A new approach for the validation of coarse-resolution satellite soil moisture products

Soil moisture plays a crucial role in the terrestrial water cycle. It can be estimated by manual measurements for a small watershed, while this is very time-consuming when applied in the large scale. The remote sensing technology provides a new approach to monitor the soil moisture in a large scale. However, it should be evaluated before being used. In the study, the L-band Microwave Emission of the Biosphere model (L-MEB) model was used to retrieve the soil moisture based on the airborne brightness temperature in the Heihe River Basin, then the retrieved soil moisture was aggregated to 25km based on the area weighting factor method. The aggregated soil moisture was used to validate the two AMSR2 data: the JAXA soil moisture products and the LPRM soil moisture products. The results shows the JAXA SM products has an underestimation compared with the pixel-averaged SM, and the LPRM SM products is higher than the pixel-averaged SM.