The Utility of Fire Radiative Energy for Understanding Fuel Consumption due to Wildfire in Boreal Peatlands

Abstract:

Radiative energy from active fire has been found to correlate well with the amount of fuel consumed during the lifetime of a fire event. Fire radiative power (FRP) detected by sensors onboard MODIS satellites may therefore provide direct estimates of CO₂ emissions related to biomass burning. Less known is the ability of satellite data to detect active fire from predominantly smoldering burns in boreal peatlands. Boreal peatlands store a large amount of soil carbon that is likely to become increasingly vulnerable to wildfire as climate change lowers water tables and exposes C-rich peat to burning. In this study, we investigate the utility of fire radiative energy (FRE) to estimate fuel consumption associated with wildfire in 2004 in boreal peatlands in Alaska. FRE values are generally estimated from FRP retrieved at detected active fire locations and times by summing the FRP values multiplied by the time difference between acquisitions. One central issue in deriving reliable FRE estimates by such approach is the requirement for sufficient sampling of the FRP to capture spatiotemporal variability in the fire. Our preliminary analysis confirms that the detection of active fire in peatlands are indeed not spatially exhaustive and temporally continuous. Thus we are further investigating the fusion of instantaneous FRP from MODIS active fire detection with the MODIS burned area product to derive FRE estimates across the burned area. We are following a previously tested strategy for such fusion for temporal integration of instantaneous FRP to derive FRE and spatial extrapolation of FRE over the burned area. The FRE estimates are then related to ground-measured peatland burn depths across different wildfire locations. The results of this study will ultimately indicate the utility of MODIS fire products for providing reliable biomass burned estimates in boreal peatlands.