Variations of O₃ and CO in summertime at a rural site near Beijing

Y. Wang (1, 2, 3) , M. B. Mcelroy (3, 1) , J. W. Munger (3) , J. Hao (2) , H. Ma (2) , C. P. Nielsen (4) , Y. Chen (2)

1 SEAS - Harvard John A. Paulson School of Engineering and Applied Sciences
2 Department of Environmental Engineering and Sciences [Beijing]
3 EPS - Department of Earth and Planetary Sciences [Cambridge, USA]
4 Harvard China Project and School of Engineering and Applied Sciences. Harvard University

Large intra-season differences in concentrations of CO and O₃ ([CO], [O₃]) were detected at Miyun, a rural site north of Beijing, in summer 2006. Despite an increase in mean daytime [CO] from 500 ppbv in June to 700 ppbv in July, mean daytime [O₃] dropped from 67 ppbv in June to 50 ppbv in July and August. The observed changes in CO and O₃ are attributed to the influence of the summer monsoonal circulation that develops over the North China Plain in July. Photochemical production of O₃ is reduced as a consequence of increased cloudiness during July and August, as indicated by the strong negative correlation observed between [O₃] and satellite observations of cloud optical depth, with cloudiness having little effect on CO. The analysis suggests a strategy for emission controls that could be implemented in an economically efficient manner to minimize the frequency of high levels of O₃ during summer in Beijing.

Domaines: Océan, Atmosphère

Y. Wang, M. B. Mcelroy, J. W. Munger, J. Hao, H. Ma, et al.. Variations of O₃ and CO in summertime at a rural site near Beijing. Atmospheric Chemistry and Physics Discussions, 2008, 8 (3), pp.10397-10414. ⟨10.5194/acp-8-6355-2008⟩. ⟨hal-00304220⟩