A Look at Amazon Basin Seasonal Dynamics with the Biophysical ...

The Emissions From Savanna Fires, Domestic Biofuel Use, and ResidualSmoldering Combustion, and the Effects of Aging and Cloud-Processing on SmokeDuring SAFARI 2000R.J. Yokelson, I.T. Bertschi, and T.J. Christian.Department of Chemistry, University of Montana, Missoula, MT, 59812 USAbyok@selway.umt.eduP.V. HobbsUniversity of Washington, Department of Atmospheric Sciences, Seattle WAD.E. Ward and W.M. HaoU. S. Department of Agriculture Forest Service, Fire Sciences Laboratory, Missoula, MTAbstract. We carried out 2 campaigns in southern African during 2000. An airborneFTIR (AFTIR) measured the trace gases emitted by savanna fires and characterizedregional haze. A ground-based open-path FTIR measured trace gases emitted from theproduction and use of biofuels and smoldering combustion in wooded savannas. FTIRquantifies the stable and reactive trace gases present above several ppb. We measuredvertical profiles above instrumented ground sites and below TERRA/ER 2 . The mainspecies emitted by savanna fires were (in order of abundance) H 2 O, CO 2 , CO, CH 4 , NO 2 ,NO, C 2 H 4 , CH 3 COOH, HCHO, CH 3 OH, HCN, NH 3 , HCOOH, and C 2 H 2 . These are thefirst quantitative measurements of 6 of the 15 major compounds emitted by these fires(which also featured extensive fuel characterization). The oxygenated organic compounds(OVOC) dominate the initial emissions and have large effects on tropospheric chemistry.The emission factor (EF) for HCN, a tracer for savanna fires, was ~ 20 times the valuemeasured for Australian savanna fires. ∆O 3 /∆CO and ∆CH 3 COOH/∆CO increased to 9%in < 1 hr downwind from fires making them larger than ∆CH 4 /∆CO. Cloud processing ofsmoke removed CH 3 OH, NH 3 , acetic acid, SO 2 , and NO 2 , but increased HCHO and NO.Intense multiphase chemistry likely occurs in smoke-impacted clouds. Domestic biomassfuels (biofuels) are the second largest type of global biomass burning. We made the first,tropical, in-situ measurements of a broad suite of trace gases emitted by domestic woodand charcoal fires and a charcoal kiln. The 18 major trace gases were quantifiedincluding: CO 2 , CO, NO x , CH 4 , NMHC, OVOC, and NH 3 . OVOC accounted for 70-80%of the organic emissions. In Zambia, biofuels contribute larger annual emissions of CH 4 ,CH 3 OH, C 2 H 2 , acetic acid, HCHO, and NH 3 than savanna fires by factors of 5.1, 3.9, 2.7,2.4, 2.2, and 2.0, respectively. Residual smoldering combustion (RSC) is biomasscombustion that produces emissions that are not lofted by strong fire-induced convection.RSC is a globally significant trace gas source. We measured the first EF for RSC in ourlaboratory and a wooded savanna in Zambia. The major trace gases include CO 2 , CO,CH 4 , C 2 H 6 , C 2 H 4 , C 2 H 2 , C 3 H 6 , HCHO, CH 3 OH, acetic acid, formic acid, glycolaldehyde,phenol, furan, NH 3 , and HCN. The wooded savanna fire EFCH 4 increased by a factor of2.5 when the 10% of fuel consumption by RSC was factored in. More measurements offuel consumption and EF for RSC would improve estimates of biomass burningemissions.