Global Forest Monitoring with Synthetic Aperture Radar (SAR) Data

Remote sensing data acquired by synthetic aperture radar (SAR) provide unique opportunities for forest characterization, mapping, and monitoring, largely because of sensitivity of the radar signal to vegetation physiognomic structure and the provision of observations that are largely independent of atmospheric (e.g., cloud and smoke haze) and solar illumination conditions. Spaceborne SAR have been operating at a near global level since the 1990s, and the wide range of frequencies, polarizations, and observation strategies provide numerous opportunities for retrieving information on the past and current state of forests and surrounding landscapes and changes associated with natural and anthropogenic change, including climatic fluctuation. The development of systems and algorithms for characterizing, mapping, and monitoring forests, however, has been informed by studies using data acquired by SAR onboard airborne and spaceborne systems (e.g., the Shuttle Imaging Radar) and through dedicated missions.