Simulation des changements climatiques au cours du XXI^e siècle incluant l'ozone stratosphériqueSimulation of climate changes during the 21st century including stratospheric ozone     

Jean-François Royer  Daniel Cariolle  Fabrice Chauvin  Michel Déqué  Hervé Douville  Rong-Ming Hu  Serge Planton  Annie Rascol  Jean-Louis Ricard  David Salas Y Melia  Florence Sevault  Pascal Simon  Samuel Somot  Sophie Tyteca  Laurent Terray  Sophie Valcke 《Comptes Rendus Geoscience》2002,334(3):147-154

Two climate simulations of 150 years, performed with a coupled ocean/sea-ice/atmosphere model including stratospheric ozone, respectively with and without heterogeneous chemistry, simulate the tropospheric warming associated with an increase of the greenhouse effect of carbon dioxide and other trace gases since 1950 and their impact on sea–ice extent, as well as the stratospheric cooling and its impact on ozone concentration. The scenario with heterogeneous chemistry reproduces the formation of the ozone hole over the South Pole from the 1970s and its deepening until the present time, and shows that the ozone hole should progressively fill during the coming decades. To cite this article: J.-F. Royer et al., C. R. Geoscience 334 (2002) 147–154.  相似文献   

Significance of a combined approach for replacement stones in the heritage buildings’ conservation frame     

Olivier Rozenbaum  Luc Barbanson  Fabrice Muller  Ary Bruand   《Comptes Rendus Geoscience》2008,340(6):345-355

Stone substitution is a conventional operation during heritage buildings’ restoration, but becomes problematic for architects and restorers when the quarry is mined out. The compatibility of the substitution stones with the original ones has been for long mainly based on the aesthetical aspect, this resulting too often in a patchwork of original and substitution stones with different patina after several years because of differences of properties. In this study, the objective is to show how substitution stones can be selected by combining aesthetic criteria and stones properties that are relevant for analyzing their compatibility. A couple of French limestones with their potential substitution stones were selected for the study. Our results showed that potential substitution stones selected on their aesthetic criteria require to be rejected because of their differences of physical properties. On the other hand, our results showed also the possibility to select substitution stones with satisfactory aesthetic aspect and properties that enable to expect a satisfactory compatibility with the original stone.  相似文献   

Tracking past mining activity using trace metals,lead isotopes and compositional data analysis of a sediment core from Longemer Lake,Vosges Mountains,France     

Anne-Lise Mariet  Fabrice Monna  Frédéric Gimbert  Carole Bégeot  Christophe Cloquet  Simon Belle  Laurent Millet  Damien Rius  Anne-Véronique Walter-Simonnet 《Journal of Paleolimnology》2018,60(3):399-412

A 157-cm-long sediment core from Longemer Lake in the Vosges Mountains of France spans the past two millennia and was analyzed for trace metal content and lead isotope composition. Trace metal accumulation rates highlight three main input phases: Roman Times (cal. 100 BC–AD 400), the Middle Ages (cal. AD 1000–1500), and the twentieth century. Atmospheric contamination displays a pattern that is similar to that seen in peat bogs from the region, at least until the eighteenth century. Thereafter, the lake sediment record is more precise than peat records. Some regional mining activity, such as that in archaeologically identified eighteenth-century mining districts, was detected from the lead isotope composition of sediment samples. Compositional data analysis, using six trace metals (silver, arsenic, cadmium, copper, lead and zinc), enabled us to distinguish between background conditions, periods of mining, and of other anthropogenic trace metal emissions, such as the recent use of leaded gasoline.  相似文献   

Shear zones in porous sand: Insights from ring-shear experiments and naturally deformed sandstones   总被引：2，自引：1，他引：2  

Anita Torabi  Alvar Braathen  Fabrice Cuisiat  Haakon Fossen 《Tectonophysics》2007,437(1-4):37-50

In a high-resolution small-scale seismic experiment we investigated the shallow structure of the Wadi Araba fault (WAF), the principal fault strand of the Dead Sea Transform System between the Gulf of Aqaba/Eilat and the Dead Sea. The experiment consisted of 8 sub-parallel 1 km long seismic lines crossing the WAF. The recording station spacing was 5 m and the source point distance was 20 m. The first break tomography yields insight into the fault structure down to a depth of about 200 m. The velocity structure varies from one section to the other which were 1 to 2 km apart, but destinct velocity variations along the fault are visible between several profiles. The reflection seismic images show positive flower structures and indications for different sedimentary layers at the two sides of the main fault. Often the superficial sedimentary layers are bent upward close to the WAF. Our results indicate that this section of the fault (at shallow depths) is characterized by a transpressional regime. We detected a 100 to 300 m wide heterogeneous zone of deformed and displaced material which, however, is not characterized by low seismic velocities at a larger scale. At greater depth the geophysical images indicate a blocked cross-fault structure. The structure revealed, fault cores not wider than 10 m, are consistent with scaling from wear mechanics and with the low loading to healing ratio anticipated for the fault.  相似文献   

The northwestern Argentina Tarija Basin: Stratigraphy, depositional systems, and controlling factors in a glaciated basin   总被引：1，自引：0，他引：1  

Daniel Starck  Cecilia del Papa   《Journal of South American Earth Sciences》2006,22(3-4):169

The Tarija Basin, shared by Bolivia and Argentina, was subjected to glacial conditions during the Late Carboniferous and Early Permian. The Macharetí and Mandiyutí groups deposited during these times record in their facies advances and retreats of the Gondwanan ice cap. The lithostratigraphic subdivision of these groups presents stages with minor glacial influence in the basal formations of each group (Tupambi and Escarpment formations), whereas in the upper units, glacially related deposition prevails (Tarija and San Telmo formations). Typical facies deposited in relation to glacial settings are diamictites and mudstones mainly related to proglacial, lacustrine environments. During the stages of main ice retreat, deposition was dominated by fluvial and deltaic sandstones. Significant erosion and deep valley incision characterize the basal surfaces of both groups. Conversely, the stratigraphic surface that separates the sandy formations from the overlying diamictites tends to be rather flat. The dynamics of the glacial cap are not only reflected in the facies distribution but also were a key factor in creating accommodation space; the changes in the glacial-driven subsidence linked to the advance and retreat of the ice were its main control.  相似文献   

Interannual variability and predictability of African easterly waves in a GCM     

Fabrice Chauvin  Jean-François Royer  Hervé Douville 《Climate Dynamics》2005,24(5):523-544

The interannual variability of African Easterly Waves (AEWs) is assessed with the help of spatio-temporal spectral analysis (STSA) and complex empirical orthogonal functions methods applied to the results of ten-member multiyear ensemble simulations. Two sets of experiments were conducted with the Météo-France ARPEGE-Climat GCM, one with interactive soil moisture (control), and the other with soil moisture relaxed towards climatological monthly means calculated from the control. Composites of Soudano–Sahelian AEWs were constructed and associated physical processes and dynamics were studied in the frame of the waves. It is shown that the model is able to simulate realistically some interannual variability in the AEWs, and that this dynamical aspect of the West African climate is potentially predictable (i.e. signal can be extracted from boundary conditions relatively to internal error of the GCM), especially along the moist Guinean coast. Compared with ECMWF 15-year reanalysis (ERA15), the maximum activity of AEWs is located too far to the South and is somewhat too zonal, but the main characteristics of the waves are well represented. The major impact of soil moisture relaxation in the GCM experiments is to reduce the seasonal potential predictability of AEWs over land by enhancing their internal variability.  相似文献   

Electrical conductivity of polycrystalline Mg(OH)<Subscript>2</Subscript> at 2 GPa: effect of grain boundary hydration–dehydration     

Julien Gasc  Fabrice Brunet  Nikolai Bagdassarov  Victor Morales-Flórez 《Physics and Chemistry of Minerals》2011,38(7):543-556

The effect of intergranular water on the conductivity of polycrystalline brucite, Mg(OH)₂, was investigated using impedance spectroscopy at 2 GPa, during consecutive heating–cooling cycles in the 298–980 K range. The grain boundary hydration levels tested here span water activities from around unity (wet conditions) down to 10⁻⁴ (dry conditions) depending on temperature. Four orders of magnitude in water activity result in electrical conductivity variations for about 6–7 orders of magnitude at 2 GPa and room temperature. Wet brucite samples containing, initially, about 18 wt% of evaporable water (i.e. totally removed at temperatures below 393 K in air), display electrical conductivity values above 10⁻²–10⁻³ S/m. A.C. electrical conductivity as a function of temperature follows an Arrhenius behaviour with an activation energy of 0.11 eV. The electrical conductivity of the same polycrystalline brucite material dried beforehand at 393 K (dry conditions) is lower by about 5–6 orders of magnitude at room temperature and possesses an activation energy of 0.8–0.9 eV which is close to that of protonic diffusion in (001) brucitic planes. Above ca. 873 K, a non-reversible conductivity jump is observed which is interpreted as a water transfer from mineral bulk to grain boundaries (i.e. partial dehydration). Cooling of such partially dehydrated sample shows electrical conductivities much higher than those of the initially dry sample by 4 orders of magnitude at 500 K. Furthermore, the corresponding activation energy is decreased by a factor of about four (i.e. 0.21 eV). Buffering of the sample at low water activity has been achieved by adding CaO or MgO, two hygroscopic compounds, to the starting material. Then, sample conductivities reached the lowest values encountered in this study with the activation energy of 1.1 eV. The strong dependency of the electrical conductivity with water activity highlights the importance of the latter parameter as a controlling factor of diffusion rates in natural processes where water availability and activity may vary grandly. Water exchange between mineral bulk and mineral boundary suggests that grain boundary can be treated as an independent phase in dehydroxylation reactions.  相似文献   

The use of EPROM memories with a conventional tide-well gauge to record short period seiches     

P. Ottonello  L. Papa 《Continental Shelf Research》1982,1(1):117-121

A low cost electronic apparatus is presented, which increases considerably the useful frequency range of mechanical floating type tide-gauges. The detection and the measurement of sea level oscillations in the range of 5 to 60 min is then possible. In a preliminary application, the presence in the Gulf of Genoa of shelf oscillations, predicted by a numerical model, have been detected.  相似文献   

A numerical computation of a seiche oscillation of the Ligurian Sea     

L. Papa 《Geophysical Journal International》1983,75(3):659-667

Summary. A depth-integrated hydrodynamical model of the Ligurian Sea has shown the existence of a seiche motion of the basin with a 5.8 hr period. This result was obtained by using an open model boundary from Nice, France to Calvi, Corsica and an artificial solid boundary from Corsica to Elba and the Italian mainland. This seiche has been identified with a 5.8 hr period wave which was revealed in the sea-level variations at Genoa and Imperia.  相似文献   

A study of wave refraction in the northern Ligurian Sea     

L. De Floriani  L. Papa 《Advances in water resources》1983,6(2):121-123

Two mathematical models of surface gravity wave refraction were applied to a coastal area of the northern Ligurian Sea. A series of refraction patterns was computed by means of wave data recorded at a moored platform operating 1.5 miles off the harbour of Genoa. The numerical calculations provided an effect of wave energy concentration near Chiavari and Lavagna where coastal structures and beaches are often damaged during storm surges.  相似文献