Impact of present and future aircraft NO_<i>x</i> and aerosol emissions on atmospheric composition and associated direct radiative forcing of climate

Abstract. Aviation NOx emissions not only have an impact on global climate by changing ozone and methane levels but also contribute to the deterioration of local air quality. A new version LMDZ-INCA model, including chemistry both troposphere stratosphere sulfate-nitrate-ammonium cycle, is applied re-evaluate aircraft aerosol climate. The results confirm that efficiency produce very much dependent injection height; it increases with background concentrations decreasing emissions. lifetime variation less sensitive location than change. net radiative forcing (RF) (O3+CH4) largely affected revised CH4 RF formula. positive negative offset each other, resulting in a slightly for present day. However, future, turns negative, essentially due higher concentrations. Additional RFs involving particle formation arise from since increased hydroxyl radical (OH) are responsible enhanced conversion SO2 sulfate particles. Aircraft increase nitrate particles lower troposphere. upper troposphere, favour titration ammonia leading ammonium likely be small or even switch (cooling), depending atmospheric future concentrations, when considered. large uncertainties remain particular indirect forcings associated aerosols, which more uncertain other gaseous species. Hence, additional studies range models needed provide consolidated view. Nevertheless, our suggest reducing primarily beneficial improving