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1.
Marie Drévillon Eric Greiner Denis Paradis Christophe Payan Jean-Michel Lellouche Guillaume Reffray Edmée Durand Stéphane Law-Chune Sylvain Cailleau 《Ocean Dynamics》2013,63(1):63-82
On the night of 1st June 2009, a Rio-Paris Air France flight (AF447) disappeared in a highly variable and poorly observed part of the western tropical Atlantic Ocean. The first debris was located 5 days after the accident. Several reverse drift computations were conducted in order to define the likely position of the wreckage. Unfortunately, the performance of the operational ocean analyses available in the region of interest ranges from 80 to 100 km of positioning error after 5 days of inverse drift computation. In preparation of the third phase of research of the wreckage at sea, a series of numerical experiments was performed at Météo-France and Mercator Océan in an attempt to better compute the surface currents in the region and for the period of the accident of the AF447 (May and June 2009). Tailored high-resolution atmosphere and ocean reanalyses were first produced respectively at Météo-France and Mercator Océan. Several nested experiments were then performed with a small and flexible ocean model limited to the region of interest. The date of the initial conditions and the type of atmospheric forcing fields were varied in order to produce a small ensemble from which information on the sensitivity to these changes could be derived. Probabilistic and statistical combinations between model and observations were tested and a solution was finally selected by means of a comparison of drift computations with independent surface drift observations. 相似文献
2.
Pichel WG Veenstra TS Churnside JH Arabini E Friedman KS Foley DG Brainard RE Kiefer D Ogle S Clemente-Colón P Li X 《Marine pollution bulletin》2012,65(1-3):28-41
Marine debris, particularly debris that is composed of lost or abandoned fishing gear, is recognized as a serious threat to marine life, vessels, and coral reefs. The goal of the GhostNet project is the detection of derelict nets at sea through the use of weather and ocean models, drifting buoys and satellite imagery to locate convergent areas where nets are likely to collect, followed by airborne surveys with trained observers and remote sensing instruments to spot individual derelict nets. These components of GhostNet were first tested together in the field during a 14-day marine debris survey of the Gulf of Alaska in July and August 2003. Model, buoy, and satellite data were used in flight planning. A manned aircraft survey with visible and IR cameras and a LIDAR instrument located debris in the targeted locations, including 102 individual pieces of debris of anthropogenic or terrestrial origin. 相似文献
3.
RÉSUMÉLes modèles pluie–débit sont fortement utilisés dans la gestion des risques hydrologiques et la prévision des crues. Dans cette étude, nous présentons un modèle pluie–débit pour la prévision des débits horaires basé sur la technique des réseaux de neurones artificiels (RNA). Ce modèle a été développé et appliqué sur le bassin versant de l’Eure au Nord-Ouest de la France afin de dépasser les problèmes dus à la non-linéarité de la relation pluie–débit et à l’imprécision des données collectées. La création de ce modèle a nécessité plusieurs étapes pendant lesquelles nous avons pu déterminer les paramètres du modèle permettant la compréhension de la complexité hydrologique et la production des informations nécessaires à la prévision. Elles ont abouti à un modèle de réseau de neurones artificiels capable d’effectuer, en quelques secondes, des prévisions des crues efficaces jusqu’à un horizon de prévision de 48 h. Ces résultats confirment que les modèles RNA peuvent jouer un rôle important dans le domaine de la prévision car capables de modéliser la non-linéarité des relations pluie–débit rencontrées sur certains bassins hydrologiques.
Editor Z.W. Kundzewicz Associate editor E. Gargouri 相似文献
4.
Résumé Dans le cadre des multifractals universels, il est possible de caractériser la variabilité spatio-temporelle de la pluie sur une grande gamme d’échelle à l'aide de trois paramètres invariants d’échelles. Dans cette étude, nous avons estimé ces paramètres multifractals sur des simulations numériques effectuées avec le modèle méso-échelle Méso-NH, développé par Météo-France et le Laboratoire d'Aérologie (Univ. P. Sabatier, Toulouse, France), et des images radar composites, couvrant le même événement pluvieux, à savoir un orage particulièrement violent, dit de type Cévenol, ayant eu lieu sur la partie sud de la France du 5 au 9 Septembre 2005. La comparaison des résultats montre que les deux types de données présentent des domaines d'invariance d’échelle relativement similaires, et dont les propriétés sont en accord avec les modèles de précipitation spatio-temporels unifiés et scalants les plus simples. Néanmoins l’évaluation de leurs exposants conduit à des valeurs parfois fortement différentes. Citation Gires, A., Tchiguirinskaia, I., Schertzer, D. & Lovejoy, S. (2011) Analyses multifractales et spatio-temporelles des précipitations du modèle Méso-NH et des données radar. Hydrol. Sci. J. 56(3), 380–396. 相似文献
5.
RésuméLa méthode SHYREG est une approche développée pour la connaissance régionale de l’aléa pluvial (SHYREG pluie) et hydrologique (SHYREG débit) en tout point du territoire français. Elle est basée sur le couplage d’un générateur stochastique de pluie horaire et d’un modèle hydrologique. Cet article présente les résultats de la mise en ?uvre de la méthode sur 1605 bassins versants répartis sur la France métropolitaine. Sur les fréquences courantes (c.à.d. périodes de retour inférieures à 10 ans), la méthode restitue correctement les quantiles de débit de crue ajustés à une loi statistique sur les observations (loi GEV, selon le critère de Nash-Sutcliffe). Plusieurs critères sont utilisés pour valider l’extrapolation des débits à des fréquences extrêmes: (a) en la confrontant à de longues chroniques de débits observés, (b) en analysant dans le modèle hydrologique la saturation du réservoir de production synonyme de comportement asymptotique avec les pluies, et (c) en étudiant la stabilité de la méthode à travers les critères statistiques.
Editeur Z.W. Kundzewicz; Editeur associé G. MahéCitation Aubert, Y., Arnaud, P., Ribstein, P., et Fine, J.-A., 2014. La méthode SHYREG débit, application sur 1605 bassins versants en France Métropolitaine. Hydrological Sciences Journal, 59 (5), 993–1005. 相似文献
6.
Jianzhong Ge Pingxing Ding Changsheng Chen Song Hu Gui Fu Lunyu Wu 《Ocean Dynamics》2013,63(8):881-900
A high-resolution numerical model system is essential to resolve multi-scale coastal ocean dynamics. So a multi-scale unstructured grid-based finite-volume coastal ocean model (FVCOM) system has been established for the East China Sea and Changjiang Estuary (ECS–CE) with the aim at resolving coastal ocean dynamics and understanding different physical processes. The modeling system consists of a three-domain-nested weather research and forecasting model, FVCOM model with the inclusion of FVCOM surface wave model in order to understand the wave–current interactions. The ECS–CE system contains three different scale models: a shelf-scale model for the East China Sea, an estuarine-scale model for the Changjiang Estuary and adjacent region, and a fine-scale model for the deep waterway regions. These three FVCOM-based models guarantee the conservation of mass and momentum transferring from outer domain to inner domain using the one-way common-grid nesting procedure. The model system has been validated using data from various observation data, including surface wind, tides, currents, salinity, and wave to accurately reveal the multi-scale dynamics of the East China Sea and Changjiang Estuary. This modeling system has been demonstrated via application to the seasonal variations of Changjiang diluted water and the bottom saltwater intrusion in the North Passage, and it shows strong potential for estuarine and coastal ocean dynamics and operational forecasting. 相似文献
7.
Résumé Les espaces urbanisés soumis à des risques modérés d'inondation pour les vies humaines sont souvent peu considérés dans les études sur la vulnérabilité aux risques naturels en dépit des enjeux qu'ils représentent en termes de gestion de crise. Comment les riverains y font-ils face au danger et quelles sont leurs « bonnes raisons » d'agir? A partir de l’étude socio-géographique de deux inondations récentes (2000 et 2003) dans la périphérie toulousaine (Sud-Ouest de la France), nous montrons que les caractéristiques de l'aléa dans les vallées étudiées influencent les représentations du risque et par conséquent les motivations à se protéger. Face au risque majeur, la vulnérabilité sociale se trouve ainsi augmentée. Pour améliorer la résilience des populations, il convient d'adapter la communication sur les risques: personnaliser l'information, améliorer la compréhension de l’événement vécu et mobiliser de nouvelles formes de médiation entre gestionnaires et riverains. Editeur Z.W. Kundzewicz Citation Becerra, S., Peltier, A., Antoine, J.M., Labat, D., Chorda, J., Ribolzi, O., Daupras, F., et Dartus, D., 2013. Comprendre les comportements face à un risque modéré d'inondation. Etude de cas dans le périurbain toulousain (Sud-Ouest de la France). Hydrological Sciences Journal, 58 (5), 945–965. 相似文献
8.
A sodar was deployed at Roissy–Charles de Gaulle airport near Paris, France, in 2008 with the aim of improving the forecast of low visibility conditions there. During the winter of 2008–2009, an experiment was conducted that showed that the sodar can effectively detect and locate the top of fog layers which is signaled by a strong peak of acoustic reflectivity. The peak is generated by turbulence activity in the inversion layer that contrasts sharply with the low reflectivity recorded in the fog layer below. A specific version of the 1D-forecast model deployed at Roissy for low visibility conditions (COBEL-ISBA) was developed in which fogs’ thicknesses are initialized by the sodar measurements rather than the information derived from the down-welling IR fluxes observed on the site. It was tested on data archived during the winters of 2008–2009 and 2009–2010 and compared to the version of the model presently operational. The results show a significant improvement—dissipation times of fogs are better predicted. 相似文献
9.
Jean-Christophe Pouget David Proaño Andrea Vera Marcos Villacís Thomas Condom Marisa Escobar 《水文科学杂志》2017,62(3):431-446
La forte croissance socio-économique de Quito a conduit à d’importants projets de transferts interbassins, intensifiant la mobilisation des ressources d’altitude situées dans des zones écologiques sensibles et connaissant une fonte accélérée des glaciers. Afin d’étudier divers scénarios d’évolutions, nous proposons une modélisation du continuum climat/glacier/hydrologie/gestion des ressources en eau. Utilisant l’outil Water Evaluation and Planning (WEAP), nous avons développé : (1) une modélisation hydro-climatologique semi-distribuée avec des données mensuelles homogénéisées par vectorisation régionale ; (2) une modélisation de la production en eau des glaciers et de leur évolution interannuelle ; (3) une modélisation en unités hydrologiques distinguant différentes couvertures de sols ; et (4) une modélisation de la gestion distinguant droits, allocation et usages de l’eau. Nous présentons les résultats du calage hydrologique mensuel (1963–2006), en étudiant particulièrement l’équifinalité de diverses paramétrisations. Nous montrons la souplesse, la robustesse et les limites de la modélisation proposée, contribuant à cerner différentes incertitudes dans l’évaluation de scénarios prospectifs. 相似文献
10.
In 1996 a large debris flow occurred on the fan of the Chalance torrent system, a tributary of the Séveraisse river, French Alps. To investigate the magnitude and frequency of such debris flows on this fan, fieldwork was carried out in the summer of 1998. Detailed investigation revealed that several debris flows have occurred in the past 200 years. Lichenometry was used as a dating technique to obtain the frequency of these debris‐flow events. Also the volume of these flows was estimated. With these data a magnitude–frequency relationship was constructed. This relationship shows a maximum magnitude of at least 50 × 103 m3. Based on data for the past c. 150 years, a debris flow of such a volume appears to have a recurrence interval of approximately 34 years. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
11.
Pierre Mechler Raouf Mseddi Emile Okal Jean-Louis Plantet Yves Rocard 《Physics of the Earth and Planetary Interiors》1974,8(3):269-276
In this paper, we give a model of the 600-km discontinuity under France, which explains large travel-time and amplitude anomalies on teleseisms as recorded in the French network. It features a large descent from the Ardennes to the Pyrénées, of which tectonic implications are discussed. 相似文献
12.
At-sea detection of marine debris: overview of technologies, processes, issues, and options 总被引：1，自引：0，他引：1
Mace TH 《Marine pollution bulletin》2012,65(1-3):23-27
At-sea detection of marine debris presents a difficult problem, as the debris items are often relatively small and partially submerged. However, they may accumulate in water parcel boundaries or eddy lines. The application of models, satellite radar and multispectral data, and airborne remote sensing (particularly radar) to focus the search on eddies and convergence zones in the open ocean appear to be a productive avenue of investigation. A multistage modeling and remote sensing approach is proposed for the identification of areas of the open ocean where debris items are more likely to congregate. A path forward may best be achieved through the refinement of the Ghost Net procedures with the addition of a final search stage using airborne radar from an UAS simulator aircraft to detect zones of potential accumulation for direct search. Sampling strategies, direct versus indirect measurements, remote sensing resolution, sensor/platform considerations, and future state are addressed. 相似文献
13.
Fabien Thollet Christophe Rousseau Benoit Camenen Stephane Boubkraoui Flora Branger François Lauters Julien Némery 《水文研究》2021,35(2):e14044
We present a dataset on to the Arc-Isère long-term environmental research observatory, which is part of the Rhône Basin Long Term Environmental Research Observatory. This alpine catchment located in the French Alps is characterized by high Suspended Particulate Matter (SPM) in anthropogenized valleys. Suspended Sediment Concentrations (SSC) naturally observed in the river are very high, ranging from a few tens of milligrams per litre at low flow to tens of grams per litre during major natural hydrological events (floods, debris flows) or river dam hydraulic flushes. One research objective related to this site is to better understanding the SSC dynamics along the river using a system of nested catchments (Arvan, Arc, and Isère) in order to assess both temporal and spatial dynamics. The data allow the quantification of fine sediment yields and also the evaluation of possible morphological changes due to fine sediment deposition or resuspension. Additionally, the observatory database support studies on contaminants (either dissolved or particulate contaminants). Our monitoring includes six stations with high frequency (2–30 min) streamflow, SSC measurement using turbidity sensors, and associated automatic sampling. Discharge is measured via water level measurements and a rating curve. The oldest station (Grenoble-campus) started recording discharge and concentration data from April 2006 while others stations were built between 2009 and 2011. Data are available in an online data website called ‘Base de Données des Observatoires en Hydrologie’ (Hydrological observatory database, https://bdoh.irstea.fr/ARC-ISERE/ ) with a DOI reference for the dataset. The hydrological and sediment transport time series are stored, managed and made available to a wide community with unfettered access in order to be used at their full extent. This database is used as a data exchange tool for both scientists and operational end-users and there is an associated online tool to compute integrated fluxes. 相似文献
14.
A global ocean circulation model is coupled to a particle-tracking model to simulate the transport of floating debris washed into the North Pacific Ocean by the Tohoku tsunami. A release scenario for the tsunami debris is based on coastal population and measured tsunami runup. Archived 2011/2012 hindcast current data is used to model the transport of debris since the tsunami, while data from 2008 to 2012 is used to investigate the distribution of debris on timescales up to 4 years. The vast amount of debris pushed into ocean likely represents thousands of years worth of ‘normal’ litter flux from Japan’s urbanized coastline. This is important since a significant fraction of the debris will be comprised of plastics, some of which will degrade into tiny particles and be consumed by marine organisms, thereby allowing adsorbed organic pollutants to enter our food supply in quantities much higher than present. 相似文献
15.
A water-fluid mud coupling model is developed based on the unstructured grid finite volume coastal ocean model (FVCOM) to investigate the fluid mud motion. The hydrodynamics and sediment transport of the overlying water column are solved using the original three-dimensional ocean model. A horizontal two-dimensional fluid mud model is integrated into the FVCOM model to simulate the underlying fluid mud flow. The fluid mud interacts with the water column through the sediment flux, current, and shear stress. The friction factor between the fluid mud and the bed, which is traditionally determined empirically, is derived with the assumption that the vertical distribution of shear stress below the yield surface of fluid mud is identical to that of uniform laminar flow of Newtonian fluid in the open channel. The model is validated by experimental data and reasonable agreement is found. Compared with numerical cases with fixed friction factors, the results simulated with the derived friction factor exhibit the best agreement with the experiment, which demonstrates the necessity of the derivation of the friction factor. 相似文献
16.
Deciphering orogenic evolution requires the integration of a growing number of geological and geophysical techniques on various spatial and temporal scales. Contrasting visions of mountain building and lithospheric deformation have been proposed in recent years. These models depend on the respective roles assigned to the mantle, the crust or the sediments. This article summarizes the contents of the Special Issue dedicated to ‘Geodynamics and Orogenesis’ following the ‘Réunion des Sciences de la Terre’ 2010 conference held in Bordeaux, France. Further, based on the example of the Western Alps-Mediterranean domain we emphasize the possibility to integrate long and short term, plate- to sample-scale, datasets in order to constrain orogenic evolution. 相似文献
17.
Michel Cara Marylin Denieul Olivier Sèbe Bertrand Delouis Yves Cansi Antoine Schlupp 《Journal of Seismology》2017,21(3):551-565
The recent seismicity catalogue of metropolitan France Sismicité Instrumentale de l’Hexagone (SI-Hex) covers the period 1962–2009. It is the outcome of a multipartner project conducted between 2010 and 2013. In this catalogue, moment magnitudes (M w) are mainly determined from short-period velocimetric records, the same records as those used by the Laboratoire de Détection Géophysique (LDG) for issuing local magnitudes (M L) since 1962. Two distinct procedures are used, whether M L-LDG is larger or smaller than 4. For M L-LDG >4, M w is computed by fitting the coda-wave amplitude on the raw records. Station corrections and regional properties of coda-wave attenuation are taken into account in the computations. For M L-LDG ≤4, M w is converted from M L-LDG through linear regression rules. In the smallest magnitude range M L-LDG <3.1, special attention is paid to the non-unity slope of the relation between the local magnitudes and M w. All M w determined during the SI-Hex project is calibrated according to reference M w of recent events. As for some small events, no M L-LDG has been determined; local magnitudes issued by other French networks or LDG duration magnitude (M D) are first converted into M L-LDG before applying the conversion rules. This paper shows how the different sources of information and the different magnitude ranges are combined in order to determine an unbiased set of M w for the whole 38,027 events of the catalogue. 相似文献
18.
Résumé L'analyse des renseignements fournis par 18 stations situées en France métropolitaine, permet de distinguer trois principaux types d'apports d'aérosols radioactifs: 1) Un apport résultant d'une répartition régulière et homogène au sein des nuages; 2) Un régime de retombées, réparties uniformément, mais indépendant du système nuageux; 3) Un régime d'apport irrégulier et indépendant des condensations. Ces trois régimes se suivent et se succèdent d'une manière continue. Le régime 3 caractérise les explosions récentes, le régime 1 devient prédominant au bout d'une dizaine de mois.
Summary The data analysis of eighteen stations located in France have shown the possibility of distinguishing several main types of transport. The first type of transport shows a perfectly regular and homogeneous distribution of radioactive debris in clouds. The second type of transport results in a regular distribution of debris over the country independent of the clouds systems. In the third type the debris is distributed irregularly and the fall-out is perfectly independent of the cloud-rain system. The three types follow each other in a way continuous with time. The irregular and independent transport type immediately follows the explosions. The regular distribution of debris, but still independent of the cloud system, comes later and the debris will be mainly of tropospheric origin. The irregular and non homogeneous distributions of debris will be characteristic of recent explosions and correspond to fall-out of tropospheric origin.相似文献
19.
Pierre Javelle Julie Demargne Dimitri Defrance Jean Pansu Patrick Arnaud 《水文科学杂志》2014,59(7):1390-1402
AbstractThis article presents a comparison between real-time discharges calculated by a flash-flood warning system and post-event flood peak estimates. The studied event occurred on 15 and 16 June 2010 at the Argens catchment located in the south of France. Real-time flood warnings were provided by the AIGA (Adaptation d’Information Géographique pour l’Alerte en Crue) warning system, which is based on a simple distributed hydrological model run at a 1-km2 resolution using radar rainfall information. The timing of the warnings (updated every 15 min) was compared to the observed flood impacts. Furthermore, “consolidated” flood peaks estimated by an intensive post-event survey were used to evaluate the AIGA-estimated peak discharges. The results indicated that the AIGA warnings clearly identified the most affected areas. However, the effective lead-time of the event detection was short, especially for fast-response catchments, because the current method does not take into account any rainfall forecast. The flood peak analysis showed a relatively good correspondence between AIGA- and field-estimated peak values, although some differences were due to the rainfall underestimation by the radar and rainfall–runoff model limitations.
Editor Z.W. Kundzewicz; Guest editor R.J. MooreCitation Javelle, P., Demargne, J., Defrance, D., Pansu, J. and Arnaud, P., 2014. Evaluating flash-flood warnings at ungauged locations using post-event surveys: a case study with the AIGA warning system. Hydrological Sciences Journal, 59 (7), 1390–1402. http://dx.doi.org/10.1080/02626667.2014.923970 相似文献
20.
H. P. Schmitz 《Ocean Dynamics》1965,18(3):97-113
Zusammenfassung Es wird ein auf Probleme der dynamischen Meteoro-Hydrographie erfolgreich angewandtes Differenzengleichungssystem er?rtert,
dessen numerische Stabilit?t, unabh?ngig von der geographischen Breite, auch bei gro?er Tiefe und sehr kleinem Horizontaldiffusionskoeffizienten
gew?hrleistet ist. Für Anwendungen auf meridional stark ausgedehnte Ozeane, z. B. bei Gezeitenrechnungen, werden die durch
Verwendung von Kugelkoordinaten erforderlichen Erweiterungen abgeleitet.
A system of finite difference equations for computations of instationary motions in an ocean with small eddy viscosity
Summary A system of finite difference equations successfully applied to some problems of dynamical meteoro-hydrography is discussed. Its numerical stability may also be fitted in cases of very small horizontal eddy diffusity and large depths independend of the latitude. For the purpose of applications to meridionally far extended oceans, for instance when dealing with tidal computations, the necessary completations due to the employment of spherical polar coordinates are derived.
Un système d'équations aux différences finies permettant le calcul de mouvements non stationnaires dans une mer à faible frottement de turbulence
Résumé On discute d'un système d'équations aux différences finies appliqué avec succès à des problèmes de météoro-hydrographie dynamique. Du fait de sa stabilité numérique, indépendante de la latitude, ce système reste également valable dans le cas des grandes profondeurs et pour de très faibles coefficients de diffusion horizontale. Pour ses applications dans les océans à grande extension méridienne, par exemple aux calculs de marées, on en tire les développements que nécessite l'emploi de coordonnées sphériques.相似文献