HR: 16:00h
AN: A14B-01    [Abstracts]
TI: Physical, Chemical and Optical Properties of Aerosol over North America: Airborne Observations from INTEX-NA
AU: * Clarke, A D
EM: tclarke@soest.hawaii.edu
AF: University of Hawaii, 1000 Pope Rd., Honolulu, HI 96822
AU: Howell, S G
EM: showell@soest.hawaii.edu
AF: University of Hawaii, 1000 Pope Rd., Honolulu, HI 96822
AU: McNaughton, C S
EM: csmcnaug@hawaii.edu
AF: University of Hawaii, 1000 Pope Rd., Honolulu, HI 96822
AU: Kahn, R
EM: Ralph.Kahn@jpl.nasa.gov
AF: Nasa Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109
AU: Russell, P B
EM: Philip.B.Russell@nasa.gov
AF: NASA Ames Research Center, MS 245-5, Moffet Field, CA 94035
AU: Livingston, J M
EM: jlivingston@mail.arc.nasa.gov
AF: SRI International, 333 Ravenswood Ave., Menlo Park, CA 94025
AU: Schmidt, B
EM: bschimd@mail.arc.nasa.gov
AF: BAERI, MS 100, Ventura, CA 94035
AU: Redeman, J
EM: jredemann@mail.arc.nasa.gov
AF: BAERI, MS 100, Ventura, CA 94035
AU: Anderson, B
EM: b.e.anderson@larc.nasa.gov
AF: NASA Langley Research Center, MS 483, Hampton, VA 23681
AB: During INTEX-NA the NASA DC-8 sampled aerosols across North America and over the adjoining oceans. A wide variety of aerosol plumes were detected from numerous sources. We measured particle diameter and volatility between 10 and 10,000 nm, light scattering and absorption at 450, 550, and 700 nm, and change in scattering with humidity (f(RH)). Particle size distrubutions and volatility in biomass burning plumes were quite distinct from industrial and urban plumes. Biomass had relatively large median diameters (300 nm) and large refractory components (often 200 nm). In contrast, urban pollution plumes had much smaller and more variable refractory components, reflecting a variety of sources. Median particle size was much smaller (100-200 nm) and varied with the age of the plume. These differences were closely tied to optical and chemical properties of the plumes. Absorption Angstrom exponents were high (1.2 to 1.7) for biomass and lower (0.3 to 1.2) in pollution. Scattering Angstrom exponents (1.0 to 1.7), and f(RH) (1.1 to 1.3 from 40 to 85% RH) were lower in biomass plumes than in the other types of pollution plumes (values of 1.7 to 2.5 for scattering Angstrom and 1.5 to 2.5 for f(RH)). The biomass particles also had a lower percentage of soluble inorganic ion mass than urban pollution plumes. High altitude biomass burning plumes over low altitude urban pollution present a challenging situation for satellite measurements of aerosol optical depth. Two extensive intercomparisons of in-situ optical properties with directly-measured optical depth gave good agreement, but satellite optical depths were significantly higher for reasons that are as yet unclear.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0360 Radiation: transmission and scattering
DE: 0365 Troposphere: composition and chemistry
DE: 0368 Troposphere: constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005