Modified scattering decomposition for soil moisture estimation from polarimetric X-band data

Abstract

Soil moisture content represents a key observable in order to model, describe and predict many ecological processes. In the last decades, theoretical and empirical inversion algorithms for soil moisture estimation using PolSAR data at L- and P-band have been intensively investigated, and, meanwhile, there exist some innovative techniques for the quantitative retrieval of dielectric constant of the soil. In this project work, the potential of estimating soil moisture from fully polarimetric X-band SAR data is investigated for the first time. The acquisitions were made by the German satellite TerraSAR-X over the agricultural area of Wallerfing (Lower Bavaria) in April/May 2009. Due to the short wavelength, the Physical Optics model has been chosen for representation of the scattering process and a model-based three component decomposition approach has been followed to exploit the polarimetric observable space. In order to improve the retrieval of the moisture content, the developed polarimetric decomposition has been further modified by means of an eigen-analysis of the coherency matrix and corrections of the volume scattering contribution were done. A validation of the proposed approaches for a quality assessment has been performed by comparing the estimated moisture values with in situ measurements collected in collaboration with the Ludwig-Maximilians-Universität (LMU) München.