Evaluation of SMAP level 2 soil moisture algorithms using SMOS data

SMOS observations provide an opportunity to develop a testbed for the evaluation of different SMAP algorithm options. The use of real-world global observations will help in the development and selection of different land surface parameters and ancillary observations needed for the soil moisture algorithms. In this study, SMOS observations were used with one soil moisture retrieval algorithm and the results were evaluated using in situ soil moisture measurements. The SMOS soil moisture product, which exploits multiple incidence angle observations, compares well with the ground-based observations (RMSE 0.043 m³/m³ (ascending) and 0.047 m³/m³ (descending)). The alternative SMAP compatible algorithm also performed well (RMSE 0.040 m³/m³ (ascending) and 0.043 m³/m³ (descending)). Although preliminary, these initial results are encouraging for the potential of SMAP to meet its required soil moisture accuracy.