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| Registros recuperados: 99 | |
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| Lazure, Pascal; Salomon, Jean-claude. |
| The marine circulation between Quiberon and Noirmoutier is due to the combined effects of the tides, winds and density circulation induced by the discharges of the Vilaine and Loire rivers. These effects have been studied with two mathematical models, a two-dimensional (vertically integrated) one and a three-dimensional one. The tide has been shown to be the most important phenomenon at short time scale. Its effects are locally variable mainly because of topographic control. The tidal influence decreases significantly at long time scale and the residual circulation depends mainly on meteorological and hydrological conditions. The wind-induced circulation is mostly three-dimensional and appears locally to be the main dynamic process. During high flood, the... |
| Tipo: Text |
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| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/00245/35578/34111.pdf |
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| Lazure, Pascal; Salomon, Jean-claude. |
| The hydrodynamics of coastal zones often reflect the combined action of tides, winds and density differences. Usual two-dimensional numerical models are only partly suited to the study of such mechanisms. A set of two 2-D and 3-D numerical models is described here. Its main characteristics are: an automatic coupling, a specific procedure for shoaling banks, a reduced vertical coordinate system, and a resolution by finite differences. As an example, the complete set is applied to the region of the Loire and Vilaine estuaries in South Brittany (France). Results prove to be coherent with experimental data and enhance our knowledge of the local hydrodynamics. |
| Tipo: Text |
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| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/00101/21248/18862.pdf |
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| Tartinville, B; Deleersnijder, E; Lazure, Pascal; Proctor, R; Ruddick, Kg; Uittenbogaard, Re. |
| Several coastal ocean models have been used to compute the circulation on the Northwest European Continental Shelf. Five of them, developed within the European Union, are compared in the scope of an idealised three-dimensional test case, dealing with the geostrophic adjustment of a freshwater cylinder. As the central eddy adjusts, unstable baroclinic vortices start to grow. All the models are able to produce such unstable vortices. However, two of them produce an order-two instability, which is in accordance with a previous laboratory experiment, while the others exhibit an order-four instability. Using a simple scaling analysis, it is seen that the azimuthal wavenumber depends on the ratio of the kinetic energy to the available potential energy. It... |
| Tipo: Text |
Palavras-chave: Model intercomparison; Advection; Baroclinic instability; Geostrophic balance. |
| Ano: 1998 |
URL: http://archimer.ifremer.fr/doc/00448/55938/57485.pdf |
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| Allain, Gwenhael; Petitgas, Pierre; Lazure, Pascal. |
| Variability in anchovy recruitment in Biscay is temptatively explained using variables from the stock and from the environment during the ichtyoplankton phase. Anchovy recruitment depends on many different processes : weight of adults and proportion of multiple spawners (age 2), river discharges, upwelling events at the coast and at the shelf break. Meteorological variables (wind, rain, tempe rature ) are forcing effects on the sea but they are not the effective processes that govern the production in the sea. So they do not relate directly to the survival of larvae and to recruitment. In Biscay, many different physical processes are active and used by anchovy which spawns in different physical systems (river plumes, open ocean enrichment systems).... |
| Tipo: Text |
Palavras-chave: Bio-physical coupling; Recruitment; Anchovy; Hdrodynamics; Step by step regression. |
| Ano: 1999 |
URL: http://archimer.ifremer.fr/doc/00391/50190/50814.pdf |
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| Labry, Claire; Herbland, Alain; Delmas, Daniel; Laborde, P; Lazure, Pascal; Froidefond, J; Jegou, Anne-marie; Sautour, B. |
| Thermostratification and seasonal Light increase are generally considered the first causes of phytoplankton spring blooms in temperate waters. The objective of this study is to confirm the existence of winter phytoplankton blooms, responsible for the early exhaustion of phosphate, within the Gironde plume waters (southeast Bay of Biscay), and to understand what may initiate them so early. Two cruises, BIOMET 2 and BIOMET 3, were carried out respectively in early (8 to 21 January) and late winter 1998 (25 February to 11 March). An increase of phytoplankton biomass (chl a) between the 2 cruises and non-conservative nutrients observed in late winter confirm an early phytoplankton growth both in the Gironde plume and adjacent oceanic waters. Among factors that... |
| Tipo: Text |
Palavras-chave: Vertical attenuation coefficient; Halostratification; Light availability; Winter blooms. |
| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/2001/publication-810.pdf |
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| Barnier, Bernard; Lazure, Pascal. |
| L'océanographie physique côtière a pour objet d'observer, de comprendre et de prévoir le fonctionnement hydrodynamique du milieu côtier, avec comme enjeux, dans le cadre d'applications pluridisciplinaires, la pollution côtière, la gestion et la préservation des écosystèmes et des ressources halieutiques, la contribution des zones côtières aux puits de carbone, l'hydrodynamique sédimentaire et les échanges eau - sédiments. Contrairement à l'océanographie du large, l'océanographie côtière n'a pas bénéficié de grands programmes internationaux (tel que le World Ocean Circulation Experiment -WOCE) pour structurer ses activités de recherche dans le domaine de l'observation et de la modélisation au niveau national ou international. De plus, les problèmes traités... |
| Tipo: Text |
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| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/00020/13162/10212.pdf |
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| Loubersac, Lionel; Lazure, Pascal; Dumas, Franck; Le Roux, Jean-francois; Riou, Philippe; Foucher, Eric; Guillaumont, Brigitte. |
| On the morning of the 31th October 2000, the Italian chemical tanker “Ievoli Sun” sank in the central Channel. Her cargo presented a risk of contamination for the marine environment and nearby coastal environment. From the moment the sinking was announced, Ifremer decided to implement, in almost real time, tools to produce and communicate environmental data. This paper presents the solutions chosen to develop: - a Geographic Information System to prepare maps, - a series of simulations for dispersion at sea of dissolved products - a general information web site structure (see http://www.ifremer.fr/envlit/surveillance/ievoli.htm). This paper will go beyond technical presentations of methods, tools and results obtained to take a critical look at the site’s... |
| Tipo: Text |
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| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/00089/20054/17695.pdf |
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| Plus, Martin; Chapelle, Annie; Lazure, Pascal; Auby, Isabelle; Levavasseur, G; Verlaque, M; Belsher, Thomas; Deslous-paoli, Jean-marc; Zaldivar, J; Murray, C. |
| A three-dimensional model coupling physical and biological processes for the whole Than lagoon (Mediterranean coast of France) was developed in order to assess the relationships between macrophytes and the oxygen and nitrogen cycles. Ten species have been inserted as forcing variables in the model. Plankton dynamics, shellfish cultivation impact and mineralization of organic matter are also considered, as well as nutrient and oxygen exchanges between the sediment and the water column. Simulations with and without the macrophytes have shown that the system can be characterized as having a highly structured pattern involving lagoon nitrogen and oxygen cycles. This pattern is created by the combined influence of macrophytes, watershed and oyster farming.... |
| Tipo: Text |
Palavras-chave: Thau lagoon; Biogeochemical cycles; Ecological modelling; Macrophytes. |
| Ano: 2003 |
URL: https://archimer.ifremer.fr/doc/2003/publication-459.pdf |
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| Pous, Stephane; Carton, Xavier; Lazure, Pascal. |
| Hydrological, ADCP, and drifting buoy data obtained during the GOGP99 Experiment in October and early November 1999 are analyzed to describe the Persian Gulf Water (PGW) core and the regional circulation in the Gulf of Oman. The warm and salty PGW core flows out of the Strait of Hormuz heading southeastward unto (25degrees20'N, 57degreesE), approximately. From there, it cascades down the continental slope, veers southwestward, and joins the Omani coast near (24degrees50'N, 56degrees50'E) to form a slope current. This PGW current has then thermohaline maxima on isopycnal sigma(0) = 26.5, near 220 m depth. Its thermohaline characteristics decrease along its progression to Ra's al Hadd ( and then offshore into the Arabian Sea) but maintain a sharp contrast... |
| Tipo: Text |
Palavras-chave: Persian Gulf Water outflow; Regional circulation; Gulf of Oman. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/2004/publication-390.pdf |
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| Planque, Benjamin; Lazure, Pascal; Jegou, Anne-marie. |
| A complex set of hydrodynamical structures co-exist over the Bay of Biscay continental shelf. These structures, which can spread over a limited spatial range (10s of km) and last for periods ranging from days to months, influence the rates and nature of biological production. They need to be accurately described before the mechanisms linking hydrodynamics to production can be unraveled. Such description generally requires not only 3D observations of hydrological fields (temperature, salinity, density), but also a description of how these fields vary with time. This is hardly achievable with current means of field observation but can be mimicked by hydrodynamic model simulations. Using simulations from a 3D hydrodynamic model, we developed a methodology... |
| Tipo: Text |
Palavras-chave: Bay of Biscay; Hydrology; Hydrodynamic model; Spring; Typology. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/00000/10933/7575.pdf |
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| Pous, Stephane; Carton, Xavier; Lazure, Pascal. |
| In October and early November 1999, the GOGP99 experiment collected hydrological, currentmeter, tide recorder, thermistor and drifting buoy data near the Strait of Hormuz. Data analysis provides the water mass structure in the Strait: Persian Gulf Water (PGW) core is banked against the Omani coast, while Indian Ocean Surface Water (IOSW) lies near the Iranian coast. These water masses are most often covered by a homogeneous surface layer. Thermohaline characteristics of the PGW core decrease substantially downstream, from the Persian/Arabian Gulf to the Gulf of Oman. PGW and IOSW thermohaline characteristics and distribution also exhibit notable changes at periods shorter than a month as shown by repeated hydrological sections. The tidal signal measured... |
| Tipo: Text |
Palavras-chave: Oceanography; Hydrology; Hormuz. |
| Ano: 2004 |
URL: http://archimer.ifremer.fr/doc/2004/publication-389.pdf |
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| Puillat, Ingrid; Lazure, Pascal; Jegou, Anne-marie; Lampert, Luis; Miller, P. |
| A synthesis of 9 years of hydrographic measurements, acquired during approximately 25 cruises (1992-2000) on the French continental shelf of the Bay of Biscay, is presented. The main focus is upon salinity distribution, as it is little known in this area. The whole of the data set covers I I months of the year, with some sampling fields repeated several times a year, for multiple years. This time-series allows temperature and salinity distributions to be studied together with their seasonal, inter-annual and mesoscale variability. The seasonal trend in temperature can be described in three stages, which are in agreement with past studies. Thermal stratification occurs between May and mid-September in a layer similar to 50 m in thickness, whereas the... |
| Tipo: Text |
Palavras-chave: Upwelling; Cold pool; River plumes; Seasonal variability; Salinity; Hydrography. |
| Ano: 2004 |
URL: https://archimer.ifremer.fr/doc/2004/publication-779.pdf |
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| Registros recuperados: 99 | |
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