Faculty Research

Title

Ice Nucleation in Internally Mixed Ammonium Sulfate/Dicarboxylic Acid Particles

Document Type

Presentation

Publication Date

12-1-2003

Abstract

Recent studies have shown that tropospheric sulfate aerosols commonly contain 50 % by mass organic species. The influence of these organics on the chemical and physical properties of sulfate aerosols is not fully established. We have determined the ice nucleation temperatures for particles composed of eutonic mixtures of ammonium sulfate with a series of dicarboxylic acids. Measurements of the low temperature vapor pressures of the eutonic solutions were also made in order to develop a calibration curve to convert the freezing temperatures to ice saturation ratios. We find that for a given water activity, the freezing temperature is constant and is independent of the mole fraction of organic in solution. While this observation was predicted by {\it Koop et al.} [2000], the freezing temperatures observed in the present study are somewhat higher than those found in the emulsion studies used to develop the {\it Koop et al.} [2000] theory.

Comments

Publication Information.

Wise, M. E., R. M. Garland, and M. A. Tolbert, Ice nucleation in internally mixed ammonium sulfate/dicarboxylic acid particles, 2003 American Geophysical Union Meeting, San Francisco, CA, December 2003. Presentation A42E-07.