Global and regional effects of the photochemistry of CH3O2NO2: evidence from ARCTAS
Using measurements from the NASA Arctic Research of the Composition of\nthe Troposphere from Aircraft and Satellites (ARCTAS) experiment, we\nshow that methyl peroxy nitrate (CH3O2NO2) is present in concentrations\nof similar to 5-15 pptv in the springtime arctic upper troposphere. We\ninvestigate the regional and global effects of CH3O2NO2 by including its\nchemistry in the GEOS-Chem 3-D global chemical transport model. We find\nthat at temperatures below 240 K inclusion of CH3O2NO2 chemistry results\nin decreases of up to similar to 20% in NOx, similar to 20% in N2O5,\nsimilar to 5% in HNO3, similar to 2% in ozone, and increases in methyl\nhydrogen peroxide of up to similar to 14%. Larger changes are observed\nin biomass burning plumes lofted to high altitude. Additionally, by\nsequestering NOx at low temperatures, CH3O2NO2 decreases the cycling of\nHO2 to OH, resulting in a larger upper tropospheric HO2 to OH ratio.\nThese results may impact some estimates of lightning NOx sources as well\nas help explain differences between models and measurements of upper\ntropospheric composition.