Development of an Innovative Physical-Geometry-Based Soil Moisture Retrieval Method for CYGNSS Constellations

Global Navigation Satellite System-Reflectometry (GNSS-R) has evolved as an innovative remote sensing technique for Earth surface monitoring over the past three decades. While the Cyclone Global Navigation Satellite System (CYGNSS) constellation was initially designed to observe tropical cyclones, r...

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Main Authors: Xuerui Wu, Shumin Han, Xiaojuan Tian, Xinming Huang, Kuo Cao
Format: Article
Language:English
Published: IEEE 2025-01-01
Series:IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
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Online Access:https://ieeexplore.ieee.org/document/11026779/
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author Xuerui Wu
Shumin Han
Xiaojuan Tian
Xinming Huang
Kuo Cao
author_facet Xuerui Wu
Shumin Han
Xiaojuan Tian
Xinming Huang
Kuo Cao
author_sort Xuerui Wu
collection DOAJ
description Global Navigation Satellite System-Reflectometry (GNSS-R) has evolved as an innovative remote sensing technique for Earth surface monitoring over the past three decades. While the Cyclone Global Navigation Satellite System (CYGNSS) constellation was initially designed to observe tropical cyclones, recent studies highlight its untapped potential for soil moisture retrieval. In this work, we first analyze the physical scattering mechanisms of bare soil and vegetation, focusing on their distinct interactions with GNSS signals. A novel soil moisture retrieval method is proposed based on a zero-order scattering model. Surface reflectivity (SR) derived from CYGNSS is influenced by vegetation cover, surface roughness, and soil texture. To mitigate these effects, roughness-vegetation (R-V) correction factors are introduced. By removing R-V contributions from the SR, Fresnel reflectivity—directly linked to soil dielectric properties—is isolated for moisture estimation. In addition, simulations reveal that observation geometry significantly impacts SR variations; this geometric dependency is explicitly incorporated to refine retrieval accuracy. Validation demonstrates that integrating R-V correction and geometric adjustments reduces the root-mean-square error (RMSE) of soil moisture estimates from 0.0794 to 0.0357, marking a 55% improvement. This physics-based approach enhances CYGNSS-derived soil moisture precision and holds promise for advancing sustainable water resource management and meteorological studies through high-resolution, all-weather monitoring.
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institution Kabale University
issn 1939-1404
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publishDate 2025-01-01
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series IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
spelling doaj-art-23c81f0a6a604b459ed70bd63a8b6d342025-08-20T03:31:46ZengIEEEIEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing1939-14042151-15352025-01-0118174901749610.1109/JSTARS.2025.357072011026779Development of an Innovative Physical-Geometry-Based Soil Moisture Retrieval Method for CYGNSS ConstellationsXuerui Wu0https://orcid.org/0000-0002-2707-024XShumin Han1https://orcid.org/0009-0005-1817-998XXiaojuan Tian2https://orcid.org/0009-0005-7820-8359Xinming Huang3Kuo Cao4https://orcid.org/0000-0002-6361-3977Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai, ChinaDalian Maritime University, Dalian, ChinaSchool of Resources and Environmental Science and Engineering, Hubei University of Science and Technology, Xianning, ChinaCollege of Electronic Science and Technology, National University of Defense Technology, Changsha, ChinaCollege of Electronic Science and Technology, National University of Defense Technology, Changsha, ChinaGlobal Navigation Satellite System-Reflectometry (GNSS-R) has evolved as an innovative remote sensing technique for Earth surface monitoring over the past three decades. While the Cyclone Global Navigation Satellite System (CYGNSS) constellation was initially designed to observe tropical cyclones, recent studies highlight its untapped potential for soil moisture retrieval. In this work, we first analyze the physical scattering mechanisms of bare soil and vegetation, focusing on their distinct interactions with GNSS signals. A novel soil moisture retrieval method is proposed based on a zero-order scattering model. Surface reflectivity (SR) derived from CYGNSS is influenced by vegetation cover, surface roughness, and soil texture. To mitigate these effects, roughness-vegetation (R-V) correction factors are introduced. By removing R-V contributions from the SR, Fresnel reflectivity—directly linked to soil dielectric properties—is isolated for moisture estimation. In addition, simulations reveal that observation geometry significantly impacts SR variations; this geometric dependency is explicitly incorporated to refine retrieval accuracy. Validation demonstrates that integrating R-V correction and geometric adjustments reduces the root-mean-square error (RMSE) of soil moisture estimates from 0.0794 to 0.0357, marking a 55% improvement. This physics-based approach enhances CYGNSS-derived soil moisture precision and holds promise for advancing sustainable water resource management and meteorological studies through high-resolution, all-weather monitoring.https://ieeexplore.ieee.org/document/11026779/Cyclone Global Navigation Satellite System (CYGNSS)Global Navigation Satellite System-Reflectometry (GNSS-R)roughnesssoil moisturevegetation
spellingShingle Xuerui Wu
Shumin Han
Xiaojuan Tian
Xinming Huang
Kuo Cao
Development of an Innovative Physical-Geometry-Based Soil Moisture Retrieval Method for CYGNSS Constellations
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Cyclone Global Navigation Satellite System (CYGNSS)
Global Navigation Satellite System-Reflectometry (GNSS-R)
roughness
soil moisture
vegetation
title Development of an Innovative Physical-Geometry-Based Soil Moisture Retrieval Method for CYGNSS Constellations
title_full Development of an Innovative Physical-Geometry-Based Soil Moisture Retrieval Method for CYGNSS Constellations
title_fullStr Development of an Innovative Physical-Geometry-Based Soil Moisture Retrieval Method for CYGNSS Constellations
title_full_unstemmed Development of an Innovative Physical-Geometry-Based Soil Moisture Retrieval Method for CYGNSS Constellations
title_short Development of an Innovative Physical-Geometry-Based Soil Moisture Retrieval Method for CYGNSS Constellations
title_sort development of an innovative physical geometry based soil moisture retrieval method for cygnss constellations
topic Cyclone Global Navigation Satellite System (CYGNSS)
Global Navigation Satellite System-Reflectometry (GNSS-R)
roughness
soil moisture
vegetation
url https://ieeexplore.ieee.org/document/11026779/
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AT xiaojuantian developmentofaninnovativephysicalgeometrybasedsoilmoistureretrievalmethodforcygnssconstellations
AT xinminghuang developmentofaninnovativephysicalgeometrybasedsoilmoistureretrievalmethodforcygnssconstellations
AT kuocao developmentofaninnovativephysicalgeometrybasedsoilmoistureretrievalmethodforcygnssconstellations