Global biomass burning fuel consumption and emissions at 500 m spatial resolution based on the Global Fire Emissions Database (GFED)

[摘要] In fire emission models, the spatial resolution of boththe modelling framework and the satellite data used to quantify burned areacan have considerable impact on emission estimates. Consideration of thissensitivity is especially important in areas with heterogeneous land coverand fire regimes and when constraining model output with fieldmeasurements. We developed a global fire emissions model with a spatialresolution of 500 m using MODerate resolution Imaging Spectroradiometer(MODIS) data. To accommodate this spatial resolution, our model is based ona simplified version of the Global Fire Emissions Database (GFED) modellingframework. Tree mortality as a result of fire, i.e. fire-related forestloss, was modelled based on the overlap between 30 m forest loss data andMODIS burned area and active fire detections. Using this new 500 m model, wecalculated global average carbon emissions from fire of 2.1±0.2 ( ±1 σ interannual variability, IAV) Pg C yr −1 during2002–2020. Fire-related forest loss accounted for 2.6±0.7  %(uncertainty range =1.9  %–3.3 %) of global burned area and 24±6  % (uncertainty range =16  %–31 %) of emissions, indicating that fuelconsumption in forest fires is an order of magnitude higher than the globalaverage. Emissions from the combustion of soil organic carbon (SOC) in theboreal region and tropical peatlands accounted for 13±4  % ofglobal emissions. Our global fire emissions estimate was higher than the 1.5 Pg C yr −1 from GFED4 and similar to 2.1 Pg C yr −1 from GFED4s.Even though GFED4s included more burned area by accounting for small firesundetected by the MODIS burned area mapping algorithm, our emissions weresimilar to GFED4s due to higher average fuel consumption. The globaldifference in fuel consumption could mainly be explained by higher SOCemissions from the boreal region as constrained by additional measurements.The higher resolution of the 500 m model also contributed to the differenceby improving the simulation of landscape heterogeneity and reducing thescale mismatch in comparing field measurements to model grid cell averagesduring model calibration. Furthermore, the fire-related forest lossalgorithm introduced in our model led to more accurate and widespreadestimation of high-fuel-consumption burned area. Recent advances in burnedarea detection at resolutions of 30 m and finer show a substantial amount ofburned area that remains undetected with 500 m sensors, suggesting thatglobal carbon emissions from fire are likely higher than our 500 mestimates. The ability to model fire emissions at 500 m resolution providesa framework for further improvements with the development of newsatellite-based estimates of fuels, burned area, and fire behaviour, for usein the next generation of GFED.

[学科分类] 土木及结构工程学