AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Modelling of Amines in the Global Atmosphere: Impacts of Oxidation and Aerosol Uptake
FANGQUN YU, Gan Luo, University at Albany
Abstract Number: 403 Working Group: Aerosol Chemistry
Abstract Amines have received increasing attention in recent years as theoretical, laboratory, and field measurements indicate that amines may considerably enhance particle formation and growth. Recent measurements taken in the CLOUD (Cosmics Leaving Outdoor Droplets) chamber experiments at CERN indicate that dimethylamine concentration ([DMA]) of several pptv can substantially enhance nucleation rates but such an enhancement drops significantly as [DMA] decreases below a few pptv. In order to determine the contribution of ternary nucleation involving amines to the atmospheric particle production, it is critical to know the concentrations of key amines and their spatiotemporal variations in the atmosphere. In the present work, we attempt to simulate the global distributions of amines in the air with a global chemistry transport model (GEOS-Chem). The key processing controlling amines concentrations (including emission, deposition, transport, oxidation, and aerosol uptake) are considered and the simulated results are compared to the limited measurements. Our simulations indicate that amines have a very short lifetime (as short as 1-2 hours over some regions) due to oxidation and aerosol uptake. As a result, relatively high concentrations of amines are generally confined to the source regions. With the estimated global DMA emission flux from the literature, our simulations indicate that the annual mean [DMA] is generally less than 1 pptv in the boundary layer over major continents and below 0.1 pptv over oceans and above boundary layer. Total concentrations of methylamines amines (including monomethylamine, dimethylamine, and trimethylamine) are about one order of magnitude higher. The uncertainty in the model simulations, sensitivity of simulated amines concentrations to aerosol uptake coefficients, and implications of results to atmospheric new particle formation will be discussed.