Potential Ozone Column Increase Resulting from Subsonic and Supersonic Aircraft NOX Emissions

A two-dimensional time-dependent photochemical model developed to describe the meridional distribution of the important trace species in the stratosphere and troposphere continuously throughout the year has been used to estimate the effect on ozone of NOX emissions; supplied by the Federal Aviation Administration (FAA), from a combined fleet of supersonic and subsonic aircraft projected to be operational in 1990. The net effect of this combined fleet is to increase the atmospheric ozone level slightly (maximum local column change <1.5%) for the given chemical system. High-altitude injections of NOX result in a decrease in the ozone column above approximately 15-16 km, as predicted in numerous previous studies. However, this reduction is smaller than the increase in the ozone column resulting from the production of ozone through the methane-smog chemical cycle resulting from the large amount of NOX deposited at lower altitudes (L 13 km). Relative latitudinal and seasonal variations of the ozone change are large, being greatest in the fall and least in the late spring and summer seasons. Since the changes in the ozone column are sensitive to the methane-smog reaction system, more information regarding the rates at which these reactions proceed is needed to affirm the present initial estimates.