Year round measurements of O3 and CO at a rural site near Beijing: variations in their correlations

Authors

  • YUXUAN WANG,

    Corresponding author
    1. Department of Environmental Science and Engineering and State Key Joint Laboratory of Environment Simulation and Pollution, Tsinghua University, Beijing 100084, China
      Corresponding author.
      e-mail: yxw@tsinghua.edu.cn
    Search for more papers by this author
  • JIMING HAO,

    1. Department of Environmental Science and Engineering and State Key Joint Laboratory of Environment Simulation and Pollution, Tsinghua University, Beijing 100084, China
    Search for more papers by this author
  • MICHAEL B. MCELROY,

    1. Department of Earth and Planetary Sciences and School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
    Search for more papers by this author
  • J. WILLIAM MUNGER,

    1. Department of Earth and Planetary Sciences and School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
    Search for more papers by this author
  • HONG MA,

    1. Department of Environmental Science and Engineering and State Key Joint Laboratory of Environment Simulation and Pollution, Tsinghua University, Beijing 100084, China
    Search for more papers by this author
  • CHRIS P. NIELSEN,

    1. Harvard China Project and School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
    Search for more papers by this author
  • YUQIANG ZHANG

    1. Department of Environmental Science and Engineering and State Key Joint Laboratory of Environment Simulation and Pollution, Tsinghua University, Beijing 100084, China
    Search for more papers by this author

Corresponding author.
e-mail: yxw@tsinghua.edu.cn

ABSTRACT

We examine seasonal variations of carbon monoxide (CO), ozone (O3), and their relationships observed over the course of 3 yr (2005–2007) at Miyun, a rural site 100 km north of Beijing. Monthly mean afternoon mixing ratios of CO have broad maxima in winter and a secondary peak in June. Monthly mean afternoon O3 shows a clear seasonal pattern with a major peak in June (85 ppb), a secondary peak in September (65 ppb) and minimum in winter (50–55 ppb). The seasonal cycles of O3 and CO are associated with seasonal changes in dominant synoptic pattern. Substantial interannual variability is found for CO which is attributed to the interannual variability of meteorology and emissions from biomass burning. The seasonality and magnitude of background CO and O3 derived at Miyun are consistent with observations at upwind remote continental sites. The O3–CO correlation slope is about 0.07 ppb ppb−1 on average in summer, significantly lower than the typical slope of 0.3 ppb ppb−1 reported for developed countries. The O3–CO correlation slope shows large gradients for different types of air masses (0.133 ± 0.017 ppb ppb−1 in aged urban pollution plumes and 0.047 ± 0.008 ppb ppb−1 in biomass burning plumes), suggesting that the conventional method of direct scaling the mean O3–CO slope by CO emissions to deduce O3 production rate is subject to large uncertainties if applied for China.

Ancillary