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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
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Abstract. Red tides of the toxic dinoflagellate Pyrodinium bahamense var. compressum have occurred almost annually since 1976 in the coastal waters of the west coast of Sabah, Malaysia. Field obSérvations have indicated that the timings of these outbreaks could be linked to meteorological forcings. All the red tides have occurred during either the northeast or southwest monsoon periods. Matching of red tide outbreaks with total monthly rainfall, monthly-averaged index of wind-induced surface water mixing, and monthly-averaged upwelling index for the period from 1975 to 1989 failed to show any definite pattern. However, more red tide events occurred in months with high mixing index values. The absence of definable patterns could be due to the use of monthly, rather than daily, values in the calculations. 相似文献
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ABSTRACTIn this paper a universal multifractals comparison of the outputs of two types of collocated optical disdrometers installed on the roof of the Ecole des Ponts ParisTech is performed. A Campbell Scientific PWS100 which analyses the light scattered by the hydrometeors and an OTT Parsivel2 which analyses the portion of occluded light are deployed. Both devices provide a binned distribution of drops according to their size and velocity. Various fields are studied across a range of scales: rain rate (R), liquid water content (ρ), polarimetric weather radar quantities such the horizontal reflectivity (Zh) and the specific differential phase (Kdp), and drop size distribution (DSD) parameters such as the total drop concentration (Nt) and the mass-weighted diameter (Dm). For both devices, good scaling is retrieved on the whole range of available scales (2?h–30?s), except for the DSD parameters for which the scaling only holds down to few minutes. For R, the universal multifractal parameters are found to equal 1.5 and 0.2 for α and C1, respectively. Results are interpreted with the help of the classical Zh–R and R–Kdp radar relations.
Editor D. Koutsoyiannis; Associate editor E. Volpi 相似文献
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Peter M. Allen Jeffrey G. Arnold Lance Auguste Joseph White John Dunbar 《地球表面变化过程与地形》2018,43(1):202-217
Gully erosion begins in streambanks and uplands as a consequence of adjustments in driving forces on the landscape imposed by changes in land use or climate. The deleterious effects of gullies worldwide have led to many site‐specific studies of gully form and function. In the continental United States, gully erosion in agricultural land has destroyed valuable farmland yet, prediction of gully processes remains problematic on a national scale. This research has proposed a simple method to predict gully headcut advance. When combined with SWAT hydrologic flow routines, the model predicted gully headcut advance with reasonable accuracy on a daily time step for time periods exceeding two decades. The model was tested in two distinct land resource areas of the United States with differing climate, soils, cover and drainage. The inputs for the headcut model have been kept simple as the model will be applied over large areas. Model inputs consist of headcut height, headcut resistance (based on soil erodibility and a root‐cover factor), and daily flow. The model is compared with an annual time step model used in assessment of headcut advance and appears to offer a better way to assess gully headcut advance. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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Bianca Alves de Souza Igor da Silva Rocha Paz Abdellah Ichiba Bernard Willinger Auguste Gires Jose Carlos Cesar Amorim 《水文科学杂志》2013,58(11):1619-1635
ABSTRACTThe spread of impervious surfaces in urban areas combined with the rise in the intensity of rainfall events as a result of climate change has led to dangerous increases in storm water flows. This paper discusses a new implementation of the fully distributed hydrological model Multi-Hydro (developed at École des Ponts ParisTech), when operating storage basins, and its ability to deal with high-resolution radar rainfall data. The peri-urban area of Massy (south of Paris, France) was selected as a case study for having six of these drainage facilities, used extensively in flood control. Two radar rainfall datasets with different spatiotemporal resolutions were used: Météo-France’s PANTHER rainfall product (C-band) and ENPC’s X-band DPSRI. The rainfall spatiotemporal variability was analysed statistically using Universal Multifractals (UM). Finally, to validate the application, the water level simulations were compared with local measurements in the Cora storage basin located next to the catchment’s single outlet. 相似文献
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J.-J. Bahain C. Falguères J.-M. Dolo P. Antoine P. Auguste N. Limondin-Lozouet J.-L. Locht A. Tuffreau H. Tissoux S. Farkh 《Quaternary Geochronology》2010,5(2-3):371-375
During the last two decades, extensive road-construction works in Northern France have allowed the discovery of numerous Middle Palaeolithic sites. Geological and multidisciplinary studies performed on these localities allowed the establishment of a precise chronostratigraphical and biostratigraphical framework of regional significance, which could be correlated to the global marine palaeoclimatic scale. Each human occupation layer has been linked to this regional framework, thus providing a stratigraphical age-control for the Middle Palaeolithic human settlements of this area.At the same time, a program of geochronological studies was developed using TL, OSL, U-series, ESR and, as often as possible, ESR/U-series methods. Hence, bones and teeth recovered from archaeological sites of Savy, Ault, Caours, Gentelles and La Celle-sur-Seine, were analyzed and the results compared to the chronostratigraphical ages. The age results are generally in good agreement with the geological data while bones and dental tissues display in some cases U-series ages higher that the EU-ESR ones, suggesting U-loss phenomena. 相似文献
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ABSTRACTScale issues are ubiquitous in geosciences. Because of their simplicity and intuitiveness, and despite strong limitations, notably its non-stationarity features, discrete random multiplicative cascade processes are very often used to address these scale issues. A novel approach based on the parsimonious framework of Universal Multifractals (UM) is introduced to tackle this issue while preserving the simple structure of discrete cascades. It basically consists in smoothing at each cascade step the random multiplicative increments with the help of a geometric interpolation over a moving window. The window size enables to introduce non-conservativeness in the simulated fields. It is established theoretically,] and numerically confirmed, that the simulated fields also exhibit a multifractal behaviour with expected features. It is shown that such an approach remains valid over a limited range of UM parameters. Finally, we test downscaling of rainfall fields with the help of this blunt discrete cascade process, and we discuss challenges for future developments. 相似文献
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Affoué Berthe Yao Bi Tié Albert Goula Alioune Kane Oi Mangoua Jules Mangoua Kouamé Auguste Kouassi 《水文科学杂志》2013,58(5):856-867
RÉSUMÉCe travail aborde le problème d’accessibilité en eau potable dans les zones fissurées de la Côte d’Ivoire notamment en saison sèche. Sur le bassin versant de la Lobo, le problème se pose avec plus d’acuité puisque les retenues aménagées pour l’alimentation en eau des populations ne sont pas correctement alimentées ces dernières années et sujettes à une très forte eutrophisation. L’approche pluridisciplinaire (télédétection, analyse multicritère et système d’information hydrogéologique à référence spatiale) a été adoptée. La cartographie des sites potentiels en eau montre que la quasi-totalité du bassin de la Lobo possède une bonne et excellente disponibilité en eau souterraine (93% de la superficie totale). Cette bonne disponibilité en eau souterraine est due à une faible pente et à une bonne densité de fracturation qui entrainent une bonne infiltration des eaux dans l’aquifère. L’identification des sites potentiels montre que près de 72% de la superficie du bassin est favorable à l’implantation d’ouvrages à gros débits. Dans l’ensemble, ces aquifères présentent une bonne accessibilité avec cependant, une exploitabilité médiocre.
Editeur Z. W. Kundzewicz; Edithur Associé M.D. Fidelibus 相似文献
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