1121 / 2024-09-20 13:17:22

Impact of Phytoplankton Activity on the Ice Nucleation Potential of Marine Aerosols

Ice nucleation，Marine aerosol，Single particle analysis, CCSEM/EDX

Session 25 - IGAC-SOLAS: Chemistry and physics at surface ocean and lower atmosphere

Marine aerosols, as significant contributors to atmospheric particles, can act as ice-nucleating particles (INPs), influencing cloud formation and cloud microphysical properties, thereby indirectly affecting the global radiation balance. The physical and chemical properties of marine aerosols are influenced by phytoplankton activity in the ocean, which may impact their ice nucleation potential. In this study, we present heterogeneous ice nucleation and micro-spectroscopic characterization for particles generated by bubble busting during mesocosm experiments. The phytoplankton bloom during the experiment had chlorophyll-a concentrations comparable to natural conditions. We observed aerosol particles produced at different growth periods exhibit significant differences in composition and morphology, while their ice nucleation abilities remained similar. Two types of INPs were identified and analyzed including partially aged sea salt particles coated with organic material and fully aged sea salt particles, with the latter being enriched in INPs. Compared to particles without organic coating generated from subsurface seawater, the relative humidity with respect to ice of aerosol particles was 10%-20% lower, indicating that organic coating can promote the ice nucleating properties of marine aerosols. This study proposed parameterizations for the ice nucleating activity site density, heterogeneous nucleation rate coefficient, and contact angle of marine aerosols influenced by phytoplankton.