Research Of The Regional Characteristics Of Gaseous Pollutants And Atmospheric Transport In Beijing And Its Surrounding Areas

Along with the economic development and social progress in China, environmental problems have become sensitive issues, about which people are more concerned than ever before. In recent years, air quality has become one of the key environmental indicators. Reactive gases O3, NO_x, SO₂ and CO are common gaseous polltuants in the atmosphere. They not only have close relationship with human health, but also may have impacts on the climate and ecosystem.In this study, atmospheric reactive gases including O₃, NO, NO₂, NO_x, SO₂ and CO were monitored at three sites in and surrounding Beijing city. The sites are the Beijing urban station, located on the roof of the Training Center of China Meteorological Administration (CMA), the Gucheng (GCH) Integrated Ecological-Meteorological Observation and Experiment Station of Chinese Academy of Meteorological Sciences, located in Hebei Province, and the Shangdianzi (SDZ) regional Global Atmosphere Watch (GAW) station, located in Miyun County. Based on the observational data from June 1, 2008 to May 31, 2009, characteristics of the gaseous pollutants at the sites are studied, including annual averages, averaged diurnal variations in different seasons, spectrum distributions, and seasonal cycles. In addition, the correlations among the gases concentrations and meteorological factors, the variations in the ratios of pollutants concentrations and the possible reasons, and the common sources for the gases, are analyzed and discussed. It is found that the features of SO₂ and CO were similar at CMA and GCH and different from those at SDZ. The feature of NO_x in Beijing was different from those observed at GCH and SDZ due to significant impact from mobile sources such as motor vehicles. The spectrum distributions of O₃ at the three sites look different from each other, suggesting significant differences in O₃ precursors, i.e., NO_x and VOC, and in O3-consuming gases.This thesis also analyzes pollutants transport along transport channels in northern part of North China, which is either northeastwards or southwestwards and nearly parallel to the line connecting the observation sites. The pressure fields and flow fields in Beijing and surrounding areas are classified using Lamb-Jenkinson atmospheric circulation classification methods and the level pressure field data provided by NCEP from 2000 to 2009. 27 circulation patterns are obtained. The circulation controlling the southwest to northeast transport are the patterns C, SW, ASW, CSW and S, occurring in 30% of the time, while the circulation controlling the northeast to southwest transport are the patterns A, NE, ANE, CNE, and N, occuring in 28% of the time. Finally, the variations of gaseous pollutants at three stations during two cases of northeastwards transport and two cases of southwestwards transport are analyzed, together with the atmospheric circulation features and the changes of physical parameters fields. The results of these cases studies show that in the cases of northeastwards transport, CO and SO₂ in the surface layer had a clear time laging trend along the stations'geography alignment, while in the cases of southwestwards transport, the air quality in the whole region could be improved.