Variations of O3 and CO in summertime at a rural site near Beijing Y. Wang1,2, M. B. McElroy2, J. W. Munger2, J. Hao1, H. Ma1, C. P. Nielsen3, and Y. Chen1 1Department of Environmental Science and Engineering, Tsinghua University, Beijing, China 2Department of Earth and Planetary Sciences and School of Engineering and Applied Sciences, Harvard Univ., Cambridge, Massachusetts, USA 3Harvard China Project and School of Engineering and Applied Sciences, Harvard Univ., Cambridge, Massachusetts, USA
Abstract. Large intra-season differences in mixing ratios of CO and O3 were
detected at Miyun, a rural site north of Beijing, in summer 2006. Despite an
increase in mean daytime mixing ratio of 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.
Citation: Wang, Y., McElroy, M. B., Munger, J. W., Hao, J., Ma, H., Nielsen, C. P., and Chen, Y.: Variations of O3 and CO in summertime at a rural site near Beijing, Atmos. Chem. Phys., 8, 6355-6363, doi:10.5194/acp-8-6355-2008, 2008.