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| Registros recuperados: 99 | |
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| Puillat, Ingrid; Carlier, Antoine; Facq, Jean-valery; Rubio, Anna; Lazure, Pascal; Delauney, Laurent; Petihakis, George; Karlson, Bengt; Artigas, Felipe; Farcy, Patrick. |
| A key message of the JERICO-RI consortium (2014): “The complexity of the coastal ocean cannot be well understood if interconnection between physics, biogeochemistry and biology is not guaranteed. Such integration requires new technological developments allowing continuous monitoring of a larger set of parameters”. In agreement with this consideration, several new observing systems are developed, tested and deployed in the framework of the JERICO-NEXT H2020 project, amongst which a few of them will be presented as well as some preliminary results after the first deployments. Focus will be given on coastal transports and hydrology and on benthic biodiversity. In the first case, we will present a low cost 2D moored system dedicated to acquire vertical... |
| Tipo: Text |
Palavras-chave: JERICO; JERICO-NEXT; Coastal; Ocean Observing System (OOS); Harmonization. |
| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00437/54866/56359.pdf |
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| Lazure, Pascal. |
| The Bay of Biscay continental shelf is the site of a variety of physical processes, none of which are permanently dominant. The variability of the circulation from daily to interannual scales has been explored through both modelling and observation. Emphasis will be placed on one of the peculiarities of the Atlantic Plateau: the importance of river flows whose catchment areas represent half of the metropolitan territory. The mixing of these fresh waters with marine waters forms plumes that oscillate according to winds and general circulation. Increasingly refined modelling and a growing number of observations now make it possible to describe their fate and their extension as far as the English Channel. The general circulation on the shelf is weak and... |
| Tipo: Text |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00610/72176/70951.pdf |
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| Pous, Stephane; Carton, Xavier; Lazure, Pascal. |
| A shallow-water model, coupled with a three dimensional, hydrostatic ocean model, is used to study the wind induced circulation, and the Shatt-al-Arab river plume expansion, in the Persian Gulf. The models are used in an idealized configuration. The following results are obtained: 1) with northwesterly winds, a double gyre is formed: this gyre is cyclonic in the south and anticyclonic in the north. Southeastward currents flow along the Iranian and Arabian coast where the wind stress at the surface dominates the pressure gradient related to the free surface slope, and conversely in the deeper region of the Gulf; 2) In the eastern part of the Gulf, the cyclonic gyre intensifies, as observed and reported in the literature; 3) For northwesterly winds, the... |
| Tipo: Text |
Palavras-chave: Persian Gulf; Wind-Induced Circulation; Hydrodynamical Modeling. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00284/39521/38014.pdf |
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| Michel, Guillaume; Dupre, Stephanie; Baltzer, Agnes; Ehrhold, Axel; Imbert, Patrice; Pitel, Mathilde; Loubrieu, Benoit; Scalabrin, Carla; Lazure, Pascal; Marie, Louis; Geldof, Jean-baptiste; Deville, Eric. |
| Inactive and mostly elongated pockmarks of 100–200 m in dimension were recently discovered on the South Aquitaine Margin continental slope. They are distributed at water depths greater than 350 m in both interfluve and sediment-wave areas, and are strongly controlled by the sedimentary morphology and architecture. Water column and seafloor backscatter and sub-bottom profiler data do not exhibit present-day or past gas evidence, e.g., massive and continuous gas releases at the seabed and fossil methane-derived authigenic carbonates. It is thus proposed that the pockmarks originated from a shallow source and result from relatively recent and short-duration gas or water expulsion events. Former near-bottom currents may have contributed to the elongation of... |
| Tipo: Text |
Palavras-chave: Pockmark; Fluid; Seabed morphology; Aquitaine slope; GIS; Currents. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00413/52491/53279.pdf |
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| Lazure, Pascal; Pairaud, Ivane; Leizour, Stephane; Puillat, Ingrid. |
| Temperature distributions on continental shelves (depth < 150m) are often complex because the many physical processes induce very high spatial (both horizontal and vertical) and temporal variability. Temporal variability extends from a few tens of minutes for solitons (internal wave), a few hours for internal tide and inertial waves to a few days for upwelling or sub mesoscale dynamics. In the 1980s, satellites provided access to knowledge of surface temperatures. On the other hand, the internal temperature structure still requires in-situ measurements, which leads to the deployment of moorings at sea. These operations are often expensive and risky because the coastal zone is generally subject to intense activities such as fishing and sea conditions can... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00630/74245/73875.pdf |
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| Doré, Justine; Chaillou, Gwénaelle; Poitevin, Pierre; Lazure, Pascal; Poirier, André; Chauvaud, Laurent; Archambault, Philippe; Thébault, Julien. |
| Despite its major role as a global climate regulator, little is known about the recent evolution of the North Atlantic Ocean, especially prior to the fifties, principally because of the lack of long-term instrumental data. Moreover, the North Atlantic Ocean is undergoing rapid changes at the physical scale leading to modifications at the biological scale increasing interest to monitor the environment. The phytoplankton is the base of the ocean life and its perturbation can lead to further changes in the food chain. Recording its dynamics implies to observe both its spatial and temporal variations. This study brings forward the use of the Ba/Ca ratio from shells of the long-living bivalve Arctica islandica collected in the Northwestern Atlantic Ocean near... |
| Tipo: Text |
Palavras-chave: A. islandica; Ba/Ca; Master chronology; Cross-dating; Chlorophyll a; Northwestern Atlantic. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00607/71881/70576.pdf |
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| Poitevin, Pierre; Thebault, Julien; Schoene, Bernd R.; Jolivet, Aurelie; Lazure, Pascal; Chauvaud, Laurent. |
| The Atlantic surfclam (Spisula solidissima) is a commercially important species in North American waters, undergoing biological and ecological shifts. These are attributed, in part, to environmental modifications in its habitat and driven by climate change. Investigation of shell growth patterns, trace elements, and isotopic compositions require an examination of growth lines and increments preserved in biogenic carbonates. However, growth pattern analysis of S. solidissima is challenging due to multiple disturbance lines caused by environmental stress, erosion in umbonal shell regions, and constraints related to sample size and preparation techniques. The present study proposes an alternative method for describing chronology. First, we analyzed growth... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00444/55597/57229.pdf |
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| Farrell, Hazel; Gentien, Patrick; Fernand, Liam; Lazure, Pascal; Lunven, Michel; Youenou, Agnes; Reguera, Beatriz; Raine, Robin. |
| Investigations into the phytoplankton of the Bay of Biscay in July 2006 revealed an extensive bloom of an unidentified haptophyte species. High-resolution sampling techniques identified the region in the vicinity of the mouth of the Loire estuary as an area of high (106–107 cells l−1) cell densities of the haptophyte in a thin sub-surface layer. This organism dominated the phytoplankton population regionally. Measurements of the vertical distribution of horizontal shear showed that the population, located at ca. 20 m depth, was confined to a layer lying between two density discontinuities with high shear. Physical measurements indicated that the population was being advected southeastwards, along the coast. Seaward spreading of the population was also... |
| Tipo: Text |
Palavras-chave: Haptophyte; Bay of Biscay; Horizontal dispersal; Thin layers. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00160/27129/25327.pdf |
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| Esnaola, Ganix; Saenz, J.; Zorita, E.; Lazure, Pascal; Ganzedo, U.; Fontan, A.; Ibarra-berastegi, G.; Ezcurra, A.. |
| The coupled variability of the Sea Surface Temperature (SST) and atmosphere-ocean surface heat fluxes over the Bay of Biscay (Eastern North Atlantic) has been analyzed. Daily surface heat fluxes from different meteorological reanalyses are combined with a high resolution reconstructed satellite SST data set by means of Lagged Maximum Covariance Analysis (MCA). Lagged MCA is applied at different spatial scales. Its results are interpreted within the framework of Hasselmann's stochastic climate model. The surface heat-flux feedback on SST is confirmed to be generally negative. No clear relation is found between the first MCA expansion series and the leading Sea Level Pressure (SLP) patterns. However, a clear relation is found between the second expansion... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00088/19937/17605.pdf |
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| 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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| Reverdin, G.; Boutin, J.; Martin, N.; Lourenco, A.; Bouruet-aubertot, P.; Lavin, A.; Mader, J.; Blouch, P.; Rolland,; Gaillard, Fabienne; Lazure, Pascal. |
| The accuracy of temperature measurements from drifters is first examined for 16 drifters (manufactured either by Metocean Data Systems or by Pacific Gyre) deployed with two temperature sensors in the tropical or North Atlantic Ocean. One of these sensors is the SST thermistor commonly used on Surface Velocity Program (SVP) drifters since the late 1980s; whereas the other sensor is a platinum temperature probe associated with a Seabird conductivity cell. The authors find (for 19 separate deployments) an average positive offset of the SST thermistor measurements in 17 out of 19 cases, exceeding 0.1 degrees C in five instances. Among the five drifters that were at sea for a year or more, two present a large trend in this offset (0.10 degrees and -0.10 degrees... |
| Tipo: Text |
Palavras-chave: Temperature; Sea surface temperature; Instrumentation; Sensors. |
| Ano: 2010 |
URL: https://archimer.ifremer.fr/doc/00012/12327/9112.pdf |
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| Ben Ismail, Dhouha Kbaier; Lazure, Pascal; Puillat, Ingrid. |
| In marine sciences, many fields display high variability over a large range of spatial and temporal scales, from seconds to thus ousands of years. The longer and longer recorded time series, with an increasing sampling frequency, in this field are often nonlinear, nonstationary, multiscale and noisy. Their analysis faces new challenges and thus requires the implementation of adequate and specific methods. The objective of this paper is to highlight time series analysis methods already applied in econometrics, signal processing, health,etc. to the environmental marine domain, assess advantages and inconvenients and compare classical techniques with more recent ones. Temperature, turbidity and salinity are important quantities for ecosystem studies. The... |
| Tipo: Text |
Palavras-chave: Continuous wavelet transform; Cross-correlation; Empirical mode decomposition; Hilbert Huang Transform; Stationarity; Time dependent intrinsic correlation; Time series; Wavelets. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00324/43519/43050.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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| Gentien, Patrick; Lunven, Michel; Lazure, Pascal; Youenou, Agnes; Crassous, Marie-pierre. |
| Karenia mikimotoi is one of the most common red-tide dinoflagellates proliferating in the eastern North Atlantic and around Japan. Kills of marine fauna are associated with its blooms. In mixed water columns it migrates vertically, while in stratified water columns, the population remains confined within pycnocline layers. Wind events, increasing mixing and agitation initiate declines in its populations. This paper is focused on the formulation of mortality rate relative to shear rate. Autotoxicity is demonstrated by the use of a synthetic toxin. Bioconvection observed in cultures allows the establishment of a trade-off between phototropism, which leads to the local accumulation of cells, and their autotoxicity, which would prevent cell concentration. The... |
| Tipo: Text |
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| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/2007/publication-2436.pdf |
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| Batifoulier, Francois; Lazure, Pascal; Bonneton, Philippe. |
| Two hydrodynamic surveys based on acoustic Doppler current profiler (ADCP) and drift buoys measurements taken in summer 2008 and 2009 revealed poleward coastal jets of up to 32 cm s(-1) that lasted up to 22 d along the Aquitaine shelf in the southeastern area of the Bay of Biscay. A strong increase in bottom temperature was associated with these currents, up to 4 degrees C in 5 d at 54 m depth. These observations occurred after a few days of westerlies, cross-shore winds which were thought to have only a limited impact on longshore circulation. Here, the MARS3D hydrodynamic model was used with a schematic bathymetry of the southeastern area of the Bay of Biscay to reproduce and analyze these coastal jets. Simulations revealed that the triggering mechanism... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00074/18569/16123.pdf |
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| Registros recuperados: 99 | |
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