{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,7]],"date-time":"2026-04-07T16:24:39Z","timestamp":1775579079756,"version":"3.50.1"},"reference-count":41,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2020,8,12]],"date-time":"2020-08-12T00:00:00Z","timestamp":1597190400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000844","name":"European Space Agency","doi-asserted-by":"publisher","award":["4000129892\/20\/NL\/FF\/ab"],"award-info":[{"award-number":["4000129892\/20\/NL\/FF\/ab"]}],"id":[{"id":"10.13039\/501100000844","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Region of Crete","award":["-"],"award-info":[{"award-number":["-"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Water vapor is one of the essential variables in monitoring the Earth\u2019s climate. The Ocean and Land Color Instrument (OLCI) on-board the Copernicus Sentinel-3 missions measures the Integrated Water Vapor (IWV) column over land and ocean surfaces. Post-launch calibration and validation of satellite measurements constitutes a key process in the operational phase of Earth observation satellites. This work presents the external and independent validation of OLCI-A IWV product using the regional network of continuously operating Global Navigation Satellite System (GNSS) comprised 10 stations distributed over the island of Crete in the eastern Mediterranean. The Sentinel-3A\/-3B OLCI imagery that captures in a single scene the entire area of Crete has been examined. For each OLCI image, the IWV value of cloud-free pixels containing the GNSS stations have been derived and compared against simultaneous GNSS-derived measurements. The absolute as well as the relative bias between OLCI-A and OLCI-B IWV measurements have been determined. There is a good agreement between OLCI and GNSS with a bias of \u22120.57 mm \u00b1 2.90 mm for OLCI(A) and +2.42 \u00b1 3.41 mm for OLCI(B). The results of this regional validation activity are compared against other studies and the regular validation carried out at the Sentinel-3 Mission Performance Center. This work concludes that the accuracy of the OLCI IWV products is within its design requirements. The potential synergy between Sentinel-2 and Sentinel-3 IWV products is also discussed.<\/jats:p>","DOI":"10.3390\/rs12162606","type":"journal-article","created":{"date-parts":[[2020,8,13]],"date-time":"2020-08-13T02:58:02Z","timestamp":1597287482000},"page":"2606","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["Validation of Sentinel-3 OLCI Integrated Water Vapor Products Using Regional GNSS Measurements in Crete, Greece"],"prefix":"10.3390","volume":"12","author":[{"given":"Stelios","family":"Mertikas","sequence":"first","affiliation":[{"name":"Geodesy and Geomatics Engineering Laboratory, Technical University of Crete, GR-73100 Chania, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Panagiotis","family":"Partsinevelos","sequence":"additional","affiliation":[{"name":"SenseLab Research, Technical University of Crete, GR-73100 Chania, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Achilleas","family":"Tripolitsiotis","sequence":"additional","affiliation":[{"name":"Space Geomatica P.C., Xanthoudidou 10A, GR-73132 Chania, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Costas","family":"Kokolakis","sequence":"additional","affiliation":[{"name":"Space Geomatica P.C., Xanthoudidou 10A, GR-73132 Chania, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"George","family":"Petrakis","sequence":"additional","affiliation":[{"name":"SenseLab Research, Technical University of Crete, GR-73100 Chania, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xenophon","family":"Frantzis","sequence":"additional","affiliation":[{"name":"Geodesy and Geomatics Engineering Laboratory, Technical University of Crete, GR-73100 Chania, Greece"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,8,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1431","DOI":"10.1175\/BAMS-D-13-00047.1","article-title":"The concept of essential climate variables in support of climate research, applications, and policy","volume":"95","author":"Bojinski","year":"2014","journal-title":"Bull. 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