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| Registros recuperados: 84 | |
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| Dussauze, Morgan; Menesguen, Alain; Dumas, Franck. |
| Two techniques of tracking are compared for delineating the marine area impacted by a river plume. The first one uses a simple conservative tracer released in the river during a several year long period: the probability density function of the tracer concentration in each mesh of the model is used to map 3 characteristic descriptors of the freshwater influence (10%, 50% and 90% percentiles). The second one uses a signature of the river attached to a state variable of a biogeochemical model (e.g. the Dissolved Inorganic Nitrogen components), which can be followed in space and time in the various nitrogenous state variables. Departure between the two methods increases when tracking of nitrogen is considered in biogeochemical forms more and more distant from... |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00068/17892/15423.pdf |
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| Thomas, Yoann; Dumas, Franck; Andrefouet, Serge. |
| The black-lip pearl oyster (Pinctada margaritifera) is cultured extensively to produce black pearls, especially in French Polynesia atoll lagoons. This aquaculture relies on spat collection, a process that experiences spatial and temporal variability and needs to be optimized by understanding which factors influence recruitment. Here, we investigate the sensitivity of P. margaritifera larval dispersal to both physical and biological factors in the lagoon of Ahe atoll. Coupling a validated 3D larval dispersal model, a bioenergetics larval growth model following the Dynamic Energy Budget (DEB) theory, and a population dynamics model, the variability of lagoon-scale connectivity patterns and recruitment potential is investigated. The relative contribution of... |
| Tipo: Text |
Palavras-chave: Pearl oyster; Lagoon; Biophysical modelling; Connectivity; Population dynamics; DEB model. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00321/43192/42926.pdf |
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| Bennis, Anne-claire; Dumas, Franck; Ardhuin, Fabrice; Blanke, Bruno. |
| The mechanics of rip currents are complex, involving interactions between waves, currents, water levels and the bathymetry, that present particular challenges for numerical models. Here, the effects of a grid-spacing dependent horizontal mixing on the wave-current interactions are studied. Near the shore, wave rays diverge from channels towards bar crests because of refraction by topography and currents, in a way that depends on the rip current intensity which is itself modulated by the horizontal mixing. At low resolution with the grid-spacing dependent horizontal mixing, the wave motion is the same for both coupling modes because the wave deviation by the currents is weak. In high resolution case, however, classical results are found with the stabilizing... |
| Tipo: Text |
Palavras-chave: Numerical modeling; Rip currents; Turbulence modeling; Wave-current interactions. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00601/71288/69695.pdf |
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| Petton, Sebastien; Pouvreau, Stephane; Dumas, Franck. |
| Coastal waters are subject to great environmental and anthropogenic pressures. The diffusion and the transport of these waters are a key element for environmental, ecological and economic management. There are numerous indicators of hydrological characteristics based on theories of transport time scale. However, these indicators strongly depend on the geographical shape of the studied area and tend to give information after long integration time periods, generally on the order of weeks. Here, to qualify a coastal area’s dispersion more precisely, we combined two Lagrangian approaches and estimated a local diffusivity. This paper presents the numerical implementation and the results obtained over a tidally flushed, semi-enclosed water body located at... |
| Tipo: Text |
Palavras-chave: Hydrodynamic model; Lagrangian analysis; Barycentric repositioning method; Local diffusivity. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00609/72068/70919.pdf |
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| Perrot, Thierry; Rossi, Nadege; Menesguen, Alain; Dumas, Franck. |
| First recorded in the 1970s, massive green macroalgal blooms have since become an annual recurrence in Brittany, France. Eutrophication (in particular to anthropogenic nitrogen input) has been identified as the main factor controlling Ulva ‘green tide’ events. In this study, we modelled Ulva proliferation using a two-dimensional model by coupling hydrodynamic and biological models (coined ‘MARS-Ulves’) for five sites along the Brittany coastline (La Fresnaye Bay, Saint-Brieuc Bay, Lannion Bay, Guissény Bay and Douarnenez Bay). Calibration of the biological model was mainly based on the seasonal variation of the maximum nitrogen uptake rate (VmaxN) and the half-saturation constant for nitrogen (KN) to reproduce the internal nutrient quotas measured in situ... |
| Tipo: Text |
Palavras-chave: 2D model; Ulva; Eutrophication; Brittany coastal waters; Tracers; Nutrient reductions. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00171/28268/26517.pdf |
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| Bennis, Anne-claire; Ardhuin, Fabrice; Dumas, Franck. |
| Many theoretical approaches and implementations have been proposed for the coupling of the three-dimensional ocean circulation with waves. The theoretical models are reviewed and it is shown that the formulation in terms of the quasi-Eulerian velocity circumvents the essential difficulty of alternative formulations for the Lagrangian mean velocity. Namely, models based on this Lagrangian velocity require an estimation of wave-induced motions to first order in the horizontal gradients of the wave field in order to estimate the vertical flux of wave pseudo-momentum. So far, only three-dimensional wave models have been able to provide these estimates, and all published theories based on the simpler Airy theory are not consistent at the leading order, because... |
| Tipo: Text |
Palavras-chave: Wave-current coupling; Radiation stresses; MARS3D; WAVEWATCH III. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00056/16705/14198.pdf |
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| Plus, Martin; Dumas, Franck; Stanisiere, Jean-yves; Maurer, Daniele. |
| A numerical model (MARS-2D) was developed, with the aim of describing the hydrodynamics that prevail in Arcachon Bay. Direct model results as well as derived mixing and transport time-scales (tidal prism, local and integrated flushing times, age of water masses), were used to understand the behaviour of water masses and exchanges between the Bay and its frontiers. Particular attention was paid to the processes that drive the hydrodynamics (tides, wind and rivers), in order to understand their respective influence. The Arcachon Bay hydrodynamic system appears primarily to be highly influenced by tides; secondarily, by winds. About two third of the lagoon total volume is flushed in and out at each tidal cycle, which represent a mean tidal prism of 384... |
| Tipo: Text |
Palavras-chave: Arcachon Bay; Tracer; Age of seawater; Flushing time; Tidal prism; Residual fluxes; Hydrodynamics. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-6424.pdf |
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| Garreau, Pierre; Dumas, Franck; Louazel, Stephanie; Stegner, A.; Le Vu, B.. |
| Mesoscale dynamics in the Mediterranean Sea have been investigated for years and anticyclonic eddies are regularly observed features in the Algerian Basin. Here, we used the AMEDA eddy detection algorithm to track and monitor a particular anticyclonic eddy from its birth to its death. The analysis of remote‐sensing datasets (AVISO and SST) revealed that this anticyclone split from an Algerian eddy in October 2015, interacted with the North Balearic Front and merged seven months later, in May 2016, with a similar Algerian eddy. In early spring 2016, a field experiment during the ProtevsMed 2016 cruise thoroughly investigated this eddy, when it was located near the North Balearic Front, taking high‐resolution (Seasoar) hydrological transects, several CTD... |
| Tipo: Text |
Palavras-chave: Western Mediterranean Sea; North Balearic Front; Anticyclonic eddy; Submesoscale observations; Eddy tracking tool; High-resolution sampling. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00469/58068/60466.pdf |
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| Le Gendre, Romain; Soulard, Benoit; Lemonnier, Hugues; Laugier, Thierry; Hubert, Morgane; Desclaux, Terence; Royer, Florence; Le Tesson, Eric; Dumas, Franck; Kayara, Jean-françois. |
| Ce rapport fait partie du projet de recherche PRESENCE (PRessions sur les Ecosystèmes récifaux et lagonaires de Nouvelle-CalédoniE). L'objectif de ce projet est de mieux appréhender le fonctionnement des lagons de Nouvelle-Calédonie à partir d’observations in-situ, de télédétection et de modélisation hydrodynamique. Ce rapport présente les mesures effectuées sur les lagons de Touho à Pouébo situés sur la côte Est de la Province Nord de Nouvelle-Calédonie, secteur sur lequel les connaissances et observations du fonctionnement hydrodynamique étaient assez parcellaires. Les données seront utilisées par la suite pour mieux appréhender la dynamique de ce grand lagon mais également à des fins de calibration et de validation de modèle... |
| Tipo: Text |
Palavras-chave: Mesures; Hydrologie; Courantologie; Hydrodynamique; Hienghène; Hyehen; Pouébo; Pweevo; Modélisation. |
| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00452/56378/58028.pdf |
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| Bennis, Anne-claire; Furgerot, Lucille; Bailly Du Bois, Pascal; Dumas, Franck; Odaka, Tina; Lathuilière, Cyril; Filipot, Jean-francois. |
| Modelling three-dimensional wave-current-turbulence interactions in extreme tidal environments is still challenging and necessary for the development of the tidal industry, particularly for the dimensioning of tidal converters. Following this objective, we focus our study on the most energetic tidal site in Western Europe, the Alderney Race (France). Due to the strong tidal current at this location, wave-current interactions were poorly studied by the past and often neglected. We propose to assess how they impact the Alderney Race hydrodynamic by the use of numerical modelling and in-situ measurements. In this study, the following wave-current interactions were observed: (i) Stokes drift effects inducing an increase/decrease in the current depending on the... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00599/71155/73092.pdf |
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| Cayocca, Florence; Verney, Romaric; Petton, Sebastien; Caillaud, Matthieu; Dussauze, Morgan; Dumas, Franck; Le Roux, Jean-francois; Pineau-guillou, Lucia; Le Hir, Pierre. |
| The rising interest in environmental and ecosystem dynamics have lead coastal oceanographers to not only investigate the “traditional” physical parameters describing the ocean state and its dynamics (e.g. temperature, salinity, currents, water levels in coastal areas), but to also account for the dynamics of parameters describing its biogeochemical components. To that end, MARS3D regional and coastal modelling system has been coupled to ecosystem modules (ECO-MARS3D, ECO3M) as well as sediment dynamics modules (MARS3D-SEDIM): sediment, nutrient and primary production contents can be considered as the lower level environment and ecosystem descriptors of the “biogeochemical” ocean. Early investments into physical and biological analysis at the regional scale... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00194/30572/29015.pdf |
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| Bailly Du Bois, P.; Dumas, Franck; Solier, L.; Voiseux, C.. |
| Appropriate field data are required to check the reliability of hydrodynamic models simulating the dispersion of soluble substances in the marine environment. This study deals with the collection of physical measurements and soluble tracer data intended specifically for this kind of validation. The intensity of currents as well as the complexity of topography and tides around the Cap de La Hague in the centre of the English Channel make it one of the most difficult areas to represent in terms of hydrodynamics and dispersion. Controlled releases of tritium-in the form of HTO-are carried out in this area by the AREVA-NC plant, providing an excellent soluble tracer. A total of 14,493 measurements were acquired to track dispersion in the hours and days... |
| Tipo: Text |
Palavras-chave: Modelling; Data collection; Tritium; Dispersion; Tidal dynamics; English Channel. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00077/18775/16484.pdf |
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| Muller, Heloise; Blanke, Bruno; Dumas, Franck; Mariette, Vincent. |
| This paper describes the surface Lagrangian residual circulation (LRC) over 2.5 day intervals in the Iroise Sea, west of France, and evaluates, for operational purposes, the influence of the different physical mechanisms that govern it. The method consists of the calculation of water displacements with a diagnostic Lagrangian tool that computes the trajectories of numerical particles in a given velocity field. The LRC is inferred from trajectories integrated over five M2 tidal cycles. The analysis is applied to both gridded genuine current measurements and ocean model outputs: the sea surface currents are derived from high-frequency (HF) radar measurements and from MARS, a 3-D regional ocean model used here in idealized configurations. To substantiate the... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00011/12220/9004.pdf |
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| Herbert, Gaelle; Garreau, Pierre; Garnier, Valerie; Dumas, Franck; Caillaud, S.; Chanut, Jerome; Levier, Bruno; Aznar, Roland. |
| In order to favour the downstream from the European MyOcean service of large scale ocean forecasts to the national service of coastal ocean forecasts, studies of new methods improving the downscaling between global or regional ocean models and coastal ones are in progress. In the framework of PREVIMER and MyOcean projects respectively, IFREMER and Mercator Ocean studied in parallel the impact of the spectral nudging method. In the present work, the performance of spectral nudging was assessed using two regional hydrodynamic models: one of Mediterranean Sea and one of the Iberia-Biscay-Ireland (IBI) area. They are both forced by a coarser global circulation model (GCM) (PSY2V4/Mercator Ocean). This technique prevents large and unrealistic departures between... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00197/30794/29162.pdf |
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| Perrot, Thierry; Menesguen, Alain; Dumas, Franck. |
| Every spring and summer, and for two decades, mass-blooms produced by a green alga of the genus Ulva, have been polluting some localities along the Brittany coasts. The main aspect of the nuisance lies in the stranding and further decomposition of large amounts of algae along recreational zones inducing visual and odoriferous pollution. Sites which are favourable to Ulva mass-blooms are shallow areas where water exchange with the open sea is slow (weak residual drift of water masses and long residence time). Drifting algae and nutrients are both trapped in these zones thus allowing Ulva thalli to be kept in good cultivation conditions. In collaboration with Ifremer, the so-called “MARS-ulve” ecological model (coupling the biochemical model ELISE with the... |
| Tipo: Text |
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| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00480/59150/61779.pdf |
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| Bennis, A. -c.; Dumas, Franck; Blanke, Bruno. |
| The mechanics of rip currents are complex, involving interactions between waves, currents, water levels and bathymetry that pose particular challenges for numerical modeling. Horizontal turbulent diffusion in a rip system is difficult to measure using dye dilution or surfzone drifters, as shown by the range of published values for the horizontal diffusion coefficient. Here, we studied the effects of horizontal mixing on wave–current interactions by testing several diffusivity estimates in a fully coupled 3D wave–current model run at two different spatial resolutions. Published results using very low diffusion have found that near the shore the wave rays converge towards the rip channel because of refraction by the currents. We showed that this process is... |
| Tipo: Text |
Palavras-chave: Coastal ocean modelling; Nearshore processes; Rip currents; Wave current interactions; Horizontal mixing. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00309/42060/41530.pdf |
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| Plus, Martin; Auby, Isabelle; Maurer, Daniele; Trut, Gilles; Del Amo, Y.; Dumas, Franck; Thouvenin, Benedicte. |
| This study presents an assessment of the contributions of various primary producers to the global annual production and N/P cycles of a coastal system, namely the Arcachon Bay, by means of a numerical model. This 3D model fully couples hydrodynamic with ecological processes and simulates nitrogen, silicon and phosphorus cycles as well as phytoplankton, macroalgae and seagrasses. Total annual production rates for the different components were calculated for different years (2005, 2007 and 2009) during a time period of drastic reduction in seagrass beds since 2005. The total demand of nitrogen and phosphorus was also calculated and discussed with regards to the riverine inputs. Moreover, this study presents the first estimation of particulate organic carbon... |
| Tipo: Text |
Palavras-chave: Primary production; Macrophyte; Phytoplankton; Biogeochemical cycle; Physical-ecological coupled model; Arcachon bay. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00278/38963/37503.pdf |
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| Registros recuperados: 84 | |
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