Abstract
Ozone concentration measured at two mountain locations in northern Japan (Teine Mountain in spring 1987 and Hakkoda Mountain in 1983-1987) is used to investigate the 'spring maximum' phenomena of lower tropospheric ozone. Ozone concentration at both mountain locations shows little diurnal variation. At Hakkoda Mountain, ozone concentration is at its maximum in spring. In April and May, the monthly mean concentrations are about 60ppb and 1-hour maximum concentrations are between 90 and 110ppb. In summer, the monthly mean ozone concentration decreases to the level that is observed in winter. In spring, elevated ozone concentrations over 80ppb are accompanied by high temperature under anticyclonic conditions. High positive correlation between ozone concentration and 850mb temperature and negative correlation between ozone concentration and 850 mb relative humidity are found in spring. Whereas, in summer, no relationship is found between ozone concentration and 850mb temperature. We considered that the positive correlation between ozone concentration and temperature in spring results from isentropic downward transport of ozone-rich air in the middle troposphere within a moving anticyclones which successively pass in spring in northern Japan.
