Seasonality and reduced nitric oxide titration dominated ozone increase during COVID-19 lockdown in eastern China
Abstract With improving PM2.5 air quality, the tropospheric ozone (O3) has become the top issue of China’s air pollution control. Here, we combine comprehensive observational data analysis with models to unveil the contributions of different processes and precursors to the change of O3 during COVID-...
| Main Authors: | , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2022-03-01
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| Series: | npj Climate and Atmospheric Science |
| Online Access: | https://doi.org/10.1038/s41612-022-00249-3 |
| _version_ | 1811273042954813440 |
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| author | Hongli Wang Cheng Huang Wei Tao Yaqin Gao Siwen Wang Shengao Jing Wenjie Wang Rusha Yan Qian Wang Jingyu An Junjie Tian Qingyao Hu Shengrong Lou Ulrich Pöschl Yafang Cheng Hang Su |
| author_facet | Hongli Wang Cheng Huang Wei Tao Yaqin Gao Siwen Wang Shengao Jing Wenjie Wang Rusha Yan Qian Wang Jingyu An Junjie Tian Qingyao Hu Shengrong Lou Ulrich Pöschl Yafang Cheng Hang Su |
| author_sort | Hongli Wang |
| collection | DOAJ |
| description | Abstract With improving PM2.5 air quality, the tropospheric ozone (O3) has become the top issue of China’s air pollution control. Here, we combine comprehensive observational data analysis with models to unveil the contributions of different processes and precursors to the change of O3 during COVID-19 lockdown in the Yangtze River Delta (YRD), one of the most urbanized megacity regions of eastern China. Despite a 44 to 47% reduction in volatile organic compounds (VOCs) and nitrogen oxides (NOx) emissions, maximum daily 8-h average (MDA8) ozone concentrations increase from 28 ppbv in pre-lockdown to 43 ppbv in lockdown period. We reproduce this transition with the WRF-Chem model, which shows that ~80% of the increase in MDA8 is due to meteorological factors (seasonal variation and radiation), and ~20% is due to emission reduction. We find that daytime photochemistry does not lead to an increase but rather a decrease of daytime O3 production during the lockdown. However, the reduced O3 production is overwhelmed by the weakened nitric oxide (NO) titration resulting in a net increase of O3 concentration. Although the emission reduction increases O3 concentration, it leads to a decrease in the Ox (O3 + NO2) concentration, suggesting reduced atmospheric oxidation capacity on a regional scale. The dominant effect of NO titration demonstrates the importance of prioritizing VOCs reduction, especially from solvent usage and the petrochemical industry with high emission ratios of VOCs/NOx. |
| first_indexed | 2024-04-12T22:50:59Z |
| format | Article |
| id | doaj.art-1588093f069146b5b734b4be123cec6d |
| institution | Directory Open Access Journal |
| issn | 2397-3722 |
| language | English |
| last_indexed | 2024-04-12T22:50:59Z |
| publishDate | 2022-03-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | npj Climate and Atmospheric Science |
| spelling | doaj.art-1588093f069146b5b734b4be123cec6d2022-12-22T03:13:20ZengNature Portfolionpj Climate and Atmospheric Science2397-37222022-03-01511710.1038/s41612-022-00249-3Seasonality and reduced nitric oxide titration dominated ozone increase during COVID-19 lockdown in eastern ChinaHongli Wang0Cheng Huang1Wei Tao2Yaqin Gao3Siwen Wang4Shengao Jing5Wenjie Wang6Rusha Yan7Qian Wang8Jingyu An9Junjie Tian10Qingyao Hu11Shengrong Lou12Ulrich Pöschl13Yafang Cheng14Hang Su15State Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental SciencesState Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental SciencesMultiphase Chemistry Department, Max Planck Institute for ChemistryState Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental SciencesMultiphase Chemistry Department, Max Planck Institute for ChemistryState Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental SciencesMultiphase Chemistry Department, Max Planck Institute for ChemistryState Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental SciencesState Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental SciencesState Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental SciencesState Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental SciencesState Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental SciencesState Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental SciencesMultiphase Chemistry Department, Max Planck Institute for ChemistryMinerva Research Group, Max Planck Institute for ChemistryState Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental SciencesAbstract With improving PM2.5 air quality, the tropospheric ozone (O3) has become the top issue of China’s air pollution control. Here, we combine comprehensive observational data analysis with models to unveil the contributions of different processes and precursors to the change of O3 during COVID-19 lockdown in the Yangtze River Delta (YRD), one of the most urbanized megacity regions of eastern China. Despite a 44 to 47% reduction in volatile organic compounds (VOCs) and nitrogen oxides (NOx) emissions, maximum daily 8-h average (MDA8) ozone concentrations increase from 28 ppbv in pre-lockdown to 43 ppbv in lockdown period. We reproduce this transition with the WRF-Chem model, which shows that ~80% of the increase in MDA8 is due to meteorological factors (seasonal variation and radiation), and ~20% is due to emission reduction. We find that daytime photochemistry does not lead to an increase but rather a decrease of daytime O3 production during the lockdown. However, the reduced O3 production is overwhelmed by the weakened nitric oxide (NO) titration resulting in a net increase of O3 concentration. Although the emission reduction increases O3 concentration, it leads to a decrease in the Ox (O3 + NO2) concentration, suggesting reduced atmospheric oxidation capacity on a regional scale. The dominant effect of NO titration demonstrates the importance of prioritizing VOCs reduction, especially from solvent usage and the petrochemical industry with high emission ratios of VOCs/NOx.https://doi.org/10.1038/s41612-022-00249-3 |
| spellingShingle | Hongli Wang Cheng Huang Wei Tao Yaqin Gao Siwen Wang Shengao Jing Wenjie Wang Rusha Yan Qian Wang Jingyu An Junjie Tian Qingyao Hu Shengrong Lou Ulrich Pöschl Yafang Cheng Hang Su Seasonality and reduced nitric oxide titration dominated ozone increase during COVID-19 lockdown in eastern China npj Climate and Atmospheric Science |
| title | Seasonality and reduced nitric oxide titration dominated ozone increase during COVID-19 lockdown in eastern China |
| title_full | Seasonality and reduced nitric oxide titration dominated ozone increase during COVID-19 lockdown in eastern China |
| title_fullStr | Seasonality and reduced nitric oxide titration dominated ozone increase during COVID-19 lockdown in eastern China |
| title_full_unstemmed | Seasonality and reduced nitric oxide titration dominated ozone increase during COVID-19 lockdown in eastern China |
| title_short | Seasonality and reduced nitric oxide titration dominated ozone increase during COVID-19 lockdown in eastern China |
| title_sort | seasonality and reduced nitric oxide titration dominated ozone increase during covid 19 lockdown in eastern china |
| url | https://doi.org/10.1038/s41612-022-00249-3 |
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