Impact of present and future aircraft NOx and aerosol emissions on atmospheric composition and associated direct radiative forcing of climate
Résumé
Aviation NOx emissions have not only an impact on global climate by changing ozone and methane levels but also contribute to deteriorate local air quality. In order to properly assess the co-benefit with air quality improvement and the trade-off with the climate change associated with CO2, it appears essential to better quantify the climate impact of aircraft NOx emissions. A new version of the LMDZ-INCA global model, including both tropospheric and stratospheric chemistry and the sulfate-nitrate-ammonium cycle, is applied to re-evaluate the impact of aircraft 20 NOx and aerosol emissions on climate. The results confirm that the efficiency of NOx to produce ozone is very much dependent on the injection height. For the baseline simulation and reference scenario this efficiency is 6.6 TgO3/TgN. The efficiency increases with the background methane and NOx concentrations and with decreasing aircraft NOx emissions. The same findings translate to the associated ozone radiative forcing which exhibits a fairly constant value per ozone mass change of 3.4 mW/m 2 /TgO3. The methane lifetime variation is less sensitive 25 55 reduces the overall mitigation potential.
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