HR: 0800h
AN: A41D-0732    [Abstracts]
TI: Albedo Measurements and Optical Sizing for Single Aerosol Particles
AU: * Sanford, T J
EM: todd.j.sanford@noaa.gov
AF: Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, United States
AU: * Sanford, T J
EM: todd.j.sanford@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, United States
AU: Murphy, D M
AF: Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, United States
AU: Thomson, D S
AF: Earth System Research Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, United States
AU: Thomson, D S
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309, United States
AU: Fox, R W
AF: National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305, United States
AB: Atmospheric particles affect the radiative balance of the Earth by their interactions with solar and terrestrial radiation. A useful metric for this effect is the single-scattering albedo, which is the ratio of scattering to extinction. Black carbon is a climatically important class of atmospheric particles due to its appreciable absorption of radiation. The mixing states of the black carbon particles affect the amount of absorption and thus the albedo values, however this information is absent in bulk measurements. To address this issue an instrument has been developed to carry out scattering and extinction measurements simultaneously on single atmospheric particles. Particles are introduced into a frequency stabilized, diode pumped ring laser cavity. The light scattered by the particles is collected by a spherical/ellipsoidal scattering cell. Also, light scattered in the forward and backward directions is collected in independent measurement channels. The ratio of the forward scattering to total scattering is used for optical sizing of the particles. The extinction due to the particles is obtained by measuring the depletion in the cavity transmission signal. Both the scattering and extinction measurements are triggered by individual particles and are combined for a measure of the albedo for each particle. Characterization of the instrument has been carried out with laboratory-generated particles of known sizes and optical properties with modifications being made for eventual field deployment.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0360 Radiation: transmission and scattering
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting