Forest Canopy Height Mapping from Dual-wavelength Sar Interferometry

The CORSAR project (Carbon Observation and Retrieval from SAR), which is supported by the UK Natural Environment Research Council (NERC), has the objective to examine polarimetric decomposition and polarimetric SAR interferometry methods for estimating the effects of canopy structure in biomass-backscatter relationships. Forest canopy height is a useful input parameter to yield models, carbon cycle models, and habitat maps for biodiversity conservation. SAR interferometry can used to produce digital elevation models from the interferometric phase. The penetration of the radiation into the canopy and thus the height of the effective phase scattering centre depends on wavelength and polarisation. Multi-wavelength SAR interferometry shows differences of the vertical locations of the effective phase scattering centres. We present a canopy height model derived from airborne X-band VV polarised single-pass SAR interferometry and Lband HH polarised repeat-pass SAR interferometry. The E-SAR data were acquired during the SAR and Hyperspectral Airborne Campaign (SHAC 2000). The accuracy of the SAR derived canopy height model is assessed. The model is compared to a LIDAR derived canopy height model that was acquired at the time of the campaign. The LIDAR model is more accurate and has a higher spatial resolution. However, the significance of a dual-wavelength canopy height product from SAR alone is that it can potentially be delivered from space.