Consulta: subjectFacets:"Ocean colour"
Registros recuperados: 15
Data/hora: 06/06/2024 00:41:28

Which ocean colour algorithm for MERIS in North West European waters?
Provedor de dados: 5
Autores: Tilstone, Gavin; Mallor-hoya, Silvana; Gohin, Francis; Couto, Andre Belo; Sa, Carolina; Goela, Priscila; Cristina, Sonia; Airs, Ruth; Icely, John; Zuehlke, Marco; Groom, Steve.
Chlorophyll-a (Chl a) is a key parameter for the assessment of water quality in coastal and shelf environments. The availability of satellite ocean colour offers the potential of monitoring these regions at unprecedented spatial and temporal scales, as long as a high level of accuracy can be achieved. To use satellite derived Chl a to monitor these environments, it is imperative that rigorous accuracy assessments are undertaken to select the most accurate ocean colour algorithm(s).  To this end, the accuracy of a range of ocean colour Chl a algorithms for use with Medium Imaging Resolution Spectrometer (MERIS) Level 2 (L2) Remote Sensing Reflectance (Rrs), using two different atmospheric correction (AC) processors (COASTCOLOUR and MERIS Ground Segment...
Tipo: Text
Palavras-chave: Case 2 waters; Coastal waters; Shelf waters; Chlorophyll-a; North Sea; Ocean colour; Remote sensing; MERIS; English Channel; Mediterranean coast; Portuguese coast.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00359/46995/48634.pdf

Influence of Tropical Instability Waves on Phytoplankton Biomass near the Marquesas Islands
Provedor de dados: 5
Autores: Martinez, Elodie; Raapoto, Hirohiti; Maes, Christophe; Maamaatuaihutapu, Keitapu.
The Marquesas form an isolated group of small islands in the Central South Pacific where quasi-permanent biological activity is observed. During La Niña events, this biological activity, shown by a net increase of chlorophyll-a concentration (Chl, a proxy of phytoplankton biomass), is particularly strong. It has been hypothesized that this strong activity is due to iron-rich waters advected from the equatorial region to the Marquesas by tropical instability waves (TIWs). Here we investigate this hypothesis over 18 years by combining satellite observations, re-analyses of ocean data, and Lagrangian diagnostics. Four La Niña events ranging from moderate to strong intensity occurred during this period, and our results show that the Chl plume within the...
Tipo: Text
Palavras-chave: Tropical instability waves; La Nina; Chlorophyll-a concentration variability; Ocean colour; Island mass effect; Marquesas islands; Oceanography; Satellite observations.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00437/54858/56346.pdf

Determining bluefin tuna habitat through frontal features in the Mediterranean sea
Provedor de dados: 5
Autores: Royer, Francois; Fromentin, Jean-marc; Farrugio, Henri; Gaspar, Philippe.
The distribution patterns of bluefin tuna schools observed during the STROMBOLI EU project (2000-2002) were analysed in relation to oceanographic conditions. High-resolution radiometers (AVHRR and SeaWiFS) were used on a daily basis to derive maps of environmental variability. An edge detection technique was especially applied to estimate the position of frontal features. Using a variety of geostatistical and point process techniques, we were able to show that the distribution of bluefin schools was partially driven by the occurrence of transient fronts in the Gulf of Lions. This is believed to be mainly a trophic association, since enhanced convergence and retention processes occur at fronts, possibly leading to higher prey densities (e.g. anchovies). The...
Tipo: Text
Palavras-chave: Thunnus thynnus; Aerial survey; Gulf of Lions; Sea surface temperature; Ocean colour; Fronts.
Ano: 2005
URL: http://archimer.ifremer.fr/doc/00194/30504/28914.pdf

Coccolith-derived turbidity and hydrological conditions in May in the Bay of Biscay
Provedor de dados: 5
Autores: Perrot, Laurie; Gohin, Francis; Ruiz-pino, Diana; Lampert, Luis; Huret, Martin; Dessier, Aurelie; Malestroit, Pascale; Dupuy, Christine; Bourriau, Paul.
Coccolithophore blooms occur regularly from April to June in the Bay of Biscay where they have been observed for many years from ocean-colour imagery thanks to the ability of their calcite plates to scatter light. They are easily depicted on interpolated images of non-algal Suspended Particulate Matter (SPM) derived from satellite reflectance data in May, at the time of the PELGAS (PELagique GAScogne) annual surveys. Over the springs 2012 to 2015, the PELGAS surveys provided in-situ data on the turbidity throughout the water column and on the hydrological environment prevailing during the blooms in the vicinity of the continental shelf break. The satellite-derived SPM in the area of coccolithophore blooms was closely related to measured turbidity in the...
Tipo: Text
Palavras-chave: Bay of Biscay; Ocean colour; Suspended particulate matter; Turbidity; Coccoliths; Stratification.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00416/52790/53689.pdf

Association between bluefin tuna schools and oceanic features in the western Mediterranean
Provedor de dados: 5
Autores: Royer, Francois; Fromentin, Jean-marc; Gaspar, P.
We present an analysis of the distribution of bluefin tuna Thunnus thynnus schools spotted during aerial surveys in the Gulf of Lions, in relation to oceanographic features. Bio-optical and thermal properties of the sea surface derived from high-resolution sensors (AVHRR and SeaWiFS) were studied on a daily basis, and an edge-detection technique was applied to detect frontal zones. Geostatistics and point-process analyses were used to evaluate the role of the environment in structuring the spatial pattern of bluefin tuna (BFT). The distribution of schools spotted was strongly non-stationary both in space and time; this is believed to be an effect of the survey design (transect sampling) and the influence of transient oceanographic structures (surface...
Tipo: Text
Palavras-chave: Thunnus thynnus; Gulf of Lions; Point process analysis; Front detection; Sea surface temperature; Ocean colour; Aggregation.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/00000/10786/7585.pdf

Satellite and in situ observations of a late winter phytoplankton bloom, in the northern Bay of Biscay
Provedor de dados: 5
Autores: Gohin, Francis; Lampert, Luis; Guillaud, Jean-francois; Herbland, Alain; Nezan, Elisabeth.
A phytoplankton bloom was observed in late winter 2000, on the continental shelf offshore of southern Brittany, in northwestern Bay of Biscay. This bloom appeared initially along the 120-m isobath, in stratified and clear waters, at the interface between the oceanic water and the plumes of southern Brittany rivers (mainly the Loire and Vilaine). The development of the bloom was triggered by favourable meteorological conditions, characterised by solar irradiance reaching the maximum level expected for that period of the year. Outside of the bloom area, the phytoplankton photosynthesis was irradiance limited: inshore, because of the stronger attenuation of the light; offshore, because of the weak stratification. The hydrological conditions at the onset of...
Tipo: Text
Palavras-chave: Bay of Biscay; Coscinodiscus; Algal bloom; Phytoplankton; Ocean colour; Satellite sensing.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/2003/publication-463.pdf

Influence des ondes de Rossby sur le système biogéochimique de l'Océan Atlantique Nord: Utilisation des données satellites couleur de l'eau et d'un modèle couplé physique/biogéochimie
Provedor de dados: 5
Autores: Charria, Guillaume.
The marine phytoplankton in the ocean represents only less than 1% of global biomass. Phytoplankton performs half of all photosynthesis. This autotrophic biomass in ocean is then an essential element in the climate regulation through processes as carbon dioxide absorption during the photosynthesis. Therefore, we need to estimate precisely this biomass as well as the processes which affect it. Using remotely sensed data (altimetry and ocean colour) and a coupled physical/biogeochemical model (MERCATOR-OPA/NPZDDON), Rossby waves and their influence on phytoplankton biomass are specifically studied in the North Atlantic Ocean. Their features and their influences on surface chlorophyll concentrations were analysed. Through the different mechanisms identified,...
Tipo: Text
Palavras-chave: Coupled physical/biogeochemical modelling; Multi sensor wavelet analysis; Ocean carbon cycle; North Atlantic Ocean; Primary production; Ocean colour; Altimetry; Rossby (or planetary) waves; Planetary waves; Coupled physical/biogeochemical oceanography; Modélisaiton couplée physique/biogéochimie; Analyse en ondelettes multi capteurs; Cycle océanique du carbone; Océan Atlantique Nord; Production primaire; Couleur de l'eau; Altimétrie; Ondes de Rossby ou planétaires; Océanographie couplée physique/biogéochimie.
Ano: 2005
URL: http://archimer.ifremer.fr/doc/2005/these-2454.pdf

The Advantages of Landsat 8-OLI-Derived Suspended Particulate Matter Maps for Monitoring the Subtidal Extension of Amazonian Coastal Mud Banks (French Guiana)
Provedor de dados: 5
Autores: Zorrilla, Noelia Abascal; Vantrepotte, Vincent; Gensac, Erwan; Huybrechts, Nicolas; Gardel, Antoine.
The coast of French Guiana is characterised by the northwestward migration of large mud banks alongshore and by high concentrations of suspended particulate matter (SPM) resulting from the strong influence of the Amazon River outflow. Surface OLI SPM concentration, linked to the footprint of the subtidal part of mud banks due to resuspension and migration processes, was used to develop a method to estimate the location of this footprint. A comparison of the results from this method with those obtained by locating the limit of the wave damping, which characterises muddy coasts, revealed good performance of the method based on recurring SPM values. The migration rates of the mud banks in French Guiana were calculated according to the delimitation of their...
Tipo: Text
Palavras-chave: Suspended matter; Mud banks; Ocean colour; Landsat 8; French Guiana.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00638/74965/75941.pdf

Results from Verification of Reference Irradiance and Radiance Sources Laboratory Calibration Experiment Campaign
Provedor de dados: 5
Autores: Białek, Agnieszka; Goodman, Teresa; Woolliams, Emma; Brachmann, Johannes F. S.; Schwarzmaier, Thomas; Kuusk, Joel; Ansko, Ilmar; Vabson, Viktor; Lau, Ian C.; Maclellan, Christopher; Marty, Sabine; Ondrusek, Michael; Servantes, William; Taylor, Sarah; Van Dommelen, Ronnie; Barnard, Andrew; Vellucci, Vincenzo; Banks, Andrew C.; Fox, Nigel; Vendt, Riho; Donlon, Craig; Casal, Tânia.
We present the results from Verification of Reference Irradiance and Radiance Sources Laboratory Calibration Experiment Campaign. Ten international laboratories took part in the measurements. The spectral irradiance comparison included the measurements of the 1000 W tungsten halogen filament lamps in the spectral range of 350 nm–900 nm in the pilot laboratory. The radiance comparison took a form of round robin where each participant in turn received two transfer radiometers and did the radiance calibration in their own laboratory. The transfer radiometers have seven spectral bands covering the wavelength range from 400 nm–700 nm. The irradiance comparison results showed an agreement between all lamps within ±1.5%. The radiance comparison results presented...
Tipo: Text
Palavras-chave: Ocean colour; Spectral irradiance comparison; Spectral radiance sources comparison; Fiducial reference measurements.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00655/76688/77827.pdf

Quality-control tests for OC4, OC5 and NIR-red satellite chlorophyll-a algorithms applied to coastal waters
Provedor de dados: 5
Autores: Lavigne, H.; Van Der Zande, D.; Ruddick, K.; Cardoso Dos Santos, J.f.; Gohin, Francis; Brotas, V.; Kratzer, S.
Reliable satellite estimates of chlorophyll-a concentration (Chl-a) are needed in coastal waters for applications such as eutrophication monitoring. However, because of the optical complexity of coastal waters, retrieving accurate Chl-a is still challenging. Many algorithms exist and give quite different performance for different optical conditions but there is no clear definition of the limits of applicability of each algorithm and no clear basis for deciding which algorithm to apply to any given image pixel (reflectance spectrum). Poor quality satellite Chl-a data can easily reach end-users. To remedy this and provide a clear decision on when a specific Chl-a algorithm can be used, we propose simple quality control tests, based on MERIS water leaving...
Tipo: Text
Palavras-chave: Ocean colour; Chlorophyll-a algorithms; Coastal waters; Quality control; Algorithm-switching approach; MERIS; OLCI; Sentinel-3.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00675/78758/80933.pdf

Twenty years of satellite and in situ observations of surface chlorophyll-a from the northern Bay of Biscay to the eastern English Channel. Is the water quality improving?
Provedor de dados: 5
Autores: Gohin, Francis; Van Der Zande, Dimitry; Tilstone, Gavin; Eleveld, Marieke A.; Lefebvre, Alain; Andrieux-loyer, Francoise; Blauw, Anouk N.; Bryère, Philippe; Devreker, David; Garnesson, Philippe; Hernandez Farinas, Tania; Lamaury, Yoann; Lampert, Luis; Lavigne, Héloïse; Menet-nedelec, Florence; Pardo, Silvia; Saulquin, Bertrand.
The variability of the phytoplankton biomass derived from daily chlorophyll-a (Chl-a) satellite images was investigated over the period 1998–2017 in the surface waters of the English Channel and the northern Bay of Biscay. Merged satellite (SeaWiFS-MODIS/Aqua-MERIS-VIIRS) Chl-a was calculated using the OC5 Ifremer algorithm which is optimized for moderately-turbid waters. The seasonal cycle in satellite-derived Chl-a was compared with in situ measurements made at seven coastal stations located in the southern side of the English Channel and in the northern Bay of Biscay. The results firstly showed that the satellite Chl-a product, derived from a suite of space-borne marine reflectance data, is in agreement with the coastal observations. For compliance with...
Tipo: Text
Palavras-chave: Satellite remote-sensing; Ocean colour; Phytoplankton; Chlorophyll-a; English Channel; Bay of Biscay; Eutrophication assessment; European marine strategy framework directive.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00513/62514/66811.pdf

Global Retrieval of Diatom Abundance Based on Phytoplankton Pigments and Satellite Data
Provedor de dados: 5
Autores: Soppa, Mariana A.; Hirata, Takafumi; Silva, Brenner; Dinter, Tilman; Peeken, Ilka; Wiegmann, Sonja; Bracher, Astrid.
Diatoms are the major marine primary producers on the global scale and, recently, several methods have been developed to retrieve their abundance or dominance from satellite remote sensing data. In this work, we highlight the importance of the Southern Ocean (SO) in developing a global algorithm for diatom using an Abundance Based Approach (ABA). A large global in situ data set of phytoplankton pigments was compiled, particularly with more samples collected in the SO. We revised the ABA to take account of the information on the penetration depth (Z(pd)) and to improve the relationship between diatoms and total chlorophyll-a (TChla). The results showed that there is a distinct relationship between diatoms and TChla in the SO, and a new global model...
Tipo: Text
Palavras-chave: Ocean colour; Phytoplankton functional types; Diatom; Remote sensing; Chlorophyll-a.
Ano: 2014
URL: https://archimer.ifremer.fr/doc/00290/40075/39289.pdf

Determining ridge and runnel longshore migration rate using Spot imagery
Provedor de dados: 5
Autores: Lafon, V; Dupuis, H; Howa, H; Froidefond, Jm.
High-resolution colour satellite imagery is used to map the morphology and to determine the longshore movements of intertidal ridge and runnel systems that characterise the Atlantic southwest coast of France. A couple of Spot images recorded during the summer of 1989 are processed to extract accurate geographical maps of the coastline defined. in this study, as the level corresponding to the lowest astronomical tide. The coastline extraction method is based on a reflectance model, providing depth measurements that were calibrated in the field. This method enables us to map the coastline regardless of the tide level above the lowest astronomical tide at the moment of the image capture. As this model can be extrapolated to a large area, hen sea water is...
Tipo: Text
Palavras-chave: Télédétection; Couleur de l’océan; Trait de côte; Déplacement des barres littorales; Côte aquitaine; Remote sensing; Ocean colour; Coastline; Ridge and runnel movement; Aquitaine coast.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/00322/43316/42938.pdf

An Ocean-Colour Time Series for Use in Climate Studies: The Experience of the Ocean-Colour Climate Change Initiative (OC-CCI)
Provedor de dados: 5
Autores: Sathyendranath, Shubha; Brewin, Robert; Brockmann, Carsten; Brotas, Vanda; Calton, Ben; Chuprin, Andrei; Cipollini, Paolo; Couto, André; Dingle, James; Doerffer, Roland; Donlon, Craig; Dowell, Mark; Farman, Alex; Grant, Mike; Groom, Steve; Horseman, Andrew; Jackson, Thomas; Krasemann, Hajo; Lavender, Samantha; Martinez-vicente, Victor; Mazeran, Constant; Mélin, Frédéric; Moore, Timothy; Müller, Dagmar; Regner, Peter; Roy, Shovonlal; Steele, Chris; Steinmetz, François; Swinton, John; Taberner, Malcolm; Thompson, Adam; Valente, André; Zühlke, Marco; Brando, Vittorio; Feng, Hui; Feldman, Gene; Franz, Bryan; Frouin, Robert; Gould, Richard; Hooker, Stanford; Kahru, Mati; Kratzer, Susanne; Mitchell, B.; Muller-karger, Frank; Sosik, Heidi; Voss, Kenneth; Werdell, Jeremy; Platt, Trevor.
Ocean colour is recognised as an Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS); and spectrally-resolved water-leaving radiances (or remote-sensing reflectances) in the visible domain, and chlorophyll-a concentration are identified as required ECV products. Time series of the products at the global scale and at high spatial resolution, derived from ocean-colour data, are key to studying the dynamics of phytoplankton at seasonal and inter-annual scales; their role in marine biogeochemistry; the global carbon cycle; the modulation of how phytoplankton distribute solar-induced heat in the upper layers of the ocean; and the response of the marine ecosystem to climate variability and change. However, generating a long time series...
Tipo: Text
Palavras-chave: Ocean colour; Water-leaving radiance; Remote-sensing reflectance; Phytoplankton; Chlorophyll-a; Inherent optical properties; Climate Change Initiative; Optical water classes; Essential Climate Variable; Uncertainty characterisation.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00589/70072/68045.pdf

Proceedings, The Colour of Ocean Data : International symposium on oceanographic data and information management with special attention to biological data, Brussels, Belgium, 25-27 November 2002.
Provedor de dados: 20
The objectives of this symposium were to harmonize ocean colours and languages and create a forum for data managers, scientists and dicision makers with a major interest in oceanography, and ope to everyone interested in ocean data management.
Tipo: Report
Palavras-chave: Oceanographic data; Ocean colour.
Ano: 2004
URL: http://hdl.handle.net/1834/5639