The characteristics of abnormal wintertime pollution events in the Jing-Jin-Ji region and its relationships with meteorological factors

Wenhui Zhu; Xiangde Xu; Jun Zheng; Peng Yan; Yinjun Wang; Wenyue Cai

doi:10.1016/j.scitotenv.2018.01.083

The characteristics of abnormal wintertime pollution events in the Jing-Jin-Ji region and its relationships with meteorological factors

Sci Total Environ. 2018 Jun 1:626:887-898. doi: 10.1016/j.scitotenv.2018.01.083. Epub 2018 Feb 19.

Authors

Wenhui Zhu¹, Xiangde Xu², Jun Zheng³, Peng Yan⁴, Yinjun Wang⁵, Wenyue Cai⁶

Affiliations

¹ Nanjing University of Information Science and Technology, Nanjing 210044, China; State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, China.
² State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, China. Electronic address: xuxd@cma.gov.cn.
³ Nanjing University of Information Science and Technology, Nanjing 210044, China.
⁴ Meteorological Observation Center, China Meteorological Administration, Beijing 100081, China.
⁵ State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081, China.
⁶ Nanjing University of Information Science and Technology, Nanjing 210044, China; National Climate Center, China Meteorological Administration, Beijing 100081, China.

PMID: 29898557
DOI: 10.1016/j.scitotenv.2018.01.083

Abstract

Despite the implementation of strict air pollution control measures in recent years, severe haze events were still encountered in the Beijing-Tianjin-Hebei (Jing-Jin-Ji) region during the winter 2016. In this work, seasonal differences in correlations between air pollution and geographic terrain, atmospheric dynamical and thermal structures, and PBL height over the Jing-Jin-Ji region in history and recent years were investigated and a comprehensive model of atmospheric factors affecting winter air pollution formation was proposed. We found that the distribution of PM_2.5 concentration closely correlated with the topography feature of China and the difference in haze pollution intensity between winter and other seasons was the most significant in the Jing-Jin-Ji region. The "semi-enclosed" terrain along with the enhanced winter "downdraft" strongly inhibited the diffusion and convection of air pollutants in this region. Meanwhile, seasonal variations of the vertical thermal structure over the Jing-Jin-Ji region, i.e., the anomalous pattern of "upper warming and bottom cooling" structure in the middle troposphere, and the "weak wind zone" were more distinct in winter 2016 than historical record, providing an important precondition for the frequent occurrence of thermal inversion layers and severe pollution episodes in the lower troposphere. In addition, abnormally low PBL heights occurred in the Jing-Jin-Ji region during severe pollutant episodes in winter 2016, with mean postmeridian PBL height in December of only 869.4 m, the minimum value since 2013. PM_2.5 concentration was not only closely related to PBL height but also the "warm cover" structure in the middle troposphere. The stronger the structure was, the lower the PBL height became, and severer the pollution event was encountered, accompanying water vapor accumulation and intensification of the thermal inversion layer in the lower troposphere. All above observations revealed the mutual feedback correlations between air pollutants concentration and meteorological factors.

Keywords: Atmospheric vertical structure; PBL height; Seasonal variation; Severe wintertime haze pollution; Terrain effect.

MeSH terms

Air Pollutants / analysis*
Air Pollution / statistics & numerical data
Beijing
Environmental Monitoring*
Meteorological Concepts*
Particulate Matter / analysis*
Seasons

Substances

Air Pollutants
Particulate Matter