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Journal Article Ppublish 20 citations

PubMed: 36275858 DOI: 10.1029/2022jd036926

How have Divergent Global Emission Trends Influenced Long-range Transported Ozone to North America?

J Geophys Res Atmos 127(16):0

Authors: Rohit Mathur, Daiwen Kang, Sergey L Napelenok, Jia Xing, Christian Hogrefe, Golam Sarwar, Syuichi Itahashi, Barron H Henderson

Affiliations

  • Center for Environmental Measurement and Modeling, Office of Research and Development, U.S. Environmental Protection Agency, RTP, NC, USA.
  • Tsinghua University, Beijing, China.
  • Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), Japan.
  • Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, RTP, NC, USA.

Abstract

Several locations across the United States in non-compliance with the national standard for ground-level ozone (O 3) are thought to have sizeable influences from distant extra-regional emission sources or natural stratospheric O 3, which complicates design of local emission control measures. To quantify the amount of long-range transported O 3 (LRT O 3), its origin, and change over time, we conduct and analyze detailed sensitivity calculations characterizing the response of O 3 to emissions from different source regions across the Northern Hemisphere in conjunction with multi-decadal simulations of tropospheric O 3 distributions and changes. Model calculations show that the amount of O 3 at any location attributable to sources outside North America varies both spatially and seasonally. On a seasonal-mean basis, during 1990-2010, LRT O 3 attributable to international sources steadily increased by 0.06-0.2 ppb yr -1 at locations across the United States and arose from superposition of unequal and contrasting trends in individual source-region contributions, which help inform attribution of the trend evident in O 3 measurements. Contributions of emissions from Europe steadily declined through 2010, while those from Asian emissions increased and remained dominant. Steadily rising NO x emissions from international shipping resulted in increasing contributions to LRT O 3, comparable to those from Asian emissions in recent years. Central American emissions contribute a significant fraction of LRT O 3 in southwestern United States. In addition to the LRT O 3 attributable to emissions outside of North America, background O 3 across the continental United States is comprised of a sizeable and spatially variable fraction that is of stratospheric origin (29-78%).

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