Evidence for solar forcing in variability of temperatures and pressures in Europe     

Jean-Louis Le Mouël  Elena Blanter  Mikhail Shnirman  Vincent Courtillot 《Journal of Atmospheric and Solar》2009,71(12):1309-1321

Daily temperature and pressure series from 55 European meteorological stations covering the 20th century are analyzed. The overall temperature mean displays a sharp minimum near 1940 and a step-like jump near 1987. We evaluate the evolution of disturbances of these series using mean squared inter-annual variations and “lifetimes”. The decadal to secular evolutions of solar activity and temperature disturbances display similar signatures over the 20th century. Because of heterogeneity of the climate system response to solar forcing, regional and seasonal approaches are key to successful identification of these signatures. Most of the solar response is governed by the winter months, as best seen near the Atlantic Ocean. Intensities of disturbances vary by factors in excess of 2, underlining a role for the Sun as a significant forcing factor of European atmospheric variations. We speculate about the possible origin of these solar signatures. The last figure of the paper exemplifies its main results.  相似文献   

Reply to Jackson and Cross' Comment on “Exceptionally Long MTBE Plumes of the Past Have Greatly Diminished”          下载免费PDF全文

James M. McDade  John A. Connor  Shawn M. Paquette  Julia M. Small 《Ground water》2016,54(2):153-154

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Inner thermal resonance in thermoelastic geological structures     

Jean-Louis Auriault 《Acta Geophysica》2014,62(5):993-1004

When investigating heterogeneous media such as composite materials or geological structures, it is convenient to replace them by macroscopic equivalent media, which simplifies computations a lot. In the paper, we look for the equivalent macroscopic model for describing seismic wave propagation and transient heat transfers in thermoelastic periodic geological structures made of rock or soil. We follow the route described in Auriault (2012), to investigating thermoelastic composite media. We use the method of multi-scale asymptotic expansions. By estimating the dimensionless numbers in the momentum and energy balances, we show that an equivalent macroscopic model exists for describing seismic waves at very low frequencies only. The model then shows a damping which is due to thermal resonance at the heterogeneity scale. At higher frequencies, such an equivalent macroscopic model does not exist. Macroscopic models for describing transient heat transfers do not exist.  相似文献   

Geochemistry,mineralogy, and zircon U–Pb–Hf isotopes in peraluminous A-type granite xenoliths in Pliocene–Pleistocene basalts of northern Pannonian Basin (Slovakia)     

Monika?Huraiová  Jean-Louis?Paquette  Patrik?Kone?ny  Abdel-Mouhcine?Gannoun  Vratislav?HuraiEmail authorView author&#;s OrcID profile 《Contributions to Mineralogy and Petrology》2017,172(8):59

Anorogenic granite xenoliths occur in alkali basalts coeval with the Pliocene–Pleistocene continental rifting of the Pannonian Basin. Observed granite varieties include peraluminous, calcic to peralkalic, magnesian to ferroan types. Quartz and feldspars are dominant rock-forming minerals, accompanied by minor early ilmenite and late magnetite–ulvöspinel. Zircon and Nb–U–REE minerals (oxycalciopyrochlore, fergusonite, columbite) are locally abundant accessory phases in calc-alkalic types. Absence of OH-bearing Fe, Mg-silicates and presence of single homogeneous feldspars (plagioclase in calcic types, anorthoclase in calc-alkalic types, ferrian Na-sanidine to anorthoclase in alkalic types) indicate water-deficient, hypersolvus crystallization conditions. Variable volumes of interstitial glass, absence of exsolutions, and lacking deuteric hydrothermal alteration and/or metamorphic/metasomatic overprint are diagnostic of rapid quenching from hypersolidus temperatures. U–Pb zircon ages determined in calcic and calc-alkalic granite xenoliths correspond to a time interval between 5.7 and 5.2 Ma. Positive εHf values (14.2 ± 3.9) in zircons from a 5.2-Ma-old calc-alkalic granite xenolith indicate mantle-derived magmas largely unaffected by the assimilation of crustal material. This is in accordance with abundances of diagnostic trace elements (Rb, Y, Nb, Ta), indicating A₁-type, OIB-like source magmas. Increased accumulations of Nb–U–REE minerals in these granites indicate higher degree of the magmatic differentiation reflected in Rb-enrichment, contrasting with Ba-enrichment in barren xenoliths. Incipient charnockitization, i.e. orthopyroxene and ilmenite crystallization from interstitial silicate melt, was observed in many granite xenoliths. Thermodynamic modeling using pseudosections showed that the orthopyroxene growth may have been triggered by water exsolution from the melt during ascent of xenoliths in basaltic magma. Euhedral-to-skeletal orthopyroxene growth probably reflects contrasting ascent rates of basaltic magma with xenoliths, intermitted by the stagnation in various crustal levels at a <3 kbar pressure. The Tertiary suite of intra-plate, mantle-derived A₁-type granites and syenites is geochemically distinct from pre-Tertiary, post-orogenic A₂-type granites of the Carpatho–Pannonian region, which exhibit geochemical features diagnostic of crustal melting along continental margins.  相似文献   

Spatial and Temporal Dependence of Temperature Variations Induced by Atmospheric Pressure Variations in Shallow Underground Cavities     

Frederic Perrier  Jean-Louis Le Mouël  Patrick Richon 《Pure and Applied Geophysics》2010,167(3):253-276

Pressure-induced temperature (PIT) variations are systematically observed in the atmosphere of underground cavities. Such PIT variations are due to the compressibility of the air, damped by heat exchange with the rock surface. It is important to characterize such processes for numerous applications, such as the preservation of painted caves or the assessment of the long-term stability of underground laboratories and underground waste repositories. In this paper we thoroughly study the spatiotemporal dependence of the PIT response versus frequency using vertical and horizontal profiles of temperature installed in an abandoned underground quarry located in Vincennes, near Paris. The PIT response varies from about 20 × 10^?3°C hPa^?1 at a frequency of 2 × 10^?4 Hz to 2–3 × 10^?3°C hPa^?1 at a frequency of one cycle per day. An analytical expression based on a simple heat exchange model accounts for the observed features of the PIT response and allows for correcting the measured time series, having standard deviations of about 10^?2°C, to residual variations with a standard deviation of about 2 × 10^?3°C. However, a frequency-dependent attenuation of the response, corresponding to a reduction in amplitude with a factor varying from 2 to 3, is observed near the walls. This effect is not included in the simple analytical expression, but it can be accounted for by a one-dimensional differential equation, solved numerically, where temperature variations in the atmosphere are damped by an effective radiative coupling with the rock surface, complemented by a diffusive coupling near the walls. The TIP response is observed to remain stable over several years, but a large transient enhancement of about a factor of two is observed near the roof at one location from July to October 2005. In a cavity located below the Paris Observatory, an additional contribution is identified in the PIT response function versus frequency for frequencies smaller than 2 × 10^?5 Hz. This contribution can be described using a modified analytical expression that includes the effect of heat diffusion into the surrounding rock. Using this expression, in this case also, the temperature time series can then be corrected, giving a residual standard deviation smaller than 1.6 × 10^?3°C. Transient temporal variations of the PIT response are observed in all sites, with possible nonlinear components in the PIT. Such effects are not properly understood at this stage, and limit the reduction of time series to standard deviations of the order of 2 × 10^?3°C, and consequently limit the search for new transient or seasonal temperature signals, for example due to the presence of tiny heat sources in the cavity or to geodynamical effects.  相似文献   

Sedimentological and geochemical records of past trophic state and hypolimnetic anoxia in large,hard-water Lake Bourget,French Alps     

Charline Giguet-Covex  Fabien Arnaud  Jérôme Poulenard  Dirk Enters  Jean-Louis Reyss  Laurent Millet  Jérome Lazzaroto  Olivier Vidal 《Journal of Paleolimnology》2010,43(1):171-190

Sedimentological, geochemical and particle-size analyses were used to reconstruct the evolution of both trophic state and hypolimnetic anoxia in Lake Bourget (French Alps) during the last century. Radionuclide dating (²¹⁰Pb, ¹³⁷Cs and ²⁴¹Am) confirmed the annual rhythm of laminations in the upper sediment profile. In Lake Bourget, biochemical varves are triplets composed of a diatom layer (spring lamina), a bio-precipitated calcite-rich layer (spring/summer lamina), and a layer rich in organic matter and detrital particles (winter lamina). The onset of eutrophication and the first appearance of an anoxic facies occurred simultaneously and were dated by laminae counting to AD 1943±1 year. Persistent anoxic conditions began in AD 1960. Eutrophication is characterised by drastic increases in the flux of biogenic silica (mostly diatoms), lacustrine organic matter, and larger calcite crystals (15–30 μm). The increase of organic matter also represents a marker of the onset of anoxic conditions in the hypolimnion. Our results show that eutrophication was the main factor controlling anoxia in the hypolimnion. This eutrophication was caused mostly by the inflow of untreated sewage effluents, and to a lesser extent, by input of fertilizer-derived phosphorus during floods of the Rhone River and run-off from the lake catchment. The Rhone River, however, can also be a source of re-oxygenation via underflows that originate during flood events. Oxygenation of the hypolimnion is also controlled by low winter temperatures, which enable turnover of the lake. Thus, global warming, associated with a forecasted reduction in precipitation, might reduce the efficiency of hypolimnetic re-oxygenation in Lake Bourget.  相似文献   

Centrifuge modelling of raked piles   总被引：1，自引：1，他引：0  

Sandra Escoffier  Jean-Louis Chazelas  Jacques Garnier 《Bulletin of Earthquake Engineering》2008,6(4):689-704

Inclined piles are prohibited by many codes in seismic areas. Nevertheless the battered effect has not yet been clarified because very few data are available. The present work is a comparison, at reduced scale in the centrifuge, of the response of two simplified pile groups: a 1 × 2 vertical piles and 1 × 2 pile group with one inclined pile. Two configurations are considered: end-bearing and floating pile group, both with pile heads rigidly fixed with a massive cap. First, repeatability tests under horizontal cyclic loading were performed on both floating pile groups. Secondly, repeated horizontal impact tests were performed on both end-bearing pile groups. These impact tests, which highlight the influence of inclined piles on the inertial response of a group, are a first step for the more complex analysis of the performance of such groups under seismic loads where inertial and kinematic interactions are combined. The first part of this work revealed the influence of sand structure around the inclined pile tip on the repeatability of the tests performed on floating pile groups. The second part highlighted differences in the dynamic response between the two end-bearing pile groups through measurements of the pile cap acceleration, the bending moment profile and the axial load in the piles.  相似文献   

Determination of Forty Four Major and Trace Elements in GPMA Magmatic Rock Reference Materials using X-ray Fluorescence Spectrometry (XRF) and Instrumental Neutron Activation Analysis (INAA)   总被引：1，自引：0，他引：1  

Mohammed El Maghraoui  Jean-Louis Joron  Joël Etoubleau  Pierre Cambon  Michel Treuil 《Geostandards and Geoanalytical Research》1999,23(1):59-68

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A Tiered Approach to Evaluating Salinity Sources in Water at Oil and Gas Production Sites          下载免费PDF全文

Shawn M. Paquette  Lisa J. Molofsky  John A. Connor  Kenneth L. Walker  Harley Hopkins  Ayan Chakraborty 《Ground water》2017,55(5):757-769

A suspected increase in the salinity of fresh water resources can trigger a site investigation to identify the source(s) of salinity and the extent of any impacts. These investigations can be complicated by the presence of naturally elevated total dissolved solids or chlorides concentrations, multiple potential sources of salinity, and incomplete data and information on both naturally occurring conditions and the characteristics of potential sources. As a result, data evaluation techniques that are effective at one site may not be effective at another. In order to match the complexity of the evaluation effort to the complexity of the specific site, this paper presents a strategic tiered approach that utilizes established techniques for evaluating and identifying the source(s) of salinity in an efficient step‐by‐step manner. The tiered approach includes: (1) a simple screening process to evaluate whether an impact has occurred and if the source is readily apparent; (2) basic geochemical characterization of the impacted water resource(s) and potential salinity sources coupled with simple visual and statistical data evaluation methods to determine the source(s); and (3) advanced laboratory analyses (e.g., isotopes) and data evaluation methods to identify the source(s) and the extent of salinity impacts where it was not otherwise conclusive. A case study from the U.S. Gulf Coast is presented to illustrate the application of this tiered approach.  相似文献   

Photométries comparées des émissions de l'hydrogène et de l'hélium dans les régions externes des protubérances     

Jean-Louis Leroy 《Solar physics》1969,7(2):221-237

Résumé La variation du rapport d'intensités H/D3 est étudiée dans les régions périphériques de deux protubérances d'éclat assez faibles et qui étaient suspendues au-dessus de la chromosphère. La partie supérieure des protubérances est relativement plus intense en D3, tandis qu'en dessous des protubérances le phénomène inverse s'observe. Il faut considérer que ces variations ne peuvent pas s'expliquer par des phénomènes de saturation, mais pourraient résulter du régime dynamique de la matière qui émet les radiations observées.  相似文献