The King Fire blazed across headlines earlier this month when it morphed from a minor incident near the hamlet of Pollock Pines, California, into a massive wildfire that has since scorched more than 140 square miles of parched, rugged terrain.
Seven thousand firefighters have been called in to battle the flames, according to the Los Angeles Times, but the fire has resisted efforts to contain it. It continues to march toward Lake Tahoe, where its smoke suffocated last week’s Ironman Triathlon and impressive displays of pyrocumulus clouds billowed on the horizon.
After battling the blaze for two weeks, fire managers say they are settling in for a longer fight, but how do they go about developing a strategy? For enormous wildfires like this, how do they even determine what’s burning and where to attack?
It would be impractical for firefighters to map the entire fire from the ground, especially in challenging territory like the Sierra Nevada foothills. And the cameras mounted on buildings and lookout stations only keep an eye on a few fixed points along the sinuous and shape-shifting perimeter of a blaze.
Instead, fire managers have started looking to an unexpected place: the sky. Over the past few decades, scientists have developed instruments that collect information about the Earth’s surface from planes and satellites. These techniques are known as remote sensing methods, and the data they produce have proven vital to managers fighting behemoths like the King Fire, said Russ Johnson, director of public safety and homeland security at the geographic information systems company, Esri.
“It’s greatest value is not so much in detecting wildfires,” he said. “It’s more about when you have large wildfires and they are spreading rapidly, and you are planning the next day’s operational period.” As a former fire manager with the US Forest Service, Johnson knows the kinds of questions that run through the minds of fire crews: “Where am I going to put my dozer lines? What are we going to do to get in front of this thing and stop it?” he says.
Planes and satellites can help planners zoom out and see the big picture of the threat posed by the fire. For example, NASA’s Moderate Resolution Imaging Spectroradiometer, or MODIS, rides on the orbiting satellites Aqua and Terra, and measures the visible and infrared light emitted by Earth.
Visible light produces pictures like the one above, captured by Aqua while sailing high above the King Fire last week. Infrared radiation is particularly helpful because it tracks the temperature of Earth’s surface (think of the infrared goggles used in spy movies that let the wearer “see” heat). This capacity allows scientists to identify suspicious hotspots.
Computers on the ground then analyze the satellite data, searching for indications of fire and smoke, eliminating false alarms like heated pavement, and providing updates on fire conditions within hours of flying over a burn.
Unfortunately, neither of these satellites can distinguish features smaller than a half mile or so in diameter, so to dive into the details, scientists and land managers also use the precise images collected by the US Geological Survey’s Landsat satellites. High-resolution instruments on board these vehicles can make out objects smaller than 100 feet. Since pictures are only collected once a week, they are most useful for evaluating the damage to charred areas after a fire.
But the best information, Johnson said, comes from infrared sensors on planes that fly over fires while they burn. These work just like the sensors on satellites, but provide much more detailed heat maps and produce almost immediate results.
“In the right set of circumstances, you can have almost real time heat sensing and infrared from aircraft,” Johnson said. Managers then get satellite imagery a few hours later and combine the this information with observations made by crews on the ground to keep tabs on how the fire’s evolution.
But managers have only recently had these tools at their disposal. Just 15 years ago, neither the sensors to collect data on fires or the computing capabilities to analyze it existed. And few were originally designed with fire management in mind — they were built for scientific purposes, like tracking weather conditions and monitoring ongoing climate and land use changes around the world.
Since their invention, however, remote sensing has changed how firefighters tackle mammoth blazes. And they promise to keep improving too; researchers at UC Berkeley have developed new technology to detect fires as small as 10 feet across in the hopes that satellites might catch them before humans do. They know that a bird’s eye view may be the best vantage point of all.
Find out how different satellites help scientists monitor fires from space at NASA’s Earth Observatory.
Monitor current fires using Esri’s Wildfire Activity Public Information Map, which uses information from satellites.
Written by Julia Rosen
Julia Rosen is a freelance science writer and PhD student at Oregon State University. She received a Bachelors degree in Geological and Environmental Sciences from Stanford University before beginning her doctoral research on polar ice cores and climate change. In between, she did her Master's in backpacking around the world and skiing. Julia is a periodic contributor to Oregon States research magazine, Terra, and helps write blog content and develop learning modules for Visionlearning.