ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-9-6217-2009 Increasing surface ozone concentrations in the background atmosphere of Southern China, 1994–2007 Wang T. 1 Wei X. L. 1 Ding A. J. 1 Poon C. N. 1 Lam K. S. 1 Li Y. S. 1 Chan L. Y. 1 Anson M. 2 Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hong Kong, China Faculty of Construction and Land Use, The Hong Kong Polytechnic University, Hong Kong, China 31 08 2009 9 16 6217 6227 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/9/6217/2009/acp-9-6217-2009.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/9/6217/2009/acp-9-6217-2009.pdf

Tropospheric ozone is of great importance with regard to air quality, atmospheric chemistry, and climate change. In this paper we report the first continuous record of surface ozone in the background atmosphere of South China. The data were obtained from 1994 to 2007 at a coastal site in Hong Kong, which is strongly influenced by the outflow of Asian continental air during the winter and the inflow of maritime air from the subtropics in the summer. Three methods are used to derive the rate of change in ozone. A linear fit to the 14-year record shows that the ozone concentration increased by 0.58 ppbv/yr, whereas comparing means in years 1994–2000 and 2001–2007 gives an increase of 0.87 ppbv/yr for a 7-year period. The ozone changes in air masses from various source regions are also examined. Using local wind and carbon monoxide (CO) data to filter out local influence, we find that ozone increased by 0.94 ppbv/yr from 1994–2000 to 2001–2007 in air masses from Eastern China, with similar changes in the other two continent-influenced air-mass groups, but no statistically significant change in the marine air. An examination of the nitrogen dioxide (NO<sub>2</sub>) column obtained from GOME and SCIAMACHY reveals an increase in atmospheric NO<sub>2</sub> in China's three fastest developing coastal regions, whereas NO<sub>2</sub> in other parts of Asia decreased during the same period, and no obvious trend over the main shipping routes in the South China Sea was indicated. Thus the observed increase in background ozone in Hong Kong is most likely due to the increased emissions of NO<sub>2</sub> (and possibly volatile organic compounds (VOCs) as well) in the upwind coastal regions of mainland China. The CO data at Hok Tsui showed less definitive changes compared to the satellite NO<sub>2</sub> column. The increase in background ozone likely made a strong contribution (81%) to the rate of increase in "total ozone" at an urban site in Hong Kong, suggesting the need to consider distant sources when developing long-term strategies to mitigate local ozone pollution.

 References Chameides, W. L., Li, X. S., Tang, X. Y., Zhou, X. J., Luo, C., Kiang, C. S., St John, J., Saylor, R. D., Liu, S. C., Lam, K. S., Wang, T., and Giorgi, F.: Is ozone pollution affecting crop yields in China?, Geophys. Res. Lett., 26, 867–870, 1999. Chan, C. Y., Chan, L. Y., and Harris, J. M.: Urban and background ozone trend in 1984-1999 at subtropical Hong Kong, South China, Ozone-Sci. Eng., 25, 513–522, 2004. Cheung, V. T. F. and Wang, T.: Observational study of ozone pollution at a rural site in the Yangtze Delta of China, Atmos. Environ., 35, 4947–4958, 2001. Chou, C. C. K., Liu, S. C., Lin, C. Y., Shiu, C. J., and Chang, K. H.: The trend of surface ozone in Taipei, Taiwan, and its causes: Implications for ozone control strategies, Atmos. Environ., 40, 3898–3908, 2006. Cohen, D. D., Garton, D., Stelcer, E., Hawas, O., Wang, T., Poon, S., Kim, J., Choi, B. C., Oh, S. N., Shin, H. J., Ko, M. Y., and Uematsu, M.: Multielemental analysis and characterization of fine aerosols at several key ACE-Asia sites, J. Geophys. Res.-Atmos., 109, D19S12, doi:10.1029/2003JD003569, 2004. Crutzen, P.: Discussion of chemistry of some minor constituents in stratosphere and troposphere, Pure Appl. Geophys., 106, 1385–1399, 1973. Dalsøren,~S B., Eide,~M S., Endresen,~Ø., Mjelde,~A., Gravir,~G., and Isaksen,~I S A.: Update on emissions and environmental impacts from the international fleet of ships: the contribution from major ship types and ports, Atmos. Chem. Phys., 9, 2171–2194, 2009. Danielsen, E.: Stratospheric-tropospheric exchange based on radioactivity ozone and potential vorticity, J. Atmos. Sci., 25, 502–518, 1968. Ding, A. J., Wang, T., Thouret, V., Cammas, J. P., and Nédélec, P.: Tropospheric ozone climatology over Beijing: analysis of aircraft data from the MOZAIC program, Atmos. Chem. Phys., 8, 1–13, 2008. Dorling, S. R., Davies, T. D., and Pierce, C. E.: Cluster-analysis – a technique for estimating the synoptic meteorological controls on air and precipitation chemistry – method and applications, Atmos. Environ., 26, 2575–2581, 1992. Draxler, R. R. and Hess, G. D.: An overview of the HYSPLIT_4 modelling system for trajectories, despersion, and deposition, Austral. Meterol. Mag., 47, 295–308, 1998. Eyring, V., H. W. Köhler, J. van Aardenne, and A. Lauer, Emissions from international shipping: 1. The last 50 years, J. Geophys. Res., 110, D17305, doi:10.1029/2004JD005619, 2005. Fiore, A. M., Jacob, D. J., Logan, J. A., and Yin, J. H.: Long-term trends in ground level ozone over the contiguous United States, 1980–1995, J. Geophys. Res.-Atmos., 103, 1471–1480, 1998. Gao, J., Wang, T., Ding, A. J., and Liu, C. B.: Observational study of ozone and carbon monoxide at the summit of mount Tai (1534 m a.s.l.) in central-eastern China, Atmos. Environ., 39, 4779–4791, 2005. IPCC: Climate change 2007 – Synthesis Report, 2007. Jaffe, D., Price, H., Parrish, D. D., Goldstein, A., and Harris, J.: Increasing background ozone during spring on the west coast of North America, Geophys. Res. Lett., 30, 1613, doi:10.1029/2003GL017024, 2003. Jaffe, D. and Ray, J.: Increase in surface ozone at rural sites in the western US, Atmos. Environ., 41, 5452–5463, 2007. Kurokawa., J., Ohara, T., Uno., I., Hayassaki, M., and Tanimoto., H.: Influence of meteorological variability on interannual variations of the springtime boundary layer ozone over Japan during 1981–2005, Atmos. Chem. Phys., Discus., 2009. Lam, K. S., Wang, T. J., Chan, L. Y., Wang, T., and Harris, J.: Flow patterns influencing the seasonal behavior of surface ozone and carbon monoxide at a coastal site near Hong Kong, Atmos. Environ., 35, 3121–3135, 2001. Motulsky, H., Intuitive Biostatistics, Oxford University Press, New York, USA, 91–126, 1995. Naja, M. and Akimoto, H.: Contribution of regional pollution and long-range transport to the Asia-Pacific region: Analysis of long-term ozonesonde data over Japan, J. Geophys. Res.-Atmos., 109, D21306, doi:10.1029/2004JD004687, 2004. Novelli, P. C., Masarie, K. A., Lang, P. M., Hall, B. D., Myers, R. C., and Elkins, J.W.: Reanalysis of tropospheric CO trends: Effects of the 1997–1998 wildfires, J. Geophys. Res.-Atmos., 108(D15), 4464, doi:10.1029/2002JD003031, 2003. Novelli, P. C.: Observational evidence for long-term trends in carbon monoxide, American Geophysical Union, Fall Meeting, Abstract#A11C-0600, 2007. NRC, Committee on Tropospheric Ozone: Rethinking the Ozone Problem in Urban and Regional Air Pollution, 19–40, 1991. Oltmans, S. J., Lefohn, A. S., Harris, J. M., Galbal ly, I., Scheel, H. E., Bodeker, G., Brunke, E.,Claude, H., Tarasick, D., Johnson, B. J., Simmonds, P., Shadwick, D., Anlauf, K., Hayden, K., Schmidlin, F., Fujimoto, T., Akagi, K., Meyer, C., Nichol, S., Davies, J., Redondas, A., and Cuevas, E.: Long-term changes in tropospheric ozone, Atmos. Environ., 40, 3156–3173, 2006. Oltmans, S. J., Lefohn, A. S., Harris, J. M., and Shadwick, D. S.: Background ozone levels of air entering the west coast of the U.S. and assessment of longer-term changes, Atmos. Environ., 42, 6020–6038, 2008. Parrish, D. D., Dunlea, E. J., Atlas, E. L., Schauffler, S., Donnelly, S., Stroud, V., Goldstein, A. H., Millet, D. B., McKay, M., Jaffe, D. A., Price, H. U., Hess, P. G., Flocke, F., and Roberts, J. M.: Changes in the photochemical environment of the temperate North Pacific troposphere in response to increased Asian emissions, J. Geophys. Res.-Atmos., 109, D23S18, doi:10.1029/2004JD004978, 2004. Parrish, D D.,~Millet, D B.,~and~Goldstein, A H.: Increasing ozone in marine boundary layer inflow at the west coasts of North America and Europe, Atmos. Chem. Phys.,~9,~1303-1323,~2009. Richter, A., Burrows, J. P., Nuss, H., Granier, C., and Niemeier, U.: Increase in tropospheric nitrogen dioxide over China observed from space, Nature, 437, 129–132, 2005. Schnadt~Poberaj,~C., Staehelin,~J., Brunner,~D., Thouret,~V., de~Backer,~H., and Stübi,~R.: Long-term changes in UT/LS ozone between the late 1970s and the 1990s deduced from the GASP and MOZAIC aircraft programs and from ozonesondes, Atmos. Chem. Phys., 9, 5343–5369, 2009. Shao, M., Tang, X. Y., Zhang, Y. H., and Li, W. J.: City clusters in China: air and surface water pollution, Front. Ecol. Environ., 4, 353–361, 2006. Tanimoto, H., Mukai, H., Sawa, Y., Matsueda, H., Yonemura, S., Wang, T., Poon, S., Wong, A., Lee, G., Jung, J. Y., Kim, K. R., Lee, M. H., Lin, N. H., Wang, J. L., Ou-Yang, C. F., Wu, C. F., Akimoto, H., Pochanart, P., Tsuboi, K., Doi, H., Zellwegern, C., and Klausenn, J.: Direct assessment of international consistency of standards for ground-level ozone: strategy and implementation toward metrological traceability network in Asia, J. Environ. Monitor., 9, 1183–1193, 2007. Tanimoto, H.: Increase in springtime tropospheic ozone at a mountainous site in Japan for the period 1998–2006, Atmos. Environ., 43, 1358–1363, 2009. Taylor, J. K. and Cihon, C.: Statistical Techniques for data analysis, 2nd edn, Chapman and Hall/CRC, 47–71, 2004. USEPA: EPA's Report on the Environment 2008, EPA/600/R-07/045F, Washington, DC 20460, 2008. Vingarzan, R.: A review of surface ozone background levels and trends, Atmos. Environ., 38, 3431–3442, 2004. Wang, T., Lam, K. S., Chan, L. Y., Lee, A. S. Y., and Carroll, M. A.: Trace gas measurements in coastal Hong Kong during the PEM-West B, J. Geophys. Res.-Atmos., 102, 28575–28588, 1997. Wang, T., Lam, K. S., Lee, A. S. Y., Pang, S. W., and Tsui, W. S.: Meteorological and chemical characteristics of the photochemical ozone episodes observed at Cape D'Aguilar in Hong Kong, J. Appl. Meteorol., 37, 1167–1178, 1998. Wang, T., Cheung, V. T. F., Anson, M., and Li, Y. S.: Ozone and related gaseous pollutants in the boundary layer of Eastern China: Overview of the recent measurements at a rural site, Geophys. Res. Lett., 28, 2373–2376, 2001. Wang, T., Ding, A. J., Blake, D. R., Zahorowski, W., Poon, C. N., and Li, Y. S.: Chemical characterization of the boundary layer outflow of air pollution to Hong Kong during February–April 2001, J. Geophys. Res.-Atmos., 108, 8787, doi:10.1029/2002JD003272, 2003. Wang, T., Guo, H., Blake, D. R., Kwok, Y. H., Simpson, I. J., and Li, Y. S.: Measurements of trace gases in the inflow of South China Sea background air and outflow of regional pollution at Tai O, Southern China, J. Atmos. Chem., 52, 295–317, 2005. Wang, T., Ding, A. J., Gao, J., and Wu, W. S.: Strong ozone production in urban plumes from Beijing, China, Geophys. Res. Lett., 33, 1–5, 2006a. Wang, Z. F., Li, J., Wang, X. Q., Pochanart, P., and Akimoto, H.: Modeling of regional high ozone episode observed at two mountain sites (Mt. Tai and Huang) in East China, J. Atmos. Chem., 55, 253–272, 2006b. Xu, X., Lin, W., Wang, T., Yan, P., Tang, J., Meng, Z., and Wang, Y.: Long-term trend of surface ozone at a regional background station in Eastern China 1991–2006: enhanced variability, Atmos. Chem. Phys., 8, 2595–2607, 2008. Zhang, J., Wang, T., Chameides, W. L., Cardelino, C., Kwok, J., Blake, D. R., Ding, A., and So, K. L.: Ozone production and hydrocarbon reactivity in Hong Kong, Southern China, Atmos. Chem. Phys., 7, 557–573, 2007. Zhang, Y. H., Su, H., Zhong, L. J., Cheng, Y. F., Zeng, L. M., Wang, X. S., Xiang, Y. R., Wang, J. L., Gao, D. F., Shao, M., Fan, S. J., and Liu, S. C.: Regional ozone pollution and observation-based approach for analyzing ozone-precursor relationship during the PRIDE PRD2004 campaign, Atmos. Environ., 42, 6203–6218, 2008. Zhang,~Q., Streets,~D G., Carmichael,~G R., He,~K., Huo,~H., Kannari,~A., Klimont,~Z., Park,~I., Reddy,~S., Fu,~J S., Chen,~D., Duan,~L., Lei,~Y., Wang,~L., and Yao,~Z.: Asian emissions in 2006 for the NASA INTEX-B mission, Atmos. Chem. Phys., 9, 5131–5153, 2009.