In case of fires, SAR images respond to changes in surface and vegetation. If the territory is engulfed in fire, the following appears on the images: Before it gets too hot: forests, fields and trees will look remarkably bright (the trees are very good at picking up the radar signal). Before and after burning: the burnt surface becomes smoother and is covered with a charcoal-black mass or ash. Such a surface may not transmit the radar signal back to the satellite, so the area on the SAR image appears dark.
In winter, SAR images of forests are mostly gray or dark, although they can appear lighter if the snow cover is uneven. During this period, trees have no leaves, so the signal reflection is lower. If there is snow on the branches, the signal is partially scattered, giving the image a light-gray tone. In spring, the images become brighter and more textured. This is due to the appearance of leaves and increased soil moisture, which enhances the scattering of radio waves. In summer, the forest appears medium-bright or bright and has a pronounced texture. Tree canopies are dense and contain a lot of moisture, so the forest strongly reflects the radar signal. The image often looks heterogeneous and “fluffy.” In autumn, the images gradually darken. Leaves fall, reducing signal reflection. However, after rains, bright areas may appear due to increased soil moisture.
Before: the forest appears heterogeneous and has a medium or bright
tone. This indicates dense tree canopies and high moisture content,
which strongly reflect the radar signal. In addition, dark areas are
visible, which are likely lakes or rivers, as water usually does not
reflect the signal back to the satellite. In the
After image, the
scene has become noticeably darker and less textured, especially in
the central area. This is the main change. Burned trees and fallen
leaves reduce the reflection of the radar signal, making the terrain
appear darker.
The surface appears mostly dark and uneven, with irregular dark patches indicating burned areas that reflect the radar signal weakly. Brighter spots suggest zones of moisture or partial vegetation recovery. The texture remains heterogeneous, showing clear traces of fire impact even two years later.
