Ozone weekend effects in the Beijing–Tianjin–Hebei metropolitan area, China 1State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China
10 Mar 2014
2College of Atmospheric Science, Lanzhou University, Lanzhou, 730000, China
3Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
Received: 10 Apr 2013 – Published in Atmos. Chem. Phys. Discuss.: 17 May 2013 Abstract. The ozone weekend effect (OWE) was first investigated in the metropolitan
area of Beijing–Tianjin–Hebei (BTH), China, using in situ measurements from
the Atmospheric Environment Monitoring Network from July 2009 to August
2011. The results indicate that there is an obvious weekly periodical
variation in the surface ozone concentration. There is a lower ozone
concentration from Wednesday to Friday (weekday) and a higher concentration
from Saturday to Monday (weekend) at all the locations of the study.
NOx also displays a weekly cycle, with the maximum level occurring on
weekdays and the minimum level on weekends, especially later on Sunday night
and early Monday morning. This pattern may be responsible for the higher
concentration of ozone on weekends. Additionally, the vertical variations in
O3 and NOx from the 8 m, 47 m, 120 m and 280 m observation
platforms on the 325 m Beijing meteorological tower displayed obvious weekly
cycles that corresponded to the surface results.
Revised: 19 Jan 2014 – Accepted: 23 Jan 2014 – Published: 10 Mar 2014
A smaller decrease in volatile organic compounds (VOCs; using CO as a proxy) and much lower NOx
concentrations on the weekend may lead to higher VOC / NOx ratio, which can
enhance the ozone production efficiency in VOC-limited regime areas.
Additionally, a clear weekly cycle in the fine aerosol concentration was
observed, with maximum values occurring on weekdays and minimum values
occurring on weekends. Higher concentrations of aerosol on weekdays can
reduce the UV radiation flux by scattering or absorbing, which leads to a
decrease in the ozone production efficiency. A significant weekly cycle in
UV radiation, consistent with the aerosol concentration, was discovered at
the Beijing meteorological tower site (BJT), validating the assumption. A comprehensive understanding of
the ozone weekend effect in the BTH area can provide deep insights into
controlling photochemical pollution.
Citation: Wang, Y. H., Hu, B., Ji, D. S., Liu, Z. R., Tang, G. Q., Xin, J. Y., Zhang, H. X., Song, T., Wang, L. L., Gao, W. K., Wang, X. K., and Wang, Y. S.: Ozone weekend effects in the Beijing–Tianjin–Hebei metropolitan area, China, Atmos. Chem. Phys., 14, 2419-2429, doi:10.5194/acp-14-2419-2014, 2014.