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Evolution of Gases and Particles from a Savanna Fire in South AfricaAirborne measurements of particles and gases fiom a 1000-ha savanna fire in South Africa are presented. These measurements represent the most extensive data set reported on the aging of biomass smoke. The measurements include total concentrations of particles (CN), particle sizes, particulate organic carbon and black carbon, light-scattering coefficients, downwelling UV fluxes, and mixing ratios for 42 trace gases and 7 particulate species. The ratios of excess nitrate, ozone, and gaseous acetic acid to excess CO increased significantly as the smoke aged over approximately 40-45 min, indicating that these species were formed by photochemistry in the plume. For 17 other species, the excess mixing ratio normalized by the excess mixing ratio of CO decreased significantly with ' smoke age. The relative rates of decrease for a number of chemical species imply that the average OH concentration in the plume was approximately 1.7 x l0(exp 7) molecules /cubic centimeter. Excess CN, normalized by excess CO, decreased rapidly during the first approximately 5 min of aging, probably due to coagulation, and then increased, probably due to gas-to-particle conversion. The CO-normalized concentrations of particles < 1.5 microns in diameter decreased, and particles >1.5 micron diameter increased, with smoke age. The spectral depletion of solar radiation by the smoke is depicted. The downwelling UV flux near the vertical center of the plume was about two-thirds of that near the top of the plume.
Document ID
20050177224
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Hobbs, Peter V.
(Washington Univ. Seattle, WA, United States)
Sinha, Parikhit
(Washington Univ. Seattle, WA, United States)
Yokelson, Robert J.
(Montana Univ. Missoula, MT, United States)
Christian, Ted J.
(Montana Univ. Missoula, MT, United States)
Blake, Donald R.
(California Univ. Irvine, CA, United States)
Gao, Song
(Washington Univ. Seattle, WA, United States)
Kirchstetter, Thomas W.
(California Univ., Lawrence Berkeley National Lab. Berkeley, CA, United States)
Novakov, Tica
(California Univ., Lawrence Berkeley National Lab. Berkeley, CA, United States)
Pilewskie, Peter
(NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
August 23, 2013
Publication Date
January 1, 2003
Publication Information
Publication: Journal of Geophysical Research
Publisher: American Geophysical Union
Volume: 108
Issue: D13
ISSN: 0148-0227
Subject Category
Environment Pollution
Funding Number(s)
CONTRACT_GRANT: NAG5-9022
Distribution Limits
Public
Copyright
Other

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