Elevated dust layers inhibit dissipation of heavy anthropogenic surface air pollution
<p>Persistent wintertime heavy haze incidents caused by anthropogenic aerosols have repeatedly shrouded North China in recent years, while natural dust from the west and northwest of China also frequently affects air quality in this region. Through continuous observation by a multi-wavelength...
| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-12-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/20/14917/2020/acp-20-14917-2020.pdf |
| Summary: | <p>Persistent wintertime heavy haze incidents caused by
anthropogenic aerosols have repeatedly shrouded North China in recent years,
while natural dust from the west and northwest of China also frequently affects
air quality in this region. Through continuous observation by a
multi-wavelength Raman lidar, here we found that wintertime aerosols in
North China are typically characterized by a pronounced vertical
stratification, where scattering nonspherical particles (dust or mixtures
of dust and anthropogenic aerosols) dominated above the planetary boundary
layer (PBL), and absorbing spherical particles (anthropogenic aerosols)
prevailed within the PBL. This stratification is governed by meteorological
conditions that strong northwesterly winds usually prevailed in the lower
free troposphere, and southerly winds dominated in the PBL, producing
persistent and intense haze pollution. With the increased contribution of
elevated dust to the upper aerosols, the proportion of aerosol and trace gas
at the surface in the whole column increased. Model results show that,
besides directly deteriorating air quality, the key role of the elevated
dust is to depress the development of PBL and weaken the turbulent
exchange, mostly by lower level cooling and upper level heating, and it is
more obvious during the dissipation stage, thus inhibiting the dissipation of
heavy surface anthropogenic aerosols. The interactions of natural dust and
anthropogenic aerosols under the unique topography of North China increase
the surface anthropogenic aerosols and precursor gases, which may be one of
the reasons why haze<span id="page14918"/> pollution in North China is heavier than that in other
heavily polluted areas in China.</p> |
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| ISSN: | 1680-7316 1680-7324 |