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| Registros recuperados: 45.096 | |
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| Huh, Ca; Ku, Tl. |
| Seawater samples collected in the northeast Pacific from 112 degrees 50'W to 126 degrees 36'W along a latitudinal band (21-25 degrees N) have been analysed for Ra-228 and Ra-226. Both nuclides exhibit their characteristic distributions. In the surface water, the exponential-like decrease of Ra-228 away from Baja California can be interpreted by horizontal water mixing with eddy diffusion coefficients (K-x) of 1 x 10(6) cm(2) s(-1) and 5 x 10(7) cm(2) s(-1) for scale lengths of 200 km and 1000 km, respectively. In the bottom waters, the decrease of Ra-228 away from bottom sediments can be modeled by vertical eddy diffusivities (K-z) of 15-30 cm(2) s(-1) except at one station (24 degrees 16.9' N, 115 degrees 8.9' W) where a value of 120 cm(2) s(-1) is... |
| Tipo: Text |
Palavras-chave: Radium 228; Radium 226; Diffusion turbulente; Nord-Est Pacifique; Radium-228; Radium-226; Eddy diffusion; Northeast Pacific. |
| Ano: 1998 |
URL: http://archimer.ifremer.fr/doc/00325/43656/43218.pdf |
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| Huret, Martin; Petitgas, Pierre; Struski, Caroline; Leger, Fabien; Sourisseau, Marc; Lazure, Pascal. |
| Overexploitation and climate change are increasingly causing unanticipated changes in marine ecosystems, such as higher variability in fish recruitment and shifts in species distribution, pressing for developing fisheries oceanography. In the meantime, operational oceanography rapidly progresses and its products become easy to access to a large community, among them fisheries scientists. Multiyear oceanographic reanalyses (hindcasts) were identified has a priority product by the ICES WG on Operational Oceanographic Products for Fisheries and Environment (WGOOFE). We performed a 37 years hindcast (1972-2008) run with a coupled physical-biogeochemical model (ECO-MARS3D) over the Bay of Biscay, using realistic meteorological and run-off forcing. We first... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00023/13432/10442.pdf |
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| Mallat, Bachar; Germain, Gregory; Billard, Jean-yves; Gaurier, Benoit. |
| The bubble sweep-down phenomenon around oceanographic research vessels generates acoustic disturbances. A specific experimental protocol in a wave and current circulating tank is used to study this phenomenon around a 1/30 scale ship model in a configuration with current, waves and ship motions. 3D visualizations of the bubble clouds and Stereo-PIV (Particle Image Velocimetry) measurements results, both obtained in the bow vicinity of the ship model, are presented in this paper. The behaviour of the breaking wave with bubble generation is studied and the spatial evolution of the bubble clouds is investigated. It is demonstrated that the bubble cloud generation is mainly conditioned by the ascending vertical velocity of the flow near the bow. It is observed... |
| Tipo: Text |
Palavras-chave: Bubble sweep-down; Breaking wave; Bow wave; Fluid-structure interaction; Flume tank. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00453/56423/58534.pdf |
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| Ferron, Bruno. |
| The increasing number of oceanic observations calls for the use of synthetic methods to provide consistent analyses of the oceanic variability that will support a better understanding of the underlying mechanisms. In this study, a 1/3 degrees eddy-permitting model of the North Atlantic (from 20 degrees S to 70 degrees N) is combined with a 4D-variational method to estimate the oceanic state from altimeter observations. This resolution allows a better extraction of the physical content of altimeter data since the model spatial scales are more consistent with the data than coarser assimilation exercises because of a lower error in model representativity. Several strategies for the assimilation window are tested through twin experiments carried out under the... |
| Tipo: Text |
Palavras-chave: Ocean modelling; Data assimilation; Variational method; Meso-scale; Sea surface height; Heat transport; Meridional overturning. |
| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00044/15534/12956.pdf |
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| Frigola, J.; Canals, M.; Cacho, I.; Moreno, A.; Sierro, F. J.; Flores, J. A.; Berne, Serge; Jouet, Gwenael; Dennielou, Bernard; Herrera, G.; Pasqual, C.; Grimalt, J. O.; Galavazi, M.; Schneider, R.. |
| Borehole PRGL1-4 drilled in the upper slope of the Gulf of Lion provides an exceptional record to investigate the impact of late Pleistocene orbitally-driven glacio-eustatic sea-level oscillations on the sedimentary outbuilding of a river fed continental margin. High-resolution grain-size and geochemical records supported by oxygen isotope chronostratigraphy allow reinterpreting the last 500 ka upper slope seismostratigraphy of the Gulf of Lion. Five main sequences, stacked during the sea-level lowering phases of the last five glacial-interglacial 100-kyr cycles, form the upper stratigraphic outbuilding of the continental margin. The high sensitivity of the grain-size record down the borehole to sea-level oscillations can be explained by the great width of... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00088/19944/17599.pdf |
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| Stuut, Jan‐berend W.; De Deckker, Patrick; Saavedra‐pellitero, Mariem; Bassinot, Franck; Drury, Anna‐joy; Walczak, Maureen H.; Nagashima, Kana; Murayama, Masafumi. |
| New proxy records from deep‐sea sediment cores from the northwestern continental margin of Western Australian reveal a 5.3 million‐year (Ma) history of aridity and tropical‐monsoon activity in northwestern Australia. Following the warm and dry early Pliocene (~5.3 Ma), the northwestern Australian continent experienced a gradual increase in humidity peaking at about 3.8 Ma with higher than present‐day rainfall. Between 3.8 and about 2.8 Ma, climate became progressively more arid with more rainfall variability. Coinciding with the onset of the northern hemisphere glaciations and the intensification of the northern hemisphere monsoon, aridity continued to increase overall from 2.8 Ma until today, with greater variance in precipitation and an increased... |
| Tipo: Text |
Palavras-chave: Paleoclimate; Monsoon; Australia; Runoff; Pliocene; Quaternary. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00502/61384/65035.pdf |
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| Rintoul, Sr; Sokolov, S; Church, J. |
| Repeat hydrographic sections across the Antarctic Circumpolar Current are used to derive an empirical relationship between upper ocean temperature and the baroclinic transport stream function. Cross validation shows this relationship can be used to infer baroclinic transport (above and relative to 2500 dbar) from temperature measurements with an error of a few per cent. The mean transport distribution derived from 31 austral summer expendable bathythermograph (XBT) sections over a 6 year period consists of westward flow immediately south of Tasmania, a broad band of strong eastward flow between 50degrees and 55degreesS, and three cores of eastward flow south of 55degreesS. By defining a second empirical relationship between surface dynamic height and... |
| Tipo: Text |
Palavras-chave: Baroclinic transport; Antarctic Circumpolar Current; Interannual variability; Satellite altimeter; XBT. |
| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33444/31832.pdf |
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| Svensson, A.; Andersen, K. K.; Bigler, M.; Clausen, H. B.; Dahl-jensen, D.; Davies, S. M.; Johnsen, S. J.; Muscheler, R.; Parrenin, F.; Rasmussen, S. O.; Roethlisberger, R.; Seierstad, I.; Steffensen, J. P.; Vinther, B. M.. |
| The Greenland Ice Core Chronology 2005 (GICC05) is a time scale based on annual layer counting of high-resolution records from Greenland ice cores. Whereas the Holocene part of the time scale is based on various records from the DYE-3, the GRIP, and the NorthGRIP ice cores, the glacial part is solely based on NorthGRIP records. Here we present an 18 ka extension of the time scale such that GICC05 continuously covers the past 60 ka. The new section of the time scale places the onset of Greenland Interstadial 12 (GI-12) at 46.9 +/- 1.0 ka b2k (before year AD 2000), the North Atlantic Ash Zone II layer in GI-15 at 55.4 +/- 1.2 ka b2k, and the onset of GI-17 at 59.4 +/- 1.3 ka b2k. The error estimates are derived from the accumulated number of uncertain annual... |
| Tipo: Text |
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| Ano: 2008 |
URL: https://archimer.ifremer.fr/doc/00238/34893/33135.pdf |
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| Patton, Jason R.; Goldfinger, Chris; Morey, Ann E.; Ikehara, Ken; Romsos, Chris; Stoner, Joseph; Djadjadihardja, Yusuf; Udrekh,; Sri Ardhyastuti,; Gaffar, Eddy Zulkarnaen; Vizcaino, Alexis. |
| In order to investigate the possibility of a long-term paleoseismic history from offshore sedimentary records in Sumatra, we collected 144 deep-sea sedi-ment cores in the trench and in lower slope piggyback basins of the Sumatra accretionary prism. We used multibeam bathymetry and seismic reflection data to develop an understanding of catchment basins, turbidity current pathways, and depositional styles, as well as to precisely locate our gravity cores, piston cores, Kasten cores, and multicores. We use detailed physical property data, including computed tomographic X-ray, gamma density, magnetic susceptibility, grain-size analysis, faunal analysis, and smear slides, to evaluate the turbidite stratigraphy and sedimentology at each site. We use radiocarbon... |
| Tipo: Text |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00351/46229/46162.pdf |
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| Drouineau, Hilaire; Lobry, Jeremy; Delpech, C.; Bouchoucha, Marc; Mahevas, Stephanie; Courrat, A.; Pasquaud, S.; Lepage, M.. |
| In the context of the European Water Framework Directive (WFD), monitoring programs and related indicators have been developed to assess anthropogenic impacts on various components of aquatic ecosystems. While great precautions are usually taken when selecting and calculating relevant core metrics, little attention is generally paid to the generation of the multimetric indicator, i.e. the combination of the different core metrics. Indeed, most multimetric indicators are generated by simply averaging or summing metrics, without taking into account their sensitivity and their variability. Moreover, few indicators provide a rigorous estimate of the uncertainty of the assessments, while this estimation is essential for managers. In this context, we developed a... |
| Tipo: Text |
Palavras-chave: Multimetric fish-based indicator; Bayesian method; Pressure-impact models; Water Framework Directive; Anthropogenic pressure; Monitoring program; Transitional waters. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00049/16037/13572.pdf |
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| Marandel, Florianne; Lorance, Pascal; Trenkel, Verena M.. |
| The thornback ray (Raja clavata) in the Bay of Biscay is presumed to have declined during the 20th Century. To evaluate this decline and estimate biomass trajectories, a hypothetical catch time series was created for the period 1903-2013. A Bayesian state-space biomass production model with a Schaefer production function was fitted to the hypothetical catch time series and to a shorter research vessel Catch Per Unit Eeffort (CPUE) time series (1973-2013, with missing years). A censored likelihood made it possible to obtain biomass estimates without a CPUE time series or only with an estimate of biomass depletion. A simulation-estimation approach showed a high sensitivity of results to the prior for the intrinsic growth rate. The model provided biomass... |
| Tipo: Text |
Palavras-chave: Population dynamics; Stock assessment; Data poor; Censored data; Bayes; Thornback ray; State-space model. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00359/47032/46947.pdf |
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| Alemany, Juliette; Rivot, Etienne; Foucher, Eric; Vigneau, Joel; Robin, Jean-paul. |
| Among the English Channel fishery, the importance of cuttlefish stock has increased, following the cephalopods global landings and market trend. An adapted stock assessment model is needed in order to give good management advice with accurate uncertainties. Age based methods in this species are hampered by time consuming age determination with statoliths. A model requiring few data and adapted to the species life-history is therefore proposed. An assessment of this stock was conducted in June 2015 by fitting a two-stage biomass model on a 22 years’ time-series (1992-2014). The use of a Bayesian framework is particularly adapted for decision making, allowing the propagation of uncertainty in the model. It also permits the use of different sources of... |
| Tipo: Text |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00379/49066/49514.pdf |
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| Politikos, Dimitrios; Huret, Martin; Petitgas, Pierre. |
| Modelling of fish movement behaviour within a heterogeneous marine environment is a challenging but also key issue for understanding the effect of environmental factors and climatic change on fish processes (growth, distribution, mortality, reproduction). Fish movement models have the capability to encompass the combined effect of environment and empirical knowledge of fish individuals as energy requirements, known preys and predators, swimming capacities into a unified framework. Following an Individual Based Model (IBM) approach, a fish movement model has been developed to simulate the active movement of adult anchovy in the Bay of Biscay (BoB) in response to the spatio-temporal variations of both biotic and abiotic factors, as well as its internal... |
| Tipo: Text |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00176/28709/27161.pdf |
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| Ragueneau, O.; Regaudie-de-gioux, A.; Moriceau, B.; Gallinari, M.; Vangriesheim, Annick; Baurand, F.; Khripounoff, Alexis. |
| To elucidate the origin of the silicic acid (DSi) anomaly observed along the 4000 isobath on the Congo margin, we have established a benthic Si mass balance and performed direct measurements of biogenic silica (bSiO(2)) dissolution in the deep waters and in the sediments. Results strongly suggest that the anomaly originates from the sediments; the intensity of DSi recycling is consistent with the degradation of organic matter, as observed from Si:O-2 ratios in the benthic fluxes compared to that ratio observed in the anomalies. Strong imbalances, observed in both the Si and C mass balances, suggest that the biogenic matter that degrades and dissolves in these sediments near 4000 m does not come from pelagic sedimentation. It is probably not coming also... |
| Tipo: Text |
Palavras-chave: Congo; Continental margin; Preservation; Dissolution; Biogenic silica. |
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/2009/publication-7410.pdf |
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| Registros recuperados: 45.096 | |
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