Improving Global Burned Area Estimates by Merging High and Moderate Resolution Satellite Fire Products
Abstract
Most existing global-scale burned area products are generated by applying change detection algorithms to daily surface reflectance time series from moderate resolution spectroradiometers. Because of the relatively coarse spatial resolution of these sensors, fires with small sizes and low to intermediate levels of burn severity often go undetected in these products. At the same time, the prevalence of unburned islands in locations where fire was detected in moderate resolution products have been difficult to characterize, resulting in an overestimation of burned area in some areas. High resolution data from spectroradiometers onboard the Landsat or Sentinel-2 are available at lower temporal frequency but can be used to quantify omission and commission errors under persistent cloud free conditions. Here we use high-resolution data to correct for omission and commission errors of the MODIS collection 6 burned area product. We corrected omission errors using a set of scalers based on the ratio of the high-resolution burned area to the area of MODIS active fire detections outside of MODIS burned area perimeters. Commission errors are corrected using scalers based on spatiotemporally aligned burned areas from MODIS and high-resolution sensors. To account for limited availability of high-resolution burned area data, we create a parameterized look-up table of omission and commission scalers as a function of latitudinal band, land cover type, and fractional tree cover. We then derive a new version of Global Fire Emissions Database (GFED) burned area product using the MODIS 500m burned area and 1-km active fire data. Averaged over 2001-2020, global burned area from our approach is more than 50% higher than the MODIS collection 6 burned area product. On average, adjustments for omission errors are larger in tropical forests and woody savannas than in other biomes. The new burned area time series highlight how burned area continues to decline in tropical savanna biomes, whereas burned area in extratropical forests shows a positive trend that is, in part, driven by recent mega-fire events in Australia, the western United States, and boreal forests of North America and Eurasia.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.A55S1676C