Articles | Volume 25, issue 1
https://doi.org/10.5194/acp-25-263-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-25-263-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
09 Jan 2025
Research article |
| 09 Jan 2025
| 09 Jan 2025
Maximum ozone concentrations in the southwestern US and Texas: implications of the growing predominance of the background contribution
David D. Parrish
CORRESPONDING AUTHOR
David.D.Parrish, LLC, 4630 MacArthur Ln, Boulder, Colorado, USA
Ian C. Faloona
Air Quality Research Center, University of California, Davis, Davis, CA, USA
Department of Land, Air, and Water Resources, University of California, Davis, Davis, CA, USA
Richard G. Derwent
rdscientific, Newbury, Berkshire, UK
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David D. Parrish, Richard G. Derwent, Steven T. Turnock, Fiona M. O'Connor, Johannes Staehelin, Susanne E. Bauer, Makoto Deushi, Naga Oshima, Kostas Tsigaridis, Tongwen Wu, and Jie Zhang
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Short summary
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The few ozone measurements made before the 1980s indicate that industrial development increased ozone concentrations by a factor of ~ 2 at northern midlatitudes, which are now larger than at southern midlatitudes. This difference was much smaller, and likely reversed, in the pre-industrial atmosphere. Earth system models find similar increases, but not higher pre-industrial ozone in the south. This disagreement may indicate that modeled natural ozone sources and/or deposition loss are inadequate.
Wenjie Wang, David D. Parrish, Xin Li, Min Shao, Ying Liu, Ziwei Mo, Sihua Lu, Min Hu, Xin Fang, Yusheng Wu, Limin Zeng, and Yuanhang Zhang
Atmos. Chem. Phys., 20, 15617–15633, https://doi.org/10.5194/acp-20-15617-2020, https://doi.org/10.5194/acp-20-15617-2020, 2020
Short summary
Short summary
During the past decade, China has devoted very substantial resources to improving the environment. These efforts have improved atmospheric particulate matter loading, but ambient ozone levels have continued to increase. In this paper we investigate the causes of the increasing ozone concentrations through analysis of a data set that is, to our knowledge, unique: a 12-year data set including ground-level O3, NOx, and VOC precursors collected at an urban site in Beijing.
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Short summary
Observation-based estimates of contributions to maximum ozone (O3) concentrations show that background O3 can exceed the air quality standard of 70 ppb in the southwestern US, precluding standard attainment. Over the past 4 decades, US anthropogenic O3 has decreased by a factor of ~ 6.3, while wildfire contributions have increased, so that the background now dominates maximum concentrations, even in Los Angeles, and the occurrence of maximum O3 has shifted from the eastern to the western US.
Observation-based estimates of contributions to maximum ozone (O3) concentrations show that...
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