AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Factors Controlling the Emissions and Activity of Ice Nucleating Particles Released in Sea Spray Aerosol
PAUL DEMOTT, Gregory Schill, Christina S. McCluskey, Gavin Cornwell, Grant Deane, Francesca Malfatti, Mitchell Santander, Hashim Al-Mashat, Thomas Hill, Colorado State University
Abstract Number: 670 Working Group: Aerosols, Clouds, and Climate
Abstract Ice nucleating particles (INPs) from sea spray aerosol (SSA) are a distinct source to the atmosphere in comparison to land sources. The action of these INPs of biogenic origin, together with the action of the Wagener-Bergeron- Findeisen process, alter the optical properties, lifetime, and precipitation from mixed-phased clouds in similarly distinct ways in remote ocean regions. While progress has been made to indicate that marine INPs come both from seawater particulate organic carbon (POC) and dissolved organic carbon (DOC) pools (McCluskey et al., 2017, J. Atmos. Sci. 74, 151-166), less is known about the physical and chemical processes affecting their selective emissions.
In this work, we present results that examine the mechanisms controlling INP emissions in SSA. SSA was produced from a miniature Marine Aerosol Reference Tank (miniMART). Real and synthetic seawater were used, spiked with INPs of known activity, and real-time INP concentrations were monitored with a Continuous Flow Diffusion Chamber. Immersion freezing INP measurements of collected particles were also made. Pollen wash water (PWW) and Arizona Test Dust (ATD) were chosen to represent the two distinct size regimes of INP (POC larger, DOC smaller). Addition of isolated sea-surface microlayer to INP-spiked seawater affected INP emissions in both cases; PWW-INP emissions were enhanced and ATD-INP emissions decreased. Finally, the addition of the protein Bovine Serum Albunim (BSA) induced frothing at the air-seawater interface and selectively reduced the INP emissions of both PWW and ATD. BSA addition reduced the aerosol concentration by a factor of 2, but decreased INP emissions by over a factor of 100. Comprehensive data elucidating this selectivity mechanism, including jet versus film drop production, bubble-dynamics modeling, and aerosol chemical composition will be shown.