Mixing layer height and its implications for air pollution over Beijing, China
The mixing layer is an important meteorological factor that affects air pollution. In this study, the atmospheric mixing layer height (MLH) was observed in Beijing from July 2009 to December 2012 using a ceilometer. By comparison with radiosonde data, we found that the ceilometer underestimates...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2016-03-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/16/2459/2016/acp-16-2459-2016.pdf |
| _version_ | 1811338881908342784 |
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| author | G. Tang J. Zhang X. Zhu T. Song C. Münkel B. Hu K. Schäfer Z. Liu J. Zhang L. Wang J. Xin P. Suppan Y. Wang |
| author_facet | G. Tang J. Zhang X. Zhu T. Song C. Münkel B. Hu K. Schäfer Z. Liu J. Zhang L. Wang J. Xin P. Suppan Y. Wang |
| author_sort | G. Tang |
| collection | DOAJ |
| description | The mixing layer is an important meteorological factor that affects
air pollution. In this study, the atmospheric mixing layer
height (MLH) was observed in Beijing from July 2009 to December 2012
using a ceilometer. By comparison with radiosonde data,
we found that the ceilometer underestimates the MLH under conditions of
neutral stratification caused by strong winds, whereas it
overestimates the MLH when sand-dust is crossing. Using
meteorological, PM<sub>2.5</sub>, and PM<sub>10</sub> observational
data, we screened the observed MLH automatically;
the ceilometer observations were fairly consistent with the
radiosondes, with a correlation coefficient greater than 0.9.
Further analysis indicated that the MLH is low in autumn
and winter and high in spring and summer in Beijing. There is a significant
correlation between the sensible heat flux and MLH, and the
diurnal cycle of the MLH in summer is also affected by the circulation of
mountainous plain winds. Using visibility as an index to classify
the degree of air pollution, we found that the variation in the sensible heat and
buoyancy term in turbulent kinetic energy (TKE)
is insignificant when visibility decreases from 10 to 5 km,
but the reduction of shear term in TKE is near 70 %. When
visibility decreases from 5 to 1 km, the variation of
the shear term in TKE is insignificant, but the decrease in the
sensible heat and buoyancy term in TKE is approximately 60 %.
Although the correlation between the daily variation of the MLH and visibility is
very poor, the correlation between them is significantly enhanced when
the relative humidity increases beyond 80 %. This indicates
that humidity-related physicochemical processes is the
primary source of atmospheric particles under heavy pollution and
that the dissipation of atmospheric particles mainly depends on the
MLH. The presented results of the atmospheric mixing layer
provide useful empirical information for improving meteorological and
atmospheric chemistry models and the forecasting and warning of
air pollution. |
| first_indexed | 2024-04-13T18:18:13Z |
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| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-04-13T18:18:13Z |
| publishDate | 2016-03-01 |
| publisher | Copernicus Publications |
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| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-95beabefe240455d81d450c21e7b7a772022-12-22T02:35:37ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242016-03-01162459247510.5194/acp-16-2459-2016Mixing layer height and its implications for air pollution over Beijing, ChinaG. Tang0J. Zhang1X. Zhu2T. Song3C. Münkel4B. Hu5K. Schäfer6Z. Liu7J. Zhang8L. Wang9J. Xin10P. Suppan11Y. Wang12State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, ChinaKey Laboratory of Middle Atmosphere and Global Environment Observation (LAGEO), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, ChinaState Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, ChinaState Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, ChinaVaisala GmbH, 22607 Hamburg, GermanyState Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, ChinaKarlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), 82467 Garmisch-Partenkirchen, GermanyState Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, ChinaState Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, ChinaState Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, ChinaState Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, ChinaKarlsruhe Institute of Technology (KIT), Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), 82467 Garmisch-Partenkirchen, GermanyState Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, ChinaThe mixing layer is an important meteorological factor that affects air pollution. In this study, the atmospheric mixing layer height (MLH) was observed in Beijing from July 2009 to December 2012 using a ceilometer. By comparison with radiosonde data, we found that the ceilometer underestimates the MLH under conditions of neutral stratification caused by strong winds, whereas it overestimates the MLH when sand-dust is crossing. Using meteorological, PM<sub>2.5</sub>, and PM<sub>10</sub> observational data, we screened the observed MLH automatically; the ceilometer observations were fairly consistent with the radiosondes, with a correlation coefficient greater than 0.9. Further analysis indicated that the MLH is low in autumn and winter and high in spring and summer in Beijing. There is a significant correlation between the sensible heat flux and MLH, and the diurnal cycle of the MLH in summer is also affected by the circulation of mountainous plain winds. Using visibility as an index to classify the degree of air pollution, we found that the variation in the sensible heat and buoyancy term in turbulent kinetic energy (TKE) is insignificant when visibility decreases from 10 to 5 km, but the reduction of shear term in TKE is near 70 %. When visibility decreases from 5 to 1 km, the variation of the shear term in TKE is insignificant, but the decrease in the sensible heat and buoyancy term in TKE is approximately 60 %. Although the correlation between the daily variation of the MLH and visibility is very poor, the correlation between them is significantly enhanced when the relative humidity increases beyond 80 %. This indicates that humidity-related physicochemical processes is the primary source of atmospheric particles under heavy pollution and that the dissipation of atmospheric particles mainly depends on the MLH. The presented results of the atmospheric mixing layer provide useful empirical information for improving meteorological and atmospheric chemistry models and the forecasting and warning of air pollution.https://www.atmos-chem-phys.net/16/2459/2016/acp-16-2459-2016.pdf |
| spellingShingle | G. Tang J. Zhang X. Zhu T. Song C. Münkel B. Hu K. Schäfer Z. Liu J. Zhang L. Wang J. Xin P. Suppan Y. Wang Mixing layer height and its implications for air pollution over Beijing, China Atmospheric Chemistry and Physics |
| title | Mixing layer height and its implications for air pollution over Beijing, China |
| title_full | Mixing layer height and its implications for air pollution over Beijing, China |
| title_fullStr | Mixing layer height and its implications for air pollution over Beijing, China |
| title_full_unstemmed | Mixing layer height and its implications for air pollution over Beijing, China |
| title_short | Mixing layer height and its implications for air pollution over Beijing, China |
| title_sort | mixing layer height and its implications for air pollution over beijing china |
| url | https://www.atmos-chem-phys.net/16/2459/2016/acp-16-2459-2016.pdf |
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