Estimating Canopy Height of a Temperate Forest from TanDEM-X and LVIS Data

Abstract:

The recently launched TanDEM-X mission is the first single-pass polarimetric interferometer in space allowing global estimation of forest parameters without any temporal decorrelation. This study investigates the potential of single-polarized TanDEM-X data for forest height inversion and structure characterization. For this purpose, a temperate forest - Hubbard Brook Experimental Forest (HBEF) in New Hampshire is chosen for experiment. Stripmap-mode HH-polarized TanDEM-X bistatic data (with resolution at 3 m) acquired at different baselines was used. LVIS data was applied to remove the ground phase component of the TanDEM-X interferogram and to validate the derived results. Forest parameters, e.g. canopy height and extinction coefficient were estimated based on Random Volume over Ground (RVoG) model. Scattering phase height (SPH) was also calculated and validated against LVIS rh100. A clear correlation was observed between TanDEM-X SPH and the reference height with an r² of around 0.6 at 150m resolution. The inverted tree height had an RMSE of less than 3.4 m and an r² of around 0.7 at the same resolution. It is shown that TanDEM-X data has great potential for improving the understanding and quantification of global forest canopy height and structure.