Preprints
https://doi.org/10.5194/acp-2022-110
https://doi.org/10.5194/acp-2022-110
 
07 Apr 2022
07 Apr 2022
Status: this preprint is currently under review for the journal ACP.

Peculiar COVID-19 effects in the Greater Tokyo Area revealed by spatiotemporal variabilities of tropospheric gases and light-absorbing aerosols

Alessandro Damiani1, Hitoshi Irie1, Dmitry Belikov1, Shuei Kaizuka1, Hossain Mohammed Syedul Hoque2, and Raul R. Cordero3 Alessandro Damiani et al.
  • 1Center for Environmental Remote Sensing (CEReS), Chiba University, Chiba, 2638522, Japan
  • 2Graduate School of Environmental Studies, Nagoya University, Nagoya, 4640064, Japan
  • 3Department of Physics, Universidad de Santiago de Chile, Santiago, 3363, Chile

Abstract. This study investigated the spatiotemporal variabilities in nitrogen dioxide (NO2), formaldehyde (HCHO), ozone (O3), and light-absorbing aerosols within the Greater Tokyo Area, Japan, the most populous metropolitan area in the world. The analysis was based on total column, partial column, and in situ observations retrieved from multiple platforms and additional information obtained from reanalysis and box model simulations. This study mainly covers the 2013–2020 period, focusing on 2020, when air quality was influenced by the coronavirus disease 2019 (COVID-19) pandemic. In 2020 overall, NO2 concentrations were reduced by about 10 % annually, with reductions exceeding 40 % in some areas during the pandemic state of emergency. Light-absorbing aerosol levels were also reduced for most of 2020, while smaller fluctuations in HCHO and O3 were observed. Moreover, the degree of weekly cycling of NO2, HCHO, and light-absorbing aerosol levels was significantly enhanced in urban areas during 2020. The latter changes were unprecedented in recent years and potentially related to coincident reduced mobility in Japan, which, in contrast to other countries, was anomalously low on weekends in 2020. This finding suggests that, despite the lack of strict legal restrictions in Japan, widespread adherence to recommendations designed to limit the spread of the pandemic caused modification of common habits, resulting in unique air quality changes.

Alessandro Damiani et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-110', Anonymous Referee #2, 04 May 2022
  • RC2: 'Comment on acp-2022-110', Anonymous Referee #1, 26 May 2022

Alessandro Damiani et al.

Alessandro Damiani et al.

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Short summary
We analyzed the variabilities in tropospheric gases and aerosols within the Greater Tokyo Area, Japan. Beyond highlighting air quality changes caused by the pandemic during the lockdown, we found out that the degree of weekly cycling of most gases and aerosols was enhanced during the whole of 2020. The latter changes were unprecedented in recent years and potentially related to coincident reduced mobility in Japan, which, in contrast to other countries, was anomalously low on weekends in 2020.
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