The SAGE II (Stratospheric Aerosol and Gas Experiment II) sensor was launched into a 57 degree inclination orbit aboard the Earth Radiation Budget Satellite (ERBS) in October 1984. During each sunrise and sunset encountered by the orbiting spacecraft, the instrument used the solar occultation technique to measure attenuated solar radiation through the Earth's limb in seven channels centered at wavelengths ranging from 0.385 to 1.02 micrometers and to measure stratospheric aerosols, ozone, nitrogen dioxide, and water vapor.

The data SAGE II collected were integral to confirming human-driven changes to ozone, and thus contributed to the 1987 Montreal Protocol that banned certain harmful chemicals. SAGE II observations helped to confirm that ozone ceased decreasing in response to this action.

Major results from SAGE II include illustrations of the stratospheric impact of the 1991 Mount Pinatubo eruption, identification of a negative global trend in lower stratospheric ozone during the 1980s, and quantitative verification of the positive water vapor feedback in current climate models.