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| Registros recuperados: 76 | |
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| 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 |
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| Carlier, Antoine; Chauvaud, Laurent; Van Der Geest, Matthijs; Le Loc'H, Francois; Le Duff, Michel; Vernet, Marc; Raffray, Jean; Diakhate, Djibril; Labrosse, Pierre; Wague, Abdoulaye; Le Goff, Clement; Gohin, Francis; Chapron, Bertrand; Clavier, Jacques. |
| Banc d’Arguin (BA), Mauritania, is a nationally protected shallow gulf > 10,000 km2 between the Sahara desert and the upwelling system off the Mauritanian coast. In the southeast, BA consists of a 500 km2 tidal flat, the most important wintering site for shorebirds using the East Atlantic Flyway. The Mauritanian upwelling-driven phytoplankton production supports the most productive fisheries worldwide, but little is known about its trophic role in the functioning of the inshore BA food web. Using stable isotopes as trophic tracers to distinguish between upwelling-driven phytoplankton, open ocean phytoplankton, and benthic primary producers, we assessed the spatial extent to which the inshore BA food web is fuelled by upwelling-driven phytoplankton... |
| Tipo: Text |
Palavras-chave: Banc d'Arguin; West Africa; Food web structure; Remote sensing; Stable isotope; Upwelling. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00269/37999/36078.pdf |
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| Gohin, Francis; Le Bec, Claude; Cutting, Jane. |
| Karenia mikimotoi is a dinoflagellate common in the Eastern North Atlantic Ocean, particularly in summer. Recent K. mikimotoi blooms in Western Ireland (Silke et al., 2005), Scottish waters (Davidson et al., 2006), and the English Channel (Vanhoutte-Brunier et al., 2008) have been reported and described. This dinoflagellate is feared as it may impact the marine animal population directly, through its haemolitic cytotoxin, or indirectly through hypoxia during the degradation of the bloom when its biomass is high. In 2003, a major K. mikimotoi bloom, visible from space, occurred from the end of June to the beginning of August offshore in the Western English Channel. The bloom started between Northern Brittany and Cornwall. It then developed eastward as the... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00178/28883/27369.pdf |
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| Menesguen, Alain; Gohin, Francis. |
| Accumulation of heat, or dissolved substances (nutrients, pollutants, etc.), or fine suspended particles in a water body is a key process in the functioning of aquatic ecosystems and their resistance to perturbations. In complex and wide open environments such as marine ecosystems, net accumulation is not only linked to the local renewal capacity of the water body, but also to the partial recirculation of water due to convective cells of various sizes. The English Channel, which can be considered as mainly dominated by tidal movements, exhibits such a complex quasi-permanent long-term circulation, made of a central "river" bordered with a lot of nested gyres. Here, we show that structures visible on satellite images of SST (Sea Surface Temperature),... |
| Tipo: Text |
Palavras-chave: Remote sensing; Suspended Particulate Matter; Chlorophyll; SST; Retention structures; Tidal residual circulation; Steady state model; English Channel. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-2181.pdf |
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| Gohin, Francis; Cavanie, Alain; Ezraty, Robert. |
| Although estimation of the total ice concentration from special sensor microwave imagers (SSM/I) has proven to be successful, none of the various algorithms developed to discriminate new and older ice provide satisfying results. While the strong contrast between the emissivity of sea ice and that of open water can be utilized to provide reliable estimators of the total ice concentration, passive microwave characteristics of second-year and multiyear ice may locally evolve in different ways, even during the cold season. Scatterometers, as the active microwave instrument in wind mode (AMI-wind) on board the European Remote Sensing Satellites (ERS), provide backscatter data which have a higher sensitivity to the surface topography of ice and a better... |
| Tipo: Text |
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| Ano: 1998 |
URL: http://archimer.ifremer.fr/doc/00447/55848/58406.pdf |
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| Rivier, Aurelie; Guillou, Nicolas; Chapalain, Georges; Gohin, Francis. |
| Concentration of near-surface suspended particulate matter (SPM) is a key parameter for the characterization of sediment dynamics and the quantification of light in the water column for hydrological and biological modeling in coastal seas. The influences of tides and wind-generated surface-gravity waves on non-algal near-surface SPM in the English Channel have recently been identified by Rivier et al. (2012) on the basis of statistical models applied to a large satellite dataset. The present study extends this analysis by comparing satellite images and numerical model predictions of non-algal near-surface SPM. Satellite images are MODIS and MERIS remote-sensing reflectance processed by the IFREMER semi-analytical algorithm (Gohin et al., 2011). These data... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00108/21959/19553.pdf |
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| Gle, C; Del Amo, Y; Bec, B; Sautour, B; Froidefond, J; Gohin, Francis; Maurer, Daniele; Plus, Martin; Laborde, P; Chardy, P. |
| Phytoplankton dynamics were assessed in the macrotidal ecosystem of Arcachon Bay through high-frequency surveys over a 5-year period in order to characterize typology of environmental conditions at the onset of the productive period. Temporal variations of hydrological and biological parameters were examined in external and internal waters of the lagoon, during the winter-spring periods from 1999 to 2003. An additional survey was performed during winter-spring 2005 in order to study the vertical structure of the water column. The occurrence of winter phytoplankton blooms between January and March emerged as a recurrent event. The early onset of the productive period is influenced by the biological functioning of adjacent Bay of Biscay oceanic waters. It is... |
| Tipo: Text |
Palavras-chave: Macrotidal ecosystem; Phytoplankton inoculum; Onset; Winter blooms. |
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-3513.pdf |
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| 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 |
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| Polsenaere, Pierre; Soletchnik, Patrick; Le Moine, Olivier; Gohin, Francis; Robert, Stephane; Pepin, Jean-francois; Stanisiere, Jean-yves; Dumas, Franck; Bechemin, Christian; Goulletquer, Philippe. |
| In the context of global change, increasing mariculture production has raised particular concerns regarding its environmental impact and sustainability. Molluscs and particularly blue mussel account for a significant part of this total production. Although blue mussels are considered as pretty resilient to environmental disturbances, we report in this study an unprecedented mussel mortality event that occurred during the winter 2014 in the Breton Sound. 9000 metric tonnes of mussels were lost and mortality rates up to 100% were recorded at some farming areas. Through a coupling approach, the present work aimed to better understand the potential environmental drivers associated to those mortalities. Firstly we analysed long-term in situ and satellite data... |
| Tipo: Text |
Palavras-chave: Mytilus edulis mortalities; Climate change; Breton sound; Long-term monitoring; Hydrodynamic modelling; Vibriosis. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00376/48708/49083.pdf |
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| Baretta-bekker, Hanneke; Sell, Anne; Marco-rius, Francisco; Wischnewski, Julia; Walsham, Pamela; Malin Mohlin, Linda; Wesslander, Karin; Ruiter, Hans; Gohin, Francis; Enserink, Lisette. |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00398/50911/51686.pdf |
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| Rivier, Aurelie; Gohin, Francis; Bryere, Philippe; Petus, Caroline; Guillou, Nicolas; Chapalain, Georges. |
| The study of water clarity is essential to understand variability in biological production, particularly in coastal seas. The spatial and temporal variability of non-algal suspended particulate matter (SPM) in surface waters of the English Channel was investigated and related to local forcing by means of a large satellite dataset covering the study area with a spatial resolution of 1.2 km and a daily temporal resolution. This analysed dataset is a time series of non-algal SPM images derived from MODIS and MERIS remote-sensing reflectance by application of an IFREMER semi-analytical algorithm over the period 2003–2009. In a first step, the variability of time series of MODIS images was analysed through temporal autocorrelation functions. Then, non-algal SPM... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00064/17546/15139.pdf |
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| Guillou, Nicolas; Rivier, Aurelie; Gohin, Francis; Chapalain, Georges. |
| The present study investigates the performances of the three-dimensional multicomponent hydro-sedimentary model ROMS (Regional Ocean Modeling System) to predict near-surface suspended sediment concentrations (SSC) in the English Channel (western Europe). Predictions are assessed against satellite-retrieved observations from raw MODIS and MERIS images for the year 2008 characterized by the highest availability of cloud-free data. Focus is put on improvements obtained with: (1) SSC inputs at the open boundaries; and (2) simple parameterizations of the settling velocity and the critical shear stress. Sensitivity studies confirm the importance of the advection of fine-grained suspended sediments in the central waters of the English Channel exhibiting benefits... |
| Tipo: Text |
Palavras-chave: ROMS; Satellite; MERIS; MODIS; Tide; Wave. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00276/38766/37307.pdf |
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| Registros recuperados: 76 | |
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