Abstract
High concentrations o ozone, principally stratospheric origin, are observed in spring at the northern Kyushu district. In order to estimate the long-term ozone variation and the effects of the weather condition, the observations of ozone were made for about 6 years at an unpolluted mountain-peak, and the concentrations of beryllium-7 were measured for 50 days in spring and fall.
The monthly maximum ozone at the mountain-peak was mainly observed in April and May, having the values of 44-60 ppb as the averages of all l-hr ozone during the months. The seasonal variation was almost similar to that in the northern hemisphere, where ozone maxima in spring and ozone minima in fall have been observed. Ozone concentrations at the mountain-peak were slightly reduced year by year, and the rate of this reduction was estimated as 4.7%/ Year.
Average concentrations of beryllium-7 were (5.7±2.0)×10o3 Bq/ m3 in spring and (5.1±2.0)×10-3 Bq/ m3 in fall, Concentrations of beryllium-7 were increased under these meteorological conditions such as the behind of a cold front and the behind of high-pressure. The ozone concentrations at the mountain-peak are relatively high under these meteorological conditions such as a troughof atmospheric pressure and atmospheric high-pressure system. The ozone concentrations affected by a northerly air mass at mountain-peak are higher than those by a southerly air mass.
