THE EFFECTS OF THE CONVERSION OF NITROGEN-OXIDES IN AIRCRAFT EXHAUST PLUMES IN GLOBAL-MODELS

A parametrization is needed in global models to account for the sub-gr id chemical processes taking place in the plume of an aircraft, since these processes can cause the conversion of a considerable amount of t he emitted NOx to reservoir species, such as HNO3. For this purpose, t he chemical conversions of nitrogen oxides in the plume of an aircraft were investigated with a newly developed model. The calculated fracti ons of different nitrogen compounds formed within 24 hours in the exha ust plumes, differentiated for the global domain and season, were used to modify the original aircraft NOx emissions from the ANCAT emission inventory tb emissions of various nitrogen compounds and we applied t hese to the global Chemistry Transport Model KNMI (CTMK). The results obtained imply that neglect of aircraft plume processes in global mode ling leads to an overestimation of the NOx and O-3 perturbations. Comp ared with a CTMK calculation with unmodified aircraft NOx emissions, t he NOx perturbations in the North Atlantic flight corridor (NAFC) decr eased by 15%-55%, due to conversions in the plumes. The resulting O-3 perturbation decreased by 15%-25%.