日本地球惑星科学連合2023年大会

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セッション記号 A (大気水圏科学) » A-AS 大気科学・気象学・大気環境

[A-AS07] 大気化学

2023年5月23日(火) 10:45 〜 12:15 展示場特設会場 (1) (幕張メッセ国際展示場)

コンビーナ:坂本 陽介(京都大学大学院地球環境学堂)、内田 里沙(一般財団法人 日本自動車研究所)、石戸谷 重之(産業技術総合研究所)、岩本 洋子(広島大学大学院統合生命科学研究科)、座長:坂本 陽介(京都大学大学院地球環境学堂)

11:45 〜 12:00

[AAS07-24] Analysis of the COVID-19 influence on an air quality in urban cities in Japan with multiple satellite and ground-based measurements

*藤縄 環1猪俣 敏1杉田 考史1池田 恒平1谷本 浩志1 (1.国立環境研究所)

キーワード:COVID-19、大気質汚染、リモートセンシング、地上観測

Nitrogen dioxide (NO2) is one of the major air pollutants and is harmful to human health. It is mainly emitted from anthropogenic sources (e.g., power plants and vehicles) and play a key role in the photochemical reaction of tropospheric ozone. Therefore, ambient NO2 concentrations are monitored by a variety of instruments at ground-based, airborne, and satellite platforms. The coronavirus disease 2019 (COVID-19) has spread worldwide from December 2019 and it derived severe lockdowns in many cities of the world. Due to these lockdowns, human activities including transports, recreations and energy consumption were drastically reduced, resulting in dramatic decline (26~67%) in the tropospheric NO2 level, especially in megacities. (Liu et al., 2020; Cooper et al., 2022). For Tokyo in Japan, several previous works revealed NO2 decline up to about 50% using in-situ and satellite observations (Ghahremanloo et al., 2020; Ma and Kang, 2020; Fu et al., 2020; Itahashi, 2022; Damiani et al., 2022), though the lockdown was not strictly implemented as in the other countries (i.e., non-legal movement restriction). However, there is no report to link the decline of NO2 specifically to that of the human activity in Japan. In this study, we analyzed ground-based in-situ data and satellite observations with the great focus on Japan’s urban cities and found that the decline of NO2 and related species due to the COVID-19-driven movement restriction in the region including the Tokyo metropolitan area. The comparison of the tropospheric NO2 vertical column densities (VCD) in March and April between 2019 and 2020 shows a 30-40% decline in the TROPOMI (TROPOspheric Monitoring Instrument) NO2 tropospheric column amounts. Tropospheric NO2 VCD observed from OMI (Ozone Monitoring Instrument) shows a similar declining trend of NO2, though a bias of about 0.4 × 1016 molec. cm-2 can be seen against the TROPOMI data. Given the instrumental bias of 0.31 × 1016 molec. cm-2 between OMI and TROPOMI (Wang et al., 2020), the bias derived from our analysis is in reasonable agreement with the previous work, and thus, the decline of the NO2 VCD in March and April in 2020 is independent from the year-to-year factors but by the reduced emissions driven by the movement restriction.