Validation of Five Passive Microwave Remotely Sensed Soil Moisture Products over the Qinghai-Tibet Plateau, China

High-quality and long-term soil moisture (SM) products are crucial for studying the climate change over the Qinghai-Tibet Plateau. Five passive microwave remotely sensed SM products were compared against in-situ SM observations from five networks, i.e., Heihe, Naqu, Pali, Maqu, and Ngari. Five SM products include the Soil Moisture Active Passive (SMAP), the Soil Moisture and Ocean Salinity (SMOS), the Fengyun-3B (FY3B), the Land Parameter Retrieval Model (LPRM), and the Japan Aerospace Exploration Agency (JAXA). The results show that SMAP performs better than other four products in every network, but it has a slightly underestimate and poor dynamic range in Heihe network, which mainly due to the significant heterogeneity of topography and land cover. Moreover, the underestimate for JAXA, the overestimate for LPRM, the noisy temporal variations for SMOS, good dynamic changes for FY3B but lacks perfect absolute accuracy, all of these can be reflected from the validation results.