Atmospheric ammonia and particulate inorganic nitrogen over the United States

摘要: Abstract. We use in situ observations from the Interagency Monitoring of PROtected Visual Environments (IMPROVE) network, Midwest Ammonia Project, 11 surface site campaigns as well Infrared Atmospheric Sounding Interferometer (IASI) satellite measurements with GEOS-Chem model to investigate inorganic aerosol loading and atmospheric ammonia concentrations over United States. IASI suggest that current emissions are underestimated California springtime Midwest. In this underestimate likely drives nitrate formation model. However remaining continental States we find simulation is biased high (normalized mean bias > = 1.0) year-round, except Spring (due season). None uncertainties precursor emissions, uptake efficiency N2O5 on aerosols, OH concentrations, reaction rate for nitric acid, or dry deposition velocity acid able explain bias. reducing 75% their simulated values corrects (as ammonium) US. mechanism potential reduction unclear may be a combination errors chemistry, sub-grid near-surface gradients. This "updated" reproduces PM captures strong seasonal spatial gradients gas-particle partitioning across estimate nitrogen makes up 15−35% fine mass US, fraction increase coming decade, both decreases sulfur increases emissions.