Insights into a historic severe haze event in Shanghai: synoptic situation, boundary layer and pollutants
- 1Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP), Department of environmental science and engineering, Fudan University, Shanghai 200433, China
- 2Atmospheric Environment Institute, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
- 3South China Institute of Environmental Sciences, Ministry of Environmental Protection, Guangzhou 510655, China
- 4Key Laboratory of Region Climate-Environment Research for Temperate East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
- 5Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology, Nanjing 210044, China
Abstract. A historic haze event, characterized by lengthy, large-scale and severe pollution, occurred in the Yangtze River Delta (YRD) of China from 1 to 10 December 2013. This haze event significantly influenced air quality throughout the region, especially in urban areas. Aerosol physical, chemical and optical properties were measured in Shanghai. Sometimes the 1 h average particle concentration (e.g., PM2.5) exceeded 600 µg m−3. Inorganic water-soluble ions in particles, trace gases and aerosol optical coefficients had a similar tendency to increase evidently from clear to hazy episodes. A combination of various factors contributed to the formation and evolution of the haze event, among which meteorological conditions, local anthropogenic emissions and pollutants are the major factors. High pressure system, calm surface wind and subsidence airflow were responsible for the decrease of planetary boundary layer (PBL) and the accumulation of pollutants. Atmospheric visibility correlated strongly with relative humidity (RH), particle number in size of 600–1400 nm other than particulate water-soluble species and particle mass (PM2.5). The particle hygroscopicity plays an important role in atmospheric visibility reduction. The results are somewhat helpful to forecast and eliminate regional atmospheric pollution in China.