High-pressure polymorphism of FeO? An alternative interpretation and its implications for the Earth's core     

Lin-gun Liu  Pouyan Shen  William A. Bassett 《Geophysical Journal International》1982,70(1):57-66

Summary. It has been reported that no stoichiometric FeO can be formed at temperatures above about 600°C regardless of pressure. The stoichiometry of Fe _X O quenched from static high pressure and temperature experiments appears to decrease with increasing pressure in the range 100–300kbar. On the basis of these observations, we have re-interpreted the recent shock results on Fe_0.94O, and have found that the Hugoniot data can be reasonable interpreted by the same shift in stoichiometry as observed in the static high-pressure experiments instead of a first-order transformation as proposed. If oxygen is assumed to be the light component of the outer core, the outer core can be chemically homogeneous only if the stoichiometry of Fe _X O decreases with increasing pressure. A constant stoichiometry would demand that the oxygen content decreases by a factor of 2 from the top to the bottom of the outer core. A chemically homogeneous outer core is consistent with a convecting outer core.  相似文献   

Late Pleistocene (MIS 3–4) climate inferred from micromammal communities and δO of rodents from Les Pradelles,France     

Aurélien Royer  Christophe Lécuyer  Sophie Montuire  Gilles Escarguel  François Fourel  Alan Mann  Bruno Maureille 《Quaternary Research》2013

The middle Paleolithic stratigraphic sequence of Les Pradelles (Charente, France) spans from the end of Marine Isotope Stage (MIS) 4 until the middle of MIS 3. Micromammal remains are present in all the stratigraphic levels, offering a rare opportunity to address the questions of both environmental and climatic fluctuations throughout this period. Climate modes were studied through the taphonomy, biodiversity and oxygen isotope compositions of phosphate (δ¹⁸O_p) from 66 samples of rodent tooth enamel. The δ¹⁸O_p values from the lower sedimentary levels provide summer mean air temperatures of 19 ± 2°C (level 2/1) and of 16 ± 2°C (levels 2A, 2B and 4A). Within the middle of sequence (level 4B), a paleobiodiversity change can be identified with an increase of Dicrostonyx torquatus, which is associated with the largest amplitude in δ¹⁸O_p values and the highest maximal δ¹⁸O_p values. At the top of the sequence (level 5-2), a biodiversity change is observed with the increase of Microtus arvalis, but without any change in δ¹⁸O_p values. The association of cold rodent species with unexpected high and large amplitudes in the δ¹⁸O_p values of their teeth, possibly indicative of aridity, suggests their deposition during a Heinrich event.  相似文献   

TESSIN VISLab—laboratory for scientific visualization     

Lars Bilke  Thomas Fischer  Carolin Helbig  Charlotte Krawczyk  Thomas Nagel  Dmitri Naumov  Sebastian Paulick  Karsten Rink  Agnes Sachse  Sophie Schelenz  Marc Walther  Norihiro Watanabe  Björn Zehner  Jennifer Ziesch  Olaf Kolditz 《Environmental Earth Sciences》2014,72(10):3881-3899

Scientific visualization is an integral part of the modeling workflow, enabling researchers to understand complex or large data sets and simulation results. A high-resolution stereoscopic virtual reality (VR) environment further enhances the possibilities of visualization. Such an environment also allows collaboration in work groups including people of different backgrounds and to present results of research projects to stakeholders or the public. The requirements for the computing equipment driving the VR environment demand specialized software applications which can be run in a parallel fashion on a set of interconnected machines. Another challenge is to devise a useful data workflow from source data sets onto the display system. Therefore, we develop software applications like the OpenGeoSys Data Explorer, custom data conversion tools for established visualization packages such as ParaView and Visualization Toolkit as well as presentation and interaction techniques for 3D applications like Unity. We demonstrate our workflow by presenting visualization results for case studies from a broad range of applications. An outlook on how visualization techniques can be deeply integrated into the simulation process is given and future technical improvements such as a simplified hardware setup are outlined.  相似文献   

How basin model results enable the study of multi-layer aquifer response to pumping: the Paris Basin, France     

Camille Contoux  Sophie Violette  Raffaella Vivona  Patrick Goblet  Delphine Patriarche 《Hydrogeology Journal》2013,21(3):545-557

The Albian aquifer of the Paris Basin (France) has been exploited since 1841 and shows drastic drawdown. A three-dimensional (3D) groundwater flow model is used to study the hydrodynamic response of the multi-layered aquifers to pumping activity in the Albian, at basin scale over 167 years. This 3D flow model uses geometry and hydrodynamic parameter distributions that are inherited from a genetic approach through basin modelling, the basin model creating a geometric pattern of hydrodynamic properties constrained by geological history. The paper aims to promote the use of the basin model approach (long time scale, 248 Ma) for the study of deep-aquifer response to anthropogenic perturbation (short time scale, 167 years) in situations for which hydrodynamic data are scarce but geological data are numerous. The results show that parameter distribution is insufficient to reproduce the Albian aquifer behaviour, notably highlighting a different meaning of the specific storage coefficient between basin modelling and groundwater-flow modelling. Dividing the storage coefficient by 100 and including available transmissivity data significantly improved the model/data comparison. The potential impact on a deep aquitard is then discussed. This study sheds light on the advantages and limitations of the basin model approach for groundwater-flow modelling in 3D.  相似文献   

Antenna-coupled arrays of NbSi micro-bolometers     

Aur��lien Bideaud  Benoit Belier  Alain Benoit  Laurent Berg��  Philippe Camus  Sophie Collin  Louis Dumoulin  Christian Hoffmann  Stefanos Marnieros  Alessandro Monfardini 《Experimental Astronomy》2011,32(2):179-191

Microbolometers are at present the most sensitive detectors for mm and sub-mm Astronomy. They are in use in most of the present instruments in that bandwidth. We have developed filled arrays of NbSi-based planar antenna coupled microbolometers. The fabrication details are given, together with characterization of the NbSi thermometers and optical results. The optical performances are potentially good for ground-based mm-wave astronomy applications, while the overall detectors performances are limited by low-frequency excess noise in the thermometric NbSi high-impedance sensors (Anderson insulator).  相似文献   

Analytical solutions for co- and counter-current imbibition of sorbing, dispersive solutes in immiscible two-phase flow     

Karen Sophie Schmid  Sebastian Geiger  Kenneth Stuart Sorbie 《Computational Geosciences》2012,16(2):351-366

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A kernel spatial density estimation allowing for the analysis of spatial clustering. Application to Monsoon Asia Drought Atlas data     

Sophie Dabo-Niang  Leila Hamdad  Camille Ternynck  Anne-Françoise Yao 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(8):2075-2099

A nonparametric density estimate that incorporates spatial dependency has not been studied in the literature. In this article, we propose a new spatial density estimator that depends on two kernels: one controls the distance between observations while the other controls the spatial dependence structure. The uniform almost sure convergence of the density estimate is established with the rate of convergence. The consistency of the mode of this kernel density is also studied. Then a spatial hierarchical unsupervised clustering algorithm based on the mode estimate is presented. Some simulations as well as an application to the Monsoon Asia Drought Atlas data illustrate the efficiency of our algorithm, and a comparison of the spatial structures of these data detected by the density estimate and clustering algorithm are done.  相似文献   

Impact of the configuration of stretching and ocean–atmosphere coupling on tropical cyclone activity in the variable-resolution GCM ARPEGE     

Anne Sophie Daloz  Fabrice Chauvin  Frank Roux 《Climate Dynamics》2012,39(9-10):2343-2359

This study starts by investigating the impact of the configuration of the variable-resolution atmospheric grid on tropical cyclone (TC) activity. The French atmospheric general circulation model ARPEGE, the grid of which is rotated and stretched over the North Atlantic basin, was used with prescribed sea surface temperatures. The study clearly shows that changing the position of the stretching pole strongly modifies the representation of TC activity over the North Atlantic basin. A pole in the centre of the North Atlantic basin provides the best representation of the TC activity for this region. In a second part, the variable-resolution climate model ARPEGE is coupled with the European oceanic global climate model NEMO in order to study the impact of ocean–atmosphere coupling on TC activity over the North Atlantic basin. Two pre-industrial runs, a coupled simulation and a simulation forced by the sea surface temperatures from the coupled one, are compared. The results show that the coupled simulation is more active in the Caribbean Sea and the Gulf of Mexico while the forced simulation is more active over eastern Florida and the eastern Atlantic. The difference in the distribution of TC activity is certainly linked with the location of TC genesis. In the forced simulation, tropical cyclogenesis is closer to the west African coast than in the coupled simulation. Moreover, the difference in TC activity over the eastern Atlantic seems to be related to two different mechanisms: the difference in African easterly wave activity over the west of Africa and the cooling produced, in the coupled simulation, by African easterly waves over the eastern Atlantic. Finally, the last part studies the impact of changing the frequency of ocean–atmosphere coupling on Atlantic TC activity. Increasing the frequency of coupling decreases the density of TC activity over the North Atlantic basin. However, it does not modify the spatial distribution of the TC activity. TC rainfalls are decreased by 8?% in the high frequency coupled run.  相似文献   

A New Interlaboratory Characterisation of Silicon,Rare Earth Elements and Twenty‐Two Other Trace Element Concentrations in the Natural River Water Certified Reference Material SLRS‐6 (NRC‐CNRC)     

Delphine Yeghicheyan  Dominique Aubert  Martine Bouhnik‐Le Coz  Jrme Chmeleff  Sophie Delpoux  Irina Djouraev  Guy Granier  Franois Lacan  Jean‐Luc Piro  Tristan Rousseau  Christophe Cloquet  Aurlie Marquet  Christophe Menniti  Catherine Pradoux  Rmi Freydier  Emmanoel Vieira da Silva‐Filho  Krzysztof Suchorski 《Geostandards and Geoanalytical Research》2019,43(3):475-496

The natural river water reference material SLRS‐6 (NRC‐CNRC) is the newest batch of a quality control material routinely used in many international environmental laboratories. This work presents a nine‐laboratory compilation of measurements of major and trace element concentrations and their related uncertainties, unavailable in the NRC‐CNRC certificate (B, Cs, Li, Ga, Ge, Hf, Nb, P, Rb, Rh, Re, S, Sc, Se, Si, Sn, Th, Ti, Tl, W, Y, Y, Zr and REEs). Measurements were mostly made using inductively coupled plasma‐mass spectrometry. The results are compared with equivalent data for the last batch of the material, SLRS‐5, measured simultaneously with SLRS‐6 in this study. In general, very low concentrations, close to the quantification limits, were found in the new batch. The Sr isotopic ratio is also reported.  相似文献   

Thermal anomalies and paleoclimatic diffusive and advective phenomena: example of the Anglo-Paris Basin,northern France     

Jacques Dentzer  Sophie Violette  Simon Lopez  Dominique Bruel 《Hydrogeology Journal》2017,25(7):1951-1965

This study is the first quantification of the combined impact of diffusive and advective paleoclimatic phenomena to explain the weak vertical thermal flux anomaly in the upper part of the Anglo-Paris intracratonic sedimentary basin in northern France. The aim of the research is to understand the mechanisms at the origin of the thermal flux anomaly at the level of the Meso-Cenozoic sediment pile. Based on a temperature profile representative of the basin, transient thermo-hydraulic simulations were performed along a representative vertical cross-section of about 400 km within the Lower Cretaceous multi-layer aquifer. Four paleoclimatic scenarios are the combination of two paleotemperature climatic forcings and two hydrodynamic regimes, one of them taking into account the interruption of the recharge linked to permafrost development. The simulation results clearly show the transient nature of the basin’s thermal regime. Then, for the reference well, the majority of the thermal flux anomaly can be explained by advective and paleoclimatic mechanisms with a decrease in geothermal flux simulated up to a little over 30 mW/m², depending on the scenarios. Decrease in heat flux because of basin-scale subsurface flows in the Lower Cretaceous is around 15 mW/m². There are several ways forward from this first simple model, including simulation of development of permafrost and also the integration of vertical flows in the basin by use of a three-dimensional model to better explain the data.  相似文献