High-order <Emphasis Type="Italic">h</Emphasis>-adaptive discontinuous Galerkin methods for ocean modelling     

Paul-Emile Bernard  Nicolas Chevaugeon  Vincent Legat  Eric Deleersnijder  Jean-François Remacle 《Ocean Dynamics》2007,57(2):109-121

In this paper, we present an h-adaptive discontinuous Galerkin formulation of the shallow water equations. For a discontinuous Galerkin scheme using polynomials up to order , the spatial error of discretization of the method can be shown to be of the order of , where is the mesh spacing. It can be shown by rigorous error analysis that the discontinuous Galerkin method discretization error can be related to the amplitude of the inter-element jumps. Therefore, we use the information contained in jumps to build error metrics and size field. Results are presented for ocean modelling problems. A first experiment shows that the theoretical convergence rate is reached with the discontinuous Galerkin high-order h-adaptive method applied to the Stommel wind-driven gyre. A second experiment shows the propagation of an anticyclonic eddy in the Gulf of Mexico. An erratum to this article can be found at  相似文献   

Geophysical characterisation of karstic networks – Application to the Ouysse system (Poumeyssen,France)     

Roger Guérin  Jean-Michel Baltassat  Marie Boucher  Konstantinos Chalikakis  Pierre-Yves Galibert  Jean-François Girard  Valérie Plagnes  Rémi Valois 《Comptes Rendus Geoscience》2009,341(10-11):810-817

In the framework of the management of karstic aquifers, geophysical reconnaissance can be used to locate conduits and caves, and to characterise the surrounding limestone matrix. Suitable characterisation of heterogeneities in the karstic environment is, however, challenging for ground-based geophysical methods. The present article describes the results, and evaluates the response and accuracy of combined geophysical measurements carried out at the Poumeyssen test site in France, involving electrical resistivity imaging (ERI), magnetic resonance sounding (MRS), “mise-à-la-masse” electrical mapping, and seismic tomography. This site provides the opportunity to study a relatively wide, shallow, water-filled conduit whose location and shape are known from topographic work carried out by cave divers. Seismic and MRS provided the exact location and width of the conduit, to within a few meters. The seismic and electrical data suggest that the limestone medium surrounding the conduit is not homogeneous.  相似文献   

Protracted,coeval crust and mantle melting during Variscan late-orogenic evolution: U–Pb dating in the eastern French Massif Central     

Laurent  Oscar  Couzinié  Simon  Zeh  Armin  Vanderhaeghe  Olivier  Moyen  Jean-François  Villaros  Arnaud  Gardien  Véronique  Chelle-Michou  Cyril 《International Journal of Earth Sciences》2017,106(2):421-451

International Journal of Earth Sciences - The late stages of the Variscan orogeny are characterized by middle to lower crustal melting and intrusion of voluminous granitoids throughout the belt,...  相似文献   

Response of hurricane-type vortices to global warming as simulated by ARPEGE-Climat at high resolution   总被引：1，自引：0，他引：1  

Fabrice Chauvin  Jean-François Royer  Michel Déqué 《Climate Dynamics》2006,27(4):377-399

Atlantic hurricanes and their sensitivity to anthropogenic warming are investigated using very high (0.5°×0.5° over the Atlantic domain) resolution global simulations. The ARPEGE-Climat variable resolution grid demonstrates its usefulness in regional climate studies since resolution can be multiplied by a factor of 2.5 over the domain of interest compared to a uniform grid, for a similar computer cost. The question of hurricane characteristics dependence on anthropogenic warming is tackled trough the implementation of a tracking method. Changes in the total number, as well as locations, of hurricanes appear to depend more on sea surface temperature (SST) spatial patterns anomaly than Atlantic mean intensity, essentially through the change in large scale vertical wind shear. A uniform SST anomaly forcing produces increased and eastward shifted systems while a spatially contrasted anomaly leads to a decrease. Comparison between cyclogenesis density calculated from tracking or large scale combined variables (as a modified Gray parameter) brings some confidence in the use of the latter to investigate low resolution simulations. Mean hurricane dynamical characteristics are weakly changed by the warming but precipitation core and latent heat flux are enhanced in all scenarios.  相似文献   

Nouveaux éléments sur la structure et le fonctionnement hydrogéologique du plateau basaltique de l'Aubrac (Massif central,France). Première évaluation des potentialités en eau souterraine     

Pierre-Yves Bourlier  Patrick Lachassagne  Jean-François Desprats  Emmanuel Gille 《Comptes Rendus Geoscience》2005,337(7):663-673

In volcanic areas, the quality of the geological data at the various scales is of paramount importance for the estimation of aquifer potentialities and thus for groundwater exploitation. Geological and hydrogeological investigation (synthesis of existing data, field geological observations, reconstruction of the infra-volcanic morphology, stream gauging, field hydrogeology, etc.) have been performed on the 450-km² Aubrac basaltic plateau (Massif Central, France). These results allow us to specify the hydrological structure and functioning of this volcanic plateau that were quite unknown before. It is mainly constituted by the piling up of lava flows resting on a plutonic and metamorphic substratum. This volcanic unit constitutes an aquifer of regional importance whose groundwater resources are currently underexploited. These results allow us to delineate zones and strategies for priority hydrogeological prospecting. To cite this article: P.-Y. Bourlier et al., C. R. Geoscience 337 (2005).  相似文献   

Climate simulation of the twenty-first century with interactive land-use changes   总被引：5，自引：0，他引：5  

Aurore Voldoire  Bas Eickhout  Michiel Schaeffer  Jean-François Royer  Fabrice Chauvin 《Climate Dynamics》2007,29(2-3):177-193

To include land-use dynamics in a general circulation model (GCM), the physical system has to be linked to a system that represents socio-economy. This issue is addressed by coupling an integrated assessment model, IMAGE2.2, to an ocean–atmosphere GCM, CNRM-CM3. In the new system, IMAGE2.2 provides CNRM-CM3 with all the external forcings that are scenario dependent: greenhouse gas (GHGs) concentrations, sulfate aerosols charge and land cover. Conversely, the GCM gives IMAGE changes in mean temperature and precipitation. With this new system, we have run an adapted scenario of the IPCC SRES scenario family. We have chosen a single scenario with maximum land-use changes (SRES A2), to illustrate some important feedback issues. Even in this two-way coupled model set-up, land use in this scenario is mainly driven by demographic and agricultural practices, which overpowers a potential influence of climate feedbacks on land-use patterns. This suggests that for scenarios in which socio-economically driven land-use change is very large, land-use changes can be incorporated in GCM simulations as a one-way driving force, without taking into account climate feedbacks. The dynamics of natural vegetation is more closely linked to climate but the time-scale of changes is of the order of a century. Thus, the coupling between natural vegetation and climate could generate important feedbacks but these effects are relevant mainly for multi-centennial simulations.  相似文献   

African monsoon teleconnections with tropical SSTs: validation and evolution in a set of IPCC4 simulations     

Mathieu Joly  Aurore Voldoire  Hervé Douville  Pascal Terray  Jean-François Royer 《Climate Dynamics》2007,29(1):1-20

A set of 12 state-of-the-art coupled ocean-atmosphere general circulation models (OAGCMs) is explored to assess their ability to simulate the main teleconnections between the West African monsoon (WAM) and the tropical sea surface temperatures (SSTs) at the interannual to multi-decadal time scales. Such teleconnections are indeed responsible for the main modes of precipitation variability observed over West Africa and represent an interesting benchmark for the models that have contributed to the fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC4). The evaluation is based on a maximum covariance analysis (MCA) applied on tropical SSTs and WAM rainfall. To distinguish between interannual and multi-decadal variability, all datasets are partitioned into low-frequency (LF) and high-frequency (HF) components prior to analysis. First applied to HF observations, the MCA reveals two major teleconnections. The first mode highlights the strong influence of the El Niño Southern Oscillation (ENSO). The second mode reveals a relationship between the SST in the Gulf of Guinea and the northward migration of the monsoon rainbelt over the West African continent. When applied to HF outputs of the twentieth century IPCC4 simulations, the MCA provides heterogeneous results. Most simulations show a single dominant Pacific teleconnection, which is, however, of the wrong sign for half of the models. Only one model shows a significant second mode, emphasizing the OAGCMs’ difficulty in simulating the response of the African rainbelt to Atlantic SST anomalies that are not synchronous with Pacific anomalies. The LF modulation of these HF teleconnections is then explored through running correlations between expansion coefficients (ECs) for SSTs and precipitation. The observed time series indicate that both Pacific and Atlantic teleconnections get stronger during the twentieth century. The IPCC4 simulations of the twentieth and twenty-first centuries do not show any significant change in the pattern of the teleconnections, but the dominant ENSO teleconnection also exhibits a significant strengthening, thereby suggesting that the observed trend could be partly a response to the anthropogenic forcing. Finally, the MCA is also applied to the LF data. The first observed mode reveals a well-known inter-hemispheric SST pattern that is strongly related to the multi-decadal variability of the WAM rainfall dominated by the severe drying trend from the 1950s to the 1980s. Whereas recent studies suggest that this drying could be partly caused by anthropogenic forcings, only 5 among the 12 IPCC4 models capture some features of this LF coupled mode. This result suggests the need for a more detailed validation of the WAM variability, including a dynamical interpretation of the SST–rainfall relationships.  相似文献   

Distribution of silver in mussels and oysters along the French coasts: data from the national monitoring program     

Chiffoleau JF  Auger D  Roux N  Rozuel E  Santini A 《Marine pollution bulletin》2005,50(12):1719-1723

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Les surfaces boisées à l'échelle de la planète : usages conjoints pour la séquestration du carbone et la production d'énergie     

Anne Prieur  Jean-François Bonnet  Michel Combarnous 《Comptes Rendus Geoscience》2004,336(15):1323-1335

The role of forest ecosystems in the regulation of greenhouse effect at the global scale is developed here, from two points of view, sometimes considered as opposed: carbon storage and wood production for energy. A nomenclature is proposed to understand all the various mechanisms implied in carbon storage. A comparison is made between the effects on carbon emissions of storage alone and storage with wood fuel production. Use of wood energy is proved to be a ‘bonus’ that could optimise, in the middle and long terms, the use of fossil fuel reserves. To cite this article: A. Prieur et al., C. R. Geoscience 336 (2004).  相似文献   

Enregistrements sismologiques de l'explosion sur le site de l'usine AZF (Toulouse,France)Seismological records of an explosion at the AZF chemical complex in Toulouse,France     

Annie Souriau  Matthieu Sylvander  Valérie Maupin  Jean-François Fels  Alexis Rigo 《Comptes Rendus Geoscience》2002,334(3):155-161

This study presents a detailed analysis of the seismic records of a strong explosion that occurred on 21 September 2001 at a chemical complex located south of Toulouse, France, and provoked important damages. The explosion, which is equivalent to a 3.4 magnitude earthquake, has been recorded at most of the stations of the National Seismological Network, as well as at a station under test at the ‘Observatoire Midi-Pyrénées’, 4.2 km away from the epicentre. The main seismic phases are interpreted using the known crustal structures, and a modelling with synthetic seismograms is performed. To cite this article: A. Souriau et al., C. R. Geoscience 334 (2002) 155–161.  相似文献