Identification of Cloud-Nucleating and Ice-Nucleating Biological Aerosol Sources

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This project focuses on laboratory experiments to provide the quantitative data needed to understand and predict the impacts of marine emissions on cloud formation in the atmosphere. The primary objectives of this effort are: (1) Determine which phytoplankton groups are the most effective producers of aerosols; (2) Determine when in the bloom cycle of the phytoplankton the organisms are the most effective in producing aerosol; and (3) For the most effective aerosol producers, identify the specific components of the aerosol that are responsible for activating cloud formation.This project will provide fundamental information on the linkages between marine ecosystem structure and function and cloud formation in the atmosphere. Representative phytoplankton groups, including cyanobacteria, diatoms, and coccolithophores, will be grown in a large mesocosm tank Phytoplankton growth will be followed closely by measuring changes in the concentrations of chlorophyll. Aerosols will be generated from the surface water of the mesocosm to identify which organisms serve as the most effective generators of aerosol, cloud condensation nuclei (CCN), and ice nuclei (IN). A suite of biological and chemical techniques will be used to characterize the cloud-nucleating and ice-nucleating properties of the aerosol.This project will provide insight for field measurements in the real ocean. The researchers will perform additional CCN fractionation experiments during a different project that involves four cruises in the North Atlantic to take place in 2015-2020. Hence, the fractionation experiments conduct through this research will provide a direct comparison to field measurements.