Articles | Volume 16, issue 14
Research article
27 Jul 2016
Research article |  | 27 Jul 2016

Insights into a historic severe haze event in Shanghai: synoptic situation, boundary layer and pollutants

Chunpeng Leng, Junyan Duan, Chen Xu, Hefeng Zhang, Yifan Wang, Yanyu Wang, Xiang Li, Lingdong Kong, Jun Tao, Renjian Zhang, Tiantao Cheng, Shuping Zha, and Xingna Yu

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.

Short summary
Meteorological conditions, local anthropogenic emissions and aerosol properties played major roles in this historic winter haze weather formation. Aerosols the size of 600–1400 nm are mostly responsible for the impairment of atmospheric visibility. This study was performed by combining many on-line measurement techniques which were calibrated regularly to ensure reliability, and can act as a reference for forecasting and eliminating the occurrences of regional atmospheric pollutions in China.
Final-revised paper