Abstract
According to the lidar measurements of stratospheric aerosol for 2 years after the large eruption of El Chichon (Mexico, March and April 1982), the vertically integrated backscattering coefficient showed large fluctuations for about 5 months after the eruption and began to decrease at the end of November 1982. The e-folding decay time of the integrated backscattering coefficient was about 5.6 months for the period from November 1982 to May 1983 and it was about 12.4 months for the period after May 1983. The peak height of the backscattering coefficient and the centroid height of the integrated backscattering coefficient became lower in the earlier decay period, suggesting sedimentation of particles. The time variation of the peak height of the aerosol layer implies a decrease in the mean radius of particles around the peak of the aerosol layer. It is speculated that sedimentation of aerosols played a significant role in the removal of aerosols from the stratosphere in the period from about 6 months to one year after the eruption.
