Climate change projections using the IPSL-CM5 Earth System Model: from CMIP3 to CMIP5 Auteur(s) : Dufresne, J-l. Foujols, M-a. Denvil, S. Caubel, A. Marti, O. Aumont, Olivier Balkanski, Y. Bekki, S. Éditeur(s) : Springer Résumé : 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 presents an overview of the different model components and explains how they were coupled and used to simulate historical climate changes over the past 150 years and different scenarios of future climate change. A single version of the IPSL-CM5 model (IPSL-CM5A-LR) was used to provide climate projections associated with different socio-economic scenarios, including the different Representative Concentration Pathways considered by CMIP5 and several scenarios from the Special Report on Emission Scenarios considered by CMIP3. Results suggest that the magnitude of global warming projections primarily depends on the socio-economic scenario considered, that there is potential for an aggressive mitigation policy to limit global warming to about two degrees, and that the behavior of some components of the climate system such as the Arctic sea ice and the Atlantic Meridional Overturning Circulation may change drastically by the end of the twenty-first century in the case of a no climate policy scenario. Although the magnitude of regional temperature and precipitation changes depends fairly linearly on the magnitude of the projected global warming (and thus on the scenario considered), the geographical pattern of these changes is strikingly similar for the different scenarios. The representation of atmospheric physical processes in the model is shown to strongly influence the simulated climate variability and both the magnitude and pattern of the projected climate changes. Climate Dynamics (0930-7575) (Springer), 2013-05 , Vol. 40 , N. 9-10 , P. 2123-2165 Droits : The Author(s) 2013. This article is published with open access at Springerlink.com http://archimer.ifremer.fr/doc/00138/24966/23079.pdf DOI:10.1007/s00382-012-1636-1 http://archimer.ifremer.fr/doc/00138/24966/ | Partager Voir aussi Climate Climate change Climate projections Earth System Model CMIP5 CMIP3 Greenhouse gases Aerosols Carbon cycle Allowable emissions Télécharger |
Circulation and suspended sediment transport in a coral reef lagoon: The south-west lagoon of New Caledonia Auteur(s) : Ouillon, S. Douillet, Pascal Lefebvre, J. P. Le Gendre, Romain Jouon, Aymeric Bonneton, P. Fernandez, Chevillon, C. Éditeur(s) : Pergamon-elsevier Science Ltd Résumé : The south-west lagoon of New Caledonia is a wide semi-open coral reef lagoon bounded by an intertidal barrier reef and bisected by numerous deep inlets. This paper synthesizes findings from the 2000-2008 French National Program EC2CO-PNEC relative to the circulation and the transport of suspended particles in this lagoon. Numerical model development (hydrodynamic, fine suspended sediment transport, wind-wave, small-scale atmospheric circulation) allowed the determination of circulation patterns in the lagoon and the charting of residence time, the later of which has been recently used in a series of ecological studies. Topical studies based on field measurements permitted the parameterisation of wave set-up induced by the swell breaking on the reef barrier and the validation of a wind-wave model in a fetch-limited environment. The analysis of spatial and temporal variability of suspended matter concentration over short and long time-scales, the measurement of grain size distribution and the density of suspended matter (1.27 kg 1(-1)), and the estimation of erodibility of heterogeneous (sand/mud, terrigenous/biogenic) soft bottoms was also conducted. Aggregates were shown to be more abundant near or around reefs and a possible biological influence on this aggregation is discussed. Optical measurements enabled the quantification of suspended matter either in situ (monochromatic measurements) or remotely (surface spectral measurements and satellite observations) and provided indirect calibration and validation of a suspended sediment transport model. The processes that warrant further investigation in order to improve our knowledge of circulation and suspended sediment transport in the New Caledonia lagoon as well as in other coral reef areas are discussed, as are the relevance and reliability of the numerical models for this endeavour. Marine Pollution Bulletin (0025-326X) (Pergamon-elsevier Science Ltd), 2010 , Vol. 61 , N. 7-12 , P. 269-296 Droits : 2010 Elsevier Ltd All rights reserved. http://archimer.ifremer.fr/doc/00014/12526/9401.pdf DOI:10.1016/j.marpolbul.2010.06.023 http://archimer.ifremer.fr/doc/00014/12526/ | Partager Voir aussi Hydrodynamics Suspended sediment New Caledonia Coral reef lagoon Sediment Turbidity Resuspension Télécharger |