On the soil moisture retrieval of bare soils with ERS SAR data

The value of the radar backscattering coefficient measured over bare soils at C-band has been shown to be sensitive to the presence of top soil moisture. However, several factors such as its fast dynamic variation and the soil surface roughness have made difficult the retrieval of this important hydrological parameter from SAR data. In order to improve this situation, accurate soil moisture measurements acquired every 10 minutes by "Theta" probes at two different depths (0-5 and 10 cm) spread out through the Flevoland agricultural test site in the Netherlands have been acquired by automatic stations as well as rain information. This site is also used for monitoring the calibration of the SAR instrument aboard the ERS-2 satellite which ensures that the area is often imaged. Using this high-quality in-situ data and the well-calibrated ERS SAR data, a preliminary analysis of the variation of the soil moisture is given.