How does a 10-fold pulse increase of aircraft-related NO x impact the global burdens of O3 and secondary organic aerosol (SOA)?

Abstract

Aircraft emissions are an important and growing global source of nitrogen oxides (NO x ). At cruising altitude, the atmosphere is particularly NO x -sensitive and aircraft emissions contribute to ozone (O3) production and oxidation of volatile organic pollutants that ultimately produce secondary organic aerosol (SOA). Rapid growth of the global fleet of aircraft and the number of flights require a careful investigation on the atmospheric impact of potential increases in total aircraft-emitted NO x . In this study, we simulated atmospheric composition before, during and after two 10× pulses of total aircraft NO x emissions, one in winter and one in summer of 2007. Results showed that the initial NO x enhancement (up to 3.25% averaged over the globe) was removed after the first 2 months and the change in O3 burden increases for 5 months (up to 3.1 and 2.7% averaged over the globe, respectively, for winter and summer perturbations). The NO x and O3 enhancements follow previously observed temporal patterns, but SOA showed strong season-specific results. During the summer, the NO x pulse decreased total secondary organic gases (SOGs) and SOA burdens, suggesting an inverse relationship with enhanced oxidation. During the winter, the NO x pulse increased the SOG and SOA burdens with SOA lagging SOG. The SOG enhancement has a spatio-temporal pattern similar to NO x . The highest changes in SOA and SOG burdens of different regions during the summer and winter pulse increases were below 1.6%. However, O3 pollution with burden increases as high as 8% in the winter months and 6% in the summer months of the northern hemisphere may even represent an air quality concern.