Influence of timing and spatial extent of savanna fires in southern Africa on atmospheric emissions

Biomass burning is an important ecosystem process in southern Africa, with significant implications for regional and global atmospheric chemistry and biogeochemical cycles. In this paper, representative Landsat path-row scene locations, distributed over southern Africa, were used to quantify the area burned and to understand the coupled role of the timing and the extent of burning on regional emissions. The total area burned and the scar size distribution were found to vary between semi-arid and humid scenes and dry and average rainfall years. Analysis of images from the start and end of the burning season resulted in a modest underestimate of the annual area burned, as compared to using a monthly time-series approach. However, at the regional level the start/end method is likely to yield acceptable annual burned area estimates and total carbon dioxide estimates. On the other hand, combustion factors and emission factors vary sufficiently during the burning season to result in large errors in emission estimates of products of incomplete combustion, when using the start/end method. This study indicates that in southern Africa, the timing in addition to the extent of burning must be considered and that time-series satellite burned area products are needed to quantify pyrogenic emissions accurately