The Observational And Numerical Simulation Study Of Air Pollutions In Typical Region Of Yangtze River Delta

The purpose of this paper is to investigate the variation characteristics of the air pollutants (O3, NO2and SO2) and the impact of the long/short range transport on them in northern suburb of Nanjing, China. Integrating with the back-trajectory model (HYSPLIT4), the cluster analysis and KZ-filter analysis, the air pollutants’characteristics of the mass concentrations, the diurnal variation in different seasons and the impact of long/short range transport on the air pollutants from Jan.2008to Dec.2010were analyzed. And in order to study the spatial and temporal distribution of ozone concentration in Yangtze River Delta and the surrounding areas, ozone concentrations in these regions in January, April, July and October2009were simulated with WRF/Chem model. And a high concentration case of ozone concentration was simulated too.The results showed that the monthly maximum value of O3occurs in May or June, and lowest in December. The monthly mean levels of NO2are high during March and May period, and lowest in august. The minimum value of SO2occurs in June or July. The diurnal variation of O3in different seasons shows a clear peak in the afternoon, ozone concentration is the highest in summer and the lowest in winter. However, the highest levels of NO2and SO2occur in the evening and morning respectively, NO2concentration in summer is lower than that in the other seasons. The diurnal variation of SO2shows two peaks in winter. Long/short range transport is one of the major sources of air pollutants in northern suburb of Nanjing. The results showed that the southwest short-range transport and northwest short-range transport are significantly related to high O3and NO2concentration respectively at this site. The impact to air pollutants is related to the range of transport, which indicates that O3and NO2are regional scale problems in northern suburb of Nanjing. However, the short-range transports which come from east, northeast and southeast are related to high SO2concentration. This indicates that the easterly industrial area may be main factor of which impact the SO2concentration in this site.There is a good correlation between the time series of ozone hour average concentration of model results and observational data, and also between the diurnal variation of model results and observational data. The ozone concentration in Yangtze River Delta is lower than which in the surrounding areas. There is concentration low center in Suzhou and the surrounding regions. The spatial distributions of ozone concentration in the range are different in different seasons. There is a significant difference between the spatial distribution ozone in day and night. The high ozone concentration case showed that it’s not only the photochemical reactions affect the ozone concentration a lot, but also the meteorological factors. High-pressure system can help ozone concentration to reach high level. The emissions in the Yangtze River Delta play an important role of the formation of ozone concentration in Yangtze River Delta. The low ozone concentration region in Yangtze River Delta is associated with local emissions.