Exploring vegetation profiles from TanDEM-X phase, lidar, and field measurements in tropical forests

Abstract

This paper explores the hypothesis that few-look phases from TanDEM-X have information about the vegetation profile over 50 × 50 m stands in tropical moist forests in Brazil. The formalism for modeling the interferometric phase of interferometric SAR (InSAR) is examined before taking the look, or ensemble average. It is suggested that it is the look averaging that produces the Fourier transform of the radar power profile in InSAR. Before the look averaging, a histogram of InSAR phases seems related to the radar power profile, which, in turn, is related to vegetation density. After a qualitative argument about the information in the few-look phases, 2-look phase histograms are shown along with lidar waveform profiles and modeled field profiles. It is observed that, for taller stands, TanDEM-X profiles are narrower than lidar and field profiles, suggesting less penetration. There is some suggestion that lidar ground finding needs honing and/or there has been disturbance over the observation period between 2010 and 2012. © VDE VERLAG GMBH · Berlin · Offenbach, Germany.