Impact of aircraft NOx emissions on tropospheric and stratospheric ozone.: Part II:: 3-D model results

The global three-dimensional dynamic-chemical model ECHAM3/CHEM is employed to estimate the impact of present and future sub- and supersonic aircraft NO, emissions on ozone. Multi-annual simulations are performed to investigate changes of large-scale climatological features. An increase of tropospheric ozone of 3-4% is found in the Northern Hemisphere for a present day scenario, independently from season. No indications for significant ozone changes are indicated in the lower stratosphere. NO, emissions expected for the year 2015 by sub- and supersonic (500 civil aircraft, Mach 2.4, EINOx = 15) air traffic yield much larger ozone changes in the model. An ozone increase of approximately 15% is predicted near the cruise altitude of future subsonic air traffic. This is accompanied by a clear ozone reduction of 3-4% in the lower stratosphere caused by supersonic aircraft. A stronger decrease of ozone is detected in polar winter due to the impact of heterogeneous reactions on polar stratospheric clouds. (C) 1998 Elsevier Science Ltd. All rights reserved.