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TOAR Workshop 1.03 25–27 January 2016, Beijing

TOAR Workshop 1.03 25–27 January 2016, Beijing Spatial Distribution Characteristics of Air Pollutants and Atmospheric Oxidation Capacity over North China. J. Z. Ma 1 , W. Wang 2 , Y. Chen 1 , H. J. Liu 2 , P. Yan 1 , G. A. Ding 1 , M. L. Wang 1 , J. Sun 1 , and J. Lelieveld 3

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TOAR Workshop 1.03 25–27 January 2016, Beijing

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  1. TOAR Workshop 1.03 25–27 January 2016, Beijing Spatial Distribution Characteristics of Air Pollutants and Atmospheric Oxidation Capacity over North China • J. Z. Ma1, W. Wang2, Y. Chen1, H. J. Liu2, P. Yan1, G. A. Ding1, M. L. Wang1, J. Sun1, and J. Lelieveld3 • 1 Chinese Academy of Meteorological Sciences, Beijing, China; • 2 Chinese Research Academy of Environmental Sciences, Beijing, China; • 3 Max Planck Institute for Chemistry, Mainz, Germany • (mjz@camscma.cn)

  2. Spatial Distribution Characteristics of Air Pollutants and Atmospheric Oxidation Capacity over North China TOAR Workshop 1.03, 25–27 January 2016, Beijing Outline 1. Motivation of this study 2. Overview of field experiment in spring 2006 3. Important measurement and modeling results 4. Conclusions

  3. North China “Huabei” (华北)in Chinese (32-42 ºN of eastern China) A pollution hot spot ! Increase in tropospheric NO2 over North China observed from space (Richter et al., Nature, 2005 Hilboll et al., ACP, 2013) The estimated regional NO2 emissions are about 5% of the global anthropogenic NO2 emissions (B. Zhao et al., ACP, 2012) 1996 2011

  4. High ozone episodes (with 1-hr O3 mixing ratio exceeding 120 ppbv) were frequently observed in urban plumes from Beijing during summertime, with a maximum level of 286 ppbv ! 286 ppbv The year of 2005 T. Wang et al., GRL, 2006

  5. Ozone pollution is synchronism in the urban and rural areas of Beijing. The ozone peak values are found to lag behind one site after another along the route of prevailing wind from SW to NE, due to the transport of both O3 and its precursors. CO emission rates Wind direction rose NOX O3 SDZ: Shangdianzi SY: Shun Yi BL: Bao Lian FT: Feng Tai 20 June – 16 September 2007 J. Xu et al., ACP, 2011

  6. VOCs plays a key role in ozone formation. Measurements of NMHCs and OVOCs at several sites in Beijing and near by provinces show high variability of VOC mixing ratios and chemical speciation. August 2006 M. Shao et al., JGR, 2009

  7. MOZAIC aircraft data analysis shows that O3 in the lower troposphere over Beijing had a strong positive trend (~2% per year from 1995 to 2005). Strong photochemical pollution and regional pollution transport resulted in lower tropospheric O3 maximum especially in the spring-summer period, and similar results were obtained by IASI satellite data analysis. IASI MOZAIC August 2006 A.J. Ding et al., ACP, 2008 Dufour et al., ACP, 2010

  8. Significant increasing trends of tropospheric ozone residue (TOR) during 1979-2005 were found over North China (Huabei), with a maximum rate of 1.10 DU per decade for summer. X.B. Xu and W. L. Lin et al., Adv. Clim. Change Res., 2010

  9. NSFC Key Project: Impact of Air Pollution on Aerosols & Cloud Microphysics in North China (IPAC-NC 2005-2008) (1) to investigate 3-D synchronous distributions of gaseous pollutants, aerosols and cloud microphysical parameters; (2) to assess primarily the impact of air pollution on aerosols and cloud microphysics in North China.

  10. IPAC-NC Field Campaign (2 April-16 May 2006) Shangdianzi station Zhangjiakou 17 research flights (60 hrs) Beijing Tangshan Xin’an station Tianjin Yun-12 Bohai Gulf Shijiazhuang

  11. Primary emissions in the central area of North China (Huabei) B. Zhao et al., ACP, 2012 Percentage contributions from different sources to the NOx mixing ratios in the PBL during IPAC-NC as estimated by our RCTM with a tracer-tagging technique

  12. Model (GRAPES) simulated wind fields and spatial distributions of pollution emitted from major urban centers of Huabei. The model predicts an air pollution pool over the largerBeijing,Tianjin and Tangshan area, where IPAC-NC aircraft measurements took place. Beijing Tangshan Tianjin

  13. The spatial distributions of the major gaseous pollutants measured by aircraft. Widespread high pollutants’ mixing ratios were observed. For instance, over the highly polluted area, SO2 even reached up to 60-100 ppbv in the PBL, much higher than at the surface. Below 1.5km Above 1.5km Below 1.5km Above 1.5km CO CO SO2SO2 NO NO O3O3 NOxNOx OxOx

  14. A decreasing tendency of NO, NOx* and CO with increasing altitude. SO2 shows a maximum at ~0.5 km altitude. The tendency of O3 with altitude is not so clear. Changes in the size distributions of number density and surface area concentration of aerosols with altitude are different.

  15. NCAR’s MM model simulations BASE: standard simulation; NO_S: BASE without considering SO2 related reactions; NO_H: BASE without considering heterogeneous reactions of OH and HO2 on aerosol surfaces ‘1.3*CH2O’: BASE with a 30% increase of CH2O. OH HO2 Our chemical box-model simulations, constrained by the measurements, suggest a maximum in the vertical profiles of OH and HO2 at an altitude of ~1 km over the polluted area of Huabei, due to the combined effective photolysis of ozone and the recycling of radicals in the photochemistry of NO2, CO, VOC and SO2. P(O3)-L(O3)

  16. without HO2 formation with HO2 formation In addition to reactive hydrocarbons and CO, the oxidation of SO2 causes significant ozone production over Huabei (up to ~13% or 2.0 ppbv h-1 at 0.8 km altitude). In the upper part of the boundary layer and in the lower free troposphere, high CO and SO2 compete with relatively less NO2 in reacting with OH, being efficiently recycled through HO2, preventing a net loss of HOx radicals.

  17. New particle formation and growth Condensation on primary emitted particles The high OH levels tend to promote the formation of semi- and low-volatile species such as inorganic and organic acids through the oxidation of SO2, NO2 and VOCs. The aerosol formation rate through the condensation of H2SO4 is estimated to be 2-8 g cm-3 h-1 during the IPAC-NC campaign period, with a maximum at about 0.8 km altitude.

  18. Conclusions • Strong pollution emissions from urban and industrial centers tend to accumulate in the lower atmosphere over the central area of Huabei; • Enhanced levels of OH and HO2 radicals are found to be associated with the high pollution concentrations; • The lower atmosphere over Huabei is not only strongly polluted, but also acts as an oxidation pool, with pollutants undergoing very active photochemistry over this part of China.

  19. 谢谢！Thank you for your attention！

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