HR: 14:55h
AN: A42E-06    [PDF]
TI: Water Uptake and Ice Nucleation of Particles containing Humic Materials
AU: * Brooks, S D
EM: sbrooks@lamar.colostate.edu
AF: Colorado State University, 1371 Atmospheric Science, Fort Collins, CO 80523-1371 United States
AU: DeMott, P J
EM: demott@atmos,colostate.edu
AF: Colorado State University, 1371 Atmospheric Science, Fort Collins, CO 80523-1371 United States
AU: Kreidenweis, S M
EM: sonia@atmos.colostate.edu
AF: Colorado State University, 1371 Atmospheric Science, Fort Collins, CO 80523-1371 United States
AB: Aerosols can influence cloud nucleation and thus, may alter climate. While much is known about sulfate aerosol, recent field studies show that atmospheric particles contain significant masses of organic species, such as dicarboxylic acids and larger polycarboxylic acids, resembling the humic materials in soil. The presence of these compounds may alter the water uptake and deliquescence characteristics of particles and their ability to form clouds. Using a humidified tandem differential mobility analyzer (HTDMA) we have measured the water uptake by pure humic material and by mixed humic material/ammonium sulfate particles as a function of relative humidity. We find that the water uptake behavior varies with the type and source of the humic material. In most cases, the pure humic materials take up very little water and the mixed organic/ammonium sulfate particles take up a reduced amount of water relative to pure ammonium sulfate. We have also measured the ice nucleation behavior of humic acid aerosols. Results of the water uptake and cloud nucleating ability of aerosols will be presented, and atmospheric implications discussed.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0320 Cloud physics and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting