Unexpected Behavior of Secondary Organic Aerosols May Lead to Improved Climate Models


Secondary organic aerosols (SOA) have significant impacts on direct and indirect forcing of climate. SOAs formed from gas-phase precursors represent one of the most abundant aerosol components in the atmosphere, but current models under predict the amounts of SOA actually observed. Considerable research has been directed toward understanding and modeling the “missing SOA source.” Key insights into this dilemma may result from a DOE-funded laboratory study on the evaporation rates of laboratory-generated and ambient particles in the Atmospheric Radiation Measurement (ARM) CARES field campaign. The investigators used Single Particle Laser Ablation Time-of-flight mass spectrometer (SPLAT-II) to show that adsorbed organic coatings on SOA can reduce the rates of evaporation by 10 to 100 times, making the particles more persistent than predicted using assumptions in current models. This work highlights the need for improvements of SOA representation in global models which account for the “missing SOA.”


Vaden, T.D., D. Imre, J. Beránek, M. Shrivastava, and A. Zelenyuk. 2011. “On the Evaporation Kinetics and Phase of Laboratory and Ambient Secondary Organic Aerosol,” Proceedings of the National Academy of Sciences U.S.A., available online January 24, 2011, doi: 10.1073/pnas.