Columnar and surface urban aerosol in the Moscow megacity according to measurements and simulations with the COSMO-ART model
<p>Urban aerosol pollution was analyzed over the Moscow megacity region using the COSMO-ART (COSMO – COnsortium for Small-scale MOdelling, ART – Aerosols and Reactive Trace gases) online coupled mesoscale model system and intensive measurement campaigns at the Moscow State University Meteorolo...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-08-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/22/10443/2022/acp-22-10443-2022.pdf |
| Summary: | <p>Urban aerosol pollution was analyzed over the Moscow
megacity region using the COSMO-ART (COSMO – COnsortium for Small-scale MOdelling, ART – Aerosols and Reactive Trace gases) online coupled
mesoscale model system and intensive measurement campaigns at the Moscow
State University Meteorological Observatory (MSU MO, 55.707<span class="inline-formula"><sup>∘</sup></span> N,
37.522<span class="inline-formula"><sup>∘</sup></span> E) during the April–May period in 2018 and 2019. We analyzed mass concentrations of particulate matter with diameters smaller than 10 <span class="inline-formula">µm</span> (PM<span class="inline-formula"><sub>10</sub></span>), black carbon (BC) and aerosol gas precursors (NO<span class="inline-formula"><sub><i>x</i></sub></span>, SO<span class="inline-formula"><sub>2</sub></span>, CH<span class="inline-formula"><sub><i>x</i></sub></span>) as well as columnar aerosol parameters for fine and coarse modes
together with different meteorological parameters, including an index characterizing the intensity of particle dispersion (IPD). Both model and experimental datasets have shown a statistically significant linear
correlation of BC with NO<span class="inline-formula"><sub>2</sub></span> and PM<span class="inline-formula"><sub>10</sub></span> mass concentrations, which
indicates mostly common sources of emissions of these substances. There was
a pronounced increase in the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">BC</mi><mo>/</mo><msub><mi mathvariant="normal">PM</mi><mn mathvariant="normal">10</mn></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="49pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="4751b8d28e7b5a0be6d0122d4555f232"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-10443-2022-ie00001.svg" width="49pt" height="14pt" src="acp-22-10443-2022-ie00001.png"/></svg:svg></span></span> ratio from 0.7 % to 5.9 %, with the decrease in the IPD index related to the amplification of the atmospheric
stratification. We also found an inverse dependence between the <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M11" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">BC</mi><mo>/</mo><msub><mi mathvariant="normal">PM</mi><mn mathvariant="normal">10</mn></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="49pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="efa8a6a2bc1bc34dcc9d3ec93f979771"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-10443-2022-ie00002.svg" width="49pt" height="14pt" src="acp-22-10443-2022-ie00002.png"/></svg:svg></span></span>
ratio and columnar single-scattering albedo (SSA) for the intense air mixing conditions. This dependence together with the obtained negative correlation
between wind speed and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><mi mathvariant="normal">BC</mi><mo>/</mo><msub><mi mathvariant="normal">PM</mi><mn mathvariant="normal">10</mn></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="49pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="f00c1c7a3734d89d6fb465c0b0dc8e27"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-10443-2022-ie00003.svg" width="49pt" height="14pt" src="acp-22-10443-2022-ie00003.png"/></svg:svg></span></span> may serve as an indicator of changes in the absorbing properties of the atmosphere due to meteorological factors. On
average, the relatively low BC <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mo>/</mo></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="8550e2e9970f84100ffbfa4da4f4f543"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-10443-2022-ie00004.svg" width="8pt" height="14pt" src="acp-22-10443-2022-ie00004.png"/></svg:svg></span></span> PM<span class="inline-formula"><sub>10</sub></span> ratio (for urban regions) of 4.7 % is the cause of the observed relatively high SSA <span class="inline-formula">=</span> 0.94 in Moscow. Using long-term
parallel aerosol optical depth (AOD) measurements over the 2006–2020 period
at the MSU MO and under upwind clean background conditions at Zvenigorod Scientific Station (ZSS) of the IAP RAS (55.7<span class="inline-formula"><sup>∘</sup></span> N, 36.8<span class="inline-formula"><sup>∘</sup></span> E), we estimated the
urban component of AOD (AOD<span class="inline-formula"><sub>urb</sub></span>) and some other parameters as the
differences at these sites. The annual mean AOD<span class="inline-formula"><sub>urb</sub></span> at 550 nm was about
0.021 with more than 85 % of the fine aerosol mode. The comparisons between AOD<span class="inline-formula"><sub>urb</sub></span> obtained from the model and measurements during this experiment have
revealed a similar level of aerosol pollution of about AOD<span class="inline-formula"><sub>urb</sub>=0.015</span>–0.019, which comprised 15 %–19 % of the total AOD at 550 nm. The urban
component of PM<span class="inline-formula"><sub>10</sub></span> (PM<span class="inline-formula"><sub>10urb</sub></span>) was about 16 <span class="inline-formula">µg m<sup>−3</sup></span>
according to the measurements and 6 <span class="inline-formula">µg m<sup>−3</sup></span> according to the
COSMO-ART simulations. We obtained a pronounced diurnal cycle of
PM<span class="inline-formula"><sub>10urb</sub></span> and urban BC (BC<span class="inline-formula"><sub>urb</sub></span>) as well as their strong correlation with the IPDs. With the IPD index change from 3 to 1 at night, there was
about a 4 times increase in PM<span class="inline-formula"><sub>10urb</sub></span> (up to 30–40 <span class="inline-formula">µg m<sup>−3</sup></span>) and a 3 times increase in BC<span class="inline-formula"><sub>urb</sub></span> (up to 3–3.5 <span class="inline-formula">µg m<sup>−3</sup></span>). At the same time, no pronounced daily cycle was found for the columnar urban aerosol
component (AOD<span class="inline-formula"><sub>urb</sub></span>), although there was a slight increase in model
AOD<span class="inline-formula"><sub>urb</sub></span> at night.</p> |
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| ISSN: | 1680-7316 1680-7324 |