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Variations of Urban $NO_{2}$ Pollution during the COVID-19 Outbreak and Post-Epidemic Era in China: A Synthesis of Remote Sensing and In Situ Measurements
| Content Provider | MDPI |
|---|---|
| Author | Zhao, Chunhui Zhang, Chengxin Lin, Jinan Wang, Shuntian Liu, Hanyang Wu, Hongyu Liu, Cheng |
| Copyright Year | 2022 |
| Description | Since the COVID-19 outbreak in 2020, China’s air pollution has been significantly affected by control measures on industrial production and human activities. In this study, we analyzed the temporal variations of $NO_{2}$ concentrations during the COVID-19 lockdown and post-epidemic era in 11 Chinese megacities by using satellite and ground-based remote sensing as well as in situ measurements. The average satellite tropospheric vertical column density (TVCD) of $NO_{2}$ by TROPOMI decreased by 39.2–71.93% during the 15 days after Chinese New Year when the lockdown was at its most rigorous compared to that of 2019, while the in situ $NO_{2}$ concentration measured by China National Environmental Monitoring Centre (CNEMC) decreased by 42.53–69.81% for these cities. Such differences between both measurements were further investigated by using ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) remote sensing of $NO_{2}$ vertical profiles. For instance, in Beijing, MAX-DOAS $NO_{2}$ showed a decrease of 14.19% (versus 18.63% by in situ) at the ground surface, and 36.24% (versus 36.25% by satellite) for the total tropospheric column. Thus, vertical discrepancies of atmospheric $NO_{2}$ can largely explain the differences between satellite and in situ $NO_{2}$ variations. In the post-epidemic era of 2021, satellite $NO_{2}$ TVCD and in situ $NO_{2}$ concentrations decreased by 10.42–64.96% and 1.05–34.99% compared to 2019, respectively, possibly related to the reduction of the transportation industry. This study reveals the changes of China’s urban $NO_{2}$ pollution in the post-epidemic era and indicates that COVID-19 had a profound impact on human social activities and industrial production. |
| Starting Page | 419 |
| e-ISSN | 20724292 |
| DOI | 10.3390/rs14020419 |
| Journal | Remote Sensing |
| Issue Number | 2 |
| Volume Number | 14 |
| Language | English |
| Publisher | MDPI |
| Publisher Date | 2022-01-17 |
| Access Restriction | Open |
| Subject Keyword | Remote Sensing Imaging Science No2 Covid-19 Air Pollution Satellite Remote Sensing Tropomi |
| Content Type | Text |
| Resource Type | Article |
