Authors: Tijian Wang K S Lam C W Tsang S C Kot
Publish Date: 2004/02/01
Volume: 21, Issue: 1, Pages: 141-152
Abstract
This paper investigates the variability and correlation of surface ozone O3 and carbon monoxide CO observed at Cape D’Aguilar in Hong Kong from 1 January 1994 to 31 December 1995 Statistical analysis shows that the average O3 and CO mixing ratios during the two years are 32±17 ppbv and 305±191 ppbv respectively The O3/CO ratio ranges from 005 to 06 ppbv/ppbv with its frequency peaking at 015 The raw dataset is divided into six groups using backward trajectory and cluster analyses For data assigned to the same trajectory type three groups are further sorted out based on CO and NO x mixing ratios The correlation coefficients and slopes of O3/CO for the 18 groups are calculated using linear regression analysis Finally five kinds of air masses with different chemical features are identified continental background CB marine background MB regional polluted continental RPC perturbed marine PM and local polluted LP air masses Further studies indicate that O3 and CO in the continental and marine background air masses CB and MB are positively correlated for the reason that they are well mixed over the long range transport before arriving at the site The negative correlation between O3 and CO in air mass LP is believed to be associated with heavy anthropogenic influence which results from the enhancement by local sources as indicated by high CO and NO x and depletion of O3 when mixed with fresh emissions The positive correlation in the perturbed marine air mass PM favors the low photochemical production of O3 The negative correlation found in the regional polluted continental air mass RPC is different from the observations at Oki Island in Japan due to the more complex O3 chemistry at Cape D’Aguilar
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