{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T02:00:43Z","timestamp":1760234443076,"version":"build-2065373602"},"reference-count":52,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2021,5,21]],"date-time":"2021-05-21T00:00:00Z","timestamp":1621555200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Canadian Space Agency","award":["18FAYORA09"],"award-info":[{"award-number":["18FAYORA09"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>This paper describes a computation method for obtaining dielectric constant using Global Navigation Satellite System reflectometry (GNSS-R) products. Dielectric constant is a crucial component in the soil moisture retrieval process using reflected GNSS signals. The reflectivity for circular polarized signals is combined with the dielectric constant equation that is used for radiometer observations. Data from the Cyclone Global Navigation Satellite System (CYGNSS) mission, an eight-nanosatellite constellation for GNSS-R, are used for computing dielectric constant. Data from the Soil Moisture Active Passive (SMAP) mission are used to measure the soil moisture through its radiometer, and they are considered as a reference to confirm the accuracy of the new dielectric constant calculation method. The analyzed locations have been chosen that correspond to sites used for the calibration and validation of the SMAP soil moisture product using in-situ measurement data. The retrieved results, especially in the case of a specular point around Yanco, Australia, show that the estimated results track closely to the soil moisture results, and the Root Mean Square Error (RMSE) in the estimated dielectric constant is approximately 5.73. Similar results can be obtained when the specular point is located near the Texas Soil Moisture Network (TxSON), USA. These results indicate that the analysis procedure is well-defined, and it lays the foundation for obtaining quantitative soil moisture content using the GNSS reflectometry results. Future work will include applying the computation product to determine the characteristics that will allow for the separation of coherent and incoherent signals in delay Doppler maps, as well as to develop local soil moisture models.<\/jats:p>","DOI":"10.3390\/rs13112032","type":"journal-article","created":{"date-parts":[[2021,5,24]],"date-time":"2021-05-24T00:01:20Z","timestamp":1621814480000},"page":"2032","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Computation Approach for Quantitative Dielectric Constant from Time Sequential Data Observed by CYGNSS Satellites"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1100-8852","authenticated-orcid":false,"given":"Junchan","family":"Lee","sequence":"first","affiliation":[{"name":"Department of Earth and Space Science and Engineering, Lassonde School of Engineering, York University, Toronto, ON M3J 1P3, Canada"},{"name":"Satellite Technology Research Center, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sunil","family":"Bisnath","sequence":"additional","affiliation":[{"name":"Department of Earth and Space Science and Engineering, Lassonde School of Engineering, York University, Toronto, ON M3J 1P3, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Regina S.K.","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Earth and Space Science and Engineering, Lassonde School of Engineering, York University, Toronto, ON M3J 1P3, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Narin Gavili","family":"Kilane","sequence":"additional","affiliation":[{"name":"Department of Earth and Space Science and Engineering, Lassonde School of Engineering, York University, Toronto, ON M3J 1P3, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,5,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1155\/2013\/424178","article-title":"Remote Sensing of Soil Moisture","volume":"2013","author":"Lakshmi","year":"2013","journal-title":"ISRN Soil. Sci."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"781","DOI":"10.1109\/36.58964","article-title":"SSM\/I Instrument Evaluation","volume":"28","author":"Hollinger","year":"1990","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1655","DOI":"10.1109\/36.942543","article-title":"A Multifrequency Algorithm for the Retrieval of Soil Moisture on a Large Scale Using Microwave Data from SMMR and SSM\/I Satellites","volume":"39","author":"Paloscia","year":"2019","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"2626","DOI":"10.1109\/TGRS.2002.805077","article-title":"Sensitivity, Spatial Heterogeneity, and Scaling of C-Band Microwave Brightness Temperatures for Land Hydrology Studies","volume":"40","author":"Guha","year":"2002","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1482","DOI":"10.1109\/TGRS.2004.828193","article-title":"Use of the Scanning Multichannel Microwave Radiometer (SMMR) to Retrieve Soil Moisture and Surface Temperature over the Central United States","volume":"42","author":"Guha","year":"2004","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"57","DOI":"10.1016\/0022-1694(95)02968-0","article-title":"Radar Mapping of Surface Soil Moisture","volume":"184","author":"Ulaby","year":"1996","journal-title":"J. Hydrol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1367","DOI":"10.1016\/S0309-1708(02)00065-9","article-title":"Remote Sensing in Hydrology","volume":"25","author":"Schmugge","year":"2002","journal-title":"Adv. Water Resour."},{"key":"ref_8","first-page":"331","article-title":"A Passive Reflectometry and Interferometry System (PARIS): Applications to Ocean Altimetry","volume":"17","year":"1993","journal-title":"ESA J."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"50","DOI":"10.1109\/36.981349","article-title":"Wind Speed Measurement Using Forward Scattered GPS Signals","volume":"40","author":"Garrison","year":"2002","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"951","DOI":"10.1109\/36.841977","article-title":"Scattering of GPS Signals from the Ocean with Wind Remote Sensing Application","volume":"38","author":"Zavorotny","year":"2000","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"122","DOI":"10.1016\/j.rse.2012.05.012","article-title":"Characterization of Dry-Snow Sub-Structure Using GNSS Reflected Signals","volume":"124","author":"Cardellach","year":"2012","journal-title":"Remote Sens. Environ."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"4049","DOI":"10.1029\/2018GL077905","article-title":"Soil Moisture Sensing Using Spaceborne GNSS Reflections: Comparison of CYGNSS Reflectivity to SMAP Soil Moisture","volume":"45","author":"Chew","year":"2018","journal-title":"Geophys. Res. Lett."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"3317","DOI":"10.1002\/2016GL068189","article-title":"Demonstrating Soil Moisture Remote Sensing with Observations from the UK TechDemoSat-1 Satellite Mission","volume":"43","author":"Chew","year":"2016","journal-title":"Geophys. Res. Lett."},{"key":"ref_14","first-page":"4730","article-title":"Sensitivity of GNSS-R Spaceborne Observations to Soil Moisture and Vegetation","volume":"9","author":"Camps","year":"2016","journal-title":"IEEE J. Sel. Top. Appl."},{"key":"ref_15","first-page":"1522","article-title":"Airborne GNSS-R Polarimetric Measurements for Soil Moisture and Above-Ground Biomass Estimation","volume":"7","author":"Egido","year":"2014","journal-title":"IEEE J. Sel. Top. Appl."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1016\/j.rse.2005.09.015","article-title":"Utilizing Calibrated GPS Reflected Signals to Estimate Soil Reflectivity and Dielectric Constant: Results from SMEX02","volume":"100","author":"Katzberg","year":"2006","journal-title":"Remote Sens. Environ."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"3616","DOI":"10.1109\/TGRS.2009.2030672","article-title":"Soil Moisture Retrieval Using GNSS-R Techniques: Experimental Results Over a Bare Soil Field","volume":"47","author":"Camps","year":"2009","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_18","first-page":"4759","article-title":"Validation of GPS-IR Soil Moisture Retrievals: Comparison of Different Algorithms to Remove Vegetation Effects","volume":"9","author":"Small","year":"2016","journal-title":"IEEE J. Sel. Top. Appl."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1064","DOI":"10.1109\/LGRS.2016.2565380","article-title":"On the Spatial Resolution of GNSS Reflectometry","volume":"13","author":"Clarizia","year":"2016","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"4992","DOI":"10.1109\/TGRS.2013.2286257","article-title":"Consolidating the Precision of Interferometric GNSS-R Ocean Altimetry Using Airborne Experimental Data","volume":"52","author":"Cardellach","year":"2014","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_21","first-page":"102","article-title":"First Precise Spaceborne Sea Surface Altimetry with GNSS Reflected Signals","volume":"13","author":"Cardellach","year":"2019","journal-title":"IEEE J. Sel. Top. Appl."},{"key":"ref_22","unstructured":"Zavorotny, V.U., and Voronovich, A.G. (2000, January 24\u201328). Bistatic GPS Signal Reflections at Various Polarizations from Rough Land Surface with Moisture Content. Proceedings of the IEEE 2000 International Geoscience and Remote Sensing Symposium\u2014Taking the Pulse of the Planet: The Role of Remote Sensing in Managing the Environment, Honolulu, HI, USA."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1109\/TGRS.2010.2049023","article-title":"Land Geophysical Parameters Retrieval Using the Interference Pattern GNSS-R Technique","volume":"49","author":"Camps","year":"2011","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"385","DOI":"10.1175\/BAMS-D-14-00218.1","article-title":"New Ocean Winds Satellite Mission to Probe Hurricanes and Tropical Convection","volume":"97","author":"Ruf","year":"2016","journal-title":"Bull. Am. Meteorol. Soc."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"8272","DOI":"10.1029\/2018GL078923","article-title":"Use of Cyclone Global Navigation Satellite System (CyGNSS) Observations for Estimation of Soil Moisture","volume":"45","author":"Kim","year":"2018","journal-title":"Geophys. Res. Lett."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Guo, P., Shi, J., Gao, B., and Wan, H. (2016, January 10\u201315). Evaluation of Errors Induced by Soil Dielectric Models for Soil Moisture Retrieval at L-Band. Proceedings of the 2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Beijing, China.","DOI":"10.1109\/IGARSS.2016.7729429"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Yang, T., Wan, W., Sun, Z., Liu, B., Li, S., and Chen, X. (2020). Comprehensive Evaluation of Using TechDemoSat-1 and CYGNSS Data to Estimate Soil Moisture over Mainland China. Remote Sens., 12.","DOI":"10.3390\/rs12111699"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1109\/TGRS.1985.289497","article-title":"Microwave Dielectric Behavior of Wet Soil-Part 1: Empirical Models and Experimental Observations","volume":"GE-23","author":"Hallikainen","year":"1985","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1109\/TGRS.1985.289498","article-title":"Microwave Dielectric Behavior of Wet Soil-Part II: Dielectric Mixing Models","volume":"GE-23","author":"Dobson","year":"1985","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_30","first-page":"4752","article-title":"Estimation of Surface Characteristics Using GNSS LH-Reflected Signals: Land Versus Water","volume":"9","author":"Jia","year":"2016","journal-title":"IEEE J. Sel. Top. Appl."},{"key":"ref_31","unstructured":"Egido, A., Ruffini, G., Caparrini, M., Martin, C., Farres, E., and Banque, X. (2008). Soil moisture monitorization using gnss reflected signals. arXiv."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1016\/j.rse.2017.01.021","article-title":"Validation of SMAP Surface Soil Moisture Products with Core Validation Sites","volume":"191","author":"Colliander","year":"2017","journal-title":"Remote Sens. Environ."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"6542","DOI":"10.1109\/TGRS.2013.2297572","article-title":"SAVERS: A Simulator of GNSS Reflections from Bare and Vegetated Soils","volume":"52","author":"Pierdicca","year":"2014","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"L12401","DOI":"10.1029\/2010GL042951","article-title":"Sensing Vegetation Growth with Reflected GPS Signals","volume":"37","author":"Small","year":"2010","journal-title":"Geophys. Res. Lett."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Hu, C., Benson, C., Park, H., Camps, A., Qiao, L., and Rizos, C. (2019). Detecting Targets above the Earth\u2019s Surface Using GNSS-R Delay Doppler Maps: Results from TDS-1. Remote Sens., 11.","DOI":"10.3390\/rs11192327"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"832","DOI":"10.1175\/2010JHM1223.1","article-title":"Performance Metrics for Soil Moisture Retrievals and Application Requirements","volume":"11","author":"Entekhabi","year":"2010","journal-title":"J. Hydrometeorol."},{"key":"ref_37","unstructured":"(2021, May 15). SMAP L3 Radiometer Global Daily 36 Km EASE-Grid Soil Moisture, Version 6. Available online: https:\/\/nsidc.org\/data\/SPL3SMP\/versions\/6."},{"key":"ref_38","unstructured":"O\u2019Neill, P.E., Chan, S., Njoku, E.G., Jackson, T., Bindlish, R., and Chaubell, J. (2019, August 15). SMAP L3 Radiometer Global Daily 36 Km EASE-Grid Soil Moisture, Version 6. Available online: https:\/\/doi.org\/10.5067\/EVYDQ32FNWTH."},{"key":"ref_39","unstructured":"(2018, May 14). PO.DAAC, Available online: https:\/\/podaac.jpl.nasa.gov\/."},{"key":"ref_40","unstructured":"Ruf, C., Chang, P.S., Clarizia, M.-P., Gleason, S., Jelenak, Z., Majumdar, S., Morris, M., Murray, J., Musko, S., and Posselt, D. (2016). CYGNSS Handbook Cyclone Global Navigation Satellite System: Deriving Surface Wind Speeds in Tropical Cyclones."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"333","DOI":"10.1016\/j.rse.2017.06.020","article-title":"SMAP Radar Receiver Measures Land Surface Freeze\/Thaw State through Capture of Forward-Scattered L-Band Signals","volume":"198","author":"Chew","year":"2017","journal-title":"Remote Sens. Environ."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"4322","DOI":"10.1109\/TGRS.2018.2890646","article-title":"Time-Series Retrieval of Soil Moisture Using CYGNSS","volume":"57","author":"Johnson","year":"2019","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Calabia, A., Molina, I., and Jin, S. (2020). Soil Moisture Content from GNSS Reflectometry Using Dielectric Permittivity from Fresnel Reflection Coefficients. Remote Sens., 12.","DOI":"10.3390\/rs12010122"},{"key":"ref_44","first-page":"2227","article-title":"Analysis of CYGNSS Data for Soil Moisture Retrieval","volume":"12","author":"Clarizia","year":"2019","journal-title":"IEEE J. Sel. Top. Appl."},{"key":"ref_45","unstructured":"Jarvis, A., Reuter, H.I., Nelson, A., and Guevara, E. (2021, May 05). Hole-Filled Seamless SRTM Data V4. Available online: http:\/\/srtm.csi.cgiar.org\/."},{"key":"ref_46","unstructured":"Stutzman, W.L. (1993). Polarization in Electromagnetic Systems, Artech House."},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Griffiths, D.J. (2017). Introduction to Electrodynamics, Cambridge University Press.","DOI":"10.1017\/9781108333511"},{"key":"ref_48","first-page":"23","article-title":"Soil Moisture Algorithm Validation Using Data from the Advanced Microwave Scanning Radiometer (AMSR-E) in Mongolia","volume":"30","author":"Jackson","year":"2004","journal-title":"Ital. J. Remote Sens."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"32","DOI":"10.3390\/ijgi1010032","article-title":"EASE-Grid 2.0: Incremental but Significant Improvements for Earth-Gridded Data Sets","volume":"1","author":"Brodzik","year":"2012","journal-title":"ISPRS Int. Geo-inf."},{"key":"ref_50","first-page":"1218","article-title":"Space-Borne GNSS-R Signal Over a Complex Topography: Modeling and Validation","volume":"13","author":"Dente","year":"2019","journal-title":"IEEE J. Sel. Top. Appl."},{"key":"ref_51","unstructured":"National Snow & Ice Data Center (2019, June 27). Update: SMAP in Safe Mode. Available online: https:\/\/nsidc.org\/the-drift\/data-update\/update-smap-in-safe-mode\/."},{"key":"ref_52","first-page":"2996","article-title":"Monitoring Freeze-Thaw State by Means of GNSS Reflectometry: An Analysis of TechDemoSat-1 Data","volume":"13","author":"Comite","year":"2019","journal-title":"IEEE J. Sel. Top. Appl."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/11\/2032\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T06:05:28Z","timestamp":1760162728000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/11\/2032"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,5,21]]},"references-count":52,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2021,6]]}},"alternative-id":["rs13112032"],"URL":"https:\/\/doi.org\/10.3390\/rs13112032","relation":{},"ISSN":["2072-4292"],"issn-type":[{"type":"electronic","value":"2072-4292"}],"subject":[],"published":{"date-parts":[[2021,5,21]]}}}