An intercomparison of the spatial-temporal characteristics of SMOS and AMSR-E soil moisture products over Mongolia plateau

In this study, we inter-compared the spatial-temporal characteristics of SMOS and AMSR-E soil moisture products over Mongolia plateau. The results show that in temporal scale, the standard deviation of SMOS soil moisture data is higher than JAXA and ECMWF products, comparable to the in situ observation. To demonstrate the spatial variation of SMOS and JAXA soil moisture products, we first defined the smoothness index (SSI). The mean and maximum value of SSI of SMOS are much higher than those of JAXA and ECMWF for both daily and monthly soil moisture products. The mean value of SSI of daily SMOS products is 1.284, while that of JAXA and ECMWF is 0.010 and 5.010@10^-4, respectively. For monthly products, the mean value of SSI of SMOS is 0.264, while the value of JAXA is 0.004, and 3.753*10^-4 for ECMWF. Further, we counted the SSI of SMOS and JAXA TB, and the SSI mean value of SMOS TB is higher than that of JAXA TB for both daily and monthly time scale. It indicates that the big uncertainty of SMOS soil moisture products may raises from the unstable TB observation, which is highly contaminated by RFI and even cannot be removed at monthly scale.