Abstract
High oxidant concentrations are generally measured in the springtime in rural regions in Japan as well as in Niigata area. The possible origin is the downward transport of stratospheric ozone or the phtochemical production near the ground. If the intrusion of stratospheric ozone is the main origin, increased concentrations of beryllium-7 that is the radioactive isotope formed in stratosphere by cosmic rays will also be observed at the same time. From this point of view, beryllium-7 concentrations in the springtime were measured for 3 years from 1983 through 1985, compairing with the ozone concentrations measured at a rural point in Niigata area.
The concentration peaks of beryllium-7 were found on the backside of high pressure systems in well agreement with the ozone's. Significant correlations wcre obtained between beryllium-7 and ozone concentration for each year. This indicates downward transport of stratspheric air markedly influence to ground-level ozone concentration. But, the concentration variation of ozone and beryllium-7 were not always the same in details because of their differences of physical form and origin.
