Authors
Johana Romero (CIRES,NOAA/GSL), Ravan Ahmadov (NOAA/GSL), Jordan Schnell (CIRES,NOAA/GSL), Haiqin Li (CIRES,NOAA/GSL), Eric James (CIRES,NOAA/GSL), Gonzalo Ferrada (CIRES,NOAA/GSL), Sudheer Bhimireddy (CIRES,NOAA/GSL), Minsu Choi (CIRES,NOAA/GSL), Huiying Luo (NOAA/GSL,CIRA), Fangjun Li (GSCE South Dakota State University)
Abstract
During the record-breaking 2023 Canadian wildfire season, extreme drought exposed normally saturated peatlands and deep organic soils to high-severity combustion, revealing underestimations in the top-down emissions inventories used by flagship operational systems, such as HRRR-Smoke and the upcoming RRFS-Smoke. While these systems captured smoke transport pathways well, they underestimated smoke PM2.5 concentrations across North America.
Using high-resolution geospatial masks, we isolate regions dominated by organic soils and permanent wetlands and then update both the emission factors (EFs) and the biomass combustion coefficient (ð½), which is used to convert Fire Radiative Energy (FRE) into total biomass consumed. We test two ð½ formulations: one based on land-use-dependent values from published literature and another ecosystem-dependent ð½ derived by calibrating NOAAâs Regional ABI and VIIRS fire Emission product (RAVE) FRP against total biomass consumption estimates from the bottom-up Global Fire Emissions Database (GFED5.1).
Initial RRFS-Smoke simulations using these adjusted coefficients show a substantial increase in smoke emission estimates for fires influenced by organic-soil combustion. This update significantly reduces the low model biases observed during the 2023 season and brings model output into closer agreement with surface observations. These improvements address a low bias likely resulting from limitations in satellite-derived Fire Radiative Power (FRP) to detect weak smoldering signals from newly vulnerable carbon reservoirs, as well as retrieval uncertainty under the dense smoke conditions of 2023.