Emissions and Characteristics of Ice Nucleating Particles Associated with Laboratory Generated Nascent Sea Spray Aerosol

Thursday, 17 December 2015
Poster Hall (Moscone South)
Christina S. McCluskey1, Thomas Christopher James Hill1, Charlotte Beall2, Camille Marissa Sultana2, Kathryn Moore2, Gavin Cornwell2, Chris Lee2, Hashim Al-Mashat2, Olga Laskina3, Jonathan Trueblood3, Vicki H Grassian3, Kimberly A Prather2, Sonia M Kreidenweis1 and Paul J DeMott1, (1)Colorado State University, Fort Collins, CO, United States, (2)University of California San Diego, La Jolla, CA, United States, (3)University of Iowa, Iowa City, IA, United States
Accurate emission rates and activity spectra of atmospheric ice nucleating particles (INPs) are required for proper representation of aerosol-cloud interactions in atmospheric modeling studies. However, few investigations have quantified or characterized oceanic INP emissions. In conjunction with the Center for Aerosol Impacts on the Climate and the Environment, we have directly measured changes in INP emissions and properties of INPs from nascent sea spray aerosol (SSA) through the evolution of phytoplankton blooms.

Multiple offline and online instruments were used to monitor aerosol chemistry and size, and bulk water characteristics during two phytoplankton bloom experiments. Two methods were utilized to monitor the number concentrations of INPs from 0 to -34 °C: The online CSU continuous flow diffusion chamber (CFDC) and collections processed offline using the CSU ice spectrometer. Single particle analyses were performed on ice crystal residuals downstream of the CFDC, presumed to be INPs, via scanning transmission electron microscopy (STEM) and Raman microspectroscopy.

Preliminary results indicate that laboratory-generated nascent SSA corresponds to number concentrations of INPs that are generally consistent with open ocean regions, based on current knowledge. STEM analyses revealed that the sizes of ice crystal residuals that were associated with nascent SSA ranged from 0.3 to 2.5 μm. Raman microspectroscopy analysis of 1 μm sized residuals found a variety of INP identities, including long chain organics, diatom fragments and polysaccharides. Our data suggest that biological processes play a significant role in ocean INP emissions by generating the species and compounds that were identified during these studies.