Defining a fire year for reporting and analysis of global interannual fire variability

The interannual variability of fire activity has been studied without an explicit investigation of a suitable starting month for yearly calculations. Sensitivity analysis of 37 months of global MODIS active fire detections indicates that a 1-month change in the start of the fire year definition can lead, in the worst case, to a difference of over 6% and over 45% in global and subcontinental scale annual fire totals, respectively. Optimal starting months for analyses of global and subcontinental fire interannual variability are described. The research indicates that a fire year starting in March provides an optimal definition for annual global fire activity.