{"title":"In-situ and triple collocation-based evaluations of Tianmu-1 global soil moisture products","authors":"Qingyun Wang, Cuixian Lu, Yuxin Zheng, Zhuo Wang, Jiafeng Li, Yini Tan","doi":"10.1016/j.rse.2025.114892","DOIUrl":null,"url":null,"abstract":"<div><div>Global Navigation Satellite System-Reflectometry (GNSS-R), as a favorable technology to provide large-scale soil moisture estimates, contributes to studies in climatology, hydrology, and agriculture. The Tianmu-1 Meteorological Mission (TM-1), currently runs 23 satellites in orbit (including one experimental satellite) with multi-GNSS compatibility, achieve shorter revisit periods and higher data acquisition frequencies compared with single-satellite missions. The hourly TM-1 surface soil moisture (SSM) products, offer affluent information for global soil moisture monitoring. This study provides the first comprehensive characterization and performance evaluation of TM-1 SSM products based on in-situ measurements and products of Soil Moisture Active Passive (SMAP), European Space Agency Climate Change Initiative (ESA CCI), and Global Land Data Assimilation System (GLDAS). The TM-1 SSM demonstrates expected spatiotemporal patterns at both regional and global scales. The in-situ validation results reveal its landcover-dependent accuracy, with superior performance over bare soils (unbiased Root Mean Square Error, ubRMSE of about 0.02 m<sup>3</sup>/m<sup>3</sup>) compared to vegetated regions (ubRMSE of around 0.07 m<sup>3</sup>/m<sup>3</sup>). Furthermore, Extended Triple Collocation (ETC) assessments using (1) TM-1, active, and ground observations and (2) TM-1, model, and ground observations triplets are conducted. The ETC-derived results present that TM-1 SSM achieve global correlation coefficient of 0.75 and random error standard deviation of 0.035 m<sup>3</sup>/m<sup>3</sup>. Overall, this study demonstrates the reliable accuracy of TM-1 SSM product, and provides valuable insights for its refinement and potential applications.</div></div>","PeriodicalId":417,"journal":{"name":"Remote Sensing of Environment","volume":"328 ","pages":"Article 114892"},"PeriodicalIF":11.4000,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Remote Sensing of Environment","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0034425725002962","RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENVIRONMENTAL SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Global Navigation Satellite System-Reflectometry (GNSS-R), as a favorable technology to provide large-scale soil moisture estimates, contributes to studies in climatology, hydrology, and agriculture. The Tianmu-1 Meteorological Mission (TM-1), currently runs 23 satellites in orbit (including one experimental satellite) with multi-GNSS compatibility, achieve shorter revisit periods and higher data acquisition frequencies compared with single-satellite missions. The hourly TM-1 surface soil moisture (SSM) products, offer affluent information for global soil moisture monitoring. This study provides the first comprehensive characterization and performance evaluation of TM-1 SSM products based on in-situ measurements and products of Soil Moisture Active Passive (SMAP), European Space Agency Climate Change Initiative (ESA CCI), and Global Land Data Assimilation System (GLDAS). The TM-1 SSM demonstrates expected spatiotemporal patterns at both regional and global scales. The in-situ validation results reveal its landcover-dependent accuracy, with superior performance over bare soils (unbiased Root Mean Square Error, ubRMSE of about 0.02 m3/m3) compared to vegetated regions (ubRMSE of around 0.07 m3/m3). Furthermore, Extended Triple Collocation (ETC) assessments using (1) TM-1, active, and ground observations and (2) TM-1, model, and ground observations triplets are conducted. The ETC-derived results present that TM-1 SSM achieve global correlation coefficient of 0.75 and random error standard deviation of 0.035 m3/m3. Overall, this study demonstrates the reliable accuracy of TM-1 SSM product, and provides valuable insights for its refinement and potential applications.
期刊介绍:
Remote Sensing of Environment (RSE) serves the Earth observation community by disseminating results on the theory, science, applications, and technology that contribute to advancing the field of remote sensing. With a thoroughly interdisciplinary approach, RSE encompasses terrestrial, oceanic, and atmospheric sensing.
The journal emphasizes biophysical and quantitative approaches to remote sensing at local to global scales, covering a diverse range of applications and techniques.
RSE serves as a vital platform for the exchange of knowledge and advancements in the dynamic field of remote sensing.