AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Investigating the Regional Scale Impacts of Amine-Sulfuric Acid New Particle Formation
JAN JULIN, Benjamin Murphy, Tinja Olenius, Oona Kupiainen-Määttä, Lars Ahlm, Saeed Falahat, David Patoulias, Christos Fountoukis, Hanna Vehkamäki, Spyros Pandis, Ilona Riipinen, Stockholm University
Abstract Number: 313 Working Group: Primary and Secondary Aerosols from Agricultural Operations
Abstract New particle formation (NPF) is an important contributor to atmospheric particle number concentration, and therefore an accurate description of the NPF process is essential for large-scale models to be able to correctly predict atmospheric particle number and its sensitivity to available gas phase species. Sulfuric acid is a central compound involved in atmospheric NPF, but to account for observed formation rates other compounds such as ammonia or dimethylamine are needed. Since both ammonia and amines are base compounds, they act to stabilize the sulfuric acid containing clusters and thus to enhance nucleation rates. Agricultural activities, specifically animal husbandry, are an important emission source of both ammonia and methylamines. While atmospheric amine concentrations are much smaller than the ammonia concentration, the role of amines in atmospheric NPF cannot be neglected as they have been shown to enhance formation rates over thousand-fold compared to ammonia.
PMCAMx-UF is a three-dimensional regional chemical transport model, which includes detailed aerosol microphysics and simulates both number and mass/composition size distributions. Thus far PMCAMx-UF has included two NPF pathways: ternary sulfuric acid-ammonia-water and binary sulfuric acid-water. For the present work we have updated PMCAMx-UF to include amines. As a central feature the updated version now also includes the sulfuric acid-dimethylamine NPF pathway in addition to the two aforementioned NPF mechanisms. The model has previously used a semi-empirical description for the ammonia NPF pathway, but in the updated version we treat both the ammonia and dimethylamine NPF pathways with an approach based on first-principles theory. The implemented NPF schemes are based on formation rate data produced by the Atmospheric Cluster Dynamics Code, which utilizes state-of-the-art quantum chemistry results to calculate cluster evaporation rates. We will present results where the updated version of PMCAMx-UF is applied to the European domain to assess the impacts of sulfuric acid-dimethylamine NPF.