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Registros recuperados: 14
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3D modelling of seasonal evolution of Loire and Gironde plumes on Biscay Bay continental shelf ArchiMer
Lazure, Pascal; Jegou, Anne-marie.
A 3D model of the Atlantic shelf has been developed and applied to study shelf dynamics and evolution of hydrology. The model takes the combined effects of tide, wind, river discharges and surface heat flux into account. Time scales vary from 1 day to several years. Following a brief description of the model and forcing variables, the behaviour of the Loire and Gironde plumes is described, first for winter and spring, then over a period of several years, under realistic forcing. The results show that plume evolution depends on the high Variability of river runoff and winds. Model simulations performed over 7 years (1990 to 1996) have highlighted several features of these plumes: 1) In early winter and periods of high river runoff, plumes usually spread...
Tipo: Text Palavras-chave: Panache; Modélisation; Dynamique du plateau continental; Golfe de Gascogne; River plume; Modelling; Shelf dynamics; Bay of Biscay.
Ano: 1998 URL: http://archimer.ifremer.fr/doc/1998/publication-847.pdf
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Analysis of salinity measurements near islands on the French continental shelf of the Bay of Biscay ArchiMer
Lazure, Pascal; Jegou, Anne-marie; Kerdreux, Michel.
The Bay of Biscay is characterised by large fresh water inputs from two major rivers, the Loire and the Gironde, with a mean discharge of about 900 m(3)/s. To describe the spatial and temporal variability of the Loire and Gironde plumes, continuous salinity measurements were made at 4 locations on French coastal islands over periods lasting at least two years. These islands are located at a distance from the large local gradients linked to local inputs. Whereas sea surface salinity in the centre of the Bay of Biscay is 35.6, salinities at the coast vary between about 35 in summer to occasionally less than 30 in late winter or in spring. Minimum salinities do not occur at the same time along the coast, indicating a strong spatial gradient. Near the Loire...
Tipo: Text Palavras-chave: Bay of Biscay; Continental shelf; River plume; Seasonal variability; Salinity; Hydrology.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-3957.pdf
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Biogeochemical modelling in the Bay of Seine (France): an improvement by introducing phosphorus in nutrient cycles ArchiMer
Guillaud, Jean-francois; Andrieux-loyer, Francoise; Menesguen, Alain.
As part of the French National Programme for Coastal Oceanography, this paper focuses on improvement of biogeochemical modelling in the: Bay of Seine (Eastern Channel), by introducing phosphorus in nutrient cycles. The Bay of Seine receives the Seine river, which exhibits very high nutrient concentrations, and this coastal zone constitutes a typical case of eutrophication in a river plume area. In terms of analyses, sequential extraction and analysis of sedimentary phosphorus were used in order, to measure various forms of particulate phosphorus in suspended matter and sediment (calcium-bound phosphate, Fe/Al-bound phosphate, exchangeable phosphate and organic phosphorus). In the modelling approach, the Bay is divided into 42 boxes and a two-layer,...
Tipo: Text Palavras-chave: Bay of Seine; Phytoplankton; Phosphorus; River plume; Biological two layer box model.
Ano: 2000 URL: http://archimer.ifremer.fr/doc/2000/publication-462.pdf
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Contribution of the Amazon River Discharge to Regional Sea Level in the Tropical Atlantic Ocean ArchiMer
Giffard, Pierrick; Llovel, William; Jouanno, Julien; Morvan, Guillaume; Decharme, Bertrand.
Tipo: Text Palavras-chave: Sea level; Amazon River; River plume; Salinity; Model; NEMO; Tropical Atlantic.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00591/70268/68327.pdf
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Effects of waves on coastal water dispersion in a small estuarine bay ArchiMer
Delpey, Matthias; Ardhuin, Fabrice; Otheguy, P.; Jouon, Aymeric.
A three-dimensional wave-current model is used to investigate wave-induced circulations in a small estuarine bay and its impact on freshwater exchanges with the inner shelf, related to stratified river plume dispersion. Modeled salinity fields exhibit a lower salinity surface layer due to river outflows, with typical depth of 1 m inside the bay. The asymmetric wave forcing on the bay circulation, related to the local bathymetry, significantly impacts the river plumes. It is found that the transport initiated in the surf zone by the longshore current can oppose and thus reduce the primary outflow of freshwater through the bay inlets. Using the model to examine a high river runoff event occurring during a high-energy wave episode, waves are found to induce a...
Tipo: Text Palavras-chave: Nearshore dispersion; Wave-current interactions; River plume; Numerical modeling.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00170/28161/26390.pdf
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Experimental study of the Rhone plume. Part I: Physics and dynamics ArchiMer
Broche, P; Devenon, Jean-luc; Forget, P; De Maistre, Jc; Naudin, Jj; Cauwet, G.
The complicated dynamic processes occurring when fluvial waters mix with marine waters control the nature and the fluxes of materials exported tay rivers to the sea. Understanding these processes is of primary importance in evaluating budgets. In wide-open estuarine situations these processes take place under the influence of an intense turbulence induced by tides. Conversely, the Rhone waters spread into the Mediterranean Sea in the form of an easily distinguishable buoyant plume often extending far offshore from the mouth of the river. The aim of this study is to describe the dynamic and hydrological fields on the basis of eulerian VHF radar mapping of surface currents coupled with lagrangian in situ physical or geochemical measurements. This paper...
Tipo: Text Palavras-chave: Panache fluvial; Radar VHF; Rhône; Dynamique; River plume; VHF radar; Rhone; Dynamics.
Ano: 1998 URL: http://archimer.ifremer.fr/doc/00325/43636/43229.pdf
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Low salinity intrusions in the western English Channel ArchiMer
Kelly Gerreyn, B; Hydes, D; Jegou, Anne-marie; Lazure, Pascal; Fernand, L; Puillat, I; Garcia Soto, C.
Low salinity (< 35) surface waters (LSSW) at the southern entrance to the western English Channel (48.5 degrees N, 5.1 degrees W, near Ushant) were observed in late winter (March-April) in three successive years (2002-04) during near continuous ship of opportunity operations. The source of the LSSW is the northward spreading plumes from the Loire (47.5 degrees N, 2.5 degrees W) and Gironde (45.6 degrees N, 1.2 degrees W) along the French Atlantic coast. Fastest plume travel times were associated with northeasterly winds, consistent with Ekman theory. Differences between years in the mean winter (January-March) combined river discharges (D) was consistent with the minimum salinities (S-min) of the LSSW (2004: D = 4211 m(3) s(-1), S-min = 33.68; 2003: D =...
Tipo: Text Palavras-chave: Bay of Biscay; English Channel; River plume; Ferrybox; Low salinity.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-3524.pdf
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Mesoscale hydrological variability induced by northwesterly wind on the French continental shelf of the Bay of Biscay ArchiMer
Puillat, I; Lazure, Pascal; Jegou, Anne-marie; Lampert, Luis; Miller, P.
On the French continental shelf of the Bay of Biscay the variability of the surface salinity distribution has been mainly investigated at the seasonal and inter-annual scales. Here, new mesoscale features such as lower-salinity lenses observed in model results are investigated by hydrological measurements acquired during 8 cruises (1997-2000). These lenses are 50-80 km wide and similar to 30 m thick and occur during westerly to northerly wind events that push offshore the less saline water of river Plumes. These water masses detached from the coast are replaced with upwelled saltier water at the coast, so coastal upwelling is often observed at the same time along Landes and southern Brittany coasts. We show that in addition to the influence of seasonal and...
Tipo: Text Palavras-chave: River plume; Upwelling; Lens; Mesoscale; Salinity.
Ano: 2006 URL: http://archimer.ifremer.fr/doc/2006/publication-3958.pdf
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Modeling 3D Rhone river plume using a higher order advection scheme ArchiMer
Arnoux-chiavassa, S; Rey, V; Fraunie, P.
Effects of discretization scheme on the numerical modeling of 3D Rhone River plume dynamics are investigated. A higher order scheme of total variation diminishing (TVD) type is used to discretize advection terms of both momentum and scalar equations. It is shown that this scheme widely damps the numerical diffusion and improves the representation of the dynamical and density fronts bounding the flow. It enables to accurately investigate the effects of the turbulent diffusion, which was previously masked by the numerical one. Numerical results are also compared to in situ data for two situations related to different wind conditions. For the case without wind stress, associated to supercritical values of the Richardson number, optimized turbulent...
Tipo: Text Palavras-chave: Océanographie côtière; Modèle numérique 3D; Panache fluvial; Écoulements stratifiés; Schémas variation totale décroissante; Coastal oceanography; 3D numerical model; River plume; Stratified flows; Total variation diminishing schemes.
Ano: 2003 URL: http://archimer.ifremer.fr/doc/00321/43259/42990.pdf
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Modulation of sea surface temperature warming in the Bay of Biscay by Loire and Gironde Rivers ArchiMer
Costoya, X.; Fernandez-novoa, D.; Decastro, M.; Santos, F.; Lazure, Pascal; Gomez-gesteira, M..
The influence of Loire and Gironde River discharges over the sea surface temperature (SST) in the eastern Bay of Biscay (0.6º–36.6ºW, 44.2º–47.8ºW) was analyzed by means of two complementary databases (MODIS and OISST1/4). The area influenced by river plume showed a different SST when compared with the adjacent oceanic area for the months when the plume attains its highest extension (December, January, and February). Ocean was observed to warm at a rate of approximately 0.3ºC dec−1 while temperature at the area influenced by the rivers cooled at a rate of −0.15ºC dec−1 over the period 1982–2014. The mere presence of a freshwater layer is able to modulate the warming observed at adjacent ocean locations since the coastal area is isolated from the rest of...
Tipo: Text Palavras-chave: Loire; Gironde; SST; River plume; Warming modulation.
Ano: 2016 URL: http://archimer.ifremer.fr/doc/00311/42172/41472.pdf
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REMOTE SENSING OF SEA SURFACE SALINITY: A CASE STUDY IN THE BURDEKIN RIVER, NORTH-EASTERN AUSTRALIA Gayana
Heron,M.L; Prytz,A; Stieglitz,T; Burrage,D.M.
The principles of remotely sensing sea surface salinity are briefly reviewed. The airborne instrument used for this study is a Scanning Low Frequency Microwave Radiometer (SLFMR). It has spatial resolution of typically 500m (depending on the altitude of the aircraft) and a salinity resolution of about 1 psu. This configuration is suitable for studying the dynamics of river plumes as they form on the continental shelf. The Burdekin River is one of Australia's major rivers with about 2.4% of the annual runoff from the continent. This river is in the dry tropics and has severe transient peaks which last for days to weeks during the summer monsoon season. The case study shows the river plume during growth and decay phases and is supported with in situ vertical...
Tipo: Journal article Palavras-chave: Salinity; Microwave radiometer; Airborne; Remote sensing; River plume; Burdekin River.
Ano: 2004 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-65382004000200050
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Surface suspended matter off the Rhone river mouth from visible satellite imagery ArchiMer
Forget, P; Ouillon, S.
The quantification of surface Total Suspended Matter (TSM) off the Rhone river mouth is investigated using SPOT-XS and Landsat-TM images collected in November 1994. The method of satellite data calibration from in situ measurements is discussed. It is based on TSM concentration measurements through filtration of surface water samples and on radiometric data collected with a 256-channel spectroradiometer in the range 400-1100 nm. Empirical relationships between reflectance and TSM concentration are established by linear regression analysis of the data. These relationships are then applied to the image data corrected from atmospheric and surface effects. A good agreement, within a factor of less than two, was found on derived TSM concentration values as...
Tipo: Text Palavras-chave: Réflectance; Matière en suspension; Télédétection; Panache fluvial; Rhône; Reflectance; Suspended matter; Remote sensing; River plume; Rhone river.
Ano: 1998 URL: http://archimer.ifremer.fr/doc/00325/43637/43228.pdf
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Suspended matter and nutrient gradients of a small-scale river plume in Sepetiba Bay, SE-Brazil BABT
Rodrigues,Raphael Paiva; Knoppers,Bastiaan Adriaan; Souza,Weber Friederichs Landim de; Santos,Elisamara Sabadini.
Coastal river plumes represent one of the final stages of material transport across the land-sea interface. Most studies, however have focused on the behavior of medium to large sized river plumes of coastal-shelf waters, whereas small sized river plumes acting within estuaries have been neglected. This study addressed the behavior of suspended particulate matter (SPM), dissolved inorganic nutrients (DIN, DIP and DSi) and Chlorophyll a (Chl. a) of a small sized river plume derived from the closely lain São Francisco and Guandú river channels, set in the Sepetiba Bay estuary, SE-Brazil. Two surface water sampling campaigns were conducted, one in January 2003 (humid summer conditions) and the other in June 2003 (dry winter conditions). On both occasions, the...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Suspended matter; Nutrients; Estuarine gradients; River plume; Sepetiba Bay; SE-Brazil.
Ano: 2009 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132009000200030
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The role of phosphorus on planktonic production of the Gironde plume waters in the Bay of Biscay ArchiMer
Labry, Claire; Herbland, Alain; Delmas, Daniel.
More and more studies emphasize the status of phosphorus (P) as the principal limiting nutrient of phytoplankton growth, especially in coastal waters under the influence of freshwater discharges. The purpose of the present paper is to investigate the role of P on planktonic production in the waters influenced by the Gironde discharges; the Gironde being one of the two largest rivers on the French Atlantic coast. The survey is based on several cruises made in 1998 and 1999. Two different patterns were observed for waters with salinity below and above 34.5. For waters with salinity <34.5. P was found to be the first limiting nutrient of winter and spring phytoplankton blooms, based on undetectable phosphate (<20 nM), high NO3 : PO4 ratios, typically...
Tipo: Text Palavras-chave: Bay of Biscay; River plume; Salinity; Water quality analysis; Phytoplankton; Planktonic production.
Ano: 2002 URL: http://archimer.ifremer.fr/doc/2002/publication-690.pdf
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