Impacts of meteorology and emissions on summertime surface ozone increases over central eastern China between 2003 and 2015

• Main Authors: L. Sun, L. Xue, Y. Wang, L. Li, J. Lin, R. Ni, Y. Yan, L. Chen, J. Li, Q. Zhang, W. Wang
• Format: Article
• Language: English
• Published: Copernicus Publications 2019-02-01
• Series: Atmospheric Chemistry and Physics
• Online Access: https://www.atmos-chem-phys.net/19/1455/2019/acp-19-1455-2019.pdf
• ISSN: 1680-7316; 1680-7324

<p>Recent studies have shown that surface ozone (<span class="inline-formula">O₃</span>) concentrations over central eastern China (CEC) have increased significantly during the past decade. We quantified the effects of changes in meteorological conditions and <span class="inline-formula">O₃</span> precursor emissions on surface <span class="inline-formula">O₃</span> levels over CEC between July 2003 and July 2015 using the GEOS-Chem model. The simulated monthly mean maximum daily 8&thinsp;h average <span class="inline-formula">O₃</span> concentration (MDA8 <span class="inline-formula">O₃</span>) in July increased by approximately 13.6&thinsp;%, from <span class="inline-formula">65.5±7.9</span>&thinsp;ppbv (2003) to <span class="inline-formula">74.4±8.7</span>&thinsp;ppbv (2015), comparable to the observed results. The change in meteorology led to an increase in MDA8 <span class="inline-formula">O₃</span> of <span class="inline-formula">5.8±3.9</span>&thinsp;ppbv over the central part of CEC, in contrast to a decrease of about <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">0.8</mn><mo>±</mo><mn mathvariant="normal">3.5</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="52pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="a675ffef291b8664a49cd32b08a8dde5"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-19-1455-2019-ie00001.svg" width="52pt" height="10pt" src="acp-19-1455-2019-ie00001.png"/></svg:svg></span></span>&thinsp;ppbv over the eastern part of the region. In comparison, the MDA8 <span class="inline-formula">O₃</span> over the central and eastern parts of CEC increased by <span class="inline-formula">3.5±1.4</span> and <span class="inline-formula">5.6±1.8</span>&thinsp;ppbv due to the increased emissions. The increase in averaged <span class="inline-formula">O₃</span> in the CEC region resulting from the emission increase (<span class="inline-formula">4.0±1.9</span>&thinsp;ppbv) was higher than that caused by meteorological changes (<span class="inline-formula">3.1±4.9</span>&thinsp;ppbv) relative to the 2003 standard simulation, while the regions with larger <span class="inline-formula">O₃</span> increases showed a higher sensitivity to meteorological conditions than to emission changes. Sensitivity tests indicate that increased levels of anthropogenic non-methane volatile organic compounds (NMVOCs) dominate the <span class="inline-formula">O₃</span> increase over the eastern part of CEC, and anthropogenic nitrogen oxides (<span class="inline-formula">NO_<i>x</i></span>) mainly increase MDA8 <span class="inline-formula">O₃</span> over the central and western parts and decrease <span class="inline-formula">O₃</span> in a few urban areas in the eastern part. Budget analysis showed that net photochemical production and meteorological conditions (transport in particular) are two important factors that influence <span class="inline-formula">O₃</span> levels over the CEC. The results of this study suggest a need to further assess the effectiveness of control strategies for <span class="inline-formula">O₃</span> pollution in the context of regional meteorology and anthropogenic emission changes.</p>