Role of sea surface temperature,Arctic sea ice and Siberian snow in forcing the atmospheric circulation in winter of 2012–2013     

Peings  Yannick  Magnusdottir  Gudrun 《Climate Dynamics》2015,45(5-6):1181-1206

Climate Dynamics - During the 2012–2013 winter, the negative phase of the North Atlantic Oscillation (NAO) predominated, resulting in a cold winter over Europe and northern Asia punctuated by...  相似文献   

The remarkable population size of the endangered clam Tridacna maxima assessed in Fangatau Atoll (Eastern Tuamotu, French Polynesia) using in situ and remote sensing data     

Andrefouet  Serge; Gilbert  Antoine; Yan  Laurent; Remoissenet  Georges; Payri  Claude; Chancerelle  Yannick 《ICES Journal of Marine Science》2005,62(6):1037-1048

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Monomethylmercury sources in a tropical artificial reservoir     

Bogdan Muresan  Daniel Cossa  Sandrine Richard  Yannick Dominique 《Applied Geochemistry》2008

The distribution and speciation of mercury (Hg) in the water column, the inputs (wet deposition and tributaries) and the outputs (atmospheric evasion and outlet) of an artificial partially anoxic tropical lake (Petit-Saut reservoir, French Guiana) were investigated on a seasonal basis in order to appraise the cycling and transformations of this metal. The total mercury (HgT) concentrations in the oxygenated epilimnetic waters averaged 5 ± 3 pmol L⁻¹ in the unfiltered samples (HgT_UNF) and 4 ± 2 pmol L⁻¹ in the dissolved (HgT_D) phase (<0.45 μm). On average, the monomethylmercury (MMHg) constituted 8%, 40% and 18% of the HgT in the dissolved phase, the particulate suspended matter and in the unfiltered samples, respectively. Covariant elevated concentrations of particulate MMHg and chlorophyll a in the epilimnion suggest that phytoplankton is an active component for the MMHg transfer in the lake. In the anoxic hypolimnion the HgT_UNF averages 13 ± 6 pmol L⁻¹ and the HgT_D 8 ± 4 pmol L⁻¹. The averages of MMHg_P and MMHg_D in hypolimnetic waters were two and three times the corresponding values of the epilimnion, 170 ± 90 pmol g⁻¹ and 0.9 ± 0.5 pmol L⁻¹, respectively. In the long dry and wet seasons, at the flooded forest and upstream dam sampling stations, the vertical profiles of MMHg_D concentrations accounted for two distinct maxima: one just below the oxycline and the other near the benthic interface. Direct wet atmospheric deposition accounted for 14 moles yr⁻¹ HgT_UNF, with 0.7 moles yr⁻¹ as MMHg_UNF, while circa 76 moles yr⁻¹ of HgT_UNF, with 4.7 moles yr⁻¹ as MMHg_UNF, coming from tributaries. Circa 78 moles (∼17% as MMHg) are annually exported through the dam, while 23 moles yr⁻¹ of Hg⁰ evolve in the atmosphere. A mass balance calculation suggests that the endogenic production of MMHg_UNF attained 8.1 moles yr⁻¹, corresponding to a methylation rate of 0.06% d⁻¹. As a result, the Petit-Saut reservoir is a large man-made reactor that has extensively altered mercury speciation in favor of methylated species.  相似文献   

Toward the snowball earth deglaciation…     

Guillaume Le Hir  Yannick Donnadieu  Gerhard Krinner  Gilles Ramstein 《Climate Dynamics》2010,35(2-3):285-297

The current state of knowledge suggests that the Neoproterozoic snowball Earth is far from deglaciation even at 0.2 bars of CO₂. Since understanding the termination of the fully ice-covered state is essential to sustain, or not, the snowball Earth theory, we used an Atmospheric General Climate Model (AGCM) to explore some key factors which could induce deglaciation. After testing the models’ sensitivity to their parameterizations of clouds, CO₂ and snow, we investigated the warming effect caused by a dusty surface, associated with ash release during a mega-volcanic eruption. We found that the snow aging process, its dirtiness and the ash deposition on the snow-free ice are key factors for deglaciation. Our modelling study suggests that, under a CO₂ enriched atmosphere, a dusty snowball Earth could reach the deglaciation threshold.  相似文献   

High-resolution analysis of submarine lobes deposits: Seismic-scale outcrops of the Lauzanier area (SE Alps, France)     

Thierry Mulder  Yannick Callec  Philippe Joseph  Cécile Robin  Tristan Salles  Jonathan Allard  Emmanuelle Ducassou  Brice Ferger  Vincent Hanquiez  Elodie Marchès  Sébastien Zaragosi 《Sedimentary Geology》2010,229(3):160-191

The Lauzanier area represents the northernmost extension of the Annot Sandstone series and contains deposits between 650 and 900 m-thick. This basin was active from upper Bartonian or lower Priabonian to early Rupelian. It is composed of two superposed units separated by a major unconformity. The sediment supply is due to channelled flows coming from the south. Flow processes include mass flow to turbidity currents. The size of the particles and the absence of fine-grained sediment suggest a transport over a short distance. The Lower Unit is made of coarse-grained tabular beds interpreted as non-channelled lobe deposits. The Upper Unit is made of massive conglomerates interpreted as the channelled part of lobes. These lobe deposits settle in a tectonically confined basin according to topographic compensation that occurs from bed scale to unit scale. The abrupt progradation between the lower and the upper unit seems related to a major tectonic uplift in the area. This uplift is also suggested by a change in the petrographic nature of the source and an abrupt coarsening of the transported clasts.This field example allows providing high resolution analysis for depositional sedimentary sequences of terminal lobe deposits in a coarse-grained turbidite system. The outcrop analysis shows the lateral evolution of deposits and the system progradation allows a longitudinal analysis of facies evolution by superposing on the same outcrops the channelled lobe system and the non-channelled lobe system. These results of high-resolution outcrop analysis can be extrapolated to results obtained on sedimentary lobes in recent deep-sea turbidite system that are either restricted to cores, or with a lesser resolution (seismic).  相似文献   

Application of expert rules in indirect approaches for landslide susceptibility assessment   总被引：3，自引：2，他引：1  

Yannick Thiery  Olivier Maquaire  Mathieu Fressard 《Landslides》2014,11(3):411-424

Landslide susceptibility (LS) assessment by indirect approaches presents some limitations due to (1) the tendency to simplify the environmental factors (i.e., variables) and (2) the assumptions that landslides occur under the same combination of variables for a study site. Recently, some authors have discussed the interest to introduce expert knowledge in the indirect approaches in order to improve the quality of indirect LS maps. However, if the results are reliable, the procedures used seem fastidious and a very good knowledge of the study site is essential. The objectives of this paper are to discuss a methodology to introduce the expert knowledge in the indirect mapping process. After the definition of the expert rules associated to three landslide types, several indirect LS maps are produced by two indirect exploratory approaches, based on fuzzy set theory and on a modification of a bivariate method called expert weight of evidence. Then, the indirect LS maps are confronted to a landslide inventory and a LS map produced by a direct approach. The analyses indicate that the methodology used to introduce the expert rules in the mapping process increases the predictive power of indirect LS map. Finally, some indications about advantages and drawbacks of each approach are given to help the geoscientist to introduce his expert knowledge in the landslide susceptibility mapping process.  相似文献   

European temperatures in CMIP5: origins of present-day biases and future uncertainties     

Julien Cattiaux  Hervé Douville  Yannick Peings 《Climate Dynamics》2013,41(11-12):2889-2907

European temperatures and their projected changes under the 8.5 W/m² Representative Concentration Pathway scenario are evaluated in an ensemble of 33 global climate models participating in the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Respective contributions of large-scale dynamics and local processes to both biases and changes in temperatures, and to the inter-model spread, are then investigated from a recently proposed methodology based on weather regimes. On average, CMIP5 models exhibit a cold bias in winter, especially in Northern Europe. They overestimate summer temperatures in Central Europe, in association with a greater diurnal range than observed. The projected temperature increase is stronger in summer than in winter, with the highest summer warming occurring over Mediterranean regions. Links between biases and sensitivities are evidenced in winter, suggesting a potential influence of snow cover biases on the projected surface warming. A brief analysis of daily temperature extremes suggests that the intra-seasonal variability is projected to decrease (slightly increase) in winter (summer). Then, in order to understand model discrepancies in both present-day and future climates, we disentangle effects of large-scale atmospheric dynamics and regional physical processes. In particular, in winter, CMIP5 models simulate a stronger North-Atlantic jet stream than observed and, in contrast with CMIP3 results, the majority of them suggests an increased frequency of the negative phase of the North-Atlantic Oscillation under future warming. While large-scale circulation only has a minor contribution to ensemble-mean biases or changes, which are primarily dominated by non-dynamical processes, it substantially affects the inter-model spread. Finally, other sources of uncertainties, including the North-Atlantic warming and local radiative feedbacks related to snow cover and clouds, are briefly discussed.  相似文献   

Formation and evolution of S0 galaxies: a SAURON case study of NGC 7332     

Jesús Falcón-Barroso  Reynier F. Peletier  Eric Emsellem    Harald Kuntschner  Kambiz Fathi  Martin Bureau  Roland Bacon  Michele Cappellari  Yannick Copin  Roger L. Davies  Tim de Zeeuw 《Monthly notices of the Royal Astronomical Society》2004,350(1):35-46

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The three-dimensional power spectrum of dark and luminous matter from the VIRMOS-DESCART cosmic shear survey     

Ue-Li Pen  Tingting Lu  Ludovic van Waerbeke  Yannick Mellier 《Monthly notices of the Royal Astronomical Society》2003,346(3):994-1008

We present the first optimal power spectrum estimation and three-dimensional deprojections for the dark and luminous matter and their cross-correlations. The results are obtained using a new optimal fast estimator, deprojected using minimum variance and Singular Value Decomposition (SVD) techniques. We show the resulting 3D power spectra for dark matter and galaxies, and their covariance for the VIRMOS-DESCART weak lensing shear and galaxy data. The survey is most sensitive to non-linear scales   k _NL∼ 1 h Mpc⁻¹  . On these scales, our 3D power spectrum of dark matter is in good agreement with the RCS 3D power spectrum found by Tegmark & Zaldarriaga. Our galaxy power is similar to that found by the 2MASS survey, and larger than that of SDSS, APM and RCS, consistent with the expected difference in galaxy population.
We find an average bias   b = 1.24 ± 0.18  for the I -selected galaxies, and a cross-correlation coefficient   r = 0.75 ± 0.23  . Together with the power spectra, these results optimally encode the entire two point information about dark matter and galaxies, including galaxy–galaxy lensing. We address some of the implications regarding galaxy haloes and mass-to-light ratios. The best-fitting 'halo' parameter   h ≡ r / b = 0.57 ± 0.16  , suggesting that dynamical masses estimated using galaxies systematically underestimate total mass.
Ongoing surveys, such as the Canada–France–Hawaii Telescope Legacy Survey, will significantly improve on the dynamic range, and future photometric redshift catalogues will allow tomography along the same principles.  相似文献   

MétéEAU Nappes: a real-time water-resource-management tool and its application to a sandy aquifer in a high-demand irrigation context     

Surdyk  Nicolas  Thiéry  Dominique  Nicolas  Jérome  Gutierrez  Alexis  Vigier  Yannick  Mougin  Bruno 《Hydrogeology Journal》2022,30(6):1737-1749

The MétéEAU Nappes water-resource-management tool is presented. It is usable on the aquifer or part-of-aquifer scale for real-time observation of the state of the groundwater resource, and it is already operating in France. This online decision support tool is also able to predict the state of the resource in the short- and mid-terms. The paper explains the use of the tool in a case study in the Authion Valley, in the north-west of France, chosen for its context of tension surrounding the groundwater resource resulting from high volumes of abstraction for irrigation. The results of the simulation highlight the advantages of MétéEAU Nappes as a tool for prediction and simulation of the state of the groundwater resource. The results also show the advantages of this type of tool for water resource management, such as supplying local actors with reliable and real-time observations of the aquifer and providing forecasts to anticipate possible water shortage.

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