Observing water-level variations from space-borne high-resolution Synthetic Aperture Radar (SAR) image correlation     

Daniel Raucoules  Gonéri Le Cozannet  Marcello de Michele  Sylvain Capo 《国际地球制图》2018,33(9):977-987

The potential of correlating high-resolution Synthetic Aperture Radar images to estimate local water-level variations is analysed based on observing the motions of floating structures. By computing range and azimuth offsets on a COSMO-SkyMed multi-temporal data-set in an area of the French Atlantic Coast, displacement signatures were detected in several harbours of the region. They can be associated with specific floating structures, whose vertical motion is mostly driven by tides. Although the image resolution is not the best achievable for the COSMO-SkyMed sensor, comparison with ground-based tide information revealed that the obtained space-borne measurements are consistent with the tide gauges to a decimetric accuracy. Even if the requirements for traditional users of tidal data are not met by the current revisit time of the COSMO-SkyMed constellation, the method proposed here provides complementary measures, which are already well aligned to requirements of users concerned with long-term sea-level variation and river or lake water stocks.  相似文献   

Variability of the water stock dynamics in karst: insights from surface-to-tunnel geophysics     

Fores  Benjamin  Champollion  C&#;dric  Lesparre  Nolwenn  Pasquet  Sylvain  Martin  Aur&#;lie  Nguyen  Fr&#;d&#;ric 《Hydrogeology Journal》2021,29(6):2077-2089

Hydrogeology Journal - A hydrogeophysical field experiment was conducted on a karst hydrosystem in the south of France to investigate groundwater transfer and storage variability at a scale of a...  相似文献   

On the advantage of sharing a holdfast: effects of density and occurrence of kin aggregation in the kelp Lessonia berteroana          下载免费PDF全文

Nicolás I. Segovia  Julio A. Vásquez  Sylvain Faugeron  Pilar A. Haye 《Marine Ecology》2015,36(4):1107-1117

We investigated the density‐dependent and genetic relatedness that regulate the occurrence of inter‐individual (genet) fusion forming plurigenotypic organisms in the brown alga Lessonia berteroana. Recruitment generally occurs at high densities in the inter‐tidal, allowing contact of neighbouring holdfasts as they grow and expand on the substrate. Algal density, by contrast, is regulated by the effects of herbivory and wave impact, which often lead to low holdfast density. Herein, we investigated whether the occurrence of plurigenotypic organisms and their genotypic composition (number of genotypes per plurigenotypic organism) are density dependent and affected by kin selection in the inter‐tidal kelp L. berteroana. Four microsatellite loci were used to analyse DNA from 260 samples obtained from shared and non‐shared holdfasts, at two sites with high and two site with low holdfast density. Analyses showed that fusions forming plurigenotypic organisms are extremely common. Interestingly, the frequency of fusions was higher in low‐density sites, in which 100% of the plants had at least two genotypes and the average was 3.5. In high‐density sites, 62% of plants were plurigenotypic, with an average of 2.8 genotypes per plant. Additionally, we found that genotypes that shared a holdfast had a significantly higher genetic relatedness than the average in the population, compatible with a kin structure. Density dependence and kin structure suggest that the occurrence of plurigenotypic organisms is linked to environmental quality, and that kin or multilevel selection may be favouring the fusion of genetically related genets.  相似文献   

A SEM-based method to determine the mineralogical composition and the particle size distribution of suspended sediment     

Sylvain Pinet  Bruno Lartiges  Jean-Michel Martinez  Sylvain Ouillon 《国际泥沙研究》2019,34(2):85-94

A robust method for characterizing the mineralogy of suspended sediment in continental rivers is introduced. It encompasses 3 steps: the filtration of a few milliliters of water, measurements of X-ray energy dispersive spectra using Scanning Electron Microscopy (SEM), and robust machine learning tools of classification. The method is applied to suspended particles collected from various Amazonian rivers. A total of more than 204,000 particles were analyzed by SEM-EDXS (Energy Dispersive X-ray Spectroscopy), i.e. about 15,700 particles per sampling station, which lead to the identification of 15 distinct groups of mineralogical phases. The size distribution of particles collected on the filters was derived from the SEM micrographs taken in the backscattered electron imaging mode and analyzed with ImageJ freeware. The determination of the main mineralogical groups composing the bulk sediment associated with physical parameters such as particle size distribution or aspect ratio allows a precise characterization of the load of the terrigenous particles in rivers or lakes. In the case of the Amazonian rivers investigated, the results show that the identified mineralogies are consistent with previous studies as well as between the different samples collected. The method enabled the evolution of grain size distribution from fine to coarse material to be described in the water column. Implications about hydrodynamic sorting of mineral particles in the water column are also briefly discussed. The proposed method appears well suited for intensive routine monitoring of suspended sediment in river systems.  相似文献   

Effect of Biochar and Amendments on Pb and As Phytotoxicity and Phytoavailability in a Technosol     

Romain Nandillon  Florie Miard  Manhattan Lebrun  Marie Gaillard  Stphane Sabatier  Sylvain Bourgerie  Fabienne Battaglia‐Brunet  Domenico Morabito 《洁净——土壤、空气、水》2019,47(3)

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Bosumtwi impact structure,Ghana: Evidence for fluidized emplacement of the ejecta     

David Baratoux  Cheikh Ahmadou Bamba Niang  Wolf Uwe Reimold  Marian Selorm Sapah  Mark Walter Jessell  Daniel Boamah  Gayane Faye  Sylvain Bouley  Olivier Vanderhaeghe 《Meteoritics & planetary science》2019,54(10):2541-2556

The about 10.5 km diameter Bosumtwi impact crater is one of the youngest large impact structures on Earth. The crater rim is readily noticed on topographic maps or in satellite imagery. It defines a circular basin filled by water (Lake Bosumtwi) and lacustrine sediments. The morphology of this impact structure is also characterized by a circular plateau extending beyond the rim and up to 9–10 km from the center of the crater (about 2 crater radii). This feature comprises a shallow ring depression, also described as an annular moat, and a subdued circular ridge at its outer edge. The origin of this outermost feature could so far not be elucidated based on remote sensing data only. Our approach combines detailed topographic analysis, including roughness mapping, with airborne radiometric surveys (mapping near‐surface K, Th, U concentrations) and field observations. This provides evidence that the moat and outer ring are features inherited from the impact event and represent the partially eroded ejecta layer of the Bosumtwi impact structure. The characteristics of the outer ridge indicate that ejecta emplacement was not purely ballistic but requires ejecta fluidization and surface flow. The setting of Bosumtwi ejecta can therefore be considered as a terrestrial analog for rampart craters, which are common on Mars and Venus, and also found on icy bodies of the outer solar system (e.g., Ganymede, Europa, Dione, Tethys, and Charon). Future studies at Bosumtwi may therefore help to elucidate the mechanism of formation of rampart craters.  相似文献   

Determination of the gravimetric factor at the Chandler period from Earth orientation data and superconducting gravimetry observations   总被引：1，自引：0，他引：1  

Sylvain Loyer  Jacques Hinderer  & Jean-Paul Boy 《Geophysical Journal International》1999,136(1):1-7

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An elastic–viscous–plastic sea ice model formulated on Arakawa B and C grids     

Sylvain Bouillon  Miguel ngel Morales Maqueda  Vincent Legat  Thierry Fichefet 《Ocean Modelling》2009,27(3-4):174-184

The elastic–viscous–plastic (EVP) sea ice rheology has been introduced in the large-scale Louvain-la-Neuve sea-Ice Model, version 2 (LIM2), and its performance has been evaluated. Centred difference versions of the rheology have been implemented on both an Arakawa B grid and a C grid, and their performance have been intercompared in coupled simulations with the Nucleus for European Modelling of the Ocean (NEMO) model. Integrations with both implementations lead to fairly similar results which compare well with observations and with previous LIM simulations. The C grid version, however, offers a number of advantages: (a) easier ice coupling with NEMO, which is itself defined on a C grid; (b) possibility of representing ice transport across one-cell-wide straits and passages; (c) better representation of inertial-plastic compressive waves. For these reasons, we recommend the use of the C grid EVP formulation of the ice dynamics in future LIM applications.  相似文献   

Raman spectroscopic properties and Raman identification of CaS‐MgS‐MnS‐FeS‐Cr2FeS4 sulfides in meteorites and reduced sulfur‐rich systems     

Caroline Avril  Valérie Malavergne  Razvan Caracas  Brigitte Zanda  Bruno Reynard  Emeline Charon  Ema Bobocioiu  Fabrice Brunet  Stephan Borensztajn  Sylvain Pont  Martine Tarrida  François Guyot 《Meteoritics & planetary science》2013,48(8):1415-1426

Raman spectra were acquired on a series of natural and synthetic sulfide minerals, commonly found in enstatite meteorites: oldhamite (CaS), niningerite or keilite ((Mg,Fe)S), alabandite (MnS), troilite (FeS), and daubreelite (Cr₂FeS₄). Natural samples come from three enstatite chondrites, three aubrites, and one anomalous ungrouped enstatite meteorite. Synthetic samples range from pure endmembers (CaS, FeS, MgS) to complex solid solutions (Fe, Mg, Ca)S. The main Raman peaks are localized at 225, 285, 360, and 470 cm^?1 for the Mg‐rich sulfides; at 185, 205, and 285 cm^?1 for the Ca‐rich sulfides; at 250, 370, and 580 cm^?1 for the Mn‐rich sulfides; at 255, 290, and 365 cm^?1 for the Cr‐rich sulfides; and at 290 and 335 cm^?1 for troilite with, occasionally, an extra peak at 240 cm^?1. A peak at 160 cm^?1 is present in all Raman spectra and cannot be used to discriminate between the different sulfide compositions. According to group theory, none of the cubic monosulfides oldhamite, niningerite, or alabandite should present first‐order Raman spectra because of their ideal rocksalt structure. The occurrence of broad Raman peaks is tentatively explained by local breaking of symmetry rules. Measurements compare well with the infrared frequencies calculated from first‐principles calculations. Raman spectra arise from activation of certain vibrational modes due to clustering in the solid solutions or to coupling with electronic transitions in semiconductor sulfides.  相似文献   

Hydroclimate variability and long-lead forecasting of rainfall over Thailand by large-scale atmospheric variables     

Nkrintra Singhrattna  Sylvain R. Perret 《水文科学杂志》2013,58(1):26-41

Abstract

The development of statistical relationships between local hydroclimates and large-scale atmospheric variables enhances the understanding of hydroclimate variability. The rainfall in the study basin (the Upper Chao Phraya River Basin, Thailand) is influenced by the Indian Ocean and tropical Pacific Ocean atmospheric circulation. Using correlation analysis and cross-validated multiple regression, the large-scale atmospheric variables, such as temperature, pressure and wind, over given regions are identified. The forecasting models using atmospheric predictors show the capability of long-lead forecasting. The modified k-nearest neighbour (k-nn) model, which is developed using the identified predictors to forecast rainfall, and evaluated by likelihood function, shows a long-lead forecast of monsoon rainfall at 7–9 months. The decreasing performance in forecasting dry-season rainfall is found for both short and long lead times. The developed model also presents better performance in forecasting pre-monsoon season rainfall in dry years compared to wet years, and vice versa for monsoon season rainfall.

Editor Z.W. Kundzewicz

Citation Singhrattna, N., Babel, M.S. and Perret, S.R., 2012. Hydroclimate variability and long-lead forecasting of rainfall over Thailand by large-scale atmospheric variables. Hydrological Sciences Journal, 57 (1), 26–41.  相似文献