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 emp loyed to estimate the impact of present and future sub- and supersonic aircraft NO, emissions on ozone. Multi-annual simulations are perform ed to investigate changes of large-scale climatological features. An i ncrease of tropospheric ozone of 3-4% is found in the Northern Hemisph ere for a present day scenario, independently from season. No indicati ons for significant ozone changes are indicated in the lower stratosph ere. NO, emissions expected for the year 2015 by sub- and supersonic ( 500 civil aircraft, Mach 2.4, EINOx = 15) air traffic yield much large r ozone changes in the model. An ozone increase of approximately 15% i s predicted near the cruise altitude of future subsonic air traffic. T his is accompanied by a clear ozone reduction of 3-4% in the lower str atosphere caused by supersonic aircraft. A stronger decrease of ozone is detected in polar winter due to the impact of heterogeneous reactio ns on polar stratospheric clouds. (C) 1998 Elsevier Science Ltd. All r ights reserved.