Impact of future subsonic aircraft NO sub(x) emissions on the atmospheric composition

The effect of future subsonic aircraft emissions on the chemical composition of the atmosphere is investigated by means of the coupled dynamic-chemical circulation model ECHAM3/CHEM. Present (1992) and future (2015 and 2050) atmospheric compositions are simulated with three sets of time slice experiments. Expected changes of the sea surface temperatures (SST), surface emissions of CFCs, greenhouse gases (GHG), and NO sub(x) (=NO+NO sub(2)) are prescribed. Model results show future increases in NO sub(x) and O sub(3) due to aircraft NO sub(x) emissions, which scale almost linearily with the magnitude of the emission. The calculated climate change reduces the NO sub(x) concentration as well as its increase due to aircraft emissions by more than 10% at flight altitude in 2015. However, the aircraft induced ozone perturbation decreases only slightly when climate change is regarded.