HR: 14:55h
AN: A43E-06    [Abstracts]
TI: Variability of Physical and Optical Properties of Particles Emitted from Combustion of Wildland Fuels
AU: * Chen, L A
EM: antony@dri.edu
AF: Division of Atmospheric Sciences, Desert Research Institute , 2215 Raggio Parkway, Reno, NV 89512 United States
AU: Moosmller, H
EM: hansm@dri.edu
AF: Division of Atmospheric Sciences, Desert Research Institute , 2215 Raggio Parkway, Reno, NV 89512 United States
AU: Arnott, W P
EM: pat@dri.edu
AF: Division of Atmospheric Sciences, Desert Research Institute , 2215 Raggio Parkway, Reno, NV 89512 United States
AU: Chow, J C
EM: judyc@dri.edu
AF: Division of Atmospheric Sciences, Desert Research Institute , 2215 Raggio Parkway, Reno, NV 89512 United States
AU: Watson, J G
EM: johnw@dri.edu
AF: Division of Atmospheric Sciences, Desert Research Institute , 2215 Raggio Parkway, Reno, NV 89512 United States
AU: Susott, R
EM: rsusott@fs.fed.us
AF: Fire Sciences Laboratory, 5775 W. Hwy. 10, Missoula, MT 59802 United States
AU: Kovalev, V
EM: vkovalev@fs.fed.us
AF: Fire Sciences Laboratory, 5775 W. Hwy. 10, Missoula, MT 59802 United States
AU: Hao, W
EM: whao@fs.fed.us
AF: Fire Sciences Laboratory, 5775 W. Hwy. 10, Missoula, MT 59802 United States
AB: Emissions from wildland fires make an important contribution to aerosol radiative forcing. The estimation of this forcing is limited not only by uncertain emission factors and activity levels but also by uncertain optical properties of the emitted particles. To better characterize the optical properties of particle emissions from wildland fuels, in-situ measurements of aerosol light absorption (532 and 1047 nm photoacoustic instrument), scattering (TSI, Radiance and DRI nephelometers), and extinction coefficients (cavity enhanced detection instrument) were taken on emissions from burning several wildland fuels under laboratory controlled conditions. Fuels used include Ponderosa pine needles, White pine needles, Ponderosa pine wood, Sagebrush, Poplar wood, grasses, and Tundra cores. Substantial variability was found in particle single scattering albedo as a function of fuel type, combustion conditions, and combustion stage. Ponderosa pine wood combustion produces the lowest single scattering albedo of 0.3 - 0.4 during the flaming phase, approximating the reported values for pure elemental carbon (EC); during the smoldering phase a single scattering albedo of $>$ 0.97 is measured. Fine particulate mass was measured by gravimetery and elemental carbon/organic carbon (OC) were determined by four different thermal/optical protocols from concurrent time-integrated filter samples. The observed single scattering albedo generally decreases with increasing EC/OC ratios for all analysis protocols, with the mass absorption efficiency of EC ranging from 3.7 to 14.2 m$^{2}$/g. An aerosol optical model using measured size distributions and commonly modeled refractive indexes and mixing schemes for OC and EC demonstrates agreements with the measured particle optical properties at various degrees. The natural and artificial variability in the measurement of wildland fire smoke lead to biases in the current radiative forcing estimates.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0322 Constituent sources and sinks
DE: 0345 Pollution--urban and regional (0305)
DE: 0365 Troposphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting