Characterization of the Temporal and Spatial Variability of Soil Moisture through Multi-Temporal Analysis of ASAR Observations

In this paper, synthetic aperture radar (SAR) based soil moisture retrieval results are presented using observations acquired over the Tibetan Plateau. Two different time series based methods are used for the retrieval of soil moisture. With method I, soil moisture is retrieved through scaling of the backscatter (sigma^o) observations between the maximum and minimum observed sigma^o at a specific location. For method II, soil moisture is retrieved using the integral equation method (IEM, Fung et al. 1992), for which a site-specific effective surface roughness parameterization is obtained through model inversion using minimum observed sigma^o. The retrievals are validated against ground measurements and showed that using method I and method II soil moisture can be estimated with accuracies up to 0.056 and 0.035 cm³ cm^-3 , respectively.