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| Schmittner, A.; Gruber, N.; Mix, A. C.; Key, R. M.; Tagliabue, A.; Westberry, T. K.. |
| Analysis of observations and sensitivity experiments with a new three-dimensional global model of stable carbon isotope cycling elucidate processes that control the distribution of delta C-13 of dissolved inorganic carbon (DIC) in the contemporary and preindustrial ocean. Biological fractionation and the sinking of isotopically light delta C-13 organic matter from the surface into the interior ocean leads to low delta C-13(DIC) values at depths and in high latitude surface waters and high values in the upper ocean at low latitudes with maxima in the subtropics. Air-sea gas exchange has two effects. First, it acts to reduce the spatial gradients created by biology. Second, the associated temperature-dependent fractionation tends to increase (decrease) delta... |
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| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00292/40354/38909.pdf |
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| Mtshali, T.n.; Horsten, N.r.; Thomalla, S.j.; Ryan‐keogh, T.j.; Nicholson, S.‐a.; Roychoudhury, A.n.; Bucciarelli, Eva; Sarthou, Geraldine; Tagliabue, A.; Monteiro, P.m.s.. |
| Seasonal progression of dissolved iron (DFe) concentrations in the upper water column were examined during four occupations in the Atlantic sector of the Southern Ocean. DFe inventories from euphotic and aphotic reservoirs decreased progressively from July to February, while dissolved inorganic nitrogen (DIN) decreased from July to January with no significant change between January and February. Results suggest that between July and January, DFe loss from both euphotic and aphotic reservoirs were predominantly in support of phytoplankton growth (Iron to carbon (Fe:C) uptake ratio of 16±3 μmol mol‐1) highlighting the importance of the “winter DFe‐reservoir” for biological uptake. During January to February, excess loss of DFe relative to DIN (Fe:C uptake... |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00487/59914/63095.pdf |
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| Tagliabue, A.; Bopp, L.; Roche, D. M.; Bouttes, N.; Dutay, J. -c.; Alkama, R.; Kageyama, M.; Michel, E.; Paillard, D.. |
| We use a state-of-the-art ocean general circulation and biogeochemistry model to examine the impact of changes in ocean circulation and biogeochemistry in governing the change in ocean carbon-13 and atmospheric CO2 at the last glacial maximum (LGM). We examine 5 different realisations of the ocean's overturning circulation produced by a fully coupled atmosphere-ocean model under LGM forcing and suggested changes in the atmospheric deposition of iron and phytoplankton physiology at the LGM. Measured changes in carbon-13 and carbon-14, as well as a qualitative reconstruction of the change in ocean carbon export are used to evaluate the results. Overall, we find that while a reduction in ocean ventilation at the LGM is necessary to reproduce carbon-13 and... |
| Tipo: Text |
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| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00218/32919/31408.pdf |
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| Chever, Fanny; Bucciarelli, Eva; Sarthou, G.; Speich, Sabrina; Arhan, Michel; Penven, Pierrick; Tagliabue, A.. |
| [1] Distributions of total dissolvable iron (TDFe; unfiltered), dissolved iron (DFe; 0.2 mu m filtered), and soluble iron (SFe; 0.02 mu m filtered) were investigated during the BONUS-GoodHope cruise in the Atlantic sector of the Southern Ocean (34 degrees S/17 degrees E-57 degrees S/0 degrees, February-March 2008). In the mixed layer, mean values of 0.43 +/- 0.28 and 0.22 +/- 0.18 nmol L-1 were measured for TDFe and DFe, respectively. In deeper waters, TDFe and DFe concentrations were 1.07 +/- 0.68 and 0.52 +/- 0.30 nmol L-1, respectively. DFe concentrations decreased from the north (subtropical waters) to the south (Weddell Sea Gyre). In the subtropical domain, dusts coming from Patagonia and southern Africa and inputs from the African continental margin... |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00017/12808/9763.pdf |
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| Aumont, O.; Ethe, C.; Tagliabue, A.; Bopp, L.; Gehlen, M.. |
| PISCES-v2 (Pelagic Interactions Scheme for Carbon and Ecosystem Studies volume 2) is a biogeochemical model which simulates the lower trophic levels of marine ecosystems (phytoplankton, microzooplankton and meso-zooplankton) and the biogeochemical cycles of carbon and of the main nutrients (P, N, Fe, and Si). The model is intended to be used for both regional and global configurations at high or low spatial resolutions as well as for short-term (seasonal, interannual) and long-term (climate change, paleoceanography) analyses. There are 24 prognostic variables (tracers) including two phytoplankton compartments (diatoms and nanophytoplankton), two zooplankton size classes (micro-zooplankton and mesozooplankton) and a description of the carbonate chemistry.... |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00288/39908/38456.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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| 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... |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00591/70270/68330.pdf |
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| Mariotti, V.; Bopp, L.; Tagliabue, A.; Kageyama, M.; Swingedouw, D.. |
| Marine sediments records suggest large changes in marine productivity during glacial periods, with abrupt variations especially during the Heinrich events. Here, we study the response of marine biogeochemistry to such an event by using a biogeochemical model of the global ocean (PISCES) coupled to an ocean-atmosphere general circulation model (IPSL-CM4). We conduct a 400-yr-long transient simulation under glacial climate conditions with a freshwater forcing of 0.1 Sv applied to the North Atlantic to mimic a Heinrich event, alongside a glacial control simulation. To evaluate our numerical results, we have compiled the available marine productivity records covering Heinrich events. We find that simulated primary productivity and organic carbon export... |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00266/37695/35833.pdf |
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