Application of algorithms for estimating surface soil moisture and roughness parameters using CRL/NASDA airborne SAR (PI-SAR) data

The goal of this study is to develop an algorithm for estimating the surface soil moisture and surface roughness using polarimetric synthetic aperture radar (SAR) data. In this study, an algorithm was applied to polarimetric airborne SAR data to estimate distributions of surface soil moisture and roughness. To validate the estimated soil moisture, the authors simultaneously conducted an experiment in October 1999 in Tsukuba, Ibaragi Pref., Japan. Surface soil moisture was obtained by the time-domain reflectometry (TDR) method, and the horizontal profiles of the land surface height were measured by a comb-style instrument for calculating the surface roughness parameters in test sites. Because the problem is site-specific and depends upon the measurement accuracy of both the ground truth data, and the SAR system including speckle noise, the comparison results did not agree well with measured and inferred soil moisture