A series of three Sun photometer instruments launched by NASA to investigate aerosol, ozone, and nitrogen dioxide levels in the Earth's atmosphere. SAGE I was launched in February 1979 and collected solar radiance data during a period of nearly three years. This was combined with meteorological data from the National Oceanic and Atmospheric Administration to yield altitude profiles of aerosol extinction and ozone and nitrogen dioxide concentrations. SAGE II was launched in October 1984 to investigate the same targets and water vapour. It revealed that the eruption of Mt Pinatubo in the Philippines caused a loss of nitrogen dioxide in the stratosphere, and it increased knowledge of the Antarctic ozone hole. Sage III, with expanded wavelength coverage, was scheduled for launch in December 2001 aboard a Russian spacecraft and in 2004 to the International Space Station.
Subjects: Astronomy and Astrophysics.