BIRD fire recognition and comparison with Terra/MODIS

Abstract

Data of the MODerate resolution Imaging Spectro-radiometers (MODIS) on the Terra and Aqua satellites are widely used for global and regional monitoring of active fires. MODIS, with their infrared channel resolution of 1 km at nadir do omit small fires, which leads to an underestimation of the cumulative fire radiative power (FRP) on a regional or global scale. In order to estimate the significance of this effect, we compared the number and characteristics of fires detected by Terra/MODIS with those detected by the DLR small satellite BIRD. BIRD is dedicated for fire recognition, providing a resolution of 370 m at nadir in its infrared channels and allows the detection of smaller fires than MODIS by a factor of 7. For the comparison we used data acquired near-simultaneously by Terra/MODIS and BIRD over fires in Siberia, Australia and Portugal. The results show that (1) the FRP of more than a half of the hot clusters, which were detected by BIRD, is below the detection limit of MODIS, (2) MODIS does only slightly underestimate the cumulative FRP in ecosystems where large fires take place and therefore (3) MODIS is hardly suitable for an early fire detection, but it is an adequate instrument for cumulative FRP estimation.