Mixing layer transport flux of particulate matter in Beijing, China
<p>Quantifying the transport flux (TF) of atmospheric pollutants plays an important role in understanding the causes of air pollution and in making decisions regarding the prevention and control of regional air pollution. In this study, the mixing layer height (MLH) and wind profile were measu...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-07-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/19/9531/2019/acp-19-9531-2019.pdf |
| Summary: | <p>Quantifying the transport flux (TF) of atmospheric pollutants plays an
important role in understanding the causes of air pollution and in making
decisions regarding the prevention and control of regional air pollution. In
this study, the mixing layer height (MLH) and wind profile were measured by a
ceilometer and Doppler wind radar, respectively, and the characteristics of
the atmospheric dilution capability were analyzed using these two datasets.
The ventilation coefficient (VC) appears to be the highest in the spring (<span class="inline-formula">3940±2110</span> m<span class="inline-formula"><sup>2</sup></span> s<span class="inline-formula"><sup>−1</sup></span>) and lower in the summer (<span class="inline-formula">2953±1322</span> m<span class="inline-formula"><sup>2</sup></span> s<span class="inline-formula"><sup>−1</sup></span>), autumn (<span class="inline-formula">2580±1601</span> m<span class="inline-formula"><sup>2</sup></span> s<span class="inline-formula"><sup>−1</sup></span>) and winter
(<span class="inline-formula">2913±3323</span> m<span class="inline-formula"><sup>2</sup></span> s<span class="inline-formula"><sup>−1</sup></span>). Combined with the backscatter
measured by the ceilometer, vertical profiles of the PM<span class="inline-formula"><sub>2.5</sub></span>
concentration were obtained and the PM<span class="inline-formula"><sub>2.5</sub></span> TF in the mixing layer was
calculated. The TF was the highest in the spring at <span class="inline-formula">4.33±0.69</span> mg m<span class="inline-formula"><sup>−1</sup></span> s<span class="inline-formula"><sup>−1</sup></span> and lower in the summer, autumn and winter, when the TF
values were <span class="inline-formula">2.27±0.42</span>, <span class="inline-formula">2.39±0.45</span> and <span class="inline-formula">2.89±0.49</span> mg m<span class="inline-formula"><sup>−1</sup></span> s<span class="inline-formula"><sup>−1</sup></span>, respectively.
Air pollutants transport mainly occurs between 14:00 and 18:00 LT. The TF
was large in the pollution transition period (spring: <span class="inline-formula">5.50±4.83</span> mg m<span class="inline-formula"><sup>−1</sup></span> s<span class="inline-formula"><sup>−1</sup></span>; summer: <span class="inline-formula">3.94±2.36</span> mg m<span class="inline-formula"><sup>−1</sup></span> s<span class="inline-formula"><sup>−1</sup></span>; autumn:
<span class="inline-formula">3.72±2.86</span> mg m<span class="inline-formula"><sup>−1</sup></span> s<span class="inline-formula"><sup>−1</sup></span>; winter: <span class="inline-formula">4.45±4.40</span> mg m<span class="inline-formula"><sup>−1</sup></span> s<span class="inline-formula"><sup>−1</sup>)</span> and decreased during the heavy pollution period (spring:
<span class="inline-formula">4.69±4.84</span> mg m<span class="inline-formula"><sup>−1</sup></span> s<span class="inline-formula"><sup>−1</sup></span>; summer: <span class="inline-formula">3.39±1.77</span> mg m<span class="inline-formula"><sup>−1</sup></span> s<span class="inline-formula"><sup>−1</sup></span>; autumn: <span class="inline-formula">3.01±2.40</span> mg m<span class="inline-formula"><sup>−1</sup></span> s<span class="inline-formula"><sup>−1</sup></span>; winter:
<span class="inline-formula">3.25±2.77</span> mg m<span class="inline-formula"><sup>−1</sup></span> s<span class="inline-formula"><sup>−1</sup></span>). Our results indicate that the
influence of the air pollutants transport in the southern regions should
receive more focus in the transition period of pollution, while local
emissions should receive more focus in the heavy pollution period.</p> |
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| ISSN: | 1680-7316 1680-7324 |