Ice Nucleating Abilities of Coastal and Sea Surface Microlayer Aerosol Particles

Wednesday, 17 December 2014
Luis Ladino Moreno1, Theodore W Wilson2, Thomas Whale2, Benjamin John Murray3, Allan K Bertram4, M Breckels5, C Judd2, Ryan Mason6, Lisa Ann Miller7, Elena Polishchuk4, Corinne L Schiller8, Meng Si6, Jenny P S Wong9, Oliver Wurl10, Jacqueline Yakobi-Hancock1 and Jonathan Abbatt9, (1)University of Toronto, Chemistry, Toronto, ON, Canada, (2)University of Leeds, School of Earth and Environment, Leeds, United Kingdom, (3)University of Leeds, Leeds, United Kingdom, (4)University of British Columbia, Vancouver, BC, Canada, (5)University of Essex, Department of Biological Sciences, Colchester, United Kingdom, (6)University of British Columbia, chemistry, Vancouver, BC, Canada, (7)Institute of Ocean Sciences, Sidney, BC, Canada, (8)Environment Canada, Vancouver, BC, Canada, (9)University of Toronto, Toronto, ON, Canada, (10)Carl von Ossietzky Universit├Ąt Oldenburg, Institute for Chemistry and Biology of the Marine Environment, Wilhelmshaven, Germany
Marine aerosol particles are known to act as cloud condensation nuclei but their ice nucleating abilities are not well understood. As a result, we have investigated the potential for marine environments to act as a source of IN in two different locations, the North Pacific Ocean (PO) as part of the NETCARE (NETwork on Climate and Aerosols: Addressing key uncertainties in Remote Canadian Environments) project, and in the Arctic Ocean (AO) as part of the ACCACIA (Aerosol-Cloud Coupling and Climate Interactions in the Arctic) project. Ambient measurements conducted on the west coast of Vancouver Island (BC, Canada) showed that the IN concentrations at -40C and RHice of 139±2% varied from 0.2 L-1 to 3.3L-1 in the sub-micron size range. The correlations of IN concentrations with other atmospheric variables are used to infer their source. In addition, sea surface microlayer (SML) and subsurface waters (SSW) were collected in the PO and AO. The ice nucleating abilities of the PO and AO samples were studied via deposition nucleation and immersion freezing, respectively. Both data sets showed that the SML samples are better IN than the corresponding SSW. The ice nucleating abilities of the SML particles are comparable with those of mineral dust particles and bioaerosol particles which are known to be efficient IN. Heating and filtering experiments suggest that the high ice nucleating efficiency of the SML aerosol particles could be due to the presence of biological material. Our results indicate that the oceans need to be evaluated as an IN source for climate modeling.