[A-AS12] 大気化学

[AAS12-05] 東アジアの対流圏二酸化窒素濃度、10年前のレベルに回復

*入江 仁士¹、武藤 拓也¹、板橋 秀一²、黒川 純一³、鵜野 伊津志⁴ (1.千葉大学、2.電力中央研究所、3.アジア大気汚染研究センター、4.九州大学)

キーワード：NO2、トレンド解析、東アジア、OMI

Long-term (2005-2015) tropospheric nitrogen dioxide (NO₂) column data recorded by the satellite-borne Ozone Monitoring Instrument (OMI) in East Asia were analyzed to investigate annual trends quantitatively and their potential causes. We found an evident decrease in the NO2 level over China after 2011 and then a return to the 2005 level in 2015. The grid-basis trend analysis implies that the rapid decrease occurred on a provincial or larger spatial scale and was likely due to a nationwide action such as the widespread use of denitrification units. Other prominent features were seen in Japan. Despite a significant substitution from nuclear to thermal power after 2011 as a consequence of a massive earthquake off the Pacific coast of northern Japan, the NO₂ level continued to decrease for both periods (2005-2011 and 2011-2015). The decrease contributed to a return to the decade-ago level of tropospheric NO₂ pollution in East Asia.