Studies of atmospheric N₂O

A large number of measurements of atmospheric N2O have been made by a gas chromatic method. Over a period of 2.5 years, almost daily samples were taken at Mainz. There is a weak annual variation, higher values occurring during the warmer season, and there is no indication of anthropogenic sources. Measurements at mountain stations show a general decrease in mixing ratio with altitude, as do measurements from commercial aircraft along the polar route within the tropopause region. A few stratospheric balloon samples show a pronounced decrease in the stratosphere, in agreement with calculations of Bates and Hayes. These data suggest that the atmospheric lifetime is about 70 years, and that the limiting factor is photochemical destruction. Estimates from seasonal variations and other observations seem to indicate shorter atmospheric lifetimes, however, suggesting additional destruction processes.