The Atmospheric Lifetime Experiment and the Global Atmospheric Gas Experiment (ALE/GAGE)

The ALE/GAGE project was designed to determine the global atmospheric lifetimes of the chlorofluorocarbons CCl3F and CCl2F2 (F-11 and F-12), which had been identified as the main gases that cause stratospheric ozone depletion. The experimental procedures also provided the concentrations of CH3CCl3, CCl4 and N2O. The extended role of the project was to evaluate the mass balances of these gases as well. Methylchloroform (CH3CCl3) serves as a tracer of average atmospheric OH concentrations and hence the oxidizing capacity of the atmosphere. Nitrous oxide (N2O) is a potent greenhouse gas and can also deplete the ozone layer. Measurements of these gases were taken with optimized instruments in the field at a frequency of about 1 sample/hr. Toward the end of the present project methane measurements were added to the program. The final report deals with the research of the Oregon Graduate Institute (OGI) as part of the ALE/GAGE program between 4/1/1988 and 1/31/1991. The report defines the scope of the OGI project, the approach, and the results.