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| Registros recuperados: 33 | |
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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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| 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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| Seferian, Roland; Berthet, Sarah; Yool, Andrew; Palmieri, Julien; Bopp, Laurent; Tagliabue, Alessandro; Kwiatkowski, Lester; Aumont, Olivier; Christian, James; Dunne, John; Gehlen, Marion; Ilyina, Tatiana; John, Jasmin G.; Li, Hongmei; Long, Matthew C; Luo, Jessica Y.; Nakano, Hideyuki; Romanou, Anastasia; Schwinger, Jorg; Stock, Charles; Santana-falcon, Yeray; Takano, Yohei; Tjiputra, Jerry; Tsujino, Hiroyuki; Watanabe, Michio; Wu, Tongwen; Wu, Fanghua; Yamamoto, Akitomo. |
| Purpose of Review The changes or updates in ocean biogeochemistry component have been mapped between CMIP5 and CMIP6 model versions, and an assessment made of how far these have led to improvements in the simulated mean state of marine biogeochemical models within the current generation of Earth system models (ESMs). Recent Findings The representation of marine biogeochemistry has progressed within the current generation of Earth system models. However, it remains difficult to identify which model updates are responsible for a given improvement. In addition, the full potential of marine biogeochemistry in terms of Earth system interactions and climate feedback remains poorly examined in the current generation of Earth system models. Increasing availability... |
| Tipo: Text |
Palavras-chave: Marine Biogeochemistry; CMIP5; CMIP6; Biogeochemistry-Climate Feedbacks; Model Performance. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00676/78827/81133.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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| 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... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00664/77572/79539.pdf |
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| Rodgers, K. B.; Aumont, Olivier; Fletcher, S. E. Mikaloff; Plancherel, Y.; Bopp, L.; De Boyer Montegut, Clement; Iudicone, D.; Keeling, R. F.; Madec, Gerard; Wanninkhof, R.. |
| Here we test the hypothesis that winds have an important role in determining the rate of exchange of CO2 between the atmosphere and ocean through wind stirring over the Southern Ocean. This is tested with a sensitivity study using an ad hoc parameterization of wind stirring in an ocean carbon cycle model, where the objective is to identify the way in which perturbations to the vertical density structure of the planetary boundary in the ocean impacts the carbon cycle and ocean biogeochemistry. Wind stirring leads to reduced uptake of CO2 by the Southern Ocean over the period 2000-2006, with a relative reduction with wind stirring on the order of 0.9 Pg C yr(-1) over the region south of 45 degrees S. This impacts not only the mean carbon uptake, but also the... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00211/32236/30684.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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| 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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| 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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| Radenac, Marie-helene; Jouanno, Julien; Tchamabi, Christine Carine; Awo, Mesmin; Bourles, Bernard; Arnault, Sabine; Aumont, Olivier. |
| Ocean color observations show semiannual variations in chlorophyll in the Atlantic cold tongue with a main bloom in boreal summer and a secondary bloom in December. In this study, ocean color and in situ measurements and a coupled physical-biogeochemical model are used to investigate the processes that drive this variability. Results show that the main phytoplankton bloom in July-August is driven by a strong vertical supply of nitrate in May-July, and the secondary bloom in December is driven by a shorter and moderate supply in November. The upper ocean nitrate balance is analyzed and shows that vertical advection controls the nitrate input in the equatorial euphotic layer and that vertical diffusion and meridional advection are key in extending and... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00623/73546/73808.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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| 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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| Ishii, Masao; Rodgers, Keith B.; Inoue, Hisayuki Y.; Toyama, Katsuya; Sasano, Daisuke; Kosugi, Naohiro; Ono, Hisashi; Enyo, Kazutaka; Nakano, Toshiya; Iudicone, Daniele; Blanke, Bruno; Aumont, Olivier; Feely, Richard A.. |
| Identifying ocean acidification and its controlling mechanisms is an important priority within the broader question of understanding how sustained anthropogenic CO2 emissions are harming the health of the ocean. Through extensive analysis of observational data products for ocean inorganic carbon, here we quantify the rate at which acidification is proceeding in the western tropical Pacific Warm Pool, revealing ‐0.0013 ±0.0001 yr‐1 for pH and ‐0.0083±0.0007 yr‐1 for the saturation index of aragonite for the years 1985‐2016. However, the mean rate of total dissolved inorganic carbon increase (+0.81 ±0.06 μmol kg‐1 yr‐1) sustaining acidification was ~20% slower than what would be expected if it were simply controlled by the rate of atmospheric CO2 increase... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00641/75337/76003.pdf |
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| Laufkotter, Charlotte; Vogt, Meike; Gruber, Nicolas; Aumont, Olivier; Bopp, Laurent; Doney, Scott C.; Dunne, John P.; Hauck, Judith; John, Jasmin G.; Lima, Ivan D.; Seferian, Roland; Volker, Christoph. |
| Accurate projections of marine particle export production (EP) are crucial for predicting the response of the marine carbon cycle to climate change, yet models show a wide range in both global EP and their responses to climate change. This is, in part, due to EP being the net result of a series of processes, starting with net primary production (NPP) in the sunlit upper ocean, followed by the formation of particulate organic matter and the subsequent sinking and remineralisation of these particles, with each of these processes responding differently to changes in environmental conditions. Here, we compare future projections in EP over the 21st century, generated by four marine ecosystem models under the high emission scenario Representative Concentration... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00600/71205/69576.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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| Ayata, S. -d.; Levy, Marina; Aumont, Olivier; Sciandra, Antoine; Sainte-marie, J.; Tagliabue, A.; Bernard, Olivier. |
| The aim of this study is to evaluate the consequences of accounting for variable Chl:C (chlorophyll:carbon) and C:N (carbon:nitrogen) ratios in the formulation of phytoplankton growth in biogeochemical models. We compare the qualitative behavior of a suite of phytoplankton growth formulations with increasing complexity: 1) a Redfield formulation (constant C:N ratio) without photo-acclimation (constant Chl:C ratio), 2) a Redfield formulation with diagnostic chlorophyll (variable and empirical Chl:C ratio), 3) a quota formulation (variable C:N ratio) with diagnostic chlorophyll, and 4) a quota formulation with prognostic chlorophyll (dynamic variable). These phytoplankton growth formulations are embedded in a simple marine ecosystem model in a 1D framework... |
| Tipo: Text |
Palavras-chave: Biogeochemical modeling; Phytoplankton; Photo-acclimation; Redfield ratio; Internal quota; BATS; Optimization; Micro-genetic algorithm. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00159/27071/25460.pdf |
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| Person, Roland; Aumont, Olivier; Levy, M.. |
| Iron is known to limit primary production in the Southern Ocean (SO). To cope with the lack of this micronutrient, diatoms, a dominant phytoplankton group in this oceanic region, have been shown in cultures to have developed an original adaptation strategy to maintain efficient growth rates despite very low cellular iron quotas, even in low light conditions. Using a global ocean biogeochemical model, we explored the consequences of this physiological adaptation for the biological pump and the seasonal variability of both surface chlorophyll concentrations and surface partial pressure of carbon dioxide (pCO(2)) in this key region for global climate. In the model, we implemented a low intracellular Fe:C requirement in the SO for diatoms uniquely. This... |
| Tipo: Text |
Palavras-chave: Southern Ocean; Diatoms; Physiological adaptation; Biological pump; PCO(2); Seasonal variability. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00673/78490/80817.pdf |
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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... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00192/30320/28789.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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| 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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| Registros recuperados: 33 | |
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