[A-AS04] Formation of Air Pollution and Its Interactions with Weather/Climate

[AAS04-11] Evolution and Assessment of the Atmospheric Composition in Hangzhou and its Surrounding Areas during the G20 Summit

*Ping Kang¹, Kai Wu², Xiaoling Zhang¹ (1.Plateau Atmosphere and Environment Key Laboratory of Sichuan Province, School of Atmospheric Sciences, Chengdu University of Information Technology, Chengdu, Sichuan 610225, China, 2.Department of Land, Air, and Water Resources, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA)

Keywords:Air quality, Emission reduction, G20 Summit, Ozone sensitivity

To evaluate the effectiveness of control strategies during the G20 Summit (August 24–September 6, 2016), five sites were selected for investigating the variation in air pollution in the city of Hangzhou and its surrounding areas. The results showed that the air quality in Hangzhou greatly improved after the implementation of strict emission controls. Compared to the same dates from the five preceding years, the G20 period exhibited low relative humidity during the early stage and no significant differences in other meteorological conditions. The SO₂, NO₂, PM₁₀, and PM_2.5 concentrations averaged across the five sites in Hangzhou decreased by 42.6%, 57.1%, 36%, and 38.5%, respectively, although the average O₃ concentration increased by 19%. These changes indicate that the emission reduction measures decreased the concentrations of several pollutants. Compared to the same dates from the previous year (August 24–September 6, 2015), the G20 period exhibited significantly decreased concentrations for most of the chemical components of PM_2.5, particularly SO₄^2–, NO₃^–, and NH₄⁺. Additionally, the aerosol optical depth (AOD) and the NO₂ column concentrations followed a trend similar to that of the pollutants in this city.