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| Penaud, Aurelie; Eynaud, F.; Voelker, A.; Kageyama, M.; Marret, F.; Turon, J. L.; Blamart, D.; Mulder, T.; Rossignol, L.. |
| New dinocyst analyses were conducted on core MD99-2339 retrieved from the central Gulf of Cadiz. Dinocyst and foraminiferal assemblages from this core are combined with existing data off SW Portugal and NW Morocco to investigate past hydrological and primary productivity regimes in the subtropical NE Atlantic Ocean over the last 30 ka. Our results have revealed highest upwelling intensity during Heinrich Stadial 1 (HS 1) and the Younger Dryas and weaker upwelling cells during the Last Glacial Maximum (LGM) and HS 2, off the SW Iberian and NW Moroccan margins. Similar assemblages between the Gulf of Cadiz and the NW Moroccan margin, and distinct species off Portugal, were observed during the cold climatic extremes that punctuated the last 30 ka. This... |
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| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00230/34125/32598.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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| 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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| Woillez, M.n; Levavasseur, G.; Daniau, A. -l.; Kageyama, M.; Urrego, D. H.; Sanchez Goni, Maria Fernanda; Hanquiez, Vincent. |
| The relationships between climate, vegetation and fires are a major subject of investigation in the context of climate change. In southern Africa, fire is known to play a crucial role in the existence of grasslands and Mediterranean-type biomes. Microcharcoal-based reconstructions of past fire activity in that region have shown a tight correlation between grass-fueled fires and the precessional cycle, with maximum fire activity during maxima of the climatic precession index. These changes have been interpreted as the result of changes in fuel load in response to precipitation changes in eastern southern Africa. Here we use the general circulation model IPSL_CM5A (Institut Pierre Simon Laplace Climate Model version 5A) and the dynamic vegetation model... |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00274/38485/36952.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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| 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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