Issues related to aircraft take-off plumes in a mesoscale photochemical model

•We exploit the subgrid scale processes of an Eulerian mesoscale model.•We simulate the dispersion of aircraft plumes at take-off with a mesoscale model.•We examine, using numerical experiments the sensitivity of plume's dilution and chemical composition•The mixing properties mainly determine the plume's dispersion.

The physical and chemical characteristics of aircraft plumes at the take-off phase are simulated with the mesoscale CAMx model using the individual plume segment approach, in a highly resolved domain, covering the Athens International Airport. Emission indices during take-off measured at the Athens International Airport are incorporated. Model predictions are compared with in situ point and path-averaged observations (NO, NO2) downwind of the runway at the ground. The influence of modeling process, dispersion properties and background air composition on the chemical evolution of the aircraft plumes is examined. It is proven that the mixing properties mainly determine the plume dispersion. The initial plume properties become significant for the selection of the appropriate vertical resolution. Besides these factors, the background NOx and O3 concentration levels control NOx distribution and their conversion to nitrogen reservoir species.