Different atmospheric O3 chemical environment in industrial regions of China, 2016: implications for emission control strategies and impacts on the globe in the future
Authors: Liu Zhenze , M. Doherty Ruth , Wild Oliver , M. O’Connor Fiona 
Published: March 2020

&lt;p&gt;Surface ozone (O&lt;sub&gt;3&lt;/sub&gt;) pollution became the main cause of atmospheric pollution over industrial regions in China since 2013, due to the effective mitigation of fine particulate matter (PM&lt;sub&gt;2.5&lt;/sub&gt;) by stringent emission controls by Air Pollution Prevention and Control Action Plan (APPCAP). O&lt;sub&gt;3&lt;/sub&gt;, as a secondary photochemical pollutant, poses a challenge to control due to its non-linear chemical relationship to precursors &amp;#8211; nitrogen oxides (NO&lt;sub&gt;x&lt;/sub&gt;), carbon monoxide (CO) and volatile organic compounds (VOCs).&lt;/p&gt;&lt;p&gt;We hence investigated the differences of atmospheric chemistry environment in the main industrial regions with high emissions &amp;#8211; North China Plain (NCP), Yangtze River Delta (YRD), Pearl River Delta (PRD) and Chongqing - in summer 2016, China by using a global climate-chemistry model, based on United Kingdom Chemistry and Aerosol (UKCA). Anthropogenic Multi-resolution Emission Inventory for China (MEIC) 2013 and Hemispheric Transport of Air Pollution (HTAP) emissions 2010 for the rest of globe were used but scaled to 2016 regionally and nationally separately. In addition, we improved the gas-phase chemistry scheme by adding more highly reactive VOC tracers to better simulate regional pollution. Diurnal cycles of O&lt;sub&gt;3&lt;/sub&gt; and NO&lt;sub&gt;x&lt;/sub&gt; have been evaluated and the results show very good model-observation comparisons after modifying the gas-phase chemistry scheme. Radical (OH, RO&lt;sub&gt;2&lt;/sub&gt; and HO&lt;sub&gt;2&lt;/sub&gt;), NO&lt;sub&gt;x&lt;/sub&gt; and VOC concentrations have also been examined. O&lt;sub&gt;3&lt;/sub&gt; production rates and budgets calculated based on these show the highest production rate in YRD and the lowest in PRD due to different NO&lt;sub&gt;x&lt;/sub&gt; and VOC concentration levels.&lt;/p&gt;&lt;p&gt;To investigate the O&lt;sub&gt;3 &lt;/sub&gt;sensitivity &amp;#8212; VOC limited or NO&lt;sub&gt;x&lt;/sub&gt; limited, we quantified the O&lt;sub&gt;3&lt;/sub&gt; response to VOCs and NO&lt;sub&gt;x&lt;/sub&gt; in total 64 scenarios by scaling NO&lt;sub&gt;x &lt;/sub&gt;and VOCs emissions. O&lt;sub&gt;3&lt;/sub&gt; isopleths suggest that most regions are VOC limited, but the sensitivities vary. O&lt;sub&gt;3&lt;/sub&gt; in YRD is more sensitive to NO&lt;sub&gt;x&lt;/sub&gt; emission change but PRD can be effectively controlled by decreasing VOC emissions. The ratio of H&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; to HNO&lt;sub&gt;3&lt;/sub&gt; is applied to provide a quick examination method of O&lt;sub&gt;3&lt;/sub&gt; sensitivity. The contribution of O&lt;sub&gt;3&lt;/sub&gt; from China to the global O&lt;sub&gt;3&lt;/sub&gt; burden compared with other continents has also been quantified. The results show that the relatively higher O&lt;sub&gt;3&lt;/sub&gt; concentration in Asia is mainly contributed by China, and O&lt;sub&gt;3&lt;/sub&gt; becomes more sensitive to VOCs. The model allows us to provide a quantitative assessment of different emission controls on mitigating O&lt;sub&gt;3&lt;/sub&gt; over China and the impacts of Chinese emissions on the global O&lt;sub&gt;3&lt;/sub&gt; burden.&lt;/p&gt;