Multitemporal Soil Moisture Retrieval from Three-Day Repeat ERS/SAR Data

The Sentinel-1 mission will offer the opportunity to obtain C-band radar data characterized by short revisit time, thus allowing the generation of frequent soil moisture maps through the application of multitemporal retrieval algorithms. Exploiting the availability of some archived ERS SAR data with a short revisit time, this paper compares the estimates obtained by applying a multitemporal algorithm, developed in a previous work, to moisture provided by a land surface model and in situ data, as well as to soil moisture products derived from low resolution satellite data (ASCAT and SMOS). Results indicate the multitemporal algorithm produces soil moisture estimates that agree with model and in situ data at watershed scale. At finer scale, SAR presents better performances than other satellite instruments when compared to in situ data, although the correlation is not very high.