The Use of Sentinel-3 Imagery to Monitor Cyanobacterial Blooms

Cyanobacterial harmful algal blooms (CHABs) have been a concern for aquatic systems, especially those used for water supply and recreation. Thus, the monitoring of CHABs is essential for the establishment of water governance policies. Recently, remote sensing has been used as a tool to monitor CHABs worldwide. Remote monitoring of CHABs relies on the optical properties of pigments, especially the phycocyanin (PC) and chlorophyll-a (chl-a). The goal of this study is to evaluate the potential of recent launch the Ocean and Land Color Instrument (OLCI) on-board the Sentinel-3 satellite to identify PC and chl-a. To do this, OLCI images were collected over the Western part of Lake Erie (U.S.A.) during the summer of 2016, 2017, and 2018. When comparing the use of traditional remote sensing algorithms to estimate PC and chl-a, none was able to accurately estimate both pigments. However, when single and band ratios were used to estimate these pigments, stronger correlations were found. These results indicate that spectral band selection should be re-evaluated for the development of new algorithms for OLCI images. Overall, Sentinel 3/OLCI has the potential to be used to identify PC and chl-a. However, algorithm development is needed

Technical note: Algal Pigment Index 2 in the Atlantic off the southwest Iberian Peninsula: standard and regional algorithms

In this study, Algal Pigment Index 2 (API2) is investigated in Sagres, an area located in the Atlantic off the southwestern Iberian Peninsula. Standard results provided by the MEdium Resolution Image Spectrometer (MERIS) ocean colour sensor were compared with alternative data products, determined through a regional inversion scheme, using both MERIS and in situ remote sensing reflectances (R-rs) as input data. The reference quantity for performance assessment is in situ total chlorophyll a (TChl a) concentration estimated through a phytoplankton absorption coefficient (i.e. equivalent to API2). Additional comparison of data products has also been addressed for TChl a concentration determined by high-performance liquid chromatography. The MERIS matchup analysis revealed a systematic underestimation of TChl a, which was confirmed with an independent comparison of product map analysis. The study demonstrates the importance of regional algorithms for the study area that could complement upcoming standard results of the current Sentinel-3/OLCI space mission

Underway spectrophotometry in the Fram Strait (European Arctic Ocean): a highly resolved chlorophyll a data source for complementing satellite ocean color

Satellite remote sensing of chlorophyll a concentration (Chl-a) in the Arctic Ocean is spatially and temporally limited and needs to be supplemented and validated with substantial volumes of in situ observations. Here, we evaluated the capability of obtaining highly resolved in situ surface Chl-a using underway spectrophotometry operated during two summer cruises in 2015 and 2016 in the Fram Strait. Results showed that Chl-a measured using high pressure liquid chromatography (HPLC) was well related (R2 = 0.90) to the collocated particulate absorption line height at 676 nm obtained from the underway spectrophotometry system. This enabled continuous surface Chl-a estimation along the cruise tracks. When used to validate Chl-a operational products as well as to assess the Chl-a algorithms of the aqua moderate resolution imaging spectroradiometer (MODIS-A) and Sentinel-3 Ocean Land Color Imager (OLCI) Level 2 Chl-a operational products, and from OLCI Level 2 products processed with Polymer atmospheric correction algorithm (version 4.1), the underway spectrophotometry based Chl-a data sets proved to be a much more sufficient data source by generating over one order of magnitude more match-ups than those obtained from discrete water samples. Overall, the band ratio (OCI, OC4) Chl-a operational products from MODIS-A and OLCI as well as OLCI C2RCC products showed acceptable results. The OLCI Polymer standard output provided the most reliable Chl-a estimates, and nearly as good results were obtained from the OCI algorithm with Polymer atmospheric correction method. This work confirms the great advantage of the underway spectrophotometry in enlarging in situ Chl-a data sets for the Fram Strait and improving satellite Chl-a validation and Chl-a algorithm assessment over discrete water sample analysis in the laboratory

Selection of the key earth observation sensors and platforms focusing on applications for Polar Regions in the scope of Copernicus system 2020-2030

An optimal payload selection conducted in the frame of the H2020 ONION project (id 687490) is presented based on the ability to cover the observation needs of the Copernicus system in the time period 2020–2030. Payload selection is constrained by the variables that can be measured, the power consumption, and weight of the instrument, and the required accuracy and spatial resolution (horizontal or vertical). It involved 20 measurements with observation gaps according to the user requirements that were detected in the top 10 use cases in the scope of Copernicus space infrastructure, 9 potential applied technologies, and 39 available commercial platforms. Additional Earth Observation (EO) infrastructures are proposed to reduce measurements gaps, based on a weighting system that assigned high relevance for measurements associated to Marine for Weather Forecast over Polar Regions. This study concludes with a rank and mapping of the potential technologies and the suitable commercial platforms to cover most of the requirements of the top ten use cases, analyzing the Marine for Weather Forecast, Sea Ice Monitoring, Fishing Pressure, and Agriculture and Forestry: Hydric stress as the priority use cases.Peer ReviewedPostprint (published version

Benefits and lessons learned from the Sentinel-3 tandem phase

During its commissioning phase, the Copernicus Sentinel-3B satellite has been placed in a tandem formation with Sentinel-3A for a period of 6 months. This configuration allowed a direct comparison of measurements obtained by the two satellites. The purpose of this paper was to present the range of analyses that can be performed from this dataset, highlighting methodology aspects and the main outcomes for each instrument. We examined, in turn, the benefit of the tandem in understanding instrument operational modes differences, in assessing inter-satellite differences, and in validating measurement uncertainties. The results highlighted the very good consistency of the Sentinel-3A and B instruments, ensuring the complete inter-operability of the constellation. Tandem comparisons also pave the way for further improvements through harmonization of the sensors (OLCI), correction of internal stray-light sources (SLSTR), or high-frequency processing of SRAL SARM data. This paper provided a comprehensive overview of the main results obtained, as well as insights into some of the results. Finally, we drew the main lessons learned from the Sentinel-3 tandem phase and provided recommendations for future missions

Global retrieval of phytoplankton functional types based on empirical orthogonal functions using CMEMS GlobColour merged products and further extension to OLCI data

This study presents an algorithm for globally retrieving chlorophyll a (Chl-a) concentrations of phytoplankton functional types (PFTs) from multi-sensor merged ocean color (OC) products or Sentinel-3A (S3) Ocean and Land Color Instrument (OLCI) data from the GlobColour archive in the frame of the Copernicus Marine Environmental Monitoring Service (CMEMS). The retrieved PFTs include diatoms, haptophytes, dinoflagellates, green algae and prokaryotic phytoplankton. A previously proposed method to retrieve various phytoplankton pigments, based on empirical orthogonal functions (EOF), is investigated and adapted to retrieve Chl-a concentrations of multiple PFTs using extensive global data sets of in situ pigment measurements and matchups with satellite OC products. The performance of the EOF-based approach is assessed and cross-validated statistically. The retrieved PFTs are compared with those derived from diagnostic pigment analysis (DPA) based on in situ pigment measurements. Results show that the approach predicts well Chl-a concentrations of most of the mentioned PFTs. The performance of the approach is, however, less accurate for prokaryotes, possibly due to their general low variability and small concentration range resulting in a weak signal which is extracted from the reflectance data and corresponding EOF modes. As a demonstration of the approach utilization, the EOF-based fitted models based on satellite reflectance products at nine bands are applied to the monthly GlobColour merged products. Climatological characteristics of the PFTs are also evaluated based on ten years of merged products (2002−2012) through inter-comparisons with other existing satellite derived products on phytoplankton composition including phytoplankton size class (PSC), SynSenPFT, OC-PFT and PHYSAT. Inter-comparisons indicate that most PFTs retrieved by our study agree well with previous corresponding PFT/PSC products, except that prokaryotes show higher Chl-a concentration in low latitudes. PFT dominance derived from our products is in general well consistent with the PHYSAT product. A preliminary experiment of the retrieval algorithm using eleven OLCI bands is applied to monthly OLCI products, showing comparable PFT distributions with those from the merged products, though the matchup data for OLCI are limited both in number and coverage. This study is to ultimately deliver satellite global PFT products for long-term continuous observation, which will be updated timely with upcoming OC data, for a comprehensive understanding of the variability of phytoplankton composition structure at a global or regional scale

Validation of Copernicus Sentinel-3/OLCI Level 2 Land Integrated Water Vapour product

Validation of the Integrated Water Vapour (IWV) from Sentinel-3 Ocean and Land Colour Instrument (OLCI) was performed as a part of the “ESA/Copernicus Space Component Validation for Land Surface Temperature, Aerosol Optical Depth and Water Vapour Sentinel-3 Products” (LAW) project. High-spatial-resolution IWV observations in the near-infrared spectral region from the OLCI instruments aboard the Sentinel-3A and Sentinel-3B satellites provide continuity with observations from MERIS (Medium Resolution Imaging Spectrometer). The IWV was compared with reference observations from two networks: GNSS (Global Navigation Satellite System) precipitable water vapour from the SuomiNet network and integrated lower tropospheric columns from radio-soundings from the IGRA (Integrated Radiosonde Archive) database. Results for cloud-free matchups over land show a wet bias of 7 %–10 % for OLCI, with a high correlation against the reference observations (0.98 against SuomiNet and 0.90 against IGRA). Both OLCI-A and OLCI-B instruments show almost identical results, apart from an anomaly observed in camera 3 of the OLCI-B instrument, where observed biases are lower than in other cameras in either instrument. The wavelength drift in sensors was investigated, and biases in different cameras were found to be independent of wavelength. Effect of cloud proximity was found to have almost no effect on observed biases, indicating that cloud flagging in the OLCI IWV product is sufficiently reliable. We performed validation of random uncertainty estimates and found them to be consistent with the statistical a posteriori estimates, but somewhat higher

Complementary tools for aquaculture management: remote sensing and in situ approaches for Sines

Tese de mestrado, Ciências do Mar, Universidade de Lisboa, Faculdade de Ciências, 2020O estado crítico dos recursos marinhos tem vindo a impulsionar o rápido desenvolvimento da aquacultura. De facto, a nível mundial, a produção aquícola regista atualmente um crescimento mais rápido que qualquer outro setor da indústria alimentar. No entanto, o aumento de práticas intensivas de aquacultura tem gerado preocupações, principalmente devido aos potenciais impactos ambientais associados. A presente dissertação teve como foco uma produção intensiva de robalo (Dicentrarchus labrax, L. 1758) localizada no sudoeste da Costa Ibérica (Sines, Portugal). Na área de produção, a qualidade da água e os possíveis impactos da atividade no meio envolvente foram avaliados. Para tal, seis campanhas de amostragem, realizadas entre junho de 2018 e julho de 2019, foram realizadas para recolha de dados de parâmetros físicos, químicos e biológicos ao longo das jaulas onde se encontram os peixes. Foram analisados dados de temperatura, salinidade, parâmetros de claridade da água, matéria particulada em suspensão, oxigénio dissolvido, pH, nutrientes e biomassa e composição fitoplanctónica. Parte dos dados foram adquiridos a partir de sondas multiparamétricas (e.g. temperatura, salinidade, oxigénio dissolvido e pH); as concentrações de matéria particulada em suspensão, nutrientes e biomassa fitoplanctónica foram determinadas analiticamente em laboratório. Os parâmetros de claridade da água foram obtidos através de dados de radiometria e da profundidade de Secchi. Os resultados dos parâmetros de qualidade da água foram comparados com as gamas consideradas como aceitáveis e ótimas para a aquacultura de peixes em ambientes marinhos, de acordo com a literatura internacional. Atualmente, a literatura científica disponível ainda fornece uma orientação direta limitada para a avaliação da qualidade da água nas águas costeiras portuguesas. Os resultados apresentaram valores dentro das gamas aceitáveis definidas na literatura (exceto um valor isolado de fosfatos obtido em outubro de 2018). Para avaliar o impacto desta produção de peixe no meio recetor, as médias e extremos dos parâmetros de qualidade da água passíveis de serem diretamente influenciados pela aquacultura foram comparados com os dados disponíveis para a região de Sines, anteriores ao início da produção de robalo na região. Neste caso, foram obtidas concentrações mais elevadas de azoto inorgânico dissolvido em comparação com os valores de referência para Sines. No geral, a claridade da água, oxigénio dissolvido, nutrientes e biomassa fitoplanctónica não sugeriram impactos negativos das unidades de produção na qualidade da água local. Não obstante, são necessárias mais análises para diferenciar os potenciais impactos da elevada industrialização em Sines, dos impactos da aquacultura. Os resultados do presente trabalho apontam como causas para o baixo stress ambiental diversos fatores: o regime hidrodinâmico, o baixo tempo de residência da água no sistema, a estratégia de alimentação e a dimensão das unidades de produção. As campanhas de amostragem in situ permitiram ainda verificar uma grande variabilidade dos parâmetros analisados na região, e a necessidade de utilizar métodos complementares para uma melhor caracterização espácio-temporal da área envolvente. Os produtos de deteção remota (DR) disponibilizam dados com grande resolução espácio-temporal, que podem complementar as abordagens amostragens in situ fornecendo informações relevantes os end users, neste caso, o aquacultor. Dados climatológicos da temperatura da água e da concentração de clorofila-a (indicador de biomassa fitoplanctônica) com os respetivos parâmetros estatísticos (desvio padrão e percentis 10 e 90) foram determinados para a região envolvente da aquacultura. Para verificar a coerência dos mesmos para a região, estes foram comparados com os dados in situ recolhidos durante as campanhas de amostragem. As médias semanais do percentil 90 (p90) da temperatura da superfície do mar (TSM) provaram ser adequados para alertar condições anómalas no local da aquacultura. Por outro lado, devido à alta variabilidade sazonal e interanual de clorofila-a (Chl-a) na região, a média do p90 mostrou ser mais fidedigna para a deteção de condições de alerta. O cálculo de anomalias diárias em comparação com dias anteriores (7 e 14 dias) também forneceu informações relevantes sobre a ocorrência de blooms na região. Atualmente, a disponibilização de dados de satélite quase em tempo real em várias bases de dados públicas, possibilita facultar ferramentas valiosas de baixo custo ao aquacultor. Para além da região envolvente, a área onde se encontram instaladas as jaulas de peixe foi também caracterizada utilizando dados de DR (TSM, Chl-a e turbidez) e comparada com os dados obtidos in situ. Para fins de monitorização, medições discretas de temperatura e turbidez indicam ser suficientes para representar a área devido à baixa variabilidade espacial. A alta variabilidade de Chl-a na região revelam a necessidade de recolher dados em várias estações ao longo da produção, ou complementar dados in situ mais escassos com produtos de DR de maior resolução. A adequabilidade de diversos produtos de DR considerados ao longo desta tese foi preliminarmente avaliada para a área da aquacultura em Sines. Para analisar a Chl-a, os novos sensores de alta resolução espacial da Agência Espacial Europeia, desenvolvidos no âmbito do Programa Copernicus da Comissão Europeia, como o Ocean and Land Color Instrument (OLCI) e o Multispectral Instrument (MSI) a bordo dos satélites Sentinel-3 e Sentinel-2, mostrou contribuições importantes para as áreas adjacentes ao litoral. Missões com dados históricos de Chl-a, como o Medium Resolution Imaging Spectrometer (MERIS) a bordo do Envisat e o produto que engloba múltiplos sensores da Ocean Colour Climate Change Initiative (OC-CCI), possibilitam uma melhor compreensão de variações intra-anuais. O produto de TSM do Group of High Resolution Sea Surface Temperature (GHRSST) revelou captar consistentemente o sinal de temperatura em Sines. Dada a intensa industrialização da zona de Sines e, neste caso, a presença de uma descarga de água quente proveniente da central termoelétrica de Sines a sul da produção, o uso deste último produto requer atenção na interpretação dos dados. Tal facto destaca a necessidade de aquisição de conhecimentos sólidos sobre a região de estudo para posteriores aplicações de produtos de DR, de modo a minimizar possíveis erros nas análises. Por fim, é salientada a necessidade da utilização de produtos de alta resolução espacial e temporal para monitorar as áreas costeiras, bem como a complementaridade da deteção remota com a recolha de dados in situ.The critical status of marine resources has provided impetus for rapid growth in aquaculture, which has become the fastest growing sector of the food industry worldwide. However, the increase of intensive aquaculture practices has been raising global concern mostly due to the associated potential environmental impacts. The present dissertation focused on an intense aquaculture in the SW Iberian Coast (Sines, Portugal) dedicated to the production of European sea bass (Dicentrarchus labrax, L. 1758). Water quality and potential impacts were assessed in the production area. Physical, chemical and biological parameters were collected along the cages in the course of six field campaigns, carried out between June 2018 and July 2019. These were temperature, salinity, water clarity parameters, suspended particulate matter, dissolved oxygen, pH, nutrients, and phytoplankton biomass and composition. The obtained water quality parameters were compared with threshold values for marine fish production, according to international literature. The scientific literature currently provides limited direct guidance for water quality assessment in Portuguese coastal waters. Results showed values within the acceptable for marine fish production (except an isolated value of phosphates obtained in October 2018). To assess the impact of this fish production in the receiving medium, the averages and extremes of water quality parameters that might be directly influenced by aquaculture were further compared with available data for Sines region, previous to the sea bass production in the area. A higher dissolved inorganic nitrogen signal was found in the collected data, compared to background nutrient levels for Sines. Overall, water clarity, dissolved oxygen, nutrients and phytoplankton biomass did not suggest any detrimental impacts of the production units on local water quality, although more research is needed. The findings point to the hydrodynamic regime, low water residence time in the system, feeding strategy and the dimension of production units as the reason for the lack of stress on the receiving waters. Typically, coastal aquaculture faces with high water quality variability. Given the capabilities of satellite remote sensing (RS) products to provide high spatio-temporal data, they have the potential to be used as complementary tools to support the activity, providing important knowledge for end users. Climatological water temperature and phytoplankton biomass (indexed as chlorophyll-a concentration) data with respective statistics were provided for the aquaculture region and compared with the in situ data collected to verify consistency. Sea surface temperature (SST) weekly 90th percentiles (p90) proved to be suitable to alert anomalous conditions in the aquaculture site. On the other hand, due to high chlorophyll-a (Chl-a) seasonal and interannual variability in the region, the mean p90 proved to be more reliable for the detection of alert conditions. The computation of daily anomalies compared to previous days (7-days and 14-days) also provided valuable information on the occurrence of blooms in the region. Currently, near real time satellite data can be accessed freely, providing users with valuable tools in a cost-effect way. The aquaculture site was also characterized using RS retrieved variables (SST, Chl-a and turbidity) and compared with the ground truth. For monitoring purposes, single discrete measures of SST and turbidity were found to be most likely sufficient to represent the area due to low spatial variability. High Chl-a variability in the region emphasized the need to collect several datapoints along the production or to complement scarcer in situ data with higher resolution RS products. In this thesis, several remote sensing products were considered, and their suitability for the aquaculture area in Sines was preliminarily assessed. To study the variability of Chl-a, novel high spatiotemporal resolution RS sensors, such as the Ocean and Land Colour Instrument on Sentinel-3 (OLCIS3) and the Multispectral Instrument on Sentinel-2 (MSI-S2), showed important contributions when focusing areas adjacent to the coast. Missions with available historical Chl-a data such as the Medium Resolution Imaging Spectrometer on-board Envisat, and the multi-sensor product from Ocean Colour Climate Change Initiative (OC-CCI), further enable understanding interannual features. The SST product from the Group of High Resolution Sea Surface Temperature (GHRSST) revealed to consistently capture the temperature signal in Sines area. For the aquaculture surroundings, given the high industrialization of the region and, in this case, the presence of a hot water discharge from a thermoelectric powerplant south of the production, the use of this product requires caution to not misinterpret data contamination. This highlights the need to have knowledge of the study region in order to minimize possible error inducers in analyzes with satellite products. The necessity of high spatial and temporal resolution products to monitor coastal areas is therefore underlined, as well as the complementarity of remote sensing and in situ approaches

Optiliste veetüüpide põhine lähenemine sise- ja rannikuvee veekvaliteedi hindamiseks

Väitekirja elektrooniline versioon ei sisalda publikatsiooneInimestele on meeldinud ajast aega elada seal, kus maa ja vesi kohtuvad. Mistõttu on järvede, jõgede ja rannikualade lähedal inimtegevuse mõju suurenenud, mis omakorda põhjustab veekogude seisundi muutumist ning loob vajaduse veekogude operatiivseks seireks. Enamasti põhinevad veekogude seireprogrammid veekogudes teostatud punktmõõtmistel. See meetod aga ei suuda kajastada kogu veekogu kiiresti muutuvaid omadusi ja reaalset seisundit. Seetõttu on oluline lisaks punktmõõtmistele rakendada veekeskkonna operatiivse jälgimise meetodeid, millest kaugseire on üks võimsamaid. Kaugseire pakub tõhusaid viise veekvaliteedi ruumiliste ja ajaliste erinevuste jälgimiseks. Euroopa Liidu ja Euroopa Kosmoseagentuuri Copernicus programmi raames loodud Sentinel-2 ja Sentinel-3 seeria satelliitide hea ruumilise, ajalise ja spektraalse lahutusega andmete tasuta kättesaadavus on loonud reaalse võimaluse sise- ja rannikuvete seires operatiivselt kasutada täiendavalt satelliitandmeid. Need andmed võimaldavad jälgida kogu veekogu ajalist ja ruumilist muutlikkust ning seirata ka raskesti ligipääsetavaid veekogusid. Sise- ja rannikuveed on optiliselt keerukad, sest vee optilised omadused on mõjutatud sõltumatult erinevate optiliselt aktiivsete ainete poolt. Seetõttu standardsed kaugseire algoritmid veekvaliteedi hindamiseks neis veekogudes tihti ei tööta. Doktoritöö tulemusena tutvustati optiliste veetüüpide põhist lähenemist sise- ja rannikuvete veekvaliteedi parameetrite hindamiseks kaugseireandmete põhjal. Eelnimetatud meetod võtab arvesse vee optilisi omadusi ega piiritle ennast konkreetse veekoguga, seetõttu on tulemused rakendatavad kõigil sarnaste optiliste omadustega veekogudel üle maailma.Humans have long enjoyed living where land and water meet. At the same time, the impact of human activities close to lakes, rivers, and coastal areas has increased, which has caused the deterioration of water bodies. Therefore, the state of a water body requires constant monitoring to assess the magnitude of the impact of human activity and to respond when needed. Traditional water monitoring programs are mainly based on in situ measurements; however, considering that water bodies are dynamic in nature, this method may not reflect the status of the whole water body. Therefore, in addition to traditional monitoring, it is important to implement methods that allow more operative monitoring of the aquatic environment. Remote sensing offers effective ways to observe spatial and temporal variations in water quality. The free availability of data with high spatial, temporal and spectral resolution from the Sentinel-2 and Sentinel-3 family satellites launched under the European Union and the European Space Agency Copernicus programme has created a real opportunity for satellite data being used operationally for additional water quality monitoring for inland and coastal waters. Such waters are optically complex, as they are independently influenced by different optically significant constituents. Therefore, standard remote sensing algorithms to estimate water quality often fail in these waters. As a result of the thesis, an optical water type guided approach to estimate water quality in inland and coastal waters using remote sensing data was presented. The method considers the optical properties of water but does not limit itself to a particular water body. So, results are applicable to all the water bodies with similar optical properties of water.https://www.ester.ee/record=b534022

System Vicarious Calibration for Copernicus Ocean Colour Missions: Updated Requirements and Recommendations for a European Site

The Copernicus Program has been established through the Regulation EU No377/2014 with the objective to ensure long-term and sustained provision of accurate and reliable data on environment and security through dedicated services. Among these, the Copernicus Marine Environment Monitoring Service and the marine component of the Climate Change Service, both rely on satellite ocean colour observations to deliver data on water quality and climate relevant quantities such as chlorophyll-a concentration used as a proxy for phytoplankton biomass. Satellite ocean colour missions require in situ highly accurate radiometric measurements for the indirect calibration (so called System Vicarious Calibration (SVC)) of the space sensor. This process is essential to minimize the combined effects of uncertainties affecting the space sensor calibration and those resulting from the inaccuracy of processing algorithms and models applied for the generation of data products. SVC is thus a fundamental element to maximize the return on investments for the Copernicus Program by delivering to the user science community satellite ocean colour data with accuracy granting achievement of target objectives from applications addressing environmental and climate change issues. The long-term Copernicus Program foresees multiple ocean colour missions (i.e., the Sentinel-3 satellites carrying the Ocean and Land Colour Instrument (OLCI)). The need to ensure the highest accuracy to satellite derived data products contributing to the construction of Climate Data Records (CDRs), suggests the realization, deployment and sustain of a European in situ infrastructure supporting SVC for Sentinel-3 missions, fully independent from similar facilities established and maintained by other space agencies (e.g., that operated in the Pacific Ocean by US agencies). It is emphasized that the need to cope with long-term Copernicus objectives on data accuracy, implies very stringent requirements for the in situ infrastructure and location providing reference measurements for SVC. These requirements, in fact, are much higher than those imposed by SVC for a single mission. The content of this Report, which is a revised version of a previous one (Zibordi et al. 2017), builds on the long-standing experience of the JRC on ocean colour radiometry. This experience counts on decadal field and laboratory measurements performed in support of validation and SVC applications, and additionally on activities comprehensively embracing measurement protocols, instruments characterization and the initiation of autonomous measurement infrastructures. Overall, this Report summarizes a number of recent investigations led by the JRC on SVC requirements for the creation of CDRs. The final objective is to consolidate in a single document the elements essential fJRC.D.2-Water and Marine Resource