Radar Remote Sensing of Vegetation

Project: Digital Topography From SAR Interferometry: Determination of and Correction for Vegetation Height

Graduate Students: Yi-Cheng Li, Craig Wilsen, Charles Brown

Sponsor: NASA

The main thrust of this investigation is to characterize and quantify the role of vegetation attributes in determining the scattering phase centers as observed by a SAR interferometer. For this purpose analytical, numerical, and experimental aspects of electromagnetic scattering from a forest canopy are considered in this investigation. First a coherent electromagnetic scattering model based on a Monte Carlo simulation for three major classes of a forest canopy is under development. The Monte Carlo simulation, which includes multiple scattering between particles up second order, will be used to construct an empirical model for the height of the scattering phase center in terms of both radar parameters (wavelength, polarization and angle of incidence) and vegetation attributes (class, physical height, dielectric constant, etc.). The validity of the model will be verified using data collected by JPL's SAR interferometer (TOPSAR) over two well-characterized sites: the Raco Supersite used by SIR-C/X-SAR and the NSF Long Term Ecological Research Site at the Kellogg Biological Station near Kalamazoo, Michigan. The model and its inversion is intended to be used in conjunction with other ancillary information (such as digital elevation model or polarimetric SAR data) to develop and test four basic applications: (1) determination of vegetation height, (2) estimation of surface elevation for vegetation-covered regions, (3) determination of crown-layer properties from multifrequency SAR interferometry and (4) usefulness of SAR interferometric products in forest ecosystem mapping.