Radar backscatter
The portion of a radar pulse that returns to the sensor, whose strength reveals surface structure such as canopy roughness or open water.
Synthetic aperture radar sends a microwave pulse toward the ground and measures what bounces back. The intensity of that return, called backscatter, depends on how rough and how wet the surface is, and on the geometry of what stands above it.
Backscatter behaves differently from optical reflectance. Smooth water scatters energy away from the sensor and appears dark; rough canopy returns a strong signal; flooded forest can brighten because trunks double-bounce the pulse. These signatures let analysts separate flooded from dry forest, and cleared from intact land, even through cloud.
In carbon monitoring, backscatter time series are used to detect abrupt loss of structure — logging, fire, conversion — within days, and to estimate biomass where radar structure models have been calibrated with field data.
Frequently asked questions
Does radar work at night?
Yes. Radar carries its own illumination, so it images day or night and is unaffected by cloud or haze.
Why can radar see through cloud when optical sensors cannot?
Microwave wavelengths pass through water droplets in clouds largely unattenuated, whereas visible and infrared light is blocked.