Analysis about the Characteristics and Formation Mechanism of a Serious Pollution Event in Beijing in October 2014.

In this paper, atmospheric environmental background, weather conditions and formation mechanism of one typical air pollution episode in Beijing during October 6th -12th, 2014 were investigated by combining observed data with numerical model CAMx. Results showed that the occurrence of heavy air pollution resulted mainly from stable atmospheric conditions regionally or locally. Observed heavy pollution episodes were characterized by a stagnant atmospheric structure with average wind speed of 1.56 m/s, high humidity of 83.13%, large inversion strength of 3.42 cC/100 m which were disadvantageous to the dispersal of air pollutants. The air pollution episode during October 8th -11th was the most serious with daily average PM25 concentration of 264 μ/m³ in Beijing, and heavily polluted land area at Beijing, Tianjin and Hebei districts was about 2 × 105 km². Model research showed that regional transmission contributions to the receptor sites in Beijing were between 61% -69% during 8th -11th, and regional transportation played a more important role in this serious air pollution episode. [ABSTRACT FROM AUTHOR]