Synoptic weather pattern, boundary layer dynamics and air quality in the North China Plain during 2001-2011

Potential relationship between air pollution, synoptic weather patterns and boundary layer dynamics over the North China Plain were analyzed based on air quality data, reanalysis data and daily radiosonde measurement during the time period of 2001-2011. Using a multi-stage classification technique, synoptic weather during the study period was classified into 14 categories. Air pollution index (API) and API increasing index (difference of API between one day and the previous day) at three urban sites (Beijing, Tianjin, Shijiazhuang) in the North China Plain were studied together with boundary layer height calculated from radiosonde and reanalysis data. The statistics results give an overall climatological picture of the main synoptic patterns controlling the boundary layer dynamics and the air quality in the northern China. Cases studies were further conducted to understand the detailed mechanisms, including long-range transport and local dispersion processes, related to typical air pollution episodes. The interannual variation of air quality and synoptical weather conditions were also investigated based on the 12-year data. The results suggested the climate change has an important influence on the trend of air pollution, especially the frequency of heavy pollution episodes in this region.