Using measurements from the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) experiment, we show that methyl peroxy nitrate (CHâOâNOâ) is present in concentrations of ~5 - 15 pptv in the springtime arctic upper troposphere. We investigate the regional and global effects of CHâOâNOâ by including its chemistry in the GEOS-Chem 3-D global chemical transport model. We find that at temperatures below 240 K inclusion of CHâOâNOâ chemistry results in decreases of up to ~20 % in NOx, ~20 % in N2O5, ~5 % in HNOâ, ~2 % in ozone, and increases in methyl hydrogen peroxide of up to ~14 %. Larger changes are observed in biomass burning plumes lofted to high altitude. Additionally, by sequestering NOx at low temperatures, CHâOâNOâ decreases the cycling of HOâ to OH, resulting in a larger upper tropospheric HOâ to OH ratio. These results may impact some estimates of lightning NOx; sources as well as help explain differences between models and measurements of upper tropospheric composition.
