THE ANCAT EC GLOBAL INVENTORY OF NOX EMISSIONS FROM AIRCRAFT/

A three dimensional global emissions inventory for NOx from civil and military aviation has been formulated by a joint European Civil Aviati on Conference/European Commission working group in support of the AERO NOX project ''The Impact of NOx Emissions from Aircraft Upon the Atmos phere at Flight Altitudes 8-15 km''. The inventory was compiled on a r esolution of 2.8 by 2.8 degrees by 1 km in altitude for a 12 month per iod spanning mid-1991 to mid-1992. Traffic movement data were compiled from Air Traffic Control recorded movements and timetables for Januar y, April, July and October and combined with an airframe emissions per formance model. The global emission of aircraft NOx was estimated to b e 2.78 Tg NO(2)yr(-1) and the overall emission index for NOx in g NO(x )kg(-1) fuel burnt was 16.8. The estimated NOx emissions are higher th an the most comparable inventory (NASA, 1990) by a factor of almost 2. The vertical distribution shows that 60% of the global NOx is emitted at cruise altitudes of 10-12 km. There is a pronounced latitudinal bi as with 93% of the global emissions being in the Northern Hemisphere a nd 70% between 30 and 60 degrees N. The spatial distributions of NOx e missions show some seasonality. Emissions of CO2, H2O and SO2 have als o been estimated at 528, 216 and 0.165 Tg yr(-1), respectively. Althou gh not quantified, the uncertainties in the emissions estimate of NOx from aircraft are discussed and a small overestimation in the traffic movement data base was identified. However, the uncertainties are prob ably smaller than those for natural sources of NOx which are injected into the top of the troposphere. More work is required to refine emiss ion inventories from aircraft. (C) 1997 Published by Elsevier Science Ltd.