IMPLICATIONS OF NOY EMISSIONS FROM SUBSONIC AIRCRAFT AT CRUISE ALTITUDE

The exhaust emissions from civil subsonic aircraft at cruise altitude are important man-made sources that pollute the upper troposphere and the lower stratosphere (8-12 km). The formation of NOy species from NO x, both before and after the exit nozzle, have created increasing envi ronmental concerns. Flight histories of Boeing 747-400 aircraft during the cruise stage between selected city pairs have been simulated usin g a computer program developed at Cranfield University. The passive di stribution of NOx and HNO3 is calculated using the UGAMP three-dimensi onal chemical transport model. The sink of NOx, which is HNO3, is para meterized using an exponential decay process with an altitude-dependen t lifetime. The model also includes transport by advection, vertical d iffusion and convection. These simulations for January and Jury are an alysed in terms of the resulting mean volume mixing ratios for both NO x and HNO3.