The impact of NOx emissions from subsonic aircraft on the atmosphere: a 3D model study of the changes in ozone and radiative forcing for the period 1990-2015
Global air traffic has increased extensively during the last few decades and is expected to increase further over the next 20 years by about 5-6% per year. Emissions of trace gases such as carbon dioxide, nitrogen oxides, hydrocarbons, sulphur oxides, water vapour and soot from aircraft can have environmental effects.
The model results indicate that NOx emissions from aircraft cause an increase in the NOx and ozone concentrations in the upper troposphere and lower stratosphere, and a positive radiative forcing. For 1990 aircraft emissions result in an increase in the NOx concentration at 10-11 km of about 20 ppt in January and 50 ppt in July over the northern mid-latitudes, corresponding to a relative increase of about 50%. The maximum increase in the ozone concentrations due to the aircraft emissions at northern mid-latitudes is about 2.5% in January and 3-4% in July.
The aircraft-induced ozone changes cause a global average radiative forcing of 0.013 W/m2 for January and 0.025 W/m2 for July. The 2015 ANCAT projection, yield 90% higher aircraft NOx emissions than in 1990. As a consequence of this, the calculated NOx perturbation by aircraft emissions increases by about 100% between 1990 and 2015, and the ozone perturbation by about 50-70%. The global average radiative forcing due to the aircraft-induced ozone changes increases by about 50% between 1990 and 2015. The perturbation of ozone due to the aircraft NOx emissions increases faster during this period than that due to NOx surface sources from industry, electricity production and road traffic.
|Author(s)||Valks PJM ; Velders GJM|