{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,24]],"date-time":"2026-03-24T06:08:41Z","timestamp":1774332521384,"version":"3.50.1"},"reference-count":38,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2018,1,26]],"date-time":"2018-01-26T00:00:00Z","timestamp":1516924800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Seventh Framework Programme","award":["FP7-ENV-308469"],"award-info":[{"award-number":["FP7-ENV-308469"]}]},{"DOI":"10.13039\/501100000943","name":"Commonwealth Scientific and Industrial Research Organisation","doi-asserted-by":"publisher","award":["Travel Grant"],"award-info":[{"award-number":["Travel Grant"]}],"id":[{"id":"10.13039\/501100000943","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>In the European Citclops project, with a prime aim of developing new tools to involve citizens in the water quality monitoring of natural waters, colour was identified as a simple property that can be measured via a smartphone app and by dedicated low-cost instruments. In a recent paper, we demonstrated that colour, as expressed mainly by the hue angle (\u03b1), can also be derived accurately and consistently from the ocean colour satellite instruments that have observed the Earth since 1997. These instruments provide superior temporal coverage of natural waters, albeit at a reduced spatial resolution of 300 m at best. In this paper, the list of algorithms is extended to the very first ocean colour instrument, and the Moderate Resolution Imaging Spectroradiometer (MODIS) 500-m resolution product. In addition, we explore the potential of the hue angle derivation from multispectral imaging instruments with a higher spatial resolution but reduced spectral resolution: the European Space Agency (ESA) multispectral imager (MSI) on Sentinel-2 A,B, the Operational Land Imager (OLI) on the National Aeronautics and Space Administration (NASA) Landsat-8, and its precursor, the Enhanced Thematic Mapper Plus (ETM+) on Landsat-7. These medium-resolution imagers might play a role in an upscaling from point measurements to the typical 1-km pixel size from ocean colour instruments. As the parameter \u03b1 (the colour hue angle) is fairly new to the community of water remote sensing scientists, we present examples of how colour can help in the image analysis in terms of water-quality products.<\/jats:p>","DOI":"10.3390\/rs10020180","type":"journal-article","created":{"date-parts":[[2018,1,26]],"date-time":"2018-01-26T11:29:02Z","timestamp":1516966142000},"page":"180","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":103,"title":["Hue-Angle Product for Low to Medium Spatial Resolution Optical Satellite Sensors"],"prefix":"10.3390","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8901-7567","authenticated-orcid":false,"given":"Hendrik","family":"Van der Woerd","sequence":"first","affiliation":[{"name":"Institute for Environmental Studies (IVM), Water & Climate Risk, VU University Amsterdam, De Boelelaan 1087, Amsterdam 1081HV, The Netherlands"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1331-9569","authenticated-orcid":false,"given":"Marcel","family":"Wernand","sequence":"additional","affiliation":[{"name":"Royal Netherlands Institute for Sea Research, Coastal Systems, Marine Optics & Remote Sensing, P.O. Box 59, Den Burg 1790AB, Texel, The Netherlands"}]}],"member":"1968","published-online":{"date-parts":[[2018,1,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"25663","DOI":"10.3390\/s151025663","article-title":"True colour classification of natural waters with medium-spectral resolution satellites: SeaWiFS, MODIS, MERIS and OLCI","volume":"15","author":"Wernand","year":"2015","journal-title":"Sensors"},{"key":"ref_2","unstructured":"(1932). Commission Internationale de l\u2019\u00c9clairage Proceedings, 1931, Cambridge University Press."},{"key":"ref_3","unstructured":"Wyszecki, G., and Stiles, W.S. (1982). Color Science: Concepts and Methods, Quantitative Data and Formulae, John Wiley & Sons."},{"key":"ref_4","unstructured":"(2017, July 29). Citclops (Citizens\u2019 Observatory for Coast and Ocean Optical Monitoring). Available online: www.citclops.eu."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Busch, J.A., Badaj\u00ed, R., Ceccaroni, L., Friedrichs, A., Piera, J., Simon, C., Thijsse, P., Wernand, M., Van der Woerd, H.J., and Zielinski, O. (2016). Citizen bio-optical observations from coast- and ocean and their compatibility with ocean colour satellite measurements. Remote Sens., 8.","DOI":"10.3390\/rs8110879"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"291","DOI":"10.1890\/110236","article-title":"The current state of citizen science as a tool for ecological research and public engagement","volume":"10","author":"Dickinson","year":"2012","journal-title":"Front. Ecol. Environ."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"128","DOI":"10.1016\/j.biocon.2013.05.025","article-title":"Realising the full potential of citizen science monitoring programs","volume":"165","author":"Tulloch","year":"2013","journal-title":"Biol. Conserv."},{"key":"ref_8","first-page":"257","article-title":"Citizen Scientists and Marine Research: Volunteer participants, their contributions and projection for the future","volume":"52","author":"Thiel","year":"2014","journal-title":"Oceanogr. Mar. Biol. Annu. Rev."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Wernand, M.R., Van der Woerd, H.J., and Gieskes, W.W.C. (2013). Trends in ocean colour and chlorophyll concentration from 1889 to present. PLoS ONE.","DOI":"10.1371\/journal.pone.0063766"},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Novoa, S., Wernand, M.R., and Van der Woerd, H.J. (2013). The Forel-Ule scale revisited spectrally: Preparation protocols, transmission measurements and chromaticity. J. Eur. Opt. Soc. Rapid Publ., 8.","DOI":"10.2971\/jeos.2013.13057"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Novoa, S., Wernand, M.R., and Van der Woerd, H.J. (2014). The Modern Forel-Ule scale: A \u2018Do-it-yourself\u2019 colour comparator for water monitoring. J. Eur. Opt. Soc. Rapid Publ., 9.","DOI":"10.2971\/jeos.2014.14025"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"3828","DOI":"10.1002\/2016JC012610","article-title":"Fjord light regime: Bio-optical variability, absorption budget, and hyperspectral light availability in Sognefjord and Trondheimsfjord, Norway","volume":"122","author":"Mascarenhas","year":"2017","journal-title":"J. Geophys. Res."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"697","DOI":"10.1002\/lom3.10059","article-title":"WACODI: A generic algorithm to derive the intrinsic color of natural waters from digital images","volume":"13","author":"Novoa","year":"2015","journal-title":"Limnol. Oceanogr. Methods"},{"key":"ref_14","first-page":"40","article-title":"Citizens and satellites: Assessment of phytoplankton dynamics in a NW Mediterranean aquaculture zone","volume":"47","author":"Busch","year":"2016","journal-title":"Int. J. Appl. Earth Obs. Geoinf."},{"key":"ref_15","unstructured":"(2017, August 08). SNAP (Sentinels Application Platform). Available online: http:\/\/step.esa.int\/main\/download\/."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1016\/j.rse.2007.03.012","article-title":"Examining the consistency of products derived from various ocean color sensors in open ocean (Case 1) waters in the perspective of a multi-sensor approach","volume":"111","author":"Morel","year":"2007","journal-title":"Remote Sens. Environ."},{"key":"ref_17","unstructured":"Lee, Z.-P. (2006). Remote Sensing of Inherent Optical Properties: Fundamentals, Tests of Algorithms, and Applications, IOCCG. Reports of the International Ocean-Colour Coordinating Group, No. 5."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"907","DOI":"10.1109\/JSTARS.2014.2360564","article-title":"MODIS-based Radiometric color extraction and classification of inland water with the Forel-Ule scale: A case study of lake Taihu","volume":"8","author":"Wang","year":"2015","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"4086","DOI":"10.1016\/j.rse.2007.12.013","article-title":"A 20-year Landsat water clarity census of Minnesota\u2019s 10,000 lakes","volume":"112","author":"Olmanson","year":"2008","journal-title":"Remote Sens. Environ."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"334","DOI":"10.1016\/j.rse.2012.04.004","article-title":"The possibility of using the Landsat image archive for monitoring long time trends in coloured dissolved organic matter concentration in lake waters","volume":"123","author":"Kutser","year":"2012","journal-title":"Remote Sens. Environ."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1016\/j.rse.2014.01.009","article-title":"Turbid wakes associated with offshore wind turbines observed with Landsat 8","volume":"145","author":"Vanhellemont","year":"2014","journal-title":"Remote Sens. Environ."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"108","DOI":"10.1016\/j.rse.2016.04.011","article-title":"Landsat 8: Providing continuity and increased precision for measuring multi-decadal time series of total suspended matter","volume":"185","author":"Lymburner","year":"2016","journal-title":"Remote Sens. Environ."},{"key":"ref_23","unstructured":"Van der Woerd, H.J., Wernand, M., Peters, M., Bala, M., and Brochmann, C. (2016, January 23\u201328). True color analysis of natural waters with SeaWiFS, MODIS, MERIS and OLCI by SNAP. Proceedings of the Ocean Optics XXIII, Victoria, BC, Canada."},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Antoine, D., Morel, A., Gordon, H.R., Banzon, V.F., and Evans, R.H. (2005). Bridging ocean color observations of the 1980\u2019s and 2000\u2019s in search of long-term trends. J. Geophys. Res., 110.","DOI":"10.1029\/2004JC002620"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1016\/j.rse.2011.11.026","article-title":"Sentinel-2: ESA\u2019s optical high-resolution mission for GMES operational services","volume":"120","author":"Drusch","year":"2012","journal-title":"Remote Sens. Environ."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"272","DOI":"10.1016\/j.rse.2014.08.001","article-title":"On-orbit radiometric characterization of OLI (Landsat-8) for applications in aquatic remote sensing","volume":"154","author":"Pahlevan","year":"2014","journal-title":"Remote Sens. Environ."},{"key":"ref_27","unstructured":"(2017, July 29). Ocean Optics Book. Available online: www.oceanopticsbook.info\/view\/overview-of-optical-oceanography\/reflectances."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Mobley, C.D. (1995). Hydrolight 3.0 Users\u2019 Guide, SRI International.","DOI":"10.21236\/ADA306564"},{"key":"ref_29","unstructured":"(2015, August 10). IOCCG Data. Available online: http:\/\/www.ioccg.org\/groups\/OCAG_data.html."},{"key":"ref_30","unstructured":"Mueller, J.L., Fargion, G.S., Mcclain, C.R., Mueller, J.L., Morel, A., Frouin, R., Davis, C., Arnone, R., Carder, K., and Steword, R.G. (2003). NASA\/TM-2003-Ocean Optics Protocols for Satellite Ocean Color Sensor Validation, Revision 4, Volume III: Radiometric Measurements and Data Analysis Protocols."},{"key":"ref_31","unstructured":"(2017, October 20). Sentinel-2 SRF. Available online: https:\/\/earth.esa.int\/web\/sentinel\/user-guides\/sentinel-2-msi\/document-library\/."},{"key":"ref_32","unstructured":"(2017, October 30). USGS Spectral Viewer, Available online: https:\/\/landsat.usgs.gov\/using-usgs-spectral-viewer."},{"key":"ref_33","unstructured":"(2017, October 30). MODIS Relative Spectral Response, Available online: https:\/\/mcst.gsfc.nasa.gov\/calibration\/parameters."},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Maul, G.A. (1985). Introduction to Satellite Oceanography, Martinus Nijhof Publishers.","DOI":"10.1007\/978-94-009-5061-0"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1016\/j.marchem.2004.02.008","article-title":"Modeling the spectral shape of absorption by chromophoric dissolved organic matter","volume":"89","author":"Twardowski","year":"2004","journal-title":"Mar. Chem."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Lee, Z.P., Du, K.P., and Arnone, R. (2005). A model for the diffuse attenuation coefficient of downwelling irradiance. J. Geophys. Res., 110.","DOI":"10.1029\/2004JC002275"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"418","DOI":"10.1038\/nature20584","article-title":"High-resolution mapping of global surface water and its long-term changes","volume":"540","author":"Pekel","year":"2016","journal-title":"Nature"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"2303","DOI":"10.1080\/01431160500396865","article-title":"Monitoring the maximum turbidity zone and detecting fine-scale turbidity features in the Gironde estuary using high spatial resolution satellite sensor (SPOT HRV, Landsat ETM+) data","volume":"27","author":"Doxaran","year":"2006","journal-title":"Int. J. Remote Sens."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/2\/180\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T14:52:42Z","timestamp":1760194362000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/10\/2\/180"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2018,1,26]]},"references-count":38,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2018,2]]}},"alternative-id":["rs10020180"],"URL":"https:\/\/doi.org\/10.3390\/rs10020180","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2018,1,26]]}}}