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| Registros recuperados: 20 | |
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| Le Gland, Guillaume; Aumont, Olivier; Memery, Laurent. |
| Thorium-234 (Th-234), an insoluble radioisotope scavenged by marine particles, can be used as a proxy of the biological carbon pump. Thorium-234 observations can constrain biogeochemical models, but a necessary first step is to estimate the poorly known partition coefficients between particulate and dissolved phases. In this study, the Th-234 partition coefficients for five particle types, differing in size and chemical composition, are estimated by fitting a global 3-D Th-234 model based on the coupled ocean general circulation-biogeochemistry model NEMO-PISCES (at a resolution of 2 degrees) to a global Th-234 data set (including GEOTRACES data). Surface partition coefficients are estimated between 0.79 and 16.7x10(6). Biogenic silica has the smallest... |
| Tipo: Text |
Palavras-chave: Thorium 234; Inverse modeling; Partition coefficient; Biological carbon pump. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00605/71666/70108.pdf |
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| Cadier, Mathilde; Gorgues, Thomas; Sourisseau, Marc; Edwards, Christopher A.; Aumont, Olivier; Marie, Louis; Memery, Laurent. |
| Understanding the dynamic interplay between physical, biogeochemical and biological processes represents a key challenge in oceanography, particularly in shelf seas where complex hydrodynamics are likely to drive nutrient distribution and niche partitioning of phytoplankton communities. The Iroise Sea includes a tidal front called the ‘Ushant Front’ that undergoes a pronounced seasonal cycle, with a marked signal during the summer. These characteristics as well as relatively good observational sampling make it a region of choice to study processes impacting phytoplankton dynamics. This innovative modeling study employs a phytoplankton-diversity model, coupled to a regional circulation model to explore mechanisms that alter biogeography of phytoplankton in... |
| Tipo: Text |
Palavras-chave: Iroise Sea; Tidal mixing front; Biogeochemical modeling; Phytoplankton; Functional groups; Seasonal cycle. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00352/46367/45986.pdf |
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| Cadier, Mathilde; Sourisseau, Marc; Gorgues, Thomas; Edwards, Christopher A.; Memery, Laurent. |
| Tidal front ecosystems are especially dynamic environments usually characterized by high phytoplankton biomass and high primary production. However, the description of functional microbial diversity occurring in these regions remains only partially documented. In this article, we use a numerical model, simulating a large number of phytoplankton phenotypes to explore the three-dimensional spatial patterns of phytoplankton abundance and diversity in the Iroise Sea (western Brittany). Our results suggest that, in boreal summer, a seasonally marked tidal front shapes the phytoplankton species richness. A diversity maximum is found in the surface mixed layer located slightly west of the tidal front (i.e., not strictly co-localized with high biomass... |
| Tipo: Text |
Palavras-chave: Plankton functional traits; Biodiversity; Biogeography; Local adaptation; Dynamical transport; Tidal front. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00367/47861/48101.pdf |
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| Memery, Laurent; Arhan, Michel; Daniault, Nathalie; Hemon, Catherine; Mercier, Herle; Chipman, David W.; Groupe CITHER 2. |
| De janvier à Mars 1994 s'est déroulée la campagne CITHER 2 du programme WOCE-France, dans le but d'étudier les écoulements le long du bord Ouest de l'Océan Atlantique Sud. Les paramètres hydrologiques et géochimiques requis par le Programme Hydrologique de WOCE (WHP) ont été mesurés de la surface au fond, à 235 stations situées le long d'une radiale quasi-méridienne allant de 52° S à 10° N à environ 600 km du talus continental et, transversalement à cette radiale, le long de trois segments allant jusqu'au talus continental à environ 35° S, 13° S, et 10° N. Ce rapport, qui est le premier des trois recueils de données CITHER 2, contient une brève description générale du programme CITHER et de la campagne CITHER 2, suivie d'une présentation des paramètres "en... |
| Tipo: Text |
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| Ano: 1996 |
URL: http://archimer.ifremer.fr/doc/00238/34905/33175.pdf |
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| Memery, Laurent; Arhan, Michel; Billant, Andre; Branellec, Pierre; Mercier, Herle; Groupe CITHER 2. |
| De janvier à Mars 1994 s'est déroulée la campagne CITHER 2 du programme WOCE-France, dans le but d'étudier les écoulements le long du bord Ouest de l'Océan Atlantique Sud. Les paramètres hydrologiques et géochimiques requis par le Programme Hydrologique de WOCE (WHP) ont été mesurés de la surface au fond, à 235 stations situées le long d'une radiale quasi-méridienne allant de 52° S à 10° N à environ 600 km du talus continental et, transversalement à cette radiale, le long de trois segments allant jusqu'au talus continental à environ 35° S, 13° S, et 10° N. Ce rapport, qui est le deuxième volume de la série des recueils de données CITHER 2, présente les mesures des paramètres de la bathysonde (pression, température, salinité, et oxygène dissous). Les... |
| Tipo: Text |
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| Ano: 1995 |
URL: http://archimer.ifremer.fr/doc/00238/34906/33180.pdf |
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| Memery, Laurent; Messias, Marie-josé; Arhan, Michel; Billant, Andre; Branellec, Pierre; Mercier, Herle; Alvarez Salgado, Xosé; Gonzales Castro, Carmen; Rios, Aida F.; Roson, Gabriel; Arlen, Linda; Bingler, Linda; Groupe CITHER 2. |
| De janvier à Mars 1994 s'est déroulée la campagne CITHER 2 du programme WOCE-France, dans le but d'étudier les écoulements le long du bord Ouest de l'Océan Atlantique Sud. Les paramètres hydrologiques et géochimiques requis par le Programme Hydrologique de WOCE (WHP) ont été mesurés de la surface au fond, à 235 stations situées le long d'une radiale quasi-méridienne allant de 52° S à 10° N à environ 600 km du talus continental et, transversalement à cette radiale, le long de trois segments allant jusqu'au talus continental à environ 35° S, 13° S, et 10° N. Ce rapport, qui est le troisième volume de la série des recueils de données CITHER 2, présente les mesures des paramètres géochimiques mesurés sur prélèvements d'eau (salinité, oxygène dissous, sels... |
| Tipo: Text |
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| Ano: 1996 |
URL: http://archimer.ifremer.fr/doc/00238/34907/33185.pdf |
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| Arhan, Michel; Billant, Andre; Branellec, Pierre; Mercier, Herle; Memery, Laurent; Messias, Marie-josé; Morin, Pascal; Wafar, Mohideen; Alvarez Salgado, Xosé; Aristegui, Javier; Gonzalez-davila, Melchor; Pazo Fernandez, Maria José; Rellan, Trinidad; Rios, Aida; Bingler, Linda; Groupe CITHER 3. |
| De mi-janvier à début avril 1995 s'est déroulée la campagne CITHER 3 du programme WOCE-France, dans le but d'étudier les écoulements aux frontières méridiennes du bassin Atlantique Sud-Est: à l'ouest, les échanges avec les Bassins d'Argentine et du Brésil, et à l'est, les écoulements le long du talus continental Africain. Les paramètres hydrologiques et géochimiques requis par le Programme Hydrologique de WOCE (WHP) ont été mesurés de la surface au fond à 242 stations situées le long de deux radiales, l'une à 9° W entre le talus continental Ivoirien et la latitude 45° S, l'autre de Cape Town à la position 40° S - 10° E, puis au talus continental Ghanéen. Ce rapport, qui est le troisième volume de la série des recueils de données CITHER 3, présente les... |
| Tipo: Text |
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| Ano: 1998 |
URL: http://archimer.ifremer.fr/doc/00238/34920/33291.pdf |
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| Mercier, Herle; Billant, Andre; Branellec, Pierre; Morin, Pascal; Messias, Marie-josé; Memery, Laurent; Thomas, Catherine; Honnorez, Jose. |
| La campagne Romanche 1 s'est déroulée du 10 août au 7 septembre 1991, en un leg Dakar-Dakar, à bord du navire de recherche océanographique de l'Ifremer L'Atalante. Romanche 1, première campagne dans le cadre du projet Romanche, avait pour but d'explorer l'hydrologie et la bathymétrie des zones de fracture Romanche et Chain centrées respectivement à l'équateur et vers 1°S dans l'Atlantique. L'analyse des données recueillies fournira l'information nécessaire à la définition et au positionnement de mouillages courantométriques qui permettront de mesurer le flux d'Eau Antarctique de Fond (EAF) passant du bassin Ouest au bassin Est de l'Atlantique par ces 2 zones de fracture. Quatre mouillages seront déployés dans la zone de fracture Romanche, 4 dans la zone de... |
| Tipo: Text |
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| Ano: 1992 |
URL: http://archimer.ifremer.fr/doc/00233/34414/32811.pdf |
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| Holt, Jason; Allen, J. Icarus; Anderson, Thomas R.; Brewin, Robert; Butenschoen, Momme; Harle, James; Huse, Geir; Lehodey, Patrick; Lindemann, Christian; Memery, Laurent; Salihoglu, Buis; Senina, Inna; Yool, Andrew. |
| It has long been recognised that there are strong interactions and feedbacks between climate, upper ocean biogeochemistry and marine food webs, and also that food web structure and phytoplankton community distribution are important determinants of variability in carbon production and export from the euphotic zone. Numerical models provide a vital tool to explore these interactions, given their capability to investigate multiple connected components of the system and the sensitivity to multiple drivers, including potential future conditions. A major driver for ecosystem model development is the demand for quantitative tools to support ecosystem-based management initiatives. The purpose of this paper is to review approaches to the modelling of marine... |
| Tipo: Text |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00213/32434/30901.pdf |
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| Raimonet, Melanie; Ragueneau, Olivier; Andrieux-loyer, Francoise; Khalil, Karima; Kerouel, Roger; Philippon, Xavier; Soetaert,, Karline; Rabouille, Christophe; Memery, Laurent. |
| Tipo: Text |
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| Ano: 2011 |
URL: http://archimer.ifremer.fr/doc/00058/16909/14382.pdf |
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| Omar, Youssouf Moussa; Memery, Laurent; Carton, Xavier; Daher, Abdourahman; Duvielbourg, Eric. |
| The vertical thermohaline and biogeochemical structures of the upper layer (0 - 200 m) were studied in the Gulf of Tadjourah using high-resolution hydrographic data collected in July-August 2013, September 2013 and February 2014. During summer, the superficial layer consisted of the mixed layer (ML) extending to a depth of about 20 - 30 m followed by the thermocline located between 30 and 50 m depth. The ML was thicker in the west and the southeast where the thermal gradient and chlorophyll a concentrations were particularly high. During September, this stratification persisted but the ML became warmer and saltier and the thermocline moved slightly deeper. In February, the ML extended to about 120 m, and the thermocline was less pronounced. A comparison of... |
| Tipo: Text |
Palavras-chave: Thermohaline; Biogeochemical Structures; Mixed Layer Depth; Thermocline; Monsoon Wind; Topography. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00601/71286/69693.pdf |
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| Le Gland, Guillaume; Memery, Laurent; Aumont, Olivier; Resplandy, Laure. |
| Radium-228 (Ra-228), an almost conservative trace isotope in the ocean, supplied from the continental shelves and removed by a known radioactive decay (T-1/2 - 5.75 years), can be used as a proxy to constrain shelf fluxes of other trace elements, such as nutrients, iron, or rare earth elements. In this study, we perform inverse modeling of a global Ra-228 dataset (including GEOSECS, TTO and GEOTRACES programs, and, for the first time, data from the Arctic and around the Kerguelen Islands) to compute the total Ra-228 fluxes toward the ocean, using the ocean circulation obtained from the NEMO 3.6 model with a 2 degrees resolution. We optimized the inverse calculation (source regions, cost function) and find a global estimate of the Ra-228 fluxes of 8.01-8.49... |
| Tipo: Text |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00616/72811/72571.pdf |
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| Lemonnier, Clarisse; Perennou, Morgan; Eveillard, Damien; Fernandez-guerra, Antonio; Leynaert, Aude; Marié, Louis; Morrison, Hilary G.; Memery, Laurent; Paillard, Christine; Maignien, Lois. |
| Ocean frontal systems are widespread hydrological features defining the transition zone between distinct water masses. They are generally of high biological importance as they are often associated with locally enhanced primary production by phytoplankton. However, the composition of bacterial communities in the frontal zone remains poorly understood. In this study, we investigate how a coastal tidal front in Brittany (France) structures the free-living bacterioplankton communities in a spatio-temporal survey across four cruises, five stations and three depths. We used 16S rRNA gene surveys to compare bacterial community structures across 134 seawater samples and defined groups of co-varying taxa (modules) exhibiting coherent ecological patterns across... |
| Tipo: Text |
Palavras-chave: Marine front; Bacterial communities; Dynamic; Network; Ecological strategies. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00634/74657/74557.pdf |
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| Maze, Guillaume; Mercier, Herle; Thierry-theetten, Virginie; Memery, Laurent; Morin, P.; Perez, F.f.. |
| The northeast Atlantic is a key horizontal and vertical crossroads region for the meridional overturning circulation, but basic nutrient and oxygen fluxes are still poorly constrained by observations in the region. A surface to bottom northeast Atlantic Ocean budget for mass, nutrients (nitrate and phosphate) and oxygen is determined using an optimization method based on three surveys of the OVIDE transect (from Greenland to Portugal) completed with the World Ocean Atlas 2009. Budgets are derived for two communicating boxes representing the northeastern European basin (NEEB) and the Irminger Sea. For the NEEB (Irminger) box, it is found that 30% of the mass import (export) across the OVIDE section reach (originate from) the Nordic Seas, while 70% are... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00100/21101/18724.pdf |
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| Ramond, Pierre; Siano, Raffaele; Schmitt, Sophie; De Vargas, Colomban; Marié, Louis; Memery, Laurent; Sourisseau, Marc. |
| Oceanic physics at fine scale; e.g. eddies, fronts, filaments; are notoriously difficult to sample. However, an increasing number of theoretical approaches hypothesize that these processes affect phytoplankton diversity which have cascading effects on regional ecosystems. In 2015, we targeted the Iroise Sea (France) and evidenced the setting up of the Ushant tidal front from the beginning of spring to late summer. Seawater samples were taken during three sampling cruises and DNA-barcoding allowed us to investigate patterns of eukaryotic phytoplankton diversity across this front. First focusing on patterns of taxonomic richness, we evidenced that the front harbored a hotspot of eukaryotic phytoplankton diversity sustained throughout summer. We then detail... |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00677/78933/81307.pdf |
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| Gorgues, Thomas; Aumont, Olivier; Memery, Laurent. |
| Diel vertical migration (DVM) of zooplankton has been recognized to influence the biological pump by releasing carbon and nutrients at depth. However, uncertainties regarding the magnitude, spatial occurrence and variability of this “active transport”, as well as its impact on the carbon export, remain. To tackle these questions, a cost‐effective parameterization of the DVM is included into a regional biogeochemical model simulating the North Atlantic. In addition to a reference simulation in which no DVM is simulated, two relative biomasses of migrating zooplankton (30% and 60%) have been tested. It leads to an active to passive export ratio in agreement with published estimations and to an increase in the carbon export efficiency at 1000m between 20 and... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00493/60428/63868.pdf |
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| Raimonet, Melanie; Ragueneau, Olivier; Andrieux Loyer, Francoise; Philippon, Xavier; Kerouel, Roger; Le Goff, Manon; Memery, Laurent. |
| The high heterogeneity of silica cycling in coastal margins and the lack of silica data (compared to nitrogen and phosphorus) prevent the estimation of global silica retention in estuaries. In this study, the spatial and temporal variability of porewater silicic acid (Si(OH)4) profiles e that integrate benthic transport and reaction processes e was investigated at different spatial (metre, longitudinal and crosssection, intra-estuary) and temporal (tidal, seasonal) scales in two macrotidal estuaries, very close geographically but essentially differing in their shape. Studying the spatial and temporal variability of Si(OH)4 concentrations in porewaters provided evidence for the importance of transport processes, e.g. bio-irrigation, tidal pumping,... |
| Tipo: Text |
Palavras-chave: Heterogeneity; Season; Silicate; Sediment; Land-sea interface; Upscaling. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00124/23529/22370.pdf |
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| Registros recuperados: 20 | |
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