Tropical-Forest Density Profiles from Multibaseline Interferometric SAR

Vertical profiles of forest density potentially are robust indicators of forest biomass, fire susceptibility and ecosystem function. Tropical forests, which are among the most dense and complicated targets for remote sensing, contain about 45% of the world's biomass. Remote sensing of tropical forest structure is therefore an important component to global biomass and carbon monitoring. As in radio astronomy, which uses multibaseline radio interferometry to measure the structure of celestial objects, so multibaseline interferometric SAR (InSAR) can be used to estimate the vertical structure of forests. Vegetation density profiles, along with radar backscattering characteristics and attenuation, determine the radar brightness profile "seen" by InSAR. This paper will describe an experiment at La Selva Biological Station in Costa Rica (~3m rainfall/year) in which we flew 18 effective fixed baselines over tropical forests at C-band (0.056 m wavelength) and L-band (0.25 m). Preliminary inversions for radar brightness profiles will be compared to extensive lidar profiles measured in the same area. They will also be compared to field-measured profiles.