Authors: Lam, K.S. | Wang, T.J. | Wang, T. | Tang, J. | Kajii, Y. | Liu, C.M. | Shim, S.G.
Surface ozone (O_3 ) was measured at Oki Island (Japan), Cheju Island (South Korea), Lanyu Island (Taiwan Province, China), Cape D' Aguilar (Hong Kong SAR) and Lin'an, Longfenshan, Waliguan (China mainland) during January 1994-December 1996 as a component of IGAC/APARE (International Global Atmospheric Chemistry/East Asia-North Pacific Regional Experiment). This paper gave a joint discussion on the observational results at these stations over the study region. Investigations showed that the average of
…surface O_3 mixing ratios at the seven sites are 47.9 ± 15.8, 48.1 ± 17.9, 30.2 ± 16.4, 31.6 ± 17.5, 36.3 ± 17.5, 34.8 ± 11.5 and 48.2 ± 9.5 ppbv, respectively. Significant diurnal variations of surface O_3 have been observed at Oki, Cheju, D' Aguilar, Lin'an and Longfenshan. Their annual averaged diurnal differences range from 8 to 23 ppbv and differ in each season.Surface O_3 at Lanyu and Waliguan do not show strong diurnal variability. Seasonal cycles of surface O_3 showed difference at the temperate and the subtropical remote sites. Oki has a summer minimum-spring maximum, while Lanyu has a summer minimum-autumn maximum. The suburban sites at D' Aguilar and Lin' an report high-level O_3 in autumn and Iow level O_3 in summer. Surface O_3 remainshigh in autumn and Iow in winter at the rural site Longfenshan. For the global background station Waliguan, surface O_3 exhibits a broad spring-summer maximum and autumn-winter minimum. The backward air trajectories to these sites have shown different pathways of long-range transport of air pollution from East Asia Continent to North Pacific Ocean. Surface O_3 was found to be strongly and positively correlated with CO at Oki and Lanyu, especially in spring and autumn, reflecting the substantial photochemical buildup of O_3 on a regional scale. It is believed that the regional sources of pollution in East Asia have enhanced the average surface O_3 concentrations in the background atmosphere of North Pacific.
Keywords: surface ozone, trajectory, transport, photochemistry
Citation: Journal of Environmental Sciences,
vol. 16, no. 4, pp. 599-609, 2004
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