Global maps of the Earth’s ozone layer are provided daily by the NASA-furnished Total Ozone Mapping Spectrometer (TOMS) aboard the Japanese Advanced Earth Observing Satellite (ADEOS). The satellite, launched this past August, will allow particular attention to be paid to the Antarctic ozone hole during the coming summer season in the southern hemisphere.
Global ADEOS data are being complemented by those from a similar instrument on the US TOMS-Earth Probe spacecraft, which was orbited in July (see Laser Focus World, August, 1996, p. 11). Earth Probe provides high-resolution images of atmospheric features related to urban pollution, biomass burning (such as forest fires, dust storms, and small volcanic eruptions), in addition to ozone measurements.
The mapping spectrometer gauges ozone concentration by comparing the intensity of ultraviolet light in incident sunlight to that scattered back to the satellite from the Earth`s atmosphere. Instruments already on the Japanese satellite are an Improved Limb Atmospheric Sounder, which measures the vertical profile of ozone and other trace gases in the polar regions; an Interferometric Monitor for Greenhouse Gases, which measures ozone below the orbital track; and a Retro reflector in Space, which permits profiling trace gases as the spacecraft passes over ground-based laser sites.
The TOMS/ADEOS program will monitor global ozone during the years when chloro fluorocarbon-induced depletion is predicted to climax. "Stratospheric concentrations of chlorine are expected to peak near the end of the century and then decline as a result of the Montreal Protocol," notes Arlin Krueger, NASA Goddard (Greenbelt, MD) principal investigator. "[The program] will also measure sulfur dioxide in the atmosphere in the wake of volcanic eruptions and detect volcanic dust hazards to aviation."