AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Ice Nucleating Particles at a Coastal Marine Boundary Layer Site: Correlations with Aerosol Type and Meteorological Conditions
RYAN H. MASON, Meng Si, Jixiao Li, Cédric Chou, Robin Dickie, Desiree Toom-Sauntry, Christopher Pöhlker, Jacqueline Yakobi-Hancock, Luis A. Ladino, Keith Jones, W. Richard Leaitch, Corinne L. Schiller, Jonathan Abbatt, J. Alex Huffman, Allan Bertram, University of British Columbia
Abstract Number: 488 Working Group: Aerosols, Clouds, and Climate
Abstract Ice nucleating particles (INPs) catalyze ice formation at temperatures above -37 °C, thereby affecting cloud microphysical properties and lifetime. In order to improve our understanding of how INPs affect climate, information on what aerosol particle types are acting as INPs in the atmosphere is needed. To determine the major sources of INPs active in the immersion mode at a coastal site in British Columbia, Canada, we investigated correlations between INP concentrations and both aerosol type and meteorological conditions. The concentrations of INPs active at freezing temperatures of -15 to -25 °C are strongly correlated with fluorescent bioparticle concentrations, and the size distribution of INPs is most consistent with the size distribution of fluorescent bioparticles. We therefore conclude that biological particles were likely the major source of ice nuclei between -15 and -25 °C. At -30 °C, concentrations of INPs and total aerosol particles ≥ 0.5 µm are also well correlated, suggesting that non-biological particles such as mineral dust may have had an important contribution to the population of INPs active at this temperature. Furthermore, we found that black carbon particles were unlikely to be a major source of INPs during the studied period. Finally, six empirical parameterizations of ice nucleation were tested to determine if they accurately predict the measured INP concentrations at our coastal site. None of the parameterizations selected are capable of predicting our INP concentrations, indicating that INP parameterizations that are appropriate for this complex environment still require development.