AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Probing the Source of Ice Nucleating Particles in Sea Spray Aerosol
PAUL DEMOTT, Christina S. McCluskey, Thomas Hill, Francesca Malfatti, Kimberly Prather, Alain Protat, Sonia Kreidenweis, Ruby Leung, Colorado State University
Abstract Number: 517 Working Group: Aerosols, Clouds, and Climate
Abstract The oceans provide a distinct source of ice nucleating particles (INPs) to the atmosphere in comparison to land sources (DeMott et al., 2015), one with INP active site density (cm-2) values, based on the sea spray aerosol (SSA) surface area distribution, that are more than 2 orders of magnitude below values documented for mineral and soil dusts from land. We present more recent data collected over Northern Hemisphere oceans which confirm these results. We will also present new measurements underway from collections in the Southern Ocean region, some of the first in nearly 40 years, and we will discuss implications for description in numerical modeling.
Discerning the composition of INPs from sea spray is challenging, which limits parameterization efforts. At sufficiently low temperatures, a real-time INP measurement such as a continuous flow diffusion chamber can be used to collect individual activated INPs. Such measurements indicate a variety of components in INPs from SSA at temperatures around -30C, including components of diatoms, exudates, and even fatty acids and lipids. Bulk INP collection and processing methods that are needed to quantify the low numbers active at modest cloud supercooling do not permit inspection of individual INPs, but indirect methods using application of heat, enzymes and other chemicals gives inferences to the nature of these particles or entities (e.g., they may be molecular in scale). Such investigations and an assessment of present understanding of the source of INPs in SSA will be presented.