CONTRAILS

Exhaust emissions from jet aeroplanes contain large amounts of water vapour which, under certain atmospheric states, will condense to form elongated cloud-like condensation trails in the sky. These contrails can have an environmental impact by modifying the radiative balance of the Earth-atmosphere system. This perturbation is caused by radiative forcing due to the contrails themselves, and possibly also due to the formation of persistent cirrus clouds which might not otherwise have existed.

The focus of the Contrails project was to develop and demonstrate an EO-based service in support to the continuous assessment of the environmental effects of increasing volumes of air traffic, by monitoring the daily contrail and cirrus cloud coverage, for one year, over Europe and the North Atlantic.

Contrails were mapped intensively for one year (2004) using several satellite sensors in order to capture as best as possible the diurnal variation. Cirrus cloud coverage and properties were also mapped using satellite data. By comparing the cirrus cloud maps with air traffic density maps, the relationship between changes in cirrus and air traffic density were investigated. An assessment of the radiative forcing of both the contrails and the cirrus changes were made. Finally, an independent assessment of EUROCONTROL's contrail formation model was made by comparing model based contrail maps with the satellite derived contrail maps.

With the aim of providing historical context for the one year intensive study period, contrail maps for the years 1985, 1990, 1995, 2000 were also prepared.