HR: 1340h
AN: A23B-1253    [Abstracts]
TI: Laboratory Investigation of the Relative Humidity Dependence of Light Extinction by Mixed Organic/Sulfate Particles
AU: * Beaver, M R
EM: melinda.beaver@colorado.edu
AF: Department of Chemistry and Biochemistry, University of Colorado, UCB 216, Boulder, CO 80309, United States
AU: * Beaver, M R
EM: melinda.beaver@colorado.edu
AF: CIRES, University of Colorado, UCB 216, Boulder, CO 80309, United States
AU: Baynard, T
EM: tahllee.baynard@noaa.gov
AF: NOAA Earth Systems Research Laboratory, Chemical Sciences Division, 325 Broadway, Boulder, CO 80305, United States
AU: Garland, R M
EM: garland@mpch-mainz.mpg.de
AF: Department of Chemistry and Biochemistry, University of Colorado, UCB 216, Boulder, CO 80309, United States
AU: Garland, R M
EM: garland@mpch-mainz.mpg.de
AF: CIRES, University of Colorado, UCB 216, Boulder, CO 80309, United States
AU: Garland, R M
EM: garland@mpch-mainz.mpg.de
AF: Biogeochemistry Department, Max Planck Institute for Chemistry, J.J.-Becherweg 27/29, Mainz, D-55128, Germany
AU: Hasenkopf, C
EM: christa.hasenkopf@colorado.edu
AF: CIRES, University of Colorado, UCB 216, Boulder, CO 80309, United States
AU: Hasenkopf, C
EM: christa.hasenkopf@colorado.edu
AF: Department of Atmospheric and Oceanic Sciences, University of Colorado, UCB 311, Boulder, CO 80309, United States
AU: Ravishankara, A R
EM: a.r.ravishankara@noaa.gov
AF: Department of Chemistry and Biochemistry, University of Colorado, UCB 216, Boulder, CO 80309, United States
AU: Ravishankara, A R
EM: a.r.ravishankara@noaa.gov
AF: NOAA Earth Systems Research Laboratory, Chemical Sciences Division, 325 Broadway, Boulder, CO 80305, United States
AU: Tolbert, M A
EM: margaret.tolbert@colorado.edu
AF: Department of Chemistry and Biochemistry, University of Colorado, UCB 216, Boulder, CO 80309, United States
AU: Tolbert, M A
EM: margaret.tolbert@colorado.edu
AF: CIRES, University of Colorado, UCB 216, Boulder, CO 80309, United States
AB: Light extinction by atmospheric particles is strongly dependent on the size, chemical composition, and water content of the aerosol. Since light extinction by particles directly impacts climate and visibility, direct measurement of extinction at various relative humidity (RH) conditions is needed. In this work, the optical growth factors, fRH_ext(80%RH, Dry) have been measured using cavity ring-down aerosol extinction spectroscopy for particles of varying organic/sulfate compositions. Specifically, slightly soluble, multifunctional aromatic compounds resulting from biomass burning have been investigated in this work. In general, the organic compounds studied exhibit much smaller optical growth than inorganic compounds such as ammonium sulfate. Also, a linear relationship between mass fraction organic and optical growth has been observed for most organic compounds studied. These results, an exception to the linear relationship, comparisons to growth factor measurements, Gf, refractive index determinations, and implications for climate calculations will be presented.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0360 Radiation: transmission and scattering
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting