Speaker
Description
The history of satellite observations of fires and flares in the infrared from space extends back to the 1970's. Most of the products relied on detection with a midwave infrared spectral band near 4 um and a longwave infrared band in the 10-12 um range. These data products are referred to as "hotspots" as it is impossible to calculate temperature or source area for subpixel heat sources from a single spectral band. In 2012, a new style of multispectral infrared emitter data product was developed based on nighttime infrared data from the NASA/NOAA Visible Infrared Imaging Radiometer Suite (VIIRS). This data product, known as VIIRS Nightfire (VNF), detects infrared emitters such as wildfires, natural gas flares, and steel mills. VNF relies on near-infrared and shortwave-infrared radiances from spectral bands designed for daytime imaging of reflected sunlight. At night, these spectral bands record the sensor's noise floor and clusters of high radiance pixels associated with infrared emitters at the Earth's surface. Temperature, source area, and radiant heat are calculated for each VNF-detected pixel using physical laws, including Planck's Law, Wien's Displacement Law, and the Stefan-Boltzmann Law. Multiple years of VNF data are composited to identify fixed location infrared emitters. The emitter sites are labeled for type and nightly temporal profiles are generated back to 2012. The temporal profiles are updated once per week. The data are currently used in estimating flared gas volumes. Temporal profiles are available from a webmap service known as the Global Infrared Emitter Exlorer (GIREE). We currenly track more than 20,000 emitters worldwide. VNF is the largest global infrared monitoring system gas flaring and industrial waste heat.
