Validation of satellite soil moisture products in china using ground-based observations

Remote sensing soil moisture (SM) products are an important source for obtaining surface soil moisture and have been widely used in large-scale hydrological, land surface, and ecological studies. The accuracy of remote sensing products determines the reliability of these applications. In this study, we evaluated three long time-series SM remote sensing products CCI, NNsm, and FY3B in China using SM measured at 732 stations. It is found that all three products tend to underestimate the surface SM. CCI has the highest correlation coefficient with ground observation, implying CCI may have an advantage in predicting long periods of drought. The differences in bias are related to the type of land cover. However, newly developed SM products need to be further validated to provide a solid reference for data selection in China.