The impacts of the atmospheric boundary layer on regional haze in North China

An intensive atmospheric boundary layer (ABL) experiment was conducted simultaneously at six stations arranged in a cross shape on the North China Plain (NCP) from 26 November to 26 December 2019. The impacts of the regional ABL structure on heavy haze pollution and the relationship between the ABL...

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Bibliographic Details
Published in:NPJ climate and atmospheric science 2021-02, Vol.4 (1), p.1-10, Article 9
Main Authors: Li, Qianhui, Zhang, Hongsheng, Cai, Xuhui, Song, Yu, Zhu, Tong
Format: Article
Language:English
Subjects:
704/106/35
704/172/4081
Accumulation
Aerodynamics
Air masses
Air pollution
Atmospheric boundary layer
Atmospheric Protection/Air Quality Control/Air Pollution
Atmospheric Sciences
Boundary layers
Climate Change/Climate Change Impacts
Climatology
Diffusion layers
Earth and Environmental Science
Earth Sciences
Fluid dynamics
Haze
Landforms
Mountains
Night
Pollutant removal
Pollutants
Pollution
Spatial distribution
Stations
Vertical distribution
Wind
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Summary:An intensive atmospheric boundary layer (ABL) experiment was conducted simultaneously at six stations arranged in a cross shape on the North China Plain (NCP) from 26 November to 26 December 2019. The impacts of the regional ABL structure on heavy haze pollution and the relationship between the ABL height and aerosol accumulation layer (AAL) depth were discussed. Bouts of downdrafts generate a persistent descending elevated inversion layer, helping the maintenance and exacerbation of haze pollution. Continuous weak wind layers contribute to the pollutants accumulation, and low-level jets promote the removal of air pollutants. The unique landform conditions of the NCP are reflected in its regional ABL structure and further affect the spatial distribution of haze pollution. Due to the drainage flow and strong downdrafts, the western stations near the mountains have a colder surface and warmer upper air masses, resulting in a more stable stratification and worse diffusion conditions; these stations also experience a thicker weak wind layer caused by increased friction. Thus, the spatial distribution of haze is heavier in the west and lighter in the east. The convective boundary layer (CBL) height declines evidently during haze episodes, usually lower than 560 m. Furthermore, as the vertical distribution of aerosols is mainly influenced by daytime thermal turbulence and maintained at night, it is appropriate to determine the CBL height using the AAL depth. However, the AAL depth is not consistent with the stable boundary layer height due to the influence of the residual layer at night.
ISSN:2397-3722
2397-3722
DOI:10.1038/s41612-021-00165-y