A non-parametric automatic blending methodology to estimate rainfall fields from rain gauge and radar data   总被引：1，自引：0，他引：1  

Carlos A. Velasco-Forero  Daniel Sempere-Torres  Eduardo F. Cassiraga  J. Jaime Gómez-Hernández 《Advances in water resources》2009

Quantitative estimation of rainfall fields has been a crucial objective from early studies of the hydrological applications of weather radar. Previous studies have suggested that flow estimations are improved when radar and rain gauge data are combined to estimate input rainfall fields. This paper reports new research carried out in this field. Classical approaches for the selection and fitting of a theoretical correlogram (or semivariogram) model (needed to apply geostatistical estimators) are avoided in this study. Instead, a non-parametric technique based on FFT is used to obtain two-dimensional positive-definite correlograms directly from radar observations, dealing with both the natural anisotropy and the temporal variation of the spatial structure of the rainfall in the estimated fields. Because these correlation maps can be automatically obtained at each time step of a given rainfall event, this technique might easily be used in operational (real-time) applications. This paper describes the development of the non-parametric estimator exploiting the advantages of FFT for the automatic computation of correlograms and provides examples of its application on a case study using six rainfall events. This methodology is applied to three different alternatives to incorporate the radar information (as a secondary variable), and a comparison of performances is provided. In particular, their ability to reproduce in estimated rainfall fields (i) the rain gauge observations (in a cross-validation analysis) and (ii) the spatial patterns of radar fields are analyzed. Results seem to indicate that the methodology of kriging with external drift [KED], in combination with the technique of automatically computing 2-D spatial correlograms, provides merged rainfall fields with good agreement with rain gauges and with the most accurate approach to the spatial tendencies observed in the radar rainfall fields, when compared with other alternatives analyzed.  相似文献   

Dual Kriging with Local Neighborhoods: Application to the Representation of Surfaces     

Juan Auñón  J. Jaime Gómez-Hernández 《Mathematical Geology》2000,32(1):69-85

Ordinary kriging, in its common formulation, is a discrete estimator in that it requires the solution of a kriging system for each point in space in which an estimate is sought. The dual formulation of ordinary kriging provides a continuous estimator since, for a given set of data, only a kriging system has to be estimated and the resulting estimate is a function continuously defined in space. The main problem with dual kriging up to now has been that its benefits can only be capitalized if a global neighborhood is used. A formulation is proposed to solve the problem of patching together dual kriging estimates obtained with data from different neighborhoods by means of a blending belt around each neighborhood. This formulation ensures continuity of the variable and, if needed, of its first derivative along neighbor borders. The final result is an analytical formulation of the interpolating surface that can be used to compute gradients, cross-sections, or volumes; or for the quick evaluation of the interpolating surface in numerous locations.  相似文献   

Modelling of chloride ingress into concrete through a single‐ion approach. Application to an idealized surface crack pattern     

Santiago Guzmán  Jaime C. Gálvez  José M. Sancho 《国际地质力学数值与分析法杂志》2014,38(16):1683-1706

The paper examines ion (chloride) transport equations in porous media (concrete) integrated over a representative elementary volume, that is to say, averaging over the macroscopic level the phenomena that occur really at the pore scale. There are three basic variables to be used: chloride concentration, moisture and temperature. The diffusion process is examined, in addition to other phenomena such as convection (the motion of dissolved substances caused by flow of water in a pore solution of partially saturated media) or chloride binding (the capacity of free chloride of being chemically bound, particularly with C₃A to form Friedel salts). Contrary to other approaches, such effects are not considered by means of apparent diffusion coefficients but by developing the complete set of time‐dependent equations for both the chloride concentration within the pore solution and the moisture content within the pore space. Once the general model is described, the system of equations can be solved numerically by means of a two‐dimensional finite element formulation. The main objective is to reproduce results of experimental tests by means of a priori parameter estimation, according to the characteristics of materials and external environment conditions, thereby superseding the well‐known best fit a posteriori through Fick's second equation. While the introduction of hygrometric conditions and convection phenomena appears to be of high significance, other factors like temperature, surface concentration, chloride binding or equivalent hydration time are analysed too. The proposed model can reproduce bidimensional complex geometries, for example, cracked concrete cover, as well as variable surface condition. An application case is developed through a realistic model of the geometry of a crack. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Zooplanktonic Communities of the Divergence Zone in the Northwestern Alboran Sea     

Jaime  Rodríguez  Alberto  García Valeriano  Rodriguez 《Marine Ecology》1982,3(2):133-142

Abstract. Using principal component analysis, the zooplanktonic communities of the divergence zone in the northwestern sector of the Alboran Sea were studied. The study was based on 35 vertical trawls in the 200 metres superficial level. The two first components account for 65 % of the total variance. The first component is a contrast between a warm water coastal community (characterized by low specific diversity and the abundance of Cladocera and Copepoda such as Acartia clausi, Centropages chierchiae and Temora stylifera) and a community of cold subsuperficial water distinguished by high specific diversity and a low number of individuals, one of its most characteristic elements being the eggs and larval stages of the Conostomasidae Maurolicus muelleri. The second component appears to be associated with an ecotone between the communities previously cited, and with a specific grouping (Rhincalanus nasutus, Eucalanus monachiis, Pseudocalanus elongatus, Temora longicornis , etc.) resulting from the peripheral displacement of subsuperficial elements brought to the surface by the cyclonic circulation of water masses between the Atlantic current and the Spanish coast.  相似文献   

A high sensitivity, low volume HPLC method to determine soluble reactive phosphate in freshwater and saltwater   总被引：1，自引：0，他引：1  

Jaime L. Haberer  Jay A. Brandes   《Marine Chemistry》2003,82(3-4):185-196

A reverse phase High Performance Liquid Chromatography (HPLC) method was developed to detect soluble reactive phosphate (SRP) in marine and freshwater samples. This technique is scalable over a range of sample volumes from 10 μl to 10 ml, requires minimal sample preparation, and responds linearly from 1 nM to 100 μM (R²>0.964). Standard Murphy–Riley molybdenum blue reagents were used to react with phosphate in samples for analysis. Solid phase extraction tubes were used to clean the mixed complexing reagent prior to combining the reagent with samples. The method was applied to freshwater samples collected in July 2001 along an Andean mountain stream located in the Eastern Cordillera (2400 m) of Peru and marine samples collected in January 2002 within the low marsh of the estuarine Nueces Delta System, Texas Coastal Bend. For method comparison, field samples were analyzed using a standard manual spectrophotometric method. Field sample phosphate concentrations produced from each method were nearly identical. This method offers the advantages of low sample volume (1 ml or less) with high sensitivity, precision, and potential automation.  相似文献   

Very massive stars: Evolution with mass loss     

Jaime Klapp 《Astrophysics and Space Science》1984,106(2):215-229

In a previous paper (Klapp, 1983) we have described the evolution of metal-free mass-losing very massive stars (VMS) in the 500–10 000M range. The present paper concerns to the nucleosynthesis and mass loss aspects of the hydrogen- and helium-burning phase. Through radiation driven winds, the star losses 20–40% of its mass as helium and 1% as carbon and oxygen. The results show that VMS cannot produce the cosmological helium abundance without overproducing heavier elements. The high oxygen yield of VMS makes them the best candidates for producing an oxygen overabundance in old Population II stars.  相似文献   

Cover Image          下载免费PDF全文

Maximiliano C.L. Rocca  Michael R. Rampino  Jaime L. Báez Presser 《地学学报》2017,29(4):i-i

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Reply to Comments on “Geophysical evidence for a large impact structure on the Falkland (Malvinas) Plateau”          下载免费PDF全文

Michael R. Rampino  Maximiliano C. L. Rocca  Jaime L. B. Presser 《地学学报》2017,29(6):416-419

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Erratum to: Distribution and thickness of sedimentary facies in the coastal dune, beach and nearshore sedimentary system at Maspalomas, Canary Islands     

Angela Fontán Bouzas  Javier Alcántara-Carrió  Isabel Montoya Montes  Andrés Barranco Ojeda  Silvia Albarracín  Jaime Rey Díaz de Rada  Jorge Rey Salgado 《Geo-Marine Letters》2013,33(2-3):231-231

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Suitability of GNSS for analysis of soil subsidence in Recife in a highly urbanized coastal area     

de Luna  Rejane Maria Rodrigues  dos Anjos Garnés  Silvio Jacks  da Silva Pereira Cabral  Jaime Joaquim  dos Santos  Sylvana Melo 《Natural Hazards》2021,106(3):1821-1837

Natural Hazards - Recife Metropolitan Region, in the northeast of Brazil, is formed by a coastal plain bounded by hills and by the Atlantic Ocean. Recife Metropolitan Region has about 4 million...  相似文献