{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,16]],"date-time":"2026-01-16T03:26:29Z","timestamp":1768533989190,"version":"3.49.0"},"reference-count":34,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2021,5,10]],"date-time":"2021-05-10T00:00:00Z","timestamp":1620604800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"CNES\/EUMETSAT OSTST FOAM","award":["PNTS GRAEL"],"award-info":[{"award-number":["PNTS GRAEL"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Signal-to-noise ratio (SNR) time series acquired by a geodetic antenna were analyzed to retrieve water heights during asymmetric tides on a narrow river using the Interference Pattern Technique (IPT) from Global Navigation Satellite System Reflectometry (GNSS-R). The dynamic SNR method was selected because the elevation rate of the reflecting surface during rising tides is high in the Garonne River with macro tidal conditions. A new process was developed to filter out the noise introduced by the environmental conditions on the reflected signal due to the narrowness of the river compared to the size of the Fresnel areas, the presence of vegetation on the river banks, and the presence of boats causing multiple reflections. This process involved the removal of multipeaks in the Lomb-Scargle Periodogram (LSP) output and an iterative least square estimation (LSE) of the output heights. Evaluation of the results was performed against pressure-derived water heights. The best results were obtained using all GNSS bands (L1, L2, and L5) simultaneously: R = 0.99, ubRMSD = 0.31 m. We showed that the quality of the retrieved heights was consistent, whatever the vertical velocity of the reflecting surface, and was highly dependent on the number of satellites visible. The sampling period of our solution was 1 min with a 5-min moving window, and no tide models or fit were used in the inversion process. This highlights the potential of the dynamic SNR method to detect and monitor extreme events with GNSS-R, including those affecting inland waters such as flash floods.<\/jats:p>","DOI":"10.3390\/rs13091856","type":"journal-article","created":{"date-parts":[[2021,5,10]],"date-time":"2021-05-10T10:49:51Z","timestamp":1620643791000},"page":"1856","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["SNR-Based Water Height Retrieval in Rivers: Application to High Amplitude Asymmetric Tides in the Garonne River"],"prefix":"10.3390","volume":"13","author":[{"given":"Pierre","family":"Zeiger","sequence":"first","affiliation":[{"name":"LEGOS, UMR 5566, OMP, Universit\u00e9 Paul Sabatier, 31400 Toulouse, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4661-8274","authenticated-orcid":false,"given":"Fr\u00e9d\u00e9ric","family":"Frappart","sequence":"additional","affiliation":[{"name":"LEGOS, UMR 5566, OMP, Universit\u00e9 Paul Sabatier, 31400 Toulouse, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1750-2819","authenticated-orcid":false,"given":"Jos\u00e9","family":"Darrozes","sequence":"additional","affiliation":[{"name":"GET, UMR 5563, OMP, Universit\u00e9 Paul Sabatier, 31400 Toulouse, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nicolas","family":"Roussel","sequence":"additional","affiliation":[{"name":"Navigation &amp; ATM Chains, Airbus Defence and Space, 31400 Toulouse, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Philippe","family":"Bonneton","sequence":"additional","affiliation":[{"name":"EPOC, UMR 5805, CNRS, Universit\u00e9 de Bordeaux, 33600 Pessac, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Natalie","family":"Bonneton","sequence":"additional","affiliation":[{"name":"EPOC, UMR 5805, CNRS, Universit\u00e9 de Bordeaux, 33600 Pessac, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Guillaume","family":"Detandt","sequence":"additional","affiliation":[{"name":"EPOC, UMR 5805, CNRS, Universit\u00e9 de Bordeaux, 33600 Pessac, France"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,5,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"15787","DOI":"10.1029\/92JD01517","article-title":"GPS Meteorology: Remote Sensing of Atmospheric Water Vapor Using the Global Positioning System","volume":"97","author":"Bevis","year":"1992","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"4552","DOI":"10.1109\/JSTARS.2016.2614428","article-title":"GEROS-ISS: GNSS REflectometry, Radio Occultation, and Scatterometry Onboard the International Space Station","volume":"9","author":"Wickert","year":"2016","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"4843","DOI":"10.1109\/JSTARS.2016.2568742","article-title":"Reflectometry With an Open-Source Software GNSS Receiver: Use Case With Carrier Phase Altimetry","volume":"9","author":"Lestarquit","year":"2016","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Hall, C.D., and Cordey, R.A. (1988, January 12\u201316). Multistatic Scatterometry. Proceedings of the IEEE International Geoscience and Remote Sensing Symposium, Edinburgh, UK.","DOI":"10.1109\/IGARSS.1988.570200"},{"key":"ref_5","first-page":"331","article-title":"A Passive Reflectometry and Interferometry System (PARIS): Application to Ocean Altimetry","volume":"17","year":"1993","journal-title":"ESA J."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"254","DOI":"10.1049\/el:19980180","article-title":"Using GPS to Measure Ground Complex Permittivity","volume":"34","author":"Kavak","year":"1998","journal-title":"Electron. Lett."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"L24405","DOI":"10.1029\/2008GL036013","article-title":"Use of GPS Receivers as a Soil Moisture Network for Water Cycle Studies","volume":"35","author":"Larson","year":"2008","journal-title":"Geophys. Res. Lett."},{"key":"ref_8","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_9","doi-asserted-by":"crossref","first-page":"537","DOI":"10.1109\/TGRS.2013.2242332","article-title":"Effects of Near-Surface Soil Moisture on GPS SNR Data: Development of a Retrieval Algorithm for Soil Moisture","volume":"52","author":"Chew","year":"2014","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"4781","DOI":"10.1109\/JSTARS.2016.2537847","article-title":"Detection of Soil Moisture Variations Using GPS and GLONASS SNR Data for Elevation Angles Ranging from 2\u00b0 to 70\u00b0","volume":"9","author":"Roussel","year":"2016","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1931","DOI":"10.5194\/hess-22-1931-2018","article-title":"Deriving Surface Soil Moisture from Reflected GNSS Signal Observations from a Grassland Site in Southwestern France","volume":"22","author":"Zhang","year":"2018","journal-title":"Hydrol. Earth Syst. Sci."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"L17502","DOI":"10.1029\/2009GL039430","article-title":"Can We Measure Snow Depth with GPS Receivers?","volume":"36","author":"Larson","year":"2009","journal-title":"Geophys. Res. Lett."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1109","DOI":"10.1109\/LGRS.2012.2190379","article-title":"Snow Thickness Monitoring Using GNSS Measurements","volume":"9","author":"Aguasca","year":"2012","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_14","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_15","doi-asserted-by":"crossref","first-page":"4767","DOI":"10.5194\/hess-21-4767-2017","article-title":"Use of Reflected GNSS SNR Data to Retrieve Either Soil Moisture or Vegetation Height from a Wheat Crop","volume":"21","author":"Zhang","year":"2017","journal-title":"Hydrol. Earth Syst. Sci."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1118","DOI":"10.1175\/1520-0426(2000)017<1118:DOWLAT>2.0.CO;2","article-title":"Determination of Water Level and Tides Using Interferometric Observations of GPS Signals","volume":"17","author":"Anderson","year":"2000","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1200","DOI":"10.1109\/LGRS.2012.2236075","article-title":"The Accidental Tide Gauge: A GPS Reflection Case Study From Kachemak Bay, Alaska","volume":"10","author":"Larson","year":"2013","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"50","DOI":"10.1186\/1687-6180-2014-50","article-title":"Sea Level Measurements Using Multi-Frequency GPS and GLONASS Observations","volume":"2014","author":"Haas","year":"2014","journal-title":"EURASIP J. Adv. Signal Process."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Vu, P.L., Ha, M.C., Frappart, F., Darrozes, J., Ramillien, G., Dufrechou, G., Gegout, P., Morichon, D., and Bonneton, P. (2019). Identifying 2010 Xynthia Storm Signature in GNSS-R-Based Tide Records. Remote Sens., 11.","DOI":"10.3390\/rs11070782"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"4419","DOI":"10.1109\/JSTARS.2020.3010413","article-title":"Quantifying the Uncertainty in Ground-Based GNSS-Reflectometry Sea Level Measurements","volume":"13","author":"Purnell","year":"2020","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"111959","DOI":"10.1016\/j.rse.2020.111959","article-title":"Tidal Analysis of GNSS Reflectometry Applied for Coastal Sea Level Sensing in Antarctica and Greenland","volume":"248","author":"Tabibi","year":"2020","journal-title":"Remote Sens. Environ."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"70","DOI":"10.1007\/s00190-020-01387-3","article-title":"SNR-Based GNSS Reflectometry for Coastal Sea-Level Altimetry: Results from the First IAG Inter-Comparison Campaign","volume":"94","author":"Hobiger","year":"2020","journal-title":"J. Geod."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1301","DOI":"10.1016\/j.asr.2012.04.017","article-title":"Coastal Sea Level Measurements Using a Single Geodetic GPS Receiver","volume":"51","author":"Larson","year":"2013","journal-title":"Adv. Space Res."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Beckheinrich, J., Hirrle, A., Schon, S., Beyerle, G., Semmling, M., and Wickert, J. (2014, January 13\u201318). Water Level Monitoring of the Mekong Delta Using GNSS Reflectometry Technique. Proceedings of the 2014 IEEE Geoscience and Remote Sensing Symposium, Quebec City, QC, Canada.","DOI":"10.1109\/IGARSS.2014.6947311"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Tabibi, S., and Francis, O. (2020). Can GNSS-R Detect Abrupt Water Level Changes?. Remote Sens., 12.","DOI":"10.3390\/rs12213614"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"923","DOI":"10.1002\/2014JC010267","article-title":"Tidal Bore Dynamics in Funnel-Shaped Estuaries","volume":"120","author":"Bonneton","year":"2015","journal-title":"J. Geophys. Res. Ocean."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Martins, K., Bonneton, P., Frappart, F., Detandt, G., Bonneton, N., and Blenkinsopp, C.E. (2017). High Frequency Field Measurements of an Undular Bore Using a 2D LiDAR Scanner. Remote Sens., 9.","DOI":"10.3390\/rs9050462"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"917","DOI":"10.5721\/EuJRS20164948","article-title":"High Rate GNSS Measurements for Detecting Non-Hydrostatic Surface Wave. Application to Tidal Borein the Garonne River","volume":"49","author":"Frappart","year":"2016","journal-title":"Eur. J. Remote Sens."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1016\/j.rse.2015.10.011","article-title":"Sea Level Monitoring and Sea State Estimate Using a Single Geodetic Receiver","volume":"171","author":"Roussel","year":"2015","journal-title":"Remote Sens. Environ."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Vu, P.-L., Frappart, F., Darrozes, J., Ha, M.-C., Dinh, T.-B.-H., and Ramillien, G. (2018, January 22\u201327). Comparison of Water Level Changes in the Mekong River Using Gnss Reflectometry, Satellite Altimetry and in-Situ Tide\/River Gauges. Proceedings of the IGARSS 2018\u20142018 IEEE International Geoscience and Remote Sensing Symposium, Valencia, Spain.","DOI":"10.1109\/IGARSS.2018.8518977"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"121","DOI":"10.1016\/j.ecss.2016.01.019","article-title":"Conditions for Tidal Bore Formation in Convergent Alluvial Estuaries","volume":"172","author":"Bonneton","year":"2016","journal-title":"Estuar. Coast. Shelf Sci."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"388","DOI":"10.1029\/RS020i003p00388","article-title":"Multipath Effects on the Determination of Absolute Ionospheric Time Delay from GPS Signals","volume":"20","author":"Bishop","year":"1985","journal-title":"Radio Sci."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1286","DOI":"10.1002\/2016RS006057","article-title":"Improving GNSS-R Sea Level Determination through Inverse Modeling of SNR Data: GNSS-R INVERSE MODELING","volume":"51","author":"Strandberg","year":"2016","journal-title":"Radio Sci."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"241","DOI":"10.1007\/s00190-014-0784-y","article-title":"Levelling Co-Located GNSS and Tide Gauge Stations Using GNSS Reflectometry","volume":"89","author":"Watson","year":"2015","journal-title":"J. Geod."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/9\/1856\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:58:50Z","timestamp":1760162330000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/9\/1856"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,5,10]]},"references-count":34,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2021,5]]}},"alternative-id":["rs13091856"],"URL":"https:\/\/doi.org\/10.3390\/rs13091856","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,5,10]]}}}