Temporal variations and trend of ground-level ozone based on long-term measurements in Windsor, Canada
<p>This study investigates temporal variations and long-term (1996–2015) trends of ground-level <span class="inline-formula">O<sub>3</sub></span> (ozone) and its precursors, <span class="inline-formula">NO<sub><i>x</i></sub...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-06-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/19/7335/2019/acp-19-7335-2019.pdf |
| Summary: | <p>This study investigates temporal variations and long-term (1996–2015) trends
of ground-level <span class="inline-formula">O<sub>3</sub></span> (ozone) and its precursors, <span class="inline-formula">NO<sub><i>x</i></sub></span> (nitrogen
oxides),
and volatile organic compounds in Windsor, Ontario, Canada. During the
20-year study period, <span class="inline-formula">NO<sub><i>x</i></sub></span>, non-methane hydrocarbon concentrations, and ozone
formation potential decreased significantly by 58 %, 61 %, and 73 %,
respectively, while <span class="inline-formula">O<sub>3</sub></span> concentrations increased by 33 % (20.3 ppb in
1996 vs. 27 ppb in 2015). Our analysis revealed that the increased annual
<span class="inline-formula">O<sub>3</sub></span> concentrations in Windsor were due to (1) decreased <span class="inline-formula">O<sub>3</sub></span>
titration (by 50 % between 1996 and 2015) owing to declining nitric
oxide concentrations, which is suggested by a slightly decreasing trend of
annual mean total <span class="inline-formula">O<sub>3</sub></span> concentrations after the titration effect is
removed, (2) reduced local photochemical production of <span class="inline-formula">O<sub>3</sub></span> because of
dwindling precursor emissions, and (3) an increased background <span class="inline-formula">O<sub>3</sub></span> level
that has a greater impact on the low-to-median concentrations. The net effect of
those factors is decreasing peak <span class="inline-formula">O<sub>3</sub></span> levels during the smog season from
May to September but an overall increasing trend of annual means. These
results indicate that the emission control measures are effective in
reducing peak ozone concentrations. However, challenges in lowering annual
<span class="inline-formula">O<sub>3</sub></span> levels call for long-term collaborative efforts in the region and
around the globe.</p> |
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| ISSN: | 1680-7316 1680-7324 |