Wildfires periodically devastate North American landscapes. In a new time-lapse video, the scorched earth and incremental recovery of Yellowstone National Park are visible via NASA satellite imagery.
Tall, healthy forests and their subsequent destruction during the 1988 fire season appear in a series of false-color images taken by satellites over the course of 30 years. According to the description on the newly released pair of videos, U.S. Geological Survey-NASA Landsat satellites observed tall, healthy forests (visible as dark green regions in the video) transform into burned-down areas (shown in a dark reddish-brown color), before slowly recovering.
The scars slowly fade and new vegetation takes root over time, according to the video description. The renewal process begins with grasses, continues with shrubs and then moves on to progressively taller trees. [See Smoke from 110 Fires Spread Across the US in This Satellite View]
The time-lapse video demonstrates how long it takes for a forest to fully recover to its state before the fire. Imagery taken by satellites some 20 years after the wildfire reveals that the forests are still not back to their original lush state.
In the second video, Landsat Project Scientist Jeff Masek talks about how the satellites acquire their insightful imagery.
"Landsat actually images the Earth using a variety of spectral bands in different wavelengths. Some of these wavelengths are not visible to the human eye but are useful for assessing the composition of the land surface," Masek shared in the video. "The red wavelength, for example, is sensitive to leaf area, because the chlorophyll in leaves tends to reflect a lot of light in the near-infrared … we've assigned the short-wave infrared band to the red. We've assigned the near-infrared band to the green, and we've assigned the green band to the blue.
"And that creates what we call a 'false-color' image," Masek added. "It's not exactly what you're eye would see, but it's quite convenient, because the healthy vegetation shows up as green and so we can, sort of, automatically interpret that."
The U.S. is witnessing record-setting wildfires this year, and satellite imagery continues to play a role in the documenting and monitoring of the regions across the world where wildfires are currently active.