{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T16:20:59Z","timestamp":1787070059721,"version":"3.56.0"},"reference-count":52,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2020,11,6]],"date-time":"2020-11-06T00:00:00Z","timestamp":1604620800000},"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>Phytoplankton is at the base of the marine food web and plays a fundamental role in the global carbon cycle. Ongoing climate change significantly impacts phytoplankton distribution in the ocean. Monitoring phytoplankton is crucial for a full understanding of changes in the marine ecosystem. To observe phytoplankton from space, chlorophyll-a concentration (Chl) has been widely used as a proxy of algal biomass, although it can be impacted by physiology. Therefore, there has been an increasing focus towards estimating phytoplankton biomass in units of carbon (Cphyto). Here, we developed an algorithm to quantify Cphyto from space-based observations that accounts for the spatio-temporal variations of the backscattering coefficient associated with the fraction of detrital particles that do not covary with Chl. The main findings are: (i) a spatial and temporal variation of the detritus component must be accounted for in the Cphyto algorithm; (ii) the refined Cphyto algorithm performs better (relative bias of 23.7%) than any previously existing model; and (iii) our algorithm shows the lowest error in Cphyto across areas where picophytoplankton dominates (relative bias of 14%). In other areas, it is currently not possible to accurately assess the performance of the refined algorithm due to the paucity of in situ carbon data associated with nano- and micro-phytoplankton size classes.<\/jats:p>","DOI":"10.3390\/rs12213640","type":"journal-article","created":{"date-parts":[[2020,11,6]],"date-time":"2020-11-06T09:03:04Z","timestamp":1604653384000},"page":"3640","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":24,"title":["Improving the Retrieval of Carbon-Based Phytoplankton Biomass from Satellite Ocean Colour Observations"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0477-173X","authenticated-orcid":false,"given":"Marco","family":"Bellacicco","sequence":"first","affiliation":[{"name":"Climate Modelling Laboratory, Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Via E. Fermi 45, 00044 Frascati, Italy"},{"name":"Consiglio Nazionale delle Ricerche (CNR), Istituto di Scienze Marine (ISMAR), Via Fosso del Cavaliere, 100 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0239-0033","authenticated-orcid":false,"given":"Jaime","family":"Pitarch","sequence":"additional","affiliation":[{"name":"Consiglio Nazionale delle Ricerche (CNR), Istituto di Scienze Marine (ISMAR), Via Fosso del Cavaliere, 100 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8191-8179","authenticated-orcid":false,"given":"Emanuele","family":"Organelli","sequence":"additional","affiliation":[{"name":"Consiglio Nazionale delle Ricerche (CNR), Istituto di Scienze Marine (ISMAR), Via Fosso del Cavaliere, 100 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3492-583X","authenticated-orcid":false,"given":"Victor","family":"Martinez-Vicente","sequence":"additional","affiliation":[{"name":"Plymouth Marine Laboratory (PML), Prospect Place, The Hoe, Plymouth PL1 3DH, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gianluca","family":"Volpe","sequence":"additional","affiliation":[{"name":"Consiglio Nazionale delle Ricerche (CNR), Istituto di Scienze Marine (ISMAR), Via Fosso del Cavaliere, 100 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4203-0956","authenticated-orcid":false,"given":"Salvatore","family":"Marullo","sequence":"additional","affiliation":[{"name":"Climate Modelling Laboratory, Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Via E. Fermi 45, 00044 Frascati, Italy"},{"name":"Consiglio Nazionale delle Ricerche (CNR), Istituto di Scienze Marine (ISMAR), Via Fosso del Cavaliere, 100 Rome, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,11,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"181","DOI":"10.1002\/2013GB004743","article-title":"Global assessment of ocean carbon export by combining satellite observations and food-web models","volume":"28","author":"Siegel","year":"2014","journal-title":"Glob. Biogeochem. Cycles"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"591","DOI":"10.1038\/nature09268","article-title":"Global phytoplankton decline over the past century","volume":"466","author":"Boyce","year":"2010","journal-title":"Nature"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"578","DOI":"10.1038\/s41467-019-08457-x","article-title":"Ocean colour signature of climate change","volume":"10","author":"Dutkiewicz","year":"2019","journal-title":"Nat. Commun."},{"key":"ref_4","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_5","doi-asserted-by":"crossref","first-page":"457","DOI":"10.4319\/lo.1980.25.3.0457","article-title":"Nutrient- and light-limited growth of Thalassiosira fluviatilis in continuous culture, with implications for phytoplankton growth in the ocean1","volume":"25","author":"Laws","year":"1980","journal-title":"Limnol. Oceanogr."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"167","DOI":"10.1146\/annurev-marine-052913-021325","article-title":"Resurrecting the Ecological Underpinnings of Ocean Plankton Blooms","volume":"6","author":"Behrenfeld","year":"2014","journal-title":"Annu. Rev. Mar. Sci."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Behrenfeld, M.J., Boss, E., Siegel, D.A., and Shea, D.M. (2005). Carbon-based ocean productivity and phytoplankton physiology from space. Glob. Biogeochem. Cycles, 19.","DOI":"10.1029\/2004GB002299"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Westberry, T., Behrenfeld, M.J., Siegel, D.A., and Boss, E. (2008). Carbon-based primary productivity modeling with vertically resolved photoacclimation. Glob. Biogeochem. Cycles, 22.","DOI":"10.1029\/2007GB003078"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"2687","DOI":"10.1098\/rstb.2008.0019","article-title":"Evolved physiological responses of phytoplankton to their integrated growth environment","volume":"363","author":"Behrenfeld","year":"2008","journal-title":"Philos. Trans. R. Soc. B Biol. Sci."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Zhai, L., Platt, T., Tang, C., Dowd, M., Sathyendranath, S., and Forget, M.-H. (2008). Estimation of phytoplankton loss rate by remote sensing. Geophys. Res. Lett., 35.","DOI":"10.1029\/2008GL035666"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"36","DOI":"10.1016\/j.jmarsys.2009.09.005","article-title":"Seasonal and geographic variations in phytoplankton losses from the mixed layer on the Northwest Atlantic Shelf","volume":"80","author":"Zhai","year":"2010","journal-title":"J. Mar. Syst."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"4447","DOI":"10.5194\/bg-12-4447-2015","article-title":"Capturing optically important constituents and properties in a marine biogeochemical and ecosystem model","volume":"12","author":"Dutkiewicz","year":"2015","journal-title":"Biogeosciences"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"13844","DOI":"10.1038\/s41598-018-32047-4","article-title":"Summertime Primary and Secondary Contributions to Southern Ocean Cloud Condensation Nuclei","volume":"8","author":"Fossum","year":"2018","journal-title":"Sci. Rep."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Mart\u00ednez-Vicente, V., Evers-King, H., Roy, S., Kostadinov, T.S., Tarran, G.A., Graff, J.R., Brewin, R.J.W., Dall\u2019Olmo, G., Jackson, T., and Hickman, A.E. (2017). Intercomparison of Ocean Color Algorithms for Picophytoplankton Carbon in the Ocean. Front. Mar. Sci., 4.","DOI":"10.3389\/fmars.2017.00378"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1154","DOI":"10.1002\/grl.50252","article-title":"Optical backscattering is correlated with phytoplankton carbon across the Atlantic Ocean","volume":"40","author":"Tarran","year":"2013","journal-title":"Geophys. Res. Lett."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1016\/j.dsr.2015.04.006","article-title":"Analytical phytoplankton carbon measurements spanning diverse ecosystems","volume":"102","author":"Graff","year":"2015","journal-title":"Deep Sea Res. Part I Oceanogr. Res. Pap."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"73","DOI":"10.3354\/meps07998","article-title":"Carbon-to-chlorophyll ratio and growth rate of phytoplankton in the sea","volume":"383","author":"Sathyendranath","year":"2009","journal-title":"Mar. Ecol. Prog. Ser."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Mara\u00f1\u00f3n, E., Cerme\u00f1o, P., Huete-Ortega, M., L\u00f3pez-Sandoval, D.C., Mouri\u00f1o-Carballido, B., and Rodr\u00edguez-Ramos, T. (2014). Resource Supply Overrides Temperature as a Controlling Factor of Marine Phytoplankton Growth. PLoS ONE, 9.","DOI":"10.1371\/journal.pone.0099312"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Kostadinov, T.S., Siegel, D.A., and Maritorena, S. (2009). Retrieval of the particle size distribution from satellite ocean color observations. J. Geophys. Res. Ocean., 114.","DOI":"10.1029\/2009JC005303"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"561","DOI":"10.5194\/os-12-561-2016","article-title":"Carbon-based phytoplankton size classes retrieved via ocean color estimates of the particle size distribution","volume":"12","author":"Kostadinov","year":"2016","journal-title":"Ocean Sci."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"177","DOI":"10.1016\/j.rse.2017.02.015","article-title":"Size-partitioned phytoplankton carbon and carbon-to-chlorophyll ratio from ocean colour by an absorption-based bio-optical algorithm","volume":"194","author":"Roy","year":"2017","journal-title":"Remote Sens. Environ."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"27","DOI":"10.1016\/j.pocean.2004.07.001","article-title":"The role of seawater constituents in light backscattering in the ocean","volume":"61","author":"Stramski","year":"2004","journal-title":"Prog. Oceanogr."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"5439","DOI":"10.1038\/s41467-018-07814-6","article-title":"The open-ocean missing backscattering is in the structural complexity of particles","volume":"9","author":"Organelli","year":"2018","journal-title":"Nat. Commun."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"e2020GL087100","DOI":"10.1029\/2020GL087100","article-title":"Experimental Estimates of Optical Backscattering Associated with Submicron Particles in Clear Oceanic Waters","volume":"47","author":"Zhang","year":"2020","journal-title":"Geophys. Res. Lett."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"9767","DOI":"10.1029\/2019GL084078","article-title":"Global Variability of Optical Backscattering by Non-algal particles From a Biogeochemical-Argo Data Set","volume":"46","author":"Bellacicco","year":"2019","journal-title":"Geophys. Res. Lett."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"17632","DOI":"10.1364\/OE.20.017632","article-title":"Particle backscattering as a function of chlorophyll and phytoplankton size structure in the open-ocean","volume":"20","author":"Brewin","year":"2012","journal-title":"Opt. Express"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"595","DOI":"10.1016\/j.rse.2016.08.004","article-title":"Influence of photoacclimation on the phytoplankton seasonal cycle in the Mediterranean Sea as seen by satellite","volume":"184","author":"Bellacicco","year":"2016","journal-title":"Remote Sens. Environ."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"7672","DOI":"10.1029\/2018GL078185","article-title":"Global Distribution of Non-algal Particles from Ocean Color Data and Implications for Phytoplankton Biomass Detection","volume":"45","author":"Bellacicco","year":"2018","journal-title":"Geophys. Res. Lett."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"18607","DOI":"10.1029\/96JC03243","article-title":"Inherent optical property inversion of ocean color spectra and its biogeochemical interpretation: 1. Time series from the Sargasso Sea","volume":"102","author":"Garver","year":"1997","journal-title":"J. Geophys. Res. Ocean."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"947","DOI":"10.5194\/bg-6-947-2009","article-title":"Significant contribution of large particles to optical backscattering in the open ocean","volume":"6","author":"Westberry","year":"2009","journal-title":"Biogeosciences"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"21532","DOI":"10.1364\/OE.20.021532","article-title":"Particulate optical scattering coefficients along an Atlantic Meridional Transect","volume":"20","author":"Boss","year":"2012","journal-title":"Opt. Express"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"152","DOI":"10.1016\/j.rse.2017.03.036","article-title":"An improved optical classification scheme for the Ocean Colour Essential Climate Variable and its applications","volume":"203","author":"Jackson","year":"2017","journal-title":"Remote Sens. Environ."},{"key":"ref_33","unstructured":"Jackson, T., Chuprin, A., Sathyendranath, S., Grant, M., Z\u00fchlke, M., Dingle, J., Storm, T., Boettcher, M., and Fomferra, N. (2019, December 22). Ocean Colour Climate Change Initiative (OC_CCI)\u2014Interim Phase. Product User Guide. D3.4 PUG. Available online: https:\/\/esa-oceancolour-cci.org\/sites\/esa-oceancolour-cci.org\/alfresco.php?file=a68aa514-3668-4935-9235-fca10f7e8bee&name=OC-CCI-PUG-v4.1-v1.pdf."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"5755","DOI":"10.1364\/AO.41.005755","article-title":"Deriving inherent optical properties from water color: A multiband quasi-analytical algorithm for optically deep waters","volume":"41","author":"Lee","year":"2002","journal-title":"Appl. Opt."},{"key":"ref_35","unstructured":"Lee, Z. (2019, December 22). Update of the Quasi-Analytical Algorithm (QAA_v6). Available online: http:\/\/www.ioccg.org\/groups\/Software_OCA\/QAA_v6_2014209.pdf."},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Pitarch, J., Bellacicco, M., Organelli, E., Volpe, G., Colella, S., Vellucci, V., and Marullo, S. (2020). Retrieval of Particulate Backscattering Using Field and Satellite Radiometry: Assessment of the QAA Algorithm. Remote Sens., 12.","DOI":"10.3390\/rs12010077"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"271","DOI":"10.1016\/j.rse.2013.09.016","article-title":"The Ocean Colour Climate Change Initiative: III. A round-robin comparison on in-water bio-optical algorithms","volume":"162","author":"Brewin","year":"2015","journal-title":"Remote Sens. Environ."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"540","DOI":"10.1016\/j.rse.2005.06.002","article-title":"Assessment of apparent and inherent optical properties derived from SeaWiFS with field data","volume":"97","author":"Berthon","year":"2005","journal-title":"Remote Sens. Environ."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"432","DOI":"10.1109\/LGRS.2011.2170659","article-title":"Uncertainties in Remote Sensing Reflectance from MODIS-Terra","volume":"9","author":"Melin","year":"2012","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_40","doi-asserted-by":"crossref","unstructured":"Sathyendranath, S., Brewin, R.J.W., Brockmann, C., Brotas, V., Calton, B., Chuprin, A., Cipollini, P., Couto, A.B., Dingle, J., and Doerffer, R. (2019). An Ocean-Colour Time Series for Use in Climate Studies: The Experience of the Ocean-Colour Climate Change Initiative (OC-CCI). Sensors, 19.","DOI":"10.3390\/s19194285"},{"key":"ref_41","unstructured":"Press, W.H., Teukolsky, S.A., Vetterling, W.T., and Flannery, B.P. (1988). Numerical Recipes in C, Cambridge University Press."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1071","DOI":"10.1029\/2018GB006125","article-title":"Effects of Eddy-Driven Subduction on Ocean Biological Carbon Pump","volume":"33","author":"Resplandy","year":"2019","journal-title":"Glob. Biogeochem. Cycles"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"5552","DOI":"10.1364\/AO.52.005552","article-title":"Influence of Raman scattering on ocean color inversion models","volume":"52","author":"Westberry","year":"2013","journal-title":"Appl. Opt."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1791","DOI":"10.1002\/2016GB005458","article-title":"Modeled Chl:C ratio and derived estimates of phytoplankton carbon biomass and its contribution to total particulate organic carbon in the global surface ocean","volume":"30","author":"Arteaga","year":"2016","journal-title":"Glob. Biogeochem. Cycles"},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Siegel, D.A., Maritorena, S., Nelson, N.B., and Behrenfeld, M.J. (2005). Independence and interdependencies among global ocean color properties: Reassessing the bio-optical assumption. J. Geophys. Res. Ocean., 110.","DOI":"10.1029\/2004JC002527"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"15419","DOI":"10.1364\/OE.18.015419","article-title":"Coherence of particulate beam attenuation and backscattering coefficients in diverse open ocean environments","volume":"18","author":"Westberry","year":"2010","journal-title":"Opt. Express"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1002\/2015GB005276","article-title":"Annual cycles of phytoplankton biomass in the subarctic Atlantic and Pacific Ocean","volume":"30","author":"Westberry","year":"2016","journal-title":"Glob. Biogeochem. Cycles"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1146\/annurev-marine-121916-063319","article-title":"The Ecology, Biogeochemistry, and Optical Properties of Coccolithophores","volume":"10","author":"Balch","year":"2018","journal-title":"Annu. Rev. Mar. Sci."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"1229","DOI":"10.1002\/2017JC013030","article-title":"Assessing the Variability in the Relationship between the Particulate Backscattering Coefficient and the Chlorophyll a Concentration from a Global Biogeochemical-Argo Database","volume":"123","author":"Barbieux","year":"2018","journal-title":"J. Geophys. Res. Ocean."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"1530","DOI":"10.1016\/j.dsr2.2006.05.005","article-title":"Prokaryoplankton standing stocks in oligotrophic gyre and equatorial provinces of the Atlantic Ocean: Evaluation of inter-annual variability","volume":"53","author":"Heywood","year":"2006","journal-title":"Deep Sea Res. Part II: Top. Stud. Oceanogr."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"837","DOI":"10.5194\/bg-4-837-2007","article-title":"Contribution of picoplankton to the total particulate organic carbon concentration in the eastern South Pacific","volume":"4","author":"Grob","year":"2007","journal-title":"Biogeosciences"},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"34147","DOI":"10.1364\/OE.408439","article-title":"Drivers of spectral optical scattering by particles in the upper 500 m of the Atlantic Ocean","volume":"28","author":"Organelli","year":"2020","journal-title":"Opt. Express"}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/12\/21\/3640\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T10:30:06Z","timestamp":1760178606000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/12\/21\/3640"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,11,6]]},"references-count":52,"journal-issue":{"issue":"21","published-online":{"date-parts":[[2020,11]]}},"alternative-id":["rs12213640"],"URL":"https:\/\/doi.org\/10.3390\/rs12213640","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,11,6]]}}}