The four wave-length extinction coefficients for stratospheric aerosols observed with SAGEII (Stratospheric Aerosol and Gas Experiment II) were analyzed. SAGEII is an occultation sensor which have measured aerosol extinction at 1.02, 0.525, 0.453, 0.385, um from 10 km up to 45 km in altitude since 1985. The eleven years data record from 1985 through 1995 shows the strong increase in the extinction in 1991 after the eruption Pinatubo (June 1991, Philippine). The wavelength dependence of the extinction coefficients also significantly changed after the eruption, showing the existence of large particles. Even in the background period before the eruption, the wavelength dependence show significant spatial variation. The wavelength dependence would be good information to investigate micro-physical evolution processes of aerosol particles along with the transportation in the lower stratosphere.
