SOIL MOISTURE ESTIMATION USING ASAR DATA

摘要

The potential of Advanced Synthetic Aperture Radar (ASAR) for the retrieval of surface soil moisture over bare soils was evaluated for several ASAR acquisition configurations: (1) one incidence and one polarization, (2) one incidence and two polarizations (one date), (3) two incidences and one polarization (two dates) and (4) two incidences and two polarizations (two dates). The retrieval of soil moisture from backscattering measurements is discussed using empirical inversion approaches. When compared with the results obtained with a single polarization, the use of two polarizations does not provide a significant improvement in estimating soil moisture (improvement < 1%). For the best estimates of soil moisture, ASAR data should be acquired at both low and high incidence angles (RMSE=3.5%). Next, the soil moisture mapping was carried out for ASAR images acquired in 2005 over the Touch basin using empirical relationship between radar signal and soil moisture obtained from data collected between 1998 and 2004 on several study sites and in using ERS and ASAR sensors. The use of mono-date ASAR images with one incidence and one polarization enables a soil moisture mapping with accuracy better than 6%.