Uncertainty in fire emission factors and the impact on modeled
atmospheric CO and O3
Abstract
Fire emissions are an important component of global models, which help
to understand the influence of sources, transport and chemistry on
atmospheric composition. Global fire emission inventories can vary
substantially due to the assumptions made in the emission creation
process, including the defined vegetation type, fire detection, fuel
loading, fraction of vegetation burned and emissions factors. Here, we
focus on the uncertainty in emission factors and the resulting impact on
modeled composition. Our study uses the Community Atmosphere Model with
chemistry (CAM-chem) to model atmospheric composition for 2014, a year
chosen for the relatively quiet El Niño Southern Oscillation activity.
We focus on carbon monoxide (CO), a trace gas emitted from incomplete
combustion and also produced from secondary oxidation of volatile
organic compounds (VOCs). Fire is a major source of atmospheric CO and
VOCs. Modeled CO from four fire emission inventories (CMIP6/GFED4s,
QFED2.5, GFAS1.2 and FINN1.5) are compared after being implemented in
CAM-chem. Multiple sensitivity tests are performed based on CO and VOC
emission factor uncertainties. We compare model output in the 14 basis
regions defined by the Global Fire Emissions Database (GFED) team and
evaluate against CO observations from the Measurements of Pollution in
the Troposphere (MOPITT) satellite-based instrument. For some regions,
emission factor uncertainty spans the results found by using different
inventories. Finally, we use modeled ozone (O3) to briefly investigate
how emission factor uncertainty influences the atmospheric oxidative
environment. Overall, accounting for emission factor uncertainty when
modeling atmospheric chemistry can lend a range of uncertainty to
simulated results.