Characteristics of trace gaseous pollutants at a regional background station in Northern China Z. Y. Meng, X. B. Xu, P. Yan, G. A. Ding, J. Tang, W. L. Lin, X. D. Xu, and S. F. Wang Key Laboratory for Atmospheric Chemistry, Center for Atmosphere Watch and Services, Chinese Academy of Meteorological Sciences, Beijing 100081, China
Abstract. Measurements of trace gaseous pollutants were taken at the Shangdianzi site,
a WMO Global Atmosphere Watch (GAW) background station in Northern China. The
results are presented for the period from September 2003 to December 2006.
Seasonal and diurnal variations of the O3, NOx, SO2, and
CO concentration are characterized and possible causes for them are
discussed. The observed levels of the trace gases are comparable to those at
some other background sites in polluted regions inside and outside of China.
It was shown that the seasonal variation of O3 can change slightly from
year to year due to the year-to-year alternation in the meteorological
conditions. Higher CO concentrations were observed in some warmer months,
particularly in June and July, 2006. Intensive biomass burning in the North
China Plain region, in combination with the transport of regional pollution
by more frequent southwesterly winds, is believed to be responsible for the
elevated CO concentrations. The diurnal variation of O3, with delayed
peaking times, suggests that the transport of photochemical aged plume is an
important source for O3 at Shangdianzi. The diurnal variations of
SO2 in all seasons show higher values during daytime, contradicting the
common view. An explanation for this unusual phenomenon is hypothesized. To
gain an insight into the impact of transport on the trace gases levels at
Shangdianzi, air mass backward trajectories were calculated and analyzed in
combination with corresponding pollutant concentrations. The results indicate
that the transport of air masses from the North China Plain region and from
the major coal mining regions west of Shangdianzi is responsible for the high
concentrations of the gaseous pollutants.
Citation: Meng, Z. Y., Xu, X. B., Yan, P., Ding, G. A., Tang, J., Lin, W. L., Xu, X. D., and Wang, S. F.: Characteristics of trace gaseous pollutants at a regional background station in Northern China, Atmos. Chem. Phys., 9, 927-936, doi:10.5194/acp-9-927-2009, 2009.