Fire Watch: Watching and Understanding Wildfires from Space
By early summer the North American fire season is usually in full swing, and so far 2016 is no exception. According to the National Interagency Fire Center there had been 24,676 wildfires in the U.S. as of June 28, burning a total of 2,069,214 acres.
Southern and Central California have been particularly hard hit, with major fires near Santa Barbara, Los Angeles, Bakersfield, and Carmel.
The map above shows fires (including gas flares) detected June 21–June 28, 2016 by the Visible and Near Infrared Sensor (VIIRS) on the NASA/NOAA Suomi-NPP satellite.
Don’t be alarmed—the East is not suffering an epidemic of wildfires. Fire detections east of the Mississippi appear as loose clusters or red dots and likely represent small agricultural fires, while dense clusters of red pixels in the West are large wildfires. In North Dakota and Texas VIIRS detected large numbers of gas flares in the newly-tapped oil fields.
Satellite imagery has long played an important role in fighting wildfires, from estimating the amount of dry vegetation available to fuel a fire to evaluating the severity of a burn in the wake of a blaze. The rapid revisit rates and relatively high resolution of Planet’s RapidEye and Dove instruments allow unique ways of preparing for, monitoring, and responding to fires.
These images show the site of the San Gabriel Complex fires, which ravaged the mountains north of Los Angeles. Starting on June 20, 2016, the Reservoir Fire and Fish Fire consumed a total of 9652 acres, before being contained about a week later.
On the left is a true-color image, showing the area On June 4, 2016, more or less as it would appear to a human observer. The dark green, chaparral-covered hillsides contrast with gray rooftops and roadways — the northern fringes of the Los Angeles conurbation.
On the right-hand side is a map of Normalized Difference Vegetation Index (NDVI), a measure of plant health and abundance. Dark green represents thick, vigorous plant cover, while lighter greens represent thinner and less healthy vegetation. Beige areas are vegetation free — bare soil, rock, asphalt, or concrete.
Vegetation Index maps are a valuable fire-fighting tool because they show fuel available to feed a fire. This can help land managers plan efforts to thin vegetation on vulnerable land to limit the intensity of damaging fires, or prevent them from spreading in the first place.
True-color and near-infrared false-color views of the San Gabriel Complex fires show the extent of the blazes on June 22. In true-color (left), smoke is blue-brown, burned areas are dark gray, and flame retardant foam laid down in front of advancing flames is bright red. In false-color (right), the smoke almost disappears, leaving a clear view of the burn scar. More severely burned areas are darker. Vegetation appears bright red, and water is dark blue.
Satellite images are also beneficial during a fire. Up-to-date vegetation data can help predict the propagation of a fire, especially when combined with additional information like topographic maps, weather data, and land cover classification. This allows firefighters to efficiently combat wildfires and protect at-risk property.
Additionally, satellite data is used to help respond in the aftermath of a fire. The USDA Forest service employs Burned Area Emergency Response teams to evaluate the severity of fires, and quickly rehabilitate areas vulnerable to threats like erosion and the spread of invasive species.
During a wildfire, when critical decisions need to be made quickly, Planet’s rapid imaging cadence and moderately high resolution data can fulfill the need for real-time information and pinpoint accuracy.