Two typical weather patterns of persistent heavy pollution in Beijing - Tianjin - Hebei

3rd International Conference on Energy Engineering and Environmental Protection

能源学;生态环境科学

Rao, Xiaoqin^1 ; Zhang, Hengde^1 ; Zhang, Bihui^1

National Meteorological Center, Beijing

100081, China^1

关键词: Atmospheric static stability;    Atmospheric stratification;    Boundary layer heights;    High relative humidities;    Inversion temperature;    Meteorological elements;    Meteorological modeling;    Secondary transformation;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/227/5/052018/pdf
DOI  :  10.1088/1755-1315/227/5/052018

学科分类：环境科学（综合）

来源: IOP

【 摘 要 】

The persistent heavy pollution weather which occured in Beijing - Tianjin - Hebei from January 26 to 31, 2013 and February 20 to 26, 2014 were compared and analysed by using meteorological elements and air quality observation data and meteorological model field re-analysis data. The results show that both the two events belong to the stagnant accumulation type. The typical configuration of weather system is zonal circulation in 500 hPa, the cold air is not active. The south branch trough is very weak, the condition of water vapor transport is quite poor, which is not conducive to precipitation. The increase of temperature in 800-850 hPa is beneficial to the formation of stable stratification near the ground. Small wind speed near the ground is not conducive to the horizontal diffusion of pollutants. High relative humidity near the ground makes for the hygroscopic growth and secondary transformation of fine particulate. But the mechanism of establishing and maintaining the static and stable situation is different between the two heavy pollution processes. It shows a dry air subsidence area in the middle and low troposphere between 700 hPa and 900 hPa in January 2013. The superposition of subsidence inversion and night radiation inversion in clear sky resulted in extremely stable atmospheric stratification, and the inversion intensity is obviously stronger than that in February 2014. The sinking motion reduces the height of the mixing layer. An extremely low boundary layer height effectively inhibits the vertical diffusion of pollutants, leads to the pollution growing rapidly. The visibility shows obvious diurnal variation with high value in the daytime and extremely low at night in January 2013. While it is a weak rising area of wet air over the polluted area between 850 hPa and near the ground in February 2014. The inversion temperature is not so strong and the height of the mixing layer is a little higher than that in January 2013. The relative humidity of the middle and lower troposphere is high and the cloud cover is more, which results in the less solar radiation received by surface during the daytime, the lower temperature and the higher atmospheric stability. The maintaining of atmospheric static stability makes the pollution gradually accumulating. The visibility always keeps low value at all times in February 2014.