Aircraft emissions and air quality of the tropopause region - a model study of the North Atlantic flight corridor

Aircraft emissions can affect the tropopause region through their impact on chemical and radiative processes. They may thus play a peculiar role for anthropogenically induced modifications of the Earth's climate. The effect of subsonic aircraft emission on the chemical system of the tropopause region is investigated using a special version of the European Air Pollution Dispersion Model (EURAD). Simulations have been carried out for the North Atlantic flight corridor. The role of the composition of the background atmosphere is analysed in particular. The results show a clear dependence of ozone changes as induced by aircraft exhaust on background aerosols. Furthermore, it is argued that mesoscale dynamics, i.e. tropopause foldings, cut-offs lows and streamers causing variations of the background composition at cruise altitudes, may modify the efficiency of ozone formation through aircraft emissions. (Author)