Abstract
The final goal of this research is to develop a simple risk evaluation method for SO2 erupted from a Mt. Aso, Kyushu Discricts, Japan. As the first step for that, influences of meteorological conditions on behavior of SO2 were examined by analyzing high SO2 concentration events that hourly concentration is over 50ppb. The high SO2 concentration events occurred under the condition that speed of eastern geostrophic wind is about 30m/s and, solar radiation is relatively small or potential temperature gradient is relatively large, or under the condition that eastern geostrophic wind speed is about 5-20m/s with relatively large solar radiation.
