific chemical components of the aerosol and a range of gas phase species, as well as the elucidation of key processes and comparison with emissions inventories; (c) quantification of vertical gradients in selected aerosol and trace gas species which has demonstrated the important role of regional transport in influencing concentrations of sulphate, nitrate and secondary organic compounds within the atmosphere of London; (d) generation of new data on the atmospheric structure and turbulence above London, including the estimation of mixed layer depths; (e) provision of new data on trace gas dispersion in the urban atmosphere through the release of purposeful tracers; (f) the determination of spatial differences in aerosol particle size distributions and their interpretation in terms of sources and physico-chemical transformations; (g) studies of the nocturnal oxidation of nitrogen oxides and of the diurnal behaviour of nitrate aerosol in the urban atmosphere, and (h) new information on the chemical composition and source apportionment of particulate matter size fractions in the atmosphere of London derived both from bulk chemical analysis and aerosol mass spectrometry with two instrument types.
Najdeno v: osebi
Ključne besede: megacity, trace gas, urban atmosphere, atmospheric transport, chemical composition, aerosol
Objavljeno: 18.07.2019; Ogledov: 471; Prenosov: 0
.pdf Polno besedilo (4,66 MB)

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