The Effects of Sloping Terrain for Inversion of Pinus Yunnanensis with Spaceborne SAR Data

Abstract

SAR (Synthetic Aperture Radar, SAR)with its particular imaging mechanism and the capability of acquiring data in any time became a new tool to estimate forest biophysical parameters and forest biomass. However, the effects of terrain slope must be addressed towards the generalization of biomass retrieval for varied forest and environmental conditions. Terrain undulations affect the geometric and radiometric quality of SAR images. For the correction of geometric effect there are some precise model such as RD position model with simulated SAR images and DEM. With the analysis we found that there are two facets influence the radiometric effects: (i) the illuminated target area, (ii) changing scattering mechanisms due to different incident angles. In this paper, we developed experimental approaches to study the sensitivity of ENVISAT ASAR C-band HV data to the biomass of Pinus yunnanensis. With the analysis of radiometric correction such as uncorrected backscatter, the terrain corrected with illuminated target area and the angular corrected backscatter, we found that the correlation between Pinus yunnanensis biomass and the backscattering coefficient became increasing with the corrected of each levels of terrain effects.