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Validation of SMOS Soil Moisture Products over the Maqu and Twente Regions
Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, Hengelosestraat 99, 7514AE Enschede, The Netherlands
Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions, Cold and Arid Regions Environmental and Engineering Research Institute (CAREERI), Chinese Academy of Sciences, Lanzhou 730000, China
* Author to whom correspondence should be addressed.
Received: 4 June 2012; in revised form: 4 July 2012 / Accepted: 18 July 2012 / Published: 25 July 2012
Abstract: The validation of Soil Moisture and Ocean Salinity (SMOS) soil moisture products is a crucial step in the investigation of their inaccuracies and limitations, before planning further refinements of the retrieval algorithm. Therefore, this study intended to contribute to the validation of the SMOS soil moisture products, by comparing them with the data collected in situ in the Maqu (China) and Twente (The Netherlands) regions in 2010. The seasonal behavior of the SMOS soil moisture products is generally in agreement with the in situ measurements for both regions. However, the validation analysis resulted in determination coefficients of 0.55 and 0.51 over the Maqu and Twente region, respectively, for the ascending pass data, and of 0.24 and 0.41, respectively, for the descending pass data. Moreover, a systematic dry bias of the SMOS soil moisture was found of approximately 0.13 m3/m3 for the Maqu region and 0.17 m3/m3 for the Twente region for ascending pass data. Several factors might have affected the retrieval accuracy, such as the presence of Radio Frequency Interference (RFI), the use of inaccurate land cover information and the presence of frozen soils not correctly detected in winter. Improving the RFI filtering method and the quality of the retrieval algorithm inputs, such as land surface temperature and land cover, would certainly improve the accuracy of the retrieved soil moisture.
Keywords: soil moisture; SMOS; validation; Tibetan Plateau; Maqu; Twente
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MDPI and ACS Style
Dente, L.; Su, Z.; Wen, J. Validation of SMOS Soil Moisture Products over the Maqu and Twente Regions. Sensors 2012, 12, 9965-9986.
Dente L, Su Z, Wen J. Validation of SMOS Soil Moisture Products over the Maqu and Twente Regions. Sensors. 2012; 12(8):9965-9986.
Dente, Laura; Su, Zhongbo; Wen, Jun. 2012. "Validation of SMOS Soil Moisture Products over the Maqu and Twente Regions." Sensors 12, no. 8: 9965-9986.