Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 8 4 2008 10.5194/acpd-8-15739-2008 http://www.atmos-chem-phys-discuss.net/8/15739/2008/ http://www.atmos-chem-phys-discuss.net/8/15739/2008/acpd-8-15739-2008.html http://www.atmos-chem-phys-discuss.net/8/15739/2008/acpd-8-15739-2008.pdf 15739 15789 2008-08-19 Ozone production, nitrogen oxides, and radical budgets in Mexico City: observations from Pico de Tres Padres E. C. Wood ezrawood@aerodyne.com S. C. Herndon T. B. Onasch J. H. Kroll M. R. Canagaratna C. E. Kolb D. R. Worsnop J. A. Neuman R. Seila M. Zavala W. B. Knighton Aerodyne Research, Inc., Billerica, Massachusetts, USA Earth System Research Laboratory, NOAA, Boulder, Colorado, USA National Exposure Research Laboratory, Environmental Protection Agency, Research Triangle Park, North Carolina, USA Molina Center for Energy and the Environment, La Jolla, California, USA Dept. of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, USA Observations at a mountain-top site within the Mexico City basin are used to characterize ozone production and destruction, the nitrogen oxide budget, and the radical budget during the MILAGRO campaign. An ozone production rate of ~50 ppbv/h was observed in a stagnant air mass during the afternoon of 12 March 2006, which is among the highest observed anywhere in the world. Approximately half of the ozone destruction was due to the oxidation of NO₂. During this time period ozone production was VOC-limited, deduced by a comparison of the radical production rates and the formation rate of NO_x oxidation products (NO_z) For [NO_x]/[NO_y] values between 0.2 and 0.8, gas-phase HNO₃ typically accounted for less than 10% of NO_z and accumulation-mode particulate nitrate (NO₃^−_(PM)) accounted for 20%–70% of NO_z, consistent with high ambient NH₃ concentrations. The fraction of NO_z accounted for by the sum of HNO_3(g) and NO₃^−_(PM) decreased with photochemical processing. This decrease is apparent even when dry deposition of HNO₃ is accounted for, and indicates that HNO₃ formation decreased relative to other NO_x "sink" processes during the first 12 h of photochemistry and/or a significant fraction of the nitrate was associated with the coarse aerosol size mode. The ozone production efficiency of NO_x on 11 and 12 March 2006 was approximately 7 on a time scale of one day. A new metric for ozone production efficiency that relates the dilution-adjusted ozone mixing ratio to cumulative OH exposure is proposed. Bassett, M. E.: Atmospheric Equilibrium-Model of Sulfate and Nitrate Aerosols .2. Particle-Size Analysis, Atmos. Environ., 18, 1163–1170, 1984. Brown, S. S., Neuman, J. A., Ryerson, T. B., Trainer, M., Dubé, W. P., Holloway, J. S., Warneke, C., De Gouw, J. A., Donnelly, S. G., and Atlas, E.: Nocturnal odd-oxygen budget and its implications for ozone loss in the lower troposphere, Geophys. Res. Lett., 33, L08801, doi:10.1029/2006GL025900, 2006. Calvert, J. G., Atkinson, R., Kerr, J. A., Madronich, S., Moortgat, G. K., Wallington, T. J., and Yarwood, G.: The Mechanisms of Atmospheric Oxidation of the Alkenes, Oxford University Press, Oxford, 277–278, 2000. Canagaratna, M. R., Jayne, J. T., Jimenez, J. L., Allan, J. D., Alfarra, M. R., Zhang, Q., Onasch, T. B., Drewnick, F., Coe, H., Middlebrook, A., Delia, A., Williams, L. R., Trimborn, A. M., Northway, M. J., DeCarlo, P. F., Kolb, C. E., Davidovits, P., and Worsnop, D. R.: Chemical and microphysical characaterization of ambient aerosols with the Aerodyne Aerosol Mass Spectrometer, Mass Spectrom. Rev., 26, 185–222, doi:10.1002/mas.20115, 2007. 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.: OH and HO₂ radical chemistry in a forested region of north-western Greece, Atmos. Environ., 35, 4725–4737, 2001. Carter, W. P. L., Pierce, J. A., Luo, D., and Malkina, I. L.: Environmental chamber study of maximum incremental reactivities of volatile organic compounds, Atmos. Environ., 29, 2499–2511, 1995. Daum, P. H., Kleinman, L. I., Imre, D., Nunnermacker, L. J., Lee, Y. N., Springston, S. R., Newman, L., Weinstein-Lloyd, J., Valente, R. J., Imhoff, R. E., Tanner, R. L., and Meagher, J. F.: Analysis of O₃ formation during a stagnation episode in central Tennessee in summer 1995, J. Geophys. Res.-Atmos., 105, 9107–9119, 2000. de Foy, B., Caetano, E., Magaña, V., Zitácuaro, A., Cárdenas, B., Retama, A., Ramos, R., Molina, L. T., and Molina, M. J.: Mexico City basin wind circulation during the MCMA-2003 field campaign, Atmos. Chem. Phys., 5, 2267–2288, 2005. de Foy, B., Varela, J. R., Molina, L. T., and Molina, M. J.: Rapid ventilation of the Mexico City basin and regional fate of the urban plume, Atmos. Chem. Phys., 6, 2321–2335, 2006. de Foy, B., Fast, J. D., Paech, S. J., Phillips, D., Walters, J. T., Coulter, R. L., Martin, T. J., Pekour, M. S., Shaw, W. J., Kastendeuch, P. P., Marley, N. A., Retama, A., and Molina, L. T.: Basin-scale wind transport during the MILAGRO field campaign and comparison to climatology using cluster analysis, Atmos. Chem. Phys., 8, 1209–1224, 2008. de Foy, B., Varela, J. R., Molina, L. T., and Molina, M. J.: Rapid ventilation of the Mexico City basin and regional fate of the urban plume, Atmos. Chem. Phys., 6, 2321–2335, 2006. de Gouw, J. A., Middlebrook, A. M., Warneke, C., Goldan, P. D., Kuster, W. C., Roberts, J. M., Fehsenfeld, F. C., Worsnop, D. R., Canagaratna, M. R., Pszenny, A. A. P., Keene, W. C., Marchewka, M., Bertman, S. B., and Bates, T. S.: Budget of organic carbon in a polluted atmosphere: Results from the New England Air Quality Study in 2002, J. Geophys. Res.-Atmos., 110, D16305, doi:10.1029/2004JD005623, 2005. Derwent, R. G., Jenkin, M. E., and Saunders, S. M.: Photochemical ozone creation potentials for a large number of reactive hydrocarbons under European conditions, Atmos. Environ., 30, 181–199, 1996. Drewnick, F., Hings, S. S., DeCarlo, P., Jayne, J. T., Gonin, M., Fuhrer, K., Weimer, S., Jimenez, J. L., Demerjian, K. L., Borrman, S., and Worsnop, D. R.: A New Time-of-Flight Aerosol Mass Spectrometer (TOF-AMS) – Instrument Description and First Field Deployment, Aerosol Sci. Tech., 39, 637–658, 2005. Emmerson, K. M., Carslaw, N., Carslaw, D. C., Lee, J. D., McFiggans, G., Bloss, W. J., Gravestock, T., Heard, D. E., Hopkins, J., Ingham, T., Pilling, M. J., Smith, S. C., Jacob, M., and Monks, P. S.: Free radical modelling studies during the UK TORCH Campaign in Summer 2003, Atmos. Chem. Phys., 7, 167–181, 2007. Fast, J. D., De Foy, B., Acevedo Rosas, F., Caetano, E., Carmichael, G., Emmons, L., McKenna, D., Mena, M., Skamarock, W., Tie, X., Coulter, R. L., Barnard, J. C., Wiedinmyer, C., and Madronich, S.: A meteorological overview of the MILAGRO field campaigns, Atmos. Chem. Phys., 7, 2233–2257, 2007. Fountoukis, C., Nenes, A., Sullivan, A., Weber, R., VanReken, T., Fischer, M., Matias, E., Moya, M., Farmer, D., and Cohen, R. C.: Thermodynamic characterization of Mexico City aerosol during MILAGRO 2006, Atmos. Chem. Phys. Discuss., 7, 9203–9233, 2007. Garcia, A. R., Volkamer, R., Molina, L. T., Molina, M. J., Samuelson, J., Mellqvist, J., Galle, B., Herndon, S. C., and Kolb, C. E.: Separation of emitted and photochemical formaldehyde in Mexico City using a statistical analysis and a new pair of gas-phase tracers, Atmos. Chem. Phys., 6, 4545–4557, 2006. Geyer, A., Alicke, B., Ackermann, R., Martinez, M., Harder, H., Brune, W., Di Carlo, P., Williams, E., Jobson, T., Hall, S., Shetter, R., and Stutz, J.: Direct observations of daytime NO₃: Implications for urban boundary layer chemistry, J. Geophys. Res., 108, 4368, doi:4310.1029/2002JD002967, 2003. Hennigan, C. J., Sullivan, A. P., Fountoukis, C. I., Nenes, A., Hecobian, A., Vargas, O., Case Hanks, A. T., Huey, L. G., Lefer, B. L., Russell, A. G., and Weber, R. J.: On the volatility and production mechanims of newly formed nitrate and water soluble organic aerosol in Mexico City, Atmos. Chem. Phys. Discuss., 8, 4811–4829, 2008. Herndon, S. C., Onasch, T., Wood, E. C., Kroll, J. H., Canagaratna, M., Jayne, J., Zavala, M., Knighton, W. B., Mazzoleni, C., Dubey, M. K., Ulbrich, I., Jimenez, J. L., Seila, R., de Gouw, J. A., De Foy, B., Fast, J., Molina, L., Kolb, C. E., and Worsnop, D. R.: The correlation of secondary organic aerosol with odd oxygen in Mexico City outflow, Geophys. Res. Lett., 35, L15804, doi:10.1029/2008GL034508, 2008. Herndon, S. C., Jayne, J. T., Zahniser, M. S., Worsnop, D. R., Knighton, B., Alwine, E., Lamb, B. K., Zavala, M., Nelson, D. D., and McManus, J. B.: Characterization of urban pollutant emission fluxes and ambient concentration distributions using a mobile laboratory with rapid response instrumentation, Faraday Discuss., 130, 327–339, 2005. Herndon, S. C., Zahniser, M. S., Nelson Jr., D. D., Shorter, J., McManus, J. B., Jiménez, R., Warneke, C., and Gouw, J. A.: Airborne measurements of HCHO and HCOOH during the New England Air Quality Study 2004 using a pulsed quantum cascade laser spectrometer, J. Geophys. Res., 112, D10S03, doi:10.1029/2006JD007600., 2007. Hodzic, A.: A model evaluation of coarse-mode nitrate heterogeneous formation on dust particles, Atmos. Environ., 40, 4158–4171, 2006. Khan, H. A.: Benzene's toxicity: a consolidated short review of human and animal studies, Human and Experimental Toxicology, 26, 677–685, 2007. Kleinman, L. I.: Ozone process insights from field experiments - part II: Observation-based analysis for ozone production, Atmos. Environ., 34, 2023–2033, 2000. Kleinman, L. I., Daum, P. H., Imre, D., Lee, Y. N., Nunnermacker, L. J., Springston, S. R., Weinstein-Lloyd, J., and Rudolph, J.: Ozone production rate and hydrocarbon reactivity in 5 urban areas: A cause of high ozone concentration in Houston, Geophys. Res. Lett., 29(10), 1467, doi:10.1029/2001GL014569, 2002. Kleinman, L. I.: The dependence of tropospheric ozone production rate on ozone precursors, Atmos. Enviro., 39, 575–586, 2005. Kleinman, L. I., Springston, S. R., Daum, P. H., Lee, Y. N., Nunnermacker, L. J., Senum, G. I., Wang, J., Weinstein-Lloyd, J., Alexander, M. L., Hubbe, J., Ortega, J., Canagaratna, M. R., and Jayne, J.: The time evolution of aerosol composition over the Mexico City plateau, Atmos. Chem. Phys., 8, 1559–1575, 2008. Kolb, C. E., Herndon, S. C., McManus, J. B., Shorter, J. H., Zahniser, M. S., Nelson, D. D., Jayne, J. T., Canagaratna, M. R., and Worsnop, D. R.: Mobile Laboratory with Rapid Response Instruments for Real-Time Measurements of Urban and Regional Trace Gas and Particulate Distributions and Emission Source Characteristics, Environ. Sci. Technol., 38, 5694–5703, 2004. Laskin, A., Wietsma, T. W., Krueger, B. J., and Grassian, V. H.: Heterogenous chemistry of individual mineral dust particles with nitric acid: A combined CCSEM/EDX, ESEM, and ICP-MS study, J. Geophys. Res.-Atmos., 110(D10), 10208, doi:10.1029/2004JD005206, 2005. Lei, W., de Foy, B., Zavala, M., Volkamer, R., and Molina, L. T.: Characterizing ozone production in the Mexico City Metropolitan Area: a case study using a chemical transport model, Atmos. Chem. Phys., 7, 1347–1366, 2007. Lelieveld, J., Butler, T. M., Crowley, J. N., Dillon, T. J., Fischer, H., Ganzeveld, L., Harder, H., Lawrence, M. G., Martinez, M., Taraborrelli, D., and Williams, J.: Atmospheric oxidation capacity sustained by a tropical forest, Nature, 452, 737–740, 2008. Li, S., Matthews, J., and Sinha, A.: Atmospheric Hydroxyl Radical Production from Electronically Excited NO₂ and H₂O, Science, 319, 1657–1660, 2008. Liang, J., and Jacobson, M. Z.: Effects of subgrid segregation on ozone production efficiency in a chemical model, Atmos. Environ., 34, 2975–2982, 2000. Lim, Y. B.: Products and mechanism of secondary organic aerosol formation from reactions of n-alkanes with OH radicals in the presence of NO_x, Environ. Sci. Technol., 39, 9229–9236, 2005. Lin, X., Trainer, M., and Liu, S. C.: On the Nonlinearity of the Tropospheric Ozone Production, J. Geophys. Res., 93, 15 879–15 888, 1988. Liu, P. S. K., Deng, R., Smith, K. A., Williams, L. R., Jayne, J. T., Canagaratna, M. R., Moore, K., Onasch, T. B., Worsnop, D. R., and Deshler, T.: Transmission Efficiency of an Aerodynamic Focusing Lens System: Comparison of Model Calculations and Laboratory Measurements for the Aerodyne Aerosol Mass Spectrometer, Aerosol Sci. Technol., 41, 721–733, 2007. Madronich, S.: Chemical Evolution of gaseous air pollutants down-wind of tropical megacities: Mexico City case study, Atmos. Environ., 40, 6012–6018, 2006. McCreanor, J., Cullinan, P., Nieuwenhuijsen, M. J., Stewart-Evans, J., Malliarou, E., Jarup, L., Harrington, R., Svartengren, M., Han, I., Ohman-Strickland, P., Chung, K. F., and Zhang, J.: Respiratory Effects of Exposure to Diesel Traffic in Persons with Asthma, The New England Journal of Medicine, 357, 2348–2358, 2007. Moffet, R. C., De Foy, B., Molina, L. T., Molina, M. J., and Prather, A.: Measurement of ambient aerosols in northern Mexico City by single particle mass spectrometry, Atmos. Chem. Phys. Discuss., 7, 6413–6457, 2007. Molina, L. T., Molina, M. J., Slott, R. S., Kolb, C. E., Gbor, P. K., Meng, F., Singh, R. B., Galvez, O., Sloan, J. J., Anderson, W. P., Tang, X., Hu, M., Xie, S., Shao, M., Zhu, T., Zhang, Y. H., Gurjar, B. R., Artaxo, P. E., Oyola, P., Gramsch, E., Hidalgo, D., and Gertler, A. W.: Air Quality in Selected Megacities, Journal of the Air and Waste Management Association, 55, 1–73, 2004. Nelson, D., McManus, J., Urbanski, S., Herndon, S., and Zahniser, M.: High precision measurements of atmospheric nitrous oxide and methane using thermoelectrically cooled mid-infrared quantum cascade lasers and detectors, Spectrochimica Acta part a-Molecular and Biomolecular Spectroscopy, 60, 3325–3335, 2004. Nunnermacker, L. J., Imre, D., Daum, P. H., Kleinman, L., Lee, Y. N., Springston, S. R., Newman, L., Weinstein-Lloyd, J., Luke, W. T., Banta, R., Alvarez, R., Senff, C., Sillman, S., Holdren, M., Keigley, G. W., and Zhou, X.: Characterization of the Nashville urban plume on 3 July and 18 July, 1995, J. Geophys. Res., 103, 28 129–28 148, 1998. Nunnermacker, L. J., Kleinman, L. I., Imre, D., Daum, P. H., Lee, Y. N., Lee, J. H., Springston, S. R., Newman, L., and Gillani, N.: NO_y lifetimes and O₃ production efficiencies in urban and power plant plumes: Analysis of field data, J. Geophys. Res.-Atmos., 105, 9165–9176, 2000. Nunnermacker, L. J., Weinstein-Lloyd, J. B., Hillery, B., Giebel, B., Kleinman, L. I., Springston, S. R., Daum, P. H., Gaffney, J., Marley, N., and Huey, G.: Aircraft and ground-based measurements of hydroperoxides during the 2006 MILAGRO field campaign, Atmos. Chem. Phys. Discuss., 8, 8951–8995, 2008. Roberts, J. M., Fehsenfeld, F. C., Liu, S. C., Bollinger, M. J., Hahn, C., Albritton, D. L., and Sievers, R. E.: Measurements of aromatic hydrocarbon ratios and NOx concentrations in the rural troposphere: Estimates of air mass photochemical age and NO_x removal rate, Atmos. Environ., 18, 2421–2432, 1984. Rogers, T. M., Grimsrud, E. P., Herndon, S. C., Jayne, J. T., Kolb, C. E., Allwine, E., Westberg, H., Lamb, B. K., Zavala, M., Molina, L. T., Molina, M. J., and Knighton, W. B.: On-road measurements of volatile organic compounds in the Mexico City metropolitan area using proton transfer reaction mass spectrometry, Int. J. Mass Spectrom., 252, 26–37, 2006. Ryerson, T. B., Trainer, M., Holloway, J. S., Parrish, D. D., Huey, L. G., Sueper, D. T., Frost, G. J., Donnelly, S. G., Schauffler, S., Atlas, E. L., Kuster, W. C., Goldan, P. D., Hubler, G., Meagher, J. F., and Fehsenfeld, F. C.: Observations of ozone formation in power plant plumes and implications for ozone control strategies, Science, 292, 719–723, 2001. San Martini, F. M., Dunlea, E. J., Grutter, M., Onasch, T. B., Jayne, J. T., Canagaratna, M. R., Worsnop, D. R., Kolb, C. E., Shorter, J. H., Herndon, S. C., Zahniser, M. S., Ortega, J. M., McRae, G. J., Molina, L. T., and Molina, M. J.: Implementation of a Markov Chain Monte Carlo method to inorganic aerosol modeling of observations from the MCMA-2003 campaign – Part I: Model description and application to the La Merced site, Atmos. Chem. Phys., 6, 4867–4888, 2006. Sander, S. P., Friedl, R. R., Golden, D. M., Kurylo, M. J., Moortgat, G. K., Wine, P. H., Ravishankara, A. R., Kolb, C. E., Molina, M. J., Finlayson-Pitts, B. J., Huie, R. E., and Orkin, V. L.: Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies: Evaluation Number 15, Jet Propulsion Laboratory, JPL Publication 06-2, 2006. 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. Seila, R. L., Main, H. H., Arriaga, J. L., Martinez, G., and Ramadan, A. B.: Atmospheric volatile organic compound measurements during the 1996 Paso del Norte Study, The Science of the Total Environment, 276, 153–169, 2001. Shaw, W. J., Pekour, M. S., Coulter, R. L., Martin, T. J., and Walters, J. T.: The daytime mixing layer observed by radiosonde, profiler and lidar during MILAGRO, Atmos. Chem. Phys. Discuss., 7, 15 025–15 065, 2007. 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., 6, 2753–2765, 2006. Shon, Z. H., Madronich, S., Song, S. K., Flocke, F. M., Knapp, D. J., Anderson, R. S., Shetter, R. E., Cantrell, C. A., and Hall, S. R.: Characteristics of the NO-NO₂-O₃ system in different chemical regimes during the MIRAGE-Mex field campaign, Atmos. Chem. Phys. Discuss., 8, 2275- -2309, 2008. Shorter, J. H., Herndon, S., Zahniser, M. S., Nelson, D. D., Wormhoudt, J., Demerjian, K. L., and Kolb, C. E.: Real-time Measurements of Nitrogen Oxide Emissions from In-use New York City Transit Buses using a Chase Vehicle, Environ. Sci. Technol, 39, 7991–8000, 2005. Stull, R. B.: An Introduction to Boundary Layer Meteorology, Kluwer Academic Publishers, The Netherlands, 1988. 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 NO_x abundances and HO_x production rates in the Nashville urban plume, J. Geophys. Res.-Atmos., 107, 4146, 2002. Thornton, J. A., Jaegle, L., and McNeill, V. F.: Assessing known pathways for HO₂ loss in aqueous atmospheric aerosols: Regional and global impacts on tropospheric oxidants, J. Geophys. Res., 113, D05303, doi:10.1029/2007JD009236, 2008. Tie, X., Madronich, S., Li, G., Ying, Z., Zhang, R., Garcia, A. R., Lee-Taylor, J., and Liu, Y.: Characterizations of chemical oxidants in Mexico City: A regional chemical dynamical model (WRF-Chem) study, Atmos. Environ., 41, 1989–2008, 2007. Tressol, M., Ordonez, C., Zbinden, R., Brioude, J., Thouret, V., Mari, C., Nedelec, P., Cammas, J. P., Smit, H., Patz, H. W., and Volz-Thomas, A.: Air pollution during the 2003 European heat wave as seen by MOZAIC airliners, Atmos. Chem. Phys., 8, 2133–2150, 2008. UN: World Urbanization Prospects: The 2007 Revision, United Nations, New York, p. 10, L17811, doi:10.10029/2005GL022616 2008. Velasco, E., Lamb, B., Westberg, H., Allwine, E., Sosa, G., Arriaga-Colina, J. L., Jobson, B. T., Alexander, M. L., Prazeller, P., Knighton, W. B., Rogers, T. M., Grutter, M., Herndon, S. C., Kolb, C. E., Zavala, M., De Foy, B., Volkamer, R., Molina, L. T., and Molina, M. J.: Distribution, magnitudes, reactivities, ratios and diurnal patterns of volatile organic compounds in the Valley of Mexico during the MCMA 2002 and 2003 field campaigns, Atmos. Chem. Phys., 7, 329–353, 2007. Volkamer, R., Molina, L. T., Molina, M. J., Shirley, T., and Brune, W. H.: DOAS measurement of glyoxal as an indicator for fast VOC chemistry in urban air, Geophys. Res. Lett., 32, 2005. Volkamer, R., Jimenez, J. L., San Martini, F., Dzepina, K., Zhang, Q., Salcedo, D., Molina, L. T., Worsnop, D. R., and Molina, M. J.: Secondary organic aerosol formation from anthropogenic air pollution: Rapid and higher than expected, Geophys. Res. Lett., 33, L17811, doi:101029/2006GL026899, 2006. Volkamer, R., Sheehy, P., Molina, L., and Molina, M.: Oxidative capacity of the Mexico City atmosphere – Part 1: A radical source perspective, Atmos. Chem. Phys. Discuss., 7, 5365–5412, 2007. Wang, Y. H., Logan, J. A., and Jacob, D. J.: Global simulation of tropospheric O₃-NO_x-hydrocarbon chemistry 2. Model evaluation and global ozone budget, J. Geophys. Res.-Atmos., 103, 10 727–10 755, 1998. Wesely, M. L. and Hicks, B. B.: A review of the current status of knowledge on dry deposition, Atmos. Environ., 34, 2261–2282, 2000. Williams, E. J., Baumann, K., Roberts, J. M., Bertman, S. B., Norton, R. B., Fehsenfeld, F. C., Springston, S. R., Nunnermacker, L. J., Newman, L., Olszyna, K., Meagher, J., Hartsell, B., Edgerton, E., Pearson, J. R., and Rodgers, M. O.: Intercomparison of ground-based NO_y measurement techniques, J. Geophys. Res.-Atmos., 103, 22 261–22 280, 1998. Yauk, C., Polyzos, A., Rowan-Carroll, A., Somers, C. M., Godschalk, R. W., Van Schooten, F. J., Berndt, M. L., Pogribny, I. P., Koturbash, I., Williams, A., Douglas, G. R., and Kovalchuk, O.: Germ-line mutations, DNA damage, and global hypermethylation in mice exposed to particulate air pollution in an urban/industrial location, P. Natl. Acad. Sci., 105, 605–610, 2008. Zavala, M., Herndon, S. C., Slott, R. S., Dunlea, E. J., Marr, L. C., Shorter, J. H., Zahniser, M., Knighton, W. B., Rogers, T. M., and Kolb, C. E.: Characterization of on-road vehicle emissions in the Mexico City Metropolitan Area using a mobile laboratory in chase and fleet average measurement modes during the MCMA-2003 field campaign, Atmos. Chem. Phys., 6, 5129–5142, 2006. Zheng, J., Zhang, R., Fortner, E. C., Molina, L., Aiken, A. C., Jimenez, J. L., Gaggeler, K., Dommen, J., Dusanter, S., Stevens, P. S., and Tie, X.: Measurements of HNO₃ and N₂O$_5$ using Ion drift – Chemical Ionization Mass Spectrometry during the MCMA - 2006 Campaign, Atmos. Chem. Phys. Discuss., 8, 4877–4909, 2008.