Zhang Yuxiang, Bo Haixu, Jiang Zhe, Wang Yu, Fu Yunfei, Cao Bingwei, Wang Xuewen, Chen Jiaqi, Li Rui
School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China.
Jiangxi Ecological Environment Monitoring Center, Nanchang 330000, China.
Natl Sci Rev. 2021 Apr 9;8(11):nwab061. doi: 10.1093/nsr/nwab061. eCollection 2021 Nov.
In early 2020, unprecedented lockdowns and travel bans were implemented in Chinese mainland to fight COVID-19, which led to a large reduction in anthropogenic emissions. This provided a unique opportunity to isolate the effects from emission and meteorology on tropospheric nitrogen dioxide (NO). Comparing the atmospheric NO in 2020 with that in 2017, we found the changes of emission have led to a 49.3 ± 23.5% reduction, which was ∼12% more than satellite-observed reduction of 37.8 ± 16.3%. The discrepancy was mainly a result of changes of meteorology, which have contributed to an 8.1 ± 14.2% increase of NO. We also revealed that the emission-induced reduction of NO has significantly negative correlations to human mobility, particularly that inside the city. The intra-city migration index derived from Baidu Location-Based-Service can explain 40.4% ± 17.7% variance of the emission-induced reduction of NO in 29 megacities, each of which has a population of over 8 million in Chinese mainland.
2020年初，中国大陆实施了前所未有的封锁和旅行禁令以抗击新冠疫情，这导致人为排放量大幅减少。这提供了一个独特的机会来分离排放和气象因素对对流层二氧化氮（NO）的影响。通过比较2020年与2017年的大气NO情况，我们发现排放变化导致了49.3±23.5%的减少，这比卫星观测到的37.8±16.3%的减少幅度高出约12%。这种差异主要是气象变化的结果，气象变化导致NO增加了8.1±14.2%。我们还发现，排放导致的NO减少与人类流动性显著负相关，尤其是城市内部的人类流动性。源自百度基于位置服务的城市内部迁移指数可以解释中国大陆29个人口超过800万的大城市中，排放导致的NO减少量变化的40.4%±17.7%。
