POTENTIAL IMPACT OF SO2 EMISSIONS FROM STRATOSPHERIC AIRCRAFT ON OZONE

Renewed interest in the potential impact of stratospheric aircraft on atmospheric ozone has focused on emissions of nitrogen oxides (NOx). T his work shows that enhancement of the sulfate aerosol layer by aircra ft emissions of sulfur could be more significant to the ozone impact t han emission of NOx, especially when emissions of NOx in future engine s are reduced by a factor of three from present engine designs. Our ca lculations show that increases in the aerosol surface area of the stra tosphere by factors of two to three are expected if significant amount s of aircraft-emitted sulfur are converted to sulfuric acid and underg o homogeneous nucleation in the aircraft plume. This possibility is su pported by both in situ stratospheric observations and plume/wake mode ling.