Insights into ozone pollution control in urban areas by decoupling meteorological factors based on machine learning
<p>Ozone (O<span class="inline-formula"><sub>3</sub></span>) pollution is posing significant challenges to urban air quality improvement in China. The formation of surface O<span class="inline-formula"><sub>3</sub></span> is i...
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| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-02-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/25/1749/2025/acp-25-1749-2025.pdf |
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| Summary: | <p>Ozone (O<span class="inline-formula"><sub>3</sub></span>) pollution is posing significant challenges to urban air quality improvement in China. The formation of surface O<span class="inline-formula"><sub>3</sub></span> is intricately linked to chemical reactions which are influenced by both meteorological conditions and local emissions of precursors (i.e., NO<span class="inline-formula"><sub><i>x</i></sub></span> and volatile organic compounds, VOCs). When meteorological conditions deteriorate, the atmosphere's capacity to cleanse pollutants decreases, leading to the accumulation of air pollutants. Although a series of emission reduction measures have been implemented in urban areas, the effectiveness of O<span class="inline-formula"><sub>3</sub></span> pollution control proves inadequate. Primarily due to adverse changes in meteorological conditions, the effects of emission reduction are masked. In this study, we integrated a machine learning model, an observation-based model, and a positive matrix factorization model based on 4 years of continuous observation data from a typical urban site. We found that transport and dispersion impact the distribution of O<span class="inline-formula"><sub>3</sub></span> concentration. During the warm season, positive contributions of dispersion and transport to O<span class="inline-formula"><sub>3</sub></span> concentration ranged from 12.9 % to 24.0 %. After meteorological normalization, the sensitivity of O<span class="inline-formula"><sub>3</sub></span> formation and the source apportionment of VOCs changed. The sensitivity of O<span class="inline-formula"><sub>3</sub></span> formation shifted towards the transition regime between VOC- and NO<span class="inline-formula"><sub><i>x</i></sub></span>-limited regimes during the O<span class="inline-formula"><sub>3</sub></span> pollution event. Vehicle exhaust became the primary source of VOC emissions after “removing” the effect of dispersion, contributing 41.8 % to VOCs during the pollution periods. On the contrary, the contribution of combustion to VOCs decreased from 33.7 % to 25.1 %. Our results provided new recommendations and insights for implementing O<span class="inline-formula"><sub>3</sub></span> pollution control measures and evaluating the effectiveness of emission reduction in urban areas.</p> |
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| ISSN: | 1680-7316 1680-7324 |