Validation of SMOS and Aquarius soil moisture using two in situ networks in Spain

A comprehensive spatial and temporal validation of long-term dataset of SMOS (Soil Moisture and Ocean Salinity) and Aquarius-derived soil moisture estimates was made using two in situ networks (REMEDHUS and Inforiego) within the Duero River Basin (Spain). Results from comparison with in situ show that the SMOS L2 product has better accuracy (with values of R>0.8 and cRMSD<;0.04 m³m^-3) than Aquarius L3 product (with R<;0.5 and cRMSD<;0.111 m³m^-3). Validation based on comparisons between dense/sparse networks showed that temporal patterns of soil moisture are well reproduced, whereas spatial patterns are difficult to depict given the different spatial representativeness of ground and satellite observations.