Speakers: Chris Elvidge, Colorado School of Mines

Abstract: Biomass burning is a coupled system of exothermic and endothermic phases.  The exothermic phase includes flaming and smoldering, consumes oxygen, and produces the heat that drives endothermic processes.  The endothermic phase is non-flaming and includes pyrolysis and preheating.  Pyrolysis primarily involves the vaporization of lignin and cellulose, producing volatile gases consumed by the flaming phase.  The flaming phase temperature is about 1000 K, and pyrolysis occurs at 500-600 K.  The Planck curves of the flaming and non-flaming phases overlap in the midwave-infrared, near 4 μm.  The Planck curves are offset spectrally, as described by Wien's Displacement Law.  EOG has developed a "flaming-subtractive" method for unmixing the radiant emissions of flaming and non-flaming combustion phases with nighttime data collected by VIIRS instruments.  Flaming-phase radiant emissions are sampled in the near-infrared and shortwave-infrared regions for modeling of the flaming-phase Planck curve.  The flaming phase radiances are subtracted from all the VIIRS radiances, and the residuals are analyzed for an ambient temperature background and the non-flaming phase.  This analysis requires an atmospheric correction to account for wavelength-specific differences in atmospheric transmissivity.

Speaker Bio: Chris Elvidge received a Ph.D. In Applied Earth Sciences from Stanford University in 1985.  He led the development of three global low-light imaging data products: nighttime lights, VIIRS nightfire, and VIIRS boat detections.  His work on global monitoring of fires and natural gas flaring from space dates back to 1995, based on low-light imagery collected by the U.S. Air Force Defense Meteorological Satellite Program (DMSP).  In 2012, he developed the concept for the VIIRS Nightfire algorithm (VNF). Today, VNF data are widely used for cataloging and analyzing natural gas flares and other industrial heat sources worldwide. His publications have been cited over 40,000 times.