SAGE II long-term measurements of stratospheric and upper tropospheric aerosols

Abstract

The Stratospheric Aerosol and Gas Experiment (SAGE) II solar occultation instrument has been making measurements on stratospheric aerosols and gases continually since October 1984. Observations from the SAGE II instrument provide a valuable long-term data set for study of the aerosol in the stratosphere and aerosol and cloud in the upper troposphere. The period of observation covers the decay phase of material injected by the El Chichon volcanic eruption in 1982, the years 1988 - 1990 when stratospheric aerosol levels approached background levels, and the period after the eruption of Mount Pinatubo in 1991. The Mount Pinatubo eruption caused the largest perturbation in stratospheric aerosol loading in this century, with effects on stratospheric dynamics and chemistry. The SAGE II data sequence shows the global dispersion of aerosols following the Mount Pinatubo eruption, as well as the changes occurring in stratospheric aerosol mass and surface area. The downward transfer of stratospheric aerosols into the upper troposphere following the earlier eruption of El Chichon is clearly visible. Estimates have been made of the amount of volcanic material lying in the upper troposphere and the way in which this varies with latitude and season.