Synthetic Aperture Radar for Land Applications

Synthetic aperture radar (SAR) is an active sensor that operates in the microwave region of the electromagnetic spectrum, offering the significant application advantage, with respect to optical sensors, of providing all-weather and all-time imaging capabilities. SAR backscattering is related to the dielectric and geometric properties of the imaged surface and can be used to derive remotely several useful parameters. Spaceborne SAR sensors provide global and periodic coverage of the Earth on a regular and long-term basis, being valuable for environmental monitoring at a global scale. The article introduces the principles of SAR imaging, the main acquisition modes, and the current spaceborne SAR missions. Then it reviews some land parameters that can be derived from spaceborne SAR sensors, which are relevant for studying the global water and energy cycle and hence can be used in input to climate and atmospheric models.