Estimating the ground heightwith L-band IfSAR in a wind-blown forest environment

The horizontal and vertical (3D) structure of Earth´s forested ecosystems are of great significance to their ecological functioning and societal uses. An IfSAR approach is one methodology whereby a forest´s structure and height in particular can be successfully estimated. Critical to the successful estimation is a high correlation between multiple SAR images. Regardless of a forest´s location on the Earth, motion due to wind can significantly alter a forest´s appearance to a radar system operating at L-band and so too decrease this necessary correlation. In order to investigate and quantize the decorrelation induced by the wind, we have developed a model that is capable of generating both a single-pass and repeat-pass interferometric SAR response of a forest including the application of a randomly oriented wind field. The simulation consists of multiple interconnected parts including the generation of fractal tree geometries, a wind simulator to apply variable wind forces to the generated trees, an electromagnetic model to allow us to calculate a fully polarimetric Single Look Complex value for the SAR return of the combined target, and an IfSAR processing algorithm capable of calculating a scattering phase center in the presence of wind. Results present polarimetric scattering phase centers and interferogram coherence as a function of wind speed. We further deconstruct our SAR processor to yield individual scatting mechanisms and their resultant scattering phase centers. This deconstruction allows for an accurate estimate of the underlying ground to be generated, even in the presence of a strong wind field.