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From October 5-13, 2014, eastern China experienced a severe air pollution and haze event, which affected unusually sizeable areas and lasted for a long period. In order to better understand the characteristics of the episode and to study its meteorological reasons and formation processes, this paper performs statistical analyses of temporal-spatial distribution of the air pollution using AQI (Air Quality Index) data. The present study employed NCEP (National Centers for Environmental Prediction) reanalysis and meteorological data from the surface and high-balloon stations to analyze the main system patterns, weather conditions and wind fields in the PBL (planetary boundary layer) and the upper air during the episode. The results showed that: 1) the North China Plain and the Northeast China Plain were the most polluted areas in this episode. Lasting pollution in each city was the main characteristic of the episode. The time variation of the heavy air pollution process could be divided into three stages, including AQI ascent, lasting pollution and AQI descent. 2) During the AQI ascent stage (October 6-8), the anticyclone in eastern China showed a local and a south weak wind field at the surface and strong temperature inversion at 3000 m, which are favorable for pollution accumulation. The weather conditions provided valuable interpretation for dramatic AQI ascent. 3) During the lasting pollution stage (October 8-11), the stagnation of the anticyclone over the sea and typhoon “Yongfong” gave rise to lasting eastern and southern winds in the East China Plain for four days, which were important factors in the lasting pollution episode. 4) The front of the follow-up anticyclone (October 11-12) was favorable for pollution removal, which was the main system pattern for the AQI descent. In conclusion, the lasting stable system pattern was the main meteorological reason for this episode. ©, 2015, Editorial department of Molecular Catalysis. All right reserved.
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