THE EVOLUTION OF AIRCRAFT EMISSIONS IN THE STRATOSPHERE

Distributions of subsonic aircraft emissions are advected as an initia l value problem in a 3D transport model to simulate the evolution of e missions in the stratosphere. The sensitivity of transport to season, analyzed tropopause height and aircraft emissions distribution is anal yzed. The 1/e-folding lifetime of the emissions of the current fleet i s found to be about 50 days, within the range of previous estimates. T he lifetime is shorter in January than in July. Within a 90 day period , approximately 7% of emissions in July and 2% in January are lofted i nto the stratosphere. Pathways for the stratosphere-troposphere exchan ge of emissions are discussed.