Articles | Volume 24, issue 11
https://doi.org/10.5194/acp-24-6539-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-24-6539-2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
04 Jun 2024
Research article |
| 04 Jun 2024
| 04 Jun 2024
Impact of weather patterns and meteorological factors on PM2.5 and O3 responses to the COVID-19 lockdown in China
IEK-7: Stratosphere, Institute of Energy and Climate Research, Forschungszentrum Jülich, 52425 Jülich, Germany
Michaela I. Hegglin
CORRESPONDING AUTHOR
IEK-7: Stratosphere, Institute of Energy and Climate Research, Forschungszentrum Jülich, 52425 Jülich, Germany
Department of Meteorology, University of Reading, Reading, RG6 6BX, UK
Yue Yuan
Jining Meteorological Bureau, Shandong 272000, China
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Atmos. Chem. Phys., 26, 13817–13843, https://doi.org/10.5194/acp-26-13817-2026, https://doi.org/10.5194/acp-26-13817-2026, 2026
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This study investigates tropical ozone changes in models and satellite observations to determine how well they agree and whether observations can constrain model projections. At some levels, satellite records disagree significantly on the magnitude of ozone changes. While early and late 21st century trends are correlated across models, suggesting a potential emergent constraint, the spread in observations means they are unable to provide guidance on the credibility of model projections.
Florian Voet, Felix Ploeger, Johannes C. Laube, Laura N. Saunders, Patrick E. Sheese, Attahir Mainika, Peter Preusse, Jens-Uwe Grooß, Kaley A. Walker, Susann Tegtmeier, and Michaela Imelda Hegglin
EGUsphere, https://doi.org/10.5194/egusphere-2026-4647, https://doi.org/10.5194/egusphere-2026-4647, 2026
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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We developed a better way to estimate how long air remains in the upper atmosphere, because satellite estimates can be too noisy to show long-term changes. Using measurements of several gases from a satellite, we found that combining them cuts uncertainty by about half and gives estimates with about 0.3 years of average uncertainty. Results for 2004–2021 show older air in the Northern Hemisphere and younger air in the tropics and Southern Hemisphere, suggesting slower circulation in the north.
Jan Kaumanns, Florian Voet, Felix Ploeger, Peter Preuße, Jörn Ungermann, and Michaela Imelda Hegglin
EGUsphere, https://doi.org/10.5194/egusphere-2026-4183, https://doi.org/10.5194/egusphere-2026-4183, 2026
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Age-of-Air (AoA) denotes the time an air parcel has spent inside the stratosphere and is an important diagnostic quantity for the Brewer Dobson Circulation (BDC). We present a novel approach using neural networks to accurately and robustly derive AoA from inert chemical species with considerable measurement noise even far beyond the training domain. We also present an alternative view of AoA by using autoencoders to derive a model-independent proxy quantity for it and validate its robustness.
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Atmos. Chem. Phys., 26, 8981–8997, https://doi.org/10.5194/acp-26-8981-2026, https://doi.org/10.5194/acp-26-8981-2026, 2026
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Shubhajyoti Roy, Satheesh P. R. Chandran, Suvarna Fadnavis, Vijay Sagar, Michaela I. Hegglin, Rolf Müller, and Prashant Chavan
Atmos. Chem. Phys., 26, 7047–7059, https://doi.org/10.5194/acp-26-7047-2026, https://doi.org/10.5194/acp-26-7047-2026, 2026
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Marta Abalos, Thomas Birner, Andreas Chrysanthou, Sean Davis, Alvaro de la Cámara, Sandip Dhomse, Hella Garny, Michaela I. Hegglin, Daan Hubert, Oksana Ivaniha, James Keeble, Marianna Linz, Daniele Minganti, Jessica Neu, David Plummer, Laura Saunders, Kasturi Shah, Gabriele Stiller, Kleareti Tourpali, Darryn Waugh, Nathan Luke Abraham, Hideharu Akiyoshi, Martyn P. Chipperfield, Patrick Jöckel, Béatrice Josse, Marion Marchand, Patrick Martineau, Olaf Morgenstern, Timofei Sukhodolov, Shingo Watanabe, and Yousuke Yamashita
Atmos. Chem. Phys., 26, 5249–5291, https://doi.org/10.5194/acp-26-5249-2026, https://doi.org/10.5194/acp-26-5249-2026, 2026
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Accurate representation of stratospheric transport in Chemistry-Climate Models is essential for reliable climate projections. This study evaluates three generations of models using observational data and reanalyses, identifying persistent biases and their potential causes. Some biases persist or even worsen in newer models. These findings highlight key limitations and inform efforts to improve models and advance understanding through process-based studies and enhanced observations.
Zhen Yang, Bärbel Vogel, Felix Plöger, Zhixuan Bai, Dan Li, Sabine Griessbach, Lars Hoffmann, Frank G. Wienhold, Elizabeth Asher, Alexandre A. Baron, Katie R. Smith, Troy Thornberry, Jianchun Bian, and Michaela I. Hegglin
Atmos. Chem. Phys., 26, 4749–4769, https://doi.org/10.5194/acp-26-4749-2026, https://doi.org/10.5194/acp-26-4749-2026, 2026
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Balloon measurements over Lhasa, China, combined with satellite guided modelling, tracked aerosol from the 2019 Raikoke eruption through the Asian summer monsoon anticyclone. We find two altitude dependent routes into the anticyclone. It partly blocks transport but also allows entry and mixing, explaining the gradual weakening of the layers. Balloon measurements over Boulder, United States, outside the anticyclone, provide an independent check outside the region.
Liliana Guidetti, Erika Brattich, Simone Ceccherini, Michaela I. Hegglin, Piera Raspollini, Cecilia Tirelli, Nicola Zoppetti, and Ugo Cortesi
Atmos. Meas. Tech., 19, 167–184, https://doi.org/10.5194/amt-19-167-2026, https://doi.org/10.5194/amt-19-167-2026, 2026
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The Complete Data Fusion algorithm is applied to observations from the Michelson Interferometer for Passive Atmospheric Sounding and the Infrared Atmospheric Sounding Interferometer to generate and validate a new ozone dataset against ozone soundings across multiple latitudes. The fusion propagates stratospheric limb information into the troposphere. The dataset shows increased information content and lower uncertainty, improving the study of stratosphere–troposphere ozone intrusions.
Paul Konopka, Felix Ploeger, Francesco D'Amato, Teresa Campos, Marc von Hobe, Shawn B. Honomichl, Peter Hoor, Laura L. Pan, Michelle L. Santee, Silvia Viciani, Kaley A. Walker, and Michaela I. Hegglin
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Patrick Konjari, Christian Rolf, Michaela I. Hegglin, Susanne Rohs, Yun Li, Andreas Zahn, Harald Bönisch, Philippe Nedelec, Martina Krämer, and Andreas Petzold
Atmos. Chem. Phys., 25, 4269–4289, https://doi.org/10.5194/acp-25-4269-2025, https://doi.org/10.5194/acp-25-4269-2025, 2025
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Florian Voet, Felix Ploeger, Johannes Laube, Peter Preusse, Paul Konopka, Jens-Uwe Grooß, Jörn Ungermann, Björn-Martin Sinnhuber, Michael Höpfner, Bernd Funke, Gerald Wetzel, Sören Johansson, Gabriele Stiller, Eric Ray, and Michaela I. Hegglin
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Ziming Wang, Luca Bugliaro, Klaus Gierens, Michaela I. Hegglin, Susanne Rohs, Andreas Petzold, Stefan Kaufmann, and Christiane Voigt
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Upper-tropospheric relative humidity bias in the ERA5 weather model is corrected by 10 % by an artificial neural network using aircraft in-service humidity data and thermodynamic and dynamical variables. The improved skills of the weather model will advance cirrus research, weather forecasts, and measures for contrail reduction.
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Preprint archived
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This study evaluates machine learning (ML) methods to improve subseasonal-to-seasonal (S2S) rainfall forecasts in Senegal during the West African monsoon. Using high-resolution precipitation data and atmospheric-oceanic reanalysis, we show that ML models like ridge regression outperform traditional climate models. These methods enhance prediction accuracy and efficiency, offering valuable tools for climate risk management and water resource planning.
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Our research explored changes in ozone levels in the northwest Pacific region over 30 years, revealing a significant increase in the middle-to-upper troposphere, especially during spring and summer. This rise is influenced by both stratospheric and tropospheric sources, which affect climate and air quality in East Asia. This work underscores the need for continued study to understand underlying mechanisms.
Luis F. Millán, Peter Hoor, Michaela I. Hegglin, Gloria L. Manney, Harald Boenisch, Paul Jeffery, Daniel Kunkel, Irina Petropavlovskikh, Hao Ye, Thierry Leblanc, and Kaley Walker
Atmos. Chem. Phys., 24, 7927–7959, https://doi.org/10.5194/acp-24-7927-2024, https://doi.org/10.5194/acp-24-7927-2024, 2024
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In the Observed Composition Trends And Variability in the UTLS (OCTAV-UTLS) Stratosphere-troposphere Processes And their Role in Climate (SPARC) activity, we have mapped multiplatform ozone datasets into coordinate systems to systematically evaluate the influence of these coordinates on binned climatological variability. This effort unifies the work of studies that focused on individual coordinate system variability. Our goal was to create the most comprehensive assessment of this topic.
Mohamadou A. Diallo, Felix Ploeger, Michaela I. Hegglin, Manfred Ern, Jens-Uwe Grooß, Sergey Khaykin, and Martin Riese
Atmos. Chem. Phys., 22, 14303–14321, https://doi.org/10.5194/acp-22-14303-2022, https://doi.org/10.5194/acp-22-14303-2022, 2022
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The quasi-biennial oacillation disruption events in both 2016 and 2020 decreased lower-stratospheric water vapour and ozone. Differences in the strength and depth of the anomalous lower-stratospheric circulation and ozone are due to differences in tropical upwelling and cold-point temperature induced by lower-stratospheric planetary and gravity wave breaking. The differences in water vapour are due to higher cold-point temperature in 2020 induced by Australian wildfire.
Cited articles
Bei, N., Li, G., Huang, R.-J., Cao, J., Meng, N., Feng, T., Liu, S., Zhang, T., Zhang, Q., and Molina, L. T.: Typical synoptic situations and their impacts on the wintertime air pollution in the Guanzhong basin, China, Atmos. Chem. Phys., 16, 7373–7387, https://doi.org/10.5194/acp-16-7373-2016, 2016.
Chang, Y., Huang, R.-J., Ge, X., Huang, X., Hu, J., Duan, Y., Zou, Z., Liu, X., and Lehmann, M. F.: Puzzling Haze Events in China During the Coronavirus (COVID-19) Shutdown, Geophys. Res. Lett., 47, e2020GL088533, https://doi.org/10.1029/2020GL088533, 2020.
Chen, X., Wang, N., Wang, G., Wang, Z., Chen, H., Cheng, C., Li, M., Zheng, L., Wu, L., and Zhang, Q.: The influence of synoptic weather patterns on spatiotemporal characteristics of ozone pollution across Pearl River Delta of southern China, J. Geophys. Res.-Atmos., 127, e2022JD037121, https://doi.org/10.1029/2022JD037121, 2022.
Dang, R. and Liao, H.: Radiative forcing and health impact of aerosols and ozone in China as the consequence of clean air actions over 2012–2017, Geophys. Res. Lett., 46, 12511–12519, 2019.
Dayan, U. and Levy, I.: Relationship between synoptic-scale atmospheric circulation and ozone concentrations over Israel, J. Geophys. Res.-Atmos., 107, ACL 31-1–ACL 31-12, 2002.
Demuzere, M., Trigo, R. M., Vila-Guerau de Arellano, J., and van Lipzig, N. P. M.: The impact of weather and atmospheric circulation on O3 and PM10 levels at a rural mid-latitude site, Atmos. Chem. Phys., 9, 2695–2714, https://doi.org/10.5194/acp-9-2695-2009, 2009.
Doan, Q.-V., Kusaka, H., Sato, T., and Chen, F.: S-SOM v1.0: a structural self-organizing map algorithm for weather typing, Geosci. Model Dev., 14, 2097–2111, https://doi.org/10.5194/gmd-14-2097-2021, 2021.
Dong, Y., Li, J., Guo, J., Jiang, Z., Chu, Y., Chang, L., Yang, Y., and Liao, H.: The impact of synoptic patterns on summertime ozone pollution in the North China Plain, Sci. Total Environ., 735, 139559, https://doi.org/10.1016/j.scitotenv.2020.139559, 2020.
Feng, Z., Hu, E., Wang, X., Jiang, L., and Liu, X.: Ground-level O3 pollution and its impacts on food crops in China: a review, Environ. Pollut., 199, 42–48, 2015.
Frakes, B. and Yarnal, B.: A procedure for blending manual and correlation-based synoptic classifications, Int. J. Climatol., 17, 1381=-1396, https://doi.org/10.1002/(SICI)1097-0088(19971115)17:13<1381::AID-JOC204>3.0.CO;2-Q, 1997.
Fu, S., Guo, M., Fan, L., Deng, Q., Han, D., Wei, Y., Luo, J., Qin, G., and Cheng, J.: Ozone pollution mitigation in guangxi (south China) driven by meteorology and anthropogenic emissions during the COVID-19 lockdown, Environ. Pollut., 272, 115927, https://doi.org/10.1016/j.envpol.2020.115927, 2021.
Ge, B., Sun, Y., Liu, Y., Dong, H., Ji, D., Jiang, Q., Li, J., and Wang, Z.: Nitrogen dioxide measurement by cavity attenuated phase shift spectroscopy (CAPS) and implications in ozone production efficiency and nitrate formation in Beijing, China, J. Geophys. Res.-Atmos., 118, 9499–9509, 2013.
Han, H., Liu, J., Yuan, H., Jiang, F., Zhu, Y., Wu, Y., Wang, T., and Zhuang, B.: Impacts of synoptic weather patterns and their persistency on free tropospheric carbon monoxide concentrations and outflow in eastern China, J. Geophys. Res.-Atmos., 123, 7024–7046, 2018.
He, G., Pan, Y., and Tanaka, T.: The short-term impacts of COVID-19 lockdown on urban air pollution in China, Nature Sustainability, 3, 1005–1011, https://doi.org/10.1038/s41893-020-0581-y, 2020.
Hegarty, J., Mao, H., and Talbot, R.: Synoptic controls on summertime surface ozone in the northeastern United States, J. Geophys. Res.-Atmos., 112, D14306, https://doi.org/10.1029/2006JD008170, 2007.
Huang, X., Ding, A., Gao, J., Zheng, B., Zhou, D., Qi, X., Tang, R., Wang, J., Ren, C., Nie, W., Chi, X., Xu, Z., Chen, L., Li, Y., Che, F., Pang, N., Wang, H., Tong, D., Qin, W., Cheng, W., Liu, W., Fu, Q., Liu, B., Chai, F., Davis, S. J., Zhang, Q., and He, K.: Enhanced secondary pollution offset reduction of primary emissions during COVID-19 lockdown in China, Nat. Sci. Rev., 8, nwaa137, https://doi.org/10.1093/nsr/nwaa137, 2021.
Huth, R., Beck, C., Philipp, A., Demuzere, M., Ustrnul, Z., Cahynová, M., Kyselý, J., and Tveito, O. E.: Classifications of Atmospheric Circulation Patterns, Ann. N. Y. Acad. Sci., 1146, 105–152, https://doi.org/10.1196/annals.1446.019, 2008.
Jiang, N., Scorgie, Y., Hart, M., Riley, M. L., Crawford, J., Beggs, P. J., Edwards, G. C., Chang, L., Salter, D., and Virgilio, G. D.: Visualising the relationships between synoptic circulation type and air quality in Sydney, a subtropical coastal-basin environment, Int. J. Climatol., 37, 1211–1228, https://doi.org/10.1002/joc.4770, 2017.
Jin, H., Chen, X., Zhong, R., and Liu, M.: Influence and prediction of PM2.5 through multiple environmental variables in China, Sci. Total Environ., 849, 157910, https://doi.org/10.1016/j.scitotenv.2022.157910, 2022.
Knote, C., Tuccella, P., Curci, G., Emmons, L., Orlando, J. J., Madronich, S., Baró, R., Jiménez-Guerrero, P., Luecken, D., and Hogrefe, C.: Influence of the choice of gas-phase mechanism on predictions of key gaseous pollutants during the AQMEII phase-2 intercomparison, Atmos. Environ., 115, 553–568, 2015.
Kohonen, T.: A simple paradigm for the self-organized formation of structured feature maps, Competition and Cooperation in Neural Nets: Proceedings of the US-Japan Joint Seminar, Kyoto, Japan, 15–19 February 1982, Springer, Berlin, Heidelberg, 248–266, ISBN 978-3-540-11574-8, 1982.
Le, T., Wang, Y., Liu, L., Yang, J., Yung, Y. L., Li, G., and Seinfeld, J. H.: Unexpected air pollution with marked emission reductions during the COVID-19 outbreak in China, Science, 369, 702–706, 2020.
Lelieveld, J., Evans, J. S., Fnais, M., Giannadaki, D., and Pozzer, A.: The contribution of outdoor air pollution sources to premature mortality on a global scale, Nature, 525, 367–371, https://doi.org/10.1038/nature15371, 2015.
Lewis, A. B. and Keim, B. D.: A hybrid procedure for classifying synoptic weather types for Louisiana, USA, Int. J. Climatol., 35, 4247–4261, https://doi.org/10.1002/joc.4283, 2015.
Li, H., Cheng, J., Zhang, Q., Zheng, B., Zhang, Y., Zheng, G., and He, K.: Rapid transition in winter aerosol composition in Beijing from 2014 to 2017: response to clean air actions, Atmos. Chem. Phys., 19, 11485–11499, https://doi.org/10.5194/acp-19-11485-2019, 2019.
Li, K., Jacob, D. J., Liao, H., Zhu, J., Shah, V., Shen, L., Bates, K. H., Zhang, Q., and Zhai, S.: A two-pollutant strategy for improving ozone and particulate air quality in China, Nat. Geosci., 12, 906–910, https://doi.org/10.1038/s41561-019-0464-x, 2019.
Li, X., Zhao, B., Zhou, W., Shi, H., Yin, R., Cai, R., Yang, D., Dällenbach, K., Deng, C., Fu, Y., Qiao, X., Wang, L., Liu, Y., Yan, C., Kulmala, M., Zheng, J., Hao, J., Wang, S., and Jiang, J.: Responses of gaseous sulfuric acid and particulate sulfate to reduced SO2 concentration: A perspective from long-term measurements in Beijing, Sci. Total Environ., 721, 137700, https://doi.org/10.1016/j.scitotenv.2020.137700, 2020.
Liao, H., Chang, W., and Yang, Y.: Climatic effects of air pollutants over China: A review, Adv. Atmos. Sci., 32, 115–139, 2015.
Liao, Z., Gao, M., Sun, J., and Fan, S.: The impact of synoptic circulation on air quality and pollution-related human health in the Yangtze River Delta region, Sci. Total Environ., 607–608, 838–846, https://doi.org/10.1016/j.scitotenv.2017.07.031, 2017.
Liu, J., Wang, L., Li, M., Liao, Z., Sun, Y., Song, T., Gao, W., Wang, Y., Li, Y., Ji, D., Hu, B., Kerminen, V.-M., Wang, Y., and Kulmala, M.: Quantifying the impact of synoptic circulation patterns on ozone variability in northern China from April to October 2013–2017, Atmos. Chem. Phys., 19, 14477–14492, https://doi.org/10.5194/acp-19-14477-2019, 2019.
Liu, Y., Wang, T., Stavrakou, T., Elguindi, N., Doumbia, T., Granier, C., Bouarar, I., Gaubert, B., and Brasseur, G. P.: Diverse response of surface ozone to COVID-19 lockdown in China, Sci. Total Environ., 789, 147739, https://doi.org/10.1016/j.scitotenv.2021.147739, 2021.
Lundberg, S. M., Erion, G., Chen, H., DeGrave, A., Prutkin, J. M., Nair, B., Katz, R., Himmelfarb, J., Bansal, N., and Lee, S.-I.: From local explanations to global understanding with explainable AI for trees, Nature Machine Intelligence, 2, 56–67, 2020.
Lv, Z., Wang, X., Deng, F., Ying, Q., Archibald, A. T., Jones, R. L., Ding, Y., Cheng, Y., Fu, M., Liu, Y., Man, H., Xue, Z., He, K., Hao, J., and Liu, H.: Source–Receptor Relationship Revealed by the Halted Traffic and Aggravated Haze in Beijing during the COVID-19 Lockdown, Environ. Sci. Technol., 54, 15660–15670, https://doi.org/10.1021/acs.est.0c04941, 2020.
Ma, T., Duan, F., Ma, Y., Zhang, Q., Xu, Y., Li, W., Zhu, L., and He, K.: Unbalanced emission reductions and adverse meteorological conditions facilitate the formation of secondary pollutants during the COVID-19 lockdown in Beijing, Sci. Total Environ., 838, 155970, https://doi.org/10.1016/j.scitotenv.2022.155970, 2022.
Miao, Y., Guo, J., Liu, S., Liu, H., Li, Z., Zhang, W., and Zhai, P.: Classification of summertime synoptic patterns in Beijing and their associations with boundary layer structure affecting aerosol pollution, Atmos. Chem. Phys., 17, 3097–3110, https://doi.org/10.5194/acp-17-3097-2017, 2017.
Nie, D., Shen, F., Wang, J., Ma, X., Li, Z., Ge, P., Ou, Y., Jiang, Y., Chen, M., and Chen, M.: Changes of air quality and its associated health and economic burden in 31 provincial capital cities in China during COVID-19 pandemic, Atmos. Res., 249, 105328, https://doi.org/10.1016/j.atmosres.2020.105328, 2021.
Pope, R. J., Savage, N. H., Chipperfield, M. P., Ordóñez, C., and Neal, L. S.: The influence of synoptic weather regimes on UK air quality: regional model studies of tropospheric column NO2, Atmos. Chem. Phys., 15, 11201–11215, https://doi.org/10.5194/acp-15-11201-2015, 2015.
Shen, F., Zhang, L., Jiang, L., Tang, M., Gai, X., Chen, M., and Ge, X.: Temporal variations of six ambient criteria air pollutants from 2015 to 2018, their spatial distributions, health risks and relationships with socioeconomic factors during 2018 in China, Environ. Int., 137, 105556, https://doi.org/10.1016/j.envint.2020.105556, 2020.
Shen, F., Hegglin, M. I., Luo, Y., Yuan, Y., Wang, B., Flemming, J., Wang, J., Zhang, Y., Chen, M., Yang, Q., and Ge, X.: Disentangling drivers of air pollutant and health risk changes during the COVID-19 lockdown in China, npj Clim. Atmos. Sci., 5, 54, https://doi.org/10.1038/s41612-022-00276-0, 2022.
Shu, L., Wang, T., Han, H., Xie, M., Chen, P., Li, M., and Wu, H.: Summertime ozone pollution in the Yangtze River Delta of eastern China during 2013–2017: Synoptic impacts and source apportionment, Environ. Pollut., 257, 113631, https://doi.org/10.1016/j.envpol.2019.113631, 2020.
Su, T., Li, Z., Zheng, Y., Luan, Q., and Guo, J.: Abnormally Shallow Boundary Layer Associated With Severe Air Pollution During the COVID-19 Lockdown in China, Geophys. Res. Lett., 47, e2020GL090041, https://doi.org/10.1029/2020GL090041, 2020.
Sun, Y., Lei, L., Zhou, W., Chen, C., He, Y., Sun, J., Li, Z., Xu, W., Wang, Q., Ji, D., Fu, P., Wang, Z., and Worsnop, D. R.: A chemical cocktail during the COVID-19 outbreak in Beijing, China: Insights from six-year aerosol particle composition measurements during the Chinese New Year holiday, Sci. Total Environ., 742, 140739, https://doi.org/10.1016/j.scitotenv.2020.140739, 2020.
Wang, H., Huang, C., Tao, W., Gao, Y., Wang, S., Jing, S., Wang, W., Yan, R., Wang, Q., and An, J.: Seasonality and reduced nitric oxide titration dominated ozone increase during COVID-19 lockdown in eastern China, npj Clim. Atmos. Sci., 5, 24, https://doi.org/10.1038/s41612-022-00249-3, 2022.
Wang, J., Lei, Y., Chen, Y., Wu, Y., Ge, X., Shen, F., Zhang, J., Ye, J., Nie, D., Zhao, X., and Chen, M.: Comparison of air pollutants and their health effects in two developed regions in China during the COVID-19 pandemic, J. Environ. Manage., 287, 112296, https://doi.org/10.1016/j.jenvman.2021.112296, 2021.
Wang, P., Chen, K., Zhu, S., Wang, P., and Zhang, H.: Severe air pollution events not avoided by reduced anthropogenic activities during COVID-19 outbreak, Resour. Conserv. Recy., 158, 104814, https://doi.org/10.1016/j.resconrec.2020.104814, 2020.
Wang, X., Manning, W., Feng, Z., and Zhu, Y.: Ground-level ozone in China: distribution and effects on crop yields, Environ. Pollut., 147, 394–400, 2007.
Wang, Z. and Bovik, A. C.: Mean squared error: Love it or leave it? A new look at signal fidelity measures, IEEE Signal Proc. Mag., 26, 98–117, 2009.
Wang, Z., Bovik, A. C., Sheikh, H. R., and Simoncelli, E. P.: Image quality assessment: from error visibility to structural similarity, IEEE T. Image Process., 13, 600–612, https://doi.org/10.1109/TIP.2003.819861, 2004.
Weng, X., Forster, G. L., and Nowack, P.: A machine learning approach to quantify meteorological drivers of ozone pollution in China from 2015 to 2019, Atmos. Chem. Phys., 22, 8385–8402, https://doi.org/10.5194/acp-22-8385-2022, 2022.
Weng, X., Li, J., Forster, G. L., and Nowack, P.: Large modeling uncertainty in projecting decadal surface ozone changes over city clusters of China, Geophys. Res. Lett., 50, e2023GL103241, https://doi.org/10.1029/2023GL103241, 2023.
WHO (World Health Organisation): COVID-19 deaths, WHO COVID-19 Dashboard, World Health Organisation, https://data.who.int/dashboards/covid19/deaths?n=o (last access: 28 May 2024), 2024.
Xiao, Q., Chang, H. H., Geng, G., and Liu, Y.: An ensemble machine-learning model to predict historical PM2.5 concentrations in China from satellite data, Environ. Sci. Technol., 52, 13260–13269, 2018.
Xu, J., Ge, X., Zhang, X., Zhao, W., Zhang, R., and Zhang, Y.: COVID-19 Impact on the Concentration and Composition of Submicron Particulate Matter in a Typical City of Northwest China, Geophys. Res. Lett., 47, e2020GL089035, https://doi.org/10.1029/2020GL089035, 2020.
Zhan, C.-C., Xie, M., Fang, D.-X., Wang, T.-J., Wu, Z., Lu, H., Li, M.-M., Chen, P.-L., Zhuang, B.-L., and Li, S.: Synoptic weather patterns and their impacts on regional particle pollution in the city cluster of the Sichuan Basin, China, Atmos. Environ., 208, 34–47, 2019.
Zhang, M., Wu, D., and Xue, R.: Hourly prediction of PM2.5 concentration in Beijing based on Bi-LSTM neural network, Multimed. Tools Appl., 80, 24455–24468, 2021.
Zhang, Y., Mao, H., Ding, A., Zhou, D., and Fu, C.: Impact of synoptic weather patterns on spatio-temporal variation in surface O3 levels in Hong Kong during 1999–2011, Atmos. Environ., 73, 41–50, 2013.
Zhang, Y., Ding, A., Mao, H., Nie, W., Zhou, D., Liu, L., Huang, X., and Fu, C.: Impact of synoptic weather patterns and inter-decadal climate variability on air quality in the North China Plain during 1980–2013, Atmos. Environ., 124, 119–128, 2016.
Zheng, M., Yan, C., Wang, S., He, K., and Zhang, Y.: Understanding PM2.5 sources in China: challenges and perspectives, Nat. Sci. Rev., 4, 801–803, https://doi.org/10.1093/nsr/nwx129, 2017.
Short summary
We attempt to use a novel structural self-organising map and machine learning models to identify a weather system and quantify the importance of each meteorological factor in driving the unexpected PM2.5 and O3 changes under the specific weather system during the COVID-19 lockdown in China. The result highlights that temperature under the double-centre high-pressure system plays the most crucial role in abnormal events.
We attempt to use a novel structural self-organising map and machine learning models to identify...
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