Das Projekt "Formation processes and radiative properties of particles in aircraft wakes" wird vom Umweltbundesamt gefördert und von Fraunhofer-Gesellschaft zur Förderung der Angewandten Forschung, Fraunhofer-Institut für Atmosphärische Umweltforschung durchgeführt. Objective: The project aims at a better understanding of the effect of aircraft exhaust on aerosol and cloud formation and of their impact on the climate. It will examine the interaction between aircraft emission (gases and particles), cloud and particles formation and radiative energy transfer in the upper troposphere. For this, the formation of new particles (contrails and aerosols) in the wake of subsonic airplanes will be investigated in order to determine the microphysical and radiative properties of contrails as function of the meteorological conditions during their life cycle, i.e. from the early phase of jet expansion to a cirrus like stage. This project includes the combination of ground based observations by lidar, aircraft 'in situ' observations (Falcon) and numerical modelling. General Information: The structure and evolution of contrails in the wake of subsonic aircraft as well as their interactions with aerosols will be studied by combining in situ measurements, ground observations (LIDAR) and modelling of the wake and of the contrails. For the purpose of in situ measurements, the meteorological research aircraft 'Falcon' of DLR will be operated. To allow an undisturbed inspection of the produced contrail through its life cycle, single commercial aircraft producing a contrail will be guided through the temporary restricted area TRA 307. The deliverables of the project will include: a) Computer codes for modelling of the wakes, modelling of particles formation in the wakes and modelling of the life cycle of contrails in relation with meteorological, properties of the upper atmosphere. b) Data set concerning the ground observation of contrails (by Lidar including altitude of contrails, horizontal and vertical extent, cross-section area, backscatter, optical depth, degree of depolarisation etc.) and the in situ measurements. The in situ measurements will include the basic atmospheric state parameters (temperature, pressure, humidity, solar irradiance) inside and outside the wake, aerosol and cloud particle size distributions, airborne measurements of Cloud Condensation Nuclei (CCN), Cloud/residual properties in the range 0.1-3.5 m, airborne measurements of particles phase function, ambient water vapour content and cloud water content, elemental composition, light absorption measurements, morphology of the particles collected with the counter flow virtual impactor (post flight analyses). c) Final report assessing the influence of aircraft emissions on the physical and atmospheric processes in the upper troposphere, with special emphasis on particles formation, particle and cloud interactions and radiative energy transfer. This final report will also develop parameterisation schemes, describing the formation, evolution and radiative properties to be used in large scale circulation models. Prime Contractor: Centre National de la Recherche Scientifique (CNRS), Centre de Geochimie de la Surface (UPR 6251), Strasbourg; France.