Establishing a conceptual model for photochemical ozone pollution in subtropical Hong Kong

Abstract

h i g h l i g h t s < A conceptual model is for the first time developed for ozone for Hong Kong. < Tropical cyclones are most conducive to the occurrence of high O 3 episodes. < Super-regional and regional transports are other factors that contribute to high O 3 levels in Hong Kong. a b s t r a c tPhotochemical ozone (O 3 ) formation is related to its precursors and meteorological conditions. A conceptual model of O 3 air pollution is developed based on the analysis of data obtained at Tung Chung (TC) in Hong Kong. By comparing meteorological parameters between O 3 and non-O 3 episode days, it was found that high temperatures, strong solar radiation, low wind speeds and relative humidity, northeasterly and/or northwesterly prevailing winds were favorable for the O 3 formation, while tropical cyclones were most conducive to the occurrence of O 3 episodes. Backward trajectories simulation and graphical illustration of O 3 pollution suggested that super-regional (i.e. central and eastern China) and regional (i.e. Pearl River Delta, southern China) transport was another factor that contributed to high O 3 levels in Hong Kong. The photochemical O 3 formation, generally VOC-limited in Hong Kong, was controlled by a small number of volatile organic compounds (VOCs). Furthermore, the positive matrix factorization (PMF) simulation suggested that solvent usage and vehicular emissions are the major contributors to ambient VOCs in Hong Kong. Finally, this paper presents recommendations for further O 3 research and implementation of O 3 control strategies.

Long-term O&lt;sub&gt;3&lt;/sub&gt;–precursor relationships in Hong Kong: field observation and model simulation

“…The RIR values of NO x were lower in spring (−1.15 ± 0.02) and summer (−1.22 ± 0.02) than in autumn (−1.05 ± 0.02) and winter (−1.00 ± 0.01, p < 0.05), suggesting that reducing NO x would increase more O 3 in spring and summer. The aforementioned findings were consistent with the results of previous studies conducted in autumn in Hong Kong, which were based on modelled and observed VOC / NO x ratios (Zhang et al, 2007;Cheng et al, 2010;Ling et al, 2013;Guo et al, 2013). The relationship analyses suggest that the O 3 formation in Hong Kong was VOC-limited in all seasons in these years; that is, the O 3 formation was dominated by AVOCs in winter and was sensitive to both AVOCs and BVOCs in the other three seasons, whereas reducing NO x emissions enhanced O 3 formationthe more so in spring and summer.…”

“…The selection of this site for the trend study was due to its downwind location being a good receptor for urban plume, suffering high O 3 pollution, and having the most comprehensive dataset. More detailed description of the TC site can be found in our previous papers Cheng et al, 2010;Ling et al, 2013;Ou et al, 2015).…”

Ozone pollution around a coastal region of South China Sea: interaction between marine and continental air

“…Hong Kong and the adjacent PRD are the most industrialized regions along the coast of South China Sea (SCS), and they suffer from serious O 3 pollution (Zheng et al, 2010;Guo et al, 2013;Ling et al, 2013). Numerous studies demonstrated that in addition to long-range transport (Chan, 2002;Guo et al, 2009;Wang et al, 2009) and local photochemical production (Ding et al, 2013b), tropical cyclones and mesoscale circulations are conducive to the occurrence of high-O 3 events (Yin, 2004;Huang et al, 2005;Yang et al, 2012;Jiang et al, 2015;Wei et al, 2016).…”

Measuring OVOCs and VOCs by PTR-MS in an urban roadside microenvironment of Hong Kong: relative humidity and temperature dependence, and field intercomparisons

“…The accuracy of each species measured by online GC-FID was determined by the percentage difference between measured mixing ratio and actual mixing ratio based on weekly span checks and monthly calibrations. The precision was based on the 95 % probability limits for the integrated precision check results (Ling et al, 2013;Lyu et al, 2016).…”