Evaluation of SMOS soil moisture retrievals over the central United States for hydro-meteorological application

Publication date: Available online 2 July 2015 Source:Physics and Chemistry of the Earth, Parts A/B/C Author(s): Lu Zhuo , Qiang Dai , Dawei Han Soil moisture has been widely recognized as a key variable in hydro-meteorological processes and plays an important role in hydrological modelling. Remote sensing techniques have improved the availability of soil moisture data, however, most previous studies have only focused on the evaluation of retrieved data against point-based observations using only one overpass (i.e., the ascending orbit). Recently, the global Level-3 soil moisture dataset generated from Soil Moisture and Ocean Salinity (SMOS) observations was released by the Barcelona Expert Center. To address the aforementioned issues, this study is particularly focused on a basin scale evaluation in which the soil moisture deficit is derived from a three-layer Xinanjiang model used as a hydrological benchmark for all comparisons. In addition, both ascending and descending overpasses were analyzed for a more comprehensive comparison. It was interesting to find that the SMOS soil moisture accuracy did not improve with time as we would have expected. Furthermore, none of the overpasses provided reliable soil moisture estimates during the frozen season, especially for the ascending orbit. When frozen periods were removed, both overpasses showed significant improvements (i.e., the correlations increased from r = –0.53 to r = –0.65 and from r = –0.62 to r = –0.70 fo...

Source: Physics and Chemistry of the Earth, Parts ABC - July 2, 2015 Category: Science Source Type: research