Measurements of excess O-3, CO2, CO, CH4, C2H4, C2H2, HCN, NO, NH3, HCOOH,CH3COOH, HCHO, and CH3OH in 1997 Alaskan biomass burning plumes by airborne fourier transform infrared spectroscopy (AFTIR)

We used an airborne Fourier transform infrared spectrometer (AFTIR), couple d to a flow-through, air-sampling cell, on a King Air B-90 to make in situ trace gas measurements in isolated smoke plumes from four, large, boreal zo ne wildfires in interior Alaska during June 1997. AFTIR spectra acquired ne ar the source of the smoke plumes yielded excess mixing ratios for 13 of th e most common trace gases: water, carbon dioxide, carbon monoxide, methane, nitric oxide, formaldehyde, acetic acid, formic acid, methanol, ethylene, acetylene, ammonia and hydrogen cyanide. Emission ratios to carbon monoxide for formaldehyde, acetic acid, and methanol were 2.2 +/- 0.4%, 1.3 +/- 0.4 %, and 1.4 +/- 0.1%, respectively. For each oxygenated organic compound, a single linear equation fits our emission factors from Alaska, North Carolin a, and laboratory fires as a function of modified combustion efficiency (MC E). A linear equation for predicting the NH3/NOx emission ratio as a functi on of MCE fits our Alaskan AFTIR results and those from many other studies. AFTIR spectra collected in downwind smoke that had aged 2.2 +/- 1 hours in the upper, early plume yielded Delta O-3/Delta CO ratios of 7.9 +/- 2.4% r esulting from O-3 production rates of similar to 50 ppbv h(-1). The Delta N H3/Delta CO ratio in another plume decreased to 1/e of its initial value in similar to 2.5 hours. A set of average emission ratios and emission factor s for fires in Alaskan boreal forests is derived. We estimate that the 1997 Alaskan fires emitted 46 +/- 11 Tg of CO2.