Observation And Characteristic Study Of Ozone And Relative Pollutants In Boundary Layer Over Eastern And Southern China

Base on the field study at the high-altitude mountain site — Mount Tai and the typical observation sites in the Pearl River Delta, modern measurement methods of tropospheric ozone and relative pollutants are illustrated together with the set-up and maintenance of multi-species monitoring system. Here the principal and operation of instruments, calibration and quality control/quality assurance procedure are also introduced in detail.Here we report measurement results of ozone (O3) and carbon monoxide (CO) obtained from 5 July to 23 November, 2003 at the summit of Mount Tai (1534 m above sea level, 36.25 °N, 117.10 °E) in the Shandong Peninsula of China. The study was carried out to gain insights into regional O3 pollution and air-mass transport in the highly populated North China (Huabei) Plains. The average mixing ratio was 58 (±16) ppbv for O₃ and 393 (±223) ppbv for CO during the study period. The monthly variations in O₃ and CO exhibited a similar pattern, i.e. high in summer and low in autumn. While such a seasonal pattern for O3 is a common phenomenon in many rural areas in the Northern Hemisphere and is mainly due to seasonal changes in solar radiation and ari temperature, the higher CO levels in summer were attributed to the difference in dynamic transport and the evolution of PBL heights in summer and autumn over this region, also indicates the strong CO emission in North China plain. The forest fire in Eastern Siberia also has some potential effects on simmer time high CO concentration. O3 and CO showed a moderately good positive correlation (r=0.60) in July with a slope of 0.08 ppbv/ppbv, which is much lower than the slope (0.3-0.4 ppbv/ppbv) observed in North America. A back trajectory analysis showed that air masses mainly originated from the North China Plains or were re-circulating over the Shandong Peninsula, collectively accounting for 76% of the air masses sampled. Summertime air traveling in the lower troposphere over northern China had the highest concentrations of O₃ and CO, revealing that the lowertroposphere in northern China was significantly polluted in summer due to strong convection transporting PBL pollution to the lower troposphere. The trajectories also showed notable contributions from eastern China, central China, and countries in northeast Asia such as Korea and Japan.Tropospheric ozone and relative pollutants were also measured at urban site and rural site in PRD during winter and early spring 2004. Here we will discuss the spatial and temporal distribution of ozone and the relative pollutants under different meteorological conditions. It has been proved that Guangzhou, the typical urban site, during winter time, was controlled by Eastern Asia Circulation. Additionally, the site experienced a series of cold front during observation and affected by local meteorological system as well. However under certain conditions, high ozone episodes occur and even last a few days. About 10 episode days with maximum ozone hourly average over 80ppbv have been observed and during these days maximum hourly ozone concentration was as high as 115ppbv. With the help of API contour analysis and study of onsite meteorological data, the occurance of consecutive ozone episodes mostly due to favorable weather conditions and local ozone precursor accumulation. With analysis of chemical composition in different air masses, the characteristics of different emission source are identified and the relationship of pollutant concentration and meteorological factors are also investigated.In Qingyuan, the relative remote site of PRD region, field study was conducted for one and a half month. Ozone and relative pollutants together with meteorological data were measured in purpose of study chemical characteristics of air masses from central China and inland PRD region. Indeed, we found the data got from Qingyuan can be classified into two groups based on wind direction filter, which reflect different emission source characteristic. Seen from ozone diurnal variation in the two air mass groups, northwestern air mass group with low ozone concentration doesn't show significantdiurnal variation while south air mass group shows diurnal variation with ozone getting maximum mixing ratio at about 1400 LT.