Ice nucleating particles in the atmosphere
Ice nucleating particles (INPs) play an important role in the formation of ice and mixed-phase clouds, which in turn impact the Earth's climate system and energy budget via precipitation efficiency and albedo. As water droplets cannot freeze homogeneously above -38C, ice formation in warmer clouds is initiated by INPs, which can range in composition from minerals to biological macromolecules. We are specifically interested in studying biogenic marine INPs, which are particularly impactful over remote regions of the ocean. INPs are rate in the atmosphere (1 in 106 particles) which has led to a poor understanding of both their chemical composition and the mechanism by which they nucleate ice. Our work focuses on immersion freezing, one of the pathways by which INPs can nucleate ice heterogeneously. In this mechanism, the particle takes up water to form a droplet prior to freezing. Using the micro-Raman spectrometer coupled with an environmental cell we are working to:
Identify and characterize marine INPs isolated during the 2019 NSF-CAICE SeaSCAPE campaign and develop model systems to be used in the laboratory
Investigate, through laboratory studies, the interactions of INPs with water at low temperature in increasingly complex environments with multiple organic and inorganic components
Determine the impact of heterogeneous chemistry with atmospheric oxidants (e.g., hydroxyl radicals, ozone, and nitric acid) on chemical composition as well as ice nucleation of individual INPs