Characterising Fire Hazard from Temporal Sequences of Thermal Infrared Modis Measurements

The objective of the present research was the characterisation of fire hazard using temporal sequences of land surface temperature (LST) derived from Terra-MODIS measurements. The investigation was based on a complete sequence of MODIS LST data from 2000 to 2006 on Campania (Italy) and on a dataset of fires officially recorded in the area in the same period. Missing and/or cloudy LST data were reconstructed by means of the HANTS (Harmonic ANalysis of Time Series) algorithm applied to annual sequences of daily observations. The coefficients of the Fourier analysis were then assessed against spatial patterns of fire occurrence. HANTS algorithm was also used on the complete LST dataset to construct daily reference temperature maps against which to evaluate temperature anomalies and cumulated temperature anomalies. Results show that fires tend to occur in areas characterised by specific values of several Fourier coefficients with high significance, and to avoid the other areas. The amplitude of the second harmonic is the only Fourier coefficient dictating mean fire size. The mean fire size and the proportion of large fires correlate with both daily and cumulated thermal anomalies. However, the dynamic range of the predictions from cumulated anomalies is much larger, and thus maps of the latter are more effective in predicting fire hazard.