Contribution of Volcanic SO2 Emission to High Concentration PM2.5under Summertime Pacific High Condition

Yuki Yamamura, Shunji Niiya, Hisao Chikara, Shuhei Nakagawa, Zhe Wang, Itsushi Uno
Journal of Japan Society for Atmospheric Environment / Taiki Kankyo Gakkaishi  
High PM 2.5 concentrations (daily mean exceeding 50 µg/m 3 ) were observed from July 16 to 21, 2018, over a wide area of Japan. The surface level aerosol observation data by the Aerosol Chemical Speciation Analyzer (ACSA-14) were used for the analysis of the PM 2.5 compositions, and the Community Multi-scale Air Quality (CMAQ) were used for the detailed analysis of the observation data. Our findings from this study can be summarized as follows: 1) The PM 2.5 was mainly composed of SO 4 2− . SO
more » ... emitted from the Sakurajima volcano is converted to SO 4 2− over the East China Sea, then transported to the Japan Sea region along the marginal flow of the Pacific High. SO 4 2− over the Japan Sea, then penetrates to the San-in and the Hokuriku area by the sea breeze. 2) A sensitivity analysis determined that the volcanic SO 2 contribution was 80% at the sea near Sakurajima, 70% at the Hokuriku and off the coast of the San-in area. 3) The Process analysis of CMAQ showed that SO 4 2− near Sakurajima was formed by a gas phase reaction in the daytime and the liquid phase reaction in the clouds, then transported out by horizontal advection and diffusion. SO 4 2− at the Japan Sea increased by horizontal advection and diffusion. It indicated that SO 4 2− formed near Sakurajima was transported to the Japan Sea.
doi:10.11298/taiki.55.169 fatcat:4anzkvxsqjat5cpb42zm6ben34