Top-down estimate of China's black carbon emissions using surface observations: Sensitivity to observation representativeness and transport model error

Authors

  • Xuan Wang,

    1. Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Institute for Global Change Studies, Tsinghua University, Beijing, China
    2. School of Environment and State Key Joint Laboratory of Environment Simulation and Pollution, Tsinghua University, Beijing, China
    3. Now at Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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  • Yuxuan Wang,

    Corresponding author
    1. Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Institute for Global Change Studies, Tsinghua University, Beijing, China
    • Corresponding author: Y. X. Wang, Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Institute for Global Change Studies, Tsinghua University, Beijing, China. (yxw@tsinghua.edu.cn)

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  • Jiming Hao,

    1. School of Environment and State Key Joint Laboratory of Environment Simulation and Pollution, Tsinghua University, Beijing, China
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  • Yutaka Kondo,

    1. Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, Tokyo, Japan
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  • Martin Irwin,

    1. Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, Tokyo, Japan
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  • J. William Munger,

    1. Department of Earth and Planetary Sciences and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, USA
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  • Yongjing Zhao

    1. Air Quality Research Center, University of California, Davis, California, USA
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Abstract

[1] This study examines the sensitivity of “top-down” quantification of Chinese black carbon (BC) emissions to the temporal resolution of surface observations and to the transport model error associated with the grid resolution and wet deposition. At two rural sites (Miyun in North China Plain and Chongming in Yangtze River Delta), the model-inferred emission bias based on hourly BC observations can differ by up to 41% from that based on monthly mean observations. This difference relates to the intrinsic inability of the grid-based model in simulating high pollution plumes, which often exert a larger influence on the arithmetic mean of observations at monthly time steps. Adopting the variation of BC to carbon monoxide correlation slope with precipitation as a suitable measure to evaluate the model's wet deposition, we found that wet removal of BC in the model was too weak, due in part to the model's underestimation of large precipitation events. After filtering out the observations during high pollution plumes and large precipitation events for which the transport model error should not be translated into the emission error, the inferred emission bias changed from −11% (without filtering) to −2% (with filtering) at the Miyun site, and from −22% to +1% at the Chongming site. Using surface BC observations from three more rural sites (located in Northeast, Central, and Central South China, respectively) as constraints, our top-down estimate of total BC emissions over China was 1.80 ± 0.65 Tg/yr in 2006, 0.5% lower than the bottom-up inventory of Zhang et al. (2009) but with smaller uncertainty.

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