Small Fires, Big Impact: Evaluating Fire Emission Estimates in Southern Africa Using New Satellite Imagery of Burned Area and Carbon Monoxide

Abstract

Various fire emission estimates for southern Africa during 2019, derived with multiple burned area data sets with resolutions ranging from 500 to 20 m, are evaluated using satellite carbon monoxide (CO) observations. Southern African emissions derived from burned area generated by 20 m Sentinel-2 satellite imagery are up to 120% higher than other estimates because small fires are better detected with a higher-resolution satellite instrument. A comprehensive comparison between simulated and observed atmospheric CO indicates that the Sentinel-2 burned area data significantly improves emission estimates, with up to 15% reduction in CO concentration biases in comparison to emissions based on coarser resolution burned area data. We also found that the temporal lag between emissions and atmospheric CO concentrations during the peak fire month was related to atmospheric transport. These findings emphasize the importance of utilizing higher-resolution satellite instruments in accurately estimating emissions and understanding the impact of small fires on global climate.