Deactivation of ice nuclei due to atmospherically relevant surface coatings

Journal Article · Mon Nov 23 04:00:00 EST 2009 · Environmental Research Letters, 4(4):Art. No. 0044013

DOI:https://doi.org/10.1088/1748-9326/4/4/044013· OSTI ID:972949

Cziczo, Daniel J; Froyd, Karl D; Gallavardin, S J; Moehler, Ottmar; Benz, Stefan; Saathoff, Harald; Murphy, Daniel M

The ice nucleation characteristics of Arizona Test Dust (ATD) and illite clay, surrogates for atmospheric ice nuclei, have been determined at the Aerosol Interactions and Dynamics in the Atmosphere (AIDA) chamber located at the Research Center Karlsruhe in Germany. The objective of this research was to determine the effect of sulphuric acid and ammonium sulphate coatings on the ability of these mineral dust surrogates to nucleate ice in an environment where particles realistically compete for water vapor. Coated ATD particles required higher saturations at all investigated temperatures, from -20 to -45º C, than did identical uncoated particles. Freezing of coated particles often required saturations approaching those for the homogeneous freezing of aqueous solutions of the coating material alone. Less pronounced effects were found for illite although the presence of a coating consistently increased the saturation or decreased the temperature required for ice formation. Analysis of ice residue at the single particle level suggests that the first coated particles to freeze had thinner or incomplete coatings when compared to particles that froze later in the expansion. This observation highlights a need to verify coating properties since an assumption of homogeneity of a group of coated aerosol may be incorrect. The increase in saturation ratio for freezing suggests that gas-phase uptake of sulphates, a large fraction of which are due to anthropogenic emissions, will reduce the ice and mixed-phase cloud formation potential of atmospheric ice nuclei.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 972949
• Report Number(s): PNNL-SA-69059
• Journal Information: Environmental Research Letters, 4(4):Art. No. 0044013, Journal Name: Environmental Research Letters, 4(4):Art. No. 0044013 Journal Issue: 4 Vol. 4; ISSN 1748-9326
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AEROSOLS
AMMONIUM SULFATES
ATMOSPHERIC CHEMISTRY
CLOUDS
COATINGS
DEACTIVATION
DUSTS
ICE
ILLITE
NUCLEATION
SULFURIC ACID
SURFACE COATING