Category: Radar (SAR)
Backscatter
Backscatter is the amount of radar signal returned to the sensor, influenced by roughness, moisture, and structure.
Also known as: sigma0, sigma nought, dB backscatter
Expanded definition
Backscatter is a measure of how strongly a surface reflects radar energy back toward the sensor. Smooth water typically has low backscatter, while rough surfaces and certain vegetation structures can have higher backscatter.
Backscatter changes with soil moisture, crop growth, and tillage, which makes SAR useful for monitoring when optical data is unavailable. At the same time, backscatter is sensitive to geometry and acquisition settings, so comparisons must be made carefully.
Backscatter is often provided in linear or logarithmic scale (dB). Understanding the scaling is important when building thresholds or time-series models.
Related terms
SAR (Synthetic Aperture Radar)
SAR is an active radar sensor that works day or night and can see through clouds, measuring surface scattering rather than reflected sunlight.
Incidence Angle
Incidence angle is the angle between the radar beam and the surface; it affects SAR backscatter and comparability.
Polarization (VV, VH, HH, HV)
Polarization describes the transmit and receive orientation of radar waves; different polarizations respond to different surface properties.
Time Series
A time series is a sequence of observations over time for the same location, used for monitoring and change detection.