Synthetic aperture radar imaging of urban surfaces: a case study

A set of SAR images of the Los Angeles basin was analyzed to assess their potential to derive soil moisture, an important component of the surface energy balance in urban areas. Large variations of backscatter intensities were observed for different land uses and different SAR images. Low intensities were found over smooth pavement and asphalt. High intensities were found over industrial and commercial areas, with a marked illumination azimuth dependence for the latter; and maximum intensities were found when the flight direction was parallel to building alignments. A similar anisotropy occurred over residential areas, albeit at lower intensities. These contaminations mask the backscatter variations resulting from other processes, and may limit the estimation of soil moisture to undeveloped blocks and parks, unless a correction is applied