The 2010 European Venus Explorer (EVE) mission proposal     

Colin Frank Wilson  Eric Chassefière  Emmanuel Hinglais  Kevin H. Baines  Tibor S. Balint  Jean-Jacques Berthelier  Jacques Blamont  Georges Durry  Csaba S. Ferencz  Robert E. Grimm  Takeshi Imamura  Jean-Luc Josset  Fran?ois Leblanc  Sebastien Lebonnois  Johannes J. Leitner  Sanjay S. Limaye  Bernard Marty  Ernesto Palomba  Sergei V. Pogrebenko  Scot C. R. Rafkin  Dean L. Talboys  Rainer Wieler  Liudmila V. Zasova  Cyrill Szopa 《Experimental Astronomy》2012,33(2-3):305-335

The European Venus Explorer (EVE) mission described in this paper was proposed in December 2010 to ESA as an ‘M-class’ mission under the Cosmic Vision programme. It consists of a single balloon platform floating in the middle of the main convective cloud layer of Venus at an altitude of 55?km, where temperatures and pressures are benign (～25°C and ～0.5 bar). The balloon float lifetime would be at least 10 Earth days, long enough to guarantee at least one full circumnavigation of the planet. This offers an ideal platform for the two main science goals of the mission: study of the current climate through detailed characterization of cloud-level atmosphere, and investigation of the formation and evolution of Venus, through careful measurement of noble gas isotopic abundances. These investigations would provide key data for comparative planetology of terrestrial planets in our solar system and beyond.  相似文献   

Incorporating fuzzy set methodologies in a DBMS repository for the application domain of GIS     

Emmanuel Stefanakis  Michael Vazirgiannis  Timos Sellis 《International journal of geographical information science》2013,27(7):657-675

It has been recently recognized that fuzzy set theory provides useful concepts and tools for both the representation and analysis of the uncertainty related to geographical data. Hence the incorporation of fuzzy set methodologies into a DBMS repository for the application domain of GIS should be beneficial and will improve its level of intelligence. Focusing in this area the paper addresses both a representation and a reasoning issue. Specifically, it extends a general spatial data model to deal with the uncertainty of geographical entities, and shows how the standard data interpretation operations available in GIS packages may be extended to support the fuzzy spatial reasoning. Representative geographical operations, suchas the fuzzy overlay, fuzzy distance and fuzzy select, are examined, while several real world examples are given.  相似文献   

NRR, Moving on: Editorial     

Emmanuel John M. Carranza 《Natural Resources Research》2013,22(1):1-4

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U–Pb Zircon Age Constraining the Source and Provenance of Gem‐Bearing Late Cenozoic Detrital Deposits,Mamfe Basin,SW Cameroon     

Nguo Sylvestre KANOUO  Khin ZAW  Rose Fouateu YONGUE  Frederick Lin SUTHERLAND  Sebastien MEFFRE  Emmanuel NJONFANG  Changqian MA  Milan Stafford TCHOUATCHA 《Resource Geology》2012,62(3):316-324

Zircons and other heavy minerals (corundum, rutile, ilmenite, magnetite, sillimanite) are identified in the Nsanaragati gem corundum placer deposit, in the western part of the Mamfe sedimentary basin, SW Cameroon. These alluvial minerals have different morphological characteristics and zircons, in particular, vary mostly in colour and shape. They are reddish, brownish, yellowish, pink or colourless. These minerals form rounded and sub‐rounded alluvial grains, prismatic, pyramidal or dipyramidal crystals. Reddish zircons retain their original crystallographic shape. Trace element and U–Pb isotopic geochemical analyses of these reddish zircons, using the LA‐ICP‐MS method give significant Hf (4576–6334 ppm), Th (46–1565 ppm) and U (66–687 ppm) contents, with Th/U ratio ranging from 0.6 to 3.0. The ²⁰⁶Pb/²³⁸U corrected mean age gave 12.39 ± 0.55 Ma, which characterizes an Upper Cenozoic (Serravallian) magmatic event. The zircons are probably sourced from a magmatic field in the South eastern boundary of the Cross River Formation. The Cameroon Volcanic Line of basaltic and alkaline lavas and intrusions which lie east of the Mamfe Basin mostly range in age from 37 Ma to <1 Ma. The zircons may also relate to the Mount Bambouto plateau lavas which lie northeast of the Mamfe sedimentary basin and have an eruptive age range of 21–14 Ma. The oldest Nsanaragati reddish zircon ages overlap within error with the end stages of the Bambouto eruptions. This eruptive or a related episode provides a potential source for megacrystic reddish zircons within the Nsanagarati placer deposit.  相似文献   

Silver and lead in high-altitude lake sediments: Proxies for climate changes and human activities     

Marion Garçon  Catherine Chauvel  Emmanuel Chapron  Xavier Faïn  Mingfang Lin  Sylvain Campillo  Sarah Bureau  Marc Desmet  Marie-Christine Bailly-Maître  Laurent Charlet 《Applied Geochemistry》2012

High-altitude lake sediments are often used as archives for environmental changes and their chemical and isotopic compositions provide significant constraints on natural and anthropogenic long-term changes that have occurred in their catchment area. Here, trace-element concentrations and Pb isotopes are presented for two sedimentary cores from Lake Blanc Huez in the French Alps, to trace the impact of climate changes and human activities over the Holocene. Lead and Ag contents are very high and clearly dominated by input from a Pb–Ag vein located a few meters from the lakeshore, a vein that also buffers the Pb isotopes. Mining of this vein in medieval times is recorded in the corresponding lake sediments with high Ag content coupled with high Pb/U ratio. These chemical characteristics can be used to constrain the major Holocene climate changes. Significant advances of glaciers next to the lake produced sediments with Ag and Pb concentration peaks and high Pb/U ratios due to accelerated erosion of the Pb–Ag vein, similar to the effects of the medieval mining. In contrast, reduced glacier activity led to the formation of organic-rich sediments with high U and As contents and low Pb/U ratios. More generally, the observed combination of chemical changes could be used elsewhere to decipher environmental changes over long periods of time.  相似文献   

Les vertébrés continentaux de l’Adrar Mgorn (Maroc,Paléocène); une dispersion de mammifères transtéthysienne aux environs de la limite mésozoïque/ cénozoïque ?     

Emmanuel Gheerbrant 《Geodinamica Acta》2013,26(4-5):233-246

Résumé

— Le gisement paléocène sud-marocain de l’Adrar Mgorn recèle les plus anciens Mammifères placentaires africains, dont la plupart sont les premiers reconnus dans le domaine sud-téthysien. L’identification, parmi eux, d’« Insectivores » paléoryctidés, très proches des genres strictement nord-américains Cimolestes et Palaeoryctes (Crétacé supérieur et/ou Paléocène), suggère une liaison par voie continentale des domaines nord-américain et africain autour de la limite Crétacé supérieur/Tertiaire. Celle-ci suppose une traversée transtéthysienne dont nous discutons les possibilités à la lumière des données paléogéographiques.  相似文献   

Assimilating altimetric data to control the tropical instability waves: an observing system simulation experiment study     

Clement Ubelmann  Jacques Verron  Jean-Michel Brankart  Pierre Brasseur  Emmanuel Cosme 《Ocean Dynamics》2012,62(6):867-880

Tropical instability waves (TIWs) are not easily simulated by ocean circulation models primarily because such waves are very sensitive to wind forcing. In this study, we investigate the impact of assimilating sea surface height (SSH) observations on the control of TIWs in an observing system simulation experiment (OSSE) context based on a regional model configuration of the tropical Atlantic. A Kalman filtering method with suitable adaptations is found to be successful when altimetric data are assimilated in conjunction with sea surface temperature and some in situ temperature/salinity profiles. In this rather realistic system, the TIW phase is roughly controlled with a single nadir observing satellite. However, a right correction of the TIW structure and amplitude requires at least two nadir observing satellites or a wide swath observing satellite. The significant impact of orbital parameters is also demonstrated: in particular, the Jason or GFO satellite orbits are found to be more suitable than the ENVISAT orbit. More generally, it is found that as soon as adequate sub-sampling exists (with periods of 5–10?days), the length of the repetitivity cycle of orbits does not have a significant impact.  相似文献   

Unstructured-mesh modeling of the Congo river-to-sea continuum     

Yoann Le Bars  Valentin Vallaeys  Éric Deleersnijder  Emmanuel Hanert  Loren Carrere  Claire Channelière 《Ocean Dynamics》2016,66(4):589-603

With the second largest outflow in the world and one of the widest hydrological basins, the Congo River is of a major importance both locally and globally. However, relatively few studies have been conducted on its hydrology, as compared to other great rivers such as the Amazon, Nile, Yangtze, or Mississippi. The goal of this study is therefore to help fill this gap and provide the first high-resolution simulation of the Congo river-estuary-coastal sea continuum. To this end, we are using a discontinuous-Galerkin finite element marine model that solves the two-dimensional depth-averaged shallow water equations on an unstructured mesh. To ensure a smooth transition from river to coastal sea, we have considered a model that encompasses both hydrological and coastal ocean processes. An important difficulty in setting up this model was to find data to parameterize and validate it, as it is a rather remote and understudied area. Therefore, an important effort in this study has been to establish a methodology to take advantage of all the data sources available including nautical charts that had to be digitalized. The model surface elevation has then been validated with respect to an altimetric database. Model results suggest the existence of gyres in the vicinity of the river mouth that have never been documented before. The effect of those gyres on the Congo River dynamics has been further investigated by simulating the transport of Lagrangian particles and computing the water age.  相似文献   

A morphometric analysis of gullies scoured by post-fire progressively bulked debris flows in southwest Montana, USA   总被引：2，自引：0，他引：2  

Emmanuel J. Gabet  Andy Bookter 《Geomorphology》2008,96(3-4):298

In the fall of 2001, an intense thunderstorm in southwest Montana triggered many debris flows in the burned area of Sleeping Child Creek. In most instances, the debris flows cut deep gullies into previously unchannelized colluvial hollows and deposited large volumes of sediment onto the valley floor. The presence of rill networks above the gullies as well as the absence of landslide features indicate that the gullies were scoured by progressively bulked debris flows, a process in which dilute surface runoff becomes increasingly more laden with sediment until it transforms into a debris flow. In this contribution, we present a morphometric analysis of six of the gullies to better understand this relatively understudied process. We find that the locations of the rill heads and gully heads conform to slope-area thresholds that are characteristic of erosion by overland flow. Our data also suggest that the volumes of the debris flows increase exponentially with normalized drainage area, thus lending support to an assumption used in a recently proposed debris flow incision law. Finally, the debris flow fans have been relatively unaltered since deposition, suggesting that the valley may be currently aggrading while the hillslopes are being denuded.  相似文献   

First Imaging of Coronal Mass Ejections in the Heliosphere Viewed from Outside the Sun – Earth Line     

Richard A. Harrison  Christopher J. Davis  Christopher J. Eyles  Danielle Bewsher  Steve R. Crothers  Jackie A. Davies  Russell A. Howard  Daniel J. Moses  Dennis G. Socker  Jeffrey S. Newmark  Jean-Philippe Halain  Jean-Marc Defise  Emmanuel Mazy  Pierre Rochus  David F. Webb  George M. Simnett 《Solar physics》2008,247(1):171-193

We show for the first time images of solar coronal mass ejections (CMEs) viewed using the Heliospheric Imager (HI) instrument aboard the NASA STEREO spacecraft. The HI instruments are wide-angle imaging systems designed to detect CMEs in the heliosphere, in particular, for the first time, observing the propagation of such events along the Sun – Earth line, that is, those directed towards Earth. At the time of writing the STEREO spacecraft are still close to the Earth and the full advantage of the HI dual-imaging has yet to be realised. However, even these early results show that despite severe technical challenges in their design and implementation, the HI instruments can successfully detect CMEs in the heliosphere, and this is an extremely important milestone for CME research. For the principal event being analysed here we demonstrate an ability to track a CME from the corona to over 40 degrees. The time – altitude history shows a constant speed of ascent over at least the first 50 solar radii and some evidence for deceleration at distances of over 20 degrees. Comparisons of associated coronagraph data and the HI images show that the basic structure of the CME remains clearly intact as it propagates from the corona into the heliosphere. Extracting the CME signal requires a consideration of the F-coronal intensity distribution, which can be identified from the HI data. Thus we present the preliminary results on this measured F-coronal intensity and compare these to the modelled F-corona of Koutchmy and Lamy (IAU Colloq. 85, 63, 1985). This analysis demonstrates that CME material some two orders of magnitude weaker than the F-corona can be detected; a specific example at 40 solar radii revealed CME intensities as low as 1.7×10⁻¹⁴ of the solar brightness. These observations herald a new era in CME research as we extend our capability for tracking, in particular, Earth-directed CMEs into the heliosphere.  相似文献