Abstract. Wildfires are a major source of air pollutants in the United States. Wildfire
smoke can trigger severe pollution episodes with substantial impacts on
public health. In addition to acute episodes, wildfires can have a marginal
effect on air quality at significant distances from the source, presenting
significant challenges to air regulators' efforts to meet National Ambient
Air Quality Standards. Improved emission estimates are needed to quantify the
contribution of wildfires to air pollution and thereby inform decision-making
activities related to the control and regulation of anthropogenic air
pollution sources. To address the need of air regulators and land managers for improved wildfire
emission estimates, we developed the Missoula Fire Lab Emission Inventory
(MFLEI), a retrospective, daily wildfire emission inventory for the
contiguous United States (CONUS). MFLEI was produced using multiple datasets
of fire activity and burned area, a newly developed wildland fuels map and an
updated emission factor database. Daily burned area is based on a combination
of Monitoring Trends in Burn Severity (MTBS) data, Moderate Resolution
Imaging Spectroradiometer (MODIS) burned area and active fire detection
products, incident fire perimeters, and a spatial wildfire occurrence
database. The fuel type classification map is a merger of a national forest
type map, produced by the USDA Forest Service (USFS) Forest Inventory and
Analysis (FIA) program and the Geospatial Technology and Applications Center
(GTAC), with a shrub and grassland vegetation map developed by the USFS
Missoula Forestry Sciences Laboratory. Forest fuel loading is from a fuel
classification developed from a large set (> 26 000 sites) of FIA surface
fuel measurements. Herbaceous fuel loading is estimated using site-specific
parameters with the Normalized Difference Vegetation Index from MODIS. Shrub
fuel loading is quantified by applying numerous allometric equations linking
stand structure and composition to biomass and fuels, with the structure and
composition data derived from geospatial data layers of the LANDFIRE project.
MFLEI provides estimates of CONUS daily wildfire burned area, fuel
consumption, and pollutant emissions at a 250 m × 250 m resolution
for 2003–2015. A spatially aggregated emission product
(10 km × 10 km, 1 day) with uncertainty estimates is included to
provide a representation of emission uncertainties at a spatial scale
pertinent to air quality modeling. MFLEI will be updated, with recent years,
as the MTBS burned area product becomes available. The data associated with
this article can be found at https://doi.org/10.2737/RDS-2017-0039 (Urbanski et al., 2017).