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| Registros recuperados: 33 | |
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| Ishii, M.; Feely, R. A.; Rodgers, K. B.; Park, G. -h.; Wanninkhof, R.; Sasano, D.; Sugimoto, H.; Cosca, C. E.; Nakaoka, S.; Telszewski, M.; Nojiri, Y.; Fletcher, S. E. Mikaloff; Niwa, Y.; Patra, P. K.; Valsala, V.; Nakano, H.; Lima, I.; Doney, S. C.; Buitenhuis, E. T.; Aumont, Olivier; Dunne, J. P.; Lenton, A.; Takahashi, T.. |
| Air-sea CO2 fluxes over the Pacific Ocean are known to be characterized by coherent large-scale structures that reflect not only ocean subduction and upwelling patterns, but also the combined effects of wind-driven gas exchange and biology. On the largest scales, a large net CO2 influx into the extratropics is associated with a robust seasonal cycle, and a large net CO2 efflux from the tropics is associated with substantial interannual variability. In this work, we have synthesized estimates of the net air-sea CO2 flux from a variety of products, drawing upon a variety of approaches in three sub-basins of the Pacific Ocean, i. e., the North Pacific extratropics (18-66 degrees N), the tropical Pacific (18 degrees S-18 degrees N), and the South Pacific... |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00192/30320/28789.pdf |
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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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| Tagliabue, Alessandro; Barrier, Nicolas; Du Pontavice, Hubert; Kwiatkowski, Lester; Aumont, Olivier; Bopp, Laurent; Cheung, William W. L.; Gascuel, Didier; Maury, Olivier. |
| Earth System Models project that global climate change will reduce ocean net primary production (NPP), upper trophic level biota biomass and potential fisheries catches in the future, especially in the eastern equatorial Pacific. However, projections from Earth System Models are undermined by poorly constrained assumptions regarding the biological cycling of iron, which is the main limiting resource for NPP over large parts of the ocean. In this study, we show that the climate change trends in NPP and the biomass of upper trophic levels are strongly affected by modifying assumptions associated with phytoplankton iron uptake. Using a suite of model experiments, we find 21st century climate change impacts on regional NPP range from −12.3% to +2.4% under a... |
| Tipo: Text |
Palavras-chave: Climate change; Iron; Marine ecosystems; Net primary production; Ocean. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00652/76417/77470.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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| Moreau, Sebastien; Vancoppenolle, Martin; Bopp, Laurent; Aumont, Olivier; Madec, Gurvan; Delille, Bruno; Tison, Jean-louis; Barriat, Pierre-yves; Goosse, Hugues. |
| The role of sea ice in the carbon cycle is minimally represented in current Earth System Models (ESMs). Among potentially important flaws, mentioned by several authors and generally overlooked during ESM design, is the link between sea-ice growth and melt and oceanic dissolved inorganic carbon (DIC) and total alkalinity (TA). Here we investigate whether this link is indeed an important feature of the marine carbon cycle misrepresented in ESMs. We use an ocean general circulation model (NEMO-LIM-PISCES) with sea-ice and marine carbon cycle components, forced by atmospheric reanalyses, adding a first-order representation of DIC and TA storage and release in/from sea ice. Our results suggest that DIC rejection during sea-ice growth releases several hundred Tg... |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00664/77572/79539.pdf |
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| Dufresne, J-l.; Foujols, M-a.; Denvil, S.; Caubel, A.; Marti, O.; Aumont, Olivier; Balkanski, Y.; Bekki, S.; Bellenger, H.; Benshila, R.; Bony, S.; Bopp, L.; Braconnot, P.; Brockmann, P.; Cadule, P.; Cheruy, F.; Codron, F.; Cozic, A; Cugnet, D.; De Noblet, N.; Duvel, J-p.; Ethe,; Fairhead, L.; Fichefet, T.; Flavoni, S.; Friedlingstein, P.; Grandpeix, J-y.; Guez, L.; Guilyardi, E.; Hauglustaine, D.; Hourdin, F.; Idelkadi, A.; Ghattas, J.; Joussaume, S.; Kageyama, M.; Krinner, G.; Labetoulle, S.; Lahellec, A.; Lefebvre, M; Lefevre, F.; Levy, C.; Li, Zhanbin; Lloyd, J.; Lott, F.; Madec, G.; Mancip, M.; Marchand, M; Masson, S.; Meurdesoif, Y.; Mignot, J.; Musat, I.; Parouty, S.; Polcher, J.; Rio, C; Schulz, M.; Swingedouw, D.; Szopa, S.; Talandier, Claude; Terray, P.; Viovy, N.; Vuichard, N.. |
| We present the global general circulation model IPSL-CM5 developed to study the long-term response of the climate system to natural and anthropogenic forcings as part of the 5th Phase of the Coupled Model Intercomparison Project (CMIP5). This model includes an interactive carbon cycle, a representation of tropospheric and stratospheric chemistry, and a comprehensive representation of aerosols. As it represents the principal dynamical, physical, and bio-geochemical processes relevant to the climate system, it may be referred to as an Earth System Model. However, the IPSL-CM5 model may be used in a multitude of configurations associated with different boundary conditions and with a range of complexities in terms of processes and interactions. This paper... |
| Tipo: Text |
Palavras-chave: Climate; Climate change; Climate projections; Earth System Model; CMIP5; CMIP3; Greenhouse gases; Aerosols; Carbon cycle; Allowable emissions; RCP scenarios; Land use changes. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00138/24966/23079.pdf |
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| Keerthi, M. G.; Levy, M.; Aumont, Olivier; Lengaigne, Matthieu; Antoine, D.. |
| Understanding long‐term variations of ocean ecosystems requires untangling the time scales involved in their natural fluctuations. We applied a temporal decomposition procedure to two decades of satellite ocean color observations to characterize the time variability of surface Chlorophyll‐a (SChl) in the Mediterranean Sea. In order to assess the reliability of the satellite data at capturing intraseasonal, seasonal and interannual variability, we first show that satellite SChl data compare well with field data of phytoplankton fluorescence from the long‐term BOUSSOLE time series, at all three timescales. The decomposition procedure is then applied to satellite SChl and to mixing‐layer depth (MxLD) data from an ocean reanalysis, both at the scale of the... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00624/73654/73098.pdf |
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| Aumont, Olivier; Belviso, Sauveur; Monfray, Patrick. |
| [1] A global model for surface dimethylsulfide (DMS) and particulate dimethylsulfoniopropionate (DMSP) (pDMS) distributions is presented. The main goals of this work were to be able to predict the regional distribution of the air-sea fluxes of DMS and to predict eventually their future evolution with climate change. Diagnostic relationships have been established from data sets obtained during the ALBATROSS and EUMELI cruises carried out in the Atlantic Ocean. These equations nonlinearly relate DMS and pDMSP concentrations to chlorophyll concentrations and to the trophic status of surface waters. This model has been embedded in the global ocean carbon cycle model Institut Pierre et Simon Laplace-Ocean Carbon Cycle Model version 2 (ISPL-OCCM2), a simple... |
| Tipo: Text |
Palavras-chave: Ocean; Biogeochemistry; Ecosystem modeling; DMS; Global. |
| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33448/31824.pdf |
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| Laufkoetter, C.; Vogt, M.; Gruber, N.; Aita-noguchi, M.; Aumont, Olivier; Bopp, L.; Buitenhuis, E.; Doney, S. C.; Dunne, J.; Hashioka, T.; Hauck, J.; Hirata, T.; John, J.; Le Quere, C.; Lima, I. D.; Nakano, H.; Seferian, R.; Totterdell, I.; Vichi, M.; Voelker, C.. |
| Past model studies have projected a global decrease in marine net primary production (NPP) over the 21st century, but these studies focused on the multi-model mean rather than on the large inter-model differences. Here, we analyze model-simulated changes in NPP for the 21st century under IPCC's high-emission scenario RCP8.5. We use a suite of nine coupled carbon-climate Earth system models with embedded marine ecosystem models and focus on the spread between the different models and the underlying reasons. Globally, NPP decreases in five out of the nine models over the course of the 21st century, while three show no significant trend and one even simulates an increase. The largest model spread occurs in the low latitudes (between 30 degrees S and 30... |
| Tipo: Text |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00302/41333/40511.pdf |
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| Seferian, Roland; Nabat, Pierre; Michou, Martine; Saint-martin, David; Voldoire, Aurore; Colin, Jeanne; Decharme, Bertrand; Delire, Christine; Berthet, Sarah; Chevallier, Matthieu; Senesi, Stephane; Franchisteguy, Laurent; Vial, Jessica; Mallet, Marc; Joetzjer, Emilie; Geoffroy, Olivier; Gueremy, Jean-francois; Moine, Marie-pierre; Msadek, Rym; Ribes, Aurelien; Rocher, Matthias; Roehrig, Romain; Salas-y-melia, David; Sanchez, Emilia; Terray, Laurent; Valcke, Sophie; Waldman, Robin; Aumont, Olivier; Bopp, Laurent; Deshayes, Julie; Ethe, Christian; Madec, Gurvan. |
| This study introduces CNRM-ESM2-1, the Earth system (ES) model of second generation developed by CNRM-CERFACS for the sixth phase of the Coupled Model Intercomparison Project (CMIP6). CNRM-ESM2-1 offers a higher model complexity than the Atmosphere-Ocean General Circulation Model CNRM-CM6-1 by adding interactive ES components such as carbon cycle, aerosols, and atmospheric chemistry. As both models share the same code, physical parameterizations, and grid resolution, they offer a fully traceable framework to investigate how far the represented ES processes impact the model performance over present-day, response to external forcing and future climate projections. Using a large variety of CMIP6 experiments, we show that represented ES processes impact more... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00676/78800/81052.pdf |
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| Arrizabalaga, Haritz; Dufour, Florence; Kell, Laurence; Merino, Gorka; Ibaibarriaga, Leire; Chust, Guillem; Irigoien, Xabier; Santiago, Jose Luis; Murua, Hilario; Fraile, Igaratza; Chifflet, Marina; Goikoetxea, Nerea; Sagarminaga, Yolanda; Aumont, Olivier; Bopp, Laurent; Herrera, Miguel; Fromentin, Jean-marc; Bonhomeau, Sylvain. |
| In spite of its pivotal role in future implementations of the Ecosystem Approach to Fisheries Management, current knowledge about tuna habitat preferences remains fragmented and heterogeneous, because it relies mainly on regional or local studies that have used a variety of approaches making them difficult to combine. Therefore in this study we analyse data from six tuna species in the Pacific, Atlantic and Indian Oceans in order to provide a global, comparative perspective of habitat preferences. These data are longline catch per unit effort from 1958 to2007 for albacore, Atlantic bluefin, southern bluefin, bigeye, yellowfin and skipjack tunas. Both quotient analysis and Generalized Additive Models were used to determine habitat preference with respect to... |
| Tipo: Text |
Palavras-chave: Habitat; Tuna fisheries; Catch/effort; Environmental conditions; Quotient analysis; Generalised Additive Models; Ecosystem Approach to Fisheries Management. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00201/31190/29589.pdf |
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| Menkes, Christophe E.; Lengaigne, Matthieu; Levy, Marina; Ethe, Christian; Bopp, Laurent; Aumont, Olivier; Vincent, Emmanuel; Vialard, Jerome; Jullien, Swen. |
| In this paper, we explore the global responses of surface temperature, chlorophyll and primary production to tropical cyclones (TCs). Those ocean responses are first characterized from the statistical analysis of satellite data under ~1000 TCs over the 1998-2007 period. Besides the cold wake, the vast majority of TCs induce a weak chlorophyll response, with only ~10% of induced blooms exceeding 0.1 mg.m-3. The largest chlorophyll responses mostly occur within coastal regions, in contrast to the strongest cold wakes that generally occur farther offshore. To understand this decoupling, we analyze a coupled dynamical-biogeochemical oceanic simulation forced by realistic wind vortices applied along observed TC tracks. The simulation displays a realistic... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00333/44449/44121.pdf |
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| Beghoura, H.; Gorgues, Thomas; Aumont, Olivier; Planquette, Helene; Tagliabue, A.; Auger, P.‐a.. |
| Iron is known to be the limiting nutrient for the phytoplankton growth over ~40% of the global ocean and to impact the structure of marine ecosystems. Dissolved iron (DFe) is assumed to be the only form available to phytoplankton while particulate iron (PFe) has mostly been considered for its role in the biogenic iron remineralization and induced scavenging. Therefore, most studies focused on the nature of DFe external sources to the ocean (i.e. aeolian dust, riverine fluxes, hydrothermal sources and sediment) and their quantification, which still remain uncertain. Among these external sources, the sedimentary sources have been shown to be underestimated. Moreover, the iron supply from sediments has been documented to be often larger in the particle... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00591/70270/68330.pdf |
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| Albert, A.; Echevin, V.; Levy, M; Aumont, Olivier. |
| Coastal upwelling dynamics are strongly affected by alongshore wind stress and nearshore wind stress curl. A coupled physical-biogeochemical regional model and lagrangian diagnostics are used in the Peru current system to determine how the upwelling of nutrients and the primary productivity are impacted by the spatial structure of the nearshore wind stress. Three wind stress products derived from the ERS and QuikSCAT scatterometers and a smoothed QuikSCAT field, mainly differing in nearshore wind stress curl patterns, were used. Simulations are found to produce significantly different mean surface chlorophyll distributions and show that strong upwelling-favorable nearshore wind stress curl may locally induce a wide coastal productive zone through upwelling... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00025/13648/10882.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... |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00616/72811/72571.pdf |
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| Currie, J. C.; Lengaigne, M.; Vialard, Jerome; Kaplan, David; Aumont, Olivier; Naqvi, S. W. A.; Maury, Olivier. |
| The Indian Ocean Dipole (IOD) and the El Nino/Southern Oscillation (ENSO) are independent climate modes, which frequently co-occur, driving significant interannual changes within the Indian Ocean. We use a four-decade hindcast from a coupled biophysical ocean general circulation model, to disentangle patterns of chlorophyll anomalies driven by these two climate modes. Comparisons with remotely sensed records show that the simulation competently reproduces the chlorophyll seasonal cycle, as well as open-ocean anomalies during the 1997/1998 ENSO and IOD event. Results suggest that anomalous surface and euphotic-layer chlorophyll blooms in the eastern equatorial Indian Ocean in fall, and southern Bay of Bengal in winter, are primarily related to IOD forcing.... |
| Tipo: Text |
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| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00166/27749/25945.pdf |
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| Toyama, Katsuya; Rodgers, Keith B.; Blanke, Bruno; Iudicone, Daniele; Ishii, Masao; Aumont, Olivier; Sarmiento, Jorge L.. |
| We evaluate the output from a widely used ocean carbon cycle model to identify the subduction and obduction (re-emergence) rates of anthropogenic carbon (Cant) for climatological conditions during the World Ocean Circulation Experiment (WOCE) era in 1995 using a new set of Lagrangian diagnostic tools. The principal scientific value of the Lagrangian diagnostics is in providing a new means to connect Cant re-emergence pathways to the relatively rapid renewal timescales of mode waters through the overturning circulation. Our main finding is that for this model with 2.04 PgC/yr of uptake of Cant via gas exchange, the subduction and obduction rates across the base of the mixed layer (MLbase) are 4.96 PgC/yr and 4.50 PgC/yr, respectively, which are twice as... |
| Tipo: Text |
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| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00395/50610/51323.pdf |
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| Dutheil, Cyril; Aumont, Olivier; Gorgues, Thomas; Lorrain, Anne; Bonnet, Sophie; Rodier, Martine; Dupouy, Cecile; Shiozaki, Takuhei; Menkes, Christophe. |
| Dinitrogen fixation is now recognized as one of the major sources of bio-available nitrogen in the ocean. Thus, N2 fixation sustains a significant part of the global primary production by supplying the most common limiting nutrient for phytoplankton growth. The Oligotrophy to UlTra-oligotrophy PACific Experiment (OUTPACE) improved the data coverage of the western tropical South Pacific, an area recently recognized as a hotspot of N2 fixation. This new development leads us to develop and test an explicit N2 fixation formulation based on the Trichodesmium physiology (the most studied nitrogen fixer) within a 3-D coupled dynamical–biogeochemical model (ROMS-PISCES). We performed a climatological numerical simulation that is able to reproduce the main physical... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00419/53042/53979.pdf |
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| Registros recuperados: 33 | |
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