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Trace Gas Measurements in Nascent, Aged and Cloud-processed Smoke from Africa Savanna Fires by Airborne Fourier Transform Infrared Spectroscopy (AFTIR)We measured stable and reactive trace gases with an airborne Fourier transform infrared spectrometer (AFTIR) on the University of Washington Convair-580 research aircraft in August/September 2000 during the SAFARI 2000 dry season campaign in Southern Africa. The measurements included vertical profiles of C02, CO, H20, and CH4 up to 5.5 km on six occasions above instrumented ground sites and below the TERRA satellite and ER-2 high-flying research aircraft. We also measured the trace gas emissions from 10 African savanna fires. Five of these fires featured extensive ground-based fuel characterization, and two were in the humid savanna ecosystem that accounts for most African biomass burning. The major constituents we detected in nascent CH3OOH, HCHO, CH30H, HCN, NH3, HCOOH, and C2H2. These are the first quantitative measurements of the initial emissions of oxygenated volatile organic compounds (OVOC), NH3, and HCN from African savanna fires. On average, we measured 5.3 g/kg of OVOC and 3.6 g/kg of hydrocarbons (including CH4) in the initial emissions from the fires. Thus, the OVOC will have profound, largely unexplored effects on tropical tropospheric chemistry. The HCN emission factor was only weakly dependent on fire type; the average value (0.53 g/kg) is about 20 times that of a previous recommendation. HCN may be useful as a tracer for savanna fires. Delta O3/Delta CO and Delta CH3COO/Delta CO increased to as much as 9% in <1 h of photochemical processing downwind of fires. Direct measurements showed that cloud processing of smoke greatly reduced CH30H, NH3, CH3COOH, SO2, and NO2 levels, but significantly increased HCHO and NO.
Document ID
20050177027
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Yokelson, Robert J.
(Montana Univ. Missoula, MT, United States)
Bertschi, Isaac T.
(Montana Univ. Missoula, MT, United States)
Christian, Ted J.
(Montana Univ. Missoula, MT, United States)
Hobbs, Peter V.
(Washington Univ. Seattle, WA, United States)
Ward, Darold E.
(Forest Service Missoula, MT, United States)
Hao, Wei Min
(Forest Service Missoula, MT, 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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