A CASE STUDY OF POLLUTION PROCESS IN NORTH CHINA REGION USING REANALYSIS METEOROLOGY

Haze pollution events have been a hot topic in recent year due to their serious impacts on human health, environment, and even climate, particularly over East Asia regions. A special pollution process occurred in January 2017 is analyzed in this study based on reanalysis meteorolgoy data and surface PM2.5 observations. Based on mesoscale and local meteorology, along with the surface PM2.5 observations, this study investigates the formation, accumulation, and disperse of a haze events occurred in Baoding, China during the period from January 27 to 29 in 2017. It shows that the fast accumulation of PM2.5 mass concentration at the early stage of haze formation is highly related to the weak southwest winds behind the high pressure system on January 27. On January 28, Baoding lied between the high pressure and low pressure systems, the convergence of winds made aerosols accumulate in this region, causing very heavy pollution with high PM2.5 mass concentrations. Moreover, the vertical profile of temperature measured in Beijing shows that the temperature lapse rate decreased on January 28, making the aerosol particles more difficult to disperse. On January 29, when the high pressure dominates with strong north winds, the haze disappeared.