Enhancement of Nighttime Fire Detection and Combustion Efficiency Characterization Using Suomi-NPP and NOAA-20 VIIRS Instruments

We present the second-generation FIre Light Detection Algorithm (FILDA-2), which includes advances in fire detection and retrievals of radiative power (FRP), fire visible energy fraction (VEF), and fire modified combustion efficiency (MCE) at nighttime from the holistic use of multiple-spectral radiances measured by the visible infrared imaging radiometer suite (VIIRS) aboard Suomi-NPP (VNP) and National Oceanic and Atmospheric Administration (NOAA)-20/joint polar satellite system (JPSS)-1 (VJ1) satellites. Key enhancements include: 1) a new fast algorithm that maps VIIRS day/night band (DNB) radiances to the pixel footprints of VIIRS moderate (M) and imagery (I) bands; 2) identification of potential fire pixels through the use of the DNB anomalies and I-band thermal anomalies; 3) dynamic thresholds for contextual testing of fire pixels; and 4) pixel-specific estimates of FRP, VEF, and MCE. The global benchmark test demonstrates that FILDA-2 can detect approximately 25%-30% smaller and cooler fires than the operational VIIRS active fire 375-m I-band algorithm with the added benefit of providing daily global pixel-level characterizations of MCE for nighttime surface fires. The MCE derived by FILDA-2 is in good agreement with limited ground-based observations near the fires. Additionally, FILDA-2 reduces angular dependence in FRP estimates and significantly reduces the "bow-tie" (double-counting) effect in fire detection compared with the AF-I product. The cross-validation of FILDA-2 products from VNP and VJ1 retrievals confirms good consistency in FRP and MCE retrievals globally. FILDA-2 is being implemented by the National Aeronautics and Space Administration (NASA) to generate a new VIIRS data product for fire monitoring, chemical-speciated fire emission estimates, and fire line characterization.