Acetone and PAN in the upper troposphere: impact on ozone production from aircraft emissions

The role of acetone and PAN in the chemistry of the upper troposphere has been investigated with a time-dependent photochemical box model. The results show that acetone strongly enhances aircraft-related ozone production, as exemplified in this study over North Atlantic during summer. For typical flight corridor conditions, the inclusion of about 1 nmolmol−1 acetone more than doubles net ozone production by aircraft NO emissions and resolves discrepancies between observations and several global model predictions. The actual magnitude of the acetone-attributed enhancement of ozone production can, however, be reduced by PAN formation which acts as a sink for NOx (NO+NO2) and also lowers the OH/HO2 ratio.