{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:37:13Z","timestamp":1760240233058,"version":"build-2065373602"},"reference-count":28,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2019,4,22]],"date-time":"2019-04-22T00:00:00Z","timestamp":1555891200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this paper, the SOMOSTA (Soil Moisture Monitoring Station) experiment on the intercomparison of soil moisture monitoring from Global Navigation Satellite System Reflectometry (GNSS-R) signals and passive L-band microwave radiometer observations at the Valencia Anchor Station is introduced. The GNSS-R instrument has an up-looking antenna for receiving direct signals from satellites, and a dual-pol down-looking antenna for receiving LHCP (left-hand circular polarization) and RHCP (right-hand circular polarization) reflected signals from the soil surface. Data were collected from the three different antennas through the two channels of Oceanpal GNSS-R receiver and, in addition, calibration was performed to reduce the impact from the differing channels. Reflectivity was thus measured, and soil moisture could be retrieved. The ESA (European Space Agency)-funded ELBARA-II (ESA L Band Radiometer II) is an L-band radiometer with two channels with 11 MHz bandwidth and respective center frequencies of 1407.5 MHz and 1419.5 MHz. The ELBARAII antenna is a large dual-mode Picket horn that is 1.4 m wide, with a length of 2.7 m with \u22123 dB full beam width of 12\u00b0 (\u00b16\u00b0 around the antenna main direction) and a gain of 23.5 dB. By comparing GNSS-R and ELBARA-II radiometer data, a high correlation was found between the LHCP reflectivity measured by GNSS-R and the horizontal\/vertical reflectivity from the radiometer (with correlation coefficients ranging from 0.83 to 0.91). Neural net fitting was used for GNSS-R soil moisture inversion, and the RMSE (Root Mean Square Error) was 0.014 m3\/m3. The determination coefficient between the retrieved soil moisture and in situ measurements was R2 = 0.90 for Oceanpal and R2 = 0.65 for Elbara II, and the ubRMSE (Unbiased RMSE) were 0.0128 and 0.0734 respectively. The soil moisture retrievals by both L-band remote sensing methods show good agreement with each other, and their mutual correspondence with in-situ measurements and with rainfall was also good. <\/jats:p>","DOI":"10.3390\/s19081900","type":"journal-article","created":{"date-parts":[[2019,4,22]],"date-time":"2019-04-22T11:02:53Z","timestamp":1555930973000},"page":"1900","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Intercomparison of Soil Moisture Retrieved from GNSS-R and from Passive L-Band Radiometry at the Valencia Anchor Station"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0238-4568","authenticated-orcid":false,"given":"Cong","family":"Yin","sequence":"first","affiliation":[{"name":"Department of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China"},{"name":"Meteorological Observation Centre, China Meteorological Administration, Beijing 100081, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2044-2194","authenticated-orcid":false,"given":"Ernesto","family":"Lopez-Baeza","sequence":"additional","affiliation":[{"name":"Faculty of Physics, Earth Physics and Thermodynamics Department, Climatology from Satellites Group, University of Valencia, Burjassot, 46100 Valencia, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7626-7033","authenticated-orcid":false,"given":"Manuel","family":"Martin-Neira","sequence":"additional","affiliation":[{"name":"European Space Agency, ESA-ESTEC, 2200 AG Noordwijk, The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8121-768X","authenticated-orcid":false,"given":"Roberto","family":"Fernandez-Moran","sequence":"additional","affiliation":[{"name":"Faculty of Physics, Earth Physics and Thermodynamics Department, Climatology from Satellites Group, University of Valencia, Burjassot, 46100 Valencia, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"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":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8365-0233","authenticated-orcid":false,"given":"Enrique A.","family":"Navarro-Camba","sequence":"additional","affiliation":[{"name":"IRTIC, University of Valencia, C\/. Catedr\u00e1tico Jos\u00e9 Beltr\u00e1n, 2, 46980 Paterna, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Alejandro","family":"Egido","sequence":"additional","affiliation":[{"name":"Starlab-Living Science, 08035 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Antonio","family":"Mollfulleda","sequence":"additional","affiliation":[{"name":"Starlab-Living Science, 08035 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6215-7607","authenticated-orcid":false,"given":"Weiqiang","family":"Li","sequence":"additional","affiliation":[{"name":"Earth Observation Research Group, Institute of Space Sciences (ICE, CSIC), 08193 Barcelona, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yunchang","family":"Cao","sequence":"additional","affiliation":[{"name":"Meteorological Observation Centre, China Meteorological Administration, Beijing 100081, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bin","family":"Zhu","sequence":"additional","affiliation":[{"name":"Department of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing 210044, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dongkai","family":"Yang","sequence":"additional","affiliation":[{"name":"School of Electronic and Information Engineering, Beihang University, Beijing 100083, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,4,22]]},"reference":[{"key":"ref_1","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_2","unstructured":"Zavorotny, V.U., and Voronovich, A.G. 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