Behavior of Secondary Pollutants and Volcanic SO2 over Kyushu during a Spring-Time High Pressure System

• Published in: Journal of Japan Society for Atmospheric Environment / Taiki Kankyo Gakkaishi Vol. 32; no. 6; pp. 404 - 424
• Main Authors: UNO, Itsushi, WAKAMATSU, Shinji, UEDA, Hiromasa, MURANO, Kentaro, SAKAMAKI, Fumio, KURITA, Hedemi, SATSUMABAYASHI, Hikaru, HORAI, Shunichi
• Format: Journal Article
• Language: English
• Published: Japan Society for Atmospheric Environment 1997
• Subjects: long-range transport; nitrate; stratospheric O3; stratospheric SO2; sulfate
• ISSN: 1341-4178; 2185-4335
• DOI: 10.11298/taiki1995.32.6_404

The dispersion of secondary pollutants and volcanic SO2 over the Kyushu area during a spring-time high pressure system was analyzed based on comprehensive observational data. The clockwise air circulation within the high pressure system trapped the air pollutants which resulted in both long-range transport from the Asian continent to Japan and local transport of domestic pollutants. Airplane and surface observations show narrowly peaked SO2 concentration from Mt. Sakurajima volcano during conditions when Kyushu is located at the western boundary of the high pressure system. At the same time, high O3 concentration exceeding 80 ppb were observed over most of Japan (especially the western part). O3 concentration and specific humidity were inversely correlated which indicates strong intrusion of stratospheric O3 into the lower troposphere. The data analysis revealed that the photochemical 03 production due to the anthropogenic NOX emission was about 10-20%. HNO3, nitrate and aldhyde were high concentrations when high local production of O3 was observed. Conversion rates from SO2 to SO42-were determined based on surface observation data trajectory analysis and revealed values of about 2.5%/hour. The present study shows that dispersion pattern of pollutants over Kyushu are very complicated when spring-time high pressure conditions prevailed. The long-range transport from both the mainlad Asia and Japan, as well as volcanic SO2 plume transport and stratospheric 03 intrusion into the lower troposphere combine to be responsible for the observed high concentration of secondary pollutants.