The Distribution in Time and Space of Savanna Fires in Burkina Faso as Determined from NOAA AVHRR Data

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Abstract
Geografisk Tidsskrift, Danish Journal of Geography 97: 86–97, 1997. Fires have significant effects on both biological diversity, nutrient cycling and emission of greenhouse gasses in the savanna zones of Africa. The meaning and characterization of the fire regimes of such areas are briefly discussed, and it is demonstrated that time series of NOAA AVHRR satellite images may be used for identifying active fires in Burkina Faso, and thus contribute to the characterization of the fire regime. Most fire activity in Burkina Faso is shown to take place in a brief period after the beginning of the dry season, defined as the date of a sharp increase in surface temperature. Based on an analysis of a small area over a short period the possibility of identifying fire scars, rather than active fires, is demonstrated. Furthermore it is shown that the number of pixels detected as active fire pixels may only be a small fraction of all pixels affected by fire. This has important implications for the use of fire detection methods for assessing the total area affected and the biomass burnt, something which is necessary in studies of gas emissions at a national scale as well as other studies of the impact of fires on the ecosystem. Finally, the future development of fire identification methods using Earth Observation data is discussed, and it is argued that development of fire models, using both Earth Observation and other information as inputs, will be required.