{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,24]],"date-time":"2026-04-24T14:15:13Z","timestamp":1777040113015,"version":"3.51.4"},"reference-count":40,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2019,5,8]],"date-time":"2019-05-08T00:00:00Z","timestamp":1557273600000},"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":["4000117454\/16\/I-Sbo"],"award-info":[{"award-number":["4000117454\/16\/I-Sbo"]}],"id":[{"id":"10.13039\/501100000844","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>An intercomparison of radiance and irradiance ocean color radiometers (The Second Laboratory Comparison Exercise\u2014LCE-2) was organized within the frame of the European Space Agency funded project Fiducial Reference Measurements for Satellite Ocean Color (FRM4SOC) May 8\u201313, 2017 at Tartu Observatory, Estonia. LCE-2 consisted of three sub-tasks: 1) SI-traceable radiometric calibration of all the participating radiance and irradiance radiometers at the Tartu Observatory just before the comparisons; 2) Indoor intercomparison using stable radiance and irradiance sources in controlled environment; and 3) Outdoor intercomparison of natural radiation sources over terrestrial water surface. The aim of the experiment was to provide one link in the chain of traceability from field measurements of water reflectance to the uniform SI-traceable calibration, and after calibration to verify whether different instruments measuring the same object provide results consistent within the expected uncertainty limits. This paper describes the activities and results of the first two phases of LCE-2: the SI-traceable radiometric calibration and indoor intercomparison, the results of outdoor experiment are presented in a related paper of the same journal issue. The indoor experiment of the LCE-2 has proven that uniform calibration just before the use of radiometers is highly effective. Distinct radiometers from different manufacturers operated by different scientists can yield quite close radiance and irradiance results (standard deviation s &lt; 1%) under defined conditions. This holds when measuring stable lamp-based targets under stationary laboratory conditions with all the radiometers uniformly calibrated against the same standards just prior to the experiment. In addition, some unification of measurement and data processing must be settled. Uncertainty of radiance and irradiance measurement under these conditions largely consists of the sensor\u2019s calibration uncertainty and of the spread of results obtained by individual sensors measuring the same object.<\/jats:p>","DOI":"10.3390\/rs11091101","type":"journal-article","created":{"date-parts":[[2019,5,9]],"date-time":"2019-05-09T08:19:59Z","timestamp":1557389999000},"page":"1101","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":21,"title":["Laboratory Intercomparison of Radiometers Used for Satellite Validation in the 400\u2013900 nm Range"],"prefix":"10.3390","volume":"11","author":[{"given":"Viktor","family":"Vabson","sequence":"first","affiliation":[{"name":"Tartu Observatory, University of Tartu, 61602 T\u00f5ravere, Estonia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7565-1244","authenticated-orcid":false,"given":"Joel","family":"Kuusk","sequence":"additional","affiliation":[{"name":"Tartu Observatory, University of Tartu, 61602 T\u00f5ravere, Estonia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ilmar","family":"Ansko","sequence":"additional","affiliation":[{"name":"Tartu Observatory, University of Tartu, 61602 T\u00f5ravere, Estonia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3740-0772","authenticated-orcid":false,"given":"Riho","family":"Vendt","sequence":"additional","affiliation":[{"name":"Tartu Observatory, University of Tartu, 61602 T\u00f5ravere, Estonia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Krista","family":"Alikas","sequence":"additional","affiliation":[{"name":"Tartu Observatory, University of Tartu, 61602 T\u00f5ravere, Estonia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kevin","family":"Ruddick","sequence":"additional","affiliation":[{"name":"Royal Belgian Institute of Natural Sciences, 1000 Brussels, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6699-0962","authenticated-orcid":false,"given":"Ave","family":"Ansper","sequence":"additional","affiliation":[{"name":"Tartu Observatory, University of Tartu, 61602 T\u00f5ravere, Estonia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7185-8464","authenticated-orcid":false,"given":"Mariano","family":"Bresciani","sequence":"additional","affiliation":[{"name":"National Research Council of Italy, 21020 Ispra, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5327-6914","authenticated-orcid":false,"given":"Henning","family":"Burmester","sequence":"additional","affiliation":[{"name":"Helmholtz-Zentrum Geesthacht, Institute for Coastal Research, 21502 Geesthacht, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Maycira","family":"Costa","sequence":"additional","affiliation":[{"name":"University of Victoria, Victoria, BC V8P 5C2, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Davide","family":"D\u2019Alimonte","sequence":"additional","affiliation":[{"name":"Center for Marine and Environmental Research, University of Algarve, 8005-139 Faro, Portugal"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Giorgio","family":"Dall\u2019Olmo","sequence":"additional","affiliation":[{"name":"Plymouth Marine Laboratory, Plymouth PL1 3DH, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4671-6998","authenticated-orcid":false,"given":"Bahaiddin","family":"Damiri","sequence":"additional","affiliation":[{"name":"Cimel Electronique S.A.S, 75011 Paris, France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tilman","family":"Dinter","sequence":"additional","affiliation":[{"name":"Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, D-27570 Bremerhaven, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3937-4988","authenticated-orcid":false,"given":"Claudia","family":"Giardino","sequence":"additional","affiliation":[{"name":"National Research Council of Italy, 21020 Ispra, Italy"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kersti","family":"Kangro","sequence":"additional","affiliation":[{"name":"Tartu Observatory, University of Tartu, 61602 T\u00f5ravere, Estonia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Martin","family":"Ligi","sequence":"additional","affiliation":[{"name":"Tartu Observatory, University of Tartu, 61602 T\u00f5ravere, Estonia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Birgot","family":"Paavel","sequence":"additional","affiliation":[{"name":"Estonian marine institute, University of Tartu, 12618 Tallinn, Estonia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gavin","family":"Tilstone","sequence":"additional","affiliation":[{"name":"Plymouth Marine Laboratory, Plymouth PL1 3DH, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ronnie","family":"Van Dommelen","sequence":"additional","affiliation":[{"name":"Satlantic; Sea Bird Scientific, Bellevue, WA 98005, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sonja","family":"Wiegmann","sequence":"additional","affiliation":[{"name":"Alfred Wegener Institute Helmholtz Centre for 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