Source attribution of near-surface ozone trends in the United States during 1995–2019
<p>Emissions of ozone (<span class="inline-formula">O<sub>3</sub></span>) precursors in the United States have decreased in recent decades, and near-surface <span class="inline-formula">O<sub>3</sub></span> concentrations show...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-05-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/23/5403/2023/acp-23-5403-2023.pdf |
| Summary: | <p>Emissions of ozone (<span class="inline-formula">O<sub>3</sub></span>) precursors in the United States have decreased in recent decades, and near-surface <span class="inline-formula">O<sub>3</sub></span> concentrations
showed a significant decrease in summer but an increase in winter. In this study, an <span class="inline-formula">O<sub>3</sub></span> source tagging technique is utilized in a
chemistry–climate model to investigate the source contributions to <span class="inline-formula">O<sub>3</sub></span> mixing ratios in the US from various emitting sectors and regions of nitrogen oxides (<span class="inline-formula">NO<sub><i>x</i></sub></span>) and reactive carbon species during 1995–2019. We show that domestic emission reductions from energy and surface transportation are primarily responsible for the decrease in summertime <span class="inline-formula">O<sub>3</sub></span> during 1995–2019. However, in winter, the emission control also weakens the <span class="inline-formula">NO<sub><i>x</i></sub></span> titration process, resulting in considerable increases in <span class="inline-formula">O<sub>3</sub></span> levels from natural sources. Additionally, increases in aviation and shipping emissions and transpacific transport of <span class="inline-formula">O<sub>3</sub></span> from Asia largely contribute to the winter <span class="inline-formula">O<sub>3</sub></span> increase. We also found that changes in large-scale circulation favoring <span class="inline-formula">O<sub>3</sub></span> transport from the upper atmosphere and foreign transport from Asia also explain 15 % of the increase in the US near-surface <span class="inline-formula">O<sub>3</sub></span> levels in winter.</p> |
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| ISSN: | 1680-7316 1680-7324 |