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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... |
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| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00218/32919/31408.pdf |
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| Bouttes, N.; Paillard, D.; Roche, D. M.; Waelbroeck, C.; Kageyama, M.; Lourantou, A.; Michel, E.; Bopp, L.. |
| During the last termination (from similar to 18 000 years ago to similar to 9000 years ago), the climate significantly warmed and the ice sheets melted. Simultaneously, atmospheric CO2 increased from similar to 190 ppm to similar to 260 ppm. Although this CO2 rise plays an important role in the deglacial warming, the reasons for its evolution are difficult to explain. Only box models have been used to run transient simulations of this carbon cycle transition, but by forcing the model with data constrained scenarios of the evolution of temperature, sea level, sea ice, NADW formation, Southern Ocean vertical mixing and biological carbon pump. More complex models (including GCMs) have investigated some of these mechanisms but they have only been used to try... |
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| Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00214/32514/31004.pdf |
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| Roche, D. M.; Caley, T. |
| The (H2O)-O-18 stable isotope was previously introduced in the three coupled components of the earth system model iLOVECLIM: atmosphere, ocean and vegetation. The results of a long (5000 yr) pre-industrial equilibrium simulation are presented and evaluated against measurement of (H2O)-O-18 abundance in present-day water for the atmospheric and oceanic components. For the atmosphere, it is found that the model reproduces the observed spatial distribution and relationships to climate variables with some merit, though limitations following our approach are highlighted. Indeed, we obtain the main gradients with a robust representation of the Rayleigh distillation but caveats appear in Antarctica and around the Mediterranean region due to model limitation. For... |
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| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00383/49448/49926.pdf |
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| Caley, T.; Roche, D. M.; Waelbroeck, C.; Michel, E.. |
| We use the fully coupled atmosphere-ocean three-dimensional model of intermediate complexity iLOVECLIM to simulate the climate and oxygen stable isotopic signal during the Last Glacial Maximum (LGM, 21 000 years). By using a model that is able to explicitly simulate the sensor (delta O-18), results can be directly compared with data from climatic archives in the different realms. Our results indicate that iLOVECLIM reproduces well the main feature of the LGM climate in the atmospheric and oceanic components. The annual mean delta O-18 in precipitation shows more depleted values in the northern and southern high latitudes during the LGM. The model reproduces very well the spatial gradient observed in ice core records over the Greenland ice sheet. We observe... |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00297/40871/39916.pdf |
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| Zumaque, J.; Eynaud, Frederique; Zaragosi, S.; Marret, F.; Matsuzaki, K. M.; Kissel, C.; Roche, D. M.; Malaize, B.; Michel, E.; Billy, I.; Richter, T.; Palis, E.. |
| The rapid climatic variability characterising the Marine Isotopic Stage (MIS) 3 (similar to 60-30 cal ka BP) provides key issues to understand the atmosphere-ocean-cryosphere dynamics. Here we investigate the response of sea-surface paleoenvironments to the MIS3 climatic variability through the study of a high resolution oceanic sedimentological archive (core MD99-2281, 60 degrees 21' N; 09 degrees 27' W; 1197m water depth), retrieved during the MD114-IMAGES (International Marine Global Change Study) cruise from the southern part of the Faeroe Bank. This sector was under the proximal influence of European ice sheets (Fennoscandian Ice Sheet to the East, British Irish Ice Sheet to the South) during the last glacial and thus probably responded to the MIS3... |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00139/25060/23168.pdf |
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