Sullivan Publishes High-Impact Paper in PNAS-Mechanical Engineering - Carnegie Mellon University

Friday, April 26, 2013

Sullivan Publishes High-Impact Paper in PNAS

Assistant Professor Ryan Sullivan has co-authored a high-impact paper appearing in the April 25 edition of the Proceedings of the National Academy of Sciences.  The paper, titled "Bringing the ocean into the laboratory to probe the chemical complexity of sea spray aerosol," is the result of an intensive laboratory experiment as part of the Center for Aerosol Impacts on Climate and the Environment (CAICE) NSF Center for Chemical innovation (CCI), at Scripps Institution of Oceanography/UC San Diego, led by Professor Kimberly Prather.

The research aimed to obtain more accurate measurements of the chemical composition of sea spray aerosol than what had previously been possible due to interference by other particles in the surrounding air at marine sites.  The team created a realistic breaking wave flume to generate aerosol particles with the appropriate chemical and physical properties.

The goal was to determine how changes in the chemistry and biology of the ocean water produced changes in the physicochemical properties of the resulting sea spray aerosol, and the climate-relelvant properties of the aerosol. Along with Dr. Paul DeMott at Colorado State University, Professor Sullivan determined the ice nucleation properties of the sea spray.

This paper describes the results of a 5-day mesocosm experiment, in which the team continuously generated sea spray while periodically adding in different bacteria, algae, phytoplankton, or nutrients. They observed significant changes in the properties of the sea spray as the ocean "bloom" evolved. The ability of the aerosol to uptake water and nucleate liquid cloud droplets, as well as its ice nucleation ability, experienced particularly significant changes. These changes did not correlate with changes in the size distribution of the aerosol, or in the chlorophyll concentration of the ocean water. These are the two main proxies that are currently used to attempt to predict how changes in ocean biology alter aerosol properties in global models.  Professor Sullivan found that those factors were not good proxies in this experiment, which may have implications for future predictions.

UPDATE: Check out an expanded article and photos on the CIT News page!