Consulta: subjectFacets:"Chlorophyll-a"
Registros recuperados: 16
Data/hora: 08/06/2024 18:49:39

Spatial and temporal trends in the distribution of macronutrients in surface waters of the Drake Passage
Provedor de dados: 67
Autores: Paparazzo,Flavio E.; Alder,Viviana A.; Schloss,Irene R.; Bianchi,Alejandro; Esteves,Jose L.
The Drake Passage (DP) links the Southern Pacific and Atlantic Oceans, and acts as a physical narrowing for the largest current of the World Ocean, the Antarctic Circumpolar Current (ACC). This result in a constriction of the main circumpolar fronts related to the ACC: the Subantarctic Front, the Polar Front, the Southern Antarctic Circumpolar Current Front and the Continental Water Boundary Front. Previous studies showed that the DP is a high-nutrient low-chlorophyll (HNLC) region, but studies on the interannual and seasonal macronutrients' fluctuations in relation with chlorophyll and frontal areas in the DP are scarce. This study analyzes the spatial and temporal trends of nitrate, phosphate, and silicate on surface samples from 113 oceanographic...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Nitrate; Phosphate; Silicate; Chlorophyll-a; Temperature; Salinity; Antarctic fronts; Antarctic zones; Seasonal variation; Interannual variation.
Ano: 2016
URL: http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S1667-782X2016000100004

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

Ocean currents and gradients of surface layer properties in the vicinity of the Madagascar Ridge (including seamounts) in the South West Indian Ocean
Provedor de dados: 5
Autores: Vianello, Patrick; Ternon, Jean-francois; Demarcq, Herve; Herbette, Steven; Roberts, Michael J.
This work is part of the MADRidge Project special issue which aims to describe pelagic ecosystems in the vicinity of three prominent shallow seamounts in the South West Indian Ocean: one here named MAD-Ridge (240 m below the surface) plus Walters Shoal (18 m) on the Madagascar Ridge, and La Pérouse (60 m) on the abyssal plain east of Madagascar. The three span latitudes 20°S and 33°S, some 1500 km. The study provides the background oceanography for the once-off, multidisciplinary snapshot cruise studies around the seamounts. As life on seamounts is determined by factors such as summit depth, proximity to the light layers of the ocean, and the ambient circulation, a first description of regional spatial-field climatologies (16–22 years) and monthly...
Tipo: Text
Palavras-chave: South West Indian Ocean; Madagascar Ridge; Seamounts; Walters shoal; Sea surface temperature; Eddy kinetic energy; Mixed layer depth; Chlorophyll-a; Geostrophic currents.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00634/74581/74476.pdf

Évaluation du descripteur 5 « Eutrophisation » en France métropolitaine. Rapport scientifique pour l’évaluation 2018 au titre de la DCSMM
Provedor de dados: 5
Autores: Devreker, David; Lefebvre, Alain.
This report is the second assessment of French marine water eutrophication status (descriptor 5) done in the framework of the MSFD. The goal of this report is to determine if French marine water reach the Good Ecological State as defined by the MSFD. It stands next to the initial evaluation made in 2012, from which it is an update. It introduces the second cycle of the Marine Environment Action Program. It shows that French marine waters, behind the 12 nm line, reach the GES as defined by the MSFD. Problems link to eutrophication occurs in marine waters above the 12 nm, where 6.5% of the area do not reach the GES.
Tipo: Text
Palavras-chave: DCSMM; Eutrophisation; Évaluation; Bon Etat Ecologique; Seuils; Indicateurs; Nutriments; Chlorophylle-a; Oxygène; Turbidité; Macroalgues; Pressions écologiques; MSFD; Eutrophication; Assessment; Good Environmental Status; Thresholds; Indicators; Nutrients; Chlorophyll-a; Oxygen; Turbidity; Macroalgae; Ecological pressures.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00437/54868/56361.pdf

Development of a coastal upwelling front driven by advection and topographic effects in the North Sea-Baltic Sea transition
Provedor de dados: 5
Autores: Lund-hansen, Lc; Vang, T.
Upwelling of cold. saline, and nutrient rich water was observed in late September 1999 along an east-west transect in the SW Kattegat. The Kattegat forms part of the transitional zone between the high saline North Sea and the low saline Baltic Sea. The upwelling occurred after an extended period of northward flow and eastern winds in the Kattegat, that changed into a southward flow as wind ceased. The upwelling was the result of a combination of high current speeds and bottom topography whereby the high-speed inflow water was forced towards the surface at the slope. Nutrient data show that the upwelling brought nutrient rich bottom water to the light exposed surface and a related strong (1943.5 ml(-1)) bloom of Pseudo-nitzschia pseudodelicatissima was...
Tipo: Text
Palavras-chave: Courant; Upwelling; Front; Fluorescence; Chlorophylle-a; Inflow; Upwelling; Frontal structure; Fluorescence; Chlorophyll-a.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/00321/43249/42980.pdf

Towards Chl-a Bloom Understanding by EM-based Unsupervised Event Detection
Provedor de dados: 5
Autores: Poisson Caillault, Emilie; Lefebvre, Alain.
Marine water quality monitoring and subsequent management require to know when a specific event like harmful algae bloom may occur and which environmental conditions and pressures lead to this event. So, event detection and its dynamic understanding are crucial to adapt strategy. An algorithm is proposed to identify curves mixture and their dynamics features - initiation, duration, peaks and ends of the event. The approach is fully unsupervised, it requires no tuning parameters and is based on Expectation Maximization process to estimate the most robust mixture according to fixed criteria. A complete framework is proposed to deal with a univariate time series with missing data. The approach is applied on Chlorophyll- a series collected weekly since 1989....
Tipo: Text
Palavras-chave: Time series; Event detection; Expectation-Maximisation; Phenology; Chlorophyll-a; Phaeocystis.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00435/54679/56097.pdf

Détection satellitaire et modélisation opérationnelle de la production végétale non-fixée dans la bande côtière bretonne
Provedor de dados: 5
Autores: Penard, Cédric.
The negative impact of the man on the environment unquestionably increases. The coastal environment as a whole is the maritime environment which is the most exposed to man-made eutrophication. For instance, nitrate loads to coastal waters off Brittany (France) have increased 10 times (from 3 to s 30mg L-1NO3) during the four last decades. Eutrophication of this coastal zone is now a recurrent problem, more and more worrying. This eutrophication exhibits two main forms : " green tides ", which are caused by local proliferations and stranding of green macro-algae (particularly the Ulva species) in nitrogen-enriched areas ; phytoplanktonic blooms, which are responsible for coloured water events, toxic species can be present (Pseudo-Nitzschia, Alexandrium,...
Tipo: Text
Palavras-chave: Bande côtière bretonne; Modèle couplé hydrodynamique-biogéochimie; Nutriments; Chlorophyllea; Production primaire; Eutrophisation; Modèle opérationnel; Pseudo-Nitzschia; French Brittany coastal shelf; Hydrodynamical biogeochemical coupled model; Nutrients; Chlorophyll-a; Primary production; Eutrophication; Operational model; Pseudo-Nitzschia.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00015/12603/9481.pdf

Regional objective analysis for merging MERIS, MODIS/Aqua and SeaWiFS Chlorophyll-a data from 1998 to 2008 on the European Atlantic Shelf at a resolution of 1.1Km.
Provedor de dados: 5
Autores: Saulquin, Bertrand; Gohin, Francis; Garello, Rene.
In this paper we define the method used to merge high resolution multi-sensor chlorophyll-a data on the Ireland-Biscay-Iberia Regional Ocean Observing System (IBI-ROOS) area at a resolution of 0.015 degrees. The method is based on geostatistics and is known as kriging. The merged variable is the anomaly of chlorophyll-a, the anomaly being defined for a day as the difference between the daily image and the mean historical field for that day. The used chlorophyll-a dataset is derived from the daily level-2 water leaving radiances of the Sea-viewing Wide Field of View Sensor (SeaWiFS) of the Orbview platform, the Moderate Resolution Imaging Spectroradiometer (MODIS) of the Aqua platform and the Medium Resolution Imaging Spectrometer Instrument (MERIS) of the...
Tipo: Text
Palavras-chave: Remote sensing; Chlorophyll-a; Optimal interpolation; Kriging.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/00014/12536/9568.pdf

A Multiparametric Nonlinear Regression Approach for the Estimation of Global Surface Ocean pCO(2) Using Satellite Oceanographic Data
Provedor de dados: 5
Autores: Krishna, Kande Vamsi; Shanmugam, Palanisamy; Nagamani, Pullaiahgari Venkata.
Estimation of the partial pressure of carbon dioxide (pCO(2)) and its space-time variability in global surface ocean waters is essential for understanding the carbon cycle and predicting the future atmospheric CO2 concentration. Until recently, only basin-scale distribution of pCO(2) has been reported by using satellite-derived climatological data due to the lack of models for global-scale applications. In the present work, a multiparametric nonlinear regression (MPNR) for the estimation of global-scale distribution of pCO(2) on the ocean surface is developed using continuous in-situ measurements of pCO(2), chlorophyll-a (Chla) concentration, sea surface temperature (SST), and sea surface salinity (SSS) obtained on a number of cruise programs in various...
Tipo: Text
Palavras-chave: Carbon dioxide; Chlorophyll-a; Multiparametric algorithm; Partial pressure of carbon dioxide; Satellite oceanography; Sea surface salinity; Sea surface temperature.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00676/78842/81152.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

Satellite and In Situ Monitoring of Chl-a, Turbidity, and Total Suspended Matter in Coastal Waters: Experience of the Year 2017 along the French Coasts
Provedor de dados: 5
Autores: Gohin, Francis; Bryère, Philippe; Lefebvre, Alain; Sauriau, Pierre-guy; Savoye, Nicolas; Vantrepotte, Vincent; Bozec, Yann; Cariou, Thibault; Conan, Pascal; Coudray, Sylvain; Courtay, Gaelle; Françoise, Sylvaine; Goffart, Anne; Hernández Fariñas, Tania; Lemoine, Maud; Piraud, Aude; Raimbault, Patrick; Rétho, Michael.
The consistency of satellite and in situ time series of Chlorophyll-a (Chl-a), Turbidity and Total Suspended Matters (TSM) was investigated at 17 coastal stations throughout the year 2017. These stations covered different water types, from relatively clear waters in the Mediterranean Sea to moderately turbid regions in the Bay of Biscay and the southern bight of the North-Sea. Satellite retrievals were derived from MODIS/AQUA, VIIRS/NPP and OLCI-A/Sentinel-3 spectral reflectance. In situ data were obtained from the coastal phytoplankton networks SOMLIT (CNRS), REPHY (Ifremer) and associated networks. Satellite and in situ retrievals of the year 2017 were compared to the historical seasonal cycles and percentiles, 10 and 90, observed in situ. Regarding the...
Tipo: Text
Palavras-chave: Satellite; Coastal monitoring; Chlorophyll-a; Total suspended matter; Turbidity.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00645/75669/76536.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

Balance of nitrogen and phosphorus in a reservoir in the tropical semi-arid region
Provedor de dados: 124
Autores: Andrade,Eunice Maia de; Ferreira,Kássia Crislayne Duarte; Lopes,Fernando Bezerra; Araújo,Isabel Cristina da Silva; Silva,Antônio Givanilson Rodrigues da.
ABSTRACT In relation to the process of eutrophication of water reservoirs, it is necessary to understand the nitrogen and phosphorus supply, as well as they contribute to the eutrophication process. The aim of this research was to quantify the input and the balance of phosphorus and nitrogen, as well as to identify the effect of climate seasonality on dynamics of these nutrients in a reservoir. The campaigns took place from April/2008 to Dec/2012 at the Orós reservoir, located in the semi-arid region of Brazil. Based on dataset it was possible to calculate the inflow and outflow of total nitrogen (TN) and total phosphorus (TP). The reservoir becoming a storage place for the nutrients transported by the flow of water from the drainage network. A total of...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Nutrients source; Mass balance; Chlorophyll-a; Semi-arid eutrophication; Water quality.
Ano: 2020
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-66902020000100420

Indirect method for quantifying the content of photosynthetic pigments in genotypes of dwarf elephant grass - doi: 10.4025/actascianimsci.v35i1.15178
Provedor de dados: 2
Autores: Araújo, Saulo Alberto do Carmo; Universidade Federal dos Vales do Jequitinhonha e Mucuri; Vasquez, Hernan Maldonado; Universiade Estadual do Norte Fluminense “Darcy Ribeiro”; Torres Neto, Alena; Universiade Estadual do Norte Fluminense “Darcy Ribeiro”; Campostrini, Eliemar; Universiade Estadual do Norte Fluminense “Darcy Ribeiro”; Deminicis, Bruno Borges; Universidade Federal do Espírito Santo; Lima, Érico da Silva; Universidade Estadual Paulista “Júlio de Mesquita Filho".
Equations that indirectly associate the rates obtained by chlorophyll meter SPAD-502 to chlorophyll and carotenoids rates of dwarf elephant grass genotype are provided. Leaves of the genotype of dwarf elephant grass were employed. After being collected, they were transported in light-protected styrofoam boxes to the Plant Physiology Laboratory of UENF. Leaf discs of the known area were then extracted. An average of 5 readings/leaf disc were undertaken by portable chlorophyll meter SPAD-502, with 6 discs for each range and distributed according to the following scale: 0-10; 10-20; 20-30; 30-40; 40-50; 50-60. Chlorophyll meter SPAD-502 provides a quick and efficient estimate of total chlorophyll, chlorophyll-a and chlorophyll-b in genotypes of dwarf elephant...
Tipo: Pesquisa de campo; análise laboratorial
Palavras-chave: Ciência Animal; Forragicultura ccarotenoids; Chlorophyll-a; Chlorophyll-b; Chlorophyllometer; Pennisetum purpureum.
Ano: 2013
URL: http://periodicos.uem.br/ojs/index.php/ActaSciAnimSci/article/view/15178

Partitioning of the diffuse attenuation coefficient for photosynthetically available irradiance in a deep dendritic tropical lake
Provedor de dados: 42
Autores: BRANDÃO,LUCIANA P.M.; BRIGHENTI,LUDMILA S.; STAEHR,PETER A.; BARBOSA,FRANCISCO A.R.; BEZERRA-NETO,JOSÉ F.
ABSTRACT We studied the effects of particulate and dissolved optically active components on the attenuation of photosynthetic active radiation (PAR) in a tropical lake. The temporal and spatial distribution of tripton, Chl-a and aCDOM(440) and their relative contribution to the diffuse PAR attenuation coefficient (Kd) was investigated at 21 sites (dry and wet seasons and two intermediate periods) and at monthly interval at 1 pelagic site. Higher values of ​​ Kd were observed during the mixing period, characterized by a higher concentration of tripton and Chl-a compared to the stratified rainy season. In the spatial sampling PAR attenuation was dominated by tripton absorption/scattering (average relative contribution of 79%), followed by Chl-a (average...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: CDOM; Chlorophyll-a; Kd partition; Light attenuation; Tripton.
Ano: 2017
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652017000200469