Small-scale variations in ozone concentration in low mountains

In a relatively low mountain area adjacent to Matsuyama city in Japan, ozone concentration variations were studied at spatial scales of O(10)∼O(103) m. Walking mobile measurements were complemented by vertical profiling, wind measurements, and passive sampling. The broad-scale distribution at O(102)∼O(103) m was found to depend on time of day, atmospheric stability, and geography in ways consistent with previous studies. Well-defined areas of low ozone concentrations O(10) m in width were found at several locations. No distinctive features of these locations were immediately discernible, but detailed examination of the temporal variations coupled with the wind field suggested that the distribution of the low-ozone areas was determined by subtle differences in the terrain topography.