Ozone production and hydrocarbon reactivity in Hong Kong, Southern China J. Zhang1,2, T. Wang3, W. L. Chameides1, C. Cardelino1, J. Kwok3, D. R. Blake4, A. Ding3, and K. L. So3 1School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA 2School of Geography, Beijing Normal University, Beijing 100875, China 3Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hong Kong 4Department of Chemistry, University of California, Irvine, CA 92697, USA
Abstract. Data obtained in Hong Kong during the Hong Kong and the Pearl River Delta
(PRD) Pilot Air Monitoring Study in autumn 2002 are analyzed to unravel the
relationship between ground-level ozone (O3), pollution precursors, and
cross-border transport. Ten ozone episodes, during which the hourly O3
concentration exceeded 100 ppbv in 9 cases and 90 ppbv in one case, are
subject to detailed analysis, including one case with hourly O3 of 203 ppbv,
which is the highest concentration on record to date in Hong Kong.
Combined with high-resolution back trajectories, dCO/dNOy (the ratio of
enhancement of CO concentration above background to that of NOy) is
used to define whether O3 is locally or regionally produced. Five out
of the ten Hong Kong O3-episodes studied show a "pollution signature"
that is indicative of impact from Guangdong Province. Examination of
speciated volatile organic compounds (VOCs) shows that the reactivity of
VOCs is dominated by anthropogenic VOCs, of which the reactive aromatics
dominate, in particular xylenes and toluene. Calculations using a
photochemical box model indicate that between 50–100% of the O3
increase observed in Hong Kong during the O3 episodes can be explained
by photochemical generation within the Hong Kong area, provided that nitrous
acid (HONO) is present at the concentrations derived from this study. An
Observation-Based Model (OBM) is used to calculate the sensitivity of the
O3 production to changes in the concentrations of the precursor
compounds. Generally the production of O3 throughout much of the Hong
Kong area is limited by VOCs, while high nitric oxide (NO) concentrations
suppress O3 concentration.
Citation: 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, doi:10.5194/acp-7-557-2007, 2007.