HR: 0800h
AN: A41D-0741    [Abstracts]
TI: Hygroscopic Growth Potential and Cloud Condensation Nuclei Activation of Mixed Aerosols
AU: * Aumann, E
EM: eaumann@stanford.edu
AF: Stanford University, Department of Geophysics 397 Panama Mall Mitchell Building, Room 360, Stanford, CA 94305, United States
AU: Rodriguez, L I
EM: luziro@stanford.edu
AF: Stanford University, Department of Geophysics 397 Panama Mall Mitchell Building, Room 360, Stanford, CA 94305, United States
AU: Cabrera, J
EM: jcabrera@stanford.edu
AF: Stanford University, Department of Geophysics 397 Panama Mall Mitchell Building, Room 360, Stanford, CA 94305, United States
AU: Tabazadeh, A
EM: azadeht@stanford.edu
AF: Stanford University, Department of Geophysics 397 Panama Mall Mitchell Building, Room 360, Stanford, CA 94305, United States
AB: Organic matter comprises a significant fraction of submicron aerosol mass in the atmosphere and it is often well mixed with inorganic components in solution. The water-soluble organic fraction in aerosol particles, known to be similar in structure to fulvic acid (FA), may affect the hygroscopic growth of inorganic aerosol particles. To determine the effect of organic matter on water uptake by sea salt and sulfate aerosols, the water vapor pressures of aqueous FA and mixed FA \ NaCl and FA \ (NH₄)₂SO₄ bulk solutions were measured using a vapor pressure apparatus. Water vapor pressures measured over mixed solutions were within the uncertainty limits of the values for pure inorganic solutions, suggesting that organic matter present in low concentrations cannot alter the hygroscopic growth of inorganic aerosols. We use a modified Köhler equation and FA surface tension measurements to further show that, contrary to previous studies, water-soluble organic matter may not lower the supersaturation required for inorganic particle activation into cloud droplets.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting