ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-12-3065-2012 Atmospheric chemistry and physics in the atmosphere of a developed megacity (London): an overview of the REPARTEE experiment and its conclusions Harrison R. M. 1 2 Dall'Osto M. 1 3 Beddows D. C. S. 1 Thorpe A. J. 1 4 Bloss W. J. 1 Allan J. D. 5 6 Coe H. 5 Dorsey J. R. 5 6 Gallagher M. 5 Martin C. 5 Whitehead J. 5 Williams P. I. 5 6 Jones R. L. 7 Langridge J. M. 7 8 Benton A. K. 7 9 Ball S. M. 10 Langford B. 11 12 Hewitt C. N. 11 Davison B. 11 Martin D. 13 Petersson K. F. 13 Henshaw S. J. 13 White I. R. 13 Shallcross D. E. 13 Barlow J. F. 14 Dunbar T. 14 Davies F. 15 Nemitz E. 12 Phillips G. J. 12 16 Helfter C. 12 Di Marco C. F. 12 Smith S. 17 National Centre for Atmospheric Science, Division of Environmental Health & Risk Management, School of Geography, Earth & Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK Department of Environmental Sciences/Center of Excellence in Environmental Studies, King Abdulaziz University, Jeddah, 21589, Saudi Arabia Institute of Environmental Assessment and Water Research (IDǼA), Consejo Superior de Investigaciones Científicas (CSIC), C/LLuis Solé i Sabarís S/N 08028 Barcelona, Spain AECOM, Enterprise House, 160 Croydon Road, Beckenham, Kent, BR3 4DE, UK Centre for Atmospheric Science, School of Earth, Atmospheric & Environmental Sciences, The University of Manchester, Williamson Building, Oxford Road, Manchester M13 9PL, UK National Centre for Atmospheric Science, School of Earth, Atmospheric & Environmental Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL, UK Centre for Atmospheric Science, Chemistry Department, University of Cambridge, Cambridge, CB2 1EW, UK Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado and NOAA Earth System Research Laboratory, Chemical Sciences Division, Boulder, CO, USA British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK Department of Chemistry, University of Leicester, Leicester LE1 7RH, UK Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK Centre for Ecology & Hydrology, Bush Estate, Penicuik, Midlothian, EH26 0QB, UK Atmospheric Chemistry Research Group (ACRG), School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK Department of Meteorology, University of Reading, Earley Gate, P.O. Box 243, Reading RG6 6B, UK School of Environment and Life Sciences, Peel Building, University of Salford, Salford, Greater Manchester, M5 4WT, UK Max Planck Institute for Chemistry, Joh.-Joachim-Becher-Weg 27, 55128 Mainz, Germany Department of Earth Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 0EX, UK 30 03 2012 12 6 3065 3114 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/12/3065/2012/acp-12-3065-2012.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/12/3065/2012/acp-12-3065-2012.pdf

The <b>RE</b>gents <b>PAR</b>k and <b>T</b>ower <b>E</b>nvironmental <b>E</b>xperiment (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.

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