Observational study of atmospheric chemistry in the free troposphere in relation to large-scale vertical mixing and diffusion

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Intensive campaign observation for atmospheric chemistry was carried out twice at the Mt. Fuji Weather Station (altitude of 3776m), and Tarou-bou (altitude of 1300m) located at a hillside of Mt. Fuji for about two weeks; during May 26, 2003 to June 13, 2003 and during September 11, 2002 to September 24, 2002. In order to investigate chemical processes coupled with air mass change, the observation was carried out in the season when the advection and the convection are active. Therefore, ^7Be and ^<222>Rn were observed with an assignment of a tracer of the upper air mass and boundary layer air mass, respectively. Other observed species include SO_2, CO, O_3, CO_2, ionic components in rain and fog water, the aerosol number and aerosol chemical components, etc. Moreover, the period between the intensive observations, the continuous data of many chemical species could be acquired. Regarding ^7Be concentration, it was found to be low in summer and high in spring and autumn. This seasonal pat … More tern is attributable to the seasonal variation of the air mass transport from the upper level of the atmosphere. On the other hand, ^<222>Rn had a low concentration level and exhibited a relatively small seasonal change. This seasonal pattern seems to difficult to explain at present. This is the first occasion for both species that annual data were acquired in the free troposphere over Japan. The concentration of SO_2 at the summit of Mt.Fuji showed a seasonal pattern of high in winter and low in summer. It was further revealed that a long-range transport occurs with a passage of a low pressure in winter from the Asian continent. When the transport occurred, SO_2, CO, and ^<222>Rn are transported altogether, thus it was suggested that they were originated from a common source domain. Only once SO_2 plume from Miyake-jima was captured at the summit. This anomalous event may be due to some convective activities off the Honshu southern coast coupled with a southeasterly wind. It seems that the Miyake-jima plume usually does not reach to the altitude of Mt.Fuji. Less