Aircraft Emissions: Potential Effects on Ozone and Climate - A Review and Progress Report
INSTITUTE FOR DEFENSE ANALYSES ALEXANDRIA VA
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A critical review is made of information relative to effects of aircraft emissions NOx, SO2, H2O projected to 1990 on the earths protective ozone shield and on mean surface temperature, as estimated from appropriate mathematical models. Potential biological effects are not reviewed. The review provides information showing the large uncertainties in computations of effects on ozone, due to uncertainties in NOx emission indices accepted values may be several-fold low, in chemistry, in troposphere-stratosphere interchange processes, and in future stratospheric composition principally chlorine content estimates of effects can be expected to change as new data are obtained. Current results indicate that aircraft NOx effects on the ozone column change sign with aircraft altitude subsonic aircraft, cruising at 6-km to 14- km altitude, enhance or have almost no effect on the ozone column supersonic aircraft mach-2 class, cruising at 16-km to 19-km, reduce total ozone, but, for given NOx rates, by amounts less than previously reported. Computations based on a high rapid growth estimate for the 1990 total fleet of subsonic and supersonic aircraft, assuming current engines and accepted NOx emission indices, including an estimated 142 Concordes and Tupolevs, showed an average ozone enhancement in the Northern Hemisphere of about 0.4 percent to 0.9 percent, varying with season.
- Atmospheric Physics