Difference in observation of Indonesian fire by DMSP-OLS and NOAA-AVHRR
Results and Discussion
Figure 2 shows "hot spots" detected by NOAA-AVHRR and "fire flares" detected by DMSP-OLS on 31 October. The figure suggests that more forest fires could be detected by DMSP-OLS as "fire flares" than by NOAA-AVHRR as "hot spots". The "fire flares" detected by DMSP-OLS found spatially broad, which is presumably due to scattering of scattering of lights by prevailing thin haze. Table 1 shows the dates when those fires were detected by NOAA-AVHRR or by DMSP-OLS in the study area. The "hot spots" detected by NOAA-AVHRR on 3 November serve as reference for table 1.
Figure 2 Hot spot detected NOAA-AVHRR & Fire detected by DMSP-OLS
Table 1 The dates when those fires were detected by
NOAA-AVHRR or by DMSP-OLS in the study area
A number of forest fires were detected initially as "fire flares" by DMSP-OLS, much sooner than being detected as "hot sports" by NOAA-AVHRR. It was presumably because NOAA-AVHRR often fails to detect "hot spots" at the onset of a fire owing to haze, while DMSP-OLS could detect "first flash" of a fire flare flawlessly. Figure 3 shows "hot spots" detected by NOAA-AVHRR, "fire flares" detected by DMSP-OS on 3 November. Some fires failed to be detected as "fire flares" by DMSP-OLS, while they were detected as "hot spots" by preat, it sounds likely that NOAA-AVHRR detected forest fires as hot spots, even in "smoldering phase" of forest fires, which is particular to the prevailing peatlands in the study area.
Figure 3 Hot spot detected NOAA-AVHRR & Fire detected by DMSP-OLS
Conclusion
The multiple sensor approach was proved much more useful in monitoring the progress of a forest fire in Indonesia throughout its burning process vis-à-vis monitoring the same fire only with a single sensor. Further efforts are still required in the following aspects : (a) Development of a methodology to pinpoint a forest fire with DMSP-OLS, which has coarser resolution than NOAA-AVHRR (b) Identification of the reason why DMSP-OLS can detect a forest fire much sooner than NOAA-AVHRR. In other words, it should be examined why "fire flares" may be observed with DMSP-OLS much sooner than NOAA-AVHRR's detecting the same forest fire as "hot spots".
References
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Elvigde, C. D., et. al. (1997): Mapping City Light With Nighttime Data From the DMSP Operational Linescan System, Photogrammetric Engineering & Remote Sensing, 63, 727-734.
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Nakayama M. et. al. (1998): Contextual Algorithm Adapted for Fire Detection in Indonesia, International Journal of Remote Sensing, submitted.
