Geostationary Active Fire Detection Data in FIRMS

Users of NASA's Fire Information for Resource Management System (FIRMS) routinely leverage active fire detection data derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Visible Infrared Imaging Radiometer Suite (VIIRS). These sensors are aboard polar-orbiting satellites and provide a "snapshot" of fire activity at the time of satellite overpass for a given geographic area. Polar-orbiting observations by each individual MODIS and VIIRS sensor are conducted once to twice daily in the equatorial region of the globe and as many as eight times daily in the very high latitudes. What if you want multiple observations and updates on detected fire activity every hour? Geostationary satellite instruments can meet that need.

Unlike polar-orbiting satellite instruments, geostationary satellite instruments stay at a fixed point above the equator and follow Earth's daily rotation on its axis. Their orbits are 45 to 50 times higher than MODIS, VIIRS, Landsat, and other polar-orbiting instruments that operate in an orbit about 700 to 800 km above Earth's surface. These characteristics allow geostationary satellite sensors to move with Earth's rotation and persistently observe a very large portion of Earth's surface centered on their location.

Several geostationary platforms and instruments are designed to support meteorological observations and have spectral bands that span the visible, near infrared, and thermal infrared. These capabilities also enable them to support the detection and monitoring of fire activity. Additionally, geostationary instruments provide outstanding temporal resolution acquiring imagery for their entire field of view at 10 to 15 minute intervals or better. This enables geostationary instruments to potentially detect more fire events and capture their growth and change, particularly between fire detection observations conducted by sensors on polar-orbiting platforms. However, geostationary instruments have a much coarser spatial resolution than polar-orbiting instruments and can be less sensitive to detecting relatively smaller fires.

Active fire detection data from five geostationary instruments are available in FIRMS and collectively provide global coverage. Two geostationary satellites—GOES-16 and GOES-18—are operated by NOAA and provide coverage for the Western Hemisphere. The other three satellites—Himawari-8, Meteosat 9, and Meteosat 11—are operated by JAXA (Japan Aerospace Exploration Agency) and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and provide coverage for the Eastern Hemisphere and a substantial portion of the Western Hemisphere. Overlapping coverage is also provided by adjacent instrument fields of view. General information about the geostationary satellites used in FIRMS and their associated instruments, fire detection algorithms, and derivative product information are summarized below.

Here are two important considerations when using active fire detection data from geostationary satellites: 1) The coarse spatial resolution of geostationary satellites should be taken into consideration; the spatial resolution sub-nadir (i.e. directly below the satellite) is between 2 km to 3 km for the different geostationary satellites (compared to 1 km, 375 m, and 30 m for MODIS, VIIRS, and Landsat, respectively). An active fire could be located anywhere within that 2 km to 3 km pixel; 2) Distortion in the pixel size of geostationary satellites increases towards the poles. This change in pixel size for the GOES-16 geostationary satellite is shown in the figure below. (To view the pixel sizes for the other geostationary satellites visit the FIRMS FAQ What is the spatial resolution of the geostationary satellite observations?)

Due to technical and environmental factors, active fire detection outputs from the current generation of geostationary algorithms can be prone to significant errors of commission and/or omission. Consequently, FIRMS considers all geostationary data as provisional or beta, and filters detections to display only those at the higher levels of detection confidence for each product. The filtered geostationary active fire detection data layers from each instrument/algorithm are available under the GEOSTATIONARY section of the Fire / Hotspots group in the FIRMS legend. They are accessible with the Advanced Mode selected. Each geostationary active fire detection layer is named by the source satellite and providing agency (see each layer’s information summary for more details). Additionally, for user convenience, the outputs for GOES FDC-HSC, Meteosat FRP-PIXEL, and Himawari FRP-PIXEL algorithms are grouped into a single layer called Filtered Geostationary (provisional).

GOES ABI and Himawari AHI active fire detection data at 2 km resolution are observed every 10 minutes throughout a 24-hour period while Meteosat SEVIRI active fire detection data at 3 km resolution are observed every 15 minutes. This global harmonized, multi-sensor data stream is enabled by an automated framework developed by the University of Maryland under the auspices of the NASA Earth Action (formerly Applied Sciences) Program. All the sources of geostationary active fire detection data are available in FIRMS approximately 30 minutes or less post-observation. Users are advised to note that two active fire detection data products from GOES ABI imagery and derived from separate algorithms are provided in FIRMS.

The current versions of geostationary active fire detection algorithms are undergoing additional development, refinement, and tuning. FIRMS will provide outputs based on new or updated algorithms when they are introduced into operational production by the source agencies. Stay tuned for additional FIRMS blog entries with more information on the algorithms, products, and characteristics for geostationary active fire detection data and caveats users should consider when utilizing these data in FIRMS.