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| 1.
論文（リポジトリ） |
論文（リポジトリ）
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Itahashi, Syuichi ; Hatakeyama, Shiro ; Shimada, Kojiro ; Takami, Akinori
概要:
Intensive observation campaigns approximately 1 week long were conducted periodically from March 2010 to November 2015 a
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t Cape Hedo, Okinawa, Japan. The maximum daily mean sulfate aerosol (SO_4^<2->) concentrations surpassed 15 µg m^<–3> in spring 2012. In this study, source apportionment for these high concentrations was conducted using an air quality model with the tagged tracer method, and the main source was identified as volcanoes in March and as anthropogenic emissions from China in April. In March, the prevailing northerly wind transported a volcanic SO_2 plume with a low conversion ratio to Cape Hedo. The impacts of 15 volcanoes in Japan were estimated, and a substantial impact from Sakurajima, which accounted for more SO_2 than anthropogenic emissions from Japan, was found. Because the model had difficulty capturing the highest concentration, three sensitivity simulations were performed to consider the uncertainty of the volcanic SO_2 emission amounts and injection heights, revealing the importance of the injection height in addition to the SO_2 emission amount. Throughout April, contributions from anthropogenic emissions from China were found; hence, this source was further divided into 31 provincial scales. Shandong and Jiangsu Provinces, which are the first and seventh largest emission sources in China, respectively, were identified as significant sources at Cape Hedo. These sources showed day-to-day variation in their contributions, and the highest contribution from Shandong Province occurred on April 23, whereas that from Jiangsu Province occurred on April 22.
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| 2.
論文（リポジトリ） |
論文（リポジトリ）
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Itahashi, Syuichi ; Hatakeyama, Shiro ; Shimada, Kojiro ; Tatsuta, Shiori ; Taniguchi, Yuta ; Chan, K. Chak ; Kim, Pyo Yong ; Lin, Neng-Huei ; Takami, Akinori
概要:
An intensive observation campaign at Cape Hedo, Okinawa, Japan was conducted from late October to early November 2015 to investigate the behavior of long-range transported atmospheric pollutants. During this period, sulfate
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(SO_4^<2->) was the dominant aerosol component. The sources of SO_4^<2-> were estimated by using the air quality model with the tagged tracer method. The main source of high SO_4^<2-> concentration varied day-to-day. When the westerly wind was dominant (October 27), the main source was anthropogenic SO_2 emissions in China. When the northerly wind prevailed (November 1), the impact of volcanoes in western Japan was significant and the conversion ratio from SO_2 to SO_4^<2-> was lowest, at less than 70%, because of the faster transport. During the latter part of the campaign, the northerly to easterly winds were prominent, and the impacts of Korea, Japan, and ships on SO_4^<2-> observed at Cape Hedo were also clear. When the contributions from Korea, Japan, and ships were the highest (November 4), the conversion ratio was also the highest, at greater than 95% because of long-range transport. The modeled sources of volcanoes and ship emissions corresponded well with the observed coarse-mode SO_4^<2-> and V/Mn ratio, respectively. The mutual evaluation of sources from model and observations enable SO_4^<2-> sources to be estimated with higher confidence.
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