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Mixing layer transport flux of particulate matter in Beijing, China

Mixing layer transport flux of particulate matter in Beijing, China. Guiqian Tang, Xiaowan Zhu, Yusi Liu, Libo Zhou, Bo Hu, Yuesi Wang. Institute of Atmospheric Physics, Chinese Academy of Sciences. April, 2019. Motivation. PM 2.5. WHO 35 μ g/m 3.

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Mixing layer transport flux of particulate matter in Beijing, China

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  1. Mixing layer transport flux of particulate matter in Beijing, China Guiqian Tang, Xiaowan Zhu, Yusi Liu, Libo Zhou, Bo Hu, Yuesi Wang Institute of Atmospheric Physics,Chinese Academy of Sciences April, 2019

  2. Motivation PM2.5 WHO 35μg/m3 Great pressure to ensure continuous decline of PM. Regional pollution → Joint prevention and control (Shen et al., 2019, STE; Cheng et al., 2018, ACPD)

  3. Main targets Red alert of air pollution in China → close nearly all the industries How to implement joint emission control at the lowest economic cost? • What are the responses of particulate matter to boundary layer meteorology • When and where should be controlled during heavy pollution episodes ? ?

  4. Methods Vertical dilution capacity Horizontal dilution capacity Vertical aerosols profile Mixing layer height Vertical wind profile Doppler wind radar Ceilometer CL51

  5. Methods Uniform vertical backscatter coefficient → using ground PM concentration to represent the average concentration in ML Flux = VC × C PM2.5

  6. Periodicity of PM,MLH and RH Sawtooth PM cycle Sawtooth MLH and RH The connection between boundary meteorology and air quality (Tang et al., ACP, 2016; Zhu, Tang*, JGR, 2016)

  7. Responses of PM to boundary layer meteorology in winter PM2.5 concentration is highly sensitive to boundary layer meteorology in winter. Weak atmospheric dilution capability is a crucial factor leading to serious air pollution in Beijing. (Liu, Tang* et al.,2019, ACPD)

  8. Responses of PM to boundary layer meteorology in summer Weak positive correlation in summer Secondary particles because of high ozone ? (Liu, Tang* et al.,2019, ACPD)

  9. Responses of PM to boundary layer meteorology in summer Inconsistent diurnal cycles of ozone and PM Secondary formation is not the main reason.

  10. Mountainous plain winds in Beijing Strong southwest winds in the afternoon, but northly winds before the next day’s afternoon. (Tang et al., 2016, ACP; Liu, Tang* et al.,2019, ACPD)

  11. Impact of mountainous plain winds on particulate matter June as an example The circulation of mountain plain winds leads to high PM2.5 before noon. (Liu, Tang* et al.,2019, ACPD)

  12. Transport flux under different degrees of air pollution • Regional transport plays an important role in the transition period of pollution. • Local emissions are the main controlling factor during the period of heavy pollution . (Tang et al,, 2015, ACP; Liu, Tang* et al.,2019, ACPD)

  13. Summary • PM2.5 concentration is highly sensitive to boundary layer meteorology. • The mountainous plain circulation influence the air quality in summer. • In the transition period of air pollution, the focus should be on controlling the emissions in the south of Beijing.

  14. Thank you for your attention!

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