Evolution of a Wildfire

December 02, 2019
The Decker Fire burning in the mountains near Salida, Colorado, on October 3, 2019, courtesy of BFS MAN via Flickr.

The Decker Fire burning in the mountains near Salida, Colorado, on October 3, 2019.

BFS MAN / flickr / CC BY-NC 2.0

Wildfires that strike heavily-populated areas often get significant media coverage along with the increases in budgets and resources needed to contain them. But what can be done to monitor and fight wildfires raging in the more remote parts of the world?

On September 8, 2019, a lightning strike sparked a fire that smoldered on the southern slopes of Colorado’s Sangre de Cristo Mountains near the city of Salida. Firefighters worked to steer the slowly-spreading fire, dubbed the Decker Fire due to its proximity to Decker Creek, away from the few homes and structures in the area. It did not pose a substantial threat to the general public, so land managers let it remain largely uncontained to allow it to clear out dead and dry vegetation.

However, on October 1, low humidity and wind gusts created fire conditions that pushed the blaze to the north side of the ridge, closer to Salida. This direct threat to the city mobilized authorities to aggressively combat the fire with fire breaks and aerial water drops that controlled the direction and intensity of the fire. At its greatest extent, the Decker Fire burned over 36 square kilometers (9,000 acres) of the Rio Grande and San Isabel National Forests. Six weeks of concentrated efforts were able to get the fire 75 percent contained, with an estimated full containment date of December 20. However, the solution to natural disasters can sometimes be found within nature itself. A heavy snowfall on October 23 doused the last remnants of the Decker Fire.

First responders and civic officials can utilize thermal anomalies and fire products from lower-resolution remote sensing instruments, such as the Suomi National Polar-orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS), to monitor how a fire is evolving. For large events such as the Decker Fire, the accuracy of the daily S-NPP NASA VIIRS Thermal Anomalies/Fire (VNP14A1) 1-km product can be shown in the time series below. This time series follows the various flare-ups detected by S-NPP NASA VIIRS, indicated by the red pixels. Deeper red colors specify areas under a longer and more pronounced burn. The underlying image was acquired from the higher-resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Precision Terrain Corrected (AST_L1T) product on October 12. Burn scars in the ASTER image can clearly be seen in the corresponding regions of the VIIRS data, and several fires and smoke plumes are identifiable on the eastern edge of the ridge.

For information on how to apply to be an approved user and submit a request for on-demand ASTER data, visit the NASA JPL ASTER website on Requesting New Acquisitions. All users with a NASA Earthdata Login Account can access archived ASTER data through NASA Earthdata Search.

Material written by Bradford Wirt​1

1 KBR, Inc., contractor to the U.S. Geological Survey, Earth Resources Observation and Science (EROS) Center, Sioux Falls, South Dakota, USA. Work performed under USGS contract G15PC00012 for LP DAAC2.

2 LP DAAC work performed under NASA contract NNG14HH33I.


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