{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,3]],"date-time":"2026-06-03T11:41:05Z","timestamp":1780486865309,"version":"3.54.1"},"reference-count":32,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2021,10,26]],"date-time":"2021-10-26T00:00:00Z","timestamp":1635206400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Jiangsu Agriculture Science and Technology Innovation Fund","award":["CX (21) 3068"],"award-info":[{"award-number":["CX (21) 3068"]}]},{"name":"Anhui Educational Commission Key Project","award":["KJ2020A00706"],"award-info":[{"award-number":["KJ2020A00706"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Global navigation satellite system interferometric reflectometry (GNSS-IR) represents an extra method to detect snow depth for climate research and water cycle managing. However, using a single frequency of GNSS-IR for snow depth retrieval is often found to be challenging when attempting to achieve a high spatial and temporal sensitivity. To evaluate both the capability of the GNSS-IR snow depth retrieved by the multi-GNSS system and multi-frequency from signal-to-noise ratio (SNR) data, the accuracy of snow depth retrieval by different frequency signals from the multi-GNSS system is analyzed, and a joint retrieval is carried out by combining the multi-GNSS system retrieval results. The SNR data of the global positioning system (GPS), global orbit navigation satellite system (GLONASS), Galileo satellite navigation system (Galileo), and BeiDou navigation satellite system (BDS) from the P387 station of the U.S. Plate Boundary Observatory (PBO) are analyzed. A Lomb\u2013Scargle periodogram (LSP) spectrum analysis is used to compare the difference in reflector height between the snow-free and snow surfaces in order to retrieve the snow depth, which is compared with the PBO snow depth. First, the different frequency retrieval results of the multi-GNSS system are analyzed. Then, the retrieval accuracy of the different GNSS systems is analyzed through multi-frequency mean fusion. Finally, the joint retrieval accuracy of the multi-GNSS system is analyzed through mean fusion. The experimental shows that the retrieval results of different frequencies of the multi-GNSS system have a strong correlation with the PBO snow depth, and that the accuracy is better than 10 cm. The multi-frequency mean fusion of different GNSS systems can effectively improve the retrieval accuracy, which is better than 7 cm. The joint retrieval accuracy of the multi-GNSS system is further improved, with a correlation coefficient (R) between the retrieval snow depth and the PBO snow depth of 0.99, and the accuracy is better than 3 cm. Therefore, using multi-GNSS and multi-frequency data to retrieve the snow depth has a good accuracy and feasibility.<\/jats:p>","DOI":"10.3390\/rs13214311","type":"journal-article","created":{"date-parts":[[2021,10,26]],"date-time":"2021-10-26T23:54:33Z","timestamp":1635292473000},"page":"4311","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["GNSS-IR Snow Depth Retrieval from Multi-GNSS and Multi-Frequency Data"],"prefix":"10.3390","volume":"13","author":[{"given":"Jinsheng","family":"Tu","sequence":"first","affiliation":[{"name":"College of Geographic Information and Tourism, Chuzhou University, Chuzhou 239000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5551-3079","authenticated-orcid":false,"given":"Haohan","family":"Wei","sequence":"additional","affiliation":[{"name":"College of Civil Engineering, Nanjing Forestry University, Nanjing 210037, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0809-7682","authenticated-orcid":false,"given":"Rui","family":"Zhang","sequence":"additional","affiliation":[{"name":"Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu 611756, China"},{"name":"State-Province Joint Engineering Laboratory of Spatial Information Technology for High-Speed Railway Safety, Southwest Jiaotong University, Chengdu 611756, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5702-5474","authenticated-orcid":false,"given":"Lei","family":"Yang","sequence":"additional","affiliation":[{"name":"College of Information Science and Engineering, Shandong Agricultural University, Tai\u2019an 271018, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2082-945X","authenticated-orcid":false,"given":"Jichao","family":"Lv","sequence":"additional","affiliation":[{"name":"Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu 611756, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaoming","family":"Li","sequence":"additional","affiliation":[{"name":"College of Surveying and Geoinformatics, Tongji University, Shanghai 200092, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shihai","family":"Nie","sequence":"additional","affiliation":[{"name":"College of Geographic Information and Tourism, Chuzhou University, Chuzhou 239000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8813-6601","authenticated-orcid":false,"given":"Peng","family":"Li","sequence":"additional","affiliation":[{"name":"College of Geographic Information and Tourism, Chuzhou University, Chuzhou 239000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yanxia","family":"Wang","sequence":"additional","affiliation":[{"name":"College of Geographic Information and Tourism, Chuzhou University, Chuzhou 239000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nan","family":"Li","sequence":"additional","affiliation":[{"name":"College of Geographic Information and Tourism, Chuzhou University, Chuzhou 239000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,10,26]]},"reference":[{"key":"ref_1","first-page":"50","article-title":"Snow cover and atmospheric variability: Changes in the snow covering the earth\u2019s surface affect both daily weather and long-term climate","volume":"72","author":"Walsh","year":"1984","journal-title":"Am. Sci."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"752","DOI":"10.1109\/JPROC.2009.2038947","article-title":"Cold Regions Hydrology High-Resolution Observatory for Snow and Cold Land Processes","volume":"98","author":"Rott","year":"2010","journal-title":"IEEE Proc."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"876","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_4","first-page":"172","article-title":"On Carrier Signal Multipath Effects in Relative GPS Positioning","volume":"13","author":"Georgiadou","year":"1988","journal-title":"Manuscr. Geod."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1007\/PL00012838","article-title":"Multipath Mitigation of Continuous GPS Measurements Using an Adaptive Filter","volume":"4","author":"Ge","year":"2000","journal-title":"GPS Solut."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"54","DOI":"10.2514\/2.4675","article-title":"Synergy between Global Positioning System Code, Carrier, and Signal-to-Noise Ratio Multipath Errors","volume":"24","author":"Ray","year":"2001","journal-title":"J. Guid. Control Dyn."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1","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":"6555","DOI":"10.1109\/TGRS.2013.2297681","article-title":"Inverse Modeling of GPS Multipath for Snow Depth Estimation\u2014Part I: Formulation and Simulations","volume":"52","author":"Nievinski","year":"2014","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"6564","DOI":"10.1109\/TGRS.2013.2297688","article-title":"Inverse Modeling of GPS Multipath for Snow Depth Estimation\u2014Part II: Application and Validation","volume":"52","author":"Nievinski","year":"2014","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1007\/s10291-014-0383-7","article-title":"Using geodetic GPS receivers to measure vegetation water content","volume":"19","author":"Wan","year":"2015","journal-title":"GPS Solut."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Larson, K.M., and Small, E.E. (2014). GPS ground networks for water cycle sensing. IEEE Geosci. Remote Sens. Symp., 3822\u20133825.","DOI":"10.1109\/IGARSS.2014.6947317"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"775","DOI":"10.1002\/wat2.1167","article-title":"GPS interferometric reflectometry: Applications to surface soil moisture, snow depth, and vegetation water content in the western United States","volume":"3","author":"Larson","year":"2016","journal-title":"Wiley Interdiscip. Rev. Water"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"41","DOI":"10.1007\/s10291-012-0259-7","article-title":"GPS snow sensing: Results from the EarthScope Plate Boundary Observatory","volume":"17","author":"Larson","year":"2013","journal-title":"GPS Solut."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"4802","DOI":"10.1109\/JSTARS.2015.2508673","article-title":"Estimation of Snow Depth Using L1 GPS Signal-to-Noise Ratio Data","volume":"9","author":"Larson","year":"2017","journal-title":"IEEE J. Sel. Top. Appl. Earth Observ. Remote Sens."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1104","DOI":"10.1016\/j.asr.2014.11.019","article-title":"Assessment of modernized GPS L5 SNR for ground-based multipath reflectometry applications","volume":"55","author":"Tabibi","year":"2015","journal-title":"Adv. Space Res."},{"key":"ref_16","unstructured":"Tabibi, S., Nievinski, F.G., and Dam, T.V. (2015, January 17). Multi-GNSS and multi-frequency SNR multipath reflectometry of snow depth, Trans EOS, G44A-07. Proceedings of the AGU Fall Meeting Abstract, San Francisco, CA, USA."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"3773","DOI":"10.1109\/TGRS.2017.2679899","article-title":"Statistical Comparison and Combination of GPS, GLONASS, and Multi-GNSS Multipath Reflectometry Applied to Snow Depth Retrieval","volume":"55","author":"Tabibi","year":"2017","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Jin, S., Qian, X., and Kutoglu, H. (2016). Snow Depth Variations Estimated from GPS-Reflectometry: A Case Study in Alaska from L2P SNR Data. Remote Sens., 8.","DOI":"10.3390\/rs8010063"},{"key":"ref_19","first-page":"889","article-title":"Monitoring snow depth based on the SNR signal of GLONASS satellites","volume":"22","author":"Zhou","year":"2018","journal-title":"J. Remote Sens."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"3814","DOI":"10.1038\/s41598-019-40456-2","article-title":"A new GPS SNR-Based Combination Approach for Land Surface Snow Depth Monitoring","volume":"9","author":"Zhou","year":"2019","journal-title":"Sci. Rep."},{"key":"ref_21","first-page":"8","article-title":"Snow depth detection and error analysis derived from SNR of GPS and BDS","volume":"47","author":"Wang","year":"2018","journal-title":"Acta Geod. Cartogr. Sin."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s10291-020-00990-3","article-title":"Analysis and combination of multi-GNSS snow depth retrievals in multipath reflectometry","volume":"24","author":"Wang","year":"2020","journal-title":"GPS Solut."},{"key":"ref_23","first-page":"77","article-title":"Observations of signal-to-noise ratios (SNR) at geodetic GPS site CASA: Implications for phase multipath","volume":"23","author":"Bilich","year":"2004","journal-title":"Proc. Cent. Eur. Geodyn. Seismol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"RS6003","DOI":"10.1029\/2007RS003652","article-title":"Mapping the GPS multipath environment using the signal-to-noise ratio (SNR)","volume":"42","author":"Bilich","year":"2007","journal-title":"Radio Sci."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s10291-021-01096-0","article-title":"GiRsnow: An open-source software for snow depth retrievals using GNSS interferometric reflectometry","volume":"25","author":"Zhang","year":"2021","journal-title":"GPS Solut."},{"key":"ref_26","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_27","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s10291-018-0744-8","article-title":"Software tools for GNSS interferometric reflectometry (GNSS-IR)","volume":"22","author":"Roesler","year":"2018","journal-title":"GPS Solut."},{"key":"ref_28","unstructured":"Axelrad, P., Larson, K., and Jones, B. (2005, January 13\u201316). Use of the correct satellite repeat period to characterize and reduce site-specific multipath errors. Proceedings of the ION GNSS 2005, Long Beach, CA, USA."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"447","DOI":"10.1007\/BF00648343","article-title":"Least-squares frequency analysis of unequally spaced data","volume":"39","author":"Lomb","year":"1976","journal-title":"Astrophys. Space Sci."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"835","DOI":"10.1086\/160554","article-title":"Studies in astronomical time series analysis. II\u2014Statistical aspects of spectral analysis of unevenly spaced data","volume":"263","author":"Scargle","year":"1982","journal-title":"Astrophys. J."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"2310","DOI":"10.1002\/2016JB013612","article-title":"Tropospheric delays in ground-based GNSS multipath reflectometry\u2014Experimental evidence from coastal sites","volume":"122","author":"Williams","year":"2017","journal-title":"J. Geophys. Res. Solid Earth."},{"key":"ref_32","first-page":"1168","article-title":"Retrieval of coastal typhoon storm surge using multi-GNSS-IR","volume":"49","author":"He","year":"2020","journal-title":"Acta Geod. Cartogr. Sin."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/21\/4311\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:24:24Z","timestamp":1760167464000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/21\/4311"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,10,26]]},"references-count":32,"journal-issue":{"issue":"21","published-online":{"date-parts":[[2021,11]]}},"alternative-id":["rs13214311"],"URL":"https:\/\/doi.org\/10.3390\/rs13214311","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,10,26]]}}}