Abstract. Recent increases in boreal forest burned area, which have
been linked with climate warming, highlight the need to better understand
the composition of wildfire emissions and their atmospheric impacts. Here we
quantified emission factors for CO and CH4 from a massive regional fire
complex in interior Alaska during the summer of 2015 using continuous
high-resolution trace gas observations from the Carbon in Arctic Reservoirs
Vulnerability Experiment (CRV) tower in Fox, Alaska. Averaged over the 2015
fire season, the mean CO / CO2 emission ratio was 0.142 ± 0.051, and
the mean CO emission factor was 127 ± 40 g kg−1 dry biomass
burned. The CO / CO2 emission ratio was about 39 % higher than the mean
of previous estimates derived from aircraft sampling of wildfires from
boreal North America. The mean CH4 / CO2 emission ratio was 0.010 ± 0.004, and the CH4 emission factor was 5.3 ± 1.8 g kg−1 dry biomass burned, which are consistent with the mean of previous
reports. CO and CH4 emission ratios varied in synchrony, with higher
CH4 emission factors observed during periods with lower modified
combustion efficiency (MCE). By coupling a fire emissions inventory with an
atmospheric model, we identified at least 34 individual fires that
contributed to trace gas variations measured at the CRV tower, representing
a sample size that is nearly the same as the total number of boreal fires
measured in all previous field campaigns. The model also indicated that
typical mean transit times between trace gas emission within a fire
perimeter and tower measurement were 1–3 d, indicating that the time
series sampled combustion across day and night burning phases. The high CO
emission ratio estimates reported here provide evidence for a prominent role
of smoldering combustion and illustrate the importance of continuously
sampling fires across time-varying environmental conditions that are
representative of a fire season.
Development of a CO2 emission factor in Korea from sub-bituminous coal by the classification method
