Collaborative Research: Characterizing the Cloud Formation Properties of Secondary Organic Aerosol (SOA) Formed from Aqueous Multiphase Chemical Processes

The goal of this project is to examine the climate effects of organosulfate-containing secondary organic aerosol (SOA) by investigating their chemical composition, morphology, and phase state in a laboratory setting, and by parameterizing the resultant data for the prediction of aerosol-cloud interactions. The hypothesis is that certain biogenic volatile organic compound-derived SOA enhanced by aqueous reactions within acidic sulfate aerosol, will serve as more effective ice nuclei particle (INP) and less effective cloud condensation nuclei (CCN), due to the production of highly viscous and less hygroscopic organosulfates.

This research is expected to help improve the understanding of how aerosols impact cloud formation and cloud properties and will contribute to reducing the uncertainties in predicting future climate.

Organosulfate-rich SOA produced from the oxidation of isoprene, β-caryophyllene, and α-pinene, as well as authentic organosulfates (OSs) synthesized at the University of North Carolina, will be systematically examined for their INP and CCN properties during this project. Chemical characterization methods will be used to identify the key species in the OS-rich SOA that alter their INP and CCN properties.

The primary objectives of this research are to: (1) determine how chemical composition, phase state, and morphology affect the CCN and INP activities of OS-rich SOA; (2) measure and quantify how the chemical composition and phase state affect the cloud activation properties of OS-rich SOA during atmospheric aging by heterogeneous hydroxyl radical oxidation; and (3) develop parameterizations in order to generalize the effects of SOA chemical composition, phase and mixing state on the CCN/IN potential of these particles for potential model simulations and field data comparison.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.