References

ACP

Atmospheric Chemistry and Physics

ACP

1680-7324

Copernicus GmbH

Göttingen, Germany

10.5194/acp-13-1057-2013

Missing OH source in a suburban environment near Beijing: observed and modelled OH and HO2 concentrations in summer 2006

K. D.

¹ ² Hofzumahaus

² Holland

² Bohn

² Brauers

² Fuchs

² Hu

¹ Häseler

² Kita

³ Kondo

⁴ Li

¹ ² Lou

S. R.

² ⁵ ⁶ Oebel

² ⁷ Shao

¹ Zeng

L. M.

¹ Wahner

² Zhu

¹ Zhang

Y. H.

¹ Rohrer

State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, China

Institut für Energie und Klimaforschung: Troposphäre, Forschungszentrum Jülich, Jülich, Germany

Faculty of Science, Ibaraki University, Ibaraki, Japan

University of Tokyo, Research Center for Advanced Science and Technology, Tokyo, Japan

School of Environmental Science and Technology, Shanghai Jiao Tong University, Shanghai, China

now at: Shanghai Academy Of Environmental Sciences, Shanghai, China

now at: Carl Zeiss SMS GmbH, Jena, Germany

25 01 2013

13 2 1057 1080

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/13/1057/2013/acp-13-1057-2013.html

The full text article is available as a PDF file from http://www.atmos-chem-phys.net/13/1057/2013/acp-13-1057-2013.pdf

Measurements of ambient OH and HO2 radicals were performed by laser induced fluorescence (LIF) during CAREBeijing2006 (Campaigns of Air Quality Research in Beijing and Surrounding Region 2006) at the suburban site Yufa in the south of Beijing in summer 2006. On most days, local air chemistry was influenced by aged air pollution that was advected by a slow, almost stagnant wind from southern regions. Observed daily concentration maxima were in the range of (4–17) × 106 cm−3 for OH and (2–24) × 108 cm−3 for HO2 (including an estimated interference of 25% from RO2). During daytime, OH reactivities were generally high (10–30 s−1) and mainly contributed by observed VOCs and their calculated oxidation products. The comparison of modelled and measured HOx concentrations reveals a systematic underprediction of OH as a function of NO. A large discrepancy of a factor 2.6 is found at the lowest NO concentration encountered (0.1 ppb), whereas the discrepancy becomes insignificant above 1 ppb NO. This study extends similar observations from the Pearl-River Delta (PRD) in South China to a more urban environment. The OH discrepancy at Yufa can be resolved, if NO-independent additional OH recycling is assumed in the model. The postulated Leuven Isoprene Mechanism (LIM) has the potential to explain the gap between modelled and measured OH at Beijing taking into account conservative error estimates, but lacks experimental confirmation. This and the hereby unresolved discrepancy at PRD suggest that other VOCs besides isoprene might be involved in the required, additional OH recycling. Fast primary production of ROx radicals up to 7 ppb h−1 was determined at Beijing which was dominated by the photolysis of O3, HONO, HCHO, and dicarbonyls. For a special case, 20 August, when the plume of Beijing city was encountered, a missing primary HOx source (about 3 ppb h−1) was determined under high NOx conditions similar to other urban areas like Mexico City. CAREBeijing2006 emphasizes the important role of OVOCs as a radical source and sink, and the need for further investigation of the chemical degradation of VOCs in order to better understand radical chemistry in VOC-rich air.

References 1

Achtert, P., Birmili, W., Nowak, A., Wehner, B., Wiedensohler, A., Takegawa, N., Kondo, Y., Miyazaki, Y., Hu, M., and Zhu, T.: Hygroscopic growth of tropospheric particle number size distributions over the North China Plain, J. Geophys. Res., 114, D00G07, http://dx.doi.org/10.1029/2008JD010921doi:10.1029/2008JD010921, 2009.

Alicke, B., Platt, U., and Stutz, J.: Impact of nitrous acid photolysis on the total hydroxyl radical budget during the Limitation of Oxidant Production/Pianura Padana Produzione di Ozono study in Milan, J. Geophys. Res., 107, 8196, http://dx.doi.org/10.1029/2000JD000075doi:10.1029/2000JD000075, 2002.

Amedro, D., Parker, A E., Schoemaecker, C., and Fittschen, C.: Direct observation of OH radicals after 565 nm multi-photon excitation of NO2 in the presence of H2O, Chem. Phys. Lett., 513, 12–16, http://dx.doi.org/10.1016/j.cplett.2011.07.062doi:10.1016/j.cplett.2011.07.062, 2011.

Berresheim, H., Plass-Dülmer, C., Elste, T., Mihalopoulos, N., and Rohrer, F.: OH in the coastal boundary layer of Crete during MINOS: Measurements and relationship with ozone photolysis, Atmos. Chem. Phys., 3, 639–649, http://dx.doi.org/10.5194/acp-3-639-2003doi:10.5194/acp-3-639-2003, 2003.

Birdsall, A W. and Elrod, M J.: Comprehensive NO-Dependent Study of the Products of the Oxidation of Atmospherically Relevant Aromatic Compounds, J. Phys. Chem., 115, 5397–5407, 2011.

Bloss, C., Wagner, V., Jenkin, M. E., Volkamer, R., Bloss, W. J., Lee, J. D., Heard, D. E., Wirtz, K., Martin-Reviejo, M., Rea, G., Wenger, J. C., and Pilling, M. J.: Development of a detailed chemical mechanism (MCMv3.1) for the atmospheric oxidation of aromatic hydrocarbons, Atmos. Chem. Phys., 5, 641–664, http://dx.doi.org/10.5194/acp-5-641-2005doi:10.5194/acp-5-641-2005, 2005.

Bohn, B., Corlett, G. K., Gillmann, M., Sanghavi, S., Stange, G., Tensing, E., Vrekoussis, M., Bloss, W. J., Clapp, L. J., Kortner, M., Dorn, H.-P., Monks, P. S., Platt, U., Plass-Dülmer, C., Mihalopoulos, N., Heard, D. E., Clemitshaw, K. C., Meixner, F. X., Prevot, A. S. H., and Schmitt, R.: Photolysis frequency measurement techniques: results of a comparison within the ACCENT project, Atmos. Chem. Phys., 8, 5373–5391, http://dx.doi.org/10.5194/acp-8-5373-2008doi:10.5194/acp-8-5373-2008, 2008.

Brauers, T., Hausmann, M., Bister, A., Kraus, A., and Dorn, H.-P.: OH radicals in the boundary layer of the Atlantic Ocean 1. Measurements by long-path absorption spectroscopy, J. Geophys. Res., 106, 7399–7414, 2001.

Butler, T M., Taraborrelli, D., Brühl, C., Fischer, H., Harder, H., Martinez, M., Williams, J., Lawrence, M G., and Lelieveld, J.: Improved simulation of isoprene oxidation chemistry with the ECHAM5/MESSy chemistry-climate model: lessons from the GABRIEL airborne field campaign, Atmos. Chem. Phys., 8, 4529–4546, http://dx.doi.org/10.5194/acp-8-4529-2008doi:10.5194/acp-8-4529-2008, 2008.

Carr, S., Heard, D E., and Blitz, M A.: Comment on "Atmospheric hydroxyl radical production from electronically excited NO2 and H2O", Science, 324, 336–336, http://dx.doi.org/10.1126/science.1166669doi:10.1126/science.1166669, 2009.

Chan, C K. and Yao, X.: Air pollution in mega cities in China, Atmos. Environ., 42, 1–42, 2008.

Chen, S., Ren, X., Mao, J., Chen, Z., Brune, W H., Lefer, B., Rappenglück, B., Flynn, J., Olson, J., and Crawford, J H.: A comparison of chemical mechanisms based on TRAMP-2006 field data, Atmos. Environ., 44, 4116–4125, 2010.

Cheng, Y F., Berghof, M., Garland, R M., Wiedensohler, A., Wehner, B., Muller, T., Su, H., Zhang, Y H., Achtert, P., Nowak, A., Poschl, U., Zhu, T., Hu, M., and Zeng, L M.: Influence of soot mixing state on aerosol light absorption and single scattering albedo during air mass aging at a polluted regional site in northeastern China, J. Geophys. Res., 114, D00G10, http://dx.doi.org/10.1029/2008JD010883doi:10.1029/2008JD010883, 2009.

Crounse, J D., Paulot, F., Kjaergaard, H G., and Wennberg, P O.: Peroxy radical isomerization in the oxidation of isoprene, Phys. Chem. Chem. Phys., 13, 13607–13613, http://dx.doi.org/10.1039/c1cp21330jdoi:10.1039/c1cp21330j, 2011.

Da~Silva, G., Graham, C., and Wang, Z F.: Unimolecular beta-Hydroxyperoxy Radical Decomposition with OH Recycling in the Photochemical Oxidation of Isoprene, Environ. Sci. Technol., 44, 250–256, http://dx.doi.org/10.1021/es900924ddoi:10.1021/es900924d, 2010.

Dillon, T J. and Crowley, J N.: Direct detection of OH formation in the reactions of HO2 with CH3C(O)O2 and other substituted peroxy radicals, Atmos. Chem. Phys., 8, 4877–4889, http://dx.doi.org/10.5194/acp-8-4877-2008doi:10.5194/acp-8-4877-2008, 2008.

Dodge, M C.: Chemical oxidant mechanisms for air quality modeling: critical review, Atmos. Environ., 34, 2103–2130, 2000.

Dunlea, E. J., Herndon, S. C., Nelson, D. D., Volkamer, R. M., San Martini, F., Sheehy, P. M., Zahniser, M. S., Shorter, J. H., Wormhoudt, J. C., Lamb, B. K., Allwine, E. J., Gaffney, J. S., Marley, N. A., Grutter, M., Marquez, C., Blanco, S., Cardenas, B., Retama, A., Ramos Villegas, C. R., Kolb, C. E., Molina, L. T., and Molina, M. J.: Evaluation of nitrogen dioxide chemiluminescence monitors in a polluted urban environment, Atmos. Chem. Phys., 7, 2691–2704, http://dx.doi.org/10.5194/acp-7-2691-2007doi:10.5194/acp-7-2691-2007, 2007.

Dusanter, S., Vimal, D., Stevens, P. S., Volkamer, R., Molina, L. T., Baker, A., Meinardi, S., Blake, D., Sheehy, P., Merten, A., Zhang, R., Zheng, J., Fortner, E. C., Junkermann, W., Dubey, M., Rahn, T., Eichinger, B., Lewandowski, P., Prueger, J., and Holder, H.: Measurements of OH and HO2 concentrations during the MCMA-2006 field campaign – Part 2: Model comparison and radical budget, Atmos. Chem. Phys., 9, 6655–6675, http://dx.doi.org/10.5194/acp-9-6655-2009doi:10.5194/acp-9-6655-2009, 2009.

Ehhalt, D H.: Photooxidation of trace gases in the troposphere, Phys. Chem. Chem. Phys., 1, 5401–5408, 1999.

Ehhalt, D H. and Rohrer, F.: Dependence of the OH concentration on solar UV, J. Geophys. Res., 105, 3565–3571, 2000.

Elshorbany, Y F., Kleffmann, J., Hofzumahaus, A., Kurtenbach, R., Wiesen, P., Brauers, T., Bohn, B., Dorn, H.-P., Fuchs, H., Holland, F., Rohrer, F., Tillmann, R., Wegener, R., Wahner, A., Kanaya, Y., Yoshino, A., Nishida, S., Kajii, Y., Martinez, M., Kubistin, D., Harder, H., Lelieveld, J., Elste, T., Plass-D\"lmer, C., Stange, G., Berresheim, H., and Schurath, U.: HO$_\mathrmx$ budgets during HOxComp: A case study of HO$_\mathrmx$ chemistry under NO$_\mathrmx$-limited conditions, J. Geophys. Res., 117, D03307, http://dx.doi.org/10.1029/2011JD017008doi:10.1029/2011JD017008, 2012.

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, 165–183, 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, http://dx.doi.org/10.5194/acp-7-167-2007doi:10.5194/acp-7-167-2007, 2007.

Feister, U. and Grewe, R.: Spectral Albedo Measurements in the Uv and Visible Region over Different Types of Surfaces, Photochem. Photobiol., 62, 736–744, 1995.

Finlayson-Pitts, B J. and Pitts Jr., J N.: Chemistry of the upper and lower atmosphere: Theory, experiments and applications, Academic Press, San Diego, 2000.

Fuchs, H., Bohn, B., Hofzumahaus, A., Holland, F., Lu, K D., Nehr, S., Rohrer, F., and Wahner, A.: Detection of HO2 by laser-induced fluorescence: calibration and interferences from RO2 radicals, Atmos. Meas. Tech., 4, 1209–1225, http://dx.doi.org/10.5194/amt-4-1209-2011doi:10.5194/amt-4-1209-2011, 2011.

Fuchs, H., Dorn, H.-P., Bachner, M., Bohn, B., Brauers, T., Gomm, S., Hofzumahaus, A., Holland, F., Nehr, S., Rohrer, F., Tillmann, R., and Wahner, A.: Comparison of OH concentration measurements by DOAS and LIF during SAPHIR chamber experiments at high OH reactivity and low NO concentration, Atmos. Meas. Tech., 5, 1611–1626, http://dx.doi.org/10.5194/amt-5-1611-2012doi:10.5194/amt-5-1611-2012, 2012.

Garland, R M., Schmid, O., Nowak, A., Achtert, P., Wiedensohler, A., Gunthe, S S., Takegawa, N., Kita, K., Kondo, Y., Hu, M., Shao, M., Zeng, L M., Zhu, T., Andreae, M O., and Pöschl, U.: Aerosol optical properties observed during Campaign of Air Quality Research in Beijing 2006 (CAREBeijing-2006): Characteristic differences between the inflow and outflow of Beijing city air, J. Geophys. Res., 114, D00G04, http://dx.doi.org/10.1029/2008JD010780doi:10.1029/2008JD010780, 2009.

Geiger, H., Barnes, I., Bejan, I., Benter, T., and Spittler, M.: The tropospheric degradation of isoprene: an updated module for the regional atmospheric chemistry mechanism, Atmos. Environ., 37, 1503–1519, 2003.

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, 11643–11655, 1999.

Gong, J. C., Zhu, T., Hu, M., Zhang, L. W., Cheng, H., Zhang, L., Tong, J., and Zhang, J.: Ambient concentrations of aldehydes in relation to Beijing Olympic air pollution control measures, Atmos. Chem. Phys. Discuss., 10, 19737–-19761, http://dx.doi.org/10.5194/acpd-10-19737-2010doi:10.5194/acpd-10-19737-2010, 2010.

Gunthe, S. S., Rose, D., Su, H., Garland, R. M., Achtert, P., Nowak, A., Wiedensohler, A., Kuwata, M., Takegawa, N., Kondo, Y., Hu, M., Shao, M., Zhu, T., Andreae, M. O., and Pöschl, U.: Cloud condensation nuclei (CCN) from fresh and aged air pollution in the megacity region of Beijing, Atmos. Chem. Phys., 11, 11023–11039, http://dx.doi.org/10.5194/acp-11-11023-2011doi:10.5194/acp-11-11023-2011, 2011.

Hallquist, M., Wenger, J. C., Baltensperger, U., Rudich, Y., Simpson, D., Claeys, M., Dommen, J., Donahue, N. M., George, C., Goldstein, A. H., Hamilton, J. F., Herrmann, H., Hoffmann, T., Iinuma, Y., Jang, M., Jenkin, M. E., Jimenez, J. L., Kiendler-Scharr, A., Maenhaut, W., McFiggans, G., Mentel, Th. F., Monod, A., Prévôt, A. S. H., Seinfeld, J. H., Surratt, J. D., Szmigielski, R., and Wildt, J.: The formation, properties and impact of secondary organic aerosol: current and emerging issues, Atmos. Chem. Phys., 9, 5155–5236, http://dx.doi.org/10.5194/acp-9-5155-2009doi:10.5194/acp-9-5155-2009, 2009.

Heland, J., Kleffmann, J., Kurtenbach, R., and Wiesen, P.: A new instrument to measure gaseous nitrous acid (HONO) in the atmosphere, Environ. Sci. Techol., 35, 3207–3212, http://dx.doi.org/10.1021/es000303tdoi:10.1021/es000303t, 2001.

Hofzumahaus, A., Rohrer, F., Lu, K., Bohn, B., Brauers, T., Chang, C C., Fuchs, H., Holland, F., Kita, K., Kondo, Y., Li, X., Lou, S., Shao, M., Zeng, L., Wahner, A., and Zhang, Y.: Amplified Trace Gas Removal in the Troposphere, Science, 324, 1702–1704, 2009.

Holland, F., Hofzumahaus, A., Schäfer, J., Kraus, A., and Pätz, H.-W.: Measurements of OH and HO2 radical concentrations and photolysis frequencies during BERLIOZ, J. Geophys. Res., 108, 8246, http://dx.doi.org/10.1029/2001JD001393doi:10.1029/2001JD001393, 2003.

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, http://dx.doi.org/10.5194/acp-3-181-2003doi:10.5194/acp-3-181-2003, 2003.

Jenkin, M E., Hurley, M D., and Wallington, T J.: Investigation of the radical product channel of the CH3C(O)O2+HO2 reaction in the gas phase, Phys. Chem. Chem. Phys., 9, 3149–3162, 2007.

Jenkin, M E., Hurley, M D., and Wallington, T J.: Investigation of the radical product channel of the CH3OCH2O2 + HO2 reaction in the gas phase, J. Phys. Chem. A, 114, 408–416, 2010.

Jimenez, J L., Canagaratna, M R., Donahue, N M., Prevot, A. S H., Zhang, Q., Kroll, J H., DeCarlo, P F., Allan, J D., Coe, H., Ng, N L., Aiken, A C., Docherty, K S., Ulbrich, I M., Grieshop, A P., Robinson, A L., Duplissy, J., Smith, J D., Wilson, K R., Lanz, V A., Hueglin, C., Sun, Y L., Tian, J., Laaksonen, A., Raatikainen, T., Rautiainen, J., Vaattovaara, P., Ehn, M., Kulmala, M., Tomlinson, J M., Collins, D R., Cubison, M J., Dunlea, E J., Huffman, J A., Onasch, T B., Alfarra, M R., Williams, P I., Bower, K., Kondo, Y., Schneider, J., Drewnick, F., Borrmann, S., Weimer, S., Demerjian, K., Salcedo, D., Cottrell, L., Griffin, R., Takami, A., Miyoshi, T., Hatakeyama, S., Shimono, A., Sun, J Y., Zhang, Y M., Dzepina, K., Kimmel, J R., Sueper, D., Jayne, J T., Herndon, S C., Trimborn, A M., Williams, L R., Wood, E C., Middlebrook, A M., Kolb, C E., Baltensperger, U., and Worsnop, D R.: Evolution of Organic Aerosols in the Atmosphere, Science, 326, 1525–1529, 2009.

Kanaya, Y., Cao, R Q., Akimoto, H., Fukuda, M., Komazaki, Y., Yokouchi, Y., Koike, M., Tanimoto, H., Takegawa, N., and Kondo, Y.: Urban photochemistry in central Tokyo: 1. Observed and modeled OH and HO2 radical concentrations during the winter and summer of 2004, J. Geophys. Res., 112, D21312, http://dx.doi.org/10.1029/2007JD008670doi:10.1029/2007JD008670, 2007.

Kanaya, Y., Hofzumahaus, A., Dorn, H.-P., Brauers, T., Fuchs, H., Holland, F., Rohrer, F., Bohn, B., Tillmann, R., Wegener, R., Wahner, A., Kajii, Y., Miyamoto, K., Nishida, S., Watanabe, K., Yoshino, A., Kubistin, D., Martinez, M., Rudolf, M., Harder, H., Berresheim, H., Elste, T., Plass-Dülmer, C., Stange, G., Kleffmann, J., Elshorbany, Y., and Schurath, U.: Comparisons of observed and modeled OH and HO2 concentrations during the ambient measurement period of the HO$_\mathrmx$Comp field campaign, Atmos. Chem. Phys., 12, 2567–2585, http://dx.doi.org/10.5194/acp-12-2567-2012doi:10.5194/acp-12-2567-2012, 2012.

Karl, M., Dorn, H.-P., Holland, F., Koppmann, R., Poppe, D., Rupp, L., Schaub, A., and Wahner, A.: Product study of the reaction of OH radicals with isoprene in the atmosphere simulation chamber SAPHIR, J. Atmos. Chem., 55, 167–187, 2006.

Kleffmann, J., Lörzer, J., Wiesen, P., Kern, C., Trick, S., Volkamer, R., Rodenas, M., and Wirtz, K.: Intercomparison of the DOAS and LOPAP techniques for the detection of nitrous acid (HONO), Atmos. Environ., 40, 3640–3652, 2006.

Lawrence, M G., Jöckel, P., and von Kuhlmann, R.: What does the global mean OH concentration tell us?, Atmos. Chem. Phys., 1, 37–49, http://dx.doi.org/10.5194/acp-1-37-2001doi:10.5194/acp-1-37-2001, 2001.

Lelieveld, J., Butler, T M., Crowley, J N., Dillon, T J., Fischer, H., Ganzeveld, L., Harder, H., Lawrence, M G., Martinez, M., Taraborelli, D., and Williams, J.: Atmospheric oxidation capacity sustained by a tropical forest, Nature, 452, 737–740, 2008.

Li, S P., Matthews, J., and Sinha, A.: Atmospheric hydroxyl radical production from electronically excited NO2 and H2O, Science, 319, 1657–1660, 2008.

Li, X., Brauers, T., Häseler, R., Bohn, B., Fuchs, H., Hofzumahaus, A., Holland, F., Lou, S., Lu, K D., Rohrer, F., Hu, M., Zeng, L M., Zhang, Y H., Garland, R M., Su, H., Nowak, A., Wiedensohler, A., Takegawa, N., Shao, M., and Wahner, A.: Exploring the atmospheric chemistry of nitrous acid (HONO) at a rural site in Southern China, Atmos. Chem. Phys., 12, 1497–1513, http://dx.doi.org/10.5194/acp-12-1497-2012doi:10.5194/acp-12-1497-2012, 2012.

Li, Y., Shao, M., Lu, S H., Chang, C C., and Dasgupta, P K.: Variations and sources of ambient formaldehyde for the 2008 Beijing Olympic games, Atmos. Environ., 44, 2632–2639, 2010.

Lou, S., Holland, F., Rohrer, F., Lu, K., Bohn, B., Brauers, T., Chang, C., Fuchs, H., Häseler, R., Kita, K., Kondo, Y., Li, X., Shao, M., Zeng, L., Wahner, A., Zhang, Y., Wang, W., and Hofzumahaus, A.: Atmospheric OH reactivities in the Pearl River Delta – China in summer 2006: measurement and model results, Atmos. Chem. Phys., 10, 11243–11260, http://dx.doi.org/10.5194/acp-10-11243-2010doi:10.5194/acp-10-11243-2010, 2010.

Lu, K D., Zhang, Y H., Su, H., Brauers, T., Chou, C C., Hofzumahaus, A., Liu, S C., Kita, K., Kondo, Y., Shao, M., Wahner, A., Wang, J L., Wang, X S., and Zhu, T.: Oxidant (O3 + NO2) production processes and formation regimes in Beijing, J. Geophys. Res., 115, D07303, http://dx.doi.org/10.1029/2009JD012714doi:10.1029/2009JD012714, 2010.

Lu, K D., Rohrer, F., Holland, F., Fuchs, H., Bohn, B., Brauers, T., Chang, C C., Häseler, R., Hu, M., Kita, K., Kondo, Y., Li, X., Lou, S R., Nehr, S., Shao, M., Zeng, L M., Wahner, A., Zhang, Y H., and Hofzumahaus, A.: Observation and modelling of OH and HO2 concentrations in the Pearl River Delta 2006: a missing OH source in a VOC rich atmosphere, Atmos. Chem. Phys., 12, 1541–1569, http://dx.doi.org/10.5194/acp-12-1541-2012doi:10.5194/acp-12-1541-2012, 2012.

Mao, J., Ren, X., Chen, S., Brune, W H., Chen, Z., Martinez, M., Harder, H., Lefer, B., Rappenglück, B., Flynn, J., and Leuchner, M.: Atmospheric oxidation capacity in the summer of Houston 2006: Comparison with summer measurements in other metropolitan studies, Atmos. Environ., 44, 4107–4115, http://dx.doi.org/10.1016/j.atmosenv.2009.01.013doi:10.1016/j.atmosenv.2009.01.013, 2010.

Mao, J., Ren, X., Zhang, L., Van Duin, D. M., Cohen, R. C., Park, J.-H., Goldstein, A. H., Paulot, F., Beaver, M. R., Crounse, J. D., Wennberg, P. O., DiGangi, J. P., Henry, S. B., Keutsch, F. N., Park, C., Schade, G. W., Wolfe, G. M., Thornton, J. A., and Brune, W. H.: Insights into hydroxyl measurements and atmospheric oxidation in a California forest, Atmos. Chem. Phys., 12, 8009–8020, http://dx.doi.org/10.5194/acp-12-8009-2012doi:10.5194/acp-12-8009-2012, 2012.

Martinez, M., Harder, H., Kovacs, T A., Simpas, J B., Bassis, J., Lesher, R., Brune, W H., Frost, G J., Williams, E J., Stroud, C A., Jobson, B T., Roberts, J M., Hall, S R., Shetter, R E., Wert, B., Fried, A., Alicke, B., Stutz, J., Young, V L., White, A B., and Zamora, R J.: OH and HO2 concentrations, sources, and loss rates during the Southern Oxidants Study in Nashville, Tennessee, summer 1999, J. Geophys. Res., 108, 4617, http://dx.doi.org/10.1029/2003JD003551doi:10.1029/2003JD003551, 2003.

Matsui, H., Koike, M., Kondo, Y., Takegawa, N., Kita, K., Miyazaki, Y., Hu, M., Chang, S Y., Blake, D R., Fast, J D., Zaveri, R A., Streets, D G., Zhang, Q., and Zhu, T.: Spatial and temporal variations of aerosols around Beijing in summer 2006: Model evaluation and source apportionment, J. Geophys. Res., 114, D00G13, http://dx.doi.org/10.1029/2008JD010906doi:10.1029/2008JD010906, 2009.

McKeen, S A., Mount, G., Eisele, F., Williams, E., Harder, J., Goldan, P., Kuster, W., Liu, S C., Baumann, K., Tanner, D., Fried, A., Sewell, S., Cantrell, C., and Shetter, R.: Photochemical modeling of hydroxyl and its relationship to other species during the Tropospheric OH Photochemistry Experiment, J. Geophys. Res., 102, 6467–6493, 1997.

McKenzie, R L. and Kotkamp, M.: Upwelling UV spectral irradiances and surface albedo measurements at Lauder, New Zealand, Geophys. Res. Lett., 23, 1757–1760, 1996.

Mollner, A K., Valluvadasan, S., Feng, L., Sprague, M K., Okumura, M., Milligan, D B., Bloss, W J., Sander, S P., Martien, P T., Harley, R A., McCoy, A B., and Carter, W. P L.: Rate of Gas Phase Association of Hydroxyl Radical and Nitrogen Dioxide, Science, 330, 646–649, 2010.

Monks, P S., Granier, C., Fuzzie, S., Stohl, A., Williams, M., Akimoto, H., Ammani, M., Baklanov, A., Baltensperger, U., Bey, I., Blake, N., Blake, R., Carslaw, K., Cooper, O., Dentener, F., Fowler, D., Fragkou, E., Frost, G., Generoso, S., Ginoux, P., Grewe, V., Guenther, A., Hansson, H C., Henne, S., Hjorth, J., Hofzumahaus, A., Huntrieser, H., Isaksen, I. S A., Jenkin, M E., Kaiser, J., Kanakidou, M., Klimont, Z., Kulmala, M., Laj, P., Lawrence, M., Lee, J., Liousse, C., Maione, M., McFiggans, G., Metzger, A., Mieville, A., Moussiopoulos, N., Orlando, J., O'Dowd, C., Palmer, P., Parrish, D., Petzold, A., Platt, U., Pöschl, U., Prévôt, A. S H., Reeves, C E., Reimann, S., Rudich, Y., Sellegri, K., Steinbrecher, R., Simpson, D., ten Brink, H., Theloke, J., van der Werf, G R., Vautard, R., Vestreng, V., Vlachokostas, C., and vonGlasow, R.: Atmospheric Composition Change – Global and Regional Air Quality, Atmos. Environ., 43, 5268–5350, 2009.

Parrish, D D. and Zhu, T.: Clean Air for Megacities, Science, 326, 674–675, 2009.

Paulot, F., Crounse, J D., Kjaergaard, H G., Kroll, J H., Seinfeld, J H., and Wennberg, P O.: Isoprene photooxidation: new insights into the production of acids and organic nitrates, Atmos. Chem. Phys., 9, 1479–1501, http://dx.doi.org/10.5194/acp-9-1479-2009doi:10.5194/acp-9-1479-2009, 2009.

Peeters, J. and Müller, J.-F.: HO$_\mathrmx$ radical regeneration in isoprene oxidation via peroxy radical isomerisations. II: experimental evidence and global impact, Phys. Chem. Chem. Phys., 12, 14227–14235, http://dx.doi.org/10.1039/c0cp00811gdoi:10.1039/c0cp00811g, 2010.

Peeters, J., Nguyen, T L., and Vereecken, L.: HO$_\mathrmx$ radical regeneration in the oxidation of isoprene, Phys. Chem. Chem. Phys., 11, 5935–5939, 2009.

Poppe, D., Wallasch, M., and Zimmermann, J.: The Dependence of the Concentration of OH on its Precursors under Moderately Polluted Conditions: A Model Study, J. Atmos. Chem., 16, 61–78, 1993.

Pöschl, U., von Kuhlmann, R., Poisson, N., and Crutzen, P J.: Development and intercomparison of condensed isoprene oxidation mechanisms for global atmospheric modeling, J. Atmos. Chem., 37, 29–52, 2000.

Pugh, T. A M., MacKenzie, A R., Hewitt, C N., Langford, B., Edwards, P M., Furneaux, K L., Heard, D E., Hopkins, J R., Jones, C E., Karunaharan, A., Lee, J., Mills, G., Misztal, P., Moller, S., Monks, P S., and Whalley, L K.: Simulating atmospheric composition over a South-East Asian tropical rainforest: performance of a chemistry box model, Atmos. Chem. Phys., 10, 279–298, http://dx.doi.org/10.5194/acp-10-279-2010doi:10.5194/acp-10-279-2010, 2010.

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. Environ., 37, 3639–3651, 2003.

Ren, X., Olson, J R., Crawford, J H., Brune, W H., Mao, J., Long, R B., Chen, G., Avery, M A., Sachse, G W., Barrick, J D., Diskin, G S., Huey, L G., Fried, A., Cohen, R C., Heikes, B., Wennberg, P., Singh, H B., Richard, D. R B., and Shetter, E.: HO$_\mathrmx$ Chemistry during INTEX-A 2004: Observation, Model Calculations and comparison with previous studies, J. Geophys. Res., 113, D05310, http://dx.doi.org/10.1029/2007JD009166doi:10.1029/2007JD009166, 2008.

Richter, A., Burrows, J P., Nüß, H., Granier, C., and Niemeier, U.: Increase of tropospheric nitrogen dioxide over China observed from space, Nature, 437, 129–132, 2005.

Rohrer, F. and Berresheim, H.: Strong correlation between levels of tropospheric hydroxyl radicals and solar ultraviolet radiation, Nature, 442, 184–187, 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, http://dx.doi.org/10.5194/acp-3-161-2003doi:10.5194/acp-3-161-2003, 2003.

Shao, M., Tan, X., Zhang, Y., and Li, W.: City clusters in China: air and surface water pollution, Front. Ecol. Environ., 4, 353–361, 2006.

Sheehy, P M., Volkamer, R., Molina, L T., and Molina, M J.: Oxidative capacity of the Mexico City atmosphere – Part 2: A RO$_\mathrmx$ radical cycling perspective, Atmos. Chem. Phys., 10, 6993–7008, http://dx.doi.org/10.5194/acp-10-6993-2010doi:10.5194/acp-10-6993-2010, 2010.

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, http://dx.doi.org/10.5194/acp-6-2753-2006doi:10.5194/acp-6-2753-2006, 2006.

Stockwell, W R., Kirchner, F., Kuhn, M., and Seefeld, S.: A new mechanism for regional atmospheric chemistry modeling, J. Geophys. Res., 102, 25847–25879, 1997.

Streets, D G., Fu, J S., Jang, C J., Hao, J M., He, K B., Tang, X Y., Zhang, Y H., Wang, Z F., Li, Z P., Zhang, Q., Wang, L T., Wang, B Y., and Yu, C.: Air quality during the 2008 Beijing Olympic Games, Atmos. Environ., 41, 480–492, 2007.

Su, H., Cheng, Y F., Shao, M., Gao, D F., Yu, Z Y., Zeng, L M., Slanina, J., Zhang, Y H., and Wiedensohler, A.: Nitrous acid (HONO) and its daytime sources at a rural site during the 2004 PRIDE-PRD experiment in China, J. Geophys. Res., 113, D14312, http://dx.doi.org/10.1029/2007JD009060doi:10.1029/2007JD009060, 2008.

Takegawa, N., Miyakawa, T., Kuwata, M., Kondo, Y., Zhao, Y., Han, S., Kita, K., Miyazaki, Y., Deng, Z., Xiao, R., Hu, M., van Pinxteren, D., Herrmann, H., Hofzumahaus, A., Holland, F., Wahner, A., Blake, D R., Sugimoto, N., and Zhu, T.: Variability of submicron aerosol observed at a rural site in Beijing in the summer of 2006, J. Geophys. Res., 114, D00G05, http://dx.doi.org/10.1029/2008JD010857doi:10.1029/2008JD010857, 2009.

Tan, D., Faloona, I., Simpas, J B., Brune, W., and Shepson, P B.: HO$\rm_x$ budgets in a deciduous forest: Results from the PROPHET summer 1998 campaign, J. Geophys. Res., 106, 24407–24427, 2001.

Taraborrelli, D., Lawrence, M. G., Butler, T. M., Sander, R., and Lelieveld, J.: Mainz Isoprene Mechanism 2 (MIM2): an isoprene oxidation mechanism for regional and global atmospheric modelling, Atmos. Chem. Phys., 9, 2751–2777, http://dx.doi.org/10.5194/acp-9-2751-2009doi:10.5194/acp-9-2751-2009, 2009.

Toenges-Schuller, N., Stein, O., Rohrer, F., Wahner, A., Richter, A., Burrows, J P., Beirle, S., Wagner, T., Platt, U., and Elvidge, C D.: Global distribution pattern of anthropogenic nitrogen oxide emissions: Correlation analysis of satellite measurements and model calculations, J. Geophys. Res., 111, 312, http://dx.doi.org/10.1029/2005JD006068doi:10.1029/2005JD006068, 2006.

Volkamer, R., Sheehy, P., Molina, L. T., and Molina, M. J.: Oxidative capacity of the Mexico City atmosphere – Part 1: A radical source perspective, Atmos. Chem. Phys., 10, 6969–6991, http://dx.doi.org/10.5194/acp-10-6969-2010doi:10.5194/acp-10-6969-2010, 2010.

Wang, T., Ding, A J., Gao, J., and Wu, W S.: Strong ozone production in urban plumes from Beijing, China, Geophys. Res. Lett., 33, L21806, http://dx.doi.org/10.1029/2006GL027689doi:10.1029/2006GL027689, 2006.

Weinstock, B., Niki, H., and Chang, T Y.: Chemical Factors Affecting the Hydroxyl Radical Concentration in the Troposphere, Adv. Environ. Sci. Technol., 10, 221–258, 1980.

Whalley, L K., Edwards, P M., Furneaux, K L., Goddard, A., Ingham, T., Evans, M J., Stone, D., Hopkins, J R., Jones, C E., Karunaharan, A., Lee, J D., Lewis, A C., Monks, P S., Moller, S J., and Heard, D E.: Quantifying the magnitude of a missing hydroxyl radical source in a tropical rainforest, Atmos. Chem. Phys., 11, 7223–7233, http://dx.doi.org/10.5194/acp-11-7223-2011doi:10.5194/acp-11-7223-2011, 2011.

Wiedensohler, A., Cheng, Y F., Nowak, A., Wehner, B., Achtert, P., Berghof, M., Birmili, W., Wu, Z J., Hu, M., Zhu, T., Takegawa, N., Kita, K., Kondo, Y., Lou, S R., Hofzumahaus, A., Holland, F., Wahner, A., Gunthe, S S., Rose, D., Su, H., and Pöschl, U.: Rapid aerosol particle growth and increase of cloud condensation nucleus activity by secondary aerosol formation and condensation: A case study for regional air pollution in northeastern China, J. Geophys. Res., 114, D00G08, http://dx.doi.org/10.1029/2008JD010884doi:10.1029/2008JD010884, 2009.

Wolfe, G M., Crounse, J D., Parrish, J., J., S., Yoon, T P., Wennberg, P O., and Keutsch, F N.: Photolysis and OH reactivity of a Proxy for Isoprene-derived Hydroperoxyenals, Phys. Chem. Chem. Phys., 14, 7276–7286, http://dx.doi.org/10.1039/c2cp40388adoi:10.1039/c2cp40388a, 2012.

Xie, X., Shao, M., Liu, Y., Lu, S H., Chang, C C., and Chen, Z M.: Estimate of initial isoprene contribution to ozone formation potential in Beijing, China, Atmos. Environ., 42, 6000–6010, 2008.