A distribution function based bandwidth selection method for kernel quantile estimation     

Dany Faucher  Peter Funder Rasmussen  Bernard Bobe 《Journal of Hydrology》2001,250(1-4):1-11

The key problem in nonparametric frequency analysis of flood and droughts is the estimation of the bandwidth parameter which defines the degree of smoothing. Most of the proposed bandwidth estimators have been based on the density function rather than the cumulative distribution function or the quantile that are the primary interest in frequency analysis. We propose a new bandwidth estimator derived from properties of quantile estimators. The estimator builds on work by Altman and Léger (1995). The estimator is compared to the well-known method of least squares cross-validation (LSCV) using synthetic data generated from various parametric distributions used in hydrologic frequency analysis. Simulations suggest that our estimator performs at least as well as, and in many cases better than, the method of LSCV. In particular, the use of the proposed plug-in estimator reduces bias in the estimation as compared to LSCV. When applied to data sets containing observations with identical values, typically the result of rounding or truncation, the LSCV and most other techniques generally underestimates the bandwidth. The proposed technique performs very well in such situations.  相似文献   

Moisture analysis of an extratropical cyclone     

Dr. J. L. Rasmussen  Mr. R. W. Furman  Dr. H. Riehl 《Meteorology and Atmospheric Physics》1969,18(3-4):275-298

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Quantitative techniques in geography — An introduction | R. Hammond and P. McCullagh, 1978. Clarendon Press,Oxford, 2nd ed., 364 pp., £ 3.95 (paperback)     

W.O. Rasmussen 《Earth》1980,15(4):420-422

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Trace metal levels in coastal sea water investigation of Danish waters     

Bertil Magnusson  Leif Rasmussen 《Marine pollution bulletin》1982,13(3):84

The concentration levels of Cd (25 ng l^?1), Cu (0.45 μg l^?1), Ni (0.48 μg l^?1), Fe (0.2–7.0 μg l^?1), Pb (40 ng l^?1) and Zn (0.80 μg l^?1) have been determined in the Danish Sounds and in the Kattegat. Different sampling techniques have been used and analyses have been carried out separately by two different investigators, both using freon-extraction followed by determination by atomic absorption spectrometry (a.a.s.). Except for iron, found mainly in the particulate phase, the metals are found predominantly in a dissolved and labile (extractable) form. The results are compared with trace metal levels found in the two main water masses entering the Kattegat—the North Sea and the Baltic Sea.  相似文献   

Peculiarities in the stable isotope composition of organisms from an alpine lake     

Antonella?CattaneoEmail author  Marina?Manca  Joseph?B.?Rasmussen 《Aquatic Sciences - Research Across Boundaries》2004,66(4):440-445

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Groundwater recharge and evapotranspiration for two natural ecosystems covered with oak and heather     

U. L. Ladekarl  K. R. Rasmussen  S. Christensen  K. H. Jensen  B. Hansen 《Journal of Hydrology》2005,300(1-4):76-99

The evapotranspiration and groundwater recharge from two natural areas with high (oak) and low (heath) vegetation were estimated by calibrating a semi-physical numerical soil water and heat model to fit 8 and 7 years of TDR-measurements of water content, respectively. The measurements were made between the surface and 7 m depth. For the oak stand, the estimated annual recharge for the years 1992–1999 is 390 mm, the evaporation from soil and interception is 205 mm, and the transpiration is 285 mm. For the heath area estimation was carried out for the years 1993–1999. However, the heath was struck by a heavy beetle attack in 1994, which strongly affected the vegetation and thus the water balance for the following 3 years. For years not affected, the estimated recharge is 733 mm (about 50% larger than for the oak stand for the same years), the evaporation is 316 mm, and the transpiration is 128 mm. The estimated recharge values compare fairly well to estimates obtained from bromide tracer experiments. However, the recharge estimates obtained from the tracer experiments are very uncertain. The uncertainty is mainly due to spatial heterogeneity making the three replicate samples taken here for each time and depth insufficient.

The analyses of TDR-measurements and tracer data showed that water front movement depends on the antecedent soil water content. Some layers are bypassed, especially at low water contents, and at high soil water contents preferential flow was observed at the heath site.  相似文献   

Regional geological and tectonic structures of the North Sea area from potential field modelling   总被引：2，自引：1，他引：2  

S.B. Lyngsie  H. Thybo  T.M. Rasmussen   《Tectonophysics》2006,413(3-4):147-170

The spatial distribution of large-scale crustal domains and their boundaries are investigated in the North Sea area by combining gravity, magnetic and seismic data. The North Sea is situated on the plates of three continents, Avalonia, Laurentia and Baltica, which collided during the Caledonian orogeny in the middle Palaeozoic. The location and continuation of the collisional sutures are debated. We apply filters and transformations to potential field data to focus on the crystalline crust and uppermost mantle on a regional scale in order to extract new information on continental sutures. The transformations reveal intrinsic features of crustal transitions between the Caledonian plates and their relation to later extensional structures. The transformations include the Hough Transform applied to the gravity field, calculation of fractional derivatives and integrals of the gravity and magnetic fields, the pseudogravity field and the horizontal gradient field as well as upward continuation. The results indicate a fundamental difference between the lithosphere of Avalonia, Laurentia and Baltica. The location of the Mesozoic rift system (the Central Graben and Viking Graben), may have been partly determined by the presence of the sutures between these three plate, indicative of extensional reactivation of compressional structures. A significant lineament across the entire North Sea between Scotland and North Germany indicates that the lower crust of Baltica provenance may extend as far south-westward as to this lineament. Comparison of the power spectra of the gravity field in five selected areas shows significant differences in the long wavelength components between the areas north and south of the lineament corresponding to differences in crustal properties. This lineament could represent the suture between lithosphere of Caledonian origin (Avalonia) versus lithosphere of Precambrian origin (Baltica) in the lower crust and upper mantle. If this is the case, the lineament is the missing link in the reconstruction of the triple plate collision.  相似文献   

The Greenland Ice Core Chronology 2005, 15–42 ka. Part 1: constructing the time scale     

Katrine K. Andersen  Anders Svensson  Sigfus J. Johnsen  Sune O. Rasmussen  Matthias Bigler  Regine Rthlisberger  Urs Ruth  Marie-Louise Siggaard-Andersen  Jrgen Peder Steffensen  Dorthe Dahl-Jensen  Bo M. Vinther  Henrik B. Clausen 《Quaternary Science Reviews》2006,25(23-24):3246

The Greenland Ice Core Chronology 2005, GICC05, is extended back to 42 ka b2k (before 2000 AD), i.e. to the end of Greenland Stadial 11. The chronology is based on independent multi-parameter counting of annual layers using comprehensive high-resolution measurements available from the North Greenland Ice Core Project, NGRIP. These are measurements of visual stratigraphy, conductivity of the solid ice, electrolytical melt water conductivity and the concentration of Na⁺, Ca²⁺, SO₄²⁻, NO₃⁻, NH₄⁺. An uncertainty estimate of the time scale is obtained from identification of ‘uncertain’ annual layers, which are counted as 0.5±0.5 years. The sum of the uncertain annual layers, the so-called maximum counting error of the presented chronology ranges from 4% in the warm interstadial periods to 7% in the cold stadials. The annual accumulation rates of the stadials and interstadials are on average one-third and half of the present day values, respectively, and the onset of the Greenland Interstadials 2, 3, and 8, based on 20 year averaged δ¹⁸O values, are determined as 23,340, 27,780, and 38,220 yr b2k in GICC05.  相似文献   

An overview of trace metals in the environment, from mobilization to remediation   总被引：10，自引：0，他引：10  

A. C. L. Larocque  Patricia E. Rasmussen 《Environmental Geology》1998,33(2-3):85-91

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CHARACTERISTICS OF MESOSCALE FLOOD-MAKING TORRENTIAL RAIN SYSTEM SIMULATED BY HIGH RESOLUTION LIMITED AREA MODEL—NUMERICAL SIMULATION OF A HEAVY RAIN PROCESS DURING MEIYU SEASON IN 1991   总被引：1，自引：0，他引：1  

朱禾  E.Rasmussen 《Acta Meteorologica Sinica》1996,(3)

An experimental work on the transplant of high resolution limited area model(HIRLAM) isfirstly introduced into China.For the implementation,first of all is to adjust a new geographicalcoordination and to remove the instability caused by the Tibetan Plateau,the roof of the world.Then,we have applied this model to simulate a flood-making torrential rain process which occurredin the Changjiang-Huaihe River Valley in July 1991.That revealed the formation,development andmovement of a mesoseale heavy rain system which had made a disastrous flood event in the middleand lower reaches of Changjiang River Valley.The result encourages us to use the HIRLAM for the researches on the Meiyu belt,the salientfeature of precipitation of East Asia,and the numerical prediction of heavy rains in China.  相似文献