Impacts of compound extreme weather events on ozone in the present and future

Journal Article · 12 July 2018 · Atmospheric Chemistry and Physics (Online)

DOI: https://doi.org/10.5194/ACP-18-9861-2018 · OSTI ID:1463340

Zhang, Junxi ^[1]; Gao, Yang ^[2]; Luo, Kun ^[1]; Leung, L. Ruby ^[3]; Zhang, Yang ^[4]; Wang, Kai ^[4]; Fan, Jianren ^[1]

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1. Zhejiang Univ., Hangzhou (China). State Key Lab. of Clean Energy. Dept. of Energy Engineering
2. Ocean Univ. of China, Qingdao (China). Key Lab. of Marine Environment and Ecology
3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Atmospheric Sciences and Global Change Division
4. North Carolina State Univ., Raleigh, NC (United States). Dept. of Marine, Earth, and Atmospheric Sciences

The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) was used to study the effect of extreme weather events on ozone in the US for historical (2001–2010) and future (2046–2055) periods under the RCP8.5 scenario. During extreme weather events, including heat waves, atmospheric stagnation, and their compound events, ozone concentration is much higher compared to the non-extreme events period. A striking enhancement of effect during compound events is revealed when heat wave and stagnation occur simultaneously as both high temperature and low wind speed promote the production of high ozone concentrations. In regions with high emissions, compound extreme events can shift the high-end tails of the probability density functions (PDFs) of ozone to even higher values to generate extreme ozone episodes. In regions with low emissions, extreme events can still increase high-ozone frequency but the high-end tails of the PDFs are constrained by the low emissions. Despite the large anthropogenic emission reduction projected for the future, compound events increase ozone more than the single events by 10 to 13%, comparable to the present, and high-ozone episodes with a maximum daily 8h average (MDA8) ozone concentration over 70ppbv are not eliminated. Using the CMIP5 multi-model ensemble, the frequency of compound events is found to increase more dominantly compared to the increased frequency of single events in the future over the US, Europe, and China. High-ozone episodes will likely continue in the future due to increases in both frequency and intensity of extreme events, despite reductions in anthropogenic emissions of its precursors. However, the latter could reduce or eliminate extreme ozone episodes; thus improving projections of compound events and their impacts on extreme ozone may better constrain future projections of extreme ozone episodes that have detrimental effects on human health.

• Research Organization: North Carolina State Univ., Raleigh, NC (United States); Ocean Univ. of China, Qingdao (China); Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zhejiang Univ., Hangzhou (China)
• Sponsoring Organization: Environmental Protection Agency (EPA) (United States); Fundamental Research Funds for the Central Universities (China); National Key Project of Ministry of Science and Technology (MOST) (China); National Natural Science Foundation of China (NSFC); USDOE
• Grant/Contract Number: AC05-76RL01830
• OSTI ID: 1463340
• Report Number(s): PNNL-SA--135886
• Journal Information: Atmospheric Chemistry and Physics (Online), Journal Name: Atmospheric Chemistry and Physics (Online) Journal Issue: 13 Vol. 18; ISSN 1680-7324
• Publisher: European Geosciences UnionCopyright Statement
• Country of Publication: United States
• Language: English