Laboratory studies of multi-component aerosol nucleation involving organic amine compounds under conditions relevant to the lower troposphere will be carried out to investigate (1) the effects of amines on sulfuric acid aerosol nucleation, (2) how ammonia and amines together enhance sulfuric acid nucleation compared to ammonia or amines alone, (3) the effects of amines on sulfuric acid aerosol nucleation in the presence of organic acids (e.g., acetic or oxalic acids), (4) whether organic acids and ammonia/amines can produce new particles without sulfuric acid, and (5) how amines play different roles in the initial formation of molecular clusters and their subsequent growth to aerosol particles. The composition of these laboratory-generated aerosols will be compared with that of ambient aerosols in various atmospheric environments to understand the roles that organic compounds play in the aerosol nucleation processes.
Climate change is one of the most important scientific and socioeconomic issues of the day. Aerosol-cloud-climate interactions are not well enough understood to make reliable predictions about future climate. Nucleation is a predominant source of new particles and thus is an important process that controls aerosol concentrations, cloud condensation nucleus (CCN) populations and, ultimately, cloud abundance. New particles may also have significant indirect effects on climate through their modification of cloud properties such as albedo, lifetime, and precipitation efficiency. Indeed, aerosols represent the greatest source of uncertainty in climate modeling, and thus understanding the nucleation and growth processes that govern aerosol formation are a high priority in atmospheric research. The results of this project will help to reduce the uncertainties in the current aerosol nucleation theories and the uncertainties in the predictions of CCN concentrations in regional and global aerosol models. Through involvement in this project a postdoctoral fellow, a PhD student, and several undergraduate students will gain valuable knowledge and experience in atmospheric chemistry, aerosol technology, and climate science.
