Citation:

Mathur, R., D. Kang, S. Napelenok, C. Hogrefe, G. Sarwar, J. Xing, S. Itahashi, AND B. Henderson. Contributions of Source Regions to Changes in Long-Range Transported Ozone to North America during 1990-2010: A Modeling Analysis-Book Chapter. Air Pollution Modeling and Its Application XXVIII. Springer, Heidelberg, Germany, , 107-112, (2023). https://doi.org/10.1007/978-3-031-12786-1_14

Impact/Purpose:

Ambient ozone levels in a region result from contributions from multiple sources including domestic and international anthropogenic precursor emissions as well as natural sources including stratosphere-troposphere exchange, biogenic, lightning, soil, and wildfire, emissions. Pollutants from continental source regions get lofted to the free troposphere and can be subjected to inter-continental transport. Several locations in non-compliance with the National Ambient Air Quality Standard for O3 across the U.S. are thought to have non-negligible and increasing influences from pollution transported long distances and attributable to distant international emissions. Understanding the relative contributions of these international sources, the dominant natural contributions, and the changes in these contributions over time driven by global emission changes, is important for guiding local air quality management.

Description:

As measures to limit the impacts of domestic emissions on surface-level ozone (O3) pollution are implemented, the increasing contributions of O3 pollution transported from other regions become more influential in shaping local O3 levels and confounds design of abatement measures to meet more stringent air quality standards. We investigate the contributions of emission changes from seven source regions, as well as the stratosphere, on the change in tropospheric ozone burden across the Northern Hemisphere and its influence on long-range transport (LRT) of O3 to North America during the 1990-2010 period. Sensitivity calculations conducted with the Hemispheric Community Multiscale Air Quality (HCMAQ) model to estimate the response of O3 to emissions from different source regions across the Northern Hemisphere are combined with simulated changes in O3 due to emission changes during the multi-decadal analysis period to delineate impacts of different source regions in shaping the long-range transported O3 to North America.

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