Exploring the Global Importance of Atmospheric Ammonia Oxidation

Ammonia (NH3) is the dominant source of reduced nitrogen in atmosphere, emitted primarily from agricultural activities. Current representations NH3 global chemical transport models (CTMs) largely focus on thermodynamics governing aerosol formation, ignoring atmospheric oxidation with hydroxyl (OH) radical since this process slow and therefore assumed to not be significant. In study, we incorporate an explicit mechanism simulate chemistry using GEOS-Chem CTM. While inclusion pathway does result a meaningful impact ammonia burden, average annual reduction approximately 3%, leads small but significant changes key species, particularly over Indian subcontinent where surface concentrations ozone (O3), OH, nitrate see reductions 5%. Our results also suggest that accounts for around 8% (and up 16%) anthropogenic nitrous oxide (N2O) source, important implications climate designed accurately changing emissions. We conduct suite simulations emission estimates representative concentration (RCP) trajectories 2100, which will become increasingly N2O NOx under future scenarios, accounting 21% Given large uncertainties process, use sensitivity analysis demonstrate wide range response; our support need further research better constrain reaction pathways associated yields.