European scientific assessment of the atmospheric effects of aircraft emissions

This report is a scientific assessment aimed at reviewing the present state of knowledge concerning the various aspects related to the impact of both subsonic and supersonic aircraft on the upper troposphere and lower stratosphere. It was initiated by the European Commission, DG XII/D, Environment Directorate, and commissioned to an expert group chaired by Dr G. P. Brasseur. Although it has inevitably a European flavour, it is not based only on the European funded research but on the broad international scientific knowledge. The goal is to make a critical evaluation of the scientific results in order to provide the best available information for taking appropriate political decisions regarding the future technological development of aircraft and their operations, in spite of the still persistent uncertainties. The report should be considered as part of the European research efforts concerning the potential atmospheric impacts of aircraft emissions, which are conducted by the Environment and Climate Research Programme of the European Commission (EC) as well as by national programmes of the Member States of the European Union. The objective of this research is to improve our understanding and our ability to predict any chemically induced changes in the ozone layer and the climate caused by aircraft emissions. Research activities on engine technologies for reducing aircraft emissions, complementary to the atmospheric aircraft impacts, are supported by the Industrial and Materials Technologies (IMT) Research Programme (Area 3: Aeronautics). Both Programmes are part of the multi-annual Framework Programmes of the EC-DG XII for RDT activities in Europe. As a response to the concern on the increasing air traffic the fate of its emissions taking into consideration the U.S. programme on supersonic transport effects, the European efforts have been concentrated since 1992 on the effects of subsonic transport. For the first time, an integrated study aiming toward a better understanding of the atmospheric effects of emission of subsonic aircraft, the AERONOX project, was supported under the Environment Research Programme. After the initiation of AERONOX, further research activities have been supported by the EC such as the POLINAT, STREAM, MOZAIC, AEROCHEM. AEROCONTRAIL and AEROTRACE projects. At a national level, a considerable number of individual programmes on aircraft impacts were also inititated, such as the ``Comite Avion Ozone" in France, the "Pollutions from Ai