1Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
2Johannes-Gutenberg-Universität, Institut für Physik der Atmosphäre, Mainz, Germany
3Université Blaise Pascal, LaMP, Clermont-Ferrand, France
*now at: Forschungszentrum Jülich, Institut für Energie- und Klimaforschung, Jülich, Germany
**now at: Institute for advanced sustainability studies, Potsdam, Germany
Abstract. The investigation of the impact of aircraft parameters on contrail properties helps to better understand the climate impact from aviation. Yet, in observations, it is a challenge to separate aircraft and meteorological influences on contrail formation. During the CONCERT campaign in November 2008, contrails from 3 Airbus passenger aircraft of type A319-111, A340-311 and A380-841 were probed at cruise under similar meteorological conditions with in-situ instruments on board the DLR research aircraft Falcon. Within the 2 min old contrails detected near ice saturation, we find similar effective diameters Deff (5.2–5.9 μm), but differences in particle number densities nice (162–235 cm−3) and in vertical contrail extensions (120–290 m), resulting in large differences in contrail optical depths τ (0.25–0.94). Hence larger aircraft produce optically thicker contrails.
Based on the observations, we apply the EULAG-LCM model with explicit ice microphysics and in addition the Contrail and Cirrus Prediction model CoCiP to calculate the aircraft type impact on young contrails under identical meteorological conditions. The observed increase in τ for heavier aircraft is confirmed by the models, yet for generally smaller τ. An aircraft dependence of climate relevant contrail properties persists during contrail lifetime, adding importance to aircraft dependent model initialization. We finally derive an analytical relationship between contrail, aircraft and meteorological parameters. Near ice saturation, contrail width × τ scales linearly with fuel flow rate as confirmed by observations. For higher saturation ratios approximations from theory suggest a non-linear increase in the form (RHI–1)2/3. Summarized our combined results could help to more accurately assess the climate impact from aviation using an aircraft dependent contrail parameterization.