{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T14:55:39Z","timestamp":1782140139902,"version":"3.54.5"},"reference-count":25,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2023,10,18]],"date-time":"2023-10-18T00:00:00Z","timestamp":1697587200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"DSIT NMS"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>In recent years, the concept of a Fiducial Reference Measurement (FRM) has been developed to highlight the need for precise and well-characterised measurements tailored explicitly to the post-launch calibration and validation (Cal\/Val) of Earth observation satellite missions. The confidence that stems from robust, unambiguous uncertainty assessment of space observations is fundamental to assessing the changes in the Earth system and climate model prediction and delivering the essential evidence-based input for policy makers and society striving to mitigate and adapt to climate change. The underlying concept of an FRM has long been a core element of a Cal\/Val program, providing a \u2018trustable\u2019 reference against which performance can be anchored or assessed. The \u2018FRM\u2019 label was created to embody into such a reference a set of key criteria. These criteria included the establishment of documented evidence of uncertainty with respect to a community-agreed reference (ideally SI-traceable) and specific tailoring to the needs of a satellite mission. It therefore facilitates comparison and interoperability between products and missions in a cost-efficient manner. Committee on Earth Observation Satellites (CEOS) Working Group Cal\/Val (WGCV) is now putting in place a framework to assess the maturity and compliance of a \u2018Cal\/Val reference measurement\u2019 in terms of a set of community-agreed criteria which define it to be of CEOS-FRM quality. The assessment process is based on a maturity matrix that provides a visual assessment of the state of any FRM against each of a set of given criteria, making visible where it is mature and where evolution and effort are still needed. This paper provides the overarching definition of what constitutes an FRM and introduces the new CEOS-FRM assessment framework.<\/jats:p>","DOI":"10.3390\/rs15205017","type":"journal-article","created":{"date-parts":[[2023,10,19]],"date-time":"2023-10-19T02:54:43Z","timestamp":1697684083000},"page":"5017","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["Fiducial Reference Measurements (FRMs): What Are They?"],"prefix":"10.3390","volume":"15","author":[{"given":"Philippe","family":"Goryl","sequence":"first","affiliation":[{"name":"European Space Agency ESA\/ESRIN, 00044 Frascati, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nigel","family":"Fox","sequence":"additional","affiliation":[{"name":"Earth Observation, Climate and Optical Group, National Physical Laboratory, Teddington TW11 0LW, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Craig","family":"Donlon","sequence":"additional","affiliation":[{"name":"European Space Agency ESA\/ESTEC, 2201 Noordwijk, The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Paolo","family":"Castracane","sequence":"additional","affiliation":[{"name":"Rhea System S.p.A. for ESA\/ESRIN, 00044 Frascati, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,10,18]]},"reference":[{"key":"ref_1","unstructured":"(2023, October 16). CEOS Cal\/Val Portal. Available online: https:\/\/calvalportal.ceos.org\/."},{"key":"ref_2","unstructured":"(2023, October 16). Radiometric Calibration Network (RadCalNet) Portal. Available online: https:\/\/www.radcalnet.org\/."},{"key":"ref_3","unstructured":"(2023, October 16). Quality Assurance Framework for Earth Observation. Available online: https:\/\/qa4eo.org\/."},{"key":"ref_4","unstructured":"(2023, October 16). Quality Assurance Framework for Earth Observation\u2014QA4EO Tools. Available online: https:\/\/qa4eo.org\/tools.php."},{"key":"ref_5","unstructured":"(2023, October 16). The International System of Units (SI). Available online: https:\/\/www.bipm.org\/en\/measurement-units."},{"key":"ref_6","unstructured":"(2023, October 16). Mises-en-Pratique. Available online: https:\/\/www.bipm.org\/en\/publications\/mises-en-pratique."},{"key":"ref_7","unstructured":"(2023, October 16). The Earthnet Data Assessment Project (EDAP+). Available online: https:\/\/earth.esa.int\/eogateway\/activities\/edap."},{"key":"ref_8","unstructured":"Donlon, C., and Goryl, P. (2013, January 26\u201329). Fiducial Reference Measurements (FRM) for Sentinel-3. Proceedings of the Sentinel-3 Validation Team (S3VT) Meeting, ESA\/ESRIN, Frascati, Italy."},{"key":"ref_9","unstructured":"(2023, October 16). The Copernicus In-Situ Component. Available online: https:\/\/insitu.copernicus.eu\/."},{"key":"ref_10","unstructured":"Boesch, H., Brindley, H., Carminati, F., Fox, N., Helder, D., Hewison, T., Houtz, D., Hunt, S., Kopp, G., and Mlynczak, M. (2019). SI-Traceable Space-Based Climate Observation System: A CEOS and GSICS Workshop, National Physical Laboratory, London, UK, 9\u201311 September 2019, NPL."},{"key":"ref_11","unstructured":"BIPM (2017). International Vocabulary of Metrology, BIPM. [3rd ed.]. Available online: https:\/\/www.bipm.org."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/S0034-4257(98)00031-5","article-title":"AERONET\u2014A federated instrument network and data archive for aerosol characterization","volume":"66","author":"Holben","year":"1998","journal-title":"Remote Sens. Environ."},{"key":"ref_13","unstructured":"(2023, October 16). Amazon Rain Forest Site for SAR Calibration. Available online: https:\/\/calvalportal.ceos.org\/web\/guest\/amazon-rain-forest-sites."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"591","DOI":"10.6028\/jres.100.044","article-title":"A Third Generation Water Bath Blackbody Source","volume":"5","author":"Fowler","year":"1995","journal-title":"J. Res. Natl. Inst. Stand. Technol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"258","DOI":"10.1175\/1520-0426(2004)021<0258:TMIRCA>2.0.CO;2","article-title":"The Miami, 2001 Infrared Radiometer Calibration and Intercomparison: 1. Laboratory Characterization of Blackbody Targets","volume":"21","author":"Rice","year":"2004","journal-title":"J. Atmos. Ocean. Technol."},{"key":"ref_16","unstructured":"Theocharous, E., and Fox, N.P. (2023, October 16). CEOS Comparison of IR Brightness Temperature Measurements in Support of Satellite Validation. Part II: Laboratory Comparison of the Brightness Temperature of Blackbodies. Available online: https:\/\/eprintspublications.npl.co.uk\/4759\/1\/OP4.pdf."},{"key":"ref_17","unstructured":"(2023, October 16). Fiducial Reference Measurements for Satellite Temperature Product Validation. Available online: https:\/\/www.frm4sts.org\/."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Zibordi, G., Donlon, C., and Albert, P. (2014). Optical Radiometry for Ocean Climate Measurements, Elsevier. [1st ed.].","DOI":"10.1016\/B978-0-12-417011-7.00009-X"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Bouvet, M., Thome, K., Berthelot, B., Bialek, A., Czapla-Myers, J., Fox, N.P., Goryl, P., Henry, P., Ma, L., and Marcq, S. (2019). RadCalNet: A Radiometric Calibration Network for Earth Observing Imagers Operating in the Visible to Shortwave Infrared Spectral Range. Remote Sens., 11.","DOI":"10.3390\/rs11202401"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Goyens, C., De Vis, P., and Hunt, S. (2021, January 11\u201316). Automated Generation of Hyperspectral Fiducial Reference Measurements of Water and Land Surface Reflectance for the Hypernets Networks. Proceedings of the 2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, Belgium, Brussels.","DOI":"10.1109\/IGARSS47720.2021.9553738"},{"key":"ref_21","unstructured":"(2023, October 16). Lunar Calibration Algorithm Working Area. Available online: http:\/\/gsics.atmos.umd.edu\/bin\/view\/Development\/LunarWorkArea."},{"key":"ref_22","unstructured":"(2023, October 16). Lunar Irradiance Model ESA: LIME. Available online: https:\/\/calvalportal.ceos.org\/lime."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Fox, N., and Green, P. (2020). Traceable Radiometry Underpinning Terrestrial- and Helio-Studies (TRUTHS): An Element of a Space-Based Climate and Calibration Observatory. Remote Sens., 12.","DOI":"10.3390\/rs12152400"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1519","DOI":"10.1175\/BAMS-D-12-00149.1","article-title":"Achieving climate change absolute accuracy in orbit","volume":"Volume 94","author":"Wielicki","year":"2013","journal-title":"BAMS (Bulletin of the American Meteorological Society)"},{"key":"ref_25","unstructured":"(2023, October 16). The 2022 GCOS Implementation Plan (GCOS-244). Available online: https:\/\/library.wmo.int\/index.php?lvl=notice_display&id=22134."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/15\/20\/5017\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T21:09:21Z","timestamp":1760130561000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/15\/20\/5017"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,10,18]]},"references-count":25,"journal-issue":{"issue":"20","published-online":{"date-parts":[[2023,10]]}},"alternative-id":["rs15205017"],"URL":"https:\/\/doi.org\/10.3390\/rs15205017","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,10,18]]}}}