The thermodynamic structures of the planetary boundary layer dominated by synoptic circulations and the regular effect on air pollution in Beijing
<p>To investigate the impacts of multiscale circulations on the planetary boundary layer (PBL), we have carried out the PBL thermodynamic structure field experiment with a Doppler wind profile lidar, a microwave radiometer, and a ceilometer from January 2018 to December 2019 in Beijing. We fou...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-04-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/21/6111/2021/acp-21-6111-2021.pdf |
| Summary: | <p>To investigate the impacts of multiscale circulations on the
planetary boundary layer (PBL), we have carried out the PBL thermodynamic structure field experiment with a Doppler wind profile lidar, a microwave
radiometer, and a ceilometer from January 2018 to December 2019 in Beijing.
We found that the direct regulatory effect of synoptic circulation worked
through transporting and accumulating pollutants in front of mountains in
the daytime, while the indirect effect of multiscale circulations worked
through coupling mechanisms in the nighttime. The horizontal coupling of
different-direction winds produced a severe pollution convergent zone. The
vertical coupling of upper environmental winds and lower regional breezes
regulated the mixing and diffusion of pollutants by generating dynamic wind
shear and advective temperature inversion. We also found that the dominating synoptic circulations led to great differences in PBL thermodynamic
structure and pollution. The cyclonic circulation resulted in a typical
multilayer PBL characterized by high vertical shear (600 m), temperature
inversion (900 m), and an inhomogeneous stratification. Meanwhile, strong
regional breezes pushed the pollution convergent zone to the south of
Beijing. The southwesterly circulation resulted in a mono-layer PBL
characterized by low vertical shear (400 m) and inversion (200 m). The
westerly circulation led to a hybrid-structure PBL, and the advective
inversion was generated by the vertical shear of zonal winds. Strong
environmental winds of southwesterly and westerly circulations pushed the
severe-pollution zone to the front of mountains. There was no distinct PBL
structure under the anticyclone circulation. The study systematically
revealed the appreciable effects of synoptic and regional circulations on
PBL structure and air quality, which enriched the prediction theory of
atmospheric pollution in the complex terrain.</p> |
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| ISSN: | 1680-7316 1680-7324 |