| 概要 |
Tropospheric ozone (O_3) is an air pollutant and greenhouse gas and is still a problem in East Asia. O_3 is formed via secondary photochemistry from nitrogen oxide (NO_x) and volatile organic compound... (VOC) precursors. Because of the increase in anthropogenic emissions globally, changes in O_3 concentration over the Northern Hemisphere have been a concern. In this study, using measurements at three remote sites conducted by the Japan Meteorological Agency (JMA), the 30-year (1990s to 2020) long-term trend of background O_3 concentration was analyzed. The results of the fitted curve revealed that background O_3 concentration has changed by within ±0.3 ppbv/year over 30 years. The increasing trend at Ryori (39.03°N, 141.82°E) peaked in 2009 and then decreased, agreeing well with other reports in the mid-latitude zone (40°N-55°N). In contrast, the present study revealed continuous decreasing trends at Minamitorishima (24.28°N, 153.98°E) and Yonagunijima (24.47°N, 123.02°E) at lower latitudes. In addition, the analysis for 2020 clarified that the frequency density shifted to a lower O_3 concentration compared with the dataset for the 1990s to 2019 at all three remote sites in Japan. This suggested that the emission reduction resulting from the COVID-19 pandemic could be a factor causing the decreasing background O_3 concentration.続きを見る
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Mendeley出力
Itahashi_2025_SOLA