{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T12:02:39Z","timestamp":1774526559723,"version":"3.50.1"},"reference-count":71,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2021,3,9]],"date-time":"2021-03-09T00:00:00Z","timestamp":1615248000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Monitoring water quality parameters and their ecological effects in transitional waters is usually performed through in situ sampling programs. These are expensive and time-consuming, and often do not represent the total area of interest. Remote sensing techniques offer enormous advantages by providing cost-effective systematic observations of a large water system. This study evaluates the potential of water quality monitoring using Sentinel-2 observations for the period 2018\u20132020 for the Sado estuary (Portugal), through an algorithm intercomparison exercise and time-series analysis of different water quality parameters (i.e., colored dissolved organic matter (CDOM), chlorophyll-a (Chl-a), suspended particulate matter (SPM), and turbidity). Results suggest that Sentinel-2 is useful for monitoring these parameters in a highly dynamic system, however, with challenges in retrieving accurate data for some of the variables, such as Chl-a. Spatio-temporal variability results were consistent with historical data, presenting the highest values of CDOM, Chl-a, SPM and turbidity during Spring and Summer. This work is the first study providing annual and seasonal coverage with high spatial resolution (10 m) for the Sado estuary, being a key contribution for the definition of effective monitoring programs. Moreover, the potential of remote sensing methodologies for continuous water quality monitoring in transitional systems under the scope of the European Water Framework Directive is briefly discussed.<\/jats:p>","DOI":"10.3390\/rs13051043","type":"journal-article","created":{"date-parts":[[2021,3,9]],"date-time":"2021-03-09T12:08:01Z","timestamp":1615291681000},"page":"1043","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":71,"title":["Deriving Water Quality Parameters Using Sentinel-2 Imagery: A Case Study in the Sado Estuary, Portugal"],"prefix":"10.3390","volume":"13","author":[{"given":"Giulia","family":"Sent","sequence":"first","affiliation":[{"name":"MARE\u2014Marine and Environmental Science Centre, Faculdade de Ci\u00eancias da Universidade de Lisboa, 1749-016 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7252-1241","authenticated-orcid":false,"given":"Beatriz","family":"Biguino","sequence":"additional","affiliation":[{"name":"MARE\u2014Marine and Environmental Science Centre, Faculdade de Ci\u00eancias da Universidade de Lisboa, 1749-016 Lisboa, Portugal"},{"name":"Instituto Hidrogr\u00e1fico, Rua das Trinas 49, 1249-093 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9797-0251","authenticated-orcid":false,"given":"Luciane","family":"Favareto","sequence":"additional","affiliation":[{"name":"MARE\u2014Marine and Environmental Science Centre, Faculdade de Ci\u00eancias da Universidade de Lisboa, 1749-016 Lisboa, Portugal"}]},{"given":"Joana","family":"Cruz","sequence":"additional","affiliation":[{"name":"MARE\u2014Marine and Environmental Science Centre, Faculdade de Ci\u00eancias da Universidade de Lisboa, 1749-016 Lisboa, Portugal"}]},{"given":"Carolina","family":"S\u00e1","sequence":"additional","affiliation":[{"name":"MARE\u2014Marine and Environmental Science Centre, Faculdade de Ci\u00eancias da Universidade de Lisboa, 1749-016 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8834-4374","authenticated-orcid":false,"given":"Ana In\u00e9s","family":"Dogliotti","sequence":"additional","affiliation":[{"name":"Instituto de Astronom\u00eda y F\u00edsica del Espacio (IAFE), CONICET-Universidad de Buenos Aires, Pabell\u00f3n IAFE, Ciudad Universitaria, Ciudad Aut\u00f3noma de Buenos Aires C1428EGA, Argentina"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5215-7120","authenticated-orcid":false,"given":"Carla","family":"Palma","sequence":"additional","affiliation":[{"name":"Instituto Hidrogr\u00e1fico, Rua das Trinas 49, 1249-093 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8612-4167","authenticated-orcid":false,"given":"Vanda","family":"Brotas","sequence":"additional","affiliation":[{"name":"MARE\u2014Marine and Environmental Science Centre, Faculdade de Ci\u00eancias da Universidade de Lisboa, 1749-016 Lisboa, Portugal"},{"name":"Departamento de Biologia Vegetal, Faculdade de Ci\u00eancias, Universidade de Lisboa, 1749-016 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6539-5830","authenticated-orcid":false,"given":"Ana C.","family":"Brito","sequence":"additional","affiliation":[{"name":"MARE\u2014Marine and Environmental Science Centre, Faculdade de Ci\u00eancias da Universidade de Lisboa, 1749-016 Lisboa, Portugal"},{"name":"Departamento de Biologia Vegetal, Faculdade de Ci\u00eancias, Universidade de Lisboa, 1749-016 Lisboa, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2021,3,9]]},"reference":[{"key":"ref_1","unstructured":"European Commission (2003). Common Implementation Strategy for the Water Framework Directive (2000\/60\/EC). Guidance Document No. 5. Transitional and Coastal Waters\u2014Typology, Reference Conditions and Classification Systems, European Commission."},{"key":"ref_2","unstructured":"IOCCG (2018). Reports and Monographs of the International Ocean Colour Coordinating Group Earth Observations in Support of Global Water Quality Monitoring, IOCCG. No. 17."},{"key":"ref_3","first-page":"483","article-title":"Chapter Nineteen: Human Impact And Management of Coastal And Estuarine Ecosystems, Estuar. Ecol","volume":"Volume 1","author":"Day","year":"2013","journal-title":"Human Impact and Management of Coastal and Estuarine Ecosystems"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1016\/j.marpolbul.2013.09.012","article-title":"Marine water quality monitoring: A review","volume":"77","author":"Karydis","year":"2013","journal-title":"Mar. Pollut. Bull."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Ansper, A., and Alikas, K. (2018). Retrieval of Chlorophyll a from Sentinel-2 MSI Data for the European Union Water Framework Directive Reporting Purposes. Remote Sens., 11.","DOI":"10.3390\/rs11010064"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"186","DOI":"10.1016\/j.pocean.2018.01.001","article-title":"An overview of approaches and challenges for retrieving marine inherent optical properties from ocean color remote sensing","volume":"160","author":"Werdell","year":"2018","journal-title":"Prog. Oceanogr."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Moses, W.J., Sterckx, S., Montes, M.J., De Keukelaere, L., and Knaeps, E. (2017). Atmospheric Correction for Inland Waters. Bio-optical Modeling and Remote Sensing of Inland Waters, Elsevier BV.","DOI":"10.1016\/B978-0-12-804644-9.00003-3"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Topp, S.N., Pavelsky, T.M., Jensen, D., Simard, M., and Ross, M.R.V. (2020). Research Trends in the Use of Remote Sensing for Inland Water Quality Science: Moving Towards Multidisciplinary Applications. Water, 12.","DOI":"10.3390\/w12010169"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"111604","DOI":"10.1016\/j.rse.2019.111604","article-title":"Seamless retrievals of chlorophyll-a from Sentinel-2 (MSI) and Sentinel-3 (OLCI) in inland and coastal waters: A machine-learning approach","volume":"240","author":"Pahlevan","year":"2020","journal-title":"Remote Sens. Environ."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"139612","DOI":"10.1016\/j.scitotenv.2020.139612","article-title":"COVID-19 lockdown measures reveal human impact on water transparency in the Venice Lagoon","volume":"736","author":"Braga","year":"2020","journal-title":"Sci. Total Environ."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1038\/s41598-020-65600-1","article-title":"New capabilities of Sentinel-2A\/B satellites combined with in situ data for monitoring small harmful algal blooms in complex coastal waters","volume":"10","author":"Caballero","year":"2020","journal-title":"Sci. Rep."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"3373","DOI":"10.1080\/01431161003747513","article-title":"Remote sensing of water quality parameters over Alqueva Reservoir in the south of Portugal","volume":"32","author":"Potes","year":"2011","journal-title":"Int. J. Remote Sens."},{"key":"ref_13","unstructured":"Sent, G., de Sa, C.V., and Dogliotti, A.I. (2020). Remote Sensing for Water Quality Studies: Test of Suspended Particulate Matter and Turbidity Algorithms for Portuguese Transitional and Inland Waters. [Master\u2019s Thesis, Universidade de Lisboa]."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Brito, A.C., Garrido-Amador, P., Gameiro, C., Nogueira, M., Moita, M.T., and Cabrita, M.T. (2020). Integrating in Situ and Ocean Color Data to Evaluate Ecological Quality under the Water Framework Directive. Water, 12.","DOI":"10.3390\/w12123443"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"169","DOI":"10.1016\/j.csr.2015.03.011","article-title":"Using remote sensing as a support to the implementation of the European Marine Strategy Framework Directive in SW Portugal","volume":"108","author":"Cristina","year":"2015","journal-title":"Cont. Shelf. Res."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"308","DOI":"10.1016\/j.rse.2017.10.022","article-title":"Sunglint correction of the Multi-Spectral Instrument (MSI)-SENTINEL-2 imagery over inland and sea waters from SWIR bands","volume":"204","author":"Harmel","year":"2018","journal-title":"Remote Sens. Environ."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1016\/j.rse.2019.04.021","article-title":"Chlorophyll algorithms for ocean color sensors\u2014OC4, OC5 & OC6","volume":"229","author":"Werdell","year":"2019","journal-title":"Remote Sens. Environ."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"401","DOI":"10.1007\/s10712-018-9476-0","article-title":"Imaging Spectrometry of Inland and Coastal Waters: State of the Art, Achievements and Perspectives","volume":"40","author":"Giardino","year":"2019","journal-title":"Surv. Geophys."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Neto, J., Ca\u00e7ador, I., Caetano, M., Cha\u00ednho, P., Costa, L., Gon\u00e7alves, A., Pereira, L., Pinto, L., Ramos, J., and Seixas, S. (2019). Cap\u00edtulo 16: Estu\u00e1rios. Rios de Portugal\u2014Comunidades, Processos e Altera\u00e7\u00f5es, Coimbra University Press.","DOI":"10.14195\/978-989-26-1624-7_16"},{"key":"ref_20","unstructured":"(2020, November 26). Reserva Natural do Estu\u00e1rio do Sado\u2014Informa\u00e7\u00e3o. Available online: http:\/\/www2.icnf.pt\/portal\/ap\/resource\/ap\/rnes\/rnes-net-%0Afinal.pdf."},{"key":"ref_21","unstructured":"Ferreira, J.G., Abreu, P.F., Bettencourt, A.M., Bricker, S.B., Marques, J.C., Meio, J.J., Newton, A., Norbe, A., Patricio, J., and Rocha, F. (2005). Water Framework Directive\u2014Transitional and Coastal Waters Proposal for the Definition of Water Bodies, MONAE."},{"key":"ref_22","unstructured":"Coutinho, M.T.C.P. (2003). Comunidade Fitoplanct\u00f3nica do Estu\u00e1rio do Sado. Estrutura, Din\u00e2mica e Aspectos Ecol\u00f3gicos, Instituo nacional de investiga\u00e7\u00e3o agr\u00e1ria e das pescas, IPIMAR."},{"key":"ref_23","unstructured":"Brito, P., Amorim, A., Andrade, C., Freitas, M.C., and Monteiro, J. (2003, January 12\u201319). Assessment of morphological change in estuarine systems\u2014A tool to evaluate responses to future sea level rise. The case of the Sado Estuary (Portugal). Proceedings of the II Congresso sobre Planejamento e Gest\u00e3o da Zonas Costeiras dos Pa\u00edses de Express\u00e3o Portuguesa, Recife, Brasil."},{"key":"ref_24","unstructured":"Sousa, F., and Louren\u00e7o, I. (1980). Oceanografia F\u00edsica do Estu\u00e1rio do Sad, Universidade de Lisboa."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Biguino, B., Sousa, F., and Brito, A.C. (2021). Variability of Currents and Water Column Structure in a Temperate Estuarine System (Sado Estuary, Portugal). Water, 13.","DOI":"10.3390\/w13020187"},{"key":"ref_26","unstructured":"Mitchell, B.G., Kahru, M., Wieland, J., and Stramska, M. (2002). Ocean Optics Protocols for Satellite Ocean Colour Sensor Validation, Revision 2, Determination of Spectral Absorption Coefficients of Particles, Dissolved Material and Phytoplankton for Discrete Water Samples."},{"key":"ref_27","unstructured":"UNESCO (1981). The practical salinity scale 1978 and the international equation of state seawater 1980. Tenth report of the joint panel on oceanographic tables and standards. UNESCO Tech. Pap. Mar. Sci., 36, 1\u201322."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"708","DOI":"10.1111\/j.0022-3646.1992.00708.x","article-title":"Separation of Chlorophylls c1c2, AND c3 of Marine Phytoplankton by Reversed-Phase-C18-High-Performance Liquid Chromatography1","volume":"28","author":"Kraay","year":"1992","journal-title":"J. Phycol."},{"key":"ref_29","first-page":"623","article-title":"Identification et quantification des pigments chlorophylliens et carotenoides des sediments marins: Un protocole d\u2019analyse par HPLC","volume":"19","author":"Brotas","year":"1996","journal-title":"Oceanol. Acta"},{"key":"ref_30","first-page":"182","article-title":"Protocol for determination of Total Suspended Matter in oceans and coastal zones","volume":"98","year":"1998","journal-title":"JCR Tech. Note"},{"key":"ref_31","unstructured":"Vanhellemont, Q., and Ruddick, K. (2016, January 23\u201328). ACOLITE processing for Sentinel-2 and Landsat-8: Atmospheric correction and aquatic applications. Proceedings of the Ocean Optics Conference 2016, Victoria, BC, Canada."},{"key":"ref_32","first-page":"9","article-title":"Evolution of the C2RCC neural network for Sentinel 2 and 3 for the retrieval of ocean colour products in normal and extreme optically complex waters","volume":"740","author":"Brockmann","year":"2016","journal-title":"Eur. Sp. Agency"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"9783","DOI":"10.1364\/OE.19.009783","article-title":"Atmospheric correction in presence of sun glint: Application to MERIS","volume":"19","author":"Steinmetz","year":"2011","journal-title":"Opt. Express"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1016\/j.rse.2019.03.010","article-title":"Adaptation of the dark spectrum fitting atmospheric correction for aquatic applications of the Landsat and Sentinel-2 archives","volume":"225","author":"Vanhellemont","year":"2019","journal-title":"Remote Sens. Environ."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"267","DOI":"10.1016\/j.rse.2019.03.018","article-title":"Assessment of atmospheric correction algorithms for the Sentinel-2A MultiSpectral Imager over coastal and inland waters","volume":"225","author":"Warren","year":"2019","journal-title":"Remote Sens. Environ."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"396","DOI":"10.1016\/j.ecss.2011.05.010","article-title":"An optical model for the remote sensing of coloured dissolved organic matter in coastal\/ocean waters","volume":"93","author":"Tiwari","year":"2011","journal-title":"Estuar. Coast. Shelf. Sci."},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Mannino, A., Russ, M.E., and Hooker, S.B. (2008). Algorithm development and validation for satellite-derived distributions of DOC and CDOM in the U.S. Middle Atlantic Bight. J. Geophys. Res. Space Phys., 113.","DOI":"10.1029\/2007JC004493"},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Chen, J., and Zhu, W. (2020). Consistency evaluation of landsat-7 and landsat-8 for improved monitoring of colored dissolved organic matter in complex water. Geocarto Int., 1\u201312.","DOI":"10.1080\/10106049.2020.1734872"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"036007","DOI":"10.1117\/1.JRS.11.036007","article-title":"Remote estimation of colored dissolved organic matter and chlorophyll-a in Lake Huron using Sentinel-2 measurements","volume":"11","author":"Chen","year":"2017","journal-title":"J. Appl. Remote Sens."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"535","DOI":"10.1016\/j.rse.2004.11.009","article-title":"Mapping lake CDOM by satellite remote sensing","volume":"94","author":"Kutser","year":"2005","journal-title":"Remote Sens. Environ."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"118","DOI":"10.1016\/j.rse.2012.01.024","article-title":"Operational MERIS-based NIR-red algorithms for estimating chlorophyll-a concentrations in coastal waters\u2014The Azov Sea case study","volume":"121","author":"Moses","year":"2012","journal-title":"Remote Sens. Environ."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1093\/plankt\/fbh151","article-title":"Effect of a waveband shift on chlorophyll retrieval from MERIS imagery of inland and coastal waters","volume":"27","author":"Gons","year":"2004","journal-title":"J. Plankton Res."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"854","DOI":"10.1016\/j.rse.2009.11.022","article-title":"Calibration and validation of a generic multisensor algorithm for mapping of total suspended matter in turbid waters","volume":"114","author":"Nechad","year":"2010","journal-title":"Remote. Sens. Environ."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"627","DOI":"10.1007\/s10872-011-0062-z","article-title":"Empirical ocean-color algorithms to retrieve chlorophyll-a, total suspended matter, and colored dissolved organic matter absorption coefficient in the Yellow and East China Seas","volume":"67","author":"Siswanto","year":"2011","journal-title":"J. Oceanogr."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"157","DOI":"10.1016\/j.rse.2014.09.020","article-title":"A single algorithm to retrieve turbidity from remotely-sensed data in all coastal and estuarine waters","volume":"156","author":"Dogliotti","year":"2015","journal-title":"Remote Sens. Environ."},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"Nechad, B., Ruddick, K., and Park, Y. (2009). Calibration and validation of a generic multisensor algorithm for mapping of turbidity in coastal waters. Remote Sens. Ocean Sea Ice Large Water Reg., 747.","DOI":"10.1117\/12.830700"},{"key":"ref_47","unstructured":"Campbell, J.B., and Wynne, R.H. (2011). Introduction to Remote Sensing, The Guilford Press. [5th ed.]."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1016\/j.pocean.2010.12.001","article-title":"Multi-sensor satellite time series of optical properties and chlorophyll-a concentration in the Adriatic Sea","volume":"91","author":"Vantrepotte","year":"2011","journal-title":"Prog. Oceanogr."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"7183","DOI":"10.1029\/2000JD900719","article-title":"Summarizing multiple aspects of model performance in a single diagram","volume":"106","author":"Taylor","year":"2001","journal-title":"J. Geophys. Res. Atmos."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"403","DOI":"10.1016\/j.rse.2015.07.018","article-title":"Validation of standard and alternative satellite ocean-color chlorophyll products off Western Iberia","volume":"168","author":"Brito","year":"2015","journal-title":"Remote Sens. Environ."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"64","DOI":"10.1016\/j.jmarsys.2008.05.014","article-title":"Summary diagrams for coupled hydrodynamic-ecosystem model skill assessment","volume":"76","author":"Jolliff","year":"2009","journal-title":"J. Mar. Syst."},{"key":"ref_52","unstructured":"IOCCG (2000). Reports of the International Ocean-Colour Coordinating Group. Remote Sensing of Ocean Colour in Coastal, and Other Optically-Complex, Waters, IOCCG."},{"key":"ref_53","doi-asserted-by":"crossref","unstructured":"Pereira-Sandoval, M., Ruescas, A., Urrego, P., Ruiz-Verd\u00fa, A., Delegido, J., Tenjo, C., Soria-Perpiny\u00e0, X., Vicente, E., Soria, J., and Moreno, J. (2019). Evaluation of Atmospheric Correction Algorithms over Spanish Inland Waters for Sentinel-2 Multi Spectral Imagery Data. Remote Sens., 11.","DOI":"10.3390\/rs11121469"},{"key":"ref_54","unstructured":"Steinmetz, P., Ramon, F., and Deschamps, D. (2016). Ocean Colour Climate Change (OC CCI)-Phase One, ESA."},{"key":"ref_55","unstructured":"Wang, M. (2014). Atmospheric correction of Ocean Color RS observations. IOCCG Summer Lecture Series, IOCCG."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"843","DOI":"10.4319\/lo.2003.48.2.0843","article-title":"Light scattering properties of marine particles in coastal and open ocean waters as related to the particle mass concentration","volume":"48","author":"Babin","year":"2003","journal-title":"Limnol. Oceanogr."},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"116","DOI":"10.1016\/j.rse.2011.11.013","article-title":"Review of constituent retrieval in optically deep and complex waters from satellite imagery","volume":"118","author":"Odermatt","year":"2012","journal-title":"Remote Sens. Environ."},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"119","DOI":"10.1016\/j.csr.2012.11.009","article-title":"Specific absorption coefficient of phytoplankton off the Southwest coast of the Iberian Peninsula: A contribution to algorithm development for ocean colour remote sensing","volume":"52","author":"Goela","year":"2013","journal-title":"Cont. Shelf. Res."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1016\/j.rse.2017.08.024","article-title":"Radiometric validation of atmospheric correction for MERIS in the Baltic Sea based on continuous observations from ships and AERONET-OC","volume":"200","author":"Qin","year":"2017","journal-title":"Remote Sens. Environ."},{"key":"ref_60","unstructured":"Simis, S., Stelzer, K., M\u00fcller, D., and Selmes, N. (2020, November 26). Copernicus Global Land Operations \u2018Cryosphere and Water\u2019. Available online: https:\/\/land.copernicus.eu\/global\/sites\/cgls.vito.be\/files\/products\/CGLOPS2_ATBD_LWQ300_1km_v1.3.1_I1.12.pdf."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"148","DOI":"10.1016\/j.ecss.2014.10.010","article-title":"Suspended matter concentrations in coastal waters: Methodological improvements to quantify individual measurement uncertainty","volume":"151","author":"Heymann","year":"2014","journal-title":"Estuarine Coast. Shelf Sci."},{"key":"ref_62","unstructured":"Mobley, C.D. (1994). Light and Water, Academic Press."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"233","DOI":"10.1016\/S0079-6611(98)00036-6","article-title":"Dispersal and deposition of suspended sediment on the shelf off the Tagus and Sado estuaries, S.W. Portugal","volume":"42","author":"Jouanneau","year":"1998","journal-title":"Prog. Oceanogr."},{"key":"ref_64","doi-asserted-by":"crossref","unstructured":"Santos, L., Pinto, A., Filipe, O., Cunha, \u00c2., Santos, E.B.H., and Almeida, A. (2016). Insights on the Optical Properties of Estuarine DOM\u2014Hydrological and Biological Influences. PLoS ONE, 11.","DOI":"10.1371\/journal.pone.0154519"},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"925","DOI":"10.5194\/bg-9-925-2012","article-title":"Tracing the transport of colored dissolved organic matter in water masses of the Southern Beaufort Sea: Relationship with hydrographic characteristics","volume":"9","author":"Matsuoka","year":"2012","journal-title":"Biogeosciences"},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1016\/j.ecolind.2011.07.025","article-title":"Defining phytoplankton class boundaries in Portuguese transitional waters: An evaluation of the ecological quality status according to the Water Framework Directive","volume":"19","author":"Brito","year":"2012","journal-title":"Ecol. Indic."},{"key":"ref_67","unstructured":"European Commision (2000). Directive 2000\/60\/EC of the European Parliament and of the Council of 23 October 2000 Establishing a Framework for Community Action in the Field of Water Policy, European Commission."},{"key":"ref_68","unstructured":"APA (2014). Plano de Gest\u00e3o de Regi\u00e3o Hidrogr\u00e1fica 2016\/2021\u2014Relat\u00f3rio de Caracteriza\u00e7\u00e3o\u2014Regi\u00e3o Hidrogr\u00e1fica do Sado e Mira (RH6), APA."},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.jmarsys.2007.07.001","article-title":"The relationship between CDOM and salinity in estuaries: An analytical and graphical solution","volume":"73","author":"Bowers","year":"2008","journal-title":"J. Mar. Syst."},{"key":"ref_70","doi-asserted-by":"crossref","first-page":"267","DOI":"10.1016\/j.envsci.2004.05.002","article-title":"The role of remote sensing technology in the EU water framework directive (WFD)","volume":"7","author":"Chen","year":"2004","journal-title":"Environ. Sci. Policy"},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"5347","DOI":"10.1080\/01431160500219406","article-title":"Remote sensing and GIS applications for estuarine ecosystem analysis: An overview","volume":"26","author":"Yang","year":"2005","journal-title":"Int. J. Remote Sens."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/5\/1043\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:35:45Z","timestamp":1760160945000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/13\/5\/1043"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,3,9]]},"references-count":71,"journal-issue":{"issue":"5","published-online":{"date-parts":[[2021,3]]}},"alternative-id":["rs13051043"],"URL":"https:\/\/doi.org\/10.3390\/rs13051043","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,3,9]]}}}