Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 7 1 2007 10.5194/acp-7-167-2007 http://www.atmos-chem-phys.net/7/167/2007/ http://www.atmos-chem-phys.net/7/167/2007/acp-7-167-2007.html http://www.atmos-chem-phys.net/7/167/2007/acp-7-167-2007.pdf 167 181 2007-01-12 Free radical modelling studies during the UK TORCH Campaign in Summer 2003 K. M. Emmerson N. Carslaw nc12@york.ac.uk D. C. Carslaw J. D. Lee G. McFiggans W. J. Bloss T. Gravestock D. E. Heard J. Hopkins T. Ingham M. J. Pilling S. C. Smith M. Jacob P. S. Monks Environment Department, University of York, York, YO10 5DD, UK Institute for Transport Studies, University of Leeds, Leeds, LS2 9JT, UK Department of Chemistry, University of York, York, YO10 5DD, UK School of Earth, Atmospheric and Environmental Science, University of Manchester, Manchester, M60 1QD, UK School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK Department of Chemistry, University of Leicester, Leicester, LE1 7RH, UK now at: IÖZ (Interdisciplinary Environmental Research Centre), TU Bergakademie Freiberg, Brennhausgasse 14, 09599 Freiberg, Germany now at: School of Earth and Environment, University of Leeds, LS2 9JT, UK The Tropospheric ORganic CHemistry experiment (TORCH) took place during the heatwave of summer 2003 at Writtle College, a site 2 miles west of Chelmsford in Essex and 25 miles north east of London. The experiment was one of the most highly instrumented to date. A combination of a large number of days of simultaneous, collocated measurements, a consequent wealth of model constraints and a highly detailed chemical mechanism, allowed the atmospheric chemistry of this site to be studied in detail. Between 25 July and 31 August, the concentrations of the hydroxyl radical and the hydroperoxy radical were measured using laser-induced fluorescence at low pressure and the sum of peroxy radicals was measured using the peroxy radical chemical amplifier technique. The concentrations of the radical species were predicted using a zero-dimensional box model based on the Master Chemical Mechanism version 3.1, which was constrained with the observed concentrations of relatively long-lived species. The model included a detailed parameterisation to account for heterogeneous loss of hydroperoxy radicals onto aerosol particles. Quantile-quantile plots were used to assess the model performance in respect of the measured radical concentrations. On average, measured hydroxyl radical concentrations were over-predicted by 24%. Modelled and measured hydroperoxy radical concentrations agreed very well, with the model over-predicting on average by only 7%. The sum of peroxy radicals was under-predicted when compared with the respective measurements by 22%. Initiation via OH was dominated by the reactions of excited oxygen atoms with water, nitrous acid photolysis and the ozone reaction with alkene species. Photolysis of aldehyde species was the main route for initiation via HO₂ and RO₂. Termination, under all conditions, primarily involved reactions with NO_x for OH and heterogeneous chemistry on aerosol surfaces for HO₂. The OH chain length varied between 2 and 8 cycles, the longer chain lengths occurring before and after the most polluted part of the campaign. Peak local ozone production of 17 ppb hr^−1 occurred on 3 and 5 August, signifying the importance of local chemical processes to ozone production on these days. On the whole, agreement between model and measured radicals is good, giving confidence that our understanding of atmospheres influenced by nearby urban sources is adequate. Alicke, B., Geyer, A., Hofzumahaus, A., Holland, F., Konrad, S., Pätz, H. W., Schäfer, J., Stutz, J., Volz-Thomas, A., and Platt, U.: OH formation by HONO photolysis during the BERLIOZ experiment, J. Geophys. Res., 108, doi:10.1029/2001JD000579, 2003. Atkinson, R.: Atmospheric chemistry of VOCs and NO$_x$, Atmos. Env., 34, 2063–2101, 2000. Bloss, W. J., Gravestock, T. J., Heard, D. E., Ingham, T., Johnson, G. P., and Lee, J. D.: Application of a compact all solid-state laser system to the in situ detection of atmospheric OH, HO₂, NO and IO by laser-induced fluorescence, J. Env. Monitoring, 5, 21–28, 2003. Brasseur, G. P., Hauglustaine, D. A., Walters, S., Rasch, P. J., Muller, J.-F., Granier, C., and Tie, X. X:. MOZART, a global chemical transport model for ozone and related chemical tracers. 1. Model description, J. Geophys. Res., 103, 28 265–28 289. 1998. Carslaw, N., Creasey, D. J., Heard, D. E., Lewis, A. C., McQuaid, J. B., Pilling, M. J., Monks, P.S., Bandy, B. J., and Penkett, S. A.: Modelling OH, HO₂ and RO₂ radicals in the marine boundary layer. 1. Model construction and comparison with field measurements, J. Geophys. Res., 104, 30 241–30 255, 1999. Carslaw, N., Creasey, D. J., Harrison, D., Heard, D. E., Hunter, M. C., Jacobs, P. J., Jenkin, M. E., Lee, J. D., Lewis, A. C., Pilling, M. J., Saunders, S. M., and Seakins, P. W.: Modelling OH and HO₂ radicals in a forested region of north-western Greece, Atmos. Env., 35, 4725–4737, 2001. Clemitshaw, K. C., Carpenter, L. J., Penkett, S. A., and Jenkin, M. E.: A calibrated peroxy radical chemical amplifier for ground-based tropospheric measurements, J. Geophys. Res., 102, 25 405–25 416, 1997. Cleveland, W. S.: Robust Locally Weighted Regression And Smoothing Scatterplots, J. Am. Stat. Assoc., 74(368), 829–836, 1979. Derwent, R. G.: The influence of human activities on the distribution of hydroxyl radicals in the troposphere, Phil. Trans. R. Soc. London, Series A, 354, 501–531, 1996. Edwards, G. D. and Monks, P. S.: Performance of a single monochromator didoe array spectroradiometer for the determination of actinic flux and atmospheric photolysis frequencies, J. Geophys. Res., 108, 8546, doi:10.1029/2002JD002844. Emmerson, K. M., Carslaw, N., Carpenter, L. J., Heard, D. E., Lee, J. D., and Pilling, M. J.: Urban Atmospheric Chemistry during the PUMA Campaign, 1: Comparison of Modelled OH and HO₂ Concentrations with Measurements. J. Atmos. Chem., 52, no 2, 143–164, 2005a. Emmerson, K. M., Carslaw, N., and Pilling, M. J.: Urban Atmospheric Chemistry during the PUMA Campaign. 2: Radical budgets for OH, HO₂ and RO₂, J. Atmos. Chem., 52, no 2, 165–183, 2005b. Fleming, Z. L., Monks, P. S., Rickard, A. R., Bandy, B. J., Brough, N., Green, T. J., Reeves, C. E., and Penkett, S. A.: Seasonal dependence of peroxy radical concentrations at a Northern hemisphere marine boundary layer site during summer and winter: Evidence for photochemical activity in winter, Atmos. Chem. Phys., 6, 5415–5433, 2006. Fleming, Z., Monks, P. S., Rickard, A. R., Heard, D. E., Bloss, W. J., Seakins, P. W., Still, T. J., Sommariva, R., Pilling, M. J., Morgan, R. B., Green, T. J., Brough, N., Mills, G. P., Penkett, S. A., Lewis, A. C., Lee, J. D., Saiz-Lopez, A., and Plane, J. M. C.: Peroxy radical chemistry and the control of ozone photochemistry at Mace Head, Ireland during the summer of 2002, Atmos. Chem. Phys., 6, 2193–2214, 2006. Frost, G. J., Trainer, M., Allwine, G., Buhr, M. P., Calvert, J. G., Cantrell, C. A., Fehsenfeld, F. C., Goldan, P. D., Herwehe, J., Hübler, G., Kuster, W. C., Martin, R., McMillen, R. T., Montzka, S. A., Norton, R. B., Parrish, D. D., Ridley, B. A., Shetter, R. E., Walega, J. G., Watkins, B. A., Westberg, H. H., and Williams, E. J.: Rural Oxidants in the Southern Environment (ROSE) program, J. Geophys. Res., 103, 22 491–22 508, 1998. George, L. A., Hard, T. M., and O'Brien, R. J.: Measurement of free radicals OH and HO₂ in Los Angeles smog, J. Geophys. Res., 104, 11 643–11 655, 1999. Haggerstone, A.-L., Carpenter, L. J., Carslaw, N., and McFiggans, G.: Improved model predictions of HO₂ with gas to particle mass transfer rates calculated using aerosol number size distributions, J. Geophys. Res., 110, D04303, doi:10.1029/2004JD005282, 2005. Harrison, R. M., Yin, J., Tilling, R. M., Cai, X., Seakins, P. W., Hopkins, J. R., Lansley, D. L., Lewis, A. C., Hunter, M. C., Heard, D. E., Carpenter, L. J., Creasey, D. J., Lee, J. D., Pilling, M. J., Carslaw, N., Emmerson, K. M., Redington, A., Derwent, R. G., Ryall, D., Mills, G., and Penkett, S. A.: Measurement and modelling of air pollution and atmospheric chemistry in the U.K. west midlands conurbation: overview of the puma consortium project, Sci. Tot. Env., 360, 5–25, 2006. Heard, D. E., Carpenter, L. J., Creasey, D. J., Hopkins, J. R., Lee, J. D., Lewis, A. C., Pilling, M. J., Seakins, P. W., Carslaw, N., and Emmerson, K. M.: High levels of the hydroxyl radical in the winter urban troposphere, Geophys. Res. Lett., 31, L18112, doi:10.1029/2004GL020544, 2004. Heard, D. E., and Pilling, M. J.: Measurement of OH and HO₂ in the troposphere, Chem. Reviews. 103, 5163–5198, 2003. Holland, F., Hofzumahaus, A., Schäfer, H.-J., Kraus, A., and Pätz, H.-W.: Measurements of OH and HO₂ radical concentrations and photolysis frequencies during BERLIOZ, J. Geophys. Res., 108, doi:10.1029/2001JD001393, 2003. Hopkins, J. R., Lewis, A. C., and Read, K. A.: A Two-column method for long-term monitoring of Non-methane hydrocarbons (NMHC) and oxygenated volatile organic compounds (O-VOCs), J. Env. Monitor., 5, 8–13, 2002. Hough, A. M.: The calculation of photolysis rates for use in global tropospheric modelling studies, AERE Rep. R-13259, Her Majesty's Stn. Off., Norwich, England, 1988. IUPAC.: Summary of evaluated kinetic and photochemical data for atmospheric chemistry, IUPAC Subcommittee for Gas Kinetic Data Evaluation, 2005. Jenkin, M. E., Saunders, S. M., and Pilling, M. J.: The tropospheric degradation of volatile organic compounds: A protocol for mechanism development, Atmos. Env., 31, 81–104, 1997. Jenkin, M. E., Saunders, S. M., Wagner, V., and Pilling, M. J.: Protocol for the development of the Master Chemical Mechanism, MCM v3 (Part B): Tropospheric degradation of aromatic volatile organic compounds, Atmos. Chem. Phys., 3, 181–193, 2003. Konrad, S., Schmitz, Th., Buers, H.-J., Houben, N., Mannschreck, K., Mihelcic, D., Müsgen, P., Pätz, H.-W., Holland, F., Hofzumahaus, A., Schäfer, H.-J., Schröder, S., and Volz-Thomas, A.: Hydrocarbon measurements at Pabstthum during the BERLIOZ campaign and modelling of free radicals, J. Geophys. Res., 108, DOI:10.1029/2001JD000866, 2003. Kurtenbach, R., Becker, K. H., Gomes, J. A. G., Kleffmann, J., Lorzer, J. C., Spittler, M., Wiesen, P., Ackermann, R., Geyer, A., and Platt, U.: Investigations of emissions and heterogeneous formation of HONO in a road traffic tunnel, Atmos. Env., 35, 3385–3394, 2001. Lee, J. L., Lewis, A. C., Monks P. S., et al.: Ozone photochemistry during the UK heatwave of August 2003, Atmos. Env., 40, 7598–7613, 2006. Lewis, A. C., Carslaw, N., Marriott, P. J., Kinghorn, R. M., Morrison, P., Lee, A. L., Bartle, K. D., and Pilling, M. J.: A larger pool of ozone-forming carbon compounds in urban atmospheres, Nature, 405, 778–781, 2000. Martinez, M., Harder, H., Kovacs, T. A., et al.: OH and HO₂ concentrations, sources, and loss rates during the Southern Oxidants Study in Nashville, Tennessee, summer 1999, J. Geophys. Res., 108, doi:10.1029/2003JD003551, 2003. Mihelcic, D., Holland, F., Hofzumahaus, A., Hoppe, L., Konrad, S., Müsgen, P., Pätz, H.-W., Schäfer, H.-J., Schmitz, T., Volz-Thomas, A., Bächmann, Schlomski, S., Platt, U., Geyer, A., Alicke, B., and Moortgat, G. K.: Peroxy radicals during BERLIOZ at Pabstthum: Measurements, radical budgets and ozone production, J. Geophys. Res., 108, doi:10.1029/2001JD001014, 2003. Monks, P. S.: Gas-phase radical chemistry in the troposphere, Chem. Soc. Rev., 34, 376–395, 2005. Monks, P. S., Rickard, A. R., Hall, A. L., and Richards, N. A. D.: Attenuation of spectral actinic flux and photolysis frequencies at the surface through homogeneous cloud fields, J. Geophys. Res., 109, 17 206, 2004. Morita, A., Kanaya, Y., and Francisco, J. S.: Uptake of the HO₂ radical by water: Molecular dynamics calculations and their implications for atmospheric modelling, J. Geophys. Res., 109, Art. No. D09201, 2004. Paulson, S. E., Chung, M., Sen, A. D., and Orzechowska, G.: Measurement of OH radical formation from the reaction of ozone with several biogenic alkenes, J. Geophys. Res. 103, 25 533–25 539, 1998. Ren, X., Brune, W. H., Mao, J., Mitchell, M. J., Lesher, R. L., Simpas, J. B., Metcalf, A. R., Schwab, J. J., Li, Y., Demerjian, K. L., Felton, H. D., Boynton, G., Adams, A., Perry, J., He, Y., Zhou, X., and Hou, J.: Behaviour of OH and HO₂ in the winter atmosphere in New York City, Atmos. Env. 40, supplement 2, 252–263, 2006. Ren, X., Brune, W. H., Cantrell, C. A., Edwards, G. D., Shirley, T., Metcalf, A. R., and Lesher, R. L.: Hydroxyl and peroxy radical chemistry in a rural area of central Pennsylvania: Observations and model comparisons, J. Atmos. Chem., 52, 231–257, 2005. Ren, X., Harder, H., Martinez, M., Lesher, R. L., Oliger, A., Simpas, J. B., Brune, W. H., Schwab, J. J., Demerjian, K. L., He, Y., Zhou, X., and Gao, H.: OH and HO₂ chemistry in the urban atmosphere of New York City, Atmos. Env., 37, 3639–-3651, 2003. Salisbury, G., Rickard, A. R., Monks, P. S., Allan, B. J., Baugitte, S., Penkett, S. A., Carslaw, N., Lewis, A. C., Creasey, D. J., Heard, D. E., Jaobs, P. J., and Lee, J. D.: Production of peroxy radicals at night via reactions of ozone and the nitrate radical in the marine boundary layer, J. Geophys. Res., 106, 12 669–12 687, 2001. Saunders, S. M., Jenkin, M. E., Derwent, R. G., and Pilling, M. J.: Protocol for the development of the Master Chemical Mechanism, MCM v3 (Part A): Tropospheric degradation of non-aromatic volatile organic compounds, Atmos. Chem. Phys., 3, 161–180, 2003. Saylor, R. D.: An estimate of the potential significance of heterogenous loss to aerosols as an additional sink for hydroperoxy radicals in the troposphere, Atmos. Environ., 31, 3653–3658, 1997. Shirley, T. R., Brune, W. H., Ren, X., Mao, J., Lesher, R., Cardenas, B., Volkamer, R., Molina, L. T., Molina, M. J., Lamb, B., Velasco, E., Jobson, T., and Alexander, M.: Atmospheric oxidation in the Mexico City metropolitan area (MCMA) during April 2003, Atmos. Chem. Phys. Discuss., 5, 6041–6076, 2005. Sillman, S.: The relation between ozone, NO$_x$ and hydrocarbons in urban and polluted rural environments, Atmos. Env., 33, 1821–1845. 1999. Smith, S. C., Lee, J. D., Bloss, W. J., Johnson, G. P., and Heard, D. E.: Concentration of OH and HO₂ during NAMBLEX: Measurements and Steady State analysis, Atmos. Chem. Phys., 5, 12 403–12 464, 2005. Sommariva, R., Bloss, W. J., Brough, N., Carslaw, N., Flynn, M., Haggerstone, A.-L. Heard, D. E., Hopkins, J. R., Lee, J. D., Lewis, A. C., McFiggins, G., Monks, P.S Penkett, S.A., Pilling, M.J., Plane, J.M.C., Read, K.A., Saiz-Lopez, A., Rickard A. R., and Williams P. I: OH and HO₂ chemistry during NAMBLEX: roles of oxygenates, halogen oxides and heterogeneous uptake, Atmos. Chem. Phys.,, 6, 1135–1153, 2006. Sommariva, R., Haggerstone, A.-L., Carpenter, L. J., Carslaw, N., Creasey, D. J., Heard, D. E., Lee, J. D., Lewis, A. C., Pilling, M. J., and Zádor, J.: OH and HO₂ chemistry in clean marine air during SOAPEX-2, Atmos. Chem. Phys., 4, 839–856, 2004. Stedman, J. R.: The predicted number of air pollution related deaths in the UK during the August 2003 heatwave, Atmos. Env., 38, 1087–1090, 2004. Stevens, P. S., Mather, J. H., Brune, W. H., Eisele, F., Tanner, D., Jefferson, A., Cantrell, C., Shetter, R., Sewall, S., Fried, A., Henry, B., Williams, E., Baumann, K., Glodan, P., and Kuster, W.: HO₂/OH and RO₂/HO₂ ratios during the Tropospheric OH Photochemistry Experiment: Measurement and theory, J. Geophys. Res., 102, 6379–6391, 1997. Stockwell, W. R., Kirchner, F., and Kuhn, M.: A new mechanism for regional atmospheric chemistry modelling, J. Geophys. Res., 102, 25 847–25 879, 1997. Tan, D., Faloona, I., Simpas, J. B., Brune, W., Shepson, P. B., Couch, T. L., Sumner, A. L., Carroll, M. A., Thornberry, T., Apel, E., Riemer, D., and Stockwell, W.: HOx budgets in a deciduous forest: results from the prophet summer campaign. J. Geophys. Res., 106, 24 407–24 427, 2001. Thornton, J. and Abbat, J. P. D.: Measurements of HO₂ uptake to aqueous aerosol: Mass accommodation coefficients and net reactive loss, J. Geophys. Res., 110, Art. No. D08309, 2005. Thornton, J. A., Wooldridge, P. J., Cohen, R. C., Martinez, M., Harder H., Brune, W. H., Williams, E. J., Roberts, J. M., Fehsenfeld, F. C., Hall, S. R., Shetter, R. E., Wert, B. P., and Fried, A.: Ozone production rates as a function of NOx abundances and HOx production rates in the Nashville urban plume, JGR, 107, NO. D12, 4146, 10.1029/2001JD000932, 2002. Volz-Thomas, A., Pätz, H.-W., Houben, N., Konrad, S., Mihelcic, D., Klupfel, T., and Perner, D.: Inorganic trace gases and peroxy radicals during BERLIOZ at Pabstthum: An investigation of the photostationary state of NO_x and O₃, J. Geophys. Res., 108, doi:10.1029/2001JD001255, 2003 .