HR: 1340h
AN: A33B-0881    [Abstracts]
TI: Instrument Development for Single Scattering Albedo Measurements of Black Carbon Aerosols
AU: * Sanford, T J
EM: todd.j.sanford@noaa.gov
AF: Aeronomy Laboratory, National Oceanic and Atmospheric Administration, 325 Broadway, 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
A33B-0881 AF: Aeronomy Laboratory, National Oceanic and Atmospheric Administration, 325 Broadway, Boulder, CO 80305 United States
AU: Thomson, D S
A33B-0881 AF: Aeronomy Laboratory, National Oceanic and Atmospheric Administration, 325 Broadway, Boulder, CO 80305 United States
AU: Thomson, D S
A33B-0881 AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
AU: Richard, E C
A33B-0881 AF: Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovation Drive, Boulder, CO 80303 United States
AU: Fox, R W
A33B-0881 AF: National Institute of Standards and Technology, 325 Broadway, Boulder, CO 80305 United States
AB: The optical properties of aerosols are critically important in the determination of the radiative forcings of these aerosols in the atmosphere. An especially important case is the amount of light scattered and the amount of light absorbed by black carbon aerosols. The radiative forcing of the aerosols can then be determined from the single scattering albedo, which is defined as the ratio of scattering to extinction (extinction = scattering + absorption). We are developing an instrument to measure the albedo of single particles. It consists of a diode laser frequency locked to a triangular, ring cavity into which the particles are introduced in the center of one side of the triangle. The extinction is obtained from the measurement of the cavity ringdown times and the total scattered light is measured in a spherical/ellipsoidal scattering cell. The instrument allows for simultaneous measurement of scattering and extinction, which leads to the cancellation of several important sources of error. Also, the amounts of forward and backward scattering can be individually resolved from the total scattering. Measurement of the forward scattering allows for more accurate size determination of the particles and the relationship of backward scattering to extinction is important to lidars. Initial characterization of the instrument is carried out on pure scattering polystyrene latex spheres of known diameters with the ultimate goal of the development of the instrument for field studies.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005