Consulta: subjectFacets:"Numerical model"
Registros recuperados: 35
Data/hora: 14/06/2024 16:15:21

The influence of torsion on braided rope performance, modelling and tests
Provedor de dados: 5
Autores: Davies, Peter; Durville, Damien; Vu, Thanh Do.
Twist may be introduced accidentally into braided ropes during operations at sea, and it is important to know how this will affect both rope integrity and safety coefficients. This paper describes the use of simulation tools to evaluate how twisting can change the tensile properties of braided ropes. The case of a 300 kN break load 12 strand braided HMPE rope is examined. An original numerical modelling approach is presented, and results are compared with results from tensile tests performed on ropes with different levels of twist. A drop in strength of around 4% per turn per meter, and an increase in elongation, were observed as the number of turns per meter increased, corresponding to progressive removal of the load-bearing capacity of half the braided...
Tipo: Text
Palavras-chave: Torsion; Rope; Braid; Numerical model.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00346/45696/45354.pdf

A numerical modelling study of upwelling filaments off the NW African coast
Provedor de dados: 5
Autores: Stevens, I; Johnson, J.
A fine resolution (1/12degrees x 1/12degrees) primitive equation limited area model is constructed for the region off NW Africa in the eastern North Atlantic to examine the generation of cool upwelling filaments. A seasonal shift in the trade wind pattern leads to coastal upwelling and an equatorward coastal current. The filaments form at four preferred locations along the NW African coast between 25degreesN and 35degreesN, the largest filament being at Cape Ghir. The generation mechanism for the filaments is similar to the one proposed for filaments in the California current system. As a result of baroclinic instability meanders develop on the coastal current and transport cool upwelled water offshore to form the filaments. During the relaxation phase of...
Tipo: Text
Palavras-chave: Modèle numérique; Upwelling; Meso-échelle; Afrique Nord-Ouest; Cape Ghir; Numerical model; Coastal upwelling; Mesoscale features; NW Africa; Cape Ghir.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/00321/43247/42978.pdf

Impact du régime du barrage d'Arzal sur la stratification a l'embouchure de la Vilaine : étude par modélisation numérique
Provedor de dados: 5
Autores: Le Hir, Pierre; Duchene, C.; Merel, A; De Nadaillac, G.; Merceron, Michel; Breton, Marguerite.
The rate of flow of the fresh water releases at the Arzal Dam into the Vilaine is likely to influence the haline structure of Vilaine Bay. In order to determine the rate of flow that causes a minimum downstream stratification, a vertical two-dimensional mathematical modelling of the Vilaine's estuary was undertaken. We obtain very similar stratification flows for different fresh water release scenarios, in spite of the rather different desalinisations and currents.
Tipo: Text
Palavras-chave: Water release; Stratification; Estuary; Numerical model; Vilaine; Rejet de barrage; Stratification; Estuaire; Modèle numérique; Vilaine.
Ano: 1986
URL: https://archimer.ifremer.fr/doc/1986/rapport-2654.pdf

Ocean response to meridional ekman transport in the Atlantic and implication for gravity missions - art. no. 2145
Provedor de dados: 5
Autores: Ganachaud, Alexandre; Mercier, Herle.
[1] Wind friction at the ocean surface introduces energetic variations in the net mass transport across the oceanic basins. To conserve mass, the whole water column adjusts rapidly, introducing a depth-independent perturbation in the pressure field. This signal is analyzed in a high resolution numerical model of the Atlantic Ocean. While the pressure perturbation cannot be extracted from the energetic sea surface height signals, it represents up to 90% of the bottom pressure signal when integrated across the Atlantic Ocean in the daily and monthly frequencies. This signal will be an important part of the signal measured by the GRACE (Gravity Recovery And Climate Experiment) mission.
Tipo: Text
Palavras-chave: Eckman transport; Numerical model; Pressure perturbation; Ocean surface.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/2002/publication-490.pdf

Vortex erosion in a shallow-water model
Provedor de dados: 5
Autores: Louazel, Stephanie; Hua, Bach-lien.
The purpose of this paper is to study the erosion of eddies by filamentation in a shallow-water model where both fast and slow components of the dynamics coexist. In presence of inertia-gravity waves this filamentation process is indeed found to be altered. However, the information required to analyze the filamentation process is shown to be entirely captured by the slow component of the flow and regions of filament ejection can be identified from a diagnostic criterion based on instantaneous slow quantities. This is illustrated numerically in a reduced gravity model for an initial elliptic vortex of distributed potential vorticity in presence of Poincare waves. (C) 2004 American Institute of Physics.
Tipo: Text
Palavras-chave: Numerical model; Filamentation; Vorticity; Eddies.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/2004/publication-711.pdf

A model of the general circulation in the Persian Gulf and in the Strait of Hormuz: Intraseasonal to interannual variability
Provedor de dados: 5
Autores: Pous, Stephane; Lazure, Pascal; Carton, Xavier.
Previous studies modeling the circulation and thermohaline structure in the Persian Gulf have suggested that interannual variability and vertical mixing processes could explain the model biases when compared to the few observations available. Here, a realistic, interannual, high-resolution model of the Persian Gulf is presented, validated against observations and then used to describe the intraseasonal to interannual variability in the circulation, water mass formation and exchange through the Strait of Hormuz. Sensitivity experiments to model settings, in particular vertical mixing parameterizations, have been performed in order to have the best comparison with all available observations. Main circulation and water mass characteristics correspond well to...
Tipo: Text
Palavras-chave: Persian Gulf; Strait of Hormuz; Numerical model; Hydrology; Currents; Interannual variability.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00244/35563/35324.pdf

On the effect of tidal flats on the hydrodynamics of the Tagus estuary
Provedor de dados: 5
Autores: Fortunato, Ab; Oliveira, A; Baptista, Am.
The effects of tidal flats on the hydrodynamics of the Tagus estuary are analysed using an accurate high-resolution shallow water model, supported by field data. Tidal flats act mainly as energy filters, rather than sinks, transferring energy from astronomic to non-linear frequencies. They also play a major role in determining the strong resonance mode that amplifies semi-diurnal constituents. We show that the upper estuary, with extensive tidal flats, has an increasing accretion rate. This "filling-up" results from a positive feedback between sediment deposition and the hydrodynamics: accretion in the upper estuary lengthens the duration of ebbs, decreasing sediment flushing and further increasing accretion.
Tipo: Text
Palavras-chave: Estran; Propagation de marée; Modèle numérique; Estuaire du Tage; Tidal flats; Tidal propagation; Numerical model; Tagus estuary.
Ano: 1999
URL: http://archimer.ifremer.fr/doc/00325/43626/43257.pdf

Numerical modelling of equilibrium and evolving lightweight sediment laboratory beach profiles.
Provedor de dados: 5
Autores: Dubarbier, Benjamin; Castelle, Bruno; Marieu, Vincent; Michallet, Hervé; Grasso, Florent; Ruessink, Gerben.
The recent advances of numerical beach profile models allowed the simulation of on/offshore sandbar migrations on timescales of weeks to months with fair success. These models were systematically applied to natural, persistently evolving, beaches. In this contribution, we apply our model to small-scale laboratory experiments for which coarse and lightweight sediment is used to satisfy the laws of similitude in the flume. Such experiments can result in equilibrium beach profiles and provide detailed information on the respective role of undertow and wave nonlinearities on sediment transport and the resulting cross-shore sandbar migration. Here we first apply the coupled, wave-averaged, cross-shore waves-currents-bathymetric evolution model 1DBeach to an...
Tipo: Text
Palavras-chave: Beach profile; Numerical model; Physical modelling; Equilibrium profile; Sandbar migration.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00180/29089/27503.pdf

Vortex merger in surface quasi-geostrophy
Provedor de dados: 5
Autores: Carton, Xavier; Ciani, Daniele; Verron, J.; Reinaud, J.; Sokolovskiy, M.
The merger of two identical surface temperature vortices is studied in the surface quasi-geostrophic model. The motivation for this study is the observation of the merger of submesoscale vortices in the ocean. Firstly, the interaction between two point vortices, in the absence or in the presence of an external deformation field, is investigated. The rotation rate of the vortices, their stationary positions and the stability of these positions are determined. Then, a numerical model provides the steady states of two finite-area, constant-temperature, vortices. Such states are less deformed than their counterparts in two-dimensional incompressible flows. Finally, numerical simulations of the nonlinear surface quasi-geostrophic equations are used to...
Tipo: Text
Palavras-chave: Shear/strain flow; Steady states; Vortex merger; Numerical model; Surface quasi-geostrophy; Critical distance.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00323/43460/42864.pdf

How ocean waves rock the Earth: two mechanisms explain microseisms with periods 3 to 300 s
Provedor de dados: 5
Autores: Ardhuin, Fabrice; Gualtieri, Lucia; Stutzmann, Eleonore.
Microseismic activity, recorded everywhere on Earth, is largely due to ocean waves. Recent progress has clearly identified sources of microseisms in the most energetic band, with periods from 3 to 10 s. In contrast, the generation of longer-period microseisms has been strongly debated. Two mechanisms have been proposed to explain seismic wave generation: a primary mechanism, by which ocean waves propagating over bottom slopes generate seismic waves, and a secondary mechanism which relies on the nonlinear interaction of ocean waves. Here we show that the primary mechanism explains the average power, frequency distribution, and most of the variability in signals recorded by vertical seismometers, for seismic periods ranging from 13 to 300 s. The secondary...
Tipo: Text
Palavras-chave: Hum; Infragravity waves; Numerical model; Microseisms.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00251/36219/34769.pdf

Remaniements sédimentaires superficiels sur l'estran occidental de la baie du Mont Saint-Michel
Provedor de dados: 5
Autores: Bonnot-courtois, C; Bassoullet, Philippe; Tessier, B; Cayocca, Florence; Le Hir, Pierre; Baltzer, A.
In order to define and quantify the rhythm and amplitude of the processes of erosion and sedimentation on broad tidal flats, in situ measurements of sediment elevation have been performed in the western part of the Mont-Saint-Michel bay. The amplitude of reworking is generally low (&lt; ± 5 cm), and variable from west to east. The wind influence on tidal currents and surficial reworking emphasizes erosion phases rapidly followed by accretion of similar amplitude on the whole tidal flat. A numerical model for hydrodynamics and sediment transport is applied to Mont Saint Michel Bay, where ecological concerns are related to sediment transfers.
Tipo: Text
Palavras-chave: Sediment transport; Numerical model; Erosion sedimentation budget; "In situ" measurements; Tidal sandy mud flat; Transport sédimentaire; Modèle numérique; Bilan érosion sédimentation; Mesures in situ; Estran sablo vaseux.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-6279.pdf

Finite element model for the assessment of the mesh resistance to opening of fishing nets
Provedor de dados: 5
Autores: Morvan, Barthelemy; Priour, Daniel; Guede, Zakoua; Bles, G.
The evaluation of the mesh resistance to opening of fishing nets is an important issue in assessing the selectivity of trawls by numerical methods. Sala et al. (2007) proposed a method using a relatively expensive experimental device ensuring the 2D deformation of net sample. De la Prada and Gonzales (2015) proposed a simple uni-axial experimental set-up, which stretches a sample in the transverse direction of the meshes while leaving free its deformation in the normal direction. Both authors (Sala and De la Prada) assumed that the deformation is uniform in the sample. The present study aims at developing a finite element model taking into account the mesh resistance to opening of nets, allowing the simulation of non-uniform deformation. Mechanical...
Tipo: Text
Palavras-chave: Netting; Mesh resistance to opening; Bending stiffness; Experiment; Numerical model.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00347/45813/49043.pdf

The 1867 Virgin Island tsunami: observations and modeling
Provedor de dados: 5
Autores: Zahibo, N; Pelinovsky, E; Yalciner, A; Kurkin, A; Koselkov, A; Zaitsev, A.
The 1867 Virgin Island tsunami was of a great effect for the Caribbean Islands. A maximal tsunami height of 10 m was recorded for two coastal locations (Deshayes and St. Rose) in Guadeloupe. The historical data of this event for the Caribbean Sea are discussed. The modeling of the 1867 tsunami is performed in the framework of the nonlinear shallow-water theory. The four different orientations of the tsunami source in the Anegada Passage are examined. The directivity of the tsunami wave in the Caribbean is investigated. The time histories of water surface fluctuations are calculated for several coastal locations on the coasts of the Caribbean Sea. Results of the numerical simulations are in reasonable agreement with data of observations.
Tipo: Text
Palavras-chave: Tsunami; Théorie en eau peu profonde; Modèle numérique; Mer des Caraïbes; Tsunami; Shallow-water theory; Numerical model; Caribbean Sea.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/00321/43252/42983.pdf

Etude des échanges entre l’Océan Arctique et l’Atlantique Nord : Origine, Variabilité et Impact sur les mers Nordiques
Provedor de dados: 5
Autores: Lique, Camille.
While perhaps the most obvious, ice retreat is just one aspect of a changing Arctic system. The Arctic Ocean is also undergoing unprecedented modifications, that mostly affect its heat and freshwater budgets. As the signal of Arctic change is expected to have its major climatic impact by reaching south the subarctic seas, on either side of Greenland, to modulate the Atlantic thermohaline circulation, the objective of this thesis is to investigate the variability of the exports of volume, heat, freshwater and sea-ice from the Arctic Ocean to the North Atlantic.  First, a realistic simulation from 1958 to 2002 run with a global ocean/sea-ice model is used to investigate some aspects of the variability of the Arctic freshwater budget, trying to understand...
Tipo: Text
Palavras-chave: Océan Arctique; Bilan d'eau douce; Flux d'eau douce; Glace de mer; Modèle numérique - Analyse Lagrangienne - Forçages atmosphériques; Arctic Ocean; Freshwater budget; Freshwater flux; Sea ice; Numerical model; Lagrangian analysis; Atmospheric forcing.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00015/12597/9474.pdf

Modelling cyclonic eddies in the Delagoa Bight region
Provedor de dados: 5
Autores: Cossa, O.; Pous, Stephane; Penven, P.; Capet, X; Reason, C. J. C.
The objective of this study is to document and shed light on the circulation around the Delagoa Bight region in the southern Mozambique Channel using a realistic modelling approach. A simulation including mesoscale forcings at the boundaries of our regional configuration succeeds in reproducing the general circulation in the region as well as the existence of a semi-permanent cyclonic eddy, whose existence is attested by in situ measurements in the Bight. Characterised by a persistent local minimum in SSH located around 26 °S—34 °E, this cyclonic eddy termed herein the Delagoa Bight lee eddy occurs about 25% of the time with no clear seasonal preference. Poleward moving cyclones, mostly generated further north, occur another 25% of the time in the Bight...
Tipo: Text
Palavras-chave: Delagoa Bight; Cyclonic lee eddy; Coastal countercurrent; Numerical model; Mozambique Channel; Shelf processes.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00318/42941/42449.pdf

The effect of the bottom boundary layer on trawl behaviour
Provedor de dados: 5
Autores: De La Prada, Amelia; Priour, Daniel.
Thirty-seven hauls of a bottom trawl were carried out, as part of a national French project. These sea trials were undertaken in an area with strong currents: up to 1 knot. The measurements at sea of the bottom bridle’s tension show a clear effect of the current. Although the water speed relative to the trawl is constant, when the boat tows with current, the bottom bridle’s tension increases, and when the boat tows against the current, the bottom bridle’s tension decreases. The mean bottom bridle tension is 7840 N and increases with a slope of 1197 N for each m/s of current. The current has almost no effect on the top bridle’s tension: for a mean value of approximately 9810 N, the increment is 106 N for each m/s of current. The modelling of the trawl gear...
Tipo: Text
Palavras-chave: Trawl; Data; Numerical model; Bridle tension; Bottom boundary layer; Water speed.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00266/37710/35800.pdf

Projet EMACOP : caractérisation des vagues et du potentiel houlomoteur des sites d’Esquibien et de Saint-Guénolé par simulation numérique
Provedor de dados: 5
Autores: Michard, Bertrand; Cosquer, Emmanuel; Mallegol, Antoine; Coignard, Jonathan; Filipot, Jean-françois; Kpogo Nuwoklo, Komlan; Olagnon, Michel; Sergent, Philippe.
The French research EMACOP project aims at characterising wave power nearby onshore structures. This paper presents the application of the non-hydrostatic wave-flow model SWASH to wave propagation and transformation on two hot spots in Brittany. The numerical simulations were performed for dominant wave conditions and three tide levels. The results of wave simulations allow us to characterise wave energy resources and define Wave Energy Converters (WEC)'s promising positions on both sites.
Tipo: Text
Palavras-chave: Potentiel houlomoteur; Modèle numérique; SWASH; Bretagne; EMACOP; Wave power; Resources; Numerical model; SWASH; Brittany; EMACOP.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00348/45927/45620.pdf

The Eddy Experiment: GNSS-R speculometry for directional sea-roughness retrieval from low altitude aircraft - art. no. L21307
Provedor de dados: 5
Autores: Germain, O; Ruffini, Giulio; Soulat, F; Caparrini, M; Chapron, Bertrand; Silvestrin, P.
We report the retrieval of sea surface directional mean square slope from Global Navigation Satellite System Reflections (GNSS-R) Delay-Doppler-Map (DDM) data collected during an experimental flight at 1 km altitude. We emphasize the utilization of the entire DDM to more precisely infer ocean roughness directional parameters, and argue that the DDM exhibits the impact of both roughness and scatterer velocity. Obtained estimates are analyzed and compared with Jason-1 measurements, ECMWF numerical weather model outputs and optical data.
Tipo: Text
Palavras-chave: Numerical model; Velocity; Sea surface roughness; Eddies; Delay Doppler Map; Remote sensing; Oceanography.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/2004/publication-749.pdf

Caractérisation expérimentale et numérique du comportement hydrodynamique d’une hydrolienne à membrane ondulante
Provedor de dados: 5
Autores: Trasch, Martin.
The thesis presented in this document deals with the caracterisation of the behaviour of an undulating membrane tidal energy converter. This kind of device uses the flutter instabilities occurring between a semi-rigid pre-strained membrane and a fluid flow in order to convert the sea currents energy. Above a certain critical flow speed, the structure ondulates, thus activating the linear converters fixed on it. In order to study this system, an experimental model is developped and tested in a flume tank. The power conversion system is simulated by hydraulic dampers. The membrane’s dynamics is analysed in many configurations through trajectory and force measurements, and leads to a parametric study. More realistic flow conditions are also studied, such as...
Tipo: Text
Palavras-chave: Énergies marines renouvelables; Hydrolienne; Interaction fluidestructure; Instabilité de flottement; Essais expérimentaux; Particle Image Velocimetry; Modélisation numérique; Méthode vortex; Éléments finis; Corotationnel; Houle; Effet d’échelle; Marine renewable energy; Tidal energy converter; Power takeoff; Fluid-structure interaction; Flutter instability; Experimental trial; Particle Image Velocimetry; Numerical model; Vortex method; Corotational finite elements; Surface wave; Scale effect.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00490/60185/63527.pdf

Inverse identification of the bending stiffness of a braided polyethylene twine subject to large deformation: application to the identification of the mesh opening rigidity of fishing nets.
Provedor de dados: 5
Autores: Morvan, Barthelemy; Bles, G; Dumergue, Nicolas; Priour, Daniel.
The evaluation of the mesh opening stiffness of fishing nets is an important issue in assessing the selectivity of trawls. It appeared that a larger bending rigidity of twines decreases the mesh opening and could reduce the escapement of fish. Nevertheless, netting structure is complex. A netting is made up of braided twines made of polyethylene or polyamide. These twines are tied with non-symmetrical knots. Thus, these assemblies develop contact-friction interactions. Moreover, the netting can be subject to large deformation. In this study, we investigate the responses of netting samples to different types of solicitations. Samples are loaded and unloaded with creep and relaxation stages, with different boundary conditions. Then, two models have been...
Tipo: Text
Palavras-chave: Numerical model; Experiments; Braided twine; Mesh opening rigidity; Large deformation.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00348/45899/45581.pdf

Three-dimensional numerical model study of the residual current in the South China Sea
Provedor de dados: 5
Autores: Cai, Sq; Huang, Qz; Long, Xm.
A three-dimensional baroclinic shelf sea model is employed to simulate the tidal and non-tidal residual current in the South China Sea. The four most significant constituents, M-2, S-2, K-1 and O-1, are included in the experiments with tidal effect. At most stations, the computed harmonic constants agree well with the observed ones. The circulations of the South China Sea in summer (August) and winter (December) are mainly discussed. It is shown that the barotropic tidal residual current is too weak to affect the South China Sea circulation, whilst the contribution of the baroclinic tidal residual current to the South China Sea circulation would be important in the continental shelf sea areas, especially in the Gulf of Thailand and Gulf of Tonkin. In the...
Tipo: Text
Palavras-chave: Marée; Courant résiduel; Modèle numérique; Mer de Chine du Sud; Tides; Tidal current; Residual current; Numerical model; South China Sea.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/00321/43251/42982.pdf

Modeling and forecasting the "weather of the ocean" at the mesoscale
Provedor de dados: 5
Autores: Treguier, Anne-marie; Chassignet, Eric P.; Le Boyer, Arnaud; Pinardi, Nadia.
We present a historical perspective on ocean mesoscale variability and turbulence, from the physical basis and the first numerical models to recent simulations and forecasts. In the mesoscale range (typically, spatial scales of 100 km and time scales of a month), nonlinearity, and energy cascades were well understood in the 1970s, but the emergence of coherent vortices took place much later. New challenges have arisen with the exploration of the submesoscale regime, where frontal dynamics play a key role and the range of flow instabilities is wider than in the quasi-geostrophic regime. Special focus is placed on the interaction of mesoscale turbulence with the continental slopes. The contrast between the variability on the western and eastern boundaries of...
Tipo: Text
Palavras-chave: Numerical model; Ocean forecast; Ocean mesoscale turbulence.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00410/52106/52939.pdf

A Lagrangian analysis of the Indian-Atlantic interocean exchange in a regional model - art. no. L14611
Provedor de dados: 5
Autores: Doglioli, Andrea; Veneziani, M; Blanke, Bruno; Speich, Sabrina; Griffa, A.
We present a new numerical Lagrangian technique based on the coupling of transport computation with spin analysis of trajectories. This method was applied to results from a high-resolution numerical model of the oceanic region around South Africa. We estimated an Indian-Atlantic leakage of about 14 Sv. In the western Cape Basin, approximately 30% of this transport is due to trapping eddies with a ratio between cyclones and anticyclones transport of 1.3. These findings are briefly discussed with respect to recent observations of the highly nonlinear regime found in this area of the Cape Basin.
Tipo: Text
Palavras-chave: Anticyclones transport; Cyclones transport; The Indian Atlantic interocean exchange; South Africa; Numerical model.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-1847.pdf

Tasman leakage: A new route in the global ocean conveyor belt - art. no. 1416
Provedor de dados: 5
Autores: Speich, Sabrina; Blanke, Bruno; De Vries, Pedro; Drijfhout, Sybren; Doos, Kristofer; Ganachaud, Alexandre; Marsh, Robert.
[1] The existence of a new route that draws relatively cold waters from the Pacific Ocean to the North Atlantic via the Tasman outflow is presented. The new route materialises with comparable magnitude and characteristics in three independent numerical realisations of the global ocean circulation. Its realism is supported by hydrographic data interpolated via an inverse model. The "Tasman leakage'' constitutes a sizeable component of the upper branch of the global conveyor belt and represents an extension to the prevailing views that hitherto emphasised the routes via the Drake Passage and the Indonesian Throughflow [Gordon, 1986].
Tipo: Text
Palavras-chave: Numerical model; Ocean circulation.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/2002/publication-771.pdf

Modelling for anchovy recruitment studies in the Gulf of Lions (Western Mediterranean Sea)
Provedor de dados: 5
Autores: Nicolle, Amandine; Garreau, Pierre; Liorzou, Bernard.
Anchovy (Engraulis encrasicolus) is an important commercial species and one of the most abundant pelagic fish in the Gulf of Lions and the Catalan Sea. The factors influencing its recruitment are crucial to fisheries and ecological research. Among those factors transport of larvae by hydrodynamics (currents) is important because it determines whether the organisms can reach areas favourable to recruitment or are dispersed. Therefore, the first step in anchovy recruitment modelling is to simulate North-western Mediterranean Sea circulation. Several years (2001-2008) of hydrodynamics were simulated with the MARS-3D code. The resulting simulated currents and salinity are used by Lagrangian tool, Ichthyop, to transport anchovy eggs and larvae to the Western...
Tipo: Text
Palavras-chave: Diel vertical migration; Lagrangian transport; Gulf of Lions; Numerical model; Mediterranean Sea; Anchovy.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-7394.pdf

Shelf-edge jet currents in the southern Benguela: a modelling approach
Provedor de dados: 5
Autores: Veitch, Jennifer; Hermes, Juliet; Lamont, Tarron; Penven, Pierrick; Dufois, Francois.
The dynamics and seasonal variability of jet currents on the southern Benguela shelf-edge are investigated using a climatologically forced ROMS model. The jet is primarily forced by the intense horizontal gradients that exist across the southern Benguela shelf. These gradients are set up by nearshore cooling via the strongly seasonal upwelling regime and variable offshore warming by the advection of Agulhas waters. While the nearshore cooling is prevalent only during the spring and summer upwelling season, the offshore warming exists throughout the year. As a result intensified geostrophically adjusted currents exist throughout the year, particularly off the Cape Peninsula and Cape Columbine. However, the distinct shelf-edge jet features are most intense...
Tipo: Text
Palavras-chave: Southern Benguela; Shelf-edge jet; Numerical model.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00403/51401/51976.pdf

Modelling larval dispersal of the king scallop (Pecten maximus) in the English Channel: examples from the bay of Saint-Brieuc and the bay of Seine
Provedor de dados: 5
Autores: Nicolle, Amandine; Dumas, Franck; Foveau, Aurelie; Foucher, Eric; Thiebaut, Eric.
The king scallop (Pecten maximus) is one of the most important benthic species of the English Channel as it constitutes the first fishery in terms of landings in this area. To support strategies of spatial fishery management, we develop a high-resolution biophysical model to study scallop dispersal in two bays along the French coasts of the English Channel (i.e. the bay of Saint-Brieuc and the bay of Seine) and to quantify the relative roles of local hydrodynamic processes, temperature-dependent planktonic larval duration (PLD) and active swimming behaviour (SB). The two bays are chosen for three reasons: (1) the distribution of the scallop stocks in these areas is well known from annual scallop stock surveys, (2) these two bays harbour important fisheries...
Tipo: Text
Palavras-chave: King scallop; English Channel; Numerical model; Lagrangian transport; Planktonic larval duration; Swimming behaviour.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00146/25705/26396.pdf

A numerical study of the generation and propagation of internal solitary waves in the Luzon Strait
Provedor de dados: 5
Autores: Cai, Sq; Long, Xm; Gan, Zj.
A new composite model, which consists of a generation model of the internal tides and a regularized long wave propagation model, is presented to study the generation and evolution of internal solitary waves in the sill strait. Internal bores in the sill strait are first simulated by the generation model. and then the internal tidal field outside of the sill region is given as input for the propagation model. Numerical experiments are carried out to Study the imposing tide, depth profile. channel width and shoaling effect, etc., on the generation and evolution of internal solitary waves. It is shown that only when the amplitude of internal tide at the forcing boundary of the propagation model is large enough that a train of internal solitary waves would be...
Tipo: Text
Palavras-chave: Marée interne; Modèle numérique de soliton; Mer de Chine; Internal wave; Soliton; Numerical model; South China Sea.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/00322/43319/42935.pdf

Seasonal fluctuations in the deep central equatorial Atlantic Ocean: a data-model comparison
Provedor de dados: 5
Autores: Thierry, Virginie; Mercier, Herle; Treguier, Anne-marie.
Low-frequency current fluctuations in the deep central equatorial Atlantic are analyzed using current meter measurements recorded from November 1992 to November 1994. Current meters were located at about 14 degrees W of longitude and 1 degrees of latitude on both sides of the equator between 1,700 m depth and the ocean bottom. At all sampling depths, the velocity fluctuations are dominantly zonal and symmetrical with respect to the equator. At 1,700 and 2,000 m, the flow is dominated by annual period fluctuations, at 3,000 m, the velocity field amplitude presents a minimum, and at 3,750 and 3,950 m, the flow is modulated by annual and semiannual period variability. The annual signal exhibits an apparent upward phase propagation. When considering the phase...
Tipo: Text
Palavras-chave: Vertical propagation; Equatorial waves; Numerical model; Current meter data; Equatorial Atlantic Ocean.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-2257.pdf

Agulhas eddy fluxes in a 1/6 degrees Atlantic model
Provedor de dados: 5
Autores: Treguier, Anne-marie; Boebel, O; Barnier, B; Madec, G.
A 1/6degrees resolution primitive equation model of the Atlantic circulation is analyzed in the Agulhas region. The model has a realistic level of eddy kinetic energy, and produces anticyclonic Agulhas rings as well as cyclonic structures. In the model as well as in the data, ring trajectories undergo a transition between a turbulent character in the Cape Basin and a steady propagation in the rest of the South Atlantic. The topography of the Walvis Ridge does not seem to play a part in generating this contrast in the model. The model shows that cyclones are primarily generated from the negative shear vorticity side of the Agulhas Current as it leaves the coast, and they are most of the time paired with anticyclones in dipolar or tripolar structures....
Tipo: Text
Palavras-chave: South Africa; South Atlantic Ocean; Numerical model; Ocean currents; Oceanic eddies; Eddy flux.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/2003/publication-453.pdf

Numerical model validation for mooring systems: Method and application for wave energy converters
Provedor de dados: 5
Autores: Harnois, V.; Weller, Sam D.; Johanning, L.; Thies, P. R.; Le Boulluec, Marc; Le Roux, Dominique; Soule, Veronique; Ohana, Jeremy.
The design of wave energy mooring systems is challenging: overdesign incurs a significant cost penalty, underdesign may lead to a premature failure and incorrect design could reduce the power production. Consequently, compliant mooring systems are being developed for wave energy applications. This paper presents tank test results for a scale model of the buoy and mooring used at the SouthWest Mooring Test Facility (SWMTF), an offshore facility developed to conduct long-term sea trials for wave energy device moorings. A compliant three leg catenary mooring system using Nylon ropes in the water column is investigated. Preliminary static, quasi-static, decay, regular and irregular wave tests were conducted on the 1:5 scale model, using the Ifremer basin in...
Tipo: Text
Palavras-chave: Wave energy converter; Tank tests; Numerical model; Highly dynamic mooring system; Fibre rope.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00233/34375/35785.pdf

Seasonal cycle of the salinity barrier layer revealed in the northeastern Gulf of Guinea
Provedor de dados: 5
Autores: Dossa, A. N.; Da-allada, C. Y.; Herbert, G; Bourles, Bernard.
The region located in the far northeast of the Gulf of Guinea (NEGG), eastern tropical Atlantic, remains poorly documented due to a lack of available in situ ocean data. Heavy rainfall and intense river discharges observed in this region induce a strong salinity stratification that may have a significant impact on the mixed layer depth and on sea surface temperatures, through the so-called barrier-layer effect. By using recent in situ data and climatological outputs from a numerical simulation, we reveal the existence of a barrier layer in the NEGG and describe its seasonal occurrence. In the NEGG, the barrier layer limits the mixed layer depth. From January to March, significant values for the barrier-layer thickness are observed mostly due to the...
Tipo: Text
Palavras-chave: Mixed layer depth; Niger River discharge; Numerical model; Oceanography; Sea surface salinity; Tropical Atlantic; Vertical stratification.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00509/62103/66273.pdf

Can a Warmer Climate Save Northern Agriculture?
Provedor de dados: 31
Autores: Gaasland,   Ivar.
Agriculture at high latitudes is expected to be a main beneficiary of a man-made climate change. A numerical model, using Norway as a case, is employed to analyze the impacts of a warmer climate on northern agriculture. The computations indicate that the current degree of self-sufficiency can be achieved with less budget support and higher economic welfare. However, it may be argued that environmental goods, such as landscape and biodiversity preservation, and rural settlement, are more important than self-sufficiency for northern agriculture. It is demonstrated that, in that case, welfare gains are substantially lower, and can even be negative.
Tipo: Conference Paper or Presentation
Palavras-chave: Climate change; Northern agriculture; Environmental goods; Numerical model; Environmental Economics and Policy; Resource /Energy Economics and Policy; L52; Q18; Q24.
Ano: 2005
URL: http://purl.umn.edu/24551

Multifunctionality of Agriculture: An Inquiry Into the Complementarity Between Landscape Preservation and Food Security
Provedor de dados: 31
Autores: Brunstad,   Rolf Jens; Gaasland,   Ivar; Vardal,   Erling.
Without support, the levels of agricultural public goods will fall short of the demand in high cost countries like Norway, Finland and Iceland. However, as demonstrated in this paper using Norway as a case, the current support and agricultural activity is far out of proportions from a public goods perspective. Model simulations show that at most 40% of the current support level can be defended by the public good argument. Furthermore, the present support, stimulating high production levels, is badly targeted at the public goods in question. Since agricultural land is a major component of both food security and landscape preservation, thus giving rise to a high degree of cost complementarities between the two public goods, it would be more efficient to...
Tipo: Conference Paper or Presentation
Palavras-chave: Food security; Landscape preservation; Public goods; Agricultural policy; Numerical model; Food Security and Poverty; Land Economics/Use.
Ano: 2005
URL: http://purl.umn.edu/24470

Numerical modeling of the effect of variation of boundary conditions on vadose zone hydraulic properties
Provedor de dados: 90
Autores: Leão,Tairone Paiva; Gentry,Randall.
An accurate estimation of hydraulic fluxes in the vadose zone is essential for the prediction of water, nutrient and contaminant transport in natural systems. The objective of this study was to simulate the effect of variation of boundary conditions on the estimation of hydraulic properties (i.e. water content, effective unsaturated hydraulic conductivity and hydraulic flux) in a one-dimensional unsaturated flow model domain. Unsaturated one-dimensional vertical water flow was simulated in a pure phase clay loam profile and in clay loam interlayered with silt loam distributed according to the third iteration of the Cantor Bar fractal object Simulations were performed using the numerical model Hydrus 1D. The upper and lower pressure heads were varied around...
Tipo: Info:eu-repo/semantics/report
Palavras-chave: Numerical model; Hydrus 1D; Uncertainty; Boundary conditions; Hydraulic conductivity; Soil physics.
Ano: 2011
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832011000100025