Comparative ozone production sensitivity to NO<sub><i>x</i></sub> and VOCs in Quito, Ecuador, and Santiago, Chile
<p>Amid the current climate and environmental crises, cities are being called to reduce levels of atmospheric pollutants that also act as short-lived climate forcers, such as ozone and PM<span class="inline-formula"><sub>2.5</sub></span>. This endeavor present...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-07-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/25/7087/2025/acp-25-7087-2025.pdf |
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| Summary: | <p>Amid the current climate and environmental crises, cities are being called to reduce levels of atmospheric pollutants that also act as short-lived climate forcers, such as ozone and PM<span class="inline-formula"><sub>2.5</sub></span>. This endeavor presents new challenges, especially in understudied regions. Here, we use a chemical box model to investigate ozone production sensitivity to NO<span class="inline-formula"><sub><i>x</i></sub></span> and VOCs in Quito, Ecuador, and Santiago, Chile. We present ozone production rates (<span class="inline-formula"><i>P</i></span>(O<span class="inline-formula"><sub>3</sub></span>)) calculated using VOC measurements taken in Santiago, along with VOC vs. CO linear regressions (LRs), and complement the analysis with Monte Carlo (MC) simulations. In Quito, VOC measurements are unavailable. We therefore simulated a range of VOC concentrations using LRs and MC simulations. We modeled <span class="inline-formula"><i>P</i></span>(O<span class="inline-formula"><sub>3</sub></span>) in March 2021 and for typical conditions per season in 2022. We calculated a range of <span class="inline-formula"><i>P</i></span>(O<span class="inline-formula"><sub>3</sub></span>) in Quito of 15–50 ppbv h<span class="inline-formula"><sup>−1</sup></span> year-round. In Santiago, we found that <span class="inline-formula"><i>P</i></span>(O<span class="inline-formula"><sub>3</sub></span>) is 23–50 ppbv h<span class="inline-formula"><sup>−1</sup></span> in the ozone season (austral summer). Although the <span class="inline-formula"><i>P</i></span>(O<span class="inline-formula"><sub>3</sub></span>) magnitudes were found to be comparable, Santiago has a well-established ozone season, unlike Quito where concentrations are lower. From sensitivity experiments, alkenes and aromatics contribute 50 % to <span class="inline-formula"><i>P</i></span>(O<span class="inline-formula"><sub>3</sub></span>) in Santiago and could reach 70 %–90 % in Quito (noon and afternoon). Aldehydes and ketones contribute 30 %–40 % in Santiago and about 20 % in Quito (noon and afternoon). We estimate the isoprene contribution to be 20 % in Santiago and 10 % in Quito. VOC reduction experiments generally lowered <span class="inline-formula"><i>P</i></span>(O<span class="inline-formula"><sub>3</sub></span>) in both cities. In Santiago, NO<span class="inline-formula"><sub><i>x</i></sub></span> reductions increased the morning <span class="inline-formula"><i>P</i></span>(O<span class="inline-formula"><sub>3</sub></span>).</p> |
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| ISSN: | 1680-7316 1680-7324 |