Understanding haze pollution over the southern Hebei area of China using the CMAQ model

Abstract Haze has been one of the major air pollution problems in Chinese cities, and the southern Hebei area has attracted particular attention because of its high frequency of haze weather and the rapid deterioration in visibility in recent years. This study is aimed at understanding the characteristics and sources of the serious haze pollution in the southern Hebei area using the Mesoscale Modeling System Generation 5 (MM5) and the Models-3/Community Multiscale Air Quality Model (CMAQ). The haze frequencies in the cities of southern Hebei, including Shijiazhuang, Xingtai, and five other urban centers in the surrounding regions, are analyzed for a ten-year period from 2001 to 2010, which shows a very similar and clear seasonal variation. The contributions of the local and regional anthropogenic emissions to the concentration of fine particulate matter (PM 2.5 , particles with an aerodiameter of less than or equal to 2.5 μm) and the light extinction coefficient ( B ext ) are estimated by conducting simulations of seven scenarios. The results show that approximately 65% of the PM 2.5 in Shijiazhuang and Xingtai originated from the local emissions of the southern Hebei area, followed by Shanxi Province and the northern area of Hebei (13.8% and 7.3% to Shijiazhuang and 10.4% and 5.2% to Xingtai, respectively). The contributions of the emissions from the local area, Shanxi Province and the northern Hebei area to B ext are approximately 59.4%, 13.8% and 6.8% for Shijiazhuang and 58.2%, 10.1% and 5.0% for Xingtai, respectively. Moreover, an analysis of a typical pollution episode indicates that the contributions from the Shandong and Henan provinces are also significant. Further investigations are still required because of the complexity of the haze pollution over the southern Hebei area.