Quantification of Horizontal Forest Structure from High Resolution TanDEM-X Interferometric Coherences

Recent TanDEM-X experiments have shown that the limited penetration capability at X-band in forest volumes allow the estimation of the height variability of the top canopy layer, which can be used as a proxy to the horizontal structure (i.e. heterogeneity), by using high resolution digital elevation models (DEMs). However, the use of an external digital terrain model (DTM) is necessary to separate the (high resolution) canopy height variations from the topographic ones. In this work, the possibility of compensating terrain topographic variation by using a low resolution TanDEM-X DEM instead of an external DTM is investigated. The results show that the use of a reference DEM with a resolution on the order of 100 m allows to compensate the terrain induced topographic variations and to preserve the information on forest horizontal heterogeneity at a large extent