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141.
Gonzalo Sapriza Azuri Jorge Jódar Jesús Carrera Hoshin V. Gupta 《Mathematical Geosciences》2013,45(5):621-645
A model for generating daily spatial correlated rainfall fields suitable for evaluating the impacts of climate change on water resources is presented. The model, termed Stochastic Rainfall Generating Process, is designed to incorporate two major nonstationarities: changes in the frequencies of different precipitation generating mechanisms (frontal and convective), and spatial nonstationarities caused by interactions of mesoscale atmospheric patterns with topography (orographic effects). These nonstationarities are approximated as discrete sets of the time-stationary Stochastic Rainfall Generating Process, each of which represents the different spatial patterns of rainfall (including its variation with topography) associated with different atmospheric circulation patterns and times of the year (seasons). Each discrete Stochastic Rainfall Generating Process generates daily correlated rainfall fields as the product of two random fields. First, the amount of rainfall is generated by a transformed Gaussian process applying sequential Gaussian simulation. Second, the delimitation of rain and no-rain areas (intermittence process) is defined by a binary random function simulated by sequential indicator simulations. To explore its applicability, the model is tested in the Upper Guadiana Basin in Spain. The result suggests that the model provides accurate reproduction of the major spatiotemporal features of rainfall needed for hydrological modeling and water resource evaluations. The results were significantly improved by incorporating spatial drift related to orographic precipitation into the model. 相似文献
142.
Jesús Galindo-Zaldivar Francisco Gonzalez-Lodeiro Antonio Jabaloy 《Geodinamica Acta》2013,26(1):73-85
AbstractThe present contact caused by the superposition of the Alpujarride complex over that of the Nevado-Filabride in the western area of Sierra Nevada and Sierra de Filábres corresponds to a detachment. The deformation in the footwall associated with this contact, produced mylonitic fabrics with a significant stretching-lineation, over which brittle structures are superimposed. The deformation in the hanging wall associated with this contact is, on the other hand, essentially brittle. These deformations are subsequent to a series of syn-to post-metamorphic structures related to thrust phases.The micro- and meso-structures indicate that the hanging wall has moved towards the west-south-west.Other brittle structures, which began during the same extensional regime, are superimposed on the detachment and have continued to develop up to the present time. These structures were produced in an extensional regime with a non-coaxial deformation component and suggest the possibility of a tectonic evolution similar to that described for core complexes in the USA. 相似文献
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144.
Fernando Jesús Ballesteros Roselló 《Astrophysics and Space Science》2001,276(1):291-298
-ray telescopes based on coded-mask techniques does not give adirect image of the sky sources but its correlation with the mask responsefunction. To obtain an image of the sky sources one has to treatmathematically the detected image, usually by correlating it with areconstruction array (correlation methods). Unfortunately this kindof methods, although quite fast, have some limitations in the reconstructedimage and in handling the real telescope response.To improve these results, several reconstruction methods have been developedand used. In the case of LEGRI (a -ray coded-mask telescopedeveloped for the University of Valencia) we have used the EM algorithm,an iterative maximum likelihood algorithm with very good response andwith good handling of the telescope response. 相似文献
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146.
Vertical distribution and feeding types of nematodes from Chetumal Bay, Quintana Roo, Mexico 总被引:1,自引:0,他引:1
The vertical distribution and feeding type of nematodes in sediments of Chetumal Bay, Mexico, were studied in five intertidal transects along the urbanized zone in June and December 1995. Sediments were collected with a PVC corer to 6-cm sediment depth and cut immediately into three equal 2-cm depth fractions. Nematode density varied from 7.4 × 103 to 5.3 × 105 m?2 in June and from 1.7 × 104 to 7.2 × 105 m?2 in December. In June, the epistrate feederPseudochromadora sp. was the most abundant in the deepest sediment fraction (4–6 cm), whereas epistrate feeders,Neotonchoides sp.,Desmodora sp., and the deposit feederBathylaimus australis were dominant in the top most sediment (0–2 cm). In December, deposit feeders,Desmolaimus zeelandicus, Parodontophora sp., and the epistrate feederOncholaimus oxyuris were the most abundant in the deepest sediment, whereasNeotonchoides sp. andPseudochromadora sp. dominated the first 2 cm of sediments. Highest nematode density was recorded in the uppermost sediment layer (0–2 cm). Feeding types showed different abundance among transects and between months. There was a seasonal change in vertical distribution of nematodes, with the highest abundance in the deepest sediment layer in December, possibly due to the effect of wind waves on sediments of Chetumal Bay. The trophic composition of the nematode fauna in Chetumal Bay showed a dominance of deposit feeders and epistrate feeders, most likely in response to organic enrichment that is typical of eutrophic environments. 相似文献
147.
Jesús Solé Michael Cosca Zachary Sharp Pere Enrique 《International Journal of Earth Sciences》2002,91(5):865-881
The cooling history of Hercynian calc-alkalic, post-kinematic plutonic intrusions of the Montnegre massif (NE Spain) has been determined by 40Ar/39Ar analysis of two hornblendes, four biotites and eight K-feldspars (Kfs). The hornblendes have 40Ar/39Ar total fusion ages of 291Dž Ma and define the magmatic cooling of the basic and oldest structural intrusions. The biotites from the acid and intermediate rocks have 40Ar/39Ar plateau ages of 285Dž Ma, which date cooling of the intrusions through argon closure in biotite. The 40Ar/39Ar ages of the K-feldspars vary widely, ranging from 276-191 Ma. A correlation between K-feldspar 40Ar/39Ar total fusion age and several other features such as structural state, microstructures indicated by obliquity and, to some degree, optically visible perthites, is consistent with post-crystallisation partial argon loss in the K-feldspars. The 'D values of the biotites also correlate with age and chlorite contents, but this is not so for the '18O values of either feldspar or quartz. We infer that most microtextural changes occurred during cooling of the batholith, but a possibly Mesozoic, late disturbing hydrothermal event of weak intensity and with only minor fluid circulation must have occurred. This event provoked significant argon loss in the most structurally complex K-feldspars and is recorded in the hydrogen, but not oxygen, isotope data. 相似文献
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149.
Fernando A. López Mariano Matilla-García Jesús Mur Antonio Páez Manuel Ruiz 《Journal of Geographical Systems》2016,18(1):87-96
López et al. (Reg Sci Urban Econ 40(2–3):106–115, 2010) introduce a nonparametric test of spatial dependence, called SG(m). The test is claimed to be consistent and asymptotically Chi-square distributed. Elsinger (Reg Sci Urban Econ 43(5):838–840, 2013) raises doubts about the two properties. Using a particular counterexample, he shows that the asymptotic distribution of the SG(m) test may be far from the Chi-square family; the property of consistency is also questioned. In this note, the authors want to clarify the properties of the SG(m) test. We argue that the cause of the conflict is in the specification of the symbolization map. The discrepancies can be solved by adjusting some of the definitions made in the original paper. Moreover, we introduce a permutational bootstrapped version of the SG(m) test, which is powerful and robust to the underlying statistical assumptions. This bootstrapped version may be very useful in an applied context. 相似文献
150.
Quantifying the reefscape transformation of a coastal Caribbean coral reef during a phase shift and the associated coastal landscape change 下载免费PDF全文
Abigail Martínez‐ Rendis Gilberto Acosta González José Luis Hernández‐Stefanoni Jesús Ernesto Arias González 《Marine Ecology》2016,37(3):697-710
Caribbean coral reefs are under strong natural and human pressures and many have undergone phase shifts as a result of local and global change. However few studies have quantified the extent of these phase shifts and the potential impacts that they have on coral reef communities. A temporal comparative analysis of several coral reefscape and landscape metrics was conducted for data from Mahahual, Quintana Roo, Mexico, between the years 2000 and 2006, when a phase shift occurred. Landscape metrics were calculated from coral reef and coastal cover maps obtained by multispectral satellite image classification using IKONOS satellite imagery. These metrics showed that the coastal landscape and reefscape of Mahahual lost 85 ha of vegetation cover and 43 ha of coral cover over 6 years, respectively. Coastal landscape transformation was induced by the construction of a cruise ship pier and multiple associated tourist developments along the coast, such as hotels and restaurants, meanwhile alteration of the reefscape may be associated with potential stressors such as coastal development, bleaching events and hurricanes. 相似文献