Laboratory Studies of Sulfuric Acid-Water-Ammonia Ternary Homogeneous Nucleation Under Conditions Relevant to the Lower Troposphere

The goal of the project is to investigate nucleation rates and aerosol growth rates of the sulfuric acid-water-ammonia system as a function of sulfuric acid and ammonia concentrations, relative humidity, and temperature under lower tropospheric conditions. Project Description and Methods: Laboratory kinetics studies will be conducted with a fast flow reactor coupled with two chemical ionization mass spectrometers (CIMS) to simultaneously detect low concentrations of sulfuric acid and ammonia. This will be the first time that ammonia ternary nucleation studies are made by measuring both sulfuric acid and ammonia precursor concentrations to test aerosol nucleation theories. These experimental observations are essential to reduce uncertainties associated with the loading, distributions and fate of atmospheric aerosols and thus ultimately reduce the uncertainties in climate change predictions related to aerosol and cloud radiative forcing.